Monomers for thermosetting and toughening epoxy resins. [glycidyl amine derivatives, propargyl-containing amines, and mutagenic testing of aromatic diamines

NASA Technical Reports Server (NTRS)

Pratt, J. R.

1981-01-01

Eight glycidyl amines were prepared by alkylating the parent amine with epichlorohydrin to form chlorohydrin, followed by cyclization with aqueous NaOH. Three of these compounds contained propargyl groups with postcuring studies. A procedure for quantitatively estimating the epoxy content of these glycidyl amines was employed for purity determination. Two diamond carbonates and several model propargly compounds were prepared. The synthesis of three new diamines, two which contain propargyloxy groups, and another with a sec-butyl group is in progress. These materials are at the dinitro stage ready for the final hydrogenation step. Four aromatic diamines were synthesized for mutagenic testing purposes. One of these compounds rapidly decomposes on exposure to air.

40 CFR 180.341 - 2,4-Dinitro-6-octylphenyl crotonate and 2,6-dinitro-4-octylphenyl crotonate; tolerances for...

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 23 2010-07-01 2010-07-01 false 2,4-Dinitro-6-octylphenyl crotonate and 2,6-dinitro-4-octylphenyl crotonate; tolerances for residues. 180.341 Section 180.341 Protection... EXEMPTIONS FOR PESTICIDE CHEMICAL RESIDUES IN FOOD Specific Tolerances § 180.341 2,4-Dinitro-6-octylphenyl...

40 CFR 180.341 - 2,4-Dinitro-6-octylphenyl crotonate and 2,6-dinitro-4-octylphenyl crotonate; tolerances for...

Code of Federal Regulations, 2011 CFR

2011-07-01

... EXEMPTIONS FOR PESTICIDE CHEMICAL RESIDUES IN FOOD Specific Tolerances § 180.341 2,4-Dinitro-6-octylphenyl... established for combined negligible residues of a fungicide and insecticide that is a mixture of 2,4-dinitro-6...

Poly[(μ-3,5-dinitro­benzoato)(μ-3,5-dinitro­benzoic acid)rubidium

PubMed Central

Miao, Yanqing; Fan, Tao

2011-01-01

The asymmetric unit of the title compound, [Rb(C7H3N2O6)(C7H4N2O6)]n, comprises an Rb+ cation, a 3,5-dinitro­benzoate anion and a 3,5-dinitro­benzoic acid ligand. The Rb+ cation is nine-coordinated by O atoms from four 3,5-dinitro­benzoate anions and three neutral 3,5-dinitro­benzoic acid ligands. The metal atom is firstly linked by four bridging carboxyl groups, forming a binuclear motif, which is further linked by the nitro groups into a two-dimensional framework along the [110] direction. A short O—H⋯O hydrogen bond between two adjacent carboxy/carboxylate groups occurs. PMID:22090832

Methods for performing electrochemical nitration reactions

DOEpatents

Lister, Tedd Edward; Fox, Robert Vincent

2010-05-11

A method for the electrochemical synthesis of dinitro compounds is disclosed. The method comprises using an anode to oxidize an inactive chemical mediator, such as a ferrocyanide (Fe(CN).sub.6.sup.-4) ion, to an active chemical mediator or oxidizing agent, such as a ferricyanide (Fe(CN).sub.6.sup.-3) ion, in the presence of a differential voltage. The oxidizing agent reacts with a nitro compound and a nitrite ion to form a geminal dinitro compound. The anode may continuously oxidize ferrocyanide to regenerate active ferricyanide, thus keeping sufficient amounts of ferricyanide available for reaction..

Synthesis, characterization and biological assay of Salicylaldehyde Schiff base Cu(II) complexes and their precursors

NASA Astrophysics Data System (ADS)

Iftikhar, Bushra; Javed, Kanwal; Khan, Muhammad Saif Ullah; Akhter, Zareen; Mirza, Bushra; Mckee, Vickie

2018-03-01

Three new Schiff base ligands were synthesized by the reaction of Salicylaldehyde with semi-aromatic diamines, prepared by the reduction of corresponding dinitro-compounds, and were further used for the formation of complexes with Cu(II) metal ion. The structural features of the synthesized compounds were confirmed by their physical properties and infrared, electronic and NMR spectroscopic techniques. The studies revealed that the synthesized Schiff bases existed as tetradentate ligands and bonded to the metal ion through the phenolic oxygen and azomethine nitrogen. One of the dinitro precursors was also analyzed by single crystal X-ray crystallography, which showed that it crystallizes in monoclinic system with space group P2/n. The thermal behavior of the Cu(II) complexes was determined by thermogravimetric analysis (TGA) and kinetic parameters were evaluated from the data. Schiff base ligands, their precursors and metal complexes were also screened for antibacterial, antifungal, antitumor, Brine shrimp lethality, DPPH free radical scavenging and DNA damage assays. The results of these analyses indicated the substantial potential of the synthesized Schiff bases, their precursors and Cu(II) complexes in biological field as future drugs.

Human Cell Line Activation Test of the Novel Energetics 2,6-pyrazinediamine 3,5-dinitro 1 -oxide (LLM-105) and 2,4,6-trinitro-3-bromoanisole (TNBA)

DTIC Science & Technology

2017-11-06

substances early in the RDT&E process to avoid unnecessary costs, conserve physical resources, and sustain the health of those potentially exposed. The SERDP...pyrazinediamine 3,5-dinitro 1 –oxide (LLM-105) and 2,4,6-trinitro-3-bromoanisole (TNBA) Prepared by: Emily Reinke, Ph.D. Health Effects Division...Toxicology Directorate Army Public Health Center ARIMS designation: 500c Use of trademarked name(s) does not imply endorsement by the U.S

40 CFR 721.1000 - Benzenamine, 3-chloro-2,6-dinitro-N,N-dipropyl-4-(tri-fluoro-methyl)-.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Benzenamine, 3-chloro-2,6-dinitro-N,N-dipropyl-4-(tri-fluoro-methyl)-. 721.1000 Section 721.1000 Protection of Environment ENVIRONMENTAL... Significant New Uses for Specific Chemical Substances § 721.1000 Benzenamine, 3-chloro-2,6-dinitro-N,N...

Preparation of 1,1'-dinitro-3,3'-azo-1,2,4-triazole. [1,1'-dinitro-3,3'-azo-1,2,4-triazole

DOEpatents

Lee, K.Y.

1985-03-05

A new high density composition of matter, 1,1'-dinitro-3,3'-azo-1,2,4-triazole, has been synthesized using inexpensive, commonly available compounds. This compound has been found to be an explosive, and its use as a propellant is anticipated. 1 fig., 1 tab.

Poly[(μ5-3,5-dinitro­benzoato)rubidium

PubMed Central

Miao, Yanqing; Zhang, Xiaoqing; Liu, Chunye

2011-01-01

The asymmetric unit of the title compound, [Rb(C7H3N2O6)]n, comprises an Rb cation and a 3,5-dinitro­benzoate anion. The Rb cation is eight-coordinated by O atoms from five 3,5-dinitro­benzoate anions. On the other hand, each 3,5-dinitro­benzoate anion links five Rb cations with the carboxyl­ate groups as μ3-bridging. The metal atom is firstly linked by the carboxyl­ate groups into a chain along the c-axis direction, which is further linked by bonds between the Rb and nitro O atoms, giving a three-dimensional framework. PMID:21836829

Theoretical Prediction of the Heats of Formation, Densities, and Relative Sensitivities for 1,7-dinitro-3,4,5,8-tetra N-oxide-bis([1,2,3]triazolo)[4,5-b:5’,4’ e]pyrazine, 1,7-dinitro-3,5,8-tri N-oxide bis([1,2,3]triazolo)[4,5-b:5’,4’ e]pyrazine, 1,7-dinitro 3,5-bis N-oxide bis([1,2,3]triazolo)[4,5-b:5’,4’ e]pyrazine, 1,7-dinitro 1,7-dihydrobis([1,2,3]triazolo)[4,5-b:4’,5’-e]pyrazine

DTIC Science & Technology

2016-09-01

2 Fig. 2 Electrostatic potential map of 1, without a) and with b) molecule overlay...3 Fig. 3 Electrostatic potential map of 2, without a) and with b) molecule overlay...3 Fig. 4 Electrostatic potential map of 3, without a) and

Preparation and characterization of 3,5-dinitro-1H-1,2,4-triazole.

PubMed

Haiges, R; Bélanger-Chabot, G; Kaplan, S M; Christe, K O

2015-04-28

Neat 3,5-dinitro-1H-1,2,4-triazole was obtained in quantitative yield from potassium 3,5-dinitro-1,2,4-triazolate and sulfuric acid. The compound was purified by sublimation in vacuo at 110 °C. Pure HDNT is a hygroscopic white solid that is impact and friction sensitive and decomposes explosively upon heating to 170 °C. However, the presence of impurities might lower the decomposition temperature and increase the sensitivity of the material. Potassium 3,5-dinitro-1,2,4-triazolate was prepared from commercially available 3,5-diamino-4H-1,2,4-triazole with sodium nitrite and sulfuric acid. The synthesis of HDNT from 2-cyanoguanidine and hydrazine hydrate without isolation and purification of the 3,5-diamino-4H-1,2,4-triazole intermediate can result in the formation of azidotriazole impurities. A triclinic and a monoclinic polymorph of 3,5-dinitro-1H-1,2,4-triazole were found by X-ray structure determination. In addition, the crystal structure of the hydrate (HDNT)3·4H2O, as well as those of several HDNT impurities and decomposition products were obtained.

Production of the ammonium salt of 3,5-dinitro-1,2,4-triazole by solvent extraction

DOEpatents

Lee, Kien Y.; Ott, Donald G.

1980-01-01

The ammonium salt of 3,5-dinitro-1,2,4-triazole has utility as a chemical explosive. In accordance with the present invention, it may readily be produced by solvent extraction using high-molecular weight, water-insoluble amines followed by amination with anhydrous ammonia gas. The aqueous reaction mixture produced in the synthesis of the parent compound, 3,5-dinitro-1,2,4-triazole, is quite suitable--and indeed is preferred--for use as the feed material in the process of the invention.

Some 1-(diorganooxyphosphonyl)methyl-2,4- and -2,6-dinitro-benzenes

NASA Technical Reports Server (NTRS)

Mikroyannidis, John A. (Inventor); Kourtides, Demetrius A. (Inventor)

1989-01-01

1-(Diorgano oxyphosphonyl) methyl) 2,4- and 2,6-dinitro- and diamino benzenes are prepared by nitrating an (organophosphonyl)methly benzene to produce the dinitro compounds which are then reduced to the diamino compounds. The organo group (alkyl, haloalkyl, aryl) on the phosphorus may be removed to give the free acids, (HO)2P(double bond O) single bond. The diamino compounds may be polymerized with dianhydrides or diacyl halides to produce fire and flame resistant polymers which are useful in the manufacture of aircraft structures.

Production of the ammonium salt of 3,5-dinitro-1,2,4-triazole by solvent extraction

DOEpatents

Lee, K.Y.; Ott, D.G.

1979-11-07

The ammonium salt of 3,5-dinitro-1,2,4-triazole has utility as a chemical explosive. In accordance with the present invention, it may readily be produced by solvent extraction using high-molecular weight, water-insoluble amines, followed by amination with anhydrous ammonia gas. The aqueous reaction mixture produced in the synthesis of the parent compound, 3,5-dinitro-1,2,4-triazole, is quite suitable - and indeed is preferred - for use as the feed material in the process of the invention.

Theoretical Prediction of the Heats of Formation, Densities, and Relative Sensitivities for 5,7-dinitro-5,7-diaza-1,3-dioxabicyclo (3:3:0)octan-2-one

DTIC Science & Technology

2016-04-01

dioxabicyclo(3:3:0)octan-2-one molecule .............................................1 Fig. 2 Electrostatic potential map of 5,7-dinitro-5,7-diaza-1,3...the impact sensitivities, the electrostatic maps on the 0.001 isosurfaces were generated with the scalar range of the electrostatic surface potential... Electrostatic potential map of 5,7-dinitro-5,7-diaza-1,3-dioxabicyclo(3:3:0)octan-2- one, a) with and b-c) without molecule overlay. Image c) shows the opposite

4,6-Dinitro-o-cyclohexyl phenol

Integrated Risk Information System (IRIS)

4,6 - Dinitro - o - cyclohexyl phenol ; CASRN 131 - 89 - 5 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments

Synergistic liquid-liquid extractive spectrophotometric determination of gold(III) using 1-(2',4'-dinitro aminophenyl)-4,4,6-trimethyl-1,4-dihydropyrimidine-2-thiol.

PubMed

Kamble, Ganesh S; Kolekar, Sanjay S; Han, Sung H; Anuse, Mansing A

2010-05-15

Synergistic liquid-liquid extractive spectrophotometric determination of gold(III) using 1-(2',4'-dinitro aminophenyl)-4,4,6-trimethyl-1,4-dihydro pyrimidine-2-thiol [2',4'-dinitro APTPT] has been described. Equal volumes (5cm(3)) of the 2',4'-dinitro APTPT (0.02molL(-1)) in the presence of pyridine (0.5molL(-1)) form an orange-red coloured ternary complex with gold(III) of molar ratio 1:1:1 at pH 1.8-2.4 with 5min of shaking. The absorbance of coloured organic layer in 1,2-dichloroethane is measured spectrophotometrically at 445nm against reagent blank. A pronounced synergism has been observed by the binary mixture of 2',4'-dinitro APTPT and pyridine, which shows that the enhancement in the absorbance is observed in the presence of pyridine by the adduct formation in the organic phase. Beer's law was obeyed in the concentration range 2.5-20.0microgmL(-1), with molar absorptivity and Sandell's sensitivity values of 8.7x10(3)dm(3)mol(-1)cm(-1) and 0.023microgcm(-2) respectively. A repetition of the method was checked by finding relative standard deviation (R.S.D.) (n=10) which was 0.17%. The composition of the gold(III)-2',4'-dinitro APTPT-pyridine adduct was established by slope analysis, molar ratio and Job's method. The ternary complex was stable for more than 48h. The influence of various factors such as pH, 2',4'-dinitro APTPT concentration, solvent and pyridine on the degree of complexation has been established. A number of foreign ions tested for their interferences and use of suitable masking agents wherever necessary are tabulated, which show that selectivity of the method has been enhanced. The method is successfully employed for the determination of gold(III) in binary, synthetic mixtures and ayurvedic samples. The reliability of the method is assured by inter-comparison of experimental values, using an atomic absorption spectrometer.

Preparation of 1,1'-dinitro-3,3'-azo-1,2,4-triazole

DOEpatents

Lee, Kien-Yin

1986-01-01

A new high density composition of matter, 1,1'-dinitro-3,3'-azo-1,2,4-triazole, has been synthesized using inexpensive, commonly available compounds. This compound has been found to be an explosive, and its use as a propellant is anticipated.

1-(2,4-Dinitro­phen­yl)-2-(1,2,3,4-tetra­hydro­naphthalen-1-yl­idene)hydrazine

PubMed Central

Danish, M.; Hamid, Masood; Tahir, M. Nawaz; Ahmad, Nazir; Ghafoor, Sabiha

2010-01-01

In the title compound, C14H14N4O4, the dihedral angle between the benzene rings is 10.42 (8)°. The nitro groups make dihedral angles of 5.3 (2) and 6.47 (15)° with their parent ring and are oriented at 11.2 (3)° with respect to each other. An intra­molecular N—H⋯O hydrogen bond completes an S(6) ring motif. In the crystal, mol­ecules are linked by C—H⋯O inter­actions, thus forming (010) chains in which R 2 2(13) ring motifs are present. There also exist aromatic π–π stacking inter­actions [centroid–centroid separation = 3.7046 (9) Å]. PMID:21588393

Synergistic extraction and spectrophotometric determination of copper(II) using 1-(2',4'-dinitro aminophenyl)-4,4,6-trimethyl-1,4-dihydropyrimidine-2-thiol: Analysis of alloys, pharmaceuticals and biological samples

NASA Astrophysics Data System (ADS)

Kamble, Ganesh S.; Kolekar, Sanjay S.; Anuse, Mansing A.

2011-05-01

A simple and selective spectrophotometric method was developed for the determination of copper(II) with 1-(2',4'-dinitro aminophenyl)-4,4,6-trimethyl-1,4-dihydropyrimidine-2-thiol [2',4'-dinitro APTPT] as a chromogenic reagent. The procedure was based on the synergistic extraction of copper(II) with 2',4'-dinitro APTPT in the presence of 0.5 mol L -1 pyridine to give green colored ternary complex of a molar ratio 1:2:2 (M:L:Py) in the pH range 8.7-10.5. It exhibits a maximum absorption of colored complex at 445 nm and 645 nm in chloroform against the reagent blank. Beer's law was followed in the concentration range 10-80 μg mL -1 of copper(II) and optimum range of 20-70 μg mL -1 the metal as evaluated from Ringbom's plot. The molar absorptivity and Sandell's sensitivity of copper(II)-2',4'-dinitro APTPT-pyridine complex in chloroform are 0.87 × 10 3 L mol -1 cm -1 and 0.072 μg cm -2, respectively. The interfering effects of various cations and anions were also studied, and use of suitable masking agents enhances the selectivity of the method. The proposed method is rapid, reproducible and successfully applied for the determination of copper(II) in binary and synthetic mixtures, alloys, pharmaceutical formulations, environmental and fertilizer samples. Comparison of the results with those obtained using an atomic absorption spectrophotometer also tested the validity of the method.

Crystal and Vibrational Structure of Energetic 3,5-dinitro 1,3,5-oxadiazinane (DOD) by Single Crystal X-ray Diffractometry and Raman Spectroscopy

DTIC Science & Technology

2018-03-19

calculations using a temperature of 298 K. 15. SUBJECT TERMS 3,5-dinitro-1,3,5-oxadiazinane (DOD), X-ray crystallography , Raman, energetic material...X-ray analysis. 2.2 Characterization X-ray Crystallography . DOD crystals were characterized with a SuperNova, Dualflex, EosS2 diffractometer using

Denitration of 2,4,6-trinitrotoluene in aqueous solutions using small-molecular-weight catalyst(s) secreted by Pseudomonas aeruginosa ESA-5.

PubMed

Stenuit, Ben; Eyers, Laurent; Rozenberg, Raoul; Habib-Jiwan, Jean-Louis; Matthijs, Sandra; Cornelis, Pierre; Agathos, Spiros N

2009-03-15

The denitration of 2,4,6-trinitrotoluene (TNT) can produce mono- or dinitro aromatic compounds susceptible to microbial mineralization. In the present study, denitration of TNT and other nitro aromatic compounds was investigated with a solid-phase extract obtained from the culture supernatant of Pseudomonas aeruginosa ESA-5 grown on a chemically defined aerobic medium. When the C18 solid-phase extract containing extracellular catalysts (EC) was incubated with TNT and NAD(P)H, we observed a significant release of nitrite. The concentration of nitrite released in the reaction medium was strongly dependent on the concentration of NAD(P)H and EC. Denitration also occurred with two TNT-related molecules, 2,4,6-trinitrobenzaldehyde, and 2,4,6-trinitrobenzyl alcohol. The release of nitrite was coupled with the formation of two polar metabolites, and mass spectrometry analyses indicated that each of these compounds had lost two nitro groups from the trinitro aromatic parent molecule. During this process, the production of toxic reduced TNT metabolites was minimal. The incubation of EC with TNT, NAD(P)H, and specific scavengers of reactive oxygen species suggested the involvement of superoxide radicals (O2*-) and hydrogen peroxide in the denitration process. Results obtained in this study reveal for the first time that extracellular small-molecular-weight substance(s) of bacterial origin can serve as green catalyst(s) to initiate TNT denitration. In addition, this study gives clear evidence for the production of a TNT metabolite bearing a single nitro groupfollowing a denitration reaction with catalyst(s) of biotic origin.

A Process for Preparing 1,3-Diamino-5-Pentafluorosulfanylbenzene and Polymers Therefrom

NASA Technical Reports Server (NTRS)

St.clair, Anne K. (Inventor); St.clair, Terry L. (Inventor); Thrasher, Joseph S. (Inventor)

1991-01-01

Diamines have shown their utility in the formation of many polymers. Examples of these polymers include polyimides, polyamides, and epoxies. The properties of these polymers are often dependent on the diamine which is used to make the polymer. By the present invention, a process was developed to make a diamine containing pentafluorosulfanylbenzene moiety. This process involves two steps: the preparation of a dinitro precursor and the reduction of the dinitro compound to form the diamine. This diamine was then reacted with various dianhydrides, diacidchlorides, and epoxy resins to yield the corresponding polyimide, polyamide, and epoxy polymers. These polymers were then used to make films, a wire coating enamel, and a semi-permeable membrane. The novelty of this invention resides in the process to make the diamine. Traditionally, dinitro compounds are reduced with hydrazine or a catalyst such as palladium on charcoal. The catalyst which is used in this invention is platinum oxide. When this catalyst is used, it makes it possible to form a polymer-grade diamine.

Theoretical Prediction of the Heats of Formation, Densities and Relative Sensitivities, and/or Synthetic Approaches Toward the Synthesis of High Energy Dense Materials (HEDMs): 3,5-Dinitro-1,3,5-Oxadiazinane, Bis-Adjacent RDX, Bis-Adjacent HMX, 4,4’,6,6’-Tetranitro-1,1’-Bis(N-oxide)-5,5’,6,6’-4H,4’H-5,5’-Bisimidazo Oxadiazole, and the Open-Cage Derivative of CL-20

DTIC Science & Technology

2015-09-01

HMX , 4,4’,6,6’- Tetranitro-1,1’-Bis(N-oxide)-5,5’,6,6’-4H,4’H- 5,5’-Bisimidazo Oxadiazole, and the Open- Cage Derivative of CL-20...HEDMs): 3,5-Dinitro-1,3,5-Oxadiazinane, Bis-Adjacent RDX, Bis-Adjacent HMX , 4,4’,6,6’- Tetranitro-1,1’-Bis(N-oxide)-5,5’,6,6’-4H,4’H- 5,5’-Bisimidazo...Materials (HEDMs): 3,5-Dinitro-1,3,5-Oxadiazinane, Bis-Adjacent RDX, Bis-Adjacent HMX , 4,4’,6,6’-Tetranitro-1,1’-Bis(N-oxide)-

Stereochemistry of quinoxaline antagonist binding to a glutamate receptor investigated by Fourier transform infrared spectroscopy.

PubMed

Madden, D R; Thiran, S; Zimmermann, H; Romm, J; Jayaraman, V

2001-10-12

The stereochemistry of the interactions between quinoxaline antagonists and the ligand-binding domain of the glutamate receptor 4 (GluR4) have been investigated by probing their vibrational modes using Fourier transform infrared spectroscopy. In solution, the electron-withdrawing nitro groups of both compounds establish a resonance equilibrium that appears to stabilize the keto form of one of the cyclic amide carbonyl bonds. Changes in the 6,7-dinitro-2,3-dihydroxyquinoxaline vibrational spectra on binding to the glutamate receptor, interpreted within the framework of a published crystal structure, illuminate the stereochemistry of the interaction and suggest that the binding site imposes a more polarized electronic bonding configuration on this antagonist. Similar spectral changes are observed for 6-cyano-7-dinitro-2,3-dihydroxyquinoxaline, confirming that its interactions with the binding site are highly similar to those of 6,7-dinitro-2,3-dihydroxyquinoxaline and leading to a model of the 6-cyano-7-dinitro-2,3-dihydroxyquinoxaline-S1S2 complex, for which no crystal structure is available. Conformational changes within the GluR ligand binding domain were also monitored. Compared with the previously reported spectral changes seen on binding of the agonist glutamate, only a relatively small change is detected on antagonist binding. This correlation between the functional effects of different classes of ligand and the magnitude of the spectroscopic changes they induce suggests that the spectral data reflect physiologically relevant conformational processes.

Derivatization of amino acids with N,N-dimethyl-2,4-dinitro-5-fluorobenzylamine for liquid chromatography/electrospray ionization mass spectrometry.

PubMed

Liu, Zhongfa; Minkler, Paul E; Lin, De; Sayre, Lawrence M

2004-01-01

Derivatization, separation and identification of amino acids with a novel compound, N,N-dimethyl-2,4-dinitro-5-fluorobenzylamine (DMDNFB), using high-performance liquid chromatography/electrospray ionization mass spectrometry (HPLC/ESI-MS) was demonstrated. Compared to derivatization with 2,4-dinitrofluorobenzene (DNFB), DMDNFB-derivatized amino acids and dipeptides exhibit much larger ion current signals in the commonly used ESI positive mode, which was attributed to the introduction of the N,N-dimethylaminomethyl protonatable site. Copyright 2004 John Wiley & Sons, Ltd.

Theoretical Prediction of the Heat of Formation, Density, and Relative Sensitivity for 3,7-dinitro-[1,2,4]triazolo[5,1-c][1,2,4] triazin-4-amine

DTIC Science & Technology

2015-06-01

the procedures used to generate this information, as well as Cheetah calculations using the predicted crystalline density and heat of formation. 15...overlay ...............6 List of Tables Table Cheetah -predicted properties of the 3,7-dinitro-[1,2,4]triazolo[5,1- c][1,2,4]triazin-4-amine molecule...script, initially written for the ARL DSRC. Dr Rice is acknowledged for running the Cheetah calculations. All computations were performed at the ARL

Preparation of SRN1-type coupling adducts from aliphatic gem-dinitro compounds in ionic liquids.

PubMed

Kamimura, Akio; Toyoshima, Seiichi

2012-04-25

S(RN)1-type coupling adducts are readily prepared by the reaction between a-sulfonylesters or a-cyanosulfones and gem-dinitro compounds in ionic liquids. The reactions progress smoothly and recovered ionic liquids can be used for several iterations, as long as they are washed with water to remove alkali metallic salts. The reaction rate is slower than the corresponding S(RN)1 reaction in DMSO, but no acceleration on irradiation or no inhibition in the presence of m-DNB are observed.

The 1-((diorganooxyphosphonyl)-methyl)-2,4- and -2,6-diamido benzenes

NASA Technical Reports Server (NTRS)

Mikroyannidis, John A. (Inventor); Kourtides, Demetrius A. (Inventor)

1989-01-01

1-((Diorgano oxyphosphonyl) methyl)-2,4- and -2,6-dinitro and diamino benzenes are prepared by nitrating an (organophosphonyl) methyl benzene to produce the dinitro compounds which are then reduced to the diamino compounds. The organo grounds (alkyl, haloalkyl, aryl) on the phosphorus may be removed to give the free acids (HO)2P(double bond O)single bond. The diamino compounds may be polymerized with dianhydrides or diacyl halides to produce fire and flame resistant polymers which are useful in the manufacture of aircraft structures.

The 1-((diorganooxy phosphonyl) methyl)-2,4- and -2,6-diamino benzenes and their derivatives

NASA Technical Reports Server (NTRS)

Mikroyannidis, John A. (Inventor); Kourtides, Demetrius A. (Inventor)

1987-01-01

The 1-((diorganooxy phosphonyl) methyl)-2,4- and -2,6-dinitro- and diamino benzenes are prepared by nitrating an (organo phosphenyl) methyl benzene to produce the dinitro compounds which are then reduced to the diamino compounds. The organo groups (alkyl, haloalkyl, aryl) on the phosphorus may be removed to give the free acids (HO)2P(=0)-. The diamino compounds may be polymerized with dianhydrides or diacyl halides to produce fire and flame resistant polymers which are useful in the manufacture of aircraft structures.

Development of an reliable analytical method for synergistic extractive spectrophotometric determination of cobalt(II) from alloys and nano composite samples by using chromogenic chelating ligand

NASA Astrophysics Data System (ADS)

Kamble, Ganesh S.; Ghare, Anita A.; Kolekar, Sanjay S.; Han, Sung H.; Anuse, Mansing A.

2011-12-01

A synergistic simple and selective spectrophotometric method was developed for the determination of cobalt(II) with 1-(2',4'-dinitro aminophenyl)-4,4,6-trimethyl-1,4-dihydropyrimidine-2-thiol [2',4'-dinitro APTPT] as a chromogenic reagent. The proposed method has been described on the basis of synergistic effective extraction of cobalt(II) in presence of pyridine at pH range 9.5-10.2, showed orange-red coloured ternary complex having molar ratio 1:2:2 (M:L:Py). The equilibrium time is 10 min for extraction of cobalt(III) from organic phase. The absorbance of coloured organic layer in chloroform is measured spectrophotometrically at 490 nm against reagent blank. The Beer's law was obeyed in the concentration range 2.5-15 μg mL -1 of cobalt(II) and optimum concentration range was 5-12.5 μg mL -1 of cobalt(II) and it was evaluated from Ringbom's plot. The molar absorptivity and Sandell's sensitivity of cobalt(II)-2',4'-dinitro APTPT-pyridine complex in chloroform are 1.109 × 10 3 L mol -1 cm -1 and 0.053 μg cm -2, respectively while molar absorptivity and Sandell's sensitivity of cobalt(II)-2',4'-dinitro APTPT complex in chloroform are 6.22 × 10 2 L mol -1 cm -1 and 0.096 μg cm -2, respectively. The composition of cobalt(II)-2',4'-dinitro APTPT-pyridine complex (1:2:2) was established by slope ratio method, mole ratio method and Job's method of continuous variation. The ternary complex was stable for more than 48 h. The interfering effects of various cations and anions were also studied, and use of suitable masking agents enhances the selectivity of the method. The method is successfully applied for the determination of cobalt(II) in binary, synthetic mixtures and real samples. A repetition of the method was checked by finding relative standard deviation (R.S.D.) for n = 5 which was 0.15%. The reliability of the method is confirmed by comparison of experimental results with atomic absorption spectrophotometer.

Sodium hypochlorite as an alternative to hydrogen peroxide in Fenton process for industrial scale.

PubMed

Behin, Jamshid; Akbari, Abbas; Mahmoudi, Mohsen; Khajeh, Mehdi

2017-09-15

In present work, the treatment of aromatic compounds of simulated wastewater was performed by Fenton and NaOCl/Fe 2+ processes. The model solution was prepared based on the wastewater composition of Diisocyanate unit of Karoon Petrochemical Company/Iran containing Diamino-toluenes, Nitro-phenol, Mononitro-toluene, Nitro-cresol, and Dinitro-toluene. Experiments were conducted in a batch mode to examine the effects of operating variables such as pH, oxidant dosages, ferrous ion concentration and numbers of feeding on COD removal. Taguchi experimental design was used to determine the optimum conditions. The COD removal efficiency under optimum conditions (suggested by Taguchi design) in Fenton and NaOCl/Fe 2+ processes was 88.7% and 83.4%, respectively. The highest contribution factor in Fenton process belongs to pH (47.47%) and in NaOCl/Fe 2+ process belongs to NaOCl/pollutants (50.26%). High regression coefficient (R 2 : 0.98) obtained for Taguchi method, indicates that models are statistically significant and are in well agreement with each other. The NaOCl/Fe 2+ process utilizing a conventional oxidant, in comparison to hydrogen peroxide, is an efficient cost effective process for COD removal from real wastewater, although the removal efficiency is not as high as in Fenton process; however it is a suitable process to replace Fenton process in industrial scale for wastewater involved aromatic compounds with high COD. This process was successfully applied in Karoon Petrochemical Company/Iran. Copyright © 2017 Elsevier Ltd. All rights reserved.

Solubility Report of 1-Methyl-3,5-Dinitro-1H-1,2,4-Triazole (MDNT) and 2-Methyl-4,5-Dinitro-2H-1,2,3-Triazole 1-Oxide (MDNTO) for Co-Crystallization Screen

DTIC Science & Technology

2015-11-01

New Co-Crystals,” Crystal Growth & Design, Vol. 9, No. 3, pp. 1531-1537, 2009. 2 Landenberger, K., Matzger, A., “ Cocrystal Engineering of a...Y., Li, H., Zhou, Y., Zhou, J., Geo, T., Zhang, H., Jiang, G., “Toward Low- Sensitive and High-Energetic Cocrystal 1: Evaluation of the Power and the...Safety of Observed Energetic Cocrystals ,” CrystEngComm, 15, 4003-4014, 2013. 4 Levinthal, M.L., “Propellant Made With Cocrystals of

Solvatochromic studies on 4-Bromomethyl-7-methyl coumarins

NASA Astrophysics Data System (ADS)

Khanapurmath, Netravati; Kulkarni, Manohar V.; Pallavi, L.; Yenagi, Jayashree; Tonannavar, Jagdish

2018-05-01

Non- and dinitro 4-bromomethyl-7-methyl coumarins and new mono- and trinitro 4-bromomethyl-7-methyl coumarins have been synthesized. Effect of nitro groups on the photophysical properties of the parent 4-bromomethyl-7-methyl coumarin has been reported. Their ground and excited state dipole moments have been estimated by solvatochromic method using nine solvents. A reasonable agreement has been observed between calculated and observed dipole moments. Reduction in dipole moment has been observed for mono- and dinitro compounds where as the trinitro compound was found to have higher dipole moment in the excited state.

Superior Energetic Materials that Contain Carbocations and Anions. Energetic Materials Restricted in Composition to C, H, N, and O Atoms

DTIC Science & Technology

1993-10-30

AMXRO-IP-Library. Summary Thiourea condensed with 1,4-diformnyl-2,3,5,6-tetrahydroxypiperazine 14 in the presence of 3 hydrochloric acid to give 2,6...b:4’,5"-e]pyrazine 20 to 2- oxo-2,3-dihydro-1,3-dinitro-lH-imidazo[4,5-b]pyrazine 21 was brought about by hydrochloric acid . Treatment with lithium...reaction with tert-butyl amine, and converted to 4,8-dihydro-4,8-dinitro- 1H,5H-diimidazo[4,5-b:4’,5’-e]pyrazine-2,6-disulfonic acid 17 by nitric acid

Synthesis, and spectroscopic studies of charge transfer complex of 1,2-dimethylimidazole as an electron donor with π-acceptor 2,4-dinitro-1-naphthol in different polar solvents

NASA Astrophysics Data System (ADS)

Miyan, Lal; Khan, Ishaat M.; Ahmad, Afaq

2015-07-01

The charge transfer (CT) complex of 1,2-dimethylimidazole (DMI) as an electron donor with π acceptor 2,4-dinitro-1-naphthol (DNN) has been studied spectrophotometrically in different solvents like chloroform, acetonitrile, methanol, methylene chloride, etc. at room temperature. The CT complex which is formed through the transfer of lone pair electrons from DMI to DNN exhibits well resolved CT bands and the regions of these bands were remarkably different from those of the donor and acceptor. The stoichiometry of the CT complex was found to be 1:1 by a straight-line method between donor and acceptor with maximum absorption bands. The novel CT complex has been characterized by FTIR, TGA-DTA, powder XRD, 1H NMR and 13C NMR spectroscopic techniques. The Benesi-Hildebrand equation has been used to determine the formation constant (KCT), molar extinction coefficient (εCT), standard gibbs free energy (ΔG°) and other physical parameters of the CT complex. The formation constant recorded higher values and molar extinction coefficient recorded lower values in chloroform compared with methylene chloride, methanol and acetonitrile, confirming the strong interaction between the molecular orbital's of donor and acceptor in the ground state in less polar solvent. This CT complex has been studied by absorption spectra of donor 1,2-dimethylimidazole (DMI) and acceptor 2,4-dinitro-1-naphthol (DNN) by using the spectrophotometric technique in various solvents at room temperature.

Nitration of particle-associated PAHs and their derivatives (nitro-, oxy-, and hydroxy-PAHs) with NO 3 radicals

NASA Astrophysics Data System (ADS)

Zhang, Yang; Yang, Bo; Gan, Jie; Liu, Changgeng; Shu, Xi; Shu, Jinian

2011-05-01

The heterogeneous reactions of typical polycyclic aromatic hydrocarbons (PAHs) and their derivatives (nitro-, oxy-, and hydroxy-PAHs) adsorbed on azelaic acid particles with NO 3 radicals are investigated using a flow-tube reactor coupled to a vacuum ultraviolet photoionization aerosol time-of-flight mass spectrometer (VUV-ATOFMS). The mono-nitro-, di-nitro-, and poly-nitro-products from successive nitro-substitution reactions of PAHs and their derivatives are observed in real time with VUV-ATOFMS. 9-Nitroanthracene, anthraquinone, anthrone, 9,10-dinitroanthracene, 2-, 4-, and 9-nitrophenanthrene, 1-nitropyrene, 1,3-, 1,6-, and 1,8-dinitropyrene, 7-nitrobenzo[ a]anthracene, and benzo[ a]anthracene-7,12-dione are identified by GC/MS analysis of the reaction products of PAHs and their derivatives coated on the inner bottom surface of the conical flasks with NO 3 radicals. Other oxygenated products are tentatively assigned. 1-Nitropyrene is the only mono-nitrated product detected in the reaction of surface-bound pyrene with gas-phase NO 3 radicals. This phenomenon is different from what has been observed in previous studies of the gas-phase pyrene nitration, showing that 2-nitropyrene is the sole nitration product. The experimental results may reveal the discrepancies between the heterogeneous and homogeneous nitrations of pyrene.

Interaction Between Cytochrome c and the Hapten 2,4-Dinitro-fluorobenzene by Electrospray Ionization Mass Spectrometry

NASA Astrophysics Data System (ADS)

Wu, Bo; Chu, Yan-qiu; Dai, Zhao-yun; Ding, Chuan-fan

2008-06-01

Allergic contact dermatitis is a delayed hypersensitivity reaction, which results from skin exposure to low molecular weight chemicals such as haptens. To clarify the pathogenic mechanism, electrospray ionization mass spectrometry (ESI-MS) and hydrogen/deuterium (H/D) exchange, as well as UV spectroscopy, were applied to determine the interaction between the model protein cytochrome c (cyt c) and the hapten 2,4-dinitro-fluorobenzene (DNFB). The ESI-MS results demonstrate that the conformation of cyt c can change from native folded state into partially unfolded state with the increase of DNFB. The equilibrium state H/D exchange followed by ESI-MS further confirms the above results. UV spectroscopy indicates that the strong-field coordination between iron of heme (prosthetic group) and His18 or Met80 of cyt c is not obviously affected by the hapten.

Detonating an insensitive explosive

DOEpatents

Lee, Kien-yin; Storm, Carlyle B.

1992-01-01

A method for making 3-amino-5-nitro-1,2,4-triazole using ammonium 3,5-dinitro-1,2,4-triazole and hydrazine hydrate as starting materials and a method for providing energy derived from 3-amino-5-nitro-1,2,4-triazole.

Hydrogen bonded 2-methyl-1H-imidazol-3-ium 3,5-dinitrobenzoate 3,5-dinitrobenzoic acid, a new optical crystal: Evaluation of properties by structural, spectral, quantum chemical calculations, Z-scan and Hirshfeld studies

NASA Astrophysics Data System (ADS)

Sathya, K.; Dhamodharan, P.; Dhandapani, M.

2018-03-01

A new hydrgen bonded proton transfer complex, 2-methyl imidazolium 3, 5-dinitrobenzoate 3,5-dinitro benzoic acid (MIDB) was synthesized by the reaction between 2-methyl imidazole with 3,5-dinitro benzoic acid (1:2) in methanol solvent at room temperature. The crystals were subjected to FT-IR spectral analysis to confirm the functional groups of the new compound. Single crystal XRD analysis reveals that MIDB belongs to monoclinic system with P21/c space group. The asymmetric unit consists of one 2-methyl imidazolium cation, one 3, 5-dinitrobenzoate anion and one uncharged 3,5-dinitro benzoic acid moiety. Experimental NMR spectroscopic data and theoretically calculated NMR data correlated very well to estabilish the exact carbon skeleton and hydrogen environment in the molecular structure of MIDB. The thermal stability of the compound was investigated by thermogravimetry and differential thermal analysis (TG-DTA). Computational studies such as optimization of molecular geometry, natural bond analysis (NBO), Mulliken population analysis and HOMO-LUMO analysis were performed using Gaussian 09 software by B3LYP method at 6-31 g basis set level. The calculated first-order polarizability (β) of MIDB from computational studies is 4.1752 × 10-30 esu, which is 32 times greater than that of urea. UV-vis-NIR spectral studies revealed that the MIDB has a large optical transparency window. The optical nonlinearities of MIDB have been investigated by Z-scan technique with Hesbnd Ne laser radiation of wavelength 632.8 nm. Hirshfeld analysis indicate O⋯H/H⋯O interactions are the superior interactions confirming excessive hydrogen bond net work in the molecular structure.

Monitoring of environmental exposure to polycyclic aromatic hydrocarbons: a review.

PubMed

Srogi, K

2007-01-01

Polycyclic aromatic hydrocarbons (PAHs) are a large group of organic compounds with two or more fused aromatic rings. They have a relatively low solubility in water, but are highly lipophilic. Most of the PAHs with low vapour pressure in the air are adsorbed on particles. When dissolved in water or adsorbed on particulate matter, PAHs can undergo photodecomposition when exposed to ultraviolet light from solar radiation. In the atmosphere, PAHs can react with pollutants such as ozone, nitrogen oxides and sulfur dioxide, yielding diones, nitro- and dinitro-PAHs, and sulfonic acids, respectively. PAHs may also be degraded by some microorganisms in the soil. PAHs are widespread environmental contaminants resulting from incomplete combustion of organic materials. The occurrence is largely a result of anthropogenic emissions such as fossil fuel-burning, motor vehicle, waste incinerator, oil refining, coke and asphalt production, and aluminum production, etc. PAHs have received increased attention in recent years in air pollution studies because some of these compounds are highly carcinogenic or mutagenic. Eight PAHs (Car-PAHs) typically considered as possible carcinogens are: benzo(a)anthracene, chrysene, benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(a)pyrene (B(a)P), dibenzo(a,h)anthracene, indeno(1,2,3-cd)pyrene and benzo(g,h,i)perylene. In particular, benzo(a)pyrene has been identified as being highly carcinogenic. The US Environmental Protection Agency (EPA) has promulgated 16 unsubstituted PAHs (EPA-PAH) as priority pollutants. Thus, exposure assessments of PAHs in the developing world are important. The scope of this review will be to give an overview of PAH concentrations in various environmental samples and to discuss the advantages and limitations of applying these parameters in the assessment of environmental risks in ecosystems and human health. As it well known, there is an increasing trend to use the behavior of pollutants (i.e. bioaccumulation) as well as pollution-induced biological and biochemical effects on human organisms to evaluate or predict the impact of chemicals on ecosystems. Emphasis in this review will, therefore, be placed on the use of bioaccumulation and biomarker responses in air, soil, water and food, as monitoring tools for the assessment of the risks and hazards of PAH concentrations for the ecosystem, as well as on its limitations.

40 CFR Appendix - Tables to Part 132

Code of Federal Regulations, 2012 CFR

2012-07-01

...-Bromophenyl phenyl ether Butyl benzyl phthalate Cadmium Carbon tetrachloride; tetrachloromethane Chlorobenzene...) phthalate Diazinon 1,2:5,6-Dibenzanthracene; dibenz[a,h]anthracene Dibutyl phthalate; di-n-butyl phthalate 1...-dichloropropylene Diethyl phthalate 2,4-Dimethylphenol; 2,4-xylenol Dimethyl phthalate 4,6-Dinitro-o-cresol; 2...

A simple spectrophotometric determination of meptyldinocap by its hydrolysis.

PubMed

Kurup, Sunita; Pillai, Ajai Kumar

2013-01-01

A simple spectrophotometric method is proposed for the determination of meptyldinocap (2,4-dinitro-6-octylphenyl crotonate). The method is based on the hydrolysis of meptyldinocap by hydroxylamine solution in alkaline medium to give 2,4-dinitro-6-octylphenol (2,4-DNOP), having maximum absorption at 380 nm. The reaction is found to be instantaneous in presence of ethanol. Beer's law is valid over the concentration range of 1.2-13 microg mL(-1) with molar absorptivity and Sandell's sensitivity of 3.22 x 10(6) L mol(-1) cm(-1) and 0.0001 microg cm(-2) respectively. The limit of detection and quantification were 0.0892 and 0.2703 microg mL(-1), respectively. The tolerance limits of interfering ions are discussed. All variables were studied in order to optimize the reaction conditions. The validity of the method was checked by its simultaneous determination in fruits and water samples and the results were statistically compared with those of a reference method by applying the Student's t-test and F-test.

Synthesis, optical properties and explosive sensing performances of a series of novel π-conjugated aromatic end-capped oligothiophenes.

PubMed

Liu, Taihong; Zhao, Keru; Liu, Ke; Ding, Liping; Yin, Shiwei; Fang, Yu

2013-02-15

Four novel terthiophene (3T) derivatives, have been synthesized by employing Grignard coupling reaction via end-capping of naphthyl (NA) or pyrenyl (Py) unit to the one or two ends of 3T. It has been shown that both increasing electron donating strength and extending conjugation are effective approaches to improve the photochemical stability of the oligothiophene. Fluorescence studies demonstrated that the emission of the 3T derivatives is sensitive to the presence of some important nitro-containing explosives in their ethanol solution, in particular, 2,4,6-trinitrophenol (PA) and 3,5-dinitro-2,6-bispicrylamino pyridine (PYX). As an example, the detection limits of 4 to PA and PYX were determined to be 6.21 × 10(-7)mol/L and 8.95 × 10(-7)mol/L, respectively. Based on the discovery, a colorimetric detection method has been developed. The sensitive and selective response of the modified 3T to the explosives have been tentatively attributed to the adsorptive affinity of the compounds to the explosives, and to the higher probability of the electron transfer from the electron-rich 3T derivatives to the electron-poor nitro-containing explosives. No doubt, present study broadens the family of fluorophores which may be employed for the development of fluorescent sensors. Copyright © 2012 Elsevier B.V. All rights reserved.

Urinary 1-hydroxypyrene and mutagenicity in bus drivers and mail carriers exposed to urban air pollution in Denmark.

PubMed

Hansen, Ase Marie; Wallin, Håkan; Binderup, Mona Lise; Dybdahl, Marianne; Autrup, Herman; Loft, Steffen; Knudsen, Lisbeth Ehlert

2004-01-10

Previous studies in Denmark have shown that bus drivers and tramway employees were at an increased risk for developing several types of cancer and that bus drives from central Copenhagen have high levels of biomarkers of DNA damage. The present study evaluates 1-hydroxypyrene concentrations and mutagenic activity in urine as biomarkers of exposure in non-smoking bus drivers in city and rural areas on a work day and a day off and in non-smoking mail carriers working outdoors (in the streets) and indoors (in the office). Twenty-four hour urine samples were collected on a working day and a day off from 60 non-smoking bus drivers in city and rural areas and from 88 non-smoking mail carriers working outdoors (in the streets) and indoors (in the office). The concentration of 1-hydroxypyrene was measured by means of HPLC and the mutagenic activity was assessed by the Ames assay with Salmonella tester strain YG1021 and S9 mix. The N-acetyltransferase (NAT2) phenotype was used as a biomarker for susceptibility to mutagenic/carcinogenic compounds. Bus drivers excreted more 1-hydroxypyrene in urine than did mail carriers. The differences were slightly smaller when NAT2 phenotype, cooking at home, exposure to vehicle exhaust, and performing physical exercise after work were included. The NAT2 slow acetylators had 29% (1.29 [CI: 1.15-1.98]) higher 1-hydroxypyrene concentrations in urine than the fast acetylators. Male bus drivers had 0.92 revertants/mol creatinine [CI: 0.37-1.47] and female bus drivers 1.90 revertants/mol creatinine [CI: 1.01-2.79] higher mutagenic activity in urine than mail carriers. The present study indicates that bus drivers are more exposed to polycyclic aromatic hydrocarbons (PAH) and mutagens than mail carriers. Mail carriers who worked outdoors had higher urinary concentration of 1-hydroxypyrene, a marker of exposure to PAH, than those working indoors. The individual levels of urinary mutagenic activity were not correlated to excretion of 1-hydroxypyrene. This might be due to the fact that the most potent mutagenic compounds in diesel exhaust are not PAH but dinitro-pyrenes. Among bus drivers, fast NAT2 acetylators had higher mutagenic activity in urine than slow NAT2 acetylators and female bus drivers had higher mutagenic activity than male bus drivers.

Pendimethalin Nitroreductase Is Responsible for the Initial Pendimethalin Degradation Step in Bacillus subtilis Y3

PubMed Central

Ni, Hai-yan; Wang, Fei; Li, Na; Yao, Li; Dai, Chen; He, Qin; He, Jian

2016-01-01

ABSTRACT Pendimethalin [N-(1-ethylpropyl)-2,6-dinitro-3,4-xylidine] is a selective preemergence dinitroaniline herbicide. Several fungi and bacteria have been reported to degrade pendimethalin, but the enzymes or genes involved in this process have not been characterized. Nitroreduction is the initial degradation and detoxification step for pendimethalin. In this study, a pendimethalin nitroreductase (PNR), responsible for the nitroreduction of pendimethalin, was purified from the pendimethalin-degrading strain Bacillus subtilis Y3. Based on a comparison of its mass fingerprints with all of the deduced proteins from the draft genome of strain Y3, a protein annotated as a nitroreductase was identified, and its corresponding encoding gene was termed pnr. PNR was a functional homodimer with a subunit molecular mass of approximately 23 kDa. PNR reduced the C-6 nitro group of the aromatic ring of pendimethalin, yielding 2-nitro-6-amino-N-(1-ethylpropyl)-3,4-xylidine. PNR could also catalyze the nitroreduction of three other major varieties of dinitroaniline herbicides, including butralin, oryzalin, and trifluralin. However, the number of reduced nitro groups was two instead of one, which differed from the nitroreduction of pendimethalin by PNR and which may be due to the symmetry in the chemical structures of the two nitro groups. A detoxification assay revealed that 2-nitro-6-amino-N-(1-ethylpropyl)-3,4-xylidine (PNR-reduced pendimethalin) showed no inhibitory effect on the growth of Saccharomyces cerevisiae BY4741, whereas pendimethalin showed an obvious inhibitory effect on its growth, indicating the detoxification effect of pendimethalin by PNR. Therefore, PNR has potential in pendimethalin detoxification applications. This report describes an enzyme (and corresponding gene) involved in the biodegradation of pendimethalin and dinitroaniline herbicides. IMPORTANCE Pendimethalin [N-(1-ethylpropyl)-2,6-dinitro-3,4-xylidine] is a widely used selective preemergence dinitroaniline herbicide, and its residue has been frequently detected in the environment. The U.S. Environmental Protection Agency (EPA) has classified pendimethalin as a persistent bioaccumulative toxin. To date, no enzymes or genes involved in pendimethalin biodegradation have been reported. In the present study, the gene pnr, which encodes the nitroreductase PNR, responsible for the nitroreduction of pendimethalin, was cloned from the pendimethalin-degrading strain Bacillus subtilis Y3. PNR could also catalyze the nitroreduction of three other major varieties of dinitroaniline herbicides, including butralin, oryzalin, and trifluralin. The reduction of pendimethalin by PNR might eliminate its toxicity against Saccharomyces cerevisiae BY4741, indicating the application potential of PNR in the detoxification of pendimethalin. PMID:27694234

40 CFR 180.574 - Fluazinam; tolerances for residues.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 24 2011-07-01 2011-07-01 false Fluazinam; tolerances for residues... § 180.574 Fluazinam; tolerances for residues. (a) General. (1) Tolerances are established for residues of fluazinam (3-chloro-N-[3-chloro-2,6-dinitro-4-(trifluoromethyl)phenyl]-5-(trifluoromethyl)-2...

Simulating the Transport and Fate of Trifluralin in Soil

Treesearch

Ying Ouyang; Jia-En Zhang; Li Hua Cui; Peter Nkedi-Kizza

2012-01-01

Understanding herbicide dynamics in agricultural soils is crucial to evaluate herbicide application efficiency and its environmental consequences. A model for herbicide trifluralin (α,α,α-reifluoro-2,6-dinitro-N,N-dipropyl-ρtoluidine) dynamics namely runoff, erosion, leaching, volatilization, and degradation losses in agricultural...

Increasing Fire Safety of Epoxies

NASA Technical Reports Server (NTRS)

Kourtides, D. A.; Mikroyannidis, J. A.

1985-01-01

Epoxy with increased resistance to fire made by reacting any of three commercial epoxide monomers with curing agent consisting of mixture of isomers called "DCEPD". Curing agent incorporates phosphorus and chlorine directly into crosslinking part of polymer. DCEPD produced by nitrating precursor phosphonylmethyl benzene, then reducing resulting isomeric mixture of dinitro compounds.

THE SOLVENT EXTRACTION OF NITROSYLRUTHENIUM BY TRILAURYLAMINE IN NITRATE SYSTEM. Summary Report for the Period, July 1, 1960 to March 31, 1962

DOE Office of Scientific and Technical Information (OSTI.GOV)

Skavdahl, R.E.; Mason, E.A.

1962-06-01

An investigation of the solvent extraction characteristics of the nitro and nitrato complexes of nitrosylruthenium in nitric acid- sodium nitrate aqueous media was conducted. As the organic extractant phase, a solution of trilaurylamine (TLA) in toluene was utilized. In addition to the usual process parameter variation tyne of experiment, a rapid dilution type of experiment was used extensively to determine qualitative and semiquantitative results regarding the degree of extractability and concentration of the more extractable species of the nitrato complexes of nitrosylruthenium. It was found that the acids of the tetra-nitrato and pentanitrato complexes were the more extractable species formore » that set of complexes and that the acid of the penta-nitrato complex was the more extractable of the two. It was observed that for freshly prepared solutions, the dinitro complex of nitrosylruthenium was much more extractable than the gross nitrato complexes solutions. Nitro complexes in general, and the dinitro complex in particular, may be the controlling agent in ruthenium decontamination of spent nuclear fuel processed by solvent extraction methods. The experimental results from both sets of complexes could be more meaningfully correlated on the basis of unbound nitric acid concentration in the organic phase than on the basis of nitric acid concentration in the aqueous phase. The extraction of nitric acid by TLA from nitric acid-sodium nitrate aqueous solutions was investigated and the results correlated on the basis of activity of the undissociated nitric acid in the aqueous phase. (auth)« less

Synthesis and Free Radical Scavenging Activity of New Hydroxybenzylidene Hydrazines.

PubMed

Sersen, Frantisek; Gregan, Fridrich; Kotora, Peter; Kmetova, Jarmila; Filo, Juraj; Loos, Dusan; Gregan, Juraj

2017-05-29

Hydroxybenzylidene hydrazines exhibit a wide spectrum of biological activities. Here, we report synthesis and free radical scavenging activity of nine new N-(hydroxybenzylidene)-N'-[2,6-dinitro-4-(trifluoromethyl)]phenylhydrazines. The chemical structures of these compounds were confirmed by 1H-NMR, 13C-NMR, 19F-NMR, IR spectroscopy, LC-MS, and elemental analysis. The prepared compounds were tested for their activity to scavenge 2,2-diphenyl-1-picrylhydrazyl (DPPH), galvinoxyl radical (GOR), and 2,2'-azino-bis(3-ethylbenzothiazoline)-6-sulphonic acid (ABTS) radicals. The free radical scavenging activity expressed as SC50 values of these compounds varied in a wide range, from a strong to no radical scavenging effect. The most effective radical scavengers were hydroxybenzylidene hydrazines containing three hydroxyl groups in the benzylidene part of their molecules. The prepared compounds were also tested for their activity to inhibit photosynthetic electron transport in spinach chloroplasts. IC50 values of these compounds varied in wide range, from an intermediate to no inhibitory effect.

Differential levels of metabolites and enzymes related to aroma formation in aromatic indica rice varieties: comparison with non-aromatic varieties.

PubMed

Ghosh, Puja; Roychoudhury, Aryadeep

2018-01-01

Accounting for aroma production in different aromatic indica rice varieties based on variations in the levels of concerned metabolites and enzymes is poorly explored. The present investigation was, therefore, focused on unraveling the differential levels of metabolites and activities of enzymes related to aroma formation in eleven indigenous aromatic rice varieties, as compared with four non-aromatic varieties. The levels of metabolites such as proline (Pro) and Δ 1 -pyrroline-5-carboxylate (P5C), and the activity of related enzymes such as proline dehydrogenase (PDH), Δ 1 -pyrroline-5-carboxylate synthetase (P5CS), and ornithine aminotransferase (OAT) were comparatively higher in the aromatic varieties, with Kalonunia and Tulaipanji registering the highest Pro, Kalonunia the highest P5C content, Gobindobhog with the highest PDH activity, Gobindobhog and Tulaipanji with the highest P5CS, and Pusa Basmati-1 with the highest OAT activity. The levels of putrescine (Put) and γ-aminobutyric acid (GABA) were comparatively lower in aromatic varieties, with concomitant higher diamine oxidase (DAO) activity, especially in the varieties Gobindobhog and Tulaipanji. The betaine-aldehyde dehydrogenase 2 (BADH2) enzyme activity was remarkably lesser in aromatic varieties, especially Radhunipagal and Gobindobhog. Though the metabolites such as glycine-betaine and higher polyamines such as spermidine and spermine showed no specific trend with respect to their quantitative level in either aromatic or non-aromatic varieties, they were notably lower in the aromatic varieties such as Gobindobhog, Kalonunia, and Tulaipanji, indicating a possibility of their involvement in aroma formation. Therefore, the levels of metabolites such as Pro, P5C and methylglyoxal (MG), and the activity of enzymes such as PDH, P5CS, OAT, and DAO were comparatively higher in the aromatic rice varieties than the non-aromatic ones, whereas the levels of Put, GABA, and BADH2 were lower. Overall, the present study showed that there exist variations in the accumulations of such metabolites as well as differential activity of enzymes controlling their production, which altogether regulate generation of aroma in aromatic varieties.

Effects of Hurricane Katrina-Related Levee Failures on Wetland Sediments

DTIC Science & Technology

2008-09-01

80-84 209 1 Non-detects in IPET study and synthesis of USEPA data were handled by taking ½ reporting limit. 2 Presley et al. (2006) report geometric...2,2’-oxybis( 1 - Chloropropane ) 4,6-Dinitro-2- methylphenol Hexachlorobenzene 2,4,6-Trichlorophenol 4-Bromophenyl phenyl ether Hexachlorobutadiene...viii 1 Introduction

Development of a new analytical tool for assessing the mutagen 2-methyl-1,4-dinitro-pyrrole in meat products by LC-ESI-MS/MS.

PubMed

Molognoni, Luciano; Daguer, Heitor; de Sá Ploêncio, Leandro Antunes; Yotsuyanagi, Suzana Eri; da Silva Correa Lemos, Ana Lucia; Joussef, Antonio Carlos; De Dea Lindner, Juliano

2018-08-01

The use of sorbate and nitrite in meat processing may lead to the formation of 2-methyl-1,4-dinitro-pyrrole (DNMP), a mutagenic compound. This work was aimed at developing and validating an analytical method for the quantitation of DNMP by liquid chromatography-tandem mass spectrometry. Full validation was performed in accordance to Commission Decision 2002/657/EC and method applicability was checked in several samples of meat products. A simple procedure, with low temperature partitioning solid-liquid extraction, was developed. The nitrosation during the extraction was monitored by the N-nitroso-DL-pipecolic acid content. Chromatographic separation was achieved in 8 min with di-isopropyl-3-aminopropyl silane bound to hydroxylated silica as stationary phase. Samples of bacon and cooked sausage yielded the highest concentrations of DNMP (68 ± 3 and 50 ± 3 μg kg -1 , respectively). The developed method proved to be a reliable, selective, and sensitive tool for DNMP measurements in meat products. Copyright © 2018 Elsevier B.V. All rights reserved.

Ammonium nitrate explosive systems

DOEpatents

Stinecipher, Mary M.; Coburn, Michael D.

1981-01-01

Novel explosives which comprise mixtures of ammonium nitrate and an ammonium salt of a nitroazole in desired ratios are disclosed. A preferred nitroazole is 3,5-dinitro-1,2,4-triazole. The explosive and physical properties of these explosives may readily be varied by the addition of other explosives and oxidizers. Certain of these mixtures have been found to act as ideal explosives.

Attempted Synthesis of 1,4-Dinitro(3,4-b)-(3,4-e)Difurazanopiperazine

DTIC Science & Technology

1989-07-01

nitrolysis or hydrolysis followed by nitration would yield 1. Unfortunately, all oxidation attempts failed. Using pyridinium SCHEME 11 PCC//&_ / :\\ NitiRly!is...26c or 71 - 0 / 0*---. w. 1 Jones’ NX NII N Reagent "- Hydrolysis ’NO2+" 32 5 chlorochromate (Reference 23) or Jones’ reagent (Reference 24) yielded

Study of the voltammetric behaviour of the ethalfluralin and methalpropalin and its determination in environmental matrices at hanging mercury drop electrode.

PubMed

Thriveni, T; Kumar, J Rajesh; Lee, Jin Young; Sreedhar, N Y

2009-04-01

An electroanalytical method has been developed for the determination of the herbicides ethalfluralin[N-ethyl-N-(2-methyl-2-propenyl)-2,6-dinitro-4-(trifluoromethyl) bezenamine] and methalpropalin [N-(2-methyl-2-propenyl)-2, 6-dinitro-N-propyl-4 (trifluoromethyl) benzenamine] by differential pulse adsorptive stripping voltammetry (DP-AdSV) on a hanging mercury drop electrode (HMDE) with universal buffer as supporting electrolyte. The optimum adsorption conditions were found to be pH 6.0, an accumulation potential of -0.6 V (HMDE vs SCE), an accumulation time of 80 s. and scan rate 45 mVs(-1). Calibration curve is linear in the range 1.30 x 10(-9) to 1.32 x 10(-5) M of ethalfluralin and 1.13 x 10(-5) to 2.0 x 10(-8) M of methalpropalin with detection limits of 1.08 x 10(-9) and 1.87 x 10(-8) M, respectively. The relative SD and correlation coefficients were found to be 1.24%, 0.998 and 1.34%, 0.995, respectively for ten replicates. The method is applied to the determination of the ethalfluralin and methalpropalin in formulations and environmental matrices.

40 CFR 414.91 - Toxic pollutant effluent limitations and standards for direct discharge point sources that use...

Code of Federal Regulations, 2012 CFR

2012-07-01

...(k)fluoranthene 59 22 Benzo(a)pyrene 61 23 Bis(2-ethylhexyl) phthalate 279 103 Carbon Tetrachloride... Di-n-butyl phthalate 57 27 1,2-Dichlorobenzene 163 77 1,3-Dichlorobenzene 44 31 1,4-Dichlorobenzene... phthalate 203 81 2,4-Dimethylphenol 36 18 Dimethyl phthalate 47 19 4,6-Dinitro-o-cresol 277 78 2,4...

40 CFR 414.91 - Toxic pollutant effluent limitations and standards for direct discharge point sources that use...

Code of Federal Regulations, 2014 CFR

2014-07-01

...(k)fluoranthene 59 22 Benzo(a)pyrene 61 23 Bis(2-ethylhexyl) phthalate 279 103 Carbon Tetrachloride... Di-n-butyl phthalate 57 27 1,2-Dichlorobenzene 163 77 1,3-Dichlorobenzene 44 31 1,4-Dichlorobenzene... phthalate 203 81 2,4-Dimethylphenol 36 18 Dimethyl phthalate 47 19 4,6-Dinitro-o-cresol 277 78 2,4...

Fusing porphyrins with polycyclic aromatic hydrocarbons and heterocycles for optoelectronic applications

DOEpatents

Thompson, Mark E.; Diev, Viacheslav; Hanson, Kenneth; Forrest, Stephen R.

2015-08-18

A compound that can be used as a donor material in organic photovoltaic devices comprising a non-activated porphyrin fused with one or more non-activated polycyclic aromatic rings or one or more non-activated heterocyclic rings can be obtained by a thermal fusion process. The compounds can include structures of Formula I: ##STR00001## By heating the reaction mixture of non-activated porphyrins with non-activated polycyclic aromatic rings or heterocyclic rings to a fusion temperature and holding for a predetermined time, fusion of one or more polycyclic rings or heterocyclic rings to the non-activated porphyrin core in meso,.beta. fashion is achieved resulting in hybrid structures containing a distorted porphyrin ring with annulated aromatic rings. The porphyrin core can be olygoporphyrins.

Second generation engineering of transketolase for polar aromatic aldehyde substrates.

PubMed

Payongsri, Panwajee; Steadman, David; Hailes, Helen C; Dalby, Paul A

2015-04-01

Transketolase has significant industrial potential for the asymmetric synthesis of carboncarbon bonds with new chiral centres. Variants evolved on propanal were found previously with nascent activity on polar aromatic aldehydes 3-formylbenzoic acid (3-FBA), 4-formylbenzoic acid (4-FBA), and 3-hydroxybenzaldehyde (3-HBA), suggesting a potential novel route to analogues of chloramphenicol. Here we evolved improved transketolase activities towards aromatic aldehydes, by saturation mutagenesis of two active-site residues (R358 and S385), predicted to interact with the aromatic substituents. S385 variants selectively controlled the aromatic substrate preference, with up to 13-fold enhanced activities, and KM values comparable to those of natural substrates with wild-type transketolase. S385E even completely removed the substrate inhibition for 3-FBA, observed in all previous variants. The mechanisms of catalytic improvement were both mutation type and substrate dependent. S385E improved 3-FBA activity via kcat, but reduced 4-FBA activity via KM. Conversely, S385Y/T improved 3-FBA activity via KM and 4-FBA activity via kcat. This suggested that both substrate proximity and active-site orientation are very sensitive to mutation. Comparison of all variant activities on each substrate indicated different binding modes for the three aromatic substrates, supported by computational docking. This highlights a potential divergence in the evolution of different substrate specificities, with implications for enzyme engineering. Copyright © 2015 Elsevier Inc. All rights reserved.

Aerobic Heterotrophic Bacterial Populations of Sewage and Activated Sludge

PubMed Central

Prakasam, T. B. S.; Dondero, N. C.

1970-01-01

An activated sludge from a sewage treatment plant and a laboratory activated sludge developed on an artificial waste were compared for their ability to utilize 11 aromatic compounds. There were several significant differences between them. The laboratory sludge contained higher numbers of organisms and metabolized the aromatics to a greater extent. Laboratory activated sludges acclimated to utilization of the aromatics differed from each other in population structure and the pattern of oxygen consumption with aromatic substrates. The oxidative patterns of uncontrolled mixed populations were unreliable for investigating metabolic pathways. Extracts of the various sludges elevated the plate counts of the sludges. PMID:5418946

Nitranilic acid hexahydrate, a novel benchmark system of the Zundel cation in an intrinsically asymmetric environment: spectroscopic features and hydrogen bond dynamics characterised by experimental and theoretical methods.

PubMed

Molčanov, Krešimir; Stare, Jernej; Vener, Mikhail V; Kojić-Prodić, Biserka; Mali, Gregor; Grdadolnik, Jože; Mohaček-Grošev, Vlasta

2014-01-21

Nitranilic acid (2,5-dihydroxy-3,6-dinitro-2,5-cyclohexadiene-1,4-dione) as a strong dibasic acid in acidic aqueous media creates the Zundel cation, H5O2(+). The structural unit in a crystal comprises (H5O2)2(+) (2,5-dihydroxy-3,6-dinitro-1,4-benzoquinonate)(2-) dihydrate where the Zundel cation reveals no symmetry, being an ideal case for studying proton dynamics and its stability. The Zundel cation and proton transfer dynamics are studied by variable-temperature X-ray diffraction, IR and solid-state NMR spectroscopy, and various quantum chemical methods, including periodic DFT calculations, ab initio molecular dynamics simulation, and quantization of nuclear motion along three fully coupled internal coordinates. The Zundel cation features a short H-bond with the O···O distance of 2.433(2) Å with an asymmetric placement of hydrogen. The proton potential is of a single well type and, due to the non-symmetric surroundings, of asymmetric shape. The formation of the Zundel cation is facilitated by the electronegative NO2 groups. The employed spectroscopic techniques supported by calculations confirm the presence of a short H-bond with a complex proton dynamics.

Multiple Functions of Aromatic-Carbohydrate Interactions in a Processive Cellulase Examined with Molecular Simulation*

PubMed Central

Payne, Christina M.; Bomble, Yannick J.; Taylor, Courtney B.; McCabe, Clare; Himmel, Michael E.; Crowley, Michael F.; Beckham, Gregg T.

2011-01-01

Proteins employ aromatic residues for carbohydrate binding in a wide range of biological functions. Glycoside hydrolases, which are ubiquitous in nature, typically exhibit tunnels, clefts, or pockets lined with aromatic residues for processing carbohydrates. Mutation of these aromatic residues often results in significant activity differences on insoluble and soluble substrates. However, the thermodynamic basis and molecular level role of these aromatic residues remain unknown. Here, we calculate the relative ligand binding free energy by mutating tryptophans in the Trichoderma reesei family 6 cellulase (Cel6A) to alanine. Removal of aromatic residues near the catalytic site has little impact on the ligand binding free energy, suggesting that aromatic residues immediately upstream of the active site are not directly involved in binding, but play a role in the glucopyranose ring distortion necessary for catalysis. Removal of aromatic residues at the entrance and exit of the Cel6A tunnel, however, dramatically impacts the binding affinity, suggesting that these residues play a role in chain acquisition and product stabilization, respectively. The roles suggested from differences in binding affinity are confirmed by molecular dynamics and normal mode analysis. Surprisingly, our results illustrate that aromatic-carbohydrate interactions vary dramatically depending on the position in the enzyme tunnel. As aromatic-carbohydrate interactions are present in all carbohydrate-active enzymes, these results have implications for understanding protein structure-function relationships in carbohydrate metabolism and recognition, carbon turnover in nature, and protein engineering strategies for biomass utilization. Generally, these results suggest that nature employs aromatic-carbohydrate interactions with a wide range of binding affinities for diverse functions. PMID:21965672

Antioxidant effect of aromatic volatiles emitted by Lavandula dentata, Mentha spicata, and M. piperita on mouse subjected to low oxygen condition.

PubMed

Hu, Zenghui; Wang, Chunling; Shen, Hong; Zhang, Kezhong; Leng, Pingsheng

2017-12-01

This study aims to investigate the antioxidant effect of aromatic volatiles of three common aromatic plants, Lavandula dentata, Mentha spicata, and M. piperita. In this study, kunming mice subjected to low oxygen condition were treated with the volatiles emitted from these aromatic plants through inhalation administration. Then the blood cell counts, and the activities and gene expressions of antioxidant enzymes in different tissues were tested. The results showed that low oxygen increased the counts of red blood cells, white blood cells, and blood platelets of mice, and aromatic volatiles decreased their counts. Exposure to aromatic volatiles resulted in decreases in the malonaldehyde contents, and increases in the activities and gene expressions of superoxide dismutase, glutathione peroxidase, and catalase in different tissues under low oxygen. In addition, as the main component of aromatic volatiles, eucalyptol was the potential source that imparted positive antioxidant effect.

Effect of Oryzalin and 1,1-Dimethylpiperidinium Chloride on Cotton and Tomato Roots Infected with the Root-knot Nematode, Meloidogyne incognita

PubMed Central

Orum, T. V.; Bartels, P. G.; McClure, M. A.

1979-01-01

Oryzalin (3,5-dinitro-N4,N4-dipropyl-sulfanilamide) and BAS 083 (l,l-dimethylpiperdinium chloride) reduced root-knot infection in tomato roots when respectively applied as a soil drench at 20 ppm and 10,000 ppm. Oryzalin reduced knot counts with various intervals between treatment and inoculation. BAS 083 reduced knot counts only when applied before inoculation. Oryzalin was shown not to be a contact nematicide, and BAS 083 was only a weak one. Neither compound reduced penetration by infective larvae. Postinfection reduction in knot counts by Oryzalin and BAS 083 resulted, in part, from activation of natural defense mechanisms of the host. Giant-cell development in cotton roots inoculated with nematodes was inhibited by Oryzalin. Lateral root development was inhibited by BAS 083. PMID:19305533

New Trends in Research of Energetic Materials (5th Seminar) Held in Pardubice, Czech Republic on 24-25 Apr 2002

DTIC Science & Technology

2002-04-01

stearic acid, palmitic acid, octadecanol, zinc stearate, silicone grease, silicone oil, organosilicon resin , asphalt, and estane, as single or...small amount of urea was present. The product crystallized directly from the reaction mixture. The following reaction conditions were changed in the...triazacycloheptane (3) includes Mannich condensation of ethylenedinitramine with formaldehyde and monoethanolamine to give 3- ethanol- 1,5-dinitro-l1,3,5

Polymer of phosphonylmethyl-2,4- and -2,6-diamino benzene and polyfunctional monomer

NASA Technical Reports Server (NTRS)

Mikroyannidis, J. A. (Inventor); Kourtides, D. A. (Inventor)

1986-01-01

A phosphonyl methyl benzene is prepared by nitration to produce a 2,4-dinitro phosphonyl methyl benzene, which is then reduced to a diamino compound. The diamino compound is then used to cure a polymerizable monomer. The diamino compound may be polymerized with polyfunctional epoxides to produce heat and fire resistant polymer structures for making flame and fire resistant polymer structures such as for aircraft secondary structures.

Medicinally important aromatic plants with radioprotective activity

PubMed Central

Samarth, Ravindra M; Samarth, Meenakshi; Matsumoto, Yoshihisa

2017-01-01

Aromatic plants are often used as natural medicines because of their remedial and inherent pharmacological properties. Looking into natural resources, particularly products of plant origin, has become an exciting area of research in drug discovery and development. Aromatic plants are mainly exploited for essential oil extraction for applications in industries, for example, in cosmetics, flavoring and fragrance, spices, pesticides, repellents and herbal beverages. Although several medicinal plants have been studied to treat various conventional ailments only a handful studies are available on aromatic plants, especially for radioprotection. Many plant extracts have been reported to contain antioxidants that scavenge free radicals produced due to radiation exposure, thus imparting radioprotective efficacy. The present review focuses on a subset of medicinally important aromatic plants with radioprotective activity. PMID:29134131

Flexibility of active-site gorge aromatic residues and non-gorge aromatic residues in acetylcholinesterase

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ghattyvenkatakrishna, Pavan K; Uberbacher, Edward C

2013-01-01

The presence of an unusually large number of aromatic residues in the active site gorge of acetylcholinesterase has been a topic of great interest. Flexibility of these residues has been suspected to be a key player in controlling ligand traversal in the gorge. This raises the question of whether the over representation of aromatic residues in the gorge implies higher than normal flexibility of those residues. The current study suggests that it does not. Large changes in the hydrophobic cross sectional area due to dihedral oscillations are probably the reason behind their presence in the gorge.

Design of aromatic-containing cell-penetrating peptide mimics with structurally modified π electronics.

PubMed

deRonde, Brittany M; Birke, Alexander; Tew, Gregory N

2015-02-09

Cell-penetrating peptides (CPPs) and their synthetic mimics (CPPMs) represent a class of molecules that facilitate the intracellular delivery of various cargo. Previous studies indicated that the presence of aromatic functionalities improved CPPM activity. Given that aromatic functionalities play prominent roles in membrane biology and participate in various π interactions, we explored whether these interactions could be optimized for improved CPPM activity. CPPMs were synthesized by ring-opening metathesis polymerization by using monomers that contained aromatic rings substituted with electron-donating and electron-withdrawing groups and covered an electrostatic potential range from -29.69 to +15.57 kcal mol(-1) . These groups altered the quadrupole moments of the aromatic systems and were used to test if such structural modifications changed CPPM activity. CPPMs were added to dye-loaded vesicles and the release of carboxyfluorescein was monitored as a function of polymer concentration. Changes in the effective polymer concentration to release 50% of the dye (effective concentration, EC50 ) were monitored. Results from this assay showed that the strength of the electron-donating and electron-withdrawing groups incorporated in the CPPMs did not alter polymer EC50 values or activity. This suggests that other design parameters may have a stronger impact on CPPM activity. In addition, these results indicate that a wide range of aromatic groups can be incorporated without negatively impacting polymer activity. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Preparation and Purification of Multigram Quantities of TAX and SEX.

DTIC Science & Technology

1981-12-01

Synthesis Purification Nitrolysis 2L AS[TNIACT (Cletiloe -m powowe0m N noeaemy and Identify by block number) This final report describes the multigram... synthesis and purification of 3 kg of 1-acetylhexahydro-3,5-dinitro-1,3,5-triazine (TAX) and the feasibility of producing kilogram quantities of l...residual impurities; (3) demonstrate the feasibility of the synthesis approach on a one-pound batch reaction; and (4) provide a cost-plus-fixed-fee estimate

Distribution and Fate of Energetics on DoD Test and Training Ranges: Interim Report 6

DTIC Science & Technology

2006-11-01

0.75 1,2,3,7,8-pentachlorodibenzofuran pg/g 2 6 0.34 0.73 0.54 1,2,4-trichlorobenzene μg/kg 1 353 2 2 2 1,2-dibromo-3- chloropropane μg/kg 0 5 ND ND...nitration products of TNT synthesis Hexahydro- 1 -nitroso-3,5-dinitro- 1,3,5-triazine MNX Mono nitroso derivative of RDX produced by microbial degradation...xvii 1 Introduction

Preliminary Assessment of Relative Toxicity and Mutagenic Potential of 1 Nitroso-3,5-Dinitro-1,3,5-Triazacyclohexane (Mononitroso-RDX)

DTIC Science & Technology

1984-09-01

Inhalation Toxicology, Mehlman, Crammer , and Shapiro, editors, 302-344, Pathotox Publishers, Inc., Park Forest South, Illinois (1977). 8. Shimkin, M. and G...Laboratory Studies. (3) Final Rule , Pesticide Programs; Good Laboratory Practice Standards; 48 Federal Register (FR) 53963-53969, 29 November 1983. (4...Final Rule , Toxic Substances Control; Good Laboratory Practice Standards; 48 Federal Register (FR) 53922-53944, 29 November 1983. b. Facilities were

Crystal structure of 4,5-dinitro-1 H-imidazole

DOE PAGES

Windler, G. Kenneth; Scott, Brian L.; Tomson, Neil C.; ...

2015-01-01

Here, the title compound, C 3H 2N 4O 4, forms crystals with two molecules in the asymmetric unit which are conformationally similar. With the exception of the O atoms of the nitro groups, the molecules are essentially planar. In the crystal, adjacent molecules are associated by N—H...N hydrogen bonds involving the imidazole N—H donors and N-atom acceptors of the unsaturated nitrogen of neighboring rings, forming layers parallel to (010).

SEDIMENT-ASSOCIATED REACTIONS OF AROMATIC AMINES: QSAR DEVELOPMENT

EPA Science Inventory

Despite the common occurrence of the aromatic amine functional group in environmental contaminants, few quantitative structure-activity relationships (QSARs) have been developed to predict sorption kinetics for aromatic amines in natural soils and sediments. Towards the goal of d...

Characterization of an aryl-alcohol oxidase from the plant saprophytic basidiomycete Coprinopsis cinerea with broad substrate specificity against aromatic alcohols.

PubMed

Tamaru, Yoshiaki; Umezawa, Kiwamu; Yoshida, Makoto

2018-07-01

The aim of the study was to obtain information about the enzymatic properties of aryl-alcohol oxidase from the plant saprophytic basidiomycete Coprinopsis cinerea (rCcAAO), which is classified into the auxiliary activities family 3 subfamily 2 (AA3_2). The gene encoding AAO from the plant saprophytic basidiomycete Coprinopsis cinerea (CcAAO) was cloned, and the recombinant CcAAO (rCcAAO) was heterologously expressed in the methylotrophic yeast Pichia pastoris. The purified rCcAAO showed significant activity not only against trans,trans-2,4-hexadien-1-ol but also against a broad range of aromatic alcohols including aromatic compounds that were reported to be poor substrates for known AAOs. Moreover, site-directed mutagenesis analysis demonstrated that mutants with substitutions from leucine to phenylalanine and tryptophan at position 416 exhibited decreases of activity for aromatic alcohols but still maintained the activity for trans,trans-2,4-hexadien-1-ol. Leucine 416 in CcAAO contributes to the broad substrate specificity against various aromatic alcohols, which is useful for the production of hydrogen peroxide using this enzyme.

Synthesis of thermally stable polypyrazoles, polypyrimidines and other heteroaromatic polymers

NASA Technical Reports Server (NTRS)

Bass, R. G.

1986-01-01

As part of a continuing effort to prepare high performance-high temperature polymers for functional and structural applications, the reactions of aromatic dipropynones with aromatic dihydrazine, aromatic dithiols, and aromatic diamidines to provide polypyrazoles, polyenonesulfides, and polypyrimidines respectively were investigated. During the past year, it was demonstrated that polypyrazoles and polyenonesulfides may be prepared by the proposed procedures. However, the preparation of polypyrimidines was not achieved. The preparation and characterization of some polypyrazolones by reaction or aromatic dihydrazines with an activated diacetylenic diester was achieved.

Sensitive, Selective Test For Hydrazines

NASA Technical Reports Server (NTRS)

Roundbehler, David; Macdonald, Stephen

1993-01-01

Derivatives of hydrazines formed, then subjected to gas chromatography and detected via chemiluminescence. In method of detecting and quantifying hydrazine vapors, vapors reacted with dinitro compound to enhance sensitivity and selectivity. Hydrazine (HZ), monomethyl hydrazine, (MMH), and unsymmetrical dimethylhydrazine (UDMH) analyzed quantitatively and qualitatively, either alone or in mixtures. Vapors collected and reacted with 2,4-dinitrobenzaldehyde, (DNB), making it possible to concentrate hydrazine in derivative form, thereby increasing sensitivity to low initial concentrations. Increases selectivity because only those constituents of sample reacting with DNB concentrated for analysis.

Biodegradation of Trinitrotoluene (Alpha TNT) and Its Production Isomers

DTIC Science & Technology

1975-07-01

medium, suqgesting that some of the nitro groups may be released as nitrite. DO .ETn 1473 EDITION OF t NOV 6» IS OBSOLETE iMW- vr IJNWASS...nitrite in the medium and the formation of catechol, Tewfik and Evans (2) demonstrated the biodegradation of 3,5-dinitro-o- cresol via reduction of the 5... nitro group to an amino group which is then replaced by a hydroxyl group. After this the same series of reactions occur with the 3- nitro group

Himalayan Aromatic Medicinal Plants: A Review of their Ethnopharmacology, Volatile Phytochemistry, and Biological Activities

PubMed Central

Joshi, Rakesh K.; Satyal, Prabodh; Setzer, Wiliam N.

2016-01-01

Aromatic plants have played key roles in the lives of tribal peoples living in the Himalaya by providing products for both food and medicine. This review presents a summary of aromatic medicinal plants from the Indian Himalaya, Nepal, and Bhutan, focusing on plant species for which volatile compositions have been described. The review summarizes 116 aromatic plant species distributed over 26 families. PMID:28930116

Increasing Prion Propensity by Hydrophobic Insertion

PubMed Central

Petri, Michelina; Flores, Noe; Rogge, Ryan A.; Cascarina, Sean M.; Ross, Eric D.

2014-01-01

Prion formation involves the conversion of proteins from a soluble form into an infectious amyloid form. Most yeast prion proteins contain glutamine/asparagine-rich regions that are responsible for prion aggregation. Prion formation by these domains is driven primarily by amino acid composition, not primary sequence, yet there is a surprising disconnect between the amino acids thought to have the highest aggregation propensity and those that are actually found in yeast prion domains. Specifically, a recent mutagenic screen suggested that both aromatic and non-aromatic hydrophobic residues strongly promote prion formation. However, while aromatic residues are common in yeast prion domains, non-aromatic hydrophobic residues are strongly under-represented. Here, we directly test the effects of hydrophobic and aromatic residues on prion formation. Remarkably, we found that insertion of as few as two hydrophobic residues resulted in a multiple orders-of-magnitude increase in prion formation, and significant acceleration of in vitro amyloid formation. Thus, insertion or deletion of hydrophobic residues provides a simple tool to control the prion activity of a protein. These data, combined with bioinformatics analysis, suggest a limit on the number of strongly prion-promoting residues tolerated in glutamine/asparagine-rich domains. This limit may explain the under-representation of non-aromatic hydrophobic residues in yeast prion domains. Prion activity requires not only that a protein be able to form prion fibers, but also that these fibers be cleaved to generate new independently-segregating aggregates to offset dilution by cell division. Recent studies suggest that aromatic residues, but not non-aromatic hydrophobic residues, support the fiber cleavage step. Therefore, we propose that while both aromatic and non-aromatic hydrophobic residues promote prion formation, aromatic residues are favored in yeast prion domains because they serve a dual function, promoting both prion formation and chaperone-dependent prion propagation. PMID:24586661

Significance of Xenobiotic Metabolism for Bioaccumulation Kinetics of Organic Chemicals in Gammarus pulex

PubMed Central

2012-01-01

Bioaccumulation and biotransformation are key toxicokinetic processes that modify toxicity of chemicals and sensitivity of organisms. Bioaccumulation kinetics vary greatly among organisms and chemicals; thus, we investigated the influence of biotransformation kinetics on bioaccumulation in a model aquatic invertebrate using fifteen 14C-labeled organic xenobiotics from diverse chemical classes and physicochemical properties (1,2,3-trichlorobenzene, imidacloprid, 4,6-dinitro-o-cresol, ethylacrylate, malathion, chlorpyrifos, aldicarb, carbofuran, carbaryl, 2,4-dichlorophenol, 2,4,5-trichlorophenol, pentachlorophenol, 4-nitrobenzyl-chloride, 2,4-dichloroaniline, and sea-nine (4,5-dichloro-2-octyl-3-isothiazolone)). We detected and identified metabolites using HPLC with UV and radio-detection as well as high resolution mass spectrometry (LTQ-Orbitrap). Kinetics of uptake, biotransformation, and elimination of parent compounds and metabolites were modeled with a first-order one-compartment model. Bioaccumulation factors were calculated for parent compounds and metabolite enrichment factors for metabolites. Out of 19 detected metabolites, we identified seven by standards or accurate mass measurements and two via pathway analysis and analogies to other compounds. 1,2,3-Trichlorobenzene, imidacloprid, and 4,6-dinitro-o-cresol were not biotransformed. Dietary uptake contributed little to overall uptake. Differentiation between parent and metabolites increased accuracy of bioaccumulation parameters compared to total 14C measurements. Biotransformation dominated toxicokinetics and strongly affected internal concentrations of parent compounds and metabolites. Many metabolites reached higher internal concentrations than their parents, characterized by large metabolite enrichment factors. PMID:22321051

Biologically important compounds in synfuels processes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Clark, B R; Ho, C; Griest, W H

1980-01-01

Crude products, by-products and wastes from synfuel processes contain a broad spectrum of chemical compounds - many of which are active in biological systems. Discerning which compound classes are most important is necessary in order to establish effective control over release or exposure. Polycyclic aromatic hydrocarbons (PAH), multialkylated PAH, primary aromatic amines and N-heterocyclic PAH are significant contributors to the overall mutagenic activities of a large number of materials examined. Ames test data show that the basic, primary aromatic amine fraction is the most active. PAHs, multialkylated PAHs and N-heterocyclic PAHs are all components of the neutral fraction. In nearlymore » all cases, the neutral fractions contribute the largest portion of the mutagenic activity, while the basic primary aromatic amine fractions have the highest specific activity. Neutral fractions are usually the largest (wt %) whereas the total basic fractions are small by comparison; thus, the overall greater contribution of the neutral fraction to the mutagenic activity of most samples. Biologically active constituents are isolated in preparative scale amounts from complex mixtures utilizing combinations of liquid-liquid extraction and various liquid chromatographic column-eluant combinations. Fractions are characterized using a combination of spectroscopic techniques and gas chromatography/mass spectrometry.« less

Alkaline hydrolysis of the cyclic nitramine explosives RDX, HMX, and CL-20: new insights into degradation pathways obtained by the observation of novel intermediates.

PubMed

Balakrishnan, Vimal K; Halasz, Annamaria; Hawari, Jalal

2003-05-01

Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX, I) and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) hydrolyze at pH > 10 to form end products including NO2-, HCHO, HCOOH, NH3, and N2O, but little information is available on intermediates, apart from the tentatively identified pentahydro-3,5-dinitro-1,3,5-triazacyclohex-1-ene (II). Despite suggestions that RDX and HMX contaminated groundwater could be economically treated via alkaline hydrolysis, the optimization of such a process requires more detailed knowledge of intermediates and degradation pathways. In this study, we hydrolyzed the monocyclic nitramines RDX, MNX (hexahydro-1-nitroso-3,5-dinitro-1,3,5-triazine), and HMX in aqueous solution (pH 10-12.3) and found that nitramine removal was accompanied by formation of 1 molar equiv of nitrite and the accumulation of the key ring cleavage product 4-nitro-2,4-diazabutanal (4-NDAB, O2NNHCH2NHCHO). Most of the remaining C and N content of RDX, MNX, and HMX was found in HCHO, N2O, HCOOH, and NH3. Consequently, we selected RDX as a model compound and hydrolyzed it in aqueous acetonitrile solutions (pH 12.3) in the presence and absence of hydroxypropyl-beta-cyclodextrin (HP-beta-CD) to explore other early intermediates in more detail. We observed a transient LC-MS peak with a [M-H] at 192 Da that was tentatively identified as 4,6-dinitro-2,4,6-triaza-hexanal (O2NNHCH2NNO2CH2NHCHO, III) considered as the hydrolyzed product of II. In addition, we detected another novel intermediate with a [M-H] at 148 Da that was tentatively identified as a hydrolyzed product of III, namely, 5-hydroxy-4-nitro-2,4-diaza-pentanal (HOCH2NNO2CH2NHCHO, IV). Both III and IV can act as precursors to 4-NDAB. In the case of the polycyclic nitramine 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20), denitration (two NO2-) also led to the formation of HCOOH, NH3, and N2O, but neither HCHO nor 4-NDAB were detected. The results provide strong evidence that initial denitration of cyclic nitramines in water is sufficient to cause ring cleavage followed by spontaneous decomposition to form the final products.

Modulation of ethoxyresorufin O-deethylase and glutathione S-transferase activities in Nile tilapia (Oreochromis niloticus) by polycyclic aromatic hydrocarbons containing two to four rings: implications in biomonitoring aquatic pollution.

PubMed

Pathiratne, Asoka; Hemachandra, Chamini K

2010-08-01

Despite ubiquity of polycyclic aromatic hydrocarbons (PAHs) in the tropical environments, little information is available concerning responses of tropical fish to PAHs and associated toxicity. In the present study, effects of five PAHs containing two to four aromatic rings on hepatic CYP1A dependent ethoxyresorufin O-deethylase (EROD), glutathione S-transferase (GST) and serum sorbitol dehydrogenase (SDH) activities in Nile tilapia, a potential fish species for biomonitoring pollution in tropical waters, were evaluated. Results showed that EROD activities were induced by the PAHs containing four aromatic rings (pyrene and chrysene) in a dose dependent manner. However PAHs with two to three aromatic rings (naphthalene, phenanthrene and fluoranthene) caused no effect or inhibition of EROD activities depending on the dose and the duration. Fluoranthene was the most potent inhibitor. SDH results demonstrated that high doses of fluoranthene induced hepatic damage. GST activity was induced by the lowest dose of phenanthrene, fluoranthene and chrysene but high doses had no effect. The results indicate that induction of EROD enzyme in Nile tilapia is a useful biomarker of exposure to PAHs such as pyrene and chrysene. However EROD inhibiting PAHs such as fluoranthene in the natural environment may modulate the EROD inducing potential of other PAHs thereby influencing PAH exposure assessments.

PABA/NO lead optimization: Improved targeting of cytotoxicity to glutathione S-transferase P1-overexpressing cancer cells.

PubMed

Kim, Youseung; Maciag, Anna E; Cao, Zhao; Deschamps, Jeffrey R; Saavedra, Joseph E; Keefer, Larry K; Holland, Ryan J

2015-08-01

PABA/NO [O(2)-{2,4-dinitro-5-[4-(N-methylamino)benzoyloxy]phenyl} 1-(N,N-dimethylamino) diazen-1-ium-1,2-diolate] is a nitric oxide (NO)-releasing arylating agent designed to be selectively activated by reaction with glutathione (GSH) on catalysis by glutathione S-transferase P1 (GSTP1), an enzyme frequently overexpressed in cancer cells. PABA/NO has proven active in several cancer models in vitro and in vivo, but its tendency to be metabolized via a variety of pathways, some that generate inactive metabolites and hydrolysis products, limits its potential as a drug. Here we show that a simple replacement of cyano for nitro at the 4 position to give compound 4b ('p-cyano-PABA/NO') has the dual effect of slowing the undesired side reactions while enhancing the proportion of NO release and arylating activity on catalysis by GSTP1. Compound 4b showed increased resistance to hydrolysis and uncatalyzed reaction with GSH, along with a more favorable product distribution in the presence of GSTP1. It also showed significant proapoptotic activity. The data suggest p-cyano-PABA/NO to be a more promising prodrug than PABA/NO, with better selectivity toward cancer cells. Published by Elsevier Ltd.

Influence of polychlorinated aromatic compounds on the biotransformation and toxicity of organophosphorus pesticides (OP) to the Daphnia magna

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tonkopii, V.; Zagrebin, A.; Sherstneva, L.

1995-12-31

The effect of different polychlorinated aromatics (DDT, Aroclor 1254, certain polychlorinated biphenyls and dibenzofurans) on the toxicity of OP (DDVP paraoxon, malaoxon) to Daphnia magna was studied. Pretreatment of daphnids with chlorinated compounds during 72 hours in nontoxic concentrations (1/5--1/20 CL{sub 50}) has been shown to reduce the toxicity of OP for hydrobionts. For study of influence of chlorinated compounds on biotransformation of OP the activity of enzymes which are hydrolyzing the OP was investigated in Daphnia`s homogenates or microsomes. The activity of carboxylesterase (tributyrinase, aliesterase) and arylesterase (phosphorylphosphatase) with usage as substrates accordingly {alpha}-naphthylacetate and paraoxon was measured. Besidesmore » that the activity of cholinesterase with application of propionylthiocholine as substrate was determined. After polychlorinated aromatic compounds treatment of daphnids activities of both aryl-and carboxylesterase increased markedly. It decreased the inhibition of Daphnia`s cholinesterase caused by incubation with OP in concentrations 0.5--1.0 CL{sub 50}. Thus the induction by chlorinate aromatics of OP metabolizing enzymes seems to play the important role in reduction of OP toxicity to Daphnia magna. Perhaps the aryl- and carboxylesterase of Daphnia can be used as biomarkers of pollution by polychlorinated aromatics in water.« less

Remarkably selective iridium catalysts for the elaboration of aromatic C-H bonds.

PubMed

Cho, Jian-Yang; Tse, Man Kin; Holmes, Daniel; Maleczka, Robert E; Smith, Milton R

2002-01-11

Arylboron compounds have intriguing properties and are important building blocks for chemical synthesis. A family of Ir catalysts now enables the direct synthesis of arylboron compounds from aromatic hydrocarbons and boranes under "solventless" conditions. The Ir catalysts are highly selective for C-H activation and do not interfere with subsequent in situ transformations, including Pd-mediated cross-couplings with aryl halides. By virtue of their favorable activities and exceptional selectivities, these Ir catalysts impart the synthetic versatility of arylboron reagents to C-H bonds in aromatic and heteroaromatic hydrocarbons.

Bacterial Degradation of Aromatic Compounds

PubMed Central

Seo, Jong-Su; Keum, Young-Soo; Li, Qing X.

2009-01-01

Aromatic compounds are among the most prevalent and persistent pollutants in the environment. Petroleum-contaminated soil and sediment commonly contain a mixture of polycyclic aromatic hydrocarbons (PAHs) and heterocyclic aromatics. Aromatics derived from industrial activities often have functional groups such as alkyls, halogens and nitro groups. Biodegradation is a major mechanism of removal of organic pollutants from a contaminated site. This review focuses on bacterial degradation pathways of selected aromatic compounds. Catabolic pathways of naphthalene, fluorene, phenanthrene, fluoranthene, pyrene, and benzo[a]pyrene are described in detail. Bacterial catabolism of the heterocycles dibenzofuran, carbazole, dibenzothiophene, and dibenzodioxin is discussed. Bacterial catabolism of alkylated PAHs is summarized, followed by a brief discussion of proteomics and metabolomics as powerful tools for elucidation of biodegradation mechanisms. PMID:19440284

Four Aromatic Sulfates with an Inhibitory Effect against HCV NS3 Helicase from the Crinoid Alloeocomatella polycladia

PubMed Central

Hermawan, Idam; Furuta, Atsushi; Higashi, Masahiro; Fujita, Yoshihisa; Akimitsu, Nobuyoshi; Yamashita, Atsuya; Moriishi, Kohji; Tsuneda, Satoshi; Tani, Hidenori; Nakakoshi, Masamichi; Tsubuki, Masayoshi; Sekiguchi, Yuji; Noda, Naohiro; Tanaka, Junichi

2017-01-01

Bioassay-guided separation of a lipophilic extract of the crinoid Alloeocomatella polycladia, inhibiting the activity of HCV NS3 helicase, yielded two groups of molecules: cholesterol sulfate and four new aromatic sulfates 1–4. The structures of the aromatics were elucidated by spectroscopic analysis in addition to theoretical studies. The aromatic sulfates 1–4 showed moderate inhibition against NS3 helicase with IC50 values of 71, 95, 7, and 5 μM, respectively. PMID:28398249

Four Aromatic Sulfates with an Inhibitory Effect against HCV NS3 Helicase from the Crinoid Alloeocomatella polycladia.

PubMed

Hermawan, Idam; Furuta, Atsushi; Higashi, Masahiro; Fujita, Yoshihisa; Akimitsu, Nobuyoshi; Yamashita, Atsuya; Moriishi, Kohji; Tsuneda, Satoshi; Tani, Hidenori; Nakakoshi, Masamichi; Tsubuki, Masayoshi; Sekiguchi, Yuji; Noda, Naohiro; Tanaka, Junichi

2017-04-11

Bioassay-guided separation of a lipophilic extract of the crinoid Alloeocomatella polycladia , inhibiting the activity of HCV NS3 helicase, yielded two groups of molecules: cholesterol sulfate and four new aromatic sulfates 1 - 4 . The structures of the aromatics were elucidated by spectroscopic analysis in addition to theoretical studies. The aromatic sulfates 1 - 4 showed moderate inhibition against NS3 helicase with IC 50 values of 71, 95, 7, and 5 μM, respectively.

EXAFS study of some coordination polymers of copper

NASA Astrophysics Data System (ADS)

Deshpande, A. P.

1995-02-01

The EXAFS spectra for (1) azelaic acid bis phenyl hydrazide, (2) azelaic acid bis 2,4 dinitro phenyl hydrazide and (3) sebacic acid bis phenyl hydrazide coordination polymers of copper were obtained using the EXAFS facility of the Daresbury Laboratory. The EXAFS analysis revealed that copper is surrounded by four nitrogen and two oxygen atoms in the first coordination shell, while the second coordination shell consists of two carbon atoms. This information suggests the octahedral geometry for the repeating units of polymeric complexes, in contrast to the square planar geometry previously proposed.

Aromatization of n-hexane over ZnO/H-ZSM-5 catalysts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kanai, J.; Kawata, N.

The mechanism of transformation of n-hexane into aromatics over ZnO/H-ZSM-5 catalyst has been investigated. The yields of aromatics in the transformation of n-hexane over H-ZSM-5 are enhanced by mechanical mixing of ZnO as well as by ion exchange or impregnation of zinc cation. It is concluded that aromatization of n-hexane over ZnO/H-ZSM-5 is a bifunctional reaction, and that ZnO as well as H-ZSM-5 takes part both in the activation of n-hexane and in the aromatization of lower olefins. By contrasting the conversion of n-hexane with that of 1-hexane, it is found that aromatization of n-hexane over ZnO/H-ZSM-5 involves both themore » dehydrogenation of n-hexane into hexene and that of the oligomerized products into aromatics. It is proposed that ZnO catalyzes the dehydrogenation of n-hexane into hexene and of the oligomerized products into aromatics.« less

Environmental assessment of aromatic hydrocarbons-contaminated sediments of the Mexican Salina Cuz Bay.

PubMed

González-Macías, C; Schifter, I; Lluch-Cota, D B; Méndez-Rodríguez, L; Hernández-Vázquez, S

2007-10-01

Concentrations of total aromatic hydrocarbons and extractable organic matter in the water column and sediment were determined in samples collected in the course of the last 20 years from the Salina Cruz Harbor, México, to assess the degree of organic contamination. In sediments, organic compounds accumulate in shallow areas mostly associated with extractable organic matter and fine fractions. Calculated geocumulation index and enrichment factors suggest that contamination could be derived from anthropogenic activities attributed to harbor and ship scrapping activities, as well as transboundary source. Concentration of total aromatic hydrocarbons (as chrysene equivalents) ranged from 0.01 to 534 microg l(-1) in water, and from 0.10 to 2,160 microg g(-1) in sediments. Total aromatic concentration of 5 microg g(-1) is proposed as background concentration.

Changes in mutagenicity of protein pyrolyzates by reaction with nitrite.

PubMed

Yoshida, D; Matsumoto, T

1978-09-01

Pyrolyzates of protein and related materials were treated with nitrite under acidic conditions, and the mutagenic activity toward Salmonella tester strains was determined. After treatment with nitrite in acidic solution, casein pyrolyzate, an extract of roasted chicken meat, tobacco-smoke condensate and some aromatic amines showed appreciable decreases in their mutagenic activities toward Salmonella typhimurium TA 98. Aromatic amines in the pyrolyzates may be changed by nitrite treatment to other forms having no or lower mutagenic activity toward Salmonella typhimurium TA 98. The contribution by aromatic amines to the total mutagenic activity of the pyrolyzates was as high as 80% in both casein pyrolyzate and extract of roasted chicken meat and 50% in tobacco-smoke condensate. Pyrolyzates of protein and related materials did not show a decrease in the mutagenic activity toward Salmonella typhimurium TA 100 with the same treatment.

Conformationally restrained aromatic analogues of fosmidomycin and FR900098.

PubMed

Kurz, Thomas; Schlüter, Katrin; Pein, Miriam; Behrendt, Christoph; Bergmann, Bärbel; Walter, Rolf D

2007-07-01

The synthesis and in-vitro antimalarial activity of conformationally restrained bis(pivaloyloxymethyl) ester analogues of the natural product fosmidomycin is presented. In contrast to alpha-aryl-substituted analogues, conformationally restrained aromatic analogues exhibit only moderate in-vitro antimalarial activity against the chloroquine-sensitive strain 3D7 of Plasmodium falciparum. The most active derivative displays an IC(50) value of 47 microM.

Cu-catalyzed C(sp³)-H bond activation reaction for direct preparation of cycloallyl esters from cycloalkanes and aromatic aldehydes.

PubMed

Zhao, Jincan; Fang, Hong; Han, Jianlin; Pan, Yi

2014-05-02

Cu-catalyzed dehydrogenation-olefination and esterification of C(sp(3))-H bonds of cycloalkanes with TBHP as an oxidant has been developed. The reaction involves four C-H bond activations and gives cycloallyl ester products directly from cycloalkanes and aromatic aldehydes.

DEPENDENCY OF POLYCHLORINATED BIPHENYL AND POLYCYCLIC AROMATIC HYDROCARBON BIOACCUMULATION IN MYA ARENARIA ON BOTH WATER COLUMN AND SEDIMENT BED CHEMICAL ACTIVITIES

EPA Science Inventory

The bioaccumulation of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) by the filter-feeding soft-shell clam Mya arenaria was evaluated at three sites near Boston (MA, USA) by assessing the chemical activities of those hydrophobic organic compounds (H...

Remediation of aged diesel contaminated soil by alkaline activated persulfate.

PubMed

Lominchar, M A; Santos, A; de Miguel, E; Romero, A

2018-05-01

The present work studies the efficiency of alkaline activated persulfate (PS) to remediate an aged diesel fuel contaminated soil from a train maintenance facility. The Total Petroleum Hydrocarbon (TPH) concentration in soil was approximately 5000mgkg -1 with a ratio of aliphatic:aromatic compounds of 70:30. Aromatic compounds were mainly naphtalenes and phenanthrenes. The experiments were performed in batch mode where different initial concentrations of persulfate (105mM, 210mM and 420mM) and activator:persulfate ratios (2 and 4) were evaluated, with NaOH used as activator. Runs were carried out during 56days. Complete TPH conversion was obtained with the highest concentration of PS and activator, whereas in the other runs the elimination of fuel ranged between 60 and 77%. Besides, the abatement of napthalenes and phenantrenes was faster than aliphatic reduction (i. e. after 4days of treatment, the conversions of the aromatic compounds were around 0.8 meanwhile the aliphatic abatements were 0.55) and no aromatic oxidation intermediates from naphtalenes or phenantrenes were detected. These results show that this technology is effective for the remediation of aged diesel in soil with alkaline pH. Copyright © 2017 Elsevier B.V. All rights reserved.

Anti-aging activities of extracts from Tunisian medicinal halophytes and their aromatic constituents

PubMed Central

Jdey, A.; Falleh, H.; Ben Jannet, S.; Mkadmini Hammi, K.; Dauvergne, X.; Magné, C.; Ksouri, R.

2017-01-01

Six medicinal halophytes widely represented in North Africa and commonly used in traditional medicine were screened for pharmacological properties to set out new promising sources of natural ingredients for cosmetic or nutraceutical applications. Thus, Citrullus colocynthis, Cleome arabica, Daemia cordata, Haloxylon articulatum, Pituranthos scoparius and Scorzonera undulata were examined for their in vitro antioxidant (DPPH scavenging and superoxide anion-scavenging, β-carotene bleaching inhibition and iron-reducing tests), antibacterial (microdilution method, against four human pathogenic bacteria) and anti-tyrosinase activities. Besides, their aromatic composition was determined by RP-HPLC. H. articulatum shoot extracts exhibited the strongest antioxidant activity and inhibited efficiently the growth of Salmonella enterica and Escherichia coli. P. scoparius and C. arabica inhibited slightly monophenolase, whereas H. articulatum was the most efficient inhibitor of diphenolase activity. Furthermore, H. articulatum exhibited the highest aromatic content (3.4 % DW), with dopamine as the major compound. These observations suggest that shoot extract of H. articulatum, and to a lesser extent of C. arabica, could be used as antioxidant, antibiotic as well as new natural skin lightening agents. Also, possible implication of aromatic compounds in anti-tyrosinase activity is discussed. PMID:28827992

Anti-aging activities of extracts from Tunisian medicinal halophytes and their aromatic constituents.

PubMed

Jdey, A; Falleh, H; Ben Jannet, S; Mkadmini Hammi, K; Dauvergne, X; Magné, C; Ksouri, R

2017-01-01

Six medicinal halophytes widely represented in North Africa and commonly used in traditional medicine were screened for pharmacological properties to set out new promising sources of natural ingredients for cosmetic or nutraceutical applications. Thus, Citrullus colocynthis , Cleome arabica , Daemia cordata , Haloxylon articulatum , Pituranthos scoparius and Scorzonera undulata were examined for their in vitro antioxidant (DPPH scavenging and superoxide anion-scavenging, β -carotene bleaching inhibition and iron-reducing tests), antibacterial (microdilution method, against four human pathogenic bacteria) and anti-tyrosinase activities. Besides, their aromatic composition was determined by RP-HPLC. H. articulatum shoot extracts exhibited the strongest antioxidant activity and inhibited efficiently the growth of Salmonella enterica and Escherichia coli . P. scoparius and C. arabica inhibited slightly monophenolase, whereas H. articulatum was the most efficient inhibitor of diphenolase activity. Furthermore, H. articulatum exhibited the highest aromatic content (3.4 % DW), with dopamine as the major compound. These observations suggest that shoot extract of H. articulatum , and to a lesser extent of C. arabica , could be used as antioxidant, antibiotic as well as new natural skin lightening agents. Also, possible implication of aromatic compounds in anti-tyrosinase activity is discussed.

Polyimidazoles Via Aromatic Nucleophilic Displacement

NASA Technical Reports Server (NTRS)

Connell, John W.; Hergenrother, Paul M.

1990-01-01

Experiments show variety of polyimidazoles prepared by aromatic nucleophilic displacement, from reactions of bisphenol imidazoles with activated difluoro compounds. Polyimidazoles have good mechanical properties making them suitable for use as films, moldings, and adhesives.

Aromatic residues located close to the active center are essential for the catalytic reaction of flap endonuclease-1 from hyperthermophilic archaeon Pyrococcus horikoshii.

PubMed

Matsui, Eriko; Abe, Junko; Yokoyama, Hideshi; Matsui, Ikuo

2004-04-16

Flap endonuclease-1 (FEN-1) possessing 5'-flap endonuclease and 5'-->3' exonuclease activity plays important roles in DNA replication and repair. In this study, the kinetic parameters of mutants at highly conserved aromatic residues, Tyr33, Phe35, Phe79, and Phe278-Phe279, in the vicinity of the catalytic centers of FEN-1 were examined. The substitution of these aromatic residues with alanine led to a large reduction in kcat values, although these mutants retained Km values similar to that of the wild-type enzyme. Notably, the kcat of Y33A and F79A decreased 333-fold and 71-fold, respectively, compared with that of the wild-type enzyme. The aromatic residues Tyr33 and Phe79, and the aromatic cluster Phe278-Phe279 mainly contributed to the recognition of the substrates without the 3' projection of the upstream strand (the nick, 5'-recess-end, single-flap, and pseudo-Y substrates) for the both exo- and endo-activities, but played minor roles in recognizing the substrates with the 3' projection (the double flap substrate and the nick substrate with the 3' projection). The replacement of Tyr33, Phe79, and Phe278-Phe279, with non-charged aromatic residues, but not with aliphatic hydrophobic residues, recovered the kcat values almost fully for the substrates without the 3' projection of the upstream strand, suggesting that the aromatic groups of Tyr33, Phe79, and Phe278-Phe279 might be involved in the catalytic reaction, probably via multiple stacking interactions with nucleotide bases. The stacking interactions of Tyr33 and Phe79 might play important roles in fixing the template strand and the downstream strand, respectively, in close proximity to the active center to achieve the productive transient state leading to the hydrolysis.

Nucleophilic Aromatic Substitution.

ERIC Educational Resources Information Center

Avila, Walter B.; And Others

1990-01-01

Described is a microscale organic chemistry experiment which demonstrates one feasible route in preparing ortho-substituted benzoic acids and provides an example of nucleophilic aromatic substitution chemistry. Experimental procedures and instructor notes for this activity are provided. (CW)

Conformation of the azo bond and its influence on the molecular and crystal structures, IR and Raman spectra, and electron properties of 6-methyl-3,5-dinitro-2-[(E)-phenyldiazenyl]pyridine - Quantum chemical DFT calculations.

PubMed

Michalski, J; Bryndal, I; Lorenc, J; Hermanowicz, K; Janczak, J; Hanuza, J

2018-02-15

The crystal and molecular structures of 6-methyl-3,5-dinitro-2-[(E)-phenyldiazenyl]pyridine have been determined by X-ray diffraction and quantum chemical DFT calculations. The crystal is monoclinic, space group Cc (No. 9) with Z=4 with the unit cell parameters: a=12.083(7), b=12.881(6), c=8.134(3) Å and β=97.09(5)°. The azo-bridge appears in the trans conformation in which C2-N2-N2'-C1' torsion angle takes a value -178.6(3)°, whereas the dihedral angle between the planes of the phenyl and pyridine rings is 3.5(2)°. The IR and Raman spectra measured in the temperature range 80-350K and quantum chemical calculations with the use of B3LYP/6-311G(2d,2p) approach confirmed the trans configuration of the azo-bridge as the most stable energetically and allowed determination of the energy other virtual structures. The observed effects were used in the discussion of vibrational dynamics of the studied compound. The energy gap between cis and trans conformers equals to 1.054eV (0.03873 Hartree). The electron absorption and emission spectra have been measured and analyzed on the basis of DFT calculations. The life time of the excited state is 12μs and the Stokes shift is close to 5470cm -1 . Copyright © 2017 Elsevier B.V. All rights reserved.

Conformation of the azo bond and its influence on the molecular and crystal structures, IR and Raman spectra, and electron properties of 6-methyl-3,5-dinitro-2-[(E)-phenyldiazenyl]pyridine - Quantum chemical DFT calculations

NASA Astrophysics Data System (ADS)

Michalski, J.; Bryndal, I.; Lorenc, J.; Hermanowicz, K.; Janczak, J.; Hanuza, J.

2018-02-01

The crystal and molecular structures of 6-methyl-3,5-dinitro-2-[(E)-phenyldiazenyl]pyridine have been determined by X-ray diffraction and quantum chemical DFT calculations. The crystal is monoclinic, space group Cc (No. 9) with Z = 4 with the unit cell parameters: a = 12.083(7), b = 12.881(6), c = 8.134(3) Å and β = 97.09(5)°. The azo-bridge appears in the trans conformation in which C2-N2-N2‧-C1‧ torsion angle takes a value - 178.6(3)°, whereas the dihedral angle between the planes of the phenyl and pyridine rings is 3.5(2)°. The IR and Raman spectra measured in the temperature range 80-350 K and quantum chemical calculations with the use of B3LYP/6-311G(2d,2p) approach confirmed the trans configuration of the azo-bridge as the most stable energetically and allowed determination of the energy other virtual structures. The observed effects were used in the discussion of vibrational dynamics of the studied compound. The energy gap between cis and trans conformers equals to 1.054 eV (0.03873 Hartree). The electron absorption and emission spectra have been measured and analyzed on the basis of DFT calculations. The life time of the excited state is 12 μs and the Stokes shift is close to 5470 cm- 1.

Biodegradation of hexahydro-1,3,5-trinitro-1,3,5-triazine and its mononitroso derivative hexahydro-1-nitroso-3,5-dinitro-1,3,5-triazine by Klebsiella pneumoniae strain SCZ-1 isolated from an anaerobic sludge.

PubMed

Zhao, Jian-Shen; Halasz, Annamaria; Paquet, Louise; Beaulieu, Chantale; Hawari, Jalal

2002-11-01

In previous work, we found that an anaerobic sludge efficiently degraded hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), but the role of isolates in the degradation process was unknown. Recently, we isolated a facultatively anaerobic bacterium, identified as Klebsiella pneumoniae strain SCZ-1, using MIDI and the 16S rRNA method from this sludge and employed it to degrade RDX. Strain SCZ-1 degraded RDX to formaldehyde (HCHO), methanol (CH3OH) (12% of total C), carbon dioxide (CO(2)) (72% of total C), and nitrous oxide (N2O) (60% of total N) through intermediary formation of methylenedinitramine (O(2)NNHCH(2)NHNO(2)). Likewise, hexahydro-1-nitroso-3,5-dinitro-1,3,5-triazine (MNX) was degraded to HCHO, CH3OH, and N2O (16.5%) with a removal rate (0.39 micromol. h(-1). g [dry weight] of cells(-1)) similar to that of RDX (0.41 micromol. h(-1). g [dry weight] of cells(-1)) (biomass, 0.91 g [dry weight] of cells. liter(-1)). These findings suggested the possible involvement of a common initial reaction, possibly denitration, followed by ring cleavage and decomposition in water. The trace amounts of MNX detected during RDX degradation and the trace amounts of hexahydro-1,3-dinitroso-5-nitro-1,3,5-triazine detected during MNX degradation suggested that another minor degradation pathway was also present that reduced -NO2 groups to the corresponding -NO groups.

Thermal reactivity of some nitro- and nitroso-compounds derived from 1,3,5,7-tetraazabicyclo[3.3.1]nonane at contamination by ammonium nitrate.

PubMed

Zeman, Svatopluk; Shu, Yuanjie; Friedl, Zdenek; Vágenknecht, Jirí

2005-05-20

Thermal reactivity of 3,7-dinitro-1,3,5,7-tetraazabicyclo[3.3.1]nonane (DPT), 3,7-dinitroso-1,3,5,7-tetraazabicyclo[3.3.1]nonane (DNPT), 1,3,5-trinitroso-1,3,5-triazinane (TMTA or R-salt), 1,3,5-trinitro-1,3,5-triazinane (hexogen or RDX), 1,5-diacetyl-3,7-dinitro-1,3,5,7-tetrazocane (DADN), alpha-modification of the 1,3,5,7-tetranitro-1,3,5,7-tetrazocane (octogen or HMX) and of their mixtures with 2wt.% of ammonium nitrate (AN) has been examined by means of non-isothermal differential thermal analysis. The resulting data were analyzed according to the Kissinger method. The reactivity was expressed as the E(a)R(-1) slopes of the Kissinger relationship. A relatively high reactivity has been found with mixtures of DPT and DNPT with AN. Electronic charges q(N) at nitrogen atoms in molecules of the compounds studied were calculated by means of ab initio DFT B3LYP/6-31G** method. The relationships were confirmed between the slopes E(a)R(-1) and the q(N) values for the nitrogen atoms primarily undergoing reaction. On the basis of these relationships it is stated that the destabilizing effect of AN is due to acidolytic attack of nitric acid (resulting from dissociation of ammonium nitrate) at the nitrogen atoms with the most negative q(N) values in the molecules of the compounds studied.

ortho- and meta-substituted aromatic thiols are efficient redox buffers that increase the folding rate of a disulfide-containing protein.

PubMed

Gough, Jonathan D; Barrett, Elvis J; Silva, Yenia; Lees, Watson J

2006-08-20

Thiol based redox buffers are used to enhance the folding rates of disulfide-containing proteins in vitro. Traditionally, small molecule aliphatic thiols such as glutathione are employed. Recently, we have demonstrated that aromatic thiols can further enhance protein-folding rates. In the presence of para-substituted aromatic thiols the folding rate of a disulfide-containing protein was increased by 4-23 times over that measured for glutathione. However, several important practical issues remain to be addressed. Aromatic thiols have never been tested in the presence of denaturants such as guanidine hydrochloride. Only two of the para-substituted aromatic thiols previously examined are commercially available. To expand the number of aromatic thiols for protein folding, several commercially available meta- and ortho-substituted aromatic thiols were studied. Furthermore, an ortho-substituted aromatic thiol, easily obtained from inexpensive starting materials, was investigated. Folding rates of scrambled ribonuclease A at pH 6.0, 7.0 and 7.7, with ortho- and meta-substituted aromatic thiols, were up to 10 times greater than those with glutathione. In the presence of the common denaturant guanidine hydrochloride (0.5M) aromatic thiols provided 100% yield of active protein while maintaining equivalent folding rates.

Oxygen activation by mononuclear nonheme iron dioxygenases involved in the degradation of aromatics.

PubMed

Wang, Yifan; Li, Jiasong; Liu, Aimin

2017-04-01

Molecular oxygen is utilized in numerous metabolic pathways fundamental for life. Mononuclear nonheme iron-dependent oxygenase enzymes are well known for their involvement in some of these pathways, activating O 2 so that oxygen atoms can be incorporated into their primary substrates. These reactions often initiate pathways that allow organisms to use stable organic molecules as sources of carbon and energy for growth. From the myriad of reactions in which these enzymes are involved, this perspective recounts the general mechanisms of aromatic dihydroxylation and oxidative ring cleavage, both of which are ubiquitous chemical reactions found in life-sustaining processes. The organic substrate provides all four electrons required for oxygen activation and insertion in the reactions mediated by extradiol and intradiol ring-cleaving catechol dioxygenases. In contrast, two of the electrons are provided by NADH in the cis-dihydroxylation mechanism of Rieske dioxygenases. The catalytic nonheme Fe center, with the aid of active site residues, facilitates these electron transfers to O 2 as key elements of the activation processes. This review discusses some general questions for the catalytic strategies of oxygen activation and insertion into aromatic compounds employed by mononuclear nonheme iron-dependent dioxygenases. These include: (1) how oxygen is activated, (2) whether there are common intermediates before oxygen transfer to the aromatic substrate, and (3) are these key intermediates unique to mononuclear nonheme iron dioxygenases?

Synthesis of tetra- and octa-aurated heteroaryl complexes towards probing aromatic indoliums

PubMed Central

Yuan, Jun; Sun, Tingting; He, Xin; An, Ke; Zhu, Jun; Zhao, Liang

2016-01-01

Polymetalated aromatic compounds are particularly challenging synthetic goals because of the limited thermodynamic stability of polyanionic species arising from strong electrostatic repulsion between adjacent carbanionic sites. Here we describe a facile synthesis of two polyaurated complexes including a tetra-aurated indole and an octa-aurated benzodipyrrole. The imido trinuclear gold(I) moiety exhibits nucleophilicity and undergoes an intramolecular attack on a gold(I)-activated ethynyl to generate polyanionic heteroaryl species. Their computed magnetic properties reveal the aromatic character in the five-membered ring. The incorporation of the aurated substituents at the nitrogen atom can convert non-aromaticity in the parent indolium into aromaticity in the aurated one because of hyperconjugation. Thus, the concept of hyperconjugative aromaticity is extended to heterocycles with transition metal substituents. More importantly, further analysis indicates that the aurated substituents can perform better than traditional main-group substituents. This work highlights the difference in aromaticity between polymetalated aryls and their organic prototypes. PMID:27186982

Biodegradation of high-molecular-weight polycyclic aromatic hydrocarbons under anaerobic conditions: Overview of studies, proposed pathways and future perspectives.

PubMed

Nzila, Alexis

2018-05-07

The biodegradation of low- and high-molecular-weight polycyclic aromatic hydrocarbons (PAHs) (LWM-PAHs and HMW-PAHs, respectively) has been studied extensively under aerobic conditions. Molecular O 2 plays 2 critical roles in this biodegradation process. O 2 activates the aromatic rings through hydroxylation prior to ring opening and serves as a terminal electron acceptor (TEA). However, several microorganisms have devised ways of activating aromatic rings, leading to ring opening (and thus biodegradation) when TEAs other than O 2 are used (under anoxic conditions). These microorganisms belong to the sulfate-, nitrate-, and metal-ion-reducing bacteria and the methanogens. Although the anaerobic biodegradation of monocyclic aromatic hydrocarbons and LWM-PAH naphthalene have been studied, little information is available about the biodegradation of HMW-PAHs. This manuscript reviews studies of the anaerobic biodegradation of HMW-PAHs and identifies gaps that limit both our understanding and the efficiency of this biodegradation process. Strategies that can be employed to overcome these limitations are also discussed. Copyright © 2018 Elsevier Ltd. All rights reserved.

Extending (Q)SARs to incorporate proprietary knowledge for regulatory purposes: A case study using aromatic amine mutagenicity.

PubMed

Ahlberg, Ernst; Amberg, Alexander; Beilke, Lisa D; Bower, David; Cross, Kevin P; Custer, Laura; Ford, Kevin A; Van Gompel, Jacky; Harvey, James; Honma, Masamitsu; Jolly, Robert; Joossens, Elisabeth; Kemper, Raymond A; Kenyon, Michelle; Kruhlak, Naomi; Kuhnke, Lara; Leavitt, Penny; Naven, Russell; Neilan, Claire; Quigley, Donald P; Shuey, Dana; Spirkl, Hans-Peter; Stavitskaya, Lidiya; Teasdale, Andrew; White, Angela; Wichard, Joerg; Zwickl, Craig; Myatt, Glenn J

2016-06-01

Statistical-based and expert rule-based models built using public domain mutagenicity knowledge and data are routinely used for computational (Q)SAR assessments of pharmaceutical impurities in line with the approach recommended in the ICH M7 guideline. Knowledge from proprietary corporate mutagenicity databases could be used to increase the predictive performance for selected chemical classes as well as expand the applicability domain of these (Q)SAR models. This paper outlines a mechanism for sharing knowledge without the release of proprietary data. Primary aromatic amine mutagenicity was selected as a case study because this chemical class is often encountered in pharmaceutical impurity analysis and mutagenicity of aromatic amines is currently difficult to predict. As part of this analysis, a series of aromatic amine substructures were defined and the number of mutagenic and non-mutagenic examples for each chemical substructure calculated across a series of public and proprietary mutagenicity databases. This information was pooled across all sources to identify structural classes that activate or deactivate aromatic amine mutagenicity. This structure activity knowledge, in combination with newly released primary aromatic amine data, was incorporated into Leadscope's expert rule-based and statistical-based (Q)SAR models where increased predictive performance was demonstrated. Copyright © 2016 Elsevier Inc. All rights reserved.

Identification of acidic and aromatic residues in the Zta activation domain essential for Epstein-Barr virus reactivation.

PubMed

Deng, Z; Chen, C J; Zerby, D; Delecluse, H J; Lieberman, P M

2001-11-01

Epstein-Barr virus (EBV) lytic cycle transcription and DNA replication require the transcriptional activation function of the viral immediate-early protein Zta. We describe a series of alanine substitution mutations in the Zta activation domain that reveal two functional motifs based on amino acid composition. Alanine substitution of single or paired hydrophobic aromatic amino acid residues resulted in modest transcription activation defects, while combining four substitutions of aromatic residues (F22/F26/W74/F75) led to more severe transcription defects. Substitution of acidic amino acid residue E27, D35, or E54 caused severe transcription defects on most viral promoters. Promoter- and cell-specific defects were observed for some substitution mutants. Aromatic residues were required for Zta interaction with TFIIA-TFIID and the CREB-binding protein (CBP) and for stimulation of CBP histone acetyltransferase activity in vitro. In contrast, acidic amino acid substitution mutants interacted with TFIIA-TFIID and CBP indistinguishably from the wild type. The nuclear domain 10 (ND10) protein SP100 was dispersed by most Zta mutants, but acidic residue mutations led to reduced, while aromatic substitution mutants led to increased SP100 nuclear staining. Acidic residue substitution mutants had more pronounced defects in transcription activation of endogenous viral genes in latently infected cells and for viral replication, as measured by the production of infectious virus. One mutant, K12/F13, was incapable of stimulating EBV lytic replication but had only modest transcription defects. These results indicate that Zta stimulates viral reactivation through two nonredundant structural motifs, one of which interacts with general transcription factors and coactivators, and the other has an essential but as yet not understood function in lytic transcription.

Characterization of the oestrogenic activity of non-aromatic steroids: are there male-specific endogenous oestrogen receptor modulators?

PubMed Central

Wang, Pan; Wen, Yujing; Han, Gui-Zhen; Sidhu, Pritam Kaur; Zhu, Bao Ting

2009-01-01

Background and purpose: The endogenous oestrogens have important biological functions in men as well as in women. Because 17β-oestradiol and oestrone are also formed in the male body, these aromatic oestrogens are generally thought to be responsible for exerting the required oestrogenic functions in the male. In the present study, we tested the hypothesis that some of the non-aromatic steroids that are androgen precursors or metabolites with hydroxyl groups at C-3 and/or C-17 positions may also be able to serve as ligands for the oestrogen receptors (ER) in the male. Experimental approach: A total of sixty non-aromatic steroids (selected from families of androstens, androstans, androstadiens, oestrens and oestrans) were analysed for their ability to bind and activate the human ERα and ERβin vitro and in cultured cells. Key results: Six of the non-aromatic steroids, that is, 5-androsten-3β,17β-diol, 5α-androstan-3β,17β-diol, 5(10)-oestren-3α,17β-diol, 5(10)-oestren-3β,17β-diol, 4-oestren-3β,17β-diol and 5α-oestran-3β,17β-diol, were found to have physiologically relevant high binding affinity (∼50% of that of oestrone) for human ERα and ERβ. These non-aromatic steroids also activated the transcriptional activity of human ERs and elicited biological responses (such as growth stimulation) in two representative ER-positive human cancer cell lines (MCF-7 and LNCaP) with physiologically relevant potency and efficacy. Molecular docking analysis of these six active compounds showed that they could bind to ERα and ERβ in a manner similar to that of 17β-oestradiol. Conclusions and implications: These results provide evidence for the possibility that some of the endogenous androgen precursors or metabolites could serve as male-specific ER ligands. PMID:19888961

(Hetero)aromatics from dienynes, enediynes and enyne-allenes.

PubMed

Raviola, Carlotta; Protti, Stefano; Ravelli, Davide; Fagnoni, Maurizio

2016-08-07

The construction of aromatic rings has become a key objective for organic chemists. While several strategies have been developed for the functionalization of pre-formed aromatic rings, the direct construction of an aromatic core starting from polyunsaturated systems is yet a less explored field. The potential of such reactions in the formation of aromatics increased at a regular pace in the last few years. Nowadays, there are reliable and well-established procedures to prepare polyenic derivatives, such as dienynes, enediynes, enyne-allenes and hetero-analogues. This has stimulated their use in the development of innovative cycloaromatizations. Different examples have recently emerged, suggesting large potential of this strategy in the preparation of (hetero)aromatics. Accordingly, this review highlights the recent advancements in this field and describes the different conditions exploited to trigger the process, including thermal and photochemical activation, as well as the use of transition metal catalysis and the addition of electrophiles/nucleophiles or radical species.

Toxicity of N-substituted aromatics to acetoclastic methanogenic activity in granular sludge

DOE Office of Scientific and Technical Information (OSTI.GOV)

Donlon, B.A.; Razo-Flores, E.; Field, J.A.

1995-11-01

N-substituted aromatics are important priority pollutants entering the environment primarily through anthropogenic activities associated associated with the industrial production of dyes, explosives, pestides, and pharmaceuticals. Anaerobic treatment of wastewaters discharged by these industries could potentially be problematical as a result of the high toxicity of N-substituted aromatics. The objective of this study was to examine the structure-toxicity relationship of N-substituted aromatic compounds to acetoclastic methanogenic bacteria. The toxicity was assayed to serum flasks by measuring methane production in granular sludge. Unacclimated cultures were used to minimize the biotransformation of the toxic organic chemicals during the test. The nature and themore » degree of the aromatic substitution were observed to have a profound effect on the toxicity of the test compound. Nitroaromatic compounds were, on the average, over 500-fold more toxic than their corresponding aromatic amines. Considering the facile reduction of nitro groups by anerobic microorganisms, a dramatic detoxification of nitroaromatics towards methanogens can be expected to occur during anaerobic wastewater treatment. While the toxicity exerted by the N-substituted aromatic compounds was closely correlated with compound apolarity (log P), it was observed that at any given log P, N-substituted phenols had a toxicity that was 2 orders of magnitude higher than that of chlorophenols and alkylphenols. This indicates that toxicity due to the chemical reactivity of nitroaromatics is much more important than partitioning effects in bacterial membranes. 41 refs., 3 figs., 1 tab.« less

1-(4,5-Dinitro-10-aza­tricyclo­[6.3.1.02,7]dodeca-2,4,6-trien-10-yl)-2,2,2-trifluoro­ethanone

PubMed Central

Xu, Hao; Quan, Ji-Cai; Xu, Jian; Chen, Jing; Wang, Jin-Tang

2008-01-01

In the title compound, C13H10F3N3O5, a derivative of andrographolide, the five-membered ring adopts an envelope conformation, while the non-planar six-membered ring has a chair conformation. An intra­molecular C—H⋯F hydrogen bond results in the formation of a non-planar six-membered ring adopting a twisted conformation. In the crystal structure, inter­molecular C—H⋯O hydrogen bonds link the mol­ecules into centrosymmetric dimers. PMID:21581393

Potential contributions of smectite clays and organic matter to pesticide retention in soils.

PubMed

Sheng, G; Johnston, C T; Teppen, B J; Boyd, S A

2001-06-01

Soil organic matter (SOM) is often considered the dominant sorptive phase for organic contaminants and pesticides in soil-water systems. This is evidenced by the widespread use of organic-matter-normalized sorption coefficients (K(OM)) to predict soil-water distribution of pesticides, an approach that ignores the potential contribution of soil minerals to sorption. To gain additional perspective on the potential contributions of clays and SOM to pesticide retention in soils, we measured sorption of seven pesticides by a K-saturated reference smectite clay (SWy-2) and SOM (represented by a muck soil). In addition, we measured the adsorption of atrazine by five different K-saturated smectites and Ca-saturated SWy-2. On a unit mass basis, the K-SWy-2 clay was a more effective sorbent than SOM for 4,6-dinitro-o-cresol (DNOC), dichlobenil, and carbaryl of the seven pesticides evaluated, of which, DNOC was sorbed to the greatest extent. Atrazine was sorbed to a similar extent by K-SWy-2 and SOM. Parathion, diuron, and biphenyl were sorbed to a greater extent by SOM than by K-SWy-2. Atrazine was adsorbed by Ca-SWy-2 to a much lesser extent than by K-SWy-2. This appears to be related to the larger hydration sphere of Ca(2+) (compared to that of K(+)) which shrinks the effective size of the adsorption domains between exchangeable cations, and which expands the clay layers beyond the apparently optimal spacing of approximately 12.2 A for sorption of aromatic pesticide structures. Although a simple relation between atrazine adsorption by different K-smectites and charge properties of clay was not observed, the highest charge clay was the least effective sorbent; a higher charge density would result in a loss of adsorption domains. These results indicate that for certain pesticides, expandable soil clays have the potential to be an equal or dominant sorptive phase when compared to SOM for pesticide retention in soil.

Synthesis and antibacterial activity of aromatic and heteroaromatic amino alcohols.

PubMed

de Almeida, Camila G; Reis, Samira G; de Almeida, Angelina M; Diniz, Claudio G; da Silva, Vânia L; Le Hyaric, Mireille

2011-11-01

Two series of aromatic and heteroaromatic amino alcohols were synthesized from alcohols and aldehydes and evaluated for their antibacterial activities. All the octylated compounds displayed a better activity against the four bacteria tested when evaluated by the agar diffusion method and were selected for the evaluation of minimal inhibitory concentration. The best results were obtained for p-octyloxybenzyl derivatives against Staphylococcus epidermidis (minimal inhibitory concentrations = 32 μm). © 2011 John Wiley & Sons A/S.

An ethnopharmacological study of aromatic Uyghur medicinal plants in Xinjiang, China.

PubMed

Zhao, Lu; Tian, Shuge; Wen, E; Upur, Halmuart

2017-12-01

An ethnobotanical survey was completed in a remote village and surrounding country of Xinjiang, where most Uyghur medicinal plants could be collected. This work clarifies and increases ethnobotanical data. We surveyed and organized aromatic medicinal plants that are commonly used in clinical settings to provide a significant reference for studying new medical activities. In the survey, informants who have traditional knowledge on aromatic Uyghur medicinal plants were interviewed between March 2014 and September 2014. Aromatic medicinal plant species and pertinent information were collected. Some therapeutic methods and modes of preparation of traditional aromatic medicinal plants were found. A total of 86 aromatic medicinal plant species belonging to 36 families were included in our study. We identified 34 plant species introduced from different regions such as Europe, India and Mediterranean areas. Fruits and whole plants were the most commonly used parts of plant, and most aromatic medicinal plants could be applied as medicine and food. We assigned the medicinal plants a use value (UV). Knowing the UV of species is useful in determining the use reliability and pharmacological features of related plants. Xinjiang is an area in which indigenous aromatic medicinal plants are diversely used and has therefore established a sound dimensional medical healthcare treatment system. Some aromatic Uyghur medicinal plants are on the verge of extinction. Hence, further strategies for the conservation of these aromatic medicinal plants should be prioritized.

A NOVEL METABOLIC ACTIVATION PATHWAY FOR POLYCYCLIC AROMATIC HYDROCARBONS: REACTIVE OXYGEN SPECIES-MEDIATED DNA DAMAGE AND MORPHOLOGICAL CELL TRANSFORMATION IN MOUSE EMBRYO CELLS BY K-REGION DIOL METABOLITES

EPA Science Inventory

Benzo[ a ]pyrene (BP) is a well-studied polycyclic aromatic hydrocarbon (P AH) .Many
mechanisms have been suggested to explain its carcinogenic activity, yet many questions still
remain. K-region dihydrodiols (diols) ofPAHs are common metabolites and some are genotoxic. W...

Isotopic exchange of hydrogen in aromatic amino acids

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pshenichnikova, A.B.; Karnaukhova, E.N.; Mitsner, B.I.

The kinetics of the isotopic replacement of hydrogen in the aromatic amino acids L-tryptophan, L-tyrosine, and L-phenylalanine in solutions of deuterochloric and deuterosulfuric acids in deuterium oxide were investigated by PMR spectroscopy. The reactions were shown to be of first orders with respect both to the concentration of the substrate and to the activity of the deuterium ion. The isotopic effects of hydrogen and the values of the activation energy of H-D exchange in different positions of the aromatic ring in tryptophan and tyrosine were determined. The effect of properties of the medium on the rate of the isotopic exchangemore » of hydrogen is discussed. 17 refs., 2 figs., 2 tabs.« less

In Vitro Antifungal Activity of New and Known Geranylated Phenols against Phytophthora cinnamomi Rands.

PubMed

Chavez, María I; Soto, Mauricio; Cimino, Franco A; Olea, Andrés F; Espinoza, Luis; Díaz, Katy; Taborga, Lautaro

2018-05-29

A series of new and known geranylated phenol/methoxyphenol derivatives has been tested in vitro as inhibitor agents of mycelial growth of Phytophthora cinnamomi . The activity of tested compounds is correlated with the nature, number, and position of the substituent group on the aromatic ring. Results indicate that the most active geranylated derivatives are those having two hydroxyl groups (or one ⁻OH and one ⁻OCH₃) attached to the aromatic ring. Interestingly, these derivatives are as active as Metalaxil ® , a commonly used commercial fungicide. Thus, our results suggest that some of these compounds might be of agricultural interest due to their potential use as fungicides against P. cinnamomi . The effect of structure on fungicide activity is discussed in terms of electronic distribution on both the aromatic ring and side geranyl chain. All tested compounds have been synthesized by direct coupling of geraniol and the respective phenol. Interestingly, new digeranylated derivatives were obtained by increasing the reaction time.

The Aspergillus niger faeB gene encodes a second feruloyl esterase involved in pectin and xylan degradation and is specifically induced in the presence of aromatic compounds.

PubMed

de Vries, Ronald P; vanKuyk, Patricia A; Kester, Harry C M; Visser, Jaap

2002-04-15

The faeB gene encoding a second feruloyl esterase from Aspergillus niger has been cloned and characterized. It consists of an open reading frame of 1644 bp containing one intron. The gene encodes a protein of 521 amino acids that has sequence similarity to that of an Aspergillus oryzae tannase. However, the encoded enzyme, feruloyl esterase B (FAEB), does not have tannase activity. Comparison of the physical characteristics and substrate specificity of FAEB with those of a cinnamoyl esterase from A. niger [Kroon, Faulds and Williamson (1996) Biotechnol. Appl. Biochem. 23, 255-262] suggests that they are in fact the same enzyme. The expression of faeB is specifically induced in the presence of certain aromatic compounds, but not in the presence of other constituents present in plant-cell-wall polysaccharides such as arabinoxylan or pectin. The expression profile of faeB in the presence of aromatic compounds was compared with the expression of A. niger faeA, encoding feruloyl esterase A (FAEA), and A. niger bphA, the gene encoding a benzoate-p-hydroxylase. All three genes have different subsets of aromatic compounds that induce their expression, indicating the presence of different transcription activating systems in A. niger that respond to aromatic compounds. Comparison of the activity of FAEA and FAEB on sugar-beet pectin and wheat arabinoxylan demonstrated that they are both involved in the degradation of both polysaccharides, but have opposite preferences for these substrates. FAEA is more active than FAEB towards wheat arabinoxylan, whereas FAEB is more active than FAEA towards sugar-beet pectin.

The Aspergillus niger faeB gene encodes a second feruloyl esterase involved in pectin and xylan degradation and is specifically induced in the presence of aromatic compounds.

PubMed Central

de Vries, Ronald P; vanKuyk, Patricia A; Kester, Harry C M; Visser, Jaap

2002-01-01

The faeB gene encoding a second feruloyl esterase from Aspergillus niger has been cloned and characterized. It consists of an open reading frame of 1644 bp containing one intron. The gene encodes a protein of 521 amino acids that has sequence similarity to that of an Aspergillus oryzae tannase. However, the encoded enzyme, feruloyl esterase B (FAEB), does not have tannase activity. Comparison of the physical characteristics and substrate specificity of FAEB with those of a cinnamoyl esterase from A. niger [Kroon, Faulds and Williamson (1996) Biotechnol. Appl. Biochem. 23, 255-262] suggests that they are in fact the same enzyme. The expression of faeB is specifically induced in the presence of certain aromatic compounds, but not in the presence of other constituents present in plant-cell-wall polysaccharides such as arabinoxylan or pectin. The expression profile of faeB in the presence of aromatic compounds was compared with the expression of A. niger faeA, encoding feruloyl esterase A (FAEA), and A. niger bphA, the gene encoding a benzoate-p-hydroxylase. All three genes have different subsets of aromatic compounds that induce their expression, indicating the presence of different transcription activating systems in A. niger that respond to aromatic compounds. Comparison of the activity of FAEA and FAEB on sugar-beet pectin and wheat arabinoxylan demonstrated that they are both involved in the degradation of both polysaccharides, but have opposite preferences for these substrates. FAEA is more active than FAEB towards wheat arabinoxylan, whereas FAEB is more active than FAEA towards sugar-beet pectin. PMID:11931668

Comparison of carbon-sulfur and carbon-amine bond in therapeutic drug: 4β-S-aromatic heterocyclic podophyllum derivatives display antitumor activity

PubMed Central

Li, Jian-Long; Zhao, Wei; Zhou, Chen; Zhang, Ya-Xuan; Li, Hong-Mei; Tang, Ya-Ling; Liang, Xin-Hua; Chen, Tao; Tang, Ya-Jie

2015-01-01

Herein is a first effort to systematically study the significance of carbon-sulfur (C-S) and carbon-amine (C-NH) bonds on the antitumor proliferation activity of podophyllum derivatives and their precise mechanism of apoptosis. Compared with the derivative modified by a C-NH bond, the derivative modified by a C-S bond exhibited superior antitumor activity, the inhibition activity of target proteins tubulin or Topo II, cell cycle arrest, and apoptosis induction. Antitumor mechanistic studies showed that the death receptor and the mitochondrial apoptotic pathways were simultaneously activated by the C-S bond modified aromatic heterocyclic podophyllum derivatives with a higher cellular uptake percentage of 60–90% and induction of a higher level of reactive oxygen species (ROS). Only the mitochondrial apoptotic pathway was activated by the C-NH bond modified aromatic heterocyclic podophyllum derivatives, with a lower cellular uptake percentage of 40–50%. This study provided insight into effects of the C-S and C-NH bond modification on the improvement of the antitumor activity of Podophyllum derivatives. PMID:26443888

Oxidation of aromatic contaminants coupled to microbial iron reduction

USGS Publications Warehouse

Lovley, D.R.; Baedecker, M.J.; Lonergan, D.J.; Cozzarelli, I.M.; Phillips, E.J.P.; Siegel, D.I.

1989-01-01

THE contamination of sub-surface water supplies with aromatic compounds is a significant environmental concern1,2. As these contaminated sub-surface environments are generally anaerobic, the microbial oxidation of aromatic compounds coupled to nitrate reduction, sulphate reduction and methane production has been studied intensively1-7. In addition, geochemical evidence suggests that Fe(III) can be an important electron acceptor for the oxidation of aromatic compounds in anaerobic groundwater. Until now, only abiological mechanisms for the oxidation of aromatic compounds with Fe(III) have been reported8-12. Here we show that in aquatic sediments, microbial activity is necessary for the oxidation of model aromatic compounds coupled to Fe(III) reduction. Furthermore, a pure culture of the Fe(III)-reducing bacterium GS-15 can obtain energy for growth by oxidizing benzoate, toluene, phenol or p-cresol with Fe(III) as the sole electron acceptor. These results extend the known physiological capabilities of Fe(III)-reducing organisms and provide the first example of an organism of any type which can oxidize an aromatic hydrocarbon anaerobically. ?? 1989 Nature Publishing Group.

Aromatic hydrocarbons from the Middle Jurassic fossil wood of the Polish Jura

NASA Astrophysics Data System (ADS)

Smolarek, Justyna; Marynowski, Leszek

2013-09-01

Aromatic hydrocarbons are present in the fossil wood samples in relatively small amounts. In almost all of the tested samples the dominating aromatic hydrocarbon is perylene and its methyl and dimethyl derivatives. The most important biomarkers present in the aromatic fraction are dehydroabietane, siomonellite and retene, compounds characteristic for conifers. The distribution of discussed compounds is highly variable due to such early diagenetic processes affecting the wood as oxidation and the activity of microorganisms. MPI1 parameter values (methylphenanthrene index) for the majority of the samples are in the range of 0.1 to 0.5, which results in the highly variable values of Rc (converted value of vitrinite reflectance) ranging from 0.45 to 0.70%. Such values suggest that MPI1 parameter is not useful as maturity parameter in case of Middle Jurassic ore-bearing clays, even if measured strictly on terrestrial organic matter (OM). As a result of weathering processes (oxidation) the distribution of aromatic hydrocarbons changes. In the oxidized samples the amount of aromatic hydrocarbons, both polycyclic as well as aromatic biomarkers decreases.

Structure-activity relationship and docking studies of thiazolidinedione-type compounds with monoamine oxidase B.

PubMed

Carroll, Richard T; Dluzen, Dean E; Stinnett, Hilary; Awale, Prabha S; Funk, Max O; Geldenhuys, Werner J

2011-08-15

The neuroprotective activity of pioglitazone and rosiglitazone in the MPTP parkinsonian mouse prompted us to evaluate a set of thiazolidinedione (TZD) type compounds for monoamine oxidase A and B inhibition activity. These compounds were able to inhibit MAO-B over several log units of magnitude (82 nM to 600 μM). Initial structure-activity relationship studies identified key areas to modify the aromatic substituted TZD compounds. Primarily, substitutions on the aromatic group and the TZD nitrogen were key areas where activity was enhanced within this group of compounds. Copyright © 2011 Elsevier Ltd. All rights reserved.

Polycyclic Aromatic Hydrocarbons: A Critical Review of Environmental Occurrence and Bioremediation.

PubMed

Alegbeleye, Oluwadara Oluwaseun; Opeolu, Beatrice Oluwatoyin; Jackson, Vanessa Angela

2017-10-01

The degree of polycyclic aromatic hydrocarbon contamination of environmental matrices has increased over the last several years due to increase in industrial activities. Interest has surrounded the occurrence and distribution of polycyclic aromatic hydrocarbons for many decades because they pose a serious threat to the health of humans and ecosystems. The importance of the need for sustainable abatement strategies to alleviate contamination therefore cannot be overemphasised, as daily human activities continue to create pollution from polycyclic aromatic hydrocarbons and impact the natural environment. Globally, attempts have been made to design treatment schemes for the remediation and restoration of contaminated sites. Several techniques and technologies have been proposed and tested over time, the majority of which have significant limitations. This has necessitated research into environmentally friendly and cost-effective clean-up techniques. Bioremediation is an appealing option that has been extensively researched and adopted as it has been proven to be relatively cost-effective, environmentally friendly and is publicly accepted. In this review, the physicochemical properties of some priority polycyclic aromatic hydrocarbons, as well as the pathways and mechanisms through which they enter the soil, river systems, drinking water, groundwater and food are succinctly examined. Their effects on human health, other living organisms, the aquatic ecosystem, as well as soil microbiota are also elucidated. The persistence and bioavailability of polycyclic aromatic hydrocarbons are discussed as well, as they are important factors that influence the rate, efficiency and overall success of remediation. Bioremediation (aerobic and anaerobic), use of biosurfactants and bioreactors, as well as the roles of biofilms in the biological treatment of polycyclic aromatic hydrocarbons are also explored.

Polycyclic Aromatic Hydrocarbons: A Critical Review of Environmental Occurrence and Bioremediation

NASA Astrophysics Data System (ADS)

Alegbeleye, Oluwadara Oluwaseun; Opeolu, Beatrice Oluwatoyin; Jackson, Vanessa Angela

2017-10-01

The degree of polycyclic aromatic hydrocarbon contamination of environmental matrices has increased over the last several years due to increase in industrial activities. Interest has surrounded the occurrence and distribution of polycyclic aromatic hydrocarbons for many decades because they pose a serious threat to the health of humans and ecosystems. The importance of the need for sustainable abatement strategies to alleviate contamination therefore cannot be overemphasised, as daily human activities continue to create pollution from polycyclic aromatic hydrocarbons and impact the natural environment. Globally, attempts have been made to design treatment schemes for the remediation and restoration of contaminated sites. Several techniques and technologies have been proposed and tested over time, the majority of which have significant limitations. This has necessitated research into environmentally friendly and cost-effective clean-up techniques. Bioremediation is an appealing option that has been extensively researched and adopted as it has been proven to be relatively cost-effective, environmentally friendly and is publicly accepted. In this review, the physicochemical properties of some priority polycyclic aromatic hydrocarbons, as well as the pathways and mechanisms through which they enter the soil, river systems, drinking water, groundwater and food are succinctly examined. Their effects on human health, other living organisms, the aquatic ecosystem, as well as soil microbiota are also elucidated. The persistence and bioavailability of polycyclic aromatic hydrocarbons are discussed as well, as they are important factors that influence the rate, efficiency and overall success of remediation. Bioremediation (aerobic and anaerobic), use of biosurfactants and bioreactors, as well as the roles of biofilms in the biological treatment of polycyclic aromatic hydrocarbons are also explored.

COMPUTATIONAL METHODS FOR STUDYING THE INTERACTION BETWEEN POLYCYCLIC AROMATIC HYDROCARBONS AND BIOLOGICAL MACROMOLECULES

EPA Science Inventory

Computational Methods for Studying the Interaction between Polycyclic Aromatic Hydrocarbons and Biological Macromolecules .

The mechanisms for the processes that result in significant biological activity of PAHs depend on the interaction of these molecules or their metabol...

Preparation and application of sustained release microcapsules of potassium ferrate(VI) for dinitro butyl phenol (DNBP) wastewater treatment.

PubMed

Wang, Hui-Long; Liu, Shu-Qin; Zhang, Xiu-Yan

2009-09-30

The encapsulated potassium ferrate(VI) (K(2)FeO(4)) samples were successfully prepared by phase separation method in organic solvents. The ethyl cellulose and paraffin were selected for the microcapsule wall materials (WM). The as prepared microcapsules were characterized by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). The stability can be enhanced greatly when ferrate(VI) was encapsulated in the microcapsules with a mass ratio of Fe(VI):WM in the range of 1:1-1:3 for the same conserved time in air compared for pure K(2)FeO(4). The sustained release behavior of the microcapsules with different Fe(VI):WM mass ratios in 8.0M KOH solution was also investigated. The results indicated that the Fe(VI) release was reduced with increase of Fe(VI):WM mass ratios from 1:1 to 1:3. The release kinetics of the microcapsules is found to obey Ritger-Peppas equation. The prepared Fe(VI) microcapsules has been used for the removal of a typical alkyl dinitro phenol compound, 2-sec-butyl-4,6-dinitrophenol (DNBP), from aqueous solution. The effect of pH, microcapsule concentration and reaction time was studied thoroughly. The optimal pH for DNBP degradation was 6.5, and at this pH and a microcapsule concentration of 1.2g/L, approximately 93% of the DNBP was degraded after 80 min. The encapsulated ferrate(VI) samples were found to be very effective in the decolorization and COD reduction of real wastewater from DNBP manufacturing. Thus, this study showed the feasible and potential use of encapsulated Fe(VI) samples in degradation of various toxic organic contaminants and industrial effluents.

Co-aromatization of olefin and methane over Ag-Ga/ZSM-5 catalyst at low temperature

DOE Office of Scientific and Technical Information (OSTI.GOV)

He, Peng; Gatip, Richard; Yung, Matthew

The massive exploitation of shale gas in the past decade has boosted the production of natural gas and reduced its price dramatically. The methane activation and following conversion into more valuable fuels and chemicals have thus become more and more attractive, while the introduction of hydrocarbons to enhance the methane activation at mild conditions represents a promising approach. In the present work, the co-aromatization of methane with propylene has been studied at 400 °C. The presence of methane would increase the toluene to benzene ratio as well as the average carbon number of the formed liquid aromatic products compared tomore » its propylene alone counterpart. Among the gas products, the formations of C 3H 8, C 4H 8 and C 4H 10 also get promoted when methane is present. The incorporation of methane into the product molecules is also directly evidenced by the 1H, 2D and 13C NMR spectroscopy of the liquid products obtained from the reaction between propylene (or styrene) and isotope labelled methane. Hydrogen from methane would contribute a large portion of the hydrogen in the product molecules, while the benzylic and aromatic hydrogen sites are favored compared with those on the alkyl side chains. The activation of methane is also observed in the DRIFT spectra when deuterium enriched methane is engaged as the methane source and evidenced by the escalated exothermic feature when olefin aromatization takes place under methane environment. The excellent catalytic performance of Ag-Ga/ZSM-5 might be because of the better dispersion of Ag and Ga on the ZSM-5 surface and moderate amount of strong Brosted and Lewis surface acid sites. All the observations suggest that methane might be activated nonoxidatively and converted into aromatics if suitable catalyst is charged under the assistance of co-existing olefin. In conclusion, the reported synergetic effect could potentially lead to the more economic utilization of abundant natural gas and petrochemical intermediates.« less

Co-aromatization of olefin and methane over Ag-Ga/ZSM-5 catalyst at low temperature

DOE PAGES

He, Peng; Gatip, Richard; Yung, Matthew; ...

2017-04-22

The massive exploitation of shale gas in the past decade has boosted the production of natural gas and reduced its price dramatically. The methane activation and following conversion into more valuable fuels and chemicals have thus become more and more attractive, while the introduction of hydrocarbons to enhance the methane activation at mild conditions represents a promising approach. In the present work, the co-aromatization of methane with propylene has been studied at 400 °C. The presence of methane would increase the toluene to benzene ratio as well as the average carbon number of the formed liquid aromatic products compared tomore » its propylene alone counterpart. Among the gas products, the formations of C 3H 8, C 4H 8 and C 4H 10 also get promoted when methane is present. The incorporation of methane into the product molecules is also directly evidenced by the 1H, 2D and 13C NMR spectroscopy of the liquid products obtained from the reaction between propylene (or styrene) and isotope labelled methane. Hydrogen from methane would contribute a large portion of the hydrogen in the product molecules, while the benzylic and aromatic hydrogen sites are favored compared with those on the alkyl side chains. The activation of methane is also observed in the DRIFT spectra when deuterium enriched methane is engaged as the methane source and evidenced by the escalated exothermic feature when olefin aromatization takes place under methane environment. The excellent catalytic performance of Ag-Ga/ZSM-5 might be because of the better dispersion of Ag and Ga on the ZSM-5 surface and moderate amount of strong Brosted and Lewis surface acid sites. All the observations suggest that methane might be activated nonoxidatively and converted into aromatics if suitable catalyst is charged under the assistance of co-existing olefin. In conclusion, the reported synergetic effect could potentially lead to the more economic utilization of abundant natural gas and petrochemical intermediates.« less

A novel nitro-oxy substituted analogue of rofecoxib reduces human colon cancer cell growth.

PubMed

Bocca, Claudia; Bozzo, Francesca; Ievolella, Monica; Miglietta, Antonella

2012-02-01

Rofecoxib is a specific COX-2 inhibitor able to exert antiproliferative activity against colorectal cancer cells. It was withdrawn from the market after the demonstration of an increased risk of cardiovascular complications after prolonged use. Nevertheless, it remains an interesting compound for laboratory research as an experimental COX-2 inhibitor. In this study, the antiproliferative activity of a novel dinitro-oxy-substituted analogue of rofecoxib (NO-rofe), potentially less cardiotoxic, has been investigated in vitro on human colon cancer cells and compared with the action of the parent drug. Due to the fact that COX-2 inhibition is the main characteristic of coxibs, we performed all experiments in COX-2-overexpressing (HT-29) and COX-2-negative (SW-480) human colon cancer cells, to elucidate whether the observed effects were dependent on COX-2 inhibition. Moreover, experiments were performed in order to evaluate whether COX-2 pharmacological inhibition may affect beta-catenin/E-cadherin signaling pathway. NO-rofe exerted a significant antiproliferative activity on COX-2 positive HT-29 human colon cancer cells, being less effective on the COX-2 negative SW-480 human colon cancer cell line. In particular, the rofecoxib analogue retained similar potencies with respect to COX-2 inhibition but was much more active than rofecoxib in inhibiting the growth of human colon cancer cells in vitro. In addition, this novel compound resulted in the induction of membrane β-catenin/E-cadherin expression, a feature that may significantly contribute to its antiproliferative activity.

Presence and potential significance of aromatic-ketone groups in aquatic humic substances

USGS Publications Warehouse

Leenheer, J.A.; Wilson, M.A.; Malcolm, R.L.

1987-01-01

Aquatic humic- and fulvic-acid standards of the International Humic Substances Society were characterized, with emphasis on carbonyl-group nature and content, by carbon-13 nuclear-magnetic-resonance spectroscopy, proton nuclear-magnetic-resonance spectroscopy, and infrared spectroscopy. After comparing spectral results of underivatized humic and fulvic acids with spectral results of chemically modified derivatives, that allow improved observation of the carbonyl group, the data clearly indicated that aromatic ketone groups comprised the majority of the carbonyl-group content. About one ketone group per monocyclic aromatic ring was determined for both humic and fulvic acids. Aromatic-ketone groups were hypothesized to form by photolytic rearrangements and oxidation of phenolic ester and hydrocarbon precursors; these groups have potential significance regarding haloform formation in water, reactivity resulting from active hydrogen of the methyl and methylene adjacent to the ketone groups, and formation of hemiketal and lactol structures. Aromatic-ketone groups also may be the point of attachment between aliphatic and aromatic moieties of aquatic humic-substance structure. ?? 1987.

Essential oil composition of stems and fruits of Caralluma europaea N.E.Br. (Apocynaceae).

PubMed

Zito, Pietro; Sajeva, Maurizio; Bruno, Maurizio; Maggio, Antonella; Rosselli, Sergio; Formisano, Carmen; Senatore, Felice

2010-01-27

The essential oil of the stems and fruits of Caralluma europaea (Guss.) N.E.Br. (Apocynaceae) from Lampedusa Island has been obtained by hydrodistillation and its composition analyzed. The analyses allowed the identification and quantification of 74 volatile compounds, of which 16 were aromatic and 58 non-aromatic. Stems and fruits contained 1.4% and 2.7% of aromatic compounds respectively, while non-aromatic were 88.3% and 88.8%. Non-aromatic hydrocarbons were the most abundant compounds in both organs, followed by fatty acids. Data showed differences in the profiles between stems and fruits which shared only eighteen compounds; stems accounted for 38 compounds while fruits for 53. Fruits showed a higher diversity especially in aromatic compounds with twelve versus four in stems. Among the volatiles identified in stems and fruits of C. europaea 26 are present in other taxa of Apocynaceae, 52 are semiochemicals for many insects, and 21 have antimicrobial activity. The possible ecological role of the volatiles found is briefly discussed.

Occurrences and behaviors of naphthenic acids in a petroleum refinery wastewater treatment plant.

PubMed

Wang, Beili; Wan, Yi; Gao, Yingxin; Zheng, Guomao; Yang, Min; Wu, Song; Hu, Jianying

2015-05-05

Naphthenic acids (NAs) are one class of compounds in wastewaters from petroleum industries that are known to cause toxic effects, and their removal from oilfield wastewater is an important challenge for remediation of large volumes of petrochemical effluents. The present study investigated occurrences and behaviors of total NAs and aromatic NAs in a refinery wastewater treatment plant, located in north China, which combined physicochemical and biological processes. Concentrations of total NAs were semiquantified to be 113-392 μg/L in wastewater from all the treatment units, and the percentages of aromatic NAs in total NAs was estimated to be 2.1-8.8%. The mass reduction for total NAs and aromatic NAs was 15±16% and 7.5±24% after the physicochemical treatment, respectively. Great mass reduction (total NAs: 65±11%, aromatic NAs: 86±5%) was observed in the biological treatment units, and antiestrogenic activities observed in wastewater from physicochemical treatment units disappeared in the effluent of the activated sludge system. The distributions of mass fractions of NAs demonstrated that biodegradation via activated sludge was the major mechanism for removing alicyclic NAs, aromatic NAs, and related toxicities in the plant, and the polycyclic NA congener classes were relatively recalcitrant to biodegradation, which is a complete contrast to the preferential adsorption of NAs with higher cyclicity (low Z value). Removal efficiencies of total NAs were 73±17% in summer, which were higher than those in winter (53±15%), and the seasonal variation was possibly due to the relatively high microbial biotransformation activities in the activated sludge system in summer (indexed by O3-NAs/NAs). The results of the investigations indicated that biotransformation of NA mixtures by the activated sludge system were largely affected by temperature, and employing an efficient adsorbent together with biodegradation processes would help cost-effectively remove NAs in petroleum effluents.

Polyphenylquinoxalines Via Aromatic Nucleophilic Displacement

NASA Technical Reports Server (NTRS)

Hergenrother, Paul M.; Connell, John W.

1991-01-01

Process for synthesis of polyphenylquinoxalines (PPQ's) involves nucleophilic displacement reactions of di(hydroxyphenyl) quinoxaline monomers with activated aromatic dihalides. New process costs less than other processes for synthesis of PPQ's. Facilitates synthesis of PPQ's of new and varied molecular structures. Useful as adhesives, coatings, films, membranes, and matrices for composites.

[The effect of sensory stimuli of varying modality on the human body functioning and indices of tense muscular activity].

PubMed

Kaĭdalin, V S; Kamchatnikov, A G; Sentiabrev, N N; Katuntsev, V P

2007-01-01

The work had a purpose to study benefits of aromatic blends of tonic and relaxing essences and functional music on some of the psychophysiological properties of the human functional state and motor activeity. Participants were 30 sprinters (18-22 y.o. males) having the first-class and master ranks. The psychophysiological indices of the athletes' functional state were evaluated with the use of the "CAH" and Spilberger situational anxiety tests, calculated Cardeu vegetative index, time for simple motor reaction and reaction to a moving object. Motor activity was evaluated by top running speed determined with a photo-electronic time-keeper and by duration of pedaling on bicycle ergometer at maximal power. The running step parameters were recorded with electropodography. It was shown that the positive effect of the aromatic essence blends and functional music on motor activity developed fairly rapidly but did not last long. The article discusses features and possible ways the aromatic blends and music effect human organism.

Screening of some Greek aromatic plants for antioxidant activity.

PubMed

Couladis, Maria; Tzakou, Olga; Verykokidou, Evmorfia; Harvala, Catherine

2003-02-01

The role of antioxidants in preventing oxygen radical and hydrogen peroxide induced cytotoxicity and tissue damage in various human diseases is increasingly recognized. In this study the in vitro antioxidant activity of the ethanol extracts obtained from 21 aromatic plants belonging to the Lamiaceae family was investigated. Of the extracts tested, those of Salvia ringens, Salvia pomifera, Stachys spruneri, Origanum dictamnus, Phlomis lanata, Ballota pseudodictamnus, Ballota acetabulosa, Teucrium polium, Calamintha glandulosa and Micromeria graeca exhibited the same activity as alpha-tocopherol. Copyright 2003 John Wiley & Sons, Ltd.

Enhancing muconic acid production from glucose and lignin-derived aromatic compounds via increased protocatechuate decarboxylase activity

DOE PAGES

Johnson, Christopher W.; Salvachua, Davinia; Khanna, Payal; ...

2016-04-22

The conversion of biomass-derived sugars and aromatic molecules to cis,cis-muconic acid (referred to hereafter as muconic acid or muconate) has been of recent interest owing to its facile conversion to adipic acid, an important commodity chemical. Metabolic routes to produce muconate from both sugars and many lignin-derived aromatic compounds require the use of a decarboxylase to convert protocatechuate (PCA, 3,4-dihydroxybenzoate) to catechol (1,2-dihydroxybenzene), two central aromatic intermediates in this pathway. Several studies have identified the PCA decarboxylase as a metabolic bottleneck, causing an accumulation of PCA that subsequently reduces muconate production. A recent study showed that activity of the PCAmore » decarboxylase is enhanced by co-expression of two genetically associated proteins, one of which likely produces a flavin-derived cofactor utilized by the decarboxylase. Using entirely genome-integrated gene expression, we have engineered Pseudomonas putida KT2440-derived strains to produce muconate from either aromatic molecules or sugars and demonstrate in both cases that co-expression of these decarboxylase associated proteins reduces PCA accumulation and enhances muconate production relative to strains expressing the PCA decarboxylase alone. In bioreactor experiments, co-expression increased the specific productivity (mg/g cells/h) of muconate from the aromatic lignin monomer p-coumarate by 50% and resulted in a titer of >15 g/L. In strains engineered to produce muconate from glucose, co-expression more than tripled the titer, yield, productivity, and specific productivity, with the best strain producing 4.92+/-0.48 g/L muconate. Furthermore, this study demonstrates that overcoming the PCA decarboxylase bottleneck can increase muconate yields from biomass-derived sugars and aromatic molecules in industrially relevant strains and cultivation conditions.« less

Designing of a fluoride selective receptor through molecular orbital engineering

NASA Astrophysics Data System (ADS)

Mishra, Rakesh K.; Kumar, Virendra; Diwan, Uzra; Upadhyay, K. K.; Roy Chowdhury, P. K.

2012-11-01

The stepwise substitution of appropriate groups over the 3-[(2,4-dinitro-phenyl)-hydrazono]-butyric acid ethyl ester (R3) lead receptor R1 which showed selectivity towards fluoride in DMSO. The UV-vis and 1H NMR titration studies revealed the details of the binding between receptor R1 and fluoride. The receptor R1 also recognized fluoride in a toothpaste solution to as low as 50 ppm. The theoretical simulations of recognition event at Density Functional Theory (DFT) level using B3LYP/6-31G** basis set and polarizable continuum model (PCM) approach lead a semi-quantitative match with the experimental results.

Problem Definition Study on TAX (1-acetylhexahydro-3,5-dinitro-1,3,5- triazine), SEX (1-acetyloctahydro-3,5,7-trinitro-1,3,5,7-tetrazocine), Lead Salicylate and Lead Beta-Resorcylate 2-Nitrodiphenylamine and Ethyl Centralite

DTIC Science & Technology

1979-07-01

4 -Nitroaniline to Fish .............................. ... V-30 , V-7. Toxicity of Potential Ethyl Centralite Degradation Products and Related...disappearance of 1 4 C-RDX was found in aerobically incubated cultures. Sikka et al. (1978) studied the microbial degradation of RDX. Water collected...00 A4 0 AA AOA to0 QT N N 14.4 P4 04.) tAO 0 0M k C 4.4 fA t 11- 4 b. BioaccumulatiOn and Degradation No nfortmatio• as found on the

Surface Acoustic Wave Devices as Chemical Vapor Sensors

DTIC Science & Technology

2009-03-26

x105cm/s) (x10−6cm1/2g1/2) (pF/cm) (ppm/oC) Quartz ST 3.158 0.13 1.34 0.88 0.0011 0.5 ∼ 0 X Lithium Niobate -Y 3.488 0 0.83 0.56 0.048 4.6 94 X Gallium ...sensitivity, followed by lithium niobate and gallium arsenide in ratios of 7.4:5.9:4.8, re- spectively. Thus, even though lithium niobate has the superior...Acoustic Wave (SAW) Sensor for 2,4-Dinitro Toluene (DNT) Vapour Detection,” Sensors and Actuators B: Chemical, vol. 101, no. 3, pp. 328–334, 2004. 8

From Biomass-Derived Furans to Aromatics with Ethanol over Zeolite.

PubMed

Teixeira, Ivo F; Lo, Benedict T W; Kostetskyy, Pavlo; Stamatakis, Michail; Ye, Lin; Tang, Chiu C; Mpourmpakis, Giannis; Tsang, Shik Chi Edman

2016-10-10

We report a novel catalytic conversion of biomass-derived furans and alcohols to aromatics over zeolite catalysts. Aromatics are formed via Diels-Alder cycloaddition with ethylene, which is produced in situ from ethanol dehydration. The use of liquid ethanol instead of gaseous ethylene, as the source of dienophile in this one-pot synthesis, makes the aromatics production much simpler and renewable, circumventing the use of ethylene at high pressure. More importantly, both our experiments and theoretical studies demonstrate that the use of ethanol instead of ethylene, results in significantly higher rates and higher selectivity to aromatics, due to lower activation barriers over the solid acid sites. Synchrotron-diffraction experiments and proton-affinity calculations clearly suggest that a preferred protonation of ethanol over the furan is a key step facilitating the Diels-Alder and dehydration reactions in the acid sites of the zeolite. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Airborne Exposures to Polycyclic Aromatic Compounds Among Workers in Asphalt Roofing Manufacturing Facilities.

PubMed

Trumbore, David C; Osborn, Linda V; Johnson, Kathleen A; Fayerweather, William E

2015-01-01

We studied exposure of 151 workers to polycyclic aromatic compounds and asphalt emissions during the manufacturing of asphalt roofing products-including 64 workers from 10 asphalt plants producing oxidized, straight-run, cutback, and wax- or polymer-modified asphalts, and 87 workers from 11 roofing plants producing asphalt shingles and granulated roll roofing. The facilities were located throughout the United States and used asphalt from many refiners and crude oils. This article helps fill a gap in exposure data for asphalt roofing manufacturing workers by using a fluorescence technique that targets biologically active 4-6 ring polycyclic aromatic compounds and is strongly correlated with carcinogenic activity in animal studies. Worker exposures to polycyclic aromatic compounds were compared between manufacturing plants, at different temperatures and using different raw materials, and to important external benchmarks. High levels of fine limestone particulate in the plant air during roofing manufacturing increased polycyclic aromatic compound exposure, resulting in the hypothesis that the particulate brought adsorbed polycyclic aromatic compounds to the worker breathing zone. Elevated asphalt temperatures increased exposures during the pouring of asphalt. Co-exposures in these workplaces which act as confounders for both the measurement of total organic matter and fluorescence were detected and their influence discussed. Exposures to polycyclic aromatic compounds in asphalt roofing manufacturing facilities were lower than or similar to those reported in hot-mix paving application studies, and much below those reported in studies of hot application of built-up roofing asphalt. These relatively low exposures in manufacturing are primarily attributed to air emission controls in the facilities, and the relatively moderate temperatures, compared to built-up roofing, used in these facilities for oxidized asphalt. The exposure to polycyclic aromatic compounds was a very small part of the overall worker exposure to asphalt fume, on average less than 0.07% of the benzene-soluble fraction. Measurements of benzene-soluble fraction were uniformly below the American Conference of Governmental Industrial Hygienists' Threshold Limit Value for asphalt fume.

De Novo Genome Project for the Aromatic Degrader Rhodococcus pyridinivorans Strain AK37

PubMed Central

Kriszt, Balázs; Táncsics, András; Cserháti, Mátyás; Tóth, Ákos; Nagy, István; Horváth, Balázs; Nagy, István; Tamura, Tomohiro; Szoboszlay, Sándor

2012-01-01

Here, we present the complete genome sequence of Rhodococcus pyridinivorans AK37 strain NCAIM PB1376, which was isolated from an oil-polluted site in Hungary. R. pyridinivorans AK37 is an aerobic, nonsporulating, nonmotile, Gram-positive bacterium with remarkable aromatic-decomposing activity. PMID:22328750

Discovering Chemical Aromaticity Using Fragrant Plants

ERIC Educational Resources Information Center

Schneider, Tanya L.

2010-01-01

Introductory organic chemistry is often perceived as inaccessible by students. This article describes a method used to link organic chemistry to everyday experience, asking students to explore whether fragrant molecules are also aromatic in the chemical sense. Students were engaged in this activity, excited about their results, and performed well…

SOLAR RADIATION DOSE AND PHOTOTOXICITY OF POLYCYCLIC AROMATIC HYDROCARBONS: A CASE STUDY

EPA Science Inventory

The toxicity of polycyclic aromatic hydrocarbons increases by as much as three orders of magnitude in the presence of solar radiation. The risk of this photoactive toxicity is thus based on both tissue concentrations of potentially photo activated compounds and the levels of subs...

TRENDS OF POLYCYCLIC AROMATIC HYDROCARBON LEVELS AND MUTAGENICITY IN SANTIAGO'S INHALABLE AIRBORNE PARTICLES IN THE PERIOD 1992-1996.

EPA Science Inventory

Abstract

Trends of polycyclic aromatic hydrocarbons (PAHs) for 1992-1996 (cold season) and their mutagenic activity were investigated in organic extracts from the Santiago. Chile. inhalable particles (PM10). The highest PAH concentrations were observed in 1992 and decline...

Experimental Determination of Activation Energy of Nucleophilic Aromatic Substitution on Porphyrins

ERIC Educational Resources Information Center

Rizvi, Waqar; Khwaja, Emaad; Siddiqui, Saim; Bhupathiraju, N. V. S. Dinesh K.; Drain, Charles Michael

2018-01-01

A physical organic chemistry experiment is described for second-year college students. Students performed nucleophilic aromatic substitution (NAS) reactions on 5,10,15,20-tetrakis(2,3,4,5,6-pentafluorophenyl)porphyrin (TPPF[subscript 20]) using three different nucleophiles. Substitution occurs preferentially at the 4-position ("para")…

Antifungal and repellent activities of the essential oils from three aromatic herbs from western Himalaya

USDA-ARS?s Scientific Manuscript database

In this investigation we examined the essential oils of three aromatic plants; Zanthoxylum armatum, Juniperus communis, and, Dysphania ambrosioides, which are used by the local population of the western Himalayan region for medicinal purposes. These plants were studied for their antifungal, larvicid...

Triazole nucleoside derivatives bearing aryl functionalities on the nucleobases show antiviral and anticancer activity.

PubMed

Xia, Yi; Qu, Fanqi; Peng, Ling

2010-08-01

Synthetic nucleoside mimics are important candidates in the searing for antiviral and anticancer drugs. Ribavirin, the first antiviral nucleoside drug, is unique in its antiviral activity with mutilple modes of action, which are mainly due to its special triazole heterocycle as nucleobase. Additionally, introducing aromatic functionalities to the nucleobase is able to confer novel mechanisms of action for nucleoside mimics. With the aim to combine the special characteristics of unnatural triazole heterocycles with those of the appended aromatic groups on the nucleobases, novel 1,2,4-triazole nucleoside analogs bearing aromatic moieties were designed and developed. The present short review summarizes the molecular design, chemical synthesis and biological activity of these triazole nucleoside analogs. Indeed, the discovery of antiviral and anticancer activities shown by these triazole nucleosides as well as the new mechanism underlying the biological activity by one of the anticancer leads has validated the rationale for molecular design and impacted us to further explore the concept with the aim of developing structurally novel nucleoside drug candidates with new modes of action.

Enhanced transformation of tetrabromobisphenol a by nitrifiers in nitrifying activated sludge.

PubMed

Li, Fangjie; Jiang, Bingqi; Nastold, Peter; Kolvenbach, Boris Alexander; Chen, Jianqiu; Wang, Lianhong; Guo, Hongyan; Corvini, Philippe François-Xavier; Ji, Rong

2015-04-07

The fate of the most commonly used brominated flame retardant, tetrabromobisphenol A (TBBPA), in wastewater treatment plants is obscure. Using a (14)C-tracer, we studied TBBPA transformation in nitrifying activated sludge (NAS). During the 31-day incubation, TBBPA transformation (half-life 10.3 days) was accompanied by mineralization (17% of initial TBBPA). Twelve metabolites, including those with single benzene ring, O-methyl TBBPA ether, and nitro compounds, were identified. When allylthiourea was added to the sludge to completely inhibit nitrification, TBBPA transformation was significantly reduced (half-life 28.9 days), formation of the polar and single-ring metabolites stopped, but O-methylation was not significantly affected. Abiotic experiments confirmed the generation of mono- and dinitro-brominated forms of bisphenol A in NAS by the abiotic nitration of TBBPA by nitrite, a product of ammonia-oxidizing microorganisms (AOMs). Three biotic (type II ipso-substitution, oxidative skeletal cleavage, and O-methylation) and one abiotic (nitro-debromination) pathways were proposed for TBBPA transformation in NAS. Apart from O-methylation, AOMs were involved in three other pathways. Our results are the first to provide information about the complex metabolism of TBBPA in NAS, and they are consistent with a determining role for nitrifiers in TBBPA degradation by initiating its cleavage into single-ring metabolites that are substrates for the growth of heterotrophic bacteria.

Heterolytic Activation of Hydrogen Promoted by Ruthenium Nanoparticles immobilized on Basic Supports and Hydrogenation of Aromatic Compounds

NASA Astrophysics Data System (ADS)

Fang, Minfeng

Despite the aggressive development and deployment of new renewable and nuclear technologies, petroleum-derived transportation fuels---gasoline, diesel and jet fuels---will continue to dominate the markets for decades. Environmental legislation imposes severe limits on the tolerable proportion of aromatics, sulfur and nitrogen contents in transportation fuels, which is difficult to achieve with current refining technologies. Catalytic hydrogenation plays an important role in the production of cleaner fuels, both as a direct means to reduce the aromatics and as a key step in the hydrodenitrogenation (HDN) and hydrodesulfurization (HDS) processes. However, conventional catalysts require drastic conditions and/or are easily poisoned by S or N aromatics. Therefore, there is still a need for new efficient catalysts for hydrogenation reactions relevant to the production of cleaner fossil fuels. Our catalyst design involves metallic nanoparticles intimately associated with a basic support, with the aim of creating a nanostructure capable of promoting the heterolytic activation of hydrogen and ionic hydrogenation mechanisms, as a strategy to avoid catalyst poisoning and enhance catalytic activity. We have designed and prepared a new nanostructured catalytic material composed of RuNPs immobilized on the basic polymer P4VPy. We have demonstrated that the Ru/P4VPy catalyst can promote heterolytic hydrogen activation and a unique surface ionic hydrogenation mechanism for the efficient hydrogenation of N-aromatics. This is the first time these ionic hydrogenation pathways have been demonstrated on solid surfaces. For the RuNPs surfaces without basic sites in close proximity, the conventional homolytic H2 splitting is otherwise involved. Using the mechanistic concepts from Ru/P4VPy, we have designed and prepared the Ru/MgO catalyst, with the aim to improve the catalytic efficiency for the hydrogenation of heteroatom aromatics operating by the ionic hydrogenation mechanism. The Ru/MgO catalyst significantly improves the catalytic efficiency for hydrogenation of a variety of N-/S-heteroaromatics and mono-/polycyclic aromatic hydrocarbons representative of components of petroleum-derived fuels. The catalyst is superior to the few other known supported noble metal catalysts for these reactions. Mechanistic studies also point to the ionic hydrogenation mechanism on the Ru/MgO surfaces. In addition, the Ru/MgO catalyst is highly recyclable and long-lived.

Polyphenylquinoxalines via Aromatic Nucleophilic Displacement

NASA Technical Reports Server (NTRS)

Hergenrother, Paul M.; Connell, John W.

1988-01-01

Polyphenylquinoxalines are produced by an aromatic nucleophilic displacement reaction involving an activated aromatic dihalide with an appropriate quinoxaline monomer. Polyphenylquinoxalines are high temperature thermoplastics used as adhesives, coatings, films and composite matrices. The novelty of this invention is threefold: (1) some of the quinoxaline monomers are new compositions of matter; (2) the phenylquinoxaline polymers which are the end products of the invention are new compositions of matter; and (3) the method of forming the polymers is novel, replacing a more costly prior art process, which is also limited in the kinds of products prepared therefrom.

Catalytic oxidation of o-aminophenols and aromatic amines by mushroom tyrosinase.

PubMed

Muñoz-Muñoz, Jose Luis; Garcia-Molina, Francisco; Garcia-Ruiz, Pedro Antonio; Varon, Ramon; Tudela, Jose; Rodriguez-Lopez, Jose N; Garcia-Canovas, Francisco

2011-12-01

The kinetics of tyrosinase acting on o-aminophenols and aromatic amines as substrates was studied. The catalytic constants of aromatic monoamines and o-diamines were both low, these results are consistent with our previous mechanism in which the slow step is the transfer of a proton by a hydroxyl to the peroxide in oxy-tyrosinase (Fenoll et al., Biochem. J. 380 (2004) 643-650). In the case of o-aminophenols, the hydroxyl group indirectly cooperates in the transfer of the proton and consequently the catalytic constants in the action of tyrosinase on these compounds are higher. In the case of aromatic monoamines, the Michaelis constants are of the same order of magnitude than for monophenols, which suggests that the monophenols bind better (higher binding constant) to the enzyme to facilitate the π-π interactions between the aromatic ring and a possible histidine of the active site. In the case of aromatic o-diamines, both the catalytic and Michaelis constants are low, the values of the catalytic constants being lower than those of the corresponding o-diphenols. The values of the Michaelis constants of the aromatic o-diamines are slightly lower than those of their corresponding o-diphenols, confirming that the aromatic o-diamines bind less well (lower binding constant) to the enzyme. Copyright © 2011 Elsevier B.V. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yung, Matthew M.; Stanton, Alexander R.; Iisa, Kristiina

Metal-impregnated (Ni or Ga) ZSM-5 catalysts were studied for biomass pyrolysis vapor upgrading to produce hydrocarbons using three reactors constituting a 100 000x change in the amount of catalyst used in experiments. Catalysts were screened for pyrolysis vapor phase upgrading activity in two small-scale reactors: (i) a Pyroprobe with a 10 mg catalyst in a fixed bed and (ii) a fixed-bed reactor with 500 mg of catalyst. The best performing catalysts were then validated with a larger scale fluidized-bed reactor (using ~1 kg of catalyst) that produced measurable quantities of bio-oil for analysis and evaluation of mass balances. Despite somemore » inherent differences across the reactor systems (such as residence time, reactor type, analytical techniques, mode of catalyst and biomass feed) there was good agreement of reaction results for production of aromatic hydrocarbons, light gases, and coke deposition. Relative to ZSM-5, Ni or Ga addition to ZSM-5 increased production of fully deoxygenated aromatic hydrocarbons and light gases. In the fluidized bed reactor, Ga/ZSM-5 slightly enhanced carbon efficiency to condensed oil, which includes oxygenates in addition to aromatic hydrocarbons, and reduced oil oxygen content compared to ZSM-5. Ni/ZSM-5, while giving the highest yield of fully deoxygenated aromatic hydrocarbons, gave lower overall carbon efficiency to oil but with the lowest oxygen content. Reaction product analysis coupled with fresh and spent catalyst characterization indicated that the improved performance of Ni/ZSM-5 is related to decreasing deactivation by coking, which keeps the active acid sites accessible for the deoxygenation and aromatization reactions that produce fully deoxygenated aromatic hydrocarbons. The addition of Ga enhances the dehydrogenation activity of the catalyst, which leads to enhanced olefin formation and higher fully deoxygenated aromatic hydrocarbon yields compared to unmodified ZSM-5. Catalyst characterization by ammonia temperature programmed desorption, surface area measurements, and postreaction temperature-programmed oxidation (TPO) also showed that the metal-modified zeolites retained a greater percentage of their initial acidity and surface area, which was consistent between the reactor scales. These results demonstrate that the trends observed with smaller (milligram to gram) catalyst reactors are applicable to larger, more industrially relevant (kg) scales to help guide catalyst research toward application.« less

Mutagenicity of an aged gasworks soil during bioslurry treatment

PubMed Central

Lemieux, Christine L; Lynes, Krista D; White, Paul A; Lundstedt, Staffan; Öberg, Lars; Lambert, Iain B

2009-01-01

This study investigated changes in the mutagenic activity of organic fractions from soil contaminated with polycyclic aromatic hydrocarbons (PAHs) during pilot-scale bioslurry remediation. Slurry samples were previously analyzed for changes in PAH and polycyclic aromatic compound content, and this study examined the correspondence between the chemical and toxicological metrics. Nonpolar neutral and semipolar aromatic fractions of samples obtained on days 0, 3, 7, 24, and 29 of treatment were assayed for mutagenicity using the Salmonella mutation assay. Most samples elicited a significant positive response on Salmonella strains TA98, YG1041, and YG1042 with and without S9 metabolic activation; however, TA100 failed to detect mutagenicity in any sample. Changes in the mutagenic activity of the fractions across treatment time and metabolic activation conditions suggests a pattern of formation and transformation of mutagenic compounds that may include a wide range of PAH derivatives such as aromatic amines, oxygenated PAHs, and S-heterocyclic compounds. The prior chemical analyses documented the formation of oxygenated PAHs during the treatment (e.g., 4-oxapyrene-5-one), and the mutagenicity analyses showed high corresponding activity in the semipolar fraction with and without metabolic activation. However, it could not be verified that these specific compounds were the underlying cause of the observed changes in mutagenic activity. The results highlight the need for concurrent chemical and toxicological profiling of contaminated sites undergoing remediation to ensure elimination of priority contaminants as well as a reduction in toxicological hazard. Moreover, the results imply that remediation efficacy and utility be evaluated using both chemical and toxicological metrics. Environ. Mol. Mutagen. 2009. © 2009 Wiley-Liss, Inc. PMID:19274766

REAL-TIME AND INTEGRATED MEASUREMENT OF POTENTIAL HUMAN EXPOSURE TO PARTICLE-BOUND POLYCYCLIC AROMATIC HYDROCARBONS (PAHS) FROM AIRCRAFT EXHAUST

EPA Science Inventory

Real-time monitors and low-volume air samplers were used to measure the potential human exposure to airborne polycyclic aromatic hydrocarbon (PAH) concentrations during various flight-related and ground-support activities of C-130H aircraft at an Air National Guard base. Three...

Polybenzimidazoles Via Aromatic Nucleophilic Displacement

NASA Technical Reports Server (NTRS)

Connell, John W.; Hergenrother, Paul M.; Smith, Joseph G.

1994-01-01

Soluble polybenzimidazoles (PBI's) synthesized by nucleophilic displacement reaction of di(hydroxyphenyl)-benzimidazole monomers with activated aromatic difluoride compounds in presence of anhydrous potassium carbonate. These polymers exhibit good thermal, thermo-oxidative, and chemical stability, and high mechanical properties. Using benzimidazole monomers, more economical, and new PBI's processed more easily than commercial PBI, without loss of desirable physical properties.

RELATING DAILY SOLAR ULTRAVIOLET RADIATION DOSE IN SALT MARSH-ASSOCIATED ESTUARINE SYSTEMS TO LABORATORY ASSESSMENTS OF PHOTOACTIVATED POLYCYCLIC AROMATIC HYDROCARBON TOXICITY

EPA Science Inventory

Estuaries of the southeastern United States not only serve an important nursery function but also are common repositories of polycyclic aromatic hydrocarbons (PAHs) derived from upland activities. Thus, these habitats may be at risk for PAHphototoxicity. To better characterize ...

SEASONAL VARIATION OF THE PARTICLE SIZE DISTRIBUTION OF POLYCYCLIC AROMATIC HYDROCARBONS AND OF MAJOR AEROSOL SPECIES IN CLAREMONT, CALIFORNIA. (R827352C020)

EPA Science Inventory

As part of the Southern California Particle Center and Supersite (SCPCS) activities, we measured, during all seasons, particle size distributions of 12 priority pollutant polycyclic aromatic hydrocarbons (PAHs), concurrently with elemental carbon (EC), organic carbon (OC), sul...

WHY DOES 5-METHYL CHRYSENE INTERACT WITH DNA LIKE BOTH A PLANAR AND A NON-PLANAR POLYCYCLIC AROMATIC HYDROCARBON? QUANTUM MECHANICAL STUDIES

EPA Science Inventory

Polycyclic aromatic hydrocarbons are a large class of anthropogenic chemicals found in the environment. Some class members are potent animal carcinogens while other similar class members show little carcinogenic activity. When considering a series of in vitro studies of the int...

Influence of Cadmium and Mercury on Activities of Ligninolytic Enzymes and Degradation of Polycyclic Aromatic Hydrocarbons by Pleurotus ostreatus in Soil

PubMed Central

Baldrian, Petr; in der Wiesche, Carsten; Gabriel, Jiří; Nerud, František; Zadražil, František

2000-01-01

The white-rot fungus Pleurotus ostreatus was able to degrade the polycyclic aromatic hydrocarbons (PAHs) benzo[a]anthracene, chrysene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene, dibenzo[a,h]anthracene, and benzo[ghi]perylene in nonsterile soil both in the presence and in the absence of cadmium and mercury. During 15 weeks of incubation, recovery of individual compounds was 16 to 69% in soil without additional metal. While soil microflora contributed mostly to degradation of pyrene (82%) and benzo[a]anthracene (41%), the fungus enhanced the disappearance of less-soluble polycyclic aromatic compounds containing five or six aromatic rings. Although the heavy metals in the soil affected the activity of ligninolytic enzymes produced by the fungus (laccase and Mn-dependent peroxidase), no decrease in PAH degradation was found in soil containing Cd or Hg at 10 to 100 ppm. In the presence of cadmium at 500 ppm in soil, degradation of PAHs by soil microflora was not affected whereas the contribution of fungus was negligible, probably due to the absence of Mn-dependent peroxidase activity. In the presence of Hg at 50 to 100 ppm or Cd at 100 to 500 ppm, the extent of soil colonization by the fungus was limited. PMID:10831426

Substrate and Enzyme Specificity of the Kinetic Isotope Effects Associated with the Dioxygenation of Nitroaromatic Contaminants.

PubMed

Pati, Sarah G; Kohler, Hans-Peter E; Pabis, Anna; Paneth, Piotr; Parales, Rebecca E; Hofstetter, Thomas B

2016-07-05

Compound-specific isotope analysis (CSIA) is a promising approach for tracking biotransformation of organic pollutants, but isotope fractionation associated with aromatic oxygenations is only poorly understood. We investigated the dioxygenation of a series of nitroaromatic compounds to the corresponding catechols by two enzymes, namely, nitrobenzene and 2-nitrotoluene dioxygenase (NBDO and 2NTDO) to elucidate the enzyme- and substrate-specificity of C and H isotope fractionation. While the apparent (13)C- and (2)H-kinetic isotope effects of nitrobenzene, nitrotoluene isomers, 2,6-dinitrotoluene, and naphthalene dioxygenation by NBDO varied considerably, the correlation of C and H isotope fractionation revealed a common mechanism for nitrobenzene and nitrotoluenes. Similar observations were made for the dioxygenation of these substrates by 2NTDO. Evaluation of reaction kinetics, isotope effects, and commitment-to-catalysis based on experiment and theory showed that rates of dioxygenation are determined by the enzymatic O2 activation and aromatic C oxygenation. The contribution of enzymatic O2 activation to the reaction rate varies for different nitroaromatic substrates of NBDO and 2NTDO. Because aromatic dioxygenation by nonheme iron dioxygenases is frequently the initial step of biodegradation, O2 activation kinetics may also have been responsible for the minor isotope fractionation reported for the oxygenation of other aromatic contaminants.

Aromatic aldehydes at the active site of aldehyde oxidoreductase from Desulfovibrio gigas: reactivity and molecular details of the enzyme-substrate and enzyme-product interaction.

PubMed

Correia, Hugo D; Marangon, Jacopo; Brondino, Carlos D; Moura, Jose J G; Romão, Maria J; González, Pablo J; Santos-Silva, Teresa

2015-03-01

Desulfovibrio gigas aldehyde oxidoreductase (DgAOR) is a mononuclear molybdenum-containing enzyme from the xanthine oxidase (XO) family, a group of enzymes capable of catalyzing the oxidative hydroxylation of aldehydes and heterocyclic compounds. The kinetic studies reported in this work showed that DgAOR catalyzes the oxidative hydroxylation of aromatic aldehydes, but not heterocyclic compounds. NMR spectroscopy studies using (13)C-labeled benzaldehyde confirmed that DgAOR catalyzes the conversion of aldehydes to the respective carboxylic acids. Steady-state kinetics in solution showed that high concentrations of the aromatic aldehydes produce substrate inhibition and in the case of 3-phenyl propionaldehyde a suicide substrate behavior. Hydroxyl-substituted aromatic aldehydes present none of these behaviors but the kinetic parameters are largely affected by the position of the OH group. High-resolution crystallographic structures obtained from single crystals of active-DgAOR soaked with benzaldehyde showed that the side chains of Phe425 and Tyr535 are important for the stabilization of the substrate in the active site. On the other hand, the X-ray data of DgAOR soaked with trans-cinnamaldehyde showed a cinnamic acid molecule in the substrate channel. The X-ray data of DgAOR soaked with 3-phenyl propionaldehyde showed clearly how high substrate concentrations inactivate the enzyme by binding covalently at the surface of the enzyme and blocking the substrate channel. The different reactivity of DgAOR versus aldehyde oxidase and XO towards aromatic aldehydes and N-heterocyclic compounds is explained on the basis of the present kinetic and structural data.

Biodegradation of Aromatic Compounds by Escherichia coli

PubMed Central

Díaz, Eduardo; Ferrández, Abel; Prieto, María A.; García, José L.

2001-01-01

Although Escherichia coli has long been recognized as the best-understood living organism, little was known about its abilities to use aromatic compounds as sole carbon and energy sources. This review gives an extensive overview of the current knowledge of the catabolism of aromatic compounds by E. coli. After giving a general overview of the aromatic compounds that E. coli strains encounter and mineralize in the different habitats that they colonize, we provide an up-to-date status report on the genes and proteins involved in the catabolism of such compounds, namely, several aromatic acids (phenylacetic acid, 3- and 4-hydroxyphenylacetic acid, phenylpropionic acid, 3-hydroxyphenylpropionic acid, and 3-hydroxycinnamic acid) and amines (phenylethylamine, tyramine, and dopamine). Other enzymatic activities acting on aromatic compounds in E. coli are also reviewed and evaluated. The review also reflects the present impact of genomic research and how the analysis of the whole E. coli genome reveals novel aromatic catabolic functions. Moreover, evolutionary considerations derived from sequence comparisons between the aromatic catabolic clusters of E. coli and homologous clusters from an increasing number of bacteria are also discussed. The recent progress in the understanding of the fundamentals that govern the degradation of aromatic compounds in E. coli makes this bacterium a very useful model system to decipher biochemical, genetic, evolutionary, and ecological aspects of the catabolism of such compounds. In the last part of the review, we discuss strategies and concepts to metabolically engineer E. coli to suit specific needs for biodegradation and biotransformation of aromatics and we provide several examples based on selected studies. Finally, conclusions derived from this review may serve as a lead for future research and applications. PMID:11729263

Comparative study of n-hexane aromatization on Pt/KL, Pt/Mg(Al)O, and Pt/SiO{sub 2} catalysts: Clean and sulfur-containing feeds

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jacobs, G.; Padro, C.L.; Resasco, D.E.

The n-hexane aromatization has been studied on Pt/KL, Pt/Mg(Al)O, and Pt/SiO{sub 2} catalysts at 773 K using sulfur-free and 0.6 ppm sulfur containing feedstocks. Examination of the product distribution as a function of conversion suggests that the formation of benzene is preceded by the formation of hexenes. In contrast with previous reports, it has been found that the Pt/KL catalyst exhibits much higher aromatization activity than the Pt/Mg(Al)O catalyst. On Pt/KL the main product is benzene, with hexenes and lighter compounds as the principal by-products. By contrast, on the Pt/Mg(Al)O, the main products were hexenes. Since hexenes are primary productsmore » and benzene is a secondary product, the exceptional aromatization activity of Pt/KL is explained in terms of its ability to convert hexene into benzene. In the presence of sulfur, the Pt/KL exhibits a rapid loss in n-hexane conversion and benzene selectivity. Under these conditions, the sulfided Pt/KL catalyst presents a catalytic behavior typical of Pt/Mg(Al)O and Pt/SiO{sub 2}, generating larger amounts of hexenes. The observed results are consistent with the hypothesis that the most important role of the zeolite is to inhibit bimolecular interactions that lead to coke formation. The formation of coke has the net effect of selectively deactivating aromatization sites which require a large ensemble of atoms to constitute the active site but not affecting the dehydrogenation activity which is less ensemble-sensitive. Therefore, those particles that are not protected against coking inside the channels of the zeolite rapidly become unselective. In support of this hypothesis, the hydrogenolysis reaction which also requires a large ensemble of atoms, decreases in parallel with the aromatization reaction. The high sensitivity of Pt/KL to sulfur may be due to a combination of effects which may involve growth of metal particles outside the zeolite which would become unselective and partial poisoning of the particles inside the zeolite, causing a similar selective deactivation.« less

Synthesis and activity of novel analogs of hemiasterlin as inhibitors of tubulin polymerization: modification of the A segment.

PubMed

Yamashita, Ayako; Norton, Emily B; Kaplan, Joshua A; Niu, Chuan; Loganzo, Frank; Hernandez, Richard; Beyer, Carl F; Annable, Tami; Musto, Sylvia; Discafani, Carolyn; Zask, Arie; Ayral-Kaloustian, Semiramis

2004-11-01

Analogs of hemiasterlin (1) and HTI-286 (2), which contain various aromatic rings in the A segment, were synthesized as potential inhibitors of tubulin polymerization. The structure-activity relationships related to stereo- and regio-chemical effects of substituents on the aromatic ring in the A segment were studied. Analogs, which carry a meta-substituted phenyl ring in the A segment show comparable activity for inhibition of tubulin polymerization to 2, as well as in the cell proliferation assay using KB cells containing P-glycoprotein, compared to those of 1 and 2.

Dermal exposure to jet fuel suppresses delayed-type hypersensitivity: a critical role for aromatic hydrocarbons.

PubMed

Ramos, Gerardo; Limon-Flores, Alberto Yairh; Ullrich, Stephen E

2007-12-01

Dermal exposure to military (JP-8) and/or commercial (Jet-A) jet fuel suppresses cell-mediated immune reactions. Immune regulatory cytokines and biological modifiers, including platelet activating factor (PAF), prostaglandin E(2), and interleukin-10, have been implicated in the pathway of events leading to immune suppression. It is estimated that approximately 260 different hydrocarbons are found in jet fuel, and the exact identity of the active immunotoxic agent(s) is unknown. The recent availability of synthetic jet fuel (S-8), which is refined from natural gas, and is devoid of aromatic hydrocarbons, made it feasible to design experiments to address this problem. Here we tested the hypothesis that the aromatic hydrocarbons present in jet fuel are responsible for immune suppression. We report that applying S-8 to the skin of mice does not upregulate the expression of epidermal cyclooxygenase-2 (COX-2) nor does it induce immune suppression. Adding back a cocktail of seven of the most prevalent aromatic hydrocarbons found in jet fuel (benzene, toluene, ethylbenzene, xylene, 1,2,4-trimethlybenzene, cyclohexylbenzene, and dimethylnaphthalene) to S-8 upregulated epidermal COX-2 expression and suppressed a delayed-type hypersensitivity (DTH) reaction. Injecting PAF receptor antagonists, or a selective cycloozygenase-2 inhibitor into mice treated with S-8 supplemented with the aromatic cocktail, blocked suppression of DTH, similar to data previously reported using JP-8. These findings identify the aromatic hydrocarbons found in jet fuel as the agents responsible for suppressing DTH, in part by the upregulation of COX-2, and the production of immune regulatory factors and cytokines.

Multifunctional receptor model for dioxin and related compound toxic action: possible thyroid hormone-responsive effector-linked site.

PubMed Central

McKinney, J D

1989-01-01

Molecular/theoretical modeling studies have revealed that thyroid hormones and toxic chlorinated aromatic hydrocarbons of environmental significance (for which dioxin or TCDD is the prototype) have similar structural properties that could be important in molecular recognition in biochemical systems. These molecular properties include a somewhat rigid, sterically accessible and polarizable aromatic ring and size-limited, hydrophobic lateral substituents, usually contained in opposite adjoining rings of a diphenyl compound. These molecular properties define the primary binding groups thought to be important in molecular recognition of both types of structures in biochemical systems. Similar molecular reactivities are supported by the demonstration of effective specific binding of thyroid hormones and chlorinated aromatic hydrocarbons with four different proteins, enzymes, or receptor preparations that are known or suspected to be involved in the expression of thyroid hormone activity. These binding interactions represent both aromatic-aromatic (stacking) and molecular cleft-type recognition processes. A multiple protein or multifunctional receptor-ligand binding mechanism model is proposed as a way of visualizing the details and possible role of both the stacking and cleft type molecular recognition factors in the expression of biological activity. The model suggests a means by which hormone-responsive effector-linked sites (possible protein-protein-DNA complexes) can maintain highly structurally specific control of hormone action. Finally, the model also provides a theoretical basis for the design and conduct of further biological experimentation on the molecular mechanism(s) of action of toxic chlorinated aromatic hydrocarbons and thyroid hormones. Images FIGURE 3. A FIGURE 3. B FIGURE 3. C FIGURE 3. D PMID:2551666

Breaking Benzene Aromaticity-Computational Insights into the Mechanism of the Tungsten-Containing Benzoyl-CoA Reductase.

PubMed

Culka, Martin; Huwiler, Simona G; Boll, Matthias; Ullmann, G Matthias

2017-10-18

Aromatic compounds are environmental pollutants with toxic and carcinogenic properties. Despite the stability of aromatic rings, bacteria are able to degrade the aromatic compounds into simple metabolites and use them as growth substrates under oxic or even under anoxic conditions. In anaerobic microorganisms, most monocyclic aromatic growth substrates are converted to the central intermediate benzoyl-coenzyme A, which is enzymatically reduced to cyclohexa-1,5-dienoyl-CoA. The strictly anaerobic bacterium Geobacter metallireducens uses the class II benzoyl-CoA reductase complex for this reaction. The catalytic BamB subunit of this complex harbors an active site tungsten-bis-pyranopterin cofactor with the metal being coordinated by five protein/cofactor-derived sulfur atoms and a sixth, so far unknown, ligand. Although BamB has been biochemically and structurally characterized, its mechanism still remains elusive. Here we use continuum electrostatic and QM/MM calculations to model benzoyl-CoA reduction by BamB. We aim to elucidate the identity of the sixth ligand of the active-site tungsten ion together with the interplay of the electron and proton transfer events during the aromatic ring reduction. On the basis of our calculations, we propose that benzoyl-CoA reduction is initiated by a hydrogen atom transfer from a W(IV) species with an aqua ligand, yielding W(V)-[OH - ] and a substrate radical intermediate. In the next step, a proton-assisted second electron transfer takes place with a conserved active-site histidine serving as the second proton donor. Interestingly, our calculations suggest that the electron for the second reduction step is taken from the pyranopterin cofactors rather than from the tungsten ion. The resulting cationic radical, which is distributed over both pyranopterins, is stabilized by conserved anionic amino acid residues. The stepwise mechanism of the reduction shows similarities to the Birch reduction known from organic chemistry. However, the strict coupling of protons and electrons allows the reaction to proceed under milder conditions.

Comparative analysis of the electrostatic potentials of some structural analogues of 2,3,7,8-tetrachlorodibenzo-p-dioxin and of related aromatic systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Murray, J.S.; Evans, P.; Politzer, P.

1990-01-01

An ab initio STO-5G computational analysis of the electrostatic potentials of four structural analogs of the highly toxic 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and four related aromatic systems (benzo(a)pyrene, benz(a)anthracene and two isomeric benzoflavones) was carried out. The systems, to varying degrees, induce aryl hydrocarbon hydroxylase activity and are believed to interact with the same cytosolic receptor in initiating their biochemical responses. It was found that a high degree of activity appears to require negative potentials that are non-overlapping above all or most of the lateral regions, with an observed optimum range of magnitudes. In systems with central oxygens, it is required thatmore » the negative oxygen potentials be small and weak; however, oxygen negative regions in the molecule are not necessary for high activity. The observed differences between the potential patterns of the four aromatic systems and those of TCDD and its active analogs may reflect an inherent dissimilarity in the nature of their interactions with the cytosolic receptor.« less

Chemoenzymatic syntheses of prenylated aromatic small molecules using Streptomyces prenyltransferases with relaxed substrate specificities

PubMed Central

Kumano, Takuto; Richard, Stéphane B.; Noel, Joseph P.; Nishiyama, Makoto; Kuzuyama, Tomohisa

2010-01-01

NphB is a soluble prenyltransferase from Streptomyces sp. strain CL190 that attaches a geranyl group to a 1,3,6,8-tetrahydroxynaphthalene-derived polyketide during the biosynthesis of anti-oxidant naphterpin. Here we report multiple chemoenzymatic syntheses of various prenylated compounds from aromatic substrates including flavonoids using two prenyltransferases NphB and SCO7190, a NphB homolog from Streptomyces coelicolor A3(2), as biocatalysts. NphB catalyzes carbon–carbon-based and carbon–oxygen-based geranylation of a diverse collection of hydroxyl-containing aromatic acceptors. Thus, this simple method using the prenyltransferases can be used to explore novel prenylated aromatic compounds with biological activities. Kinetic studies with NphB reveal that the prenylation reaction follows a sequential ordered mechanism. PMID:18682327

Polycyclic aromatic hydrocarbon degradation by biosurfactant-producing Pseudomonas sp. IR1.

PubMed

Kumara, Manoj; Leon, Vladimir; De Sisto Materano, Angela; Ilzins, Olaf A; Galindo-Castro, Ivan; Fuenmayor, Sergio L

2006-01-01

We characterized a newly isolated bacterium, designated as IR1, with respect to its ability to degrade polycyclic aromatic hydrocarbons (PAHs) and to produce biosurfactants. Isolated IR1 was identified as Pseudomonas putida by analysis of 16S rRNA sequences (99.6% homology). It was capable of utilizing two-, three- and four-ring PAHs but not hexadecane and octadecane as a sole carbon and energy source. PCR and DNA hybridization studies showed that enzymes involved in PAH metabolism were related to the naphthalene dioxygenase pathway. Observation of both tensio-active and emulsifying activities indicated that biosurfactants were produced by IR1 during growth on both water miscible and immiscible substrates. The biosurfactants lowered the surface tension of medium from 54.9 dN cm(-1) to 35.4 dN cm(-1) and formed a stable and compact emulsion with an emulsifying activity of 74% with diesel oil, when grown on dextrose. These findings indicate that this isolate may be useful for bioremediation of sites contaminated with aromatic hydrocarbons.

Structure-Activity Relationships for Rates of Aromatic Amine Oxidation by Manganese Dioxide.

PubMed

Salter-Blanc, Alexandra J; Bylaska, Eric J; Lyon, Molly A; Ness, Stuart C; Tratnyek, Paul G

2016-05-17

New energetic compounds are designed to minimize their potential environmental impacts, which includes their transformation and the fate and effects of their transformation products. The nitro groups of energetic compounds are readily reduced to amines, and the resulting aromatic amines are subject to oxidation and coupling reactions. Manganese dioxide (MnO2) is a common environmental oxidant and model system for kinetic studies of aromatic amine oxidation. In this study, a training set of new and previously reported kinetic data for the oxidation of model and energetic-derived aromatic amines was assembled and subjected to correlation analysis against descriptor variables that ranged from general purpose [Hammett σ constants (σ(-)), pKas of the amines, and energies of the highest occupied molecular orbital (EHOMO)] to specific for the likely rate-limiting step [one-electron oxidation potentials (Eox)]. The selection of calculated descriptors (pKa, EHOMO, and Eox) was based on validation with experimental data. All of the correlations gave satisfactory quantitative structure-activity relationships (QSARs), but they improved with the specificity of the descriptor. The scope of correlation analysis was extended beyond MnO2 to include literature data on aromatic amine oxidation by other environmentally relevant oxidants (ozone, chlorine dioxide, and phosphate and carbonate radicals) by correlating relative rate constants (normalized to 4-chloroaniline) to EHOMO (calculated with a modest level of theory).

Adsorption of aromatic hydrocarbons and ozone at environmental aqueous surfaces.

PubMed

Vácha, Robert; Cwiklik, Lukasz; Rezác, Jan; Hobza, Pavel; Jungwirth, Pavel; Valsaraj, Kalliat; Bahr, Stephan; Kempter, Volker

2008-06-05

Adsorption of environmentally important aromatic molecules on a water surface is studied by means of classical and ab initio molecular dynamics simulations and by reflection-absorption infrared spectroscopy. Both techniques show strong activity and orientational preference of these molecules at the surface. Benzene and naphthalene, which bind weakly to water surface with a significant contribution of dispersion interactions, prefer to lie flat on water but retain a large degree of orientational flexibility. Pyridine is more rigid at the surface. It is tilted with the nitrogen end having strong hydrogen bonding interactions with water molecules. The degree of adsorption and orientation of aromatic molecules on aqueous droplets has atmospheric implications for heterogeneous ozonolysis, for which the Langmuir-Hinshelwood kinetics mechanism is discussed. At higher coverages of aromatic molecules the incoming ozone almost does not come into contact with the underlying aqueous phase. This may rationalize the experimental insensitivity of the ozonolysis on the chemical nature of the substrate on which the aromatic molecules adsorb.

Pseudomonads biodegradation of aromatic compounds in oil sands process-affected water.

PubMed

Zhang, Yanyan; McPhedran, Kerry N; Gamal El-Din, Mohamed

2015-07-15

Aromatic naphthenic acids (NAs) have been shown to be more toxic than the classical NAs found in oil sands process-affected water (OSPW). To reduce this toxicity, Pseudomonas fluorescens and Pseudomonas putida were used to determine their ability to biodegrade aromatic compounds including treatments considering the impacts of external carbon and iron addition. Results showed that with added carbon P. fluorescens and P. putida have the capability of biodegrading these aromatics. In the presence of external carbon, gene expression of a functional PAH-ring hydroxylating dioxygenase (PAH-RHDα) was determined through reverse transcription real-time PCR, suggesting active degradation of OSPW aromatic compounds. Although no significant classical NAs removal was observed during this process, toxicity was reduced by 49.3% under optimal conditions. OSPW toxicity was eliminated with the combination of ozonation at a dose of 80 mg/L followed by biodegradation, indicating that it is a promising combined OSPW treatment approach for the safe discharge to the aquatic environment. Copyright © 2015 Elsevier B.V. All rights reserved.

Dendrimer encapsulated Silver nanoparticles as novel catalysts for reduction of aromatic nitro compounds

NASA Astrophysics Data System (ADS)

Asharani, I. V.; Thirumalai, D.; Sivakumar, A.

2017-11-01

Polyethylene glycol (PEG) core dendrimer encapsulated silver nanoparticles (AgNPs) were synthesized through normal chemical reduction method, where dendrimer acts as reducing and stabilizing agent. The encapsulated AgNPs were well characterized using TEM, DLS and XPS techniques. The synthesized AgNPs showed excellent catalytic activity towards the reduction of aromatic nitro compounds with sodium borohydride as reducing agent and the results substantiate that dendrimer encapsulated AgNPs can be an effective catalyst for the substituted nitro aromatic reduction reactions. Also the kinetics of different nitro compounds reductions was studied and presented.

Dramatic Influence of Ionic Liquid and Ultrasound Irradiation on the Electrophilic Sulfinylation of Aromatic Compounds by Sulfinic Esters.

PubMed

Nguyen, Ngoc-Lan Thi; Vo, Hong-Thom; Duus, Fritz; Luu, Thi Xuan Thi

2017-09-04

The sulfinylation reaction of aromatic and hetero-aromatic compounds with sulfinic esters as electrophiles has been investigated in different ionic liquids and by means of different Lewis acid salts in order to get moderate to good yields of asymmetrical sulfoxides. Mixtures of 1-butyl-3-methylimidazolium chloride and aluminum chloride were found to be the most efficient and recyclable reaction framework. Ultrasound sonication appeared to be the most useful and green activation method to afford the sulfoxides in yields better than or equivalent to those obtained under the longer-lasting conventional stirring conditions.

Antimicrobial activity of essential oils from Mediterranean aromatic plants against several foodborne and spoilage bacteria.

PubMed

Silva, Nuno; Alves, Sofia; Gonçalves, Alexandre; Amaral, Joana S; Poeta, Patrícia

2013-12-01

The antimicrobial activity of essential oils extracted from a variety of aromatic plants, often used in the Portuguese gastronomy was studied in vitro by the agar diffusion method. The essential oils of thyme, oregano, rosemary, verbena, basil, peppermint, pennyroyal and mint were tested against Gram-positive (Listeria monocytogenes, Clostridium perfringens, Bacillus cereus, Staphylococcus aureus, Enterococcus faecium, Enterococcus faecalis, and Staphylococcus epidermidis) and Gram-negative strains (Salmonella enterica, Escherichia coli, and Pseudomonas aeruginosa). For most essential oils examined, S. aureus, was the most susceptible bacteria, while P. aeruginosa showed, in general, least susceptibility. Among the eight essential oils evaluated, thyme, oregano and pennyroyal oils showed the greatest antimicrobial activity, followed by rosemary, peppermint and verbena, while basil and mint showed the weakest antimicrobial activity. Most of the essential oils considered in this study exhibited a significant inhibitory effect. Thyme oil showed a promising inhibitory activity even at low concentration, thus revealing its potential as a natural preservative in food products against several causal agents of foodborne diseases and food spoilage. In general, the results demonstrate that, besides flavoring the food, the use of aromatic herbs in gastronomy can also contribute to a bacteriostatic effect against pathogens.

Diversity of organotrophic bacteria, activity of dehydrogenases and urease as well as seed germination and root growth Lepidium sativum, Sorghum saccharatum and Sinapis alba under the influence of polycyclic aromatic hydrocarbons.

PubMed

Lipińska, Aneta; Wyszkowska, Jadwiga; Kucharski, Jan

2015-12-01

Polycyclic aromatic hydrocarbons are organic compounds with highly toxic, carcinogenic, and mutagenic properties, which adversely affect the basic biological parameters of the soil, including the count of microorganisms, and the enzymatic activity. In addition to disturbances to the biological activity of the soil, PAHs may also exhibit toxic effects on plants. In view of the above, the study involved testing aimed at the determination of the effects of polycyclic aromatic hydrocarbons in a form of naphthalene, phenanthrene, anthracene and pyrene on the count, colony development (CD) index, ecophysiological (EP) diversity index of organotrophic bacteria, and the activity of soil dehydrogenases and soil urease. Moreover, an attempt was made to determine the soil's resistance based on the activity of the above-listed enzymes, and the effect of polycyclic aromatic hydrocarbons on seed germination and root growth was assessed by Lepidium sativum, Sorghum saccharatum, and Sinapis alba. In addition, the species of bacteria found in a soil subjected to strong pressure of polycyclic aromatic hydrocarbons were isolated. The experiment was performed in a laboratory on samples of loamy sand. Polycyclic aromatic hydrocarbons were introduced into the soil in an amount of 0, 1000, 2000, and 4000 mg kg(-1) of soil dry matter. Germination and growth of cress (L. sativum), white mustard (S. alba), and sweet sorghum (S. saccharatum) were determined using Phytotoxkit tests. It was found that the tested PAHs increased the average colony counts of organotrophic soil bacteria; pyrene did so to the greatest extent (2.2-fold relative to non-contaminated soil), phenanthrene to the smallest extent (1.4-fold relative to non-contaminated soil). None of the PAHs changed the value of the bacterial colony development (CD) index, while anthracene and pyrene increased the value of the eco-physiological (EP) diversity indicator. PAHs lowered the activity of the tested enzymes. The activity of dehydrogenases was dependent on a greater extent by the type of hydrocarbon (54.56%) rather than by the dose (10.64%), while for the activity of urease, it was the opposite. The greater extent was dependent on dose (95.42%) rather than by type (0.21%). Dehydrogenases are characterised by greater resistance to the action of PAHs than urease. Based on seed germination and root growth, it has shown that S. alba is best suited, being the most vulnerable plant, while S. saccharatum is the least suited. Subjecting a soil to strong pressure of PAHs leads to disturbances to the biological parameters of the soil, seed germination, and root growth L. sativum, S. saccharatum, and S. alba.

Involvement of substance P and central opioid receptors in morphine modulation of the CHS response.

PubMed

Nelson, C J; Lysle, D T

2001-04-02

Morphine administration prior to challenge with the antigen 2,4-dinitro-fluorobenzene increases the contact hypersensitivity (CHS) response in rats. The present study extended these findings by showing that central, but not systemic, administration of N-methylnaltrexone antagonized the morphine-induced enhancement of the CHS response. The importance of the neuroimmune mediator substance P was shown via the attenuation of the morphine-induced enhancement following both systemic and topical administration of the NK-1 antagonist WIN51,708. Taken together, the findings of the present study provide new data showing that central opioid receptors and peripheral substance P are involved in the morphine-induced enhancement of the CHS response.

Method for synthesizing N.sub.2 O.sub.5

DOEpatents

McGuire, Raymond R.; Coon, Clifford L.; Harrar, Jackson E.; Pearson, Richard K.

1985-01-01

A method and apparatus for electrochemically synthesizing N.sub.2 O.sub.5 includes oxidizing a solution of N.sub.2 O.sub.4 /HNO.sub.3 at an anode, while maintaining a controlled potential between the N.sub.2 O.sub.4 /HNO.sub.3 solution and the anode. A potential of about 1.35 to 2.0 V vs. SCE is preferred, while a potential of about 1.80 V vs. SCE is most preferred. Thereafter, the N.sub.2 O.sub.5 is reacted with either 1.5-diacetyl-3,7-dinitro-1,3,5,7-tetraazacyclooctane (DADN) or 1,3,5,7-tetraacetyl-1,3,5,7-tetraazacyclooctane (TAT) to form cyclotetramethylenetetraamine (HMX).

Method for synthesizing HMX

DOEpatents

McGuire, Raymond R.; Coon, Clifford L.; Harrar, Jackson E.; Pearson, Richard K.

1984-01-01

A method and apparatus for electrochemically synthesizing N.sub.2 O.sub.5 cludes oxidizing a solution of N.sub.2 O.sub.4 /HNO.sub.3 at an anode, while maintaining a controlled potential between the N.sub.2 O.sub.4 /HNO.sub.3 solution and the anode. A potential of about 1.35 to 2.0 V vs. SCE is preferred, while a potential of about 1.80 V vs. SCE is most preferred. Thereafter, the N.sub.2 O.sub.5 is reacted with either 1.5-diacetyl-3,7-dinitro-1,3,5,7-tetraazacyclooctane (DADN) or 1,3,5,7-tetraacetyl-1,3,5,7-tetraazacyclooctane (TAT) to form cyclotetramethylenetetraamine (HMX).

Catalytic co-aromatization of ethanol and methane

DOE PAGES

Wang, Aiguo; He, Peng; Yung, Matthew; ...

2016-06-06

This study demonstrates the technical feasibility of simultaneously converting ethanol and methane into liquid hydrocarbons at mild reaction conditions (400 °C and 1 atm) over silver and/or zinc modified zeolite catalysts. After GC-MS analysis, it is worth noting that aromatics are the major compounds contained in the liquid product collected from the run when 1%Ag/ZSM-5, particularly after H 2 pretreatment, is charged. Compared to the performance exhibited from the run with pure HZSM-5 support engaged, Ag addition into the HZSM-5 framework favors aromatics formation, which might be closely associated with better Ag dispersion and more abundance of strong surface acidicmore » sites where aromatization might take place while Zn loading exerts a detrimental effect on the production of aromatics but promotes the ether generation possibly through dehydration reaction. Referred to that from its N 2 counterpart, the increased aromatics formation of the collected liquid product when methane is present indicates that methane existence might facilitate ethanol aromatization. Moreover, combined with the increased carbon number in the formed aromatics from CH 4 run when H 2 run is referred and zero liquid formation from CH 4-alone test as well as more prominent endothermic feature of methane run and more importantly the notably increased 13C signals in 13C NMR spectra of the liquid product collected during ethanol conversion under 13CH 4 environment, all the observations suggest that methane might be activated nonoxidatively and converted into higher hydrocarbons, preferentially into aromatics if suitable catalyst is charged under the assistance of co-existing oxygenated hydrocarbon. Lastly, the reported synergetic effect could potentially lead to the more economic utilization of abundant natural gas and cellulosic ethanol.« less

Study of the antibacterial and antifungal activities of synthetic benzyl bromides, ketones, and corresponding chalcone derivatives.

PubMed

Shakhatreh, Muhamad Ali K; Al-Smadi, Mousa L; Khabour, Omar F; Shuaibu, Fatima A; Hussein, Emad I; Alzoubi, Karem H

2016-01-01

Several applications of chalcones and their derivatives encouraged researchers to increase their synthesis as an alternative for the treatment of pathogenic bacterial and fungal infections. In the present study, chalcone derivatives were synthesized through cross aldol condensation reaction between 4-( N , N -dimethylamino)benzaldehyde and multiarm aromatic ketones. The multiarm aromatic ketones were synthesized through nucleophilic substitution reaction between 4-hydroxy acetophenone and benzyl bromides. The benzyl bromides, multiarm aromatic ketones, and corresponding chalcone derivatives were evaluated for their activities against eleven clinical pathogenic Gram-positive, Gram-negative bacteria, and three pathogenic fungi by the disk diffusion method. The minimum inhibitory concentration was determined by the microbroth dilution technique. The results of the present study demonstrated that benzyl bromide derivatives have strong antibacterial and antifungal properties as compared to synthetic chalcone derivatives and ketones. Benzyl bromides (1a and 1c) showed high ester activity against Gram-positive bacteria and fungi but moderate activity against Gram-negative bacteria. Therefore, these compounds may be considered as good antibacterial and antifungal drug discovery. However, substituted ketones (2a-b) as well as chalcone derivatives (3a-c) showed no activity against all the tested strains except for ketone (2c), which showed moderate activity against Candida albicans .

Study of the antibacterial and antifungal activities of synthetic benzyl bromides, ketones, and corresponding chalcone derivatives

PubMed Central

Shakhatreh, Muhamad Ali K; Al-Smadi, Mousa L; Khabour, Omar F; Shuaibu, Fatima A; Hussein, Emad I; Alzoubi, Karem H

2016-01-01

Several applications of chalcones and their derivatives encouraged researchers to increase their synthesis as an alternative for the treatment of pathogenic bacterial and fungal infections. In the present study, chalcone derivatives were synthesized through cross aldol condensation reaction between 4-(N,N-dimethylamino)benzaldehyde and multiarm aromatic ketones. The multiarm aromatic ketones were synthesized through nucleophilic substitution reaction between 4-hydroxy acetophenone and benzyl bromides. The benzyl bromides, multiarm aromatic ketones, and corresponding chalcone derivatives were evaluated for their activities against eleven clinical pathogenic Gram-positive, Gram-negative bacteria, and three pathogenic fungi by the disk diffusion method. The minimum inhibitory concentration was determined by the microbroth dilution technique. The results of the present study demonstrated that benzyl bromide derivatives have strong antibacterial and antifungal properties as compared to synthetic chalcone derivatives and ketones. Benzyl bromides (1a and 1c) showed high ester activity against Gram-positive bacteria and fungi but moderate activity against Gram-negative bacteria. Therefore, these compounds may be considered as good antibacterial and antifungal drug discovery. However, substituted ketones (2a–b) as well as chalcone derivatives (3a–c) showed no activity against all the tested strains except for ketone (2c), which showed moderate activity against Candida albicans. PMID:27877017

Reduction of aromatic and heterocyclic aromatic N-hydroxylamines by human cytochrome P450 2S1.

PubMed

Wang, Kai; Guengerich, F Peter

2013-06-17

Many aromatic amines and heterocyclic aromatic amines (HAAs) are known carcinogens for animals, and there is also strong evidence of some in human cancer. The activation of these compounds, including some arylamine drugs, involves N-hydroxylation, usually by cytochrome P450 enzymes (P450) in Family 1 (1A2, 1A1, and 1B1). We previously demonstrated that the bioactivation product of the anticancer agent 2-(4-amino-3-methylphenyl)-5-fluorobenzothiazole (5F 203), an N-hydroxylamine, can be reduced by P450 2S1 to its amine precursor under anaerobic conditions and, to a lesser extent, under aerobic conditions [Wang, K., and Guengerich, F. P. (2012) Chem. Res. Toxicol. 25, 1740-1751]. In the study presented here, we tested the hypothesis that P450 2S1 is involved in the reductive biotransformation of known carcinogenic aromatic amines and HAAs. The N-hydroxylamines of 4-aminobiphenyl (4-ABP), 2-naphthylamine (2-NA), and 2-aminofluorene (2-AF) were synthesized and found to be reduced by P450 2S1 under both anaerobic and aerobic conditions. The formation of amines due to P450 2S1 reduction also occurred under aerobic conditions but was less apparent because the competitive disproportionation reactions (of the N-hydroxylamines) also yielded amines. Further, some nitroso and nitro derivatives of the arylamines could also be reduced by P450 2S1. None of the amines tested were oxidized by P450 2S1. These results suggest that P450 2S1 may be involved in the reductive detoxication of several of the activated products of carcinogenic aromatic amines and HAAs.

Reduction of Aromatic and Heterocyclic Aromatic N-Hydroxylamines by Human Cytochrome P450 2S1

PubMed Central

Wang, Kai; Guengerich, F. Peter

2013-01-01

Many aromatic amines and heterocyclic aromatic amines (HAAs) are known carcinogens for animals and there is also strong evidence for some in human cancer. The activation of these compounds, including some arylamine drugs, involves N-hydroxylation, usually by cytochrome P450 enzymes (P450) in Family 1 (1A2, 1A1, and 1B1). We previously demonstrated that the bioactivation product of the anti-cancer agent 2-(4-amino-3-methylphenyl)-5-fluorobenzothiazole (5F 203), an N-hydroxylamine, can be reduced by P450 2S1 to its amine precursor under anaerobic conditions and, to a lesser extent, under aerobic conditions (Wang, K., and Guengerich, F. P. (2012) Chem. Res. Toxicol. 25, 1740–1751). In the present study, we tested the hypothesis that P450 2S1 is involved in the reductive biotransformation of known carcinogenic aromatic amines and HAAs. The N-hydroxylamines of 4-aminobiphenyl (4-ABP), 2-naphthylamine (2-NA), and 2-aminofluorene (2-AF) were synthesized and found to be reduced by P450 2S1 under both anaerobic and aerobic conditions. The formation of amines due to P450 2S1 reduction also occurred under aerobic conditions but was less apparent because the competitive disproportionation reactions (of the N-hydroxylamines) also yielded amines. Further, some nitroso and nitro derivatives of the arylamines could also be reduced by P450 2S1. None of the amines tested were oxidized by P450 2S1. These results suggest that P450 2S1 may be involved in the reductive detoxication of several of the activated products of carcinogenic aromatic amines and HAAs. PMID:23682735

Hydrolates from lavender (Lavandula angustifolia)--their chemical composition as well as aromatic, antimicrobial and antioxidant properties.

PubMed

Prusinowska, Renata; Śmigielski, Krzysztof; Stobiecka, Agnieszka; Kunicka-Styczyńska, Alina

2016-01-01

It was shown that the method for obtaining hydrolates from lavender (Lavandula angustifolia) influences the content of active compounds and the aromatic, antimicrobial and antioxidant properties of the hydrolates. The content of volatile organic compounds ranged from 9.12 to 97.23 mg/100 mL of hydrolate. Lavender hydrolate variants showed low antimicrobial activity (from 0% to 0.05%). The radical scavenging activity of DPPH was from 3.6 ± 0.5% to 3.8 ± 0.6% and oxygen radical absorbance capacity (ORAC(FL)) results were from 0 to 266 μM Trolox equivalent, depending on the hydrolate variant.

Bio-Based Aromatic Epoxy Monomers for Thermoset Materials.

PubMed

Ng, Feifei; Couture, Guillaume; Philippe, Coralie; Boutevin, Bernard; Caillol, Sylvain

2017-01-18

The synthesis of polymers from renewable resources is a burning issue that is actively investigated. Polyepoxide networks constitute a major class of thermosetting polymers and are extensively used as coatings, electronic materials, adhesives. Owing to their outstanding mechanical and electrical properties, chemical resistance, adhesion, and minimal shrinkage after curing, they are used in structural applications as well. Most of these thermosets are industrially manufactured from bisphenol A (BPA), a substance that was initially synthesized as a chemical estrogen. The awareness on BPA toxicity combined with the limited availability and volatile cost of fossil resources and the non-recyclability of thermosets implies necessary changes in the field of epoxy networks. Thus, substitution of BPA has witnessed an increasing number of studies both from the academic and industrial sides. This review proposes to give an overview of the reported aromatic multifunctional epoxide building blocks synthesized from biomass or from molecules that could be obtained from transformed biomass. After a reminder of the main glycidylation routes and mechanisms and the recent knowledge on BPA toxicity and legal issues, this review will provide a brief description of the main natural sources of aromatic molecules. The different epoxy prepolymers will then be organized from simple, mono-aromatic di-epoxy, to mono-aromatic poly-epoxy, to di-aromatic di-epoxy compounds, and finally to derivatives possessing numerous aromatic rings and epoxy groups.

A Survey of Chemical Compositions and Biological Activities of Yemeni Aromatic Medicinal Plants

PubMed Central

Chhetri, Bhuwan K.; Awadh Ali, Nasser A.; Setzer, William N.

2015-01-01

Yemen is a small country located in the southwestern part of the Arabian Peninsula. Yemen’s coastal lowlands, eastern plateau, and deserts give it a diverse topography, which along with climatic factors make it opulent in flora. Despite the introduction of Western medicinal system during the middle of the twentieth century, herbal medicine still plays an important role in Yemen. In this review, we present a survey of several aromatic plants used in traditional medicine in Yemen, their traditional uses, their volatile chemical compositions, and their biological activities. PMID:28930202

Tailoring ZSM-5 Zeolites for the Fast Pyrolysis of Biomass to Aromatic Hydrocarbons.

PubMed

Hoff, Thomas C; Gardner, David W; Thilakaratne, Rajeeva; Wang, Kaige; Hansen, Thomas W; Brown, Robert C; Tessonnier, Jean-Philippe

2016-06-22

The production of aromatic hydrocarbons from cellulose by zeolite-catalyzed fast pyrolysis involves a complex reaction network sensitive to the zeolite structure, crystallinity, elemental composition, porosity, and acidity. The interplay of these parameters under the reaction conditions represents a major roadblock that has hampered significant improvement in catalyst design for over a decade. Here, we studied commercial and laboratory-synthesized ZSM-5 zeolites and combined data from 10 complementary characterization techniques in an attempt to identify parameters common to high-performance catalysts. Crystallinity and framework aluminum site accessibility were found to be critical to achieve high aromatic yields. These findings enabled us to synthesize a ZSM-5 catalyst with enhanced activity, which offers the highest aromatic hydrocarbon yield reported to date. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

1H NMR analysis of complexation of hydrotropic agents nicotinamide and caffeine with aromatic biologically active molecules in aqueous solution

NASA Astrophysics Data System (ADS)

Lantushenko, Anastasia O.; Mukhina, Yulia V.; Veselkov, Kyrill A.; Davies, David B.; Veselkov, Alexei N.

2004-07-01

NMR spectroscopy has been used to elucidate the molecular mechanism of solubilization action of hydrotropic agents nicotinamide (NA) and caffeine (CAF). Hetero-association of NA with riboflavine-mononucleotide (FMN) and CAF with low soluble in aqueous solution synthetic analogue of antibiotic actinomycin D, actinocyl-bis-(3-dimethylaminopropyl) amine (Actill), has been investigated by 500 MHz 1H NMR spectroscopy. Concentration and temperature dependences of proton chemical shifts have been analysed in terms of a statistical-thermodynamic model of indefinite self- and heteroassociation of aromatic molecules. The obtained results enable to conclude that NA-FMN and CAF-Actill intermolecular complexes are mainly stabilized by the stacking interactions of the aromatic chromophores. Hetero-association of the investigated molecules plays an important role in solubilization of aromatic drugs by hydrotropic agents nicotinamide and caffeine.

Fungal lactone ring opening of 6', 7'-dihydroxybergamottin diminishes cytochrome P450 3A4 inhibitory activity

USDA-ARS?s Scientific Manuscript database

Furanocoumarins (FCs) are a class of aromatic compounds in grapefruit that inhibit human intestinal cytochrome P450 3A4 (CYP3A4). Since fungi metabolize polycyclic aromatic hydrocarbons, we hypothesized that certain fungi might also metabolize FCs into forms that may be inactive as CYP3A4 inhibitors...

New Synthesis Of Poly(1,3,4-Oxadiazoles)

NASA Technical Reports Server (NTRS)

Connell, John W.; Hergenrother, Paul M.; Wolf, Peter

1992-01-01

Synthesis via aromatic nucleophilic displacement yields new high-molecular-weight polymers. Polymers exhibited good mechanical and thermal properties. Synthetic route provided high-molecular-weight POX of new chemical structure, potentially more economical. Availability of large variety of activated aromatic dihalides, facilitates variation of chemical structures. Exhibit properties making them useful as films. Also useful in coatings, adhesives, moldings, and composites.

Organocatalytic asymmetric arylation of indoles enabled by azo groups

NASA Astrophysics Data System (ADS)

Qi, Liang-Wen; Mao, Jian-Hui; Zhang, Jian; Tan, Bin

2018-01-01

Arylation is a fundamental reaction that can be mostly fulfilled by electrophilic aromatic substitution and transition-metal-catalysed aryl functionalization. Although the azo group has been used as a directing group for many transformations via transition-metal-catalysed aryl carbon-hydrogen (C-H) bond activation, there remain significant unmet challenges in organocatalytic arylation. Here, we show that the azo group can effectively act as both a directing and activating group for organocatalytic asymmetric arylation of indoles via formal nucleophilic aromatic substitution of azobenzene derivatives. Thus, a wide range of axially chiral arylindoles have been achieved in good yields with excellent enantioselectivities by utilizing chiral phosphoric acid as catalyst. Furthermore, highly enantioenriched pyrroloindoles bearing two contiguous quaternary chiral centres have also been obtained via a cascade enantioselective formal nucleophilic aromatic substitution-cyclization process. This strategy should be useful in other related research fields and will open new avenues for organocatalytic asymmetric aryl functionalization.

Organocatalytic asymmetric arylation of indoles enabled by azo groups.

PubMed

Qi, Liang-Wen; Mao, Jian-Hui; Zhang, Jian; Tan, Bin

2018-01-01

Arylation is a fundamental reaction that can be mostly fulfilled by electrophilic aromatic substitution and transition-metal-catalysed aryl functionalization. Although the azo group has been used as a directing group for many transformations via transition-metal-catalysed aryl carbon-hydrogen (C-H) bond activation, there remain significant unmet challenges in organocatalytic arylation. Here, we show that the azo group can effectively act as both a directing and activating group for organocatalytic asymmetric arylation of indoles via formal nucleophilic aromatic substitution of azobenzene derivatives. Thus, a wide range of axially chiral arylindoles have been achieved in good yields with excellent enantioselectivities by utilizing chiral phosphoric acid as catalyst. Furthermore, highly enantioenriched pyrroloindoles bearing two contiguous quaternary chiral centres have also been obtained via a cascade enantioselective formal nucleophilic aromatic substitution-cyclization process. This strategy should be useful in other related research fields and will open new avenues for organocatalytic asymmetric aryl functionalization.

Aromatic Medicinal Plants of the Lamiaceae Family from Uzbekistan: Ethnopharmacology, Essential Oils Composition, and Biological Activities

PubMed Central

Mamadalieva, Nilufar Z.; Akramov, Davlat Kh.; Ovidi, Elisa; Tiezzi, Antonio; Nahar, Lutfun; Azimova, Shahnoz S.; Sarker, Satyajit D.

2017-01-01

Plants of the Lamiaceae family are important ornamental, medicinal, and aromatic plants, many of which produce essential oils that are used in traditional and modern medicine, and in the food, cosmetics, and pharmaceutical industry. Various species of the genera Hyssopus, Leonurus, Mentha, Nepeta, Origanum, Perovskia, Phlomis, Salvia, Scutellaria, and Ziziphora are widespread throughout the world, are the most popular plants in Uzbek traditional remedies, and are often used for the treatment of wounds, gastritis, infections, dermatitis, bronchitis, and inflammation. Extensive studies of the chemical components of these plants have led to the identification of many compounds, as well as essentials oils, with medicinal and other commercial values. The purpose of this review is to provide a critical overview of the literature surrounding the traditional uses, ethnopharmacology, biological activities, and essential oils composition of aromatic plants of the family Lamiaceae, from the Uzbek flora. PMID:28930224

Multiscale Evaluation of Catalytic Upgrading of Biomass Pyrolysis Vapors on Ni- and Ga-Modified ZSM-5

DOE PAGES

Yung, Matthew M.; Stanton, Alexander R.; Iisa, Kristiina; ...

2016-10-07

Metal-impregnated (Ni or Ga) ZSM-5 catalysts were studied for biomass pyrolysis vapor upgrading to produce hydrocarbons using three reactors constituting a 100 000x change in the amount of catalyst used in experiments. Catalysts were screened for pyrolysis vapor phase upgrading activity in two small-scale reactors: (i) a Pyroprobe with a 10 mg catalyst in a fixed bed and (ii) a fixed-bed reactor with 500 mg of catalyst. The best performing catalysts were then validated with a larger scale fluidized-bed reactor (using ~1 kg of catalyst) that produced measurable quantities of bio-oil for analysis and evaluation of mass balances. Despite somemore » inherent differences across the reactor systems (such as residence time, reactor type, analytical techniques, mode of catalyst and biomass feed) there was good agreement of reaction results for production of aromatic hydrocarbons, light gases, and coke deposition. Relative to ZSM-5, Ni or Ga addition to ZSM-5 increased production of fully deoxygenated aromatic hydrocarbons and light gases. In the fluidized bed reactor, Ga/ZSM-5 slightly enhanced carbon efficiency to condensed oil, which includes oxygenates in addition to aromatic hydrocarbons, and reduced oil oxygen content compared to ZSM-5. Ni/ZSM-5, while giving the highest yield of fully deoxygenated aromatic hydrocarbons, gave lower overall carbon efficiency to oil but with the lowest oxygen content. Reaction product analysis coupled with fresh and spent catalyst characterization indicated that the improved performance of Ni/ZSM-5 is related to decreasing deactivation by coking, which keeps the active acid sites accessible for the deoxygenation and aromatization reactions that produce fully deoxygenated aromatic hydrocarbons. The addition of Ga enhances the dehydrogenation activity of the catalyst, which leads to enhanced olefin formation and higher fully deoxygenated aromatic hydrocarbon yields compared to unmodified ZSM-5. Catalyst characterization by ammonia temperature programmed desorption, surface area measurements, and postreaction temperature-programmed oxidation (TPO) also showed that the metal-modified zeolites retained a greater percentage of their initial acidity and surface area, which was consistent between the reactor scales. These results demonstrate that the trends observed with smaller (milligram to gram) catalyst reactors are applicable to larger, more industrially relevant (kg) scales to help guide catalyst research toward application.« less

Structural and thermodynamic analysis of the hetero-association of theophylline with aromatic drug molecules

NASA Astrophysics Data System (ADS)

Andrejuk, D. D.; Hernandez Santiago, A. A.; Khomich, V. V.; Voronov, V. K.; Davies, D. B.; Evstigneev, M. P.

2008-10-01

The hetero-association of theophylline (THP) with other biologically-active aromatic molecules ( e.g. the anti-cancer drugs daunomycin and novantrone, the antibiotic norfloxacin, the vitamin flavin-mononucleotide and two mutagens ethidium bromide and proflavine) has been studied by NMR in aqueous-salt solution (0.1 M Na-phosphate buffer, p D 7.1). It was found that THP shows an essentially similar hetero-association ability as caffeine (CAF) towards aromatic drugs, except for novantrone (NOV), which has much less affinity to THP than CAF as a result of energetically unfavourable orthogonal orientation of the chromophores of THP and NOV in the hetero-complex.

Delayed myelosuppression with acute exposure to hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and environmental degradation product hexahydro-1-nitroso-3,5-dinitro-1,3,5-triazine (MNX) in rats.

PubMed

Jaligama, Sridhar; Kale, Vijay M; Wilbanks, Mitchell S; Perkins, Edward J; Meyer, Sharon A

2013-02-01

Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), a widely used munitions compound, and hexahydro-1-nitroso-3,5-dinitro-1,3,5-triazine (MNX), its N-nitroso product of anaerobic microbial nitroreduction, are contaminants of military sites. Previous studies have shown MNX to be the most acutely toxic among the nitroreduced degradation products of RDX and to cause mild anemia at high dose. The present study compares hematotoxicity with acute oral exposure to MNX with parent RDX. Both RDX and MNX caused a modest decrease in blood hemoglobin and ~50% loss of granulocytes (NOAELs=47 mg/kg) in female Sprague-Dawley rats observed 14 days post-exposure. We explored the possibility that blood cell loss observed after 14 days was delayed in onset because of toxicity to bone marrow (BM) progenitors. RDX and MNX decreased granulocyte/macrophage-colony forming cells (GM-CFCs) at 14, but not 7, days (NOAELs=24 mg/kg). The earliest observed time at which MNX decreased GM-CFCs was 10 days post-exposure. RDX and MNX likewise decreased BM burst-forming units-erythroid (BFU-Es) at 14, but not 7, days. Granulocyte-erythrocyte-monocyte-megakaryocyte (GEMM)-CFCs were unaffected by RDX and MNX at 7 days suggesting precursor depletion did not account for GM-CFC and BFU-E loss. MNX added to the culture media was without effect on GM-CFC formation indicating no direct inhibition. Flow cytometry showed no differential loss of BM multilineage progenitors (Thy1.1(+)) or erythroid (CD71(+)) precursors with MNX suggesting myeloid and erythroid lineages were comparably affected. Collectively, these data indicate that acute exposure to both RDX and MNX caused delayed suppression of myelo- and erythropoiesis with subsequent decrease of peripheral granulocytes and erythrocytes. Copyright © 2012 Elsevier Inc. All rights reserved.

Selective hydrodesulfurization of 4,6-dimethyl-dibenzothiophene in the dominant presence of naphthalene over hybrid CoMo/Al{sub 2}O{sub 3} and Ru/Al{sub 2}O{sub 3} catalysts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Isoda, Takaaki; Nagao, Shinichi; Ma, Xiaoliang

1995-12-31

It has been revealed that significant desulfurization of refractory 4-methyldibenzothiophene and 4,6-dimethyldibenzothiophene (4,6-DMDBT) is very essential to achive the low sulfur level of gas oil requested by the current regulation. Their direct desulfurization through the interaction of their sulfur atom with the catalyst surface is sterically hindered by its neighbouring methyl groups. The substrate is found kinetically to be hydrogenated at one of its phenyl rings prior to the desulfurization in order to reduce the steric hindrance through non-planaring configuration (2-4). NiMo / Al{sub 2}O{sub 3} was reported to be superior to CoMo / Al{sub 2}O{sub 3} in the deepmore » desulufurization, because of its higher hydrogenation activity. However, such a hydrogenation route suffers severe inhibition by aromatic species in their dominant presence, because 4,6-DMDBT must compete with the aromatic species to the hydrogenation sites on the catalysts. The aromatic species up to 30 wt % in the gas oil was that completely stop the desulfurization of the particular substrate. The catalyst for the selective hydrogenation of 4,6-DMDBT in the dominant aromatic partners is most wanted to achive its extensive desulfurization in the gas oil, although there have been reported activities of various transition metal sulfides for HDS of dibenzothiophene, and hydrogenation of aromatic hydrocarbons.« less

Docking and QSAR comparative studies of polycyclic aromatic hydrocarbons and other procarcinogen interactions with cytochromes P450 1A1 and 1B1.

PubMed

Gonzalez, J; Marchand-Geneste, N; Giraudel, J L; Shimada, T

2012-01-01

To obtain chemical clues on the process of bioactivation by cytochromes P450 1A1 and 1B1, some QSAR studies were carried out based on cellular experiments of the metabolic activation of polycyclic aromatic hydrocarbons and heterocyclic aromatic compounds by those enzymes. Firstly, the 3D structures of cytochromes 1A1 and 1B1 were built using homology modelling with a cytochrome 1A2 template. Using these structures, 32 ligands including heterocyclic aromatic compounds, polycyclic aromatic hydrocarbons and corresponding diols, were docked with LigandFit and CDOCKER algorithms. Binding mode analysis highlighted the importance of hydrophobic interactions and the hydrogen bonding network between cytochrome amino acids and docked molecules. Finally, for each enzyme, multilinear regression and artificial neural network QSAR models were developed and compared. These statistical models highlighted the importance of electronic, structural and energetic descriptors in metabolic activation process, and could be used for virtual screening of ligand databases. In the case of P450 1A1, the best model was obtained with artificial neural network analysis and gave an r (2) of 0.66 and an external prediction [Formula: see text] of 0.73. Concerning P450 1B1, artificial neural network analysis gave a much more robust model, associated with an r (2) value of 0.73 and an external prediction [Formula: see text] of 0.59.

Structure-Activity Relationships for Rates of Aromatic Amine Oxidation by Manganese Dioxide

DOE PAGES

Salter-Blanc, Alexandra J.; Bylaska, Eric J.; Lyon, Molly A.; ...

2016-04-13

New energetic compounds are designed to minimize their potential environmental impacts, which includes their transformation and the fate and effects of their transformation products. The nitro groups of energetic compounds are readily reduced to amines, and the resulting aromatic amines are subject to oxidation and coupling reactions. Manganese dioxide (MnO 2) is a common environmental oxidant and model system for kinetic studies of aromatic amine oxidation. Here in this study, a training set of new and previously reported kinetic data for the oxidation of model and energetic-derived aromatic amines was assembled and subjected to correlation analysis against descriptor variables that ranged from general purpose [Hammettmore » $$\\sigma$$ constants ($$\\sigma^-$$), pK as of the amines, and energies of the highest occupied molecular orbital (E HOMO)] to specific for the likely rate-limiting step [one-electron oxidation potentials (E ox)]. The selection of calculated descriptors (pK a), E HOMO, and E ox) was based on validation with experimental data. All of the correlations gave satisfactory quantitative structure-activity relationships (QSARs), but they improved with the specificity of the descriptor. The scope of correlation analysis was extended beyond MnO 2 to include literature data on aromatic amine oxidation by other environmentally relevant oxidants (ozone, chlorine dioxide, and phosphate and carbonate radicals) by correlating relative rate constants (normalized to 4-chloroaniline) to E HOMO (calculated with a modest level of theory).« less

Evidence for behavioral attractiveness of methoxylated aromatics in a dynastid scarab beetle-pollinated araceae.

PubMed

Dötterl, Stefan; David, Anja; Boland, Wilhelm; Silberbauer-Gottsberger, Ilse; Gottsberger, Gerhard

2012-12-01

Many plants attract their pollinators with floral scents, and these olfactory signals are especially important at night, when visual signals become inefficient. Dynastid scarab beetles are a speciose group of night-active pollinators, and several plants pollinated by these insects have methoxylated aromatic compounds in their scents. However, there is a large gap in our knowledge regarding the compounds responsible for beetle attraction. We used chemical analytical analyses to determine temporal patterns of scent emission and the composition of scent released from inflorescences of Philodendron selloum. The attractiveness of the main components in the scent to the dynastid scarab beetle Erioscelis emarginata, the exclusive pollinator of this plant, was assessed in field biotests. The amount of scent increased rapidly in the evening, and large amounts of scent were released during the activity time of the beetle pollinators. Inflorescences emitted a high number of compounds of different biosynthetic origin, among them both uncommon and also widespread flower scents. Methoxylated aromatic compounds dominated the scent, and 4-methoxystyrene, the most abundant compound, attracted E. emarginata beetles. Other compounds, such as (Z)-jasmone and possibly also the methoxylated aromatic compound 3,4-dimethoxystyrene increased the attractiveness of 4-methoxystyrene. Methoxylated aromatics, which are known from other dynastid pollinated plants as well, are important signals in many scarab beetles in a different context (e.g., pheromones), thus suggesting that these plants exploit pre-existing preferences of the beetles for attracting this group of insects as pollinators.

Structure-Activity Relationships for Rates of Aromatic Amine Oxidation by Manganese Dioxide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Salter-Blanc, Alexandra J.; Bylaska, Eric J.; Lyon, Molly A.

New energetic compounds are designed to minimize their potential environmental impacts, which includes their transformation and the fate and effects of their transformation products. The nitro groups of energetic compounds are readily reduced to amines, and the resulting aromatic amines are subject to oxidation and coupling reactions. Manganese dioxide (MnO 2) is a common environmental oxidant and model system for kinetic studies of aromatic amine oxidation. Here in this study, a training set of new and previously reported kinetic data for the oxidation of model and energetic-derived aromatic amines was assembled and subjected to correlation analysis against descriptor variables that ranged from general purpose [Hammettmore » $$\\sigma$$ constants ($$\\sigma^-$$), pK as of the amines, and energies of the highest occupied molecular orbital (E HOMO)] to specific for the likely rate-limiting step [one-electron oxidation potentials (E ox)]. The selection of calculated descriptors (pK a), E HOMO, and E ox) was based on validation with experimental data. All of the correlations gave satisfactory quantitative structure-activity relationships (QSARs), but they improved with the specificity of the descriptor. The scope of correlation analysis was extended beyond MnO 2 to include literature data on aromatic amine oxidation by other environmentally relevant oxidants (ozone, chlorine dioxide, and phosphate and carbonate radicals) by correlating relative rate constants (normalized to 4-chloroaniline) to E HOMO (calculated with a modest level of theory).« less

Microbial transformation of nitroaromatic compounds in sewage effluent.

PubMed

Hallas, L E; Alexander, M

1983-04-01

The transformation of mono- and dinitroaromatic compounds was measured in sewage effluent maintained under aerobic or anaerobic conditions. Most of the nitrobenzene, 3- and 4-nitrobenzoic acids, and 3- and 4-nitrotoluenes and much of the 1,2- and 1,3-dinitrobenzenes disappeared both in the presence and absence of oxygen. Under anaerobiosis, 2,6-dinitrotoluene and 3,5-dinitrobenzoic acid disappeared slowly, but no loss was evident in 28 days in aerated sewage. Aromatic amines did not accumulate during the aerobic decomposition of the mononitro compounds. They did appear in nonsterile, but not in sterile, sewage incubated aerobically with the dinitro compounds and anaerobically with all the chemicals. Analysis by gas chromatography and combined gas chromatography-mass spectrometry showed that aniline was formed from nitrobenzene, toluidine was formed from 3- and 4-nitrotoluenes, and aminobenzoic acid was formed from 3- and 4-nitrobenzoic acids under anaerobiosis, and that nitroaniline was formed from 1,2- and 1,3-dinitrobenzenes, aminonitrotoluene resulted from 2,6-dinitrotoluene, and aminonitrobenzoic acid was a product of 3,5-dinitrobenzoic acid under both conditions. The isomeric forms of the metabolites were not established. Aniline, 4-toluidine, and 4-aminobenzoic acid added to sewage disappeared from aerated nonsterile, but not from sterile, sewage or sewage in the absence of oxygen. 2-Nitroaniline, 2-amino-3-nitrotoluene, and 2-amino-5-nitrobenzoic acid added to sewage persisted for at least 60 days in aerobic or anaerobic conditions. Gas chromatographic and gas chromatographic-mass spectrometric analyses demonstrated that acetanilide and 2-methylquinoline were formed from aniline, 4-methylformanilide and 4-methylacetanilide were formed from 4-toluidine, 2-methylbenzimidazole was a product of 2-nitroaniline, and unidentified benzimidazoles were formed from 2-amino-3-nitrotoluene in the absence of oxygen, and that 2-nitroacetanilide and 2-methyl-6-nitroacetanilide were formed from 2-nitroaniline and 2-amino-3-nitrotoluene, respectively, in the presence or absence of oxygen. It is suggested that the transformations of widely used nitroaromatic compounds should be further studied because of the persistence and possible toxicity of products of their metabolism.

Microbial Transformation of Nitroaromatic Compounds in Sewage Effluent

PubMed Central

Hallas, Laurence E.; Alexander, Martin

1983-01-01

The transformation of mono- and dinitroaromatic compounds was measured in sewage effluent maintained under aerobic or anaerobic conditions. Most of the nitrobenzene, 3- and 4-nitrobenzoic acids, and 3- and 4-nitrotoluenes and much of the 1,2- and 1,3-dinitrobenzenes disappeared both in the presence and absence of oxygen. Under anaerobiosis, 2,6-dinitrotoluene and 3,5-dinitrobenzoic acid disappeared slowly, but no loss was evident in 28 days in aerated sewage. Aromatic amines did not accumulate during the aerobic decomposition of the mononitro compounds. They did appear in nonsterile, but not in sterile, sewage incubated aerobically with the dinitro compounds and anaerobically with all the chemicals. Analysis by gas chromatography and combined gas chromatography-mass spectrometry showed that aniline was formed from nitrobenzene, toluidine was formed from 3- and 4-nitrotoluenes, and aminobenzoic acid was formed from 3- and 4-nitrobenzoic acids under anaerobiosis, and that nitroaniline was formed from 1,2- and 1,3-dinitrobenzenes, aminonitrotoluene resulted from 2,6-dinitrotoluene, and aminonitrobenzoic acid was a product of 3,5-dinitrobenzoic acid under both conditions. The isomeric forms of the metabolites were not established. Aniline, 4-toluidine, and 4-aminobenzoic acid added to sewage disappeared from aerated nonsterile, but not from sterile, sewage or sewage in the absence of oxygen. 2-Nitroaniline, 2-amino-3-nitrotoluene, and 2-amino-5-nitrobenzoic acid added to sewage persisted for at least 60 days in aerobic or anaerobic conditions. Gas chromatographic and gas chromatographic-mass spectrometric analyses demonstrated that acetanilide and 2-methylquinoline were formed from aniline, 4-methylformanilide and 4-methylacetanilide were formed from 4-toluidine, 2-methylbenzimidazole was a product of 2-nitroaniline, and unidentified benzimidazoles were formed from 2-amino-3-nitrotoluene in the absence of oxygen, and that 2-nitroacetanilide and 2-methyl-6-nitroacetanilide were formed from 2-nitroaniline and 2-amino-3-nitrotoluene, respectively, in the presence or absence of oxygen. It is suggested that the transformations of widely used nitroaromatic compounds should be further studied because of the persistence and possible toxicity of products of their metabolism. PMID:6859845

Synthetic musk fragrances in environmental Standard Reference Materials.

PubMed

Peck, Aaron M; Kucklick, John R; Schantz, Michele M

2007-04-01

Synthetic musk fragrances have been measured in water, air, sediments, sewage sludge, and biota worldwide. As the study of the environmental fate and impacts of these compounds progresses, the need for Standard Reference Materials (SRMs) for these compounds to facilitate analytical method improvement and interlaboratory comparisons becomes increasingly important. The National Institute of Standards and Technology (NIST) issues environmental matrix SRMs with certified concentrations for a variety of persistent organic pollutants including polycyclic aromatic hydrocarbons (PAHs), chlorinated pesticides, and polychlorinated biphenyl congeners (PCBs). Until now synthetic musk fragrance concentrations have not been reported in NIST SRMs. The objective of this study was to provide reference values for several commonly detected synthetic musk fragrances in several NIST natural matrix SRMs. In this study five polycyclic musk fragrances [HHCB (1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta-gamma-2-benzopyran), AHTN (7-acetyl-1,1,3,4,4,6-hexamethyl-1,2,3,4-tetrahydronaphthalene), ADBI (4-acetyl-1,1-dimethyl-6-tert-butylindane), AHMI (6-acetyl-1,1,2,3,3,5-hexamethylindane), and ATII (5-acetyl-1,1,2,6-tetramethyl-3-isopropylindane] and two nitro musk fragrances [musk xylene (1-tert-butyl-3,5-dimethyl-2,4,6-trinitrobenzene) and musk ketone (4-tert-butyl-3,5-dinitro-2,6-dimethylacetophenone)] were measured in selected environmental SRMs. Gas chromatography-electron impact mass spectrometry (GC/EI-MS) was used for all analyses. HHCB was the most frequently detected synthetic musk fragrance and was detected in SRM 2585 Organic Contaminants in House Dust, SRM 2781 Domestic Sludge, SRM 1974b Organics in Mussel Tissue (Mytilus edulis), and SRM 1947 Lake Michigan Fish Tissue. It was not detected in SRM 1946 Lake Superior Fish Tissue or SRM 1945 Organics in Whale Blubber. Concentrations of HHCB in these SRMs ranged from 1.12 ng/g in SRM 1947 to 92,901 ng/g in SRM 2781. All of the polycyclic musk fragrances were detected in SRM 2781 and all of the target compounds were detected in SRM 2585.

Comparative study of chemical composition and antioxidant activity of fresh and dry rhizomes of turmeric (Curcuma longa Linn.).

PubMed

Singh, G; Kapoor, I P S; Singh, Pratibha; de Heluani, Carola S; de Lampasona, Marina P; Catalan, Cesar A N

2010-04-01

The phytoconstituents of essential oil and ethanol oleoresin of fresh and dry rhizomes of turmeric (Curcuma longa Linn.) were analyzed by GC-MS. The major constituents were aromatic-turmerone (24.4%), alpha-turmerone (20.5%) and beta-turmerone (11.1%) in fresh rhizome and aromatic-turmerone (21.4%), alpha-santalene (7.2%) and aromatic-curcumene (6.6%) in dry rhizome oil. Whereas, in oleoresins, the major components were alpha-turmerone (53.4%), beta-turmerone (18.1%) and aromatic-turmerone (6.2%) in fresh and aromatic-turmerone (9.6%), alpha-santalene (7.8%) and alpha-turmerone (6.5%) in dry rhizome. Results showed that alpha-turmerone, a major component in fresh rhizomes is only minor one in dry rhizomes. Also, the content of beta-turmerone in dry rhizomes is less than a half amount found in fresh rhizomes. The antioxidant properties have been assessed by various lipid peroxidation assays as well as DPPH radical scavenging and metal chelating methods. The essential oil and ethanol oleoresin of fresh rhizomes have higher antioxidant properties as compared dry ones. 2010 Elsevier Ltd. All rights reserved.

In silico and experimental methods revealed highly diverse bacteria with quorum sensing and aromatics biodegradation systems--a potential broad application on bioremediation.

PubMed

Huang, Yili; Zeng, Yanhua; Yu, Zhiliang; Zhang, Jing; Feng, Hao; Lin, Xiuchun

2013-11-01

Phylogenetic overlaps between aromatics-degrading bacteria and acyl-homoserine-lactone (AHL) or autoinducer (AI) based quorum-sensing (QS) bacteria were evident in literatures; however, the diversity of bacteria with both activities had never been finely described. In-silico searching in NCBI genome database revealed that more than 11% of investigated population harbored both aromatic ring-hydroxylating-dioxygenase (RHD) gene and AHL/AI-synthetase gene. These bacteria were distributed in 10 orders, 15 families, 42 genus and 78 species. Horizontal transfers of both genes were common among them. Using enrichment and culture dependent method, 6 Sphingomonadales and 4 Rhizobiales with phenanthrene- or pyrene-degrading ability and AHL-production were isolated from marine, wetland and soil samples. Thin-layer-chromatography and gas-chromatography-mass-spectrum revealed that these Sphingomonads produced various AHL molecules. This is the first report of highly diverse bacteria that harbored both aromatics-degrading and QS systems. QS regulation may have broad impacts on aromatics biodegradation, and would be a new angle for developing bioremediation technology. Copyright © 2013 Elsevier Ltd. All rights reserved.

Sources and distribution of aromatic hydrocarbons in a tropical marine protected area estuary under influence of sugarcane cultivation.

PubMed

Arruda-Santos, Roxanny Helen de; Schettini, Carlos Augusto França; Yogui, Gilvan Takeshi; Maciel, Daniele Claudino; Zanardi-Lamardo, Eliete

2018-05-15

Goiana estuary is a well preserved marine protected area (MPA) located on the northeastern coast of Brazil. Despite its current state, human activities in the watershed represent a potential threat to long term local preservation. Dissolved/dispersed aromatic hydrocarbons and polycyclic aromatic hydrocarbons (PAHs) were investigated in water and sediments across the estuarine salt gradient. Concentration of aromatic hydrocarbons was low in all samples. According to results, aromatic hydrocarbons are associated to suspended particulate matter (SPM) carried to the estuary by river waters. An estuarine turbidity maximum (ETM) was identified in the upper estuary, indicating that both sediments and contaminants are trapped prior to an occasional export to the adjacent sea. PAHs distribution in sediments were associated with organic matter and mud content. Diagnostic ratios indicated pyrolytic processes as the main local source of PAHs that are probably associated with sugarcane burning and combustion engines. Low PAH concentrations probably do not cause adverse biological effects to the local biota although their presence indicate anthropogenic contamination and pressure on the Goiana estuary MPA. Copyright © 2017 Elsevier B.V. All rights reserved.

Bio-electrochemical remediation of real field petroleum sludge as an electron donor with simultaneous power generation facilitates biotransformation of PAH: effect of substrate concentration.

PubMed

Chandrasekhar, K; Venkata Mohan, S

2012-04-01

Remediation of real-field petroleum sludge was studied under self-induced electrogenic microenvironment with the function of variable organic loads (OLs) in bio-electrochemical treatment (BET) systems. Operation under various OLs documented marked influence on both electrogenic activity and remediation efficiency. Both total petroleum hydrocarbons (TPH) and its aromatic fraction documented higher removal with OL4 operation followed by OL3, OL2, OL1 and control. Self-induced biopotential and associated multiple bio-electrocatalytic reactions during BET operation facilitated biotransformation of higher ring aromatics (5-6) to lower ring aromatic (2-3) compounds. Asphaltenes and NSO fractions showed negligible removal during BET operation. Higher electrogenic activity was recorded at OL1 (343mV; 53.11mW/m(2), 100Ω) compared to other three OLs operation. Bioaugmentation to anodic microflora with anaerobic culture documented enhanced electrogenic activity at OL4 operation. Voltammetric profiles, Tafel analysis and VFA generation were in agreement with the observed power generation and degradation efficiency. Copyright © 2012 Elsevier Ltd. All rights reserved.

Site-selective arene C-H amination via photoredox catalysis.

PubMed

Romero, Nathan A; Margrey, Kaila A; Tay, Nicholas E; Nicewicz, David A

2015-09-18

Over the past several decades, organometallic cross-coupling chemistry has developed into one of the most reliable approaches to assemble complex aromatic compounds from preoxidized starting materials. More recently, transition metal-catalyzed carbon-hydrogen activation has circumvented the need for preoxidized starting materials, but this approach is limited by a lack of practical amination protocols. Here, we present a blueprint for aromatic carbon-hydrogen functionalization via photoredox catalysis and describe the utility of this strategy for arene amination. An organic photoredox-based catalyst system, consisting of an acridinium photooxidant and a nitroxyl radical, promotes site-selective amination of a variety of simple and complex aromatics with heteroaromatic azoles of interest in pharmaceutical research. We also describe the atom-economical use of ammonia to form anilines, without the need for prefunctionalization of the aromatic component. Copyright © 2015, American Association for the Advancement of Science.

Activity of selected aromatic amino acids in biological systems.

PubMed

Krzyściak, Wirginia

2011-01-01

Besides the structural function in proteins, aromatic amino acids are precursors of many important biological compounds essential for normal functioning of the human organism. Many of these compounds may be used as markers for identification of specific pathological states. Comprehensive knowledge about the metabolism of aromatic amino acids and mechanisms of action of their metabolites made it possible to develop effective treatments for many disorders. However, it should not be forgotten that in some pathological conditions, these compounds could not only be involved in the pathogenesis of many disease entities but could also be used as an important tool in prediction of many diseases. This paper contains a review of published literature on aromatic amino acids in the context of physiological processes of the human body and chosen social disorders, such as cancers; psychiatric disorders: depression, anxiety states, schizophrenia, bipolar affective disorders; neurodegenerative, and cardiovascular diseases; chronic kidney insufficiency or diabetes.

Elaboration of tetra-orthogonally-substituted aromatic scaffolds towards novel EGFR-kinase inhibitors.

PubMed

Close, Adam J; Jones, Rhiannon N; Ocasio, Cory A; Kemmitt, Paul; Roe, S Mark; Spencer, John

2016-09-21

Nitration of three regioisomers of bromo-fluorobenzaldehyde proceeds regioselectively, notably with H2SO4/HNO3 at 0 °C. The thereby synthesized tetrasubstituted aromatics, endowed with orthogonal substituents, can be elaborated via Pd-catalysed coupling, reduction and reductive amination reactions. As a test-case, these compounds were converted into EGFR inhibitors related to Gefitinib, whose activity was rationalised by docking studies.

Asymmetric hydrogenation of aromatic ketones by new recyclable ionic tagged ferrocene-ruthenium catalyst system.

PubMed

Xu, Di; Zhou, Zhi-Ming; Dai, Li; Tang, Li-Wei; Zhang, Jun

2015-05-01

Newly developed ferrocene-oxazoline-phosphine ligands containing quaternary ammonium ionic groups exhibited excellent catalytic performance for the ruthenium-catalyzed hydrogenation of aromatic ketonic substrates to give chiral secondary alcohols with high levels of conversions and enantioselectivities. Simple manipulation process, water tolerance, high activity and good recyclable property make this catalysis practical and appealing. Copyright © 2015 Elsevier Ltd. All rights reserved.

Spectrum of the Reductive Dehalogenation Activity of Desulfitobacterium frappieri PCP-1

PubMed Central

Dennie, D.; Gladu, I.; Lépine, F.; Villemur, R.; Bisaillon, J.-G.; Beaudet, R.

1998-01-01

Desulfitobacterium frappieri PCP-1 was induced for ortho- and para-dechlorinating activities by different chlorophenols. Dehalogenation rates ranging from 25 to 1,158 nmol/min/mg of cell protein were observed according to the chlorophenol tested and the position of the chlorine removed. D. frappieri shows a broad substrate specificity; in addition to tetrachloroethylene and pentachloropyridine, strain PCP-1 can dehalogenate at ortho, meta, and para positions a large variety of aromatic molecules with substituted hydroxyl or amino groups. Reactions of O demethylation and reduction of nitro to amino substituents on aromatic molecules were also observed. PMID:9797330

Tough, high performance, addition-type thermoplastic polymers

NASA Technical Reports Server (NTRS)

Pater, Ruth H. (Inventor)

1992-01-01

A tough, high performance polyimide is provided by reacting a triple bond conjugated with an aromatic ring in a bisethynyl compound with the active double bond in a compound containing a double bond activated toward the formation of a Diels-Adler type adduct, especially a bismaleimide, a biscitraconimide, or a benzoquinone, or mixtures thereof. Addition curing of this product produces a high linear polymeric structure and heat treating the highly linear polymeric structure produces a thermally stable aromatic addition-type thermoplastic polyimide, which finds utility in the preparation of molding compounds, adhesive compositions, and polymer matrix composites.

Arylamine N-acetyltransferase activity in bronchial epithelial cells and its inhibition by cellular oxidants

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dairou, Julien; Petit, Emile; Ragunathan, Nilusha

2009-05-01

Bronchial epithelial cells express xenobiotic-metabolizing enzymes (XMEs) that are involved in the biotransformation of inhaled toxic compounds. The activities of these XMEs in the lung may modulate respiratory toxicity and have been linked to several diseases of the airways. Arylamine N-acetyltransferases (NAT) are conjugating XMEs that play a key role in the biotransformation of aromatic amine pollutants such as the tobacco-smoke carcinogens 4-aminobiphenyl (4-ABP) and {beta}-naphthylamine ({beta}-NA). We show here that functional human NAT1 or its murine counterpart Nat2 are present in different lung epithelial cells i.e. Clara cells, type II alveolar cells and bronchial epithelial cells, thus indicating thatmore » inhaled aromatic amines may undergo NAT-dependent biotransformation in lung epithelium. Exposure of these cells to pathophysiologically relevant amounts of oxidants known to contribute to lung dysfunction, such as H{sub 2}O{sub 2} or peroxynitrite, was found to impair the NAT1/Nat2-dependent cellular biotransformation of aromatic amines. Genetic and non genetic impairment of intracellular NAT enzyme activities has been suggested to compromise the important detoxification pathway of aromatic amine N-acetylation and subsequently to contribute to an exacerbation of untoward effects of these pollutants on health. Our study suggests that oxidative/nitroxidative stress in lung epithelial cells, due to air pollution and/or inflammation, could contribute to local and/or systemic dysfunctions through the alteration of the functions of pulmonary NAT enzymes.« less

Bacterial, Fungal, and Actinomycete Populations in Soils Receiving Repeated Applications of 2,4-Dichlorophenoxyacetic Acid and Trifluralin 1

PubMed Central

Breazeale, F. W.; Camper, N. D.

1970-01-01

Soil samples were collected from an untreated plot and plots receiving repeated applications of 2,4-dichlorophenoxyacetic acid (2,4-D) and α,α,α-trifluoro-2, 6-dinitro-N,N-dipropyl-p-toluidine (trifluralin); they were then plated on media specific for bacteria, fungi, and actinomycetes. The actinomycete colony count in the trifluralin-treated plot was greater than the control, but the same as the control in the 2,4-D-treated plot. The bacterial count was lower in both treated plots. Fungal colonies in the trifluralin-treated plots were greater than the control, but not different from the control in the 2,4-D-treated plot. PMID:5437308

Method and apparatus for synthesizing HMX and N/sub 2/O/sub 5/. [Patent application; cyclotetramethylenetetraamine

DOEpatents

McGuire, R.R.; Coon, C.L.; Harrar, J.E.; Pearson, R.K.

1982-07-20

A method and apparatus for electrochemically synthesizing N/sub 2/O/sub 5/ includes oxidizing a solution of N/sub 2/O/sub 4//HNO/sub 3/ at an anode, while maintaining a controlled potential between the N/sub 2/O/sub 4//HNO/sub 3/ solution and the anode. A potential of about 1.35 to 2.0V vs. SCE is preferred, while a potential of about 1.80V vs. SCE is most preferred. Thereafter, the N/sub 2/O/sub 5/ is reacted with either 1.5-diacetyl-3,7-dinitro-1,3,5,7-tetraazacyclooctane (DADN) or 1,3,5,7-tetraacetyl-1,3,5,7-tetraazacyclooctane (TAT) to form cyclotetramethylenetetraamine (HMX).

Bacteriolytic Activity Of Human Interleukin-2, Chicken Egg Lysozyme In The Presence Of Potential Effectors

PubMed Central

Levashov, P. A.; Matolygina, D. A.; Ovchinnikova, E. D.; Atroshenko, D. L.; Savin, S. S.; Belogurova, N. G.; Smirnov, S. A.; Tishkov, V. I.; Levashov, A. V.

2017-01-01

The bacteriolytic activity of interleukin-2 and chicken egg lysozyme in the presence of various substances has been studied. Glycine and lysine do not affect the activity of interleukin-2 but increase that of lysozyme, showing a bell-shape concentration dependence peaking at 1.5 mM glycine and 18 mM lysine. Arginine and glutamate activate both interleukin-2 and lysozyme with a concentration dependence of the saturation type. Aromatic amino acids have almost no effect on the activity of both interleukin-2 and lysozyme. Aromatic amines, tryptamine, and tyramine activate interleukin-2 but inhibit lysozyme. Peptide antibiotics affect interleukin and lysozyme similarly and exhibit maximum activity in the micromolar range of antibiotics. Taurine has no effect on the activity of interleukin-2 and lysozyme. Mildronate showed no influence on lysozyme, but it activated interleukin-2 with the activity maximum at 3 mM. EDTA activates both interleukin-2 and lysozyme at concentrations above 0.15 mM. PMID:28740730

QSAR studies on carbonic anhydrase inhibitors: a case of ureido and thioureido derivatives of aromatic/heterocyclic sulfonamides.

PubMed

Agrawal, Vijay K; Sharma, Ruchi; Khadikar, Padmakar V

2002-09-01

QSAR studies on modelling of biological activity (hCAI) for a series of ureido and thioureido derivatives of aromatic/heterocyclic sulfonamides have been made using a pool of topological indices. Regression analysis of the data showed that excellent results were obtained in multiparametric correlations upon introduction of indicator parameters. The predictive abilities of the models are discussed using cross-validation parameters.

Identification of mammalian cell genotoxins in respirable diesel exhaust particles by bioassay-directed chemical analysis.

PubMed

Oh, Seung-Min; Chung, Kyu-Hyuck

2006-03-01

A bioassay-directed chemical analysis which consists of mammalian cell bioassays (comet assay, CBMN assay and EROD-microbioassay) in conjunction with analytical measurements was performed to identify the most biologically active compounds of the diesel exhaust particulate matters (DEPs) on mutagenic activity. These bioassay systems were suitable to estimate the mammalian genotoxic potentials of pollutants present in low concentrations in limited environmental samples, as is the case with DEPEs. The results from mutagenic assay showed that the aromatic and slightly polar fraction of DEPs induced chromosomal damage and DNA breakage in a non-cytotoxic dose. It was also revealed that indirect-acting mutagens may mainly contribute to the mutagenic effect of aromatic fraction via the enzyme metabolism system. In the aromatic fraction, several indirect-acting mutagenic PAHs such as dibenzo(a,h)anthracene, chrysene, and 1,2-benzanthracene were detected by GC-MS and the complex mixture effect of this fraction was quantified in terms of its biological-TCDD equivalent concentration (bio-TEQ) which was 32.82 bio-TEQ ng/g-DEPs by EROD-microbioassay. Conclusively, we confirmed that indirect-acting mutagens contained in aromatic fraction may be important causatives of the genotoxicity of extracts of DEPs by integrating the results obtained from a mammalian cell bioassay-directed fractionation.

Valorization of essential oils from Moroccan aromatic plants.

PubMed

Santana, Omar; Fe Andrés, Maria; Sanz, Jesús; Errahmani, Naima; Abdeslam, Lamiri; González-Coloma, Azucena

2014-08-01

The chemical composition and biological activity of cultivated and wild medicinal and aromatic plants from Morocco (Artemisia herba-alba, Lippia citriodora, Mentha pulegium, M. spicata, Myrtus communis, Rosmarinus officinalis, and Thymus satureioides) are described. The essential oils (EOs) of these species have been analyzed by GC-MS. The antifeedant, nematicidal and phytotoxic activities of the EOs were tested on insect pests (Spodoptera littoralis, Myzus persicae and Rhopalosiphum padi), root-knot nematodes (Meloydogine javanica) and plants (Lactuca sativa, Lolium perenne and Lycopersicum esculentum). EOs from A. herba-alba, M. pulegium and R. officinalis were strong antifeedants against S. littoralis, M. persicae and R. padi. EOs from L. citriodora, M. spicata and T. satureioides showed high nematicidal activity. These biological effects are explained by the activity of the major EO components and/or synergistic effects.

Effect of iodide on transformation of phenolic compounds by nonradical activation of peroxydisulfate in the presence of carbon nanotube: Kinetics, impacting factors, and formation of iodinated aromatic products.

PubMed

Guan, Chaoting; Jiang, Jin; Pang, Suyan; Luo, Congwei; Yang, Yi; Ma, Jun; Yu, Jing; Zhao, Xi

2018-06-04

Our recent study has demonstrated that iodide (I - ) can be easily and almost entirely oxidized to hypoiodous acid (HOI) but not to iodate by nonradical activation of peroxydisulfate (PDS) in the presence of a commercial carbon nanotube (CNT). In this work, the oxidation kinetics of phenolic compounds by the PDS/CNT system in the presence of I - were examined and potential formation of iodinated aromatic products was explored. Experimental results suggested that I - enhanced the transformation of six selected substituted phenols, primarily attributed to the generation of HOI that was considerably reactive toward these phenolic compounds. More significant enhancement was obtained at higher I - concentrations or lower pH values, while the change of PDS or CNT dosages exhibited a slight impact on the enhancing effect of I - . Product analyses with liquid chromatography tandem mass spectrometry clearly revealed the production of iodinated aromatic products when p-hydroxybenzoic acid (p-HBA, a model phenol) was treated by the PDS/CNT/I - system in both synthetic and real waters. Their formation pathways probably involved the substitution of HOI on aromatic ring of p-HBA, as well as the generation of iodinated p-HBA phenoxyl radicals and subsequent coupling of these radicals. Given the considerable toxicity and harmful effects of these iodinated aromatic products, particular attention should be paid when the novel PDS/CNT oxidation technology is applied for treatment of phenolic contaminants in iodide-containing waters. Copyright © 2018 Elsevier Ltd. All rights reserved.

Studies on the Simultaneous Formation of Aroma-Active and Toxicologically Relevant Vinyl Aromatics from Free Phenolic Acids during Wheat Beer Brewing.

PubMed

Langos, Daniel; Granvogl, Michael

2016-03-23

During the brewing process of wheat beer, the desired aroma-active vinyl aromatics 2-methoxy-4-vinylphenol and 4-vinylphenol as well as the undesired and toxicologically relevant styrene are formed from their respective precursors, free ferulic acid, p-coumaric acid, and cinnamic acid, deriving from the malts. Analysis of eight commercial wheat beers revealed high concentrations of 2-methoxy-4-vinylphenol and 4-vinylphenol always in parallel with high concentrations of styrene or low concentrations of the odorants in parallel with low styrene concentrations, suggesting a similar pathway. To better understand the formation of these vinyl aromatics, each process step of wheat beer brewing and the use of different strains of Saccharomyces cerevisiae were evaluated. During wort boiling, only a moderate decarboxylation of free phenolic acids and formation of desired and undesired vinyl aromatics were monitored due to the thermal treatment. In contrast, this reaction mainly occurred enzymatically catalyzed during fermentation with S. cerevisiae strain W68 with normal Pof(+) activity (phenolic off-flavor) resulting in a wheat beer eliciting the typical aroma requested by consumers due to high concentrations of 2-methoxy-4-vinylphenol (1790 μg/L) and 4-vinylphenol (937 μg/L). Unfortunately, also a high concentration of undesired styrene (28.3 μg/L) was observed. Using a special S. cerevisiae strain without Pof(+) activity resulted in a significant styrene reduction (

Opioid receptor probes derived from cycloaddition of the hallucinogen natural product salvinorin A.

PubMed

Lozama, Anthony; Cunningham, Christopher W; Caspers, Michael J; Douglas, Justin T; Dersch, Christina M; Rothman, Richard B; Prisinzano, Thomas E

2011-04-25

As part of our continuing efforts toward more fully understanding the structure-activity relationships of the neoclerodane diterpene salvinorin A, we report the synthesis and biological characterization of unique cycloadducts through [4+2] Diels-Alder cycloaddition. Microwave-assisted methods were developed and successfully employed, aiding in functionalizing the chemically sensitive salvinorin A scaffold. This demonstrates the first reported results for both cycloaddition of the furan ring and functionalization via microwave-assisted methodology of the salvinorin A skeleton. The cycloadducts yielded herein introduce electron-withdrawing substituents and bulky aromatic groups into the C-12 position. Kappa opioid (KOP) receptor space was explored through aromatization of the bent oxanorbornadiene system possessed by the cycloadducts to a planar phenyl ring system. Although dimethyl- and diethylcarboxylate analogues 5 and 6 retain some affinity and selectivity for KOP receptors and are full agonists, their aromatized counterparts 13 and 14 have reduced affinity for KOP receptors. The methods developed herein signify a novel approach toward rapidly probing the structure-activity relationships of furan-containing natural products.

Bisphenol-A alters microbiota metabolites derived from aromatic amino acids and worsens disease activity during colitis.

PubMed

DeLuca, Jennifer Aa; Allred, Kimberly F; Menon, Rani; Riordan, Rebekah; Weeks, Brad R; Jayaraman, Arul; Allred, Clinton D

2018-06-01

Inflammatory bowel disease is a complex collection of disorders. Microbial dysbiosis as well as exposure to toxins including xenoestrogens are thought to be risk factors for inflammatory bowel disease development and relapse. Bisphenol-A has been shown to exert estrogenic activity in the colon and alter intestinal function, but the role that xenoestrogens, such as bisphenol-A , play in colonic inflammation has been previously described but with conflicting results. We investigated the ability of bisphenol-A to exacerbate colonic inflammation and alter microbiota metabolites derived from aromatic amino acids in an acute dextran sulfate sodium-induced colitis model. Female C57BL/6 mice were ovariectomized and exposed to bisphenol-A daily for 15 days. Disease activity measures include body weight, fecal consistency, and rectal bleeding. Colons were scored for inflammation, injury, and nodularity. Alterations in the levels of microbiota metabolites derived from aromatic amino acids known to reflect phenotypic changes in the gut microbiome were analyzed. Bisphenol-A exposure increased mortality and worsened disease activity as well as inflammation and nodularity scores in the middle colon region following dextran sulfate sodium exposure. Unique patterns of metabolites were associated with bisphenol-A consumption. Regardless of dextran sulfate sodium treatment, bisphenol-A reduced levels of tryptophan and several metabolites associated with decreased inflammation in the colon. This is the first study to show that bisphenol-A treatment alone can reduce microbiota metabolites derived from aromatic amino acids in the colon which may be associated with increased colonic inflammation and inflammatory bowel disease. Impact statement As rates of inflammatory bowel disease rise, discovery of the mechanisms related to the development of these conditions is important. Environmental exposure is hypothesized to play a role in etiology of the disease, as are alterations in the gut microbiome and the metabolites they produce. This study is the first to show that bisphenol-A alone alters tryptophan and microbiota metabolites derived from aromatic amino acids in a manner consistent with autoimmune diseases, specifically inflammatory bowel diseases, regardless of dextran sulfate sodium treatment. These findings indicate a potential mechanism by which bisphenol-A negatively affects gut physiology to exacerbate inflammation.

Enzymes involved in a novel anaerobic cyclohexane carboxylic acid degradation pathway.

PubMed

Kung, Johannes W; Meier, Anne-Katrin; Mergelsberg, Mario; Boll, Matthias

2014-10-01

The anaerobic degradation of cyclohexane carboxylic acid (CHC) has so far been studied only in Rhodopseudomonas palustris, in which CHC is activated to cyclohexanoyl coenzyme A (cyclohexanoyl-CoA [CHCoA]) and then dehydrogenated to cyclohex-1-ene-1-carboxyl-CoA (CHeneCoA). This intermediate is further degraded by reactions of the R. palustris-specific benzoyl-CoA degradation pathway of aromatic compounds. However, CHeneCoA is not an intermediate in the degradation of aromatic compounds in all other known anaerobic bacteria; consequently, degradation of CHC was mostly unknown in anaerobic bacteria. We identified a previously unknown CHC degradation pathway in the Fe(III)-reducing Geobacter metallireducens by determining the following CHC-induced in vitro activities: (i) the activation of CHC to CHCoA by a succinyl-CoA:CHC CoA transferase, (ii) the 1,2-dehydrogenation of CHCoA to CHeneCoA by CHCoA dehydrogenase, and (iii) the unusual 1,4-dehydrogenation of CHeneCoA to cyclohex-1,5-diene-1-carboxyl-CoA. This last represents a previously unknown joint intermediate of the CHC and aromatic compound degradation pathway in bacteria other than R. palustris. The enzymes catalyzing the three reactions were purified and characterized as specific enzymes after heterologous expression of the encoding genes. Quantitative reverse transcription-PCR revealed that expression of these genes was highly induced during growth with CHC but not with benzoate. The newly identified CHC degradation pathway is suggested to be present in nearly all CHC-degrading anaerobic bacteria, including denitrifying, Fe(III)-reducing, sulfate-reducing, and fermenting bacteria. Remarkably, all three CHC degradation pathways always link CHC catabolism to the catabolic pathways of aromatic compounds. We propose that the capacity to use CHC as a carbon source evolved from already-existing aromatic compound degradation pathways. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

Enzymes Involved in a Novel Anaerobic Cyclohexane Carboxylic Acid Degradation Pathway

PubMed Central

Kung, Johannes W.; Meier, Anne-Katrin; Mergelsberg, Mario

2014-01-01

The anaerobic degradation of cyclohexane carboxylic acid (CHC) has so far been studied only in Rhodopseudomonas palustris, in which CHC is activated to cyclohexanoyl coenzyme A (cyclohexanoyl-CoA [CHCoA]) and then dehydrogenated to cyclohex-1-ene-1-carboxyl-CoA (CHeneCoA). This intermediate is further degraded by reactions of the R. palustris-specific benzoyl-CoA degradation pathway of aromatic compounds. However, CHeneCoA is not an intermediate in the degradation of aromatic compounds in all other known anaerobic bacteria; consequently, degradation of CHC was mostly unknown in anaerobic bacteria. We identified a previously unknown CHC degradation pathway in the Fe(III)-reducing Geobacter metallireducens by determining the following CHC-induced in vitro activities: (i) the activation of CHC to CHCoA by a succinyl-CoA:CHC CoA transferase, (ii) the 1,2-dehydrogenation of CHCoA to CHeneCoA by CHCoA dehydrogenase, and (iii) the unusual 1,4-dehydrogenation of CHeneCoA to cyclohex-1,5-diene-1-carboxyl-CoA. This last represents a previously unknown joint intermediate of the CHC and aromatic compound degradation pathway in bacteria other than R. palustris. The enzymes catalyzing the three reactions were purified and characterized as specific enzymes after heterologous expression of the encoding genes. Quantitative reverse transcription-PCR revealed that expression of these genes was highly induced during growth with CHC but not with benzoate. The newly identified CHC degradation pathway is suggested to be present in nearly all CHC-degrading anaerobic bacteria, including denitrifying, Fe(III)-reducing, sulfate-reducing, and fermenting bacteria. Remarkably, all three CHC degradation pathways always link CHC catabolism to the catabolic pathways of aromatic compounds. We propose that the capacity to use CHC as a carbon source evolved from already-existing aromatic compound degradation pathways. PMID:25112478

Oxidation of Naphthenoaromatic and Methyl-Substituted Aromatic Compounds by Naphthalene 1,2-Dioxygenase

PubMed Central

Selifonov, S. A.; Grifoll, M.; Eaton, R. W.; Chapman, P. J.

1996-01-01

Oxidation of acenaphthene, acenaphthylene, and fluorene was examined with recombinant strain Pseudomonas aeruginosa PAO1(pRE695) expressing naphthalene dioxygenase genes cloned from plasmid NAH7. Acenaphthene underwent monooxygenation to 1-acenaphthenol with subsequent conversion to 1-acenaphthenone and cis- and trans-acenaphthene-1,2-diols, while acenaphthylene was dioxygenated to give cis-acenaphthene-1,2-diol. Nonspecific dehydrogenase activities present in the host strain led to the conversion of both of the acenaphthene-1,2-diols to 1,2-acenaphthoquinone. The latter was oxidized spontaneously to naphthalene-1,8-dicarboxylic acid. No aromatic ring dioxygenation products were detected from acenaphthene and acenaphthylene. Mixed monooxygenase and dioxygenase actions of naphthalene dioxygenase on fluorene yielded products of benzylic 9-monooxygenation, aromatic ring dioxygenation, or both. The action of naphthalene dioxygenase on a variety of methyl-substituted aromatic compounds, including 1,2,4-trimethylbenzene and isomers of dimethylnaphthalene, resulted in the formation of benzylic alcohols, i.e., methyl group monooxygenation products, which were subsequently converted to the corresponding carboxylic acids by dehydrogenase(s) in the host strain. Benzylic monooxygenation of methyl groups was strongly predominant over aromatic ring dioxygenation and essentially nonspecific with respect to the substitution pattern of the aromatic substrates. In addition to monooxygenating benzylic methyl and methylene groups, naphthalene dioxygenase behaved as a sulfoxygenase, catalyzing monooxygenation of the sulfur heteroatom of 3-methylbenzothiophene. PMID:16535238

Sequence-specific 1H-NMR assignments for the aromatic region of several biologically active, monomeric insulins including native human insulin.

PubMed

Roy, M; Lee, R W; Kaarsholm, N C; Thøgersen, H; Brange, J; Dunn, M F

1990-06-12

The aromatic region of the 1H-FT-NMR spectrum of the biologically fully-potent, monomeric human insulin mutant, B9 Ser----Asp, B27 Thr----Glu has been investigated in D2O. At 1 to 5 mM concentrations, this mutant insulin is monomeric above pH 7.5. Coupling and amino acid classification of all aromatic signals is established via a combination of homonuclear one- and two-dimensional methods, including COSY, multiple quantum filters, selective spin decoupling and pH titrations. By comparisons with other insulin mutants and with chemically modified native insulins, all resonances in the aromatic region are given sequence-specific assignments without any reliance on the various crystal structures reported for insulin. These comparisons also give the sequence-specific assignments of most of the aromatic resonances of the mutant insulins B16 Tyr----Glu, B27 Thr----Glu and B25 Phe----Asp and the chemically modified species des-(B23-B30) insulin and monoiodo-Tyr A14 insulin. Chemical dispersion of the assigned resonances, ring current perturbations and comparisons at high pH have made possible the assignment of the aromatic resonances of human insulin, and these studies indicate that the major structural features of the human insulin monomer (including those critical to biological function) are also present in the monomeric mutant.

Use of antioxidant enzymes of clam Ruditapes philippinarum as biomarker to polycyclic aromatic hydrocarbon pollution

NASA Astrophysics Data System (ADS)

Zhu, Lin; Tang, Xuexi; Wang, Ying; Sui, Yadong; Xiao, Hui

2016-03-01

The typical organic pollutant polycyclic aromatic hydrocarbon (PAH) anthracene was selected as a contaminant to investigate its effects on the activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) in the clam Ruditapes philippinarum. The results show that SOD, CAT and GSH-Px had diff erent induction and inhibition reactions to anthracene stress, and that three diff erent organs in R. philippinarum (visceral mass, muscle tissue and mantle) had diff erent sensitivities to anthracene stress. This study suggest that SOD activities of the visceral mass, CAT activitities of the mantle and the visceral mass, and GSH-Px activity of the muscle tissue could be used as sensitive indicators of anthracene stress in R. philippinarum.

Mutagenicity of aerosols from the oxidative thermal decomposition of rigid polyurethane foam.

PubMed

Zitting, A; Falck, K; Skyttä, E

1980-01-01

The aerosol fraction of the oxidative thermal decomposition products (700 degrees C) of rigid polyurethane foam was collected on glass fiber filters and fractionated into either-soluble neutral, acidic, and basic fractions and water-soluble compounds. The fractions showed mutagenic activity in a bacterial fluctuation test with Salmonella typhimurium TA98 or Escherichia coli CM891 as the tester strains. All the fractions induced mutations in both strains after metabolic activation with rat liver S-9 mix. The basic and the water-soluble fractions were mutagenic for S. typhimurium TA 98 even without activation. Thin-layer chromatography showed the presence of several primary aromatic amines in the aerosol. Polycyclic aromatic hydrocarbons were not detected by glass capillary gas chromatogaphy.

Inhibitors of calling behavior of Plodia interpunctella

PubMed Central

Hirashima, Akinori; Shigeta, Yoko; Eiraku, Tomohiko; Kuwano, Eiichi

2003-01-01

Some octopamine agonists were found to suppress the calling behavior of the stored product Indian meal moth, Plodia interpunctella. Compounds were screened using a calling behavior bioassay using female P. interpunctella. Four active derivatives, with inhibitory activity at the nanomolar range, were identified in order of decreasing activity: 2-(1-phenylethylamino)-2-oxazoline > 2-(2-ethyl,6-methylanilino)oxazolidine > 2-(2-methyl benzylamino)-2-thiazoline > 2-(2,6-diethylanilino)thiazolidine. Three-dimensional pharmacophore hypotheses were built from a set of 15 compounds. Among the ten common-featured models generated by the program Catalyst/HipHop, a hypothesis including a hydrogen-bond acceptor lipid, a hydrophobic aromatic and two hydrophobic aliphatic features was considered to be essential for inhibitory activity in the calling behavior. Active compounds mapped well onto all the hydrogen-bond acceptor lipid, hydrophobic aromatic and hydrophobic aliphatic features of the hypothesis. On the other hand, less active compounds were shown not to achieve the energetically favorable conformation that is found in the active molecules in order to fit the 3D common-feature pharmacophore models. The present studies demonstrate that inhibition of calling behavior is via an octopamine receptor. Abbreviation: AII 2-(arylimino)imidazolidine AIO 2-(arylimino)oxazolidine AIT 2-(arylimino)thiazolidine CBO 2-(4-chlorobenzylamino)-2-(4-phenyl)oxazoline CDM chlordimeform Confs number of conformers DIP 2-(2,6-diethylphenylimino)piperidine Features/Confs total number of features divided by the number of conformers (summed over the entire family of conformers) HBA hydrogen-bond acceptor HBAl hydrogen-bond acceptor lipid HBD hydrogen-bond donor Hp hydrophobic HpAl hydrophobic aliphatic HpAr hydrophobic aromatic mp melting point MTO 2-(3-methyl benzylthio)-2-oxazoline NI negative ionizable NIO 2-(1-naphthylimino)oxazolidine OA octopamine ODA 2-phenyl-5,6-dihydro-4H-1,3,4-oxadiazine ODO 2-phenyl-5,6-dihydro-4H-1,3,4-oxadiazine-5(6H)-one PBAN pheromone biosynthesis activating neuropeptide PEO 2-(1-phenylethylamino)-2-oxazoline PI positive ionizable PIT 1-(2,6-dimethylphenyl)imidazolidine-2-thione RA ring aromatic SBO 2-(substituted benzylamino)-2-oxazoline SBT 2-(substituted benzylamino)-2-thiazoline STO 2-(substituted benzylthio)-2-oxazoline ZETA (Z,E)-9,12-tetradecadienyl acetate PMID:15841221

Synthesis of Novel Aza-aromatic Curcuminoids with Improved Biological Activities towards Various Cancer Cell Lines.

PubMed

Theppawong, Atiruj; Van de Walle, Tim; Grootaert, Charlotte; Bultinck, Margot; Desmet, Tom; Van Camp, John; D'hooghe, Matthias

2018-05-01

Curcumin, a natural compound extracted from the rhizomes of Curcuma longa , displays pronounced anticancer properties but lacks good bioavailability and stability. In a previous study, we initiated structure modification of the curcumin scaffold by imination of the labile β-diketone moiety to produce novel β-enaminone derivatives. These compounds showed promising properties for elaborate follow-up studies. In this work, we focused on another class of nitrogen-containing curcuminoids with a similar objective: to address the bioavailability and stability issues and to improve the biological activity of curcumin. This paper thus reports on the synthesis of new pyridine-, indole-, and pyrrole-based curcumin analogues (aza-aromatic curcuminoids) and discusses their water solubility, antioxidant activity, and antiproliferative properties. In addition, multivariate statistics, including hierarchical clustering analysis and principal component analysis, were performed on a broad set of nitrogen-containing curcuminoids. Compared to their respective mother structures, that is, curcumin and bisdemethoxycurcumin, all compounds, and especially the pyridin-3-yl β-enaminone analogues, showed better water solubility profiles. Interestingly, the pyridine-, indole-, and pyrrole-based curcumin derivatives demonstrated improved biological effects in terms of mitochondrial activity impairment and protein content, in addition to comparable or decreased antioxidant properties. Overall, the biologically active N -alkyl β-enaminone aza-aromatic curcuminoids were shown to offer a desirable balance between good solubility and significant bioactivity.

Gene cloning and in vivo characterization of a dibenzothiophene dioxygenase from Xanthobacter polyaromaticivorans.

PubMed

Hirano, Shin-Ichi; Haruki, Mitsuru; Takano, Kazufumi; Imanaka, Tadayuki; Morikawa, Masaaki; Kanaya, Shigenori

2006-02-01

Xanthobacter polyaromaticivorans sp. nov. 127W is a bacterial strain that is capable of degrading a wide range of cyclic aromatic compounds such as dibenzothiophene, biphenyl, naphthalene, anthracene, and phenanthrene even under extremely low oxygen [dissolved oxygen (DO)< or = 0.2 ppm] conditions (Hirano et al., Biosci Biotechnol Biochem 68:557-564, 2004). A major protein fraction carrying dibenzothiophene degradation activity was purified. Based on its partial amino acid sequences, dbdCa gene encoding alpha subunit terminal oxygenase (DbdCa) and its flanking region were cloned and sequenced. A phylogenetic analysis based on the amino acid sequence demonstrates that DbdCa is a member of a terminal oxygenase component of group IV ring-hydroxylating dioxygenases for biphenyls and monocyclic aromatic hydrocarbons, rather than group III dioxygenases for polycyclic aromatic hydrocarbons. Gene disruption in dbdCa abolished almost of the degradation activity against biphenyl, dibenzothiophene, and anthracene. The gene disruption also impaired degradation activity of the strain under extremely low oxygen conditions (DO< or = 0.2 ppm). These results indicate that Dbd from 127W represents a group IV dioxygenase that is functional even under extremely low oxygen conditions.

Biodegradation of naphthenic acid surrogates by axenic cultures.

PubMed

Yue, Siqing; Ramsay, Bruce A; Ramsay, Juliana A

2015-07-01

This is the first study to report that bacteria from the genera Ochrobactrum, Brevundimonas and Bacillus can be isolated by growth on naphthenic acids (NAs) extracted from oil sands process water (OSPW). These pure cultures were screened for their ability to use a range of aliphatic, cyclic and aromatic NA surrogates in 96-well microtiter plates using water-soluble tetrazolium redox dyes (Biolog Redox Dye H) as the indicator of metabolic activity. Of the three cultures, Ochrobactrum showed most metabolic activity on the widest range of NA surrogates. Brevundomonas and especially Ochrobactrum had higher metabolic activity on polycyclic aromatic compounds than other classes of NA surrogates. Bacillus also oxidized a wide range of NA surrogates but not as well as Ochrobactrum. Using this method to characterize NA utilisation, one can identify which NAs or NA classes in OSPW are more readily degraded. Since aromatic NAs have been shown to have an estrogenic effect and polycyclic monoaromatic compounds have been suggested to pose the greatest environmental threat among the NAs, these bacterial genera may play an important role in detoxification of OSPW. Furthermore, this study demonstrates that bacteria belonging to the genera Ochrobactrum and Bacillus can also degrade surrogates of tricyclic NAs.

Theoretical study on stabilization mechanisms of nitrate esters using aromatic amines as stabilizers.

PubMed

Sun, Zhi-Dan; Fu, Xiao-Long; Yu, Hong-Jian; Fan, Xue-Zhong; Ju, Xue-Hai

2017-10-05

The propellants of nitrate esters can be stabilized by some aromatic amines practically. To probe the mechanism of this phenomenon, we performed DFT calculations on: (1) The decompositions of nitrate esters (with and without the catalysis of NO 2 ) and (2) the reaction between the stabilizers and the nitro dioxide (NO 2 is released during the storage of nitrate esters). The structures on the reaction paths (reactants, intermediates and products) were optimized at the (U)B3LYP/6-31G** level. It was shown that NO 2 lowers the activation energy barrier in the decomposition of nitrate ester by 11.82-17.86kJ/mol and efficiently catalyzes the rupture of ONO 2 bond. However, the aromatic amines, typical stabilizers for nitrate esters, can easily eliminate NO 2 with activation barriers as low as 27-113kJ/mol (with one exception of 128kJ/mol). These values are, for most cases, lower or much lower than the activation energy barriers for reactions between nitrate esters and NO 2 (127-137kJ/mol). Consequently, the stabilizers can block the NO 2 catalysis for the decompositions of nitrate esters. Copyright © 2017 Elsevier B.V. All rights reserved.

Graphene stabilized ultra-small CuNi nanocomposite with high activity and recyclability toward catalysing the reduction of aromatic nitro-compounds.

PubMed

Fang, Hao; Wen, Ming; Chen, Hanxing; Wu, Qingsheng; Li, Weiying

2016-01-07

Nowadays, it is of great significance and a challenge to design a noble-metal-free catalyst with high activity and a long lifetime for the reduction of aromatic nitro-compounds. Here, a 2D structured nanocomposite catalyst with graphene supported CuNi alloy nanoparticles (NPs) is prepared, and is promising for meeting the requirements of green chemistry. In this graphene/CuNi nanocomposite, the ultra-small CuNi nanoparticles (∼2 nm) are evenly anchored on graphene sheets, which is not only a breakthrough in the structures, but also brings about an outstanding performance in activity and stability. Combined with a precise optimization of the alloy ratios, the reaction rate constant of graphene/Cu61Ni39 reached a high level of 0.13685 s(-1), with a desirable selectivity as high as 99% for various aromatic nitro-compounds. What's more, the catalyst exhibited a unprecedented long lifetime because it could be recycled over 25 times without obvious performance decay or even a morphology change. This work showed the promise and great potential of noble-metal-free catalysts in green chemistry.

Dimethandrolone (7α,11β-dimethyl-19-nortestosterone) and 11β-methyl-19-nortestosterone are not converted to aromatic A-ring products in the presence of recombinant human aromatase☆

PubMed Central

Attardi, Barbara J.; Pham, Trung C.; Radler, Lisa M.; Burgenson, Janet; Hild, Sheri A.; Reel, Jerry R.

2008-01-01

Dimethandrolone undecanoate (DMAU: 7α,11β-dimethyl-19-nortestosterone 17β-undecanoate) is a potent orally active androgen in development for hormonal therapy in men. Cleavage of the 17β-ester bond by esterases in vivo leads to liberation of the biologically active androgen, dimethandrolone (DMA), a 19-norandrogen. For hormone replacement in men, administration of C19 androgens such as testosterone (T) may lead to elevations in circulating levels of estrogens due to aromatization. As several reports have suggested that certain 19-norandrogens may serve as substrates for the aromatase enzyme and are converted to the corresponding aromatic A-ring products, it was important to investigate whether DMA, the related compound, 11β-methyl-19-nortestosterone (11β-MNT), also being tested for hormonal therapy in men, and other 19-norandrogens can be converted to aromatic A-ring products by human aromatase. The hypothetical aromatic A-ring product corresponding to each substrate was obtained by chemical synthesis. These estrogens bound with high affinity to purified recombinant human estrogen receptors (ER) α and β in competitive binding assays (IC50's: 5−12 × 10−9 M) and stimulated transcription of 3XERE-luciferase in T47Dco human breast cancer cells with a potency equal to or greater than that of estradiol (E2) (EC50's: 10−12 to 10−11 M). C19 androgens (T, 17α-methyltestosterone (17α-MT), androstenedione (AD), and 16α-hydroxyandrostenedione (16α-OHAD)), 19-norandrogens (DMA, 11β-MNT, 19-nortestosterone (19-NT), and 7α-methyl-19-nortestosterone (MENT)) or the structurally similar 19-norprogestin, norethindrone (NET) were incubated at 50 μM with recombinant human aromatase for 10−180 min at 37 °C. The reactions were terminated by extraction with acetonitrile and centrifugation, and substrate and potential product were separated by HPLC. Retention times were monitored by UV absorption, and UV peaks were quantified using standard curves. Aromatization of the positive controls, T, AD, and 16α-OHAD was linear for 40−60 min, and conversion of T or AD was complete by 120 min. The nonsteroidal aromatase inhibitor, letrozole, demonstrated concentration-dependent suppression of T aromatization. Under the same conditions, there was no detectable conversion of DMA, 11β-MNT, or NET to their respective hypothetical aromatic A-ring products during incubation times up to 180 min. Aromatization of MENT and 19-NT proceeded slowly and was limited. Collectively, these data support the notion that in the absence of the C19-methyl group, which is the site of attack by oxygen, aromatization of androgenic substrates proceeds slowly or not at all and that this reaction is impeded by the presence of a methyl group at the 11β position. PMID:18555683

Combining molecular docking and QSAR studies for modeling the anti-tyrosinase activity of aromatic heterocycle thiosemicarbazone analogues

NASA Astrophysics Data System (ADS)

Dong, Huanhuan; Liu, Jing; Liu, Xiaoru; Yu, Yanying; Cao, Shuwen

2018-01-01

A collection of thirty-six aromatic heterocycle thiosemicarbazone analogues presented a broad span of anti-tyrosinase activities were designed and obtained. A robust and reliable two-dimensional quantitative structure-activity relationship model, as evidenced by the high q2 and r2 values (0.848 and 0.893, respectively), was gained based on the analogues to predict the quantitative chemical-biological relationship and the new modifier direction. Inhibitory activities of the compounds were found to greatly depend on molecular shape and orbital energy. Substituents brought out large ovality and high highest-occupied molecular orbital energy values helped to improve the activity of these analogues. The molecular docking results provided visual evidence for QSAR analysis and inhibition mechanism. Based on these, two novel tyrosinase inhibitors O04 and O05 with predicted IC50 of 0.5384 and 0.8752 nM were designed and suggested for further research.

Destruction and survival of polycyclic aromatic hydrocarbons in active galaxies

NASA Technical Reports Server (NTRS)

Voit, G. M.

1992-01-01

Infrared spectra of dusty galactic environments often contain emission features attributed to polycyclic aromatic hydrocarbons or PAHs, which can be considered to be very small grains or very large molecules. Although IR spectra of starburst galaxies almost always show these emission features, similar spectra of active galaxies are usually featureless. Even in those active galaxies that do exhibit PAH emission, the PAHs still appear to be eradicated from the nuclear region. This dichotomy suggests that PAHs are destroyed by the intense hard radiation field from an AGN. Laboratory experiments show that certain PAHs are, in fact, so effectively destroyed by individual EUV and X-ray photons that they cannot survive even at kiloparsec distances from active nuclei. Regions within active galaxies that do show PAH emission must therefore be shielded from the central X-ray source by a substantial column density of X-ray absorbing gas.

Adsorption of aromatic compounds from the biodegradation of azo dyes on activated carbon

NASA Astrophysics Data System (ADS)

Faria, P. C. C.; Órfão, J. J. M.; Figueiredo, J. L.; Pereira, M. F. R.

2008-03-01

The adsorption of three selected aromatic compounds (aniline, sulfanilic acid and benzenesulfonic acid) on activated carbons with different surface chemical properties was investigated at different solution pH. A fairly basic commercial activated carbon was modified by means of chemical treatment with HNO 3, yielding an acid activated carbon. The textural properties of this sample were not significantly changed after the oxidation treatment. Equilibrium isotherms of the selected compounds on the mentioned samples were obtained and the results were discussed in relation to their surface chemistry. The influence of electrostatic and dispersive interactions involved in the uptake of the compounds studied was evaluated. The Freundlich model was used to fit the experimental data. Higher uptakes are attained when the compounds are present in their molecular form. In general, adsorption was disfavoured by the introduction of oxygen-containing groups on the surface of the activated carbon.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Keeratitham, Waralee, E-mail: waralee.ke@student.chula.ac.th; Somwangthanaroj, Anongnat, E-mail: anongnat.s@chula.ac.th

Herein, our main objective is to prepare the fast curing epoxy system with high glass transition temperature (T{sub g}) by incorporating the multifunctional epoxy resin into the mixture of diglycidyl ether of bisphenol A (DGEBA) as a major epoxy component and aromatic diamine as a hardener. Furthermore, the curing behavior as well as thermal and thermomechanical properties were investigated by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA) and thermomechanical analysis (TMA). It was found that T{sub g} obtained from tan δ of DGEBA/aromatic diamine system increased from 100 °C to 205 °C with the presence of 30 percentage bymore » weight of multifunctional epoxy resin. Additionally, the isothermal DSC results showed that the multifunctional epoxy resin can accelerate the curing reaction of DGEBA/aromatic diamine system. Namely, a high degree of curing (∼90%) was achieved after a few minutes of curing at low temperature of 130 °C, owing to a large number of epoxy ring of multifunctional epoxy resin towards the active hydrogen atoms of aromatic diamine.« less

QSAR Study for Carcinogenic Potency of Aromatic Amines Based on GEP and MLPs

PubMed Central

Song, Fucheng; Zhang, Anling; Liang, Hui; Cui, Lianhua; Li, Wenlian; Si, Hongzong; Duan, Yunbo; Zhai, Honglin

2016-01-01

A new analysis strategy was used to classify the carcinogenicity of aromatic amines. The physical-chemical parameters are closely related to the carcinogenicity of compounds. Quantitative structure activity relationship (QSAR) is a method of predicting the carcinogenicity of aromatic amine, which can reveal the relationship between carcinogenicity and physical-chemical parameters. This study accessed gene expression programming by APS software, the multilayer perceptrons by Weka software to predict the carcinogenicity of aromatic amines, respectively. All these methods relied on molecular descriptors calculated by CODESSA software and eight molecular descriptors were selected to build function equations. As a remarkable result, the accuracy of gene expression programming in training and test sets are 0.92 and 0.82, the accuracy of multilayer perceptrons in training and test sets are 0.84 and 0.74 respectively. The precision of the gene expression programming is obviously superior to multilayer perceptrons both in training set and test set. The QSAR application in the identification of carcinogenic compounds is a high efficiency method. PMID:27854309

Seawater Polluted with Highly Concentrated Polycyclic Aromatic Hydrocarbons Suppresses Osteoblastic Activity in the Scales of Goldfish, Carassius auratus.

PubMed

Suzuki, Nobuo; Sato, Masayuki; Nassar, Hossam F; Abdel-Gawad, Fagr Kh; Bassem, Samah M; Yachiguchi, Koji; Tabuchi, Yoshiaki; Endo, Masato; Sekiguchi, Toshio; Urata, Makoto; Hattori, Atsuhiko; Mishima, Hiroyuki; Shimasaki, Youhei; Oshima, Yuji; Hong, Chun-Sang; Makino, Fumiya; Tang, Ning; Toriba, Akira; Hayakawa, Kazuichi

2016-08-01

We have developed an original in vitro bioassay using teleost scale, that has osteoclasts, osteoblasts, and bone matrix as each marker: alkaline phosphatase (ALP) for osteoblasts and tartrate-resistant acid phosphatase (TRAP) for osteoclasts. Using this scale in vitro bioassay, we examined the effects of seawater polluted with highly concentrated polycyclic aromatic hydrocarbons (PAHs) and nitro-polycyclic aromatic hydrocarbons (NPAHs) on osteoblastic and osteoclastic activities in the present study. Polluted seawater was collected from two sites (the Alexandria site on the Mediterranean Sea and the Suez Canal site on the Red Sea). Total levels of PAHs in the seawater from the Alexandria and Suez Canal sites were 1364.59 and 992.56 ng/l, respectively. We were able to detect NPAHs in both seawater samples. Total levels of NPAHs were detected in the seawater of the Alexandria site (12.749 ng/l) and the Suez Canal site (3.914 ng/l). Each sample of polluted seawater was added to culture medium at dilution rates of 50, 100, and 500, and incubated with the goldfish scales for 6 hrs. Thereafter, ALP and TRAP activities were measured. ALP activity was significantly suppressed by both polluted seawater samples diluted at least 500 times, but TRAP activity did not change. In addition, mRNA expressions of osteoblastic markers (ALP, osteocalcin, and the receptor activator of the NF-κB ligand) decreased significantly, as did the ALP enzyme activity. In fact, ALP activity decreased on treatment with PAHs and NPAHs. We conclude that seawater polluted with highly concentrated PAHs and NPAHs influences bone metabolism in teleosts.

Mild Aromatic Palladium-Catalyzed Protodecarboxylation: Kinetic Assessment of the Decarboxylative Palladation and the Protodepalladation Steps

PubMed Central

Dickstein, Joshua S.; Curto, John M.; Gutierrez, Osvaldo; Mulrooney, Carol A.; Kozlowski, Marisa C.

2013-01-01

Mechanism studies of a mild palladium catalyzed decarboxylation of aromatic carboxylic acids are described. In particular, reaction orders and activation parameters for the two stages of the transformation were determined. These studies guided development of a catalytic system capable of turnover. Further evidence reinforces that the second stage, protonation of the aryl palladium intermediate, is the rate-determining step of the reaction. The first step, decarboxylative palladation is proposed to occur through an intramolecular electrophilic palladation pathway, which is supported by computational and mechansim studies. In contrast to the reverse reaction (C-H insertion), the data support an electrophilic aromatic substitution mechanism involving a stepwise intramolecular protonation sequence for the protodepalladation portion of the reaction. PMID:23590518

Phenol abatement using persulfate activated by nZVI, H2O2 and NaOH and development of a kinetic model for alkaline activation.

PubMed

Lominchar, Miguel A; Rodríguez, Sergio; Lorenzo, David; Santos, Noelia; Romero, Arturo; Santos, Aurora

2018-01-01

Three persulfate (PS) activation methods (nanoparticles of zero-valent iron (nZVI), hydrogen peroxide and alkali) were compared using phenol as target pollutant. Firstly, four experiments were conducted at 25°C in a batch way using the same initial phenol and oxidant concentrations (10 mM and 420 mM, respectively), being the molar ratio activator/PS fixed to 0.005 with nZVI (mass ratio 0.0011 nZVI/PS), to 2 using hydrogen peroxide and to 2 and 4 with NaOH. Phenol and PS conversions and aromatic byproducts profiles during 168 h reaction time were measured and compared, as well as mineralization and ecotoxicity of the samples. It was found that both phenol and aromatic byproducts (catechol and hydroquinone) totally disappeared using PS activated by alkali before 24 h, while a significant amount of aromatic intermediates was obtained with nZVI and H 2 O 2 . Additional runs were carried out using shorter times (0-2 h) to discriminate the oxidation route and the kinetic model of phenol abatement by using PS activated by alkali. Different initial concentrations of phenol (5-15 mM), PS (210 and 420 mM) and molar ratio NaOH/PS (2 and 4) were employed. The kinetic model obtained predicts accurately the evolution of phenol, persulfate, hydroquinone and catechol.

Purification and characteristics of an inducible by polycyclic aromatic hydrocarbons NADP(+)-dependent naphthalenediol dehydrogenase (NDD) in Mucor circinelloides YR-1.

PubMed

Camacho-Morales, Reyna Lucero; Zazueta-Novoa, Vanesa; Casillas, Juana Lizbeth González; Ballesteros, Elizabeth Aranda; Bote, Juan Antonio Ocampo; Zazueta-Sandoval, Roberto

2014-05-01

We detected NADP(+)-dependent dihydrodiol dehydrogenase (DD) activity in a cell-free extract from Mucor circinelloides YR-1, after high-speed centrifugation. We analyzed the enzymatic activity in the cytosolic fraction by zymograms, as described previously, and eight different DD activity bands were revealed. Five constitutive DD activities (DD1-5) were present when glucose was used as carbon source and three inducible activities (NDD, PDD1 and PDD2) when aromatic hydrocarbon compounds were used. NDD activity was induced all of the aromatic hydrocarbon compounds. The highest DD activity inducer was naphthalene and the lowest was pyrene. One of the enzymes showed higher activity with cis-naphthalene-diol rather than with trans-nahthalenediol as a substrate. We purified this particular enzyme to homogeneity and found that it had an isoelectric point of 4.6. The molecular weight for the native protein was 197.4kDa and 49.03±0.5kDa for the monomer that conforms it, suggesting a homotetrameric structure for the complete enzyme. Polyclonal antibodies were raised against it and obtained. NDD activity was almost totally inhibited when antibodies were used at low concentrations, and in native immunoblots only one band, which corresponds to the activity band detected in the zymograms, could be detected. In denaturing PAGE immunoblots only one band was detected. This band corresponds to the purified protein band of 49kDa detected in SDS-PAGE gels. The other two inducible enzymes PDD1 and PDD2 were present only when phenanthrene was used as sole carbon source in the culture media. Copyright © 2014 Elsevier Inc. All rights reserved.

Effect of systemic herbicides on N2-fixing and phosphate solubilizing microorganisms in relation to availability of nitrogen and phosphorus in paddy soils of West Bengal.

PubMed

Das, Amal Chandra; Debnath, Anjan

2006-11-01

A field experiment has been conducted with four systemic herbicides viz., butachlor [N-(butoxymethyl)-2-chloro-2',6'-diethyl-acetanilide], fluchloralin [N-(2-chloroethyl)-(2,6-dinitro-N-propyl-4-trifluoromethyl) aniline], oxadiazon [5-terbutyl-3-(2,4-dichloro-5-isopro poxyphenyl)-1,3,4-oxadiazol-2-one] and oxyfluorfen [2-chloro-1-(3-ethoxy-4-nitrophenyl)-4-(trifluoromethyl) benzene] at their recommended field rates (2.0, 1.5, 0.4 and 0.12kga.i.ha(-1), respectively) to investigate their effects on growth and activities of aerobic non-symbiotic N(2)-fixing bacteria and phosphate solubilizing microorganisms in relation to availability of nitrogen and phosphorus in the rhizosphere soils as well as yield of the rice crop (Oryza sativa L cv. IR-36). Application of herbicides, in general, highly stimulated the population and activities of the target microorganisms, which resulted in a greater amount of atmospheric nitrogen fixation and phosphate solubilization in the rhizosphere soils of the test crop. The greater microbial activities subsequently augmented the mineralization and availability of nitrogen and phosphorus in the soil solution, which in turn increased the yield of the crop. Among the herbicides, oxyfluorfen was most stimulative followed by fluchloralin and oxadiazon in augmenting the microbial activities in soil. Butachlor also accentuated the mineralization and availability of nitrogen due to higher incitement of non-symbiotic N(2)-fixing bacteria in paddy soil. The grain and straw yields of the crop were also significantly increased due to the application of oxyfluorfen (20.2% and 21%) followed by fluchloralin (13.1% and 15.4%) and butachlor (9.1% and 10.2%), respectively.

Expedited Synthesis of Fluorine-18 Labeled Phenols. A Missing Link in PET Radiochemistry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Katzenellenbogen, John A.; Zhou, Dong

Fluorine-18 (F-18) is arguably the most valuable radionuclide for positron emission tomographic (PET) imaging. However, while there are many methods for labeling small molecules with F-18 at aliphatic positions and on electron-deficient aromatic rings, there are essentially no reliable and practical methods to label electron-rich aromatic rings such as phenols, with F-18 at high specific activity. This is disappointing because fluorine-labeled phenols are found in many drugs; there are also many interesting plant metabolites and hormones that contain either phenols or other electron-rich aromatic systems such as indoles whose metabolism, transport, and distribution would be interesting to study if theymore » could readily be labeled with F-18. Most approaches to label phenols with F-18 involve the labeling of electron-poor precursor arenes by nucleophilic aromatic substitution, followed by subsequent conversion to phenols by oxidation or other multi-step sequences that are often inefficient and time consuming. Thus, the lack of good methods for labeling phenols and other electron-rich aromatics with F-18 at high specific activity represents a significant methodological gap in F-18 radiochemistry that can be considered a “Missing Link in PET Radiochemistry”. The objective of this research project was to develop and optimize a series of unusual synthetic transformations that will enable phenols (and other electron-rich aromatic systems) to be labeled with F-18 at high specific activity, rapidly, reliably, and conveniently, thereby bridging this gap. Through the studies conducted with support of this project, we have substantially advanced synthetic methodology for the preparation of fluorophenols. Our progress is presented in detail in the sections below, and much has been published or presented publication; other components are being prepared for publication. In essence, we have developed a completely new method to prepare o-fluorophenols from non-aromatic precursors (diazocyclohexenones) by a novel reaction sequence that uses fluoride ion as a precursor and various activating electrophiles, and we have improved methods for the preparation of heterodiaryl iodonium salts. Both methods have been used to prepare interesting potential radiotracers. Other advances have been made in labeling dendrimeric nanoparticle structures of increasing interest for multimodal imaging and in advancing labeling through fluorosilane bonds. Thus, the progress we have made substantially fills the significant gap in PET radiochemistry that we originally identified, and it provides for the field new methodology that can be applied to a number of current challenges, including the preparation of several molecules of interest as radiotracers, such as 2-[18F]Fluoroestradiol (2-FES) and m-fluorotyrosine, which we have illustrated. These methods can be used by any skilled radiochemist interesting in preparing these agents or similar fluorine-18 labeled electron-rich arene systems of interested for PET biological imaging in the most general sense.« less

Role of Aromatic Amino Acids in Lipopolysaccharide and Membrane Interactions of Antimicrobial Peptides for Use in Plant Disease Control*

PubMed Central

Datta, Aritreyee; Bhattacharyya, Dipita; Singh, Shalini; Ghosh, Anirban; Schmidtchen, Artur; Malmsten, Martin; Bhunia, Anirban

2016-01-01

KYE28 (KYEITTIHNLFRKLTHRLFRRNFGYT-LR), the representative sequence of helix D of heparin co-factor II, was demonstrated to be potent against agronomically important Gram-negative plant pathogens Xanthomonas vesicatoria and Xanthomonas oryzae, capable of inhibiting disease symptoms in detached tomato leaves. NMR studies in the presence of lipopolysaccharide provided structural insights into the mechanisms underlying this, notably in relationship to outer membrane permeabilization. The three-dimensional solution structure of KYE28 in LPS is characterized by an N-terminal helical segment, an intermediate loop followed by another short helical stretch, and an extended C terminus. The two termini are in close proximity to each other via aromatic packing interactions, whereas the positively charged residues form an exterior polar shell. To further demonstrate the importance of the aromatic residues for this, a mutant peptide KYE28A, with Ala substitutions at Phe11, Phe19, Phe23, and Tyr25 was designed, which showed attenuated antimicrobial activity at high salt concentrations, as well as lower membrane disruption and LPS binding abilities compared with KYE28. In contrast to KYE28, KYE28A adopted an extended helical structure in LPS with extended N and C termini. Aromatic packing interactions were completely lost, although hydrophobic interaction between the side chains of hydrophobic residues were still partly retained, imparting an amphipathic character and explaining its residual antimicrobial activity and LPS binding as observed from ellipsometry and isothermal titration calorimetry. We thus present key structural aspects of KYE28, constituting an aromatic zipper, of potential importance for the development of novel plant protection agents and therapeutic agents. PMID:27137928

Solvent-resistant sol-gel polydimethyldiphenylsiloxane coating for on-line hyphenation of capillary microextraction with high-performance liquid chromatography.

PubMed

Segro, Scott S; Malik, Abdul

2008-09-26

A sol-gel polydimethyldiphenylsiloxane (PDMDPS) coating was developed for capillary microextraction on-line hyphenated with high-performance liquid chromatography (HPLC). This coating was created using methyltrimethoxysilane (MTMS) as the sol-gel precursor and di-hydroxy-terminated PDMDPS as the sol-gel active polymer. The methyl and phenyl groups on the sol-gel active polymer and the methyl groups on the sol-gel precursor ultimately turned into pendant groups providing the ability to extract non-polar analytes. A 40-cm segment of 0.25 mm I.D. fused silica capillary containing the sol-gel PDMDPS coating was installed as an external sampling loop in an HPLC injection port. Aqueous samples containing polycyclic aromatic hydrocarbons (PAHs), aromatic compounds, ketones, and aldehydes were passed through this capillary wherein the analytes were extracted by the sol-gel coating. The extracted analytes were then transferred to the HPLC column using isocratic or gradient elution with an acetonitrile/water mobile phase. This capillary demonstrated excellent extraction capability for non-polar (e.g., polycyclic aromatic hydrocarbons and aromatic compounds) as well as moderately polar compounds, such as aromatic amines, ketones, and aldehydes. The test results indicate that PDMDPS can be successfully immobilized into a sol-gel network and that the resulting solvent-resistant sol-gel organic-inorganic hybrid coating can be effectively used for on-line hyphenation of capillary microextraction with high-performance liquid chromatography. The test results also indicate that the sol-gel PDMDPS coated capillary is resistant to high-temperature solvents, making it suitable for applications in high-temperature HPLC. To the best of our knowledge, this is the first report on the creation of a silica-based sol-gel PDMDPS coating used in capillary microextraction on-line hyphenated to HPLC.

Removal of Intermediate Aromatic Halogenated DBPs by Activated Carbon Adsorption: A New Approach to Controlling Halogenated DBPs in Chlorinated Drinking Water.

PubMed

Jiang, Jingyi; Zhang, Xiangru; Zhu, Xiaohu; Li, Yu

2017-03-21

During chlorine disinfection of drinking water, chlorine may react with natural organic matter (NOM) and bromide ion in raw water to generate halogenated disinfection byproducts (DBPs). To mitigate adverse effects from DBP exposure, granular activated carbon (GAC) adsorption has been considered as one of the best available technologies for removing NOM (DBP precursor) in drinking water treatment. Recently, we have found that many aromatic halogenated DBPs form in chlorination, and they act as intermediate DBPs to decompose and form commonly known DBPs including trihalomethanes and haloacetic acids. In this work, we proposed a new approach to controlling drinking water halogenated DBPs by GAC adsorption of intermediate aromatic halogenated DBPs during chlorination, rather than by GAC adsorption of NOM prior to chlorination (i.e., traditional approach). Rapid small-scale column tests were used to simulate GAC adsorption in the new and traditional approaches. Significant reductions of aromatic halogenated DBPs were observed in the effluents with the new approach; the removals of total organic halogen, trihalomethanes, and haloacetic acids by the new approach always exceeded those by the traditional approach; and the effluents with the new approach were considerably less developmentally toxic than those with the traditional approach. Our findings indicate that the new approach is substantially more effective in controlling halogenated DBPs than the traditional approach.

Response of humic-reducing microorganisms to the redox properties of humic substance during composting.

PubMed

Zhao, Xinyu; He, Xiaosong; Xi, Beidou; Gao, Rutai; Tan, Wenbing; Zhang, Hui; Huang, Caihong; Li, Dan; Li, Meng

2017-12-01

Humic substance (HS) could be utilized by humus-reducing microorganisms (HRMs) as the terminal acceptors. Meanwhile, the reduction of HS can support the microbial growth. This process would greatly affect the redox conversion of inorganic and organic pollutants. However, whether the redox properties of HS lined with HRMs community during composting still remain unclear. This study aimed to assess the relationships between the redox capability of HS [i.e. humic acids (HA) and fulvic acids (FA)] and HRMs during composting. The results showed that the changing patterns of electron accepting capacity and electron donating capacity of HS were diverse during seven composting. Electron transfer capacities (ETC) of HA was significantly correlated with the functional groups (i.e. alkyl C, O-alkyl C, aryl C, carboxylic C, aromatic C), aromaticity and molecular weight of HA. Aromatic C, phenols, aryl C, carboxylic C, aromaticity and molecular weight of HS were the main structuralfeatures associated with the ETC of FA. Ten key genera of HRMs were found significantly determine these redox-active functional groups of HS during composting, thus influencing the ETC of HS in composts. In addition, a regulating method was suggested to enhance the ETC of HS during composting based on the relationships between the key HRMs and redox-active functional groups as well as environmental variables. Copyright © 2017 Elsevier Ltd. All rights reserved.

NIOSH Manual of Analytical Methods (third edition). Fourth supplement

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1990-08-15

The NIOSH Manual of Analytical Methods, 3rd edition, was updated for the following chemicals: allyl-glycidyl-ether, 2-aminopyridine, aspartame, bromine, chlorine, n-butylamine, n-butyl-glycidyl-ether, carbon-dioxide, carbon-monoxide, chlorinated-camphene, chloroacetaldehyde, p-chlorophenol, crotonaldehyde, 1,1-dimethylhydrazine, dinitro-o-cresol, ethyl-acetate, ethyl-formate, ethylenimine, sodium-fluoride, hydrogen-fluoride, cryolite, sodium-hexafluoroaluminate, formic-acid, hexachlorobutadiene, hydrogen-cyanide, hydrogen-sulfide, isopropyl-acetate, isopropyl-ether, isopropyl-glycidyl-ether, lead, lead-oxide, maleic-anhydride, methyl-acetate, methyl-acrylate, methyl-tert-butyl ether, methyl-cellosolve-acetate, methylcyclohexanol, 4,4'-methylenedianiline, monomethylaniline, monomethylhydrazine, nitric-oxide, p-nitroaniline, phenyl-ether, phenyl-ether-biphenyl mixture, phenyl-glycidyl-ether, phenylhydrazine, phosphine, ronnel, sulfuryl-fluoride, talc, tributyl-phosphate, 1,1,2-trichloro-1,2,2-trifluoroethane, trimellitic-anhydride, triorthocresyl-phosphate, triphenyl-phosphate, and vinyl-acetate.

Facile on-site detection of substituted aromatic pollutants in water using thin layer chromatography combined with surface-enhanced Raman spectroscopy.

PubMed

Li, Dawei; Qu, Lulu; Zhai, Wenlei; Xue, Jinqun; Fossey, John S; Long, Yitao

2011-05-01

A novel facile method for on-site detection of substituted aromatic pollutants in water using thin layer chromatography (TLC) combined with surface-enhanced Raman spectroscopy (SERS) was explored. Various substituted aromatics in polluted water were separated by a convenient TLC protocol and then detected using a portable Raman spectrometer with the prepared silver colloids serving as SERS-active substrates. The effects of operating conditions on detection efficacy were evaluated, and the application of TLC-SERS to on-site detection of artificial and real-life samples of aromatics/polluted water was systematically investigated. It was shown that commercially available Si 60-F(254) TLC plates were suitable for separation and displayed low SERS background and good separation efficiency, 2 mM silver colloids, 20 mM NaCl (working as aggregating agent), 40 mW laser power, and 50 s intergration time were appropriate for the detection regime. Furthermore, qualitative and quantitative detection of most of substituted aromatic pollutants was found to be readily accomplished using the developed TLC-SERS technique, which compared well with GC-MS in terms of identification ability and detection accuracy, and a limit of detection (LOD) less than 0.2 ppm (even at ppb level for some analytes) could be achieved under optimal conditions. The results reveal that the presented convenient method could be used for the effective separation and detection of the substituted aromatic pollutants of water on site, thus reducing possible influences of sample transportation and contamination while shortening the overall analysis time for emergency and routine monitoring of the substituted aromatics/polluted water.

Metabolism and Biomarkers of Heterocyclic Aromatic Amines in Molecular Epidemiology Studies: Lessons Learned from Aromatic Amines

PubMed Central

2011-01-01

Aromatic amines and heterocyclic aromatic amines (HAAs) are structurally related classes of carcinogens that are formed during the combustion of tobacco or during the high-temperature cooking of meats. Both classes of procarcinogens undergo metabolic activation by N-hydroxylation of the exocyclic amine group, to produce a common proposed intermediate, the arylnitrenium ion, which is the critical metabolite implicated in toxicity and DNA damage. However, the biochemistry and chemical properties of these compounds are distinct and different biomarkers of aromatic amines and HAAs have been developed for human biomonitoring studies. Hemoglobin adducts have been extensively used as biomarkers to monitor occupational and environmental exposures to a number of aromatic amines; however, HAAs do not form hemoglobin adducts at appreciable levels and other biomarkers have been sought. A number of epidemiologic studies that have investigated dietary consumption of well-done meat in relation to various tumor sites reported a positive association between cancer risk and well-done meat consumption, although some studies have shown no associations between well-done meat and cancer risk. A major limiting factor in most epidemiological studies is the uncertainty in quantitative estimates of chronic exposure to HAAs and, thus, the association of HAAs formed in cooked meat and cancer risk has been difficult to establish. There is a critical need to establish long-term biomarkers of HAAs that can be implemented in molecular epidemioIogy studies. In this review article, we highlight and contrast the biochemistry of several prototypical carcinogenic aromatic amines and HAAs to which humans are chronically exposed. The biochemical properties and the impact of polymorphisms of the major xenobiotic-metabolizing enzymes on the biological effects of these chemicals are examined. Lastly, the analytical approaches that have been successfully employed to biomonitor aromatic amines and HAAs, and emerging biomarkers of HAAs that may be implemented in molecular epidemiology studies are discussed. PMID:21688801

Use of Torulaspora delbrueckii Co-fermentation With Two Saccharomyces cerevisiae Strains With Different Aromatic Characteristic to Improve the Diversity of Red Wine Aroma Profile

PubMed Central

Zhang, Bo-Qin; Luan, Yu; Duan, Chang-Qing; Yan, Guo-Liang

2018-01-01

The use of selected Saccharomyces and non-Saccharomyces strains as mixed starters has advantages over pure fermentation due to achieving wine products with distinctive and diversified aroma expected by consumers. To obtain a way to improve the aroma diversity and increase the differentiation of wine product, in this study, the aromatic effect of multi-culture of indigenous Torulaspora delbrueckii (TD12), simultaneous and sequential inoculation with two Saccharomyces strains (indigenous icewine yeast SC45 and commercial yeast BDX) with different enological characteristics were investigated in laboratory-scale 20 L fermenter, respectively. The results showed that T. delbrueckii co-fermented with different S. cerevisiae strain could generate diversified physicochemical and aromatic quality of wine as evidenced by PCA. Mixed fermentation of SC45/TD12 produced higher contents of higher alcohol (3-methyl-1-pentanol and phenylethyl alcohol), ethyl esters (ethyl decanoate and ethyl butanoate), terpenes and phenylacetaldehyde with less fatty acids (hexanoic acid, octanoic acid) and acetic acid, while BDX/TD12 generated more C6 alcohol (1-hexanol) and acetate esters (ethyl acetate and isoamyl acetate). Compared to simultaneous inoculation, sequential inoculation could achieve higher aroma diversity, and generate higher intensity of fruity, flowery and sweet attributes of wine as assessed by calculating the odor activity values. The different S. cerevisiae strain and inoculation method in alcoholic fermentation could further influence the formations of aromatic compounds in malolactic fermentation. Our results highlighted the importance of S. cerevisiae strain in shaping the aromatic quality of wine in mixed fermentation, and also suggested that using different S. cerevisiae strains with distinct aromatic characteristics co-fermentation with specific non-Saccharomyces strain is a potential way to increase the aromatic diversity and quality of wine product, which could provide an alternative way to meet the requirement of wine consumers for diversified aromatic quality. PMID:29674999

Homogeneous purification and characterization of LePGT1--a membrane-bound aromatic substrate prenyltransferase involved in secondary metabolism of Lithospermum erythrorhizon.

PubMed

Ohara, Kazuaki; Mito, Koji; Yazaki, Kazufumi

2013-06-01

Membrane-bound type prenyltransferases for aromatic substrates play crucial roles in the biosynthesis of various natural compounds. Lithospermum erythrorhizon p-hydroxybenzoate: geranyltransferase (LePGT1), which contains multiple transmembrane α-helices, is involved in the biosynthesis of a red naphthoquinone pigment, shikonin. Taking LePGT1 as a model membrane-bound aromatic substrate prenyltransferase, we utilized a baculovirus-Sf9 expression system to generate a high yield LePGT1 polypeptide, reaching ~ 1000-fold higher expression level compared with a yeast expression system. Efficient solubilization procedures and biochemical purification methods were developed to extract LePGT1 from the membrane fraction of Sf9 cells. As a result, 80 μg of LePGT1 was purified from 150 mL culture to almost homogeneity as judged by SDS/PAGE. Using purified LePGT1, enzymatic characterization, e.g. substrate specificity, divalent cation requirement and kinetic analysis, was done. In addition, inhibition experiments revealed that aromatic compounds having two phenolic hydroxyl groups effectively inhibited LePGT1 enzyme activity, suggesting a novel recognition mechanism for aromatic substrates. As the first example of solubilization and purification of this membrane-bound protein family, the methods established in this study will provide valuable information for the precise biochemical characterization of aromatic prenyltransferases as well as for crystallographic analysis of this novel enzyme family. © 2013 The Authors Journal compilation © 2013 FEBS.

Enhanced intersystem crossing in core-twisted aromatics.

PubMed

Nagarajan, Kalaivanan; Mallia, Ajith R; Muraleedharan, Keerthi; Hariharan, Mahesh

2017-03-01

We describe the design, bottom-up synthesis and X-ray single crystal structure of systematically twisted aromatics 1c and 2d for efficient intersystem crossing. Steric congestion at the cove region creates a nonplanar geometry that induces a significant yield of triplet excited states in the electron-poor core-twisted aromatics 1c and 2d . A systematic increase in the number of twisted regions in 1c and 2d results in a concomitant enhancement in the rate and yield of intersystem crossing, monitored using femtosecond and nanosecond transient absorption spectroscopy. Time-resolved absorption spectroscopic measurements display enhanced triplet quantum yields ( Φ T = 10 ± 1% for 1c and Φ T = 30 ± 2% for 2d ) in the twisted aromatics when compared to a negligible Φ T (<1%) in the planar analog 3c . Twist-induced spin-orbit coupling via activated out-of-plane C-H/C 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 1111111111111111111111111111111111 1111111111111111111111111111111111 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 1111111111111111111111111111111111 1111111111111111111111111111111111 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 C vibrations can facilitate the formation of triplet excited states in twisted aromatics 1c and 2d , in contrast to the negligible intersystem crossing in the planar analog 3c . The ease of synthesis, high solubility, access to triplet excited states and strong electron affinity make such imide functionalized core-twisted aromatics desirable materials for organic electronics such as solar cells.

De novo transcriptome assembly and identification of the gene conferring a "pandan-like" aroma in coconut (Cocos nucifera L.).

PubMed

Saensuk, Chatree; Wanchana, Samart; Choowongkomon, Kiattawee; Wongpornchai, Sugunya; Kraithong, Tippaya; Imsabai, Wachiraya; Chaichoompu, Ekawat; Ruanjaichon, Vinitchan; Toojinda, Theerayut; Vanavichit, Apichart; Arikit, Siwaret

2016-11-01

Thailand's aromatic coconut (Cocos nucifera L.) is a special type of green dwarf coconut, the liquid endosperm of which is characterized by a pleasant "pandan-like" aroma due to the presence of 2-acetyl-1-pyrroline (2AP). The aim of this study was to perform a de novo assembly of transriptome from C. nucifera endosperm and to identify the gene responsible for 2AP biosynthesis. CnAMADH2 was identified as an ortholog of the rice aromatic gene and a G-to-C substitution found in exon 14 was associated with 2AP content in the aromatic green dwarf coconut accessions. The base substitution caused an amino-acid change, alanine-to-proline, at position 442 (P442A). The presence of P at this position might alter the steric conformation at the loop region and subsequently result in an unstabilized dimer conformation that could lower AMADH enzyme activity. Among AMADH/BADH protein sequences in different plant species, the P442A mutation was found exclusively in aromatic coconut. The PCR marker developed based on this sequence variation can perfectly detect the aromatic and non-aromatic alleles of the gene. This study confirms the hypothesis that plants may share a mechanism of 2AP biosynthesis. This is the first identification of the gene associated with 2AP biosynthesis in a tree plant. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Towards the Rational Design of Ionic Liquid Matrices for Secondary Ion Mass Spectrometry: Role of the Anion

NASA Astrophysics Data System (ADS)

Dertinger, Jennifer J.; Walker, Amy V.

2013-08-01

The role of the ionic liquid (IL) anion structure on analyte signal enhancements has been systematically investigated in secondary ion mass spectrometry (SIMS) using a variety of samples, including lipids, sterols, polymers, and peptides. Twenty-four ILs were synthesized. The 12 matrix acids were cinnamic acid derivatives. Two bases were employed: 1-methylimidazole and tripropylamine. Three matrices, methylimmidazolium o-coumarate, tripropylammonium o-coumarate, and tripropylammonium 3,4,5-trimethoxycinnamate, were "universal" matrices enhancing all analytes tested. The pKa of the matrix acid does not appear to have a strong effect on analyte ion intensities. Rather, it is observed that a single hydroxyl group on the anion aromatic ring leads to significantly increased molecular ion intensities. No analyte signal enhancements were observed for -CH3, -CF3 and -OCH3 groups present on the aromatic ring. The position of the -OH group on the aromatic ring also alters molecular ion intensity enhancements. As well as the chemical identity and position of substituents, the number of moieties on the aromatic ring may affect the analyte signal enhancements observed. These observations suggest that the activation of the IL anion aromatic ring is important for optimizing analyte signal intensities. The implications for SIMS imaging of complex structures, such as biological samples, are discussed.

Temporal dynamics of the arthropod community in pear orchards intercropped with aromatic plants.

PubMed

Beizhou, Song; Jie, Zhang; Jinghui, Hu; Hongying, Wu; Yun, Kong; Yuncong, Yao

2011-09-01

Increasing attention has been paid to enhancing biological control through habitat management in agricultural systems for enhanced pest management. Pest management benefits can be realised by intercropping, which can increase natural enemy abundance and, in turn, reduce pest abundance. In this study, the composition and temporal dynamics of arthropod communities in pear orchards when intercropped with aromatic plants were investigated, and the effectiveness and applicability of aromatic plants as intercrops for enhancing insect control were assessed. When compared with natural grasses or clean tillage, intercropping significantly reduced pest abundance and increased the ratio of natural enemies to pests. Intercropping also shortened the occurrence duration and depressed the incidence peak in annual dynamics curves of the pest subcommunity and the arthropod community, mainly because of the repellent effects of aromatic plants. Equally important, intercropping significantly reduced the numbers of major pests, such as Psylla chinensis, Aphis citricola and Pseudococcus comstocki, while their incidence period was delayed to varying degrees, and the numbers of their dominant natural enemies (Coccinella septempunctata, Phytoseiulus persimilis and Chrysoperla sinica) increased. Intercropping with aromatic plants led to a considerable improvement in arthropod pest management by enhancing the activity of the beneficial arthropod community within the pear orchard ecosystem. Copyright © 2011 Society of Chemical Industry.

Mechanism for Ring-Opening of Aromatic Polymers by Remote Atmospheric Pressure Plasma

NASA Astrophysics Data System (ADS)

Gonzalez, Eleazar; Barankin, Michael; Guschl, Peter; Hicks, Robert

2009-10-01

A low-temperature, atmospheric pressure oxygen and helium plasma was used to treat the surfaces of polyetheretherketone, polyphenylsulfone, polyethersulfone, and polysulfone. These aromatic polymers were exposed to the afterglow of the plasma, which contained oxygen atoms, and to a lesser extent metastable oxygen (^1δg O2) and ozone. After less than 2.5 seconds treatment, the polymers were converted from a hydrophobic state with a water contact angle of 85±5 to a hydrophilic state with a water contact angle of 13±5 . It was found that plasma activation increased the bond strength to adhesives by as much as 4 times. X-ray photoelectron spectroscopy revealed that between 7% and 27% of the aromatic carbon atoms on the polymer surfaces was oxidized and converted into aldehyde and carboxylic acid groups. Analysis of polyethersulfone by internal reflection infrared spectroscopy showed that a fraction of the aromatic carbon atoms were transformed into C=C double bonds, ketones, and carboxylic acids after plasma exposure. It was concluded that the oxygen atoms generated by the atmospheric pressure plasma insert into the double bonds on the aromatic rings, forming a 3-member epoxy ring, which subsequently undergoes ring opening and oxidation to yield an aldehyde and a carboxylic acid group.

Superficial distribution of aromatic compounds and geomicrobiology of sediments from Suruí Mangrove, Guanabara Bay, RJ, Brazil.

PubMed

Fontana, Luiz F; da Silva, Frederico S; de Figueiredo, Natália G; Brum, Daniel M; Netto, Annibal D Pereira; de Gigueiredo Junior, Alberto G; Crapez, Mirian A C

2010-12-01

The distribution of selected aromatic compounds and microbiology were assessed in superficial sediments from Suruí Mangrove, Guanabara Bay. Samples were collected at 23 stations, and particle size, organic matter, aromatic compounds, microbiology activity, biopolymers, and topography were determined. The concentration of aromatic compounds was distributed in patches over the entire mangrove, and their highest total concentration was determinated in the mangrove's central area. Particle size differed from most mangroves in that Suruí Mangrove has chernies on the edges and in front of the mangrove, and sand across the whole surface, which hampers the relationship between particle size and hydrocarbons. An average @ 10% p/p of organic matter was obtained, and biopolymers presented high concentrations, especially in the central and back areas of the mangrove. The biopolymers were distributed in high concentrations. The presence of fine sediments is an important factor in hydrocarbon accumulation. With high concentration of organic matter and biopolymers, and the topography with chernies and roots protecting the mangrove, calmer areas are created with the deposition of material transported by wave action. Compared to global distributions, concentrations of aromatic compounds in Suruí Mangrove may be classified from moderate to high, showing that the studied area is highly impacted.

A study of anti-inflammatory and analgesic activity of new 2,4,6-trisubstituted pyrimidines.

PubMed

Yejella, Rajendra Prasad; Atla, Srinivasa Rao

2011-01-01

Chalcone derivatives (3a-m) were prepared by condensing 4-aminoacetophenone with various substituted aromatic and hetero aromatic aldehydes according to Claisen-Schmidt condensation. These chalcones, on reaction with guanidine hydrochloride under basic alcoholic conditions gave 2,4,6-trisubstituted pyrimidines (5a-m) in quantitative yields. All the newly synthesized pyrimidines were characterized by means of IR, ¹H- and ¹³C-NMR, Electron Ionization (EI)-mass and elemental analyses and screened for anti-inflammatory and analgesic activities by in vivo. 2-amino-4-(4-aminophenyl)-6-(2,4-dichlorophenyl)pyrimidine (5b) and 2-amino-4-(4-aminophenyl)-6-(3-bromophenyl) pyrimidine (5d) were found to be the most potent anti-inflammatory and analgesic activity compared with ibuprofen, reference standard. And also it was found that compound 5b identified as lead structure among all in both the activities. Pyrimidines which showed good anti-inflammatory activity also displayed better analgesic activity.

Enhancement of the ETS-10 titanosilicate activity in the shape-selective photocatalytic degradation of large aromatic molecules by controlled defect production.

PubMed

Llabrés I Xamena, Francesc X; Calza, Paola; Lamberti, Carlo; Prestipino, Carmelo; Damin, Alessandro; Bordiga, Silvia; Pelizzetti, Ezio; Zecchina, Adriano

2003-02-26

In recent times, it has been shown that the microporous ETS-10 titanosilicate can be used as a shape-selective photocatalyst for the decomposition of aromatic molecules (Chem. Commun. 2001, 2131). Its actual use on practical grounds is however discouraged by its too low activity, when compared with that of TiO(2) photocatalysts. In the present work, we show how an ad hoc mild treatment with HF enhances the activity of ETS-10 toward the photodegradation of large aromatic molecules that are unable to penetrate inside the zeolitic pores, such as 2,5-dichlorophenol, 2,4,5-trichlorophenol, 1,3,5-trihydroxybenzene, and 2,3-dihydroxynaphthalene (DHN). The photoactivity of the acid-treated materials is comparable or even greater than that of the nonselective TiO(2) catalyst. Moreover, the enhancement of the photoactivity is accompanied by a remarkable parallel increase of the shape selectivity, particularly toward DHN (k(DHN)/k(P) = 127, where P = phenol). A complete characterization (by means of X-ray diffraction, scanning electron microscopy, transmission electron microscopy, ultraviolet-visible spectroscopy, and X-ray aborption spectroscopy techniques) of a set of ETS-10 samples which have undergone a progressively severe HF treatment allows us to propose an explanation of the photocatalytic activity and selectivity of the modified materials.

Pyridine-substituted thiazolylphenol derivatives: Synthesis, modeling studies, aromatase inhibition, and antiproliferative activity evaluation.

PubMed

Ertas, Merve; Sahin, Zafer; Berk, Barkin; Yurttas, Leyla; Biltekin, Sevde N; Demirayak, Seref

2018-04-01

Drugs used in breast cancer treatments target the suppression of estrogen biosynthesis. During this suppression, the main goal is to inhibit the aromatase enzyme that is responsible for the cyclization and structuring of estrogens either with steroid or non-steroidal-type inhibitors. Non-steroidal derivatives generally have a planar aromatic structure attached to the triazole ring system in their structures, which inhibits hydroxylation reactions during aromatization by coordinating the heme group. Bioisosteric replacement of the triazole ring system and development of aromatic/cyclic structures of the side chain can increase the selectivity for aromatase enzyme inhibition. In this study, pyridine-substituted thiazolylphenol derivatives, which are non-steroidal triazole bioisosteres, were synthesized using the Hantzsch method, and physical analysis and structural determination studies were performed. The IC 50 values of the compounds were determined by a fluorescence-based aromatase inhibition assay. Then, their antiproliferative activities on the MCF7 and HEK 293 cell lines were evaluated with the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Furthermore, the crystal structure of human placental aromatase was subjected to a series of docking experiments to identify the possible interactions between the most active structure and the active site. Lastly, an in silico technique was performed to analyze and predict the drug-likeness, molecular and ADME properties of the synthesized molecules. © 2018 Deutsche Pharmazeutische Gesellschaft.

The role of turmerones on curcumin transportation and P-glycoprotein activities in intestinal Caco-2 cells.

PubMed

Yue, Grace G L; Cheng, Sau-Wan; Yu, Hua; Xu, Zi-Sheng; Lee, Julia K M; Hon, Po-Ming; Lee, Mavis Y H; Kennelly, Edward J; Deng, Gary; Yeung, Simon K; Cassileth, Barrie R; Fung, Kwok-Pui; Leung, Ping-Chung; Lau, Clara B S

2012-03-01

The rhizome of Curcuma longa (turmeric) is often used in Asia as a spice and as a medicine. Its most well-studied component, curcumin, has been shown to exhibit poor bioavailability in animal studies and clinical trials. We hypothesized that the presence of lipophilic components (e.g., turmerones) in turmeric extract would affect the absorption of curcumin. The effects of turmerones on curcumin transport were evaluated in human intestinal epithelial Caco-2 cells. The roles of turmerones on P-glycoprotein (P-gp) activities and mRNA expression were also evaluated. Results showed that in the presence of α- and aromatic turmerones, the amount of curcumin transported into the Caco-2 cells in 2 hours was significantly increased. α-Turmerone and verapamil (a P-gp inhibitor) significantly inhibited the efflux of rhodamine-123 and digoxin (i.e., inhibited the activity of P-gp). It is interesting that aromatic turmerone significantly increased the rhodamine-123 efflux and P-gp (MDR1 gene) mRNA expression levels. The effects of α- and aromatic turmerones on curcumin transport as well as P-gp activities were shown here for the first time. The presence of turmerones did affect the absorption of curcumin in vitro. These findings suggest the potential use of turmeric extract (including curcumin and turmerones), rather than curcumin alone, for treating diseases.

Improvement of aromatic thiol release through the selection of yeasts with increased β-lyase activity.

PubMed

Belda, Ignacio; Ruiz, Javier; Navascués, Eva; Marquina, Domingo; Santos, Antonio

2016-05-16

The development of a selective medium for the rapid differentiation of yeast species with increased aromatic thiol release activity has been achieved. The selective medium was based on the addition of S-methyl-l-cysteine (SMC) as β-lyase substrate. In this study, a panel of 245 strains of Saccharomyces cerevisiae strains was tested for their ability to grow on YCB-SMC medium. Yeast strains with an increased β-lyase activity grew rapidly because of their ability to release ammonium from SMC in comparison to others, and allowed for the easy isolation and differentiation of yeasts with promising properties in oenology, or another field, for aromatic thiol release. The selective medium was also helpful for the discrimination between those S. cerevisiae strains, which present a common 38-bp deletion in the IRC7 sequence (present in around 88% of the wild strains tested and are likely to be less functional for 4-mercapto-4-methylpentan-2-one (4MMP) production), and those S. cerevisiae strains homozygous for the full-length IRC7 allele. The medium was also helpful for the selection of non-Saccharomyces yeasts with increased β-lyase activity. Based on the same medium, a highly sensitive, reproducible and non-expensive GC-MS method for the evaluation of the potential volatile thiol release by different yeast isolates was developed. Copyright © 2016 Elsevier B.V. All rights reserved.

The Role of Turmerones on Curcumin Transportation and P-Glycoprotein Activities in Intestinal Caco-2 Cells

PubMed Central

Yue, Grace G.L.; Cheng, Sau-Wan; Yu, Hua; Xu, Zi-Sheng; Lee, Julia K.M.; Hon, Po-Ming; Lee, Mavis Y.H.; Kennelly, Edward J.; Deng, Gary; Yeung, Simon K.; Cassileth, Barrie R.; Fung, Kwok-Pui; Leung, Ping-Chung

2012-01-01

Abstract The rhizome of Curcuma longa (turmeric) is often used in Asia as a spice and as a medicine. Its most well-studied component, curcumin, has been shown to exhibit poor bioavailability in animal studies and clinical trials. We hypothesized that the presence of lipophilic components (e.g., turmerones) in turmeric extract would affect the absorption of curcumin. The effects of turmerones on curcumin transport were evaluated in human intestinal epithelial Caco-2 cells. The roles of turmerones on P-glycoprotein (P-gp) activities and mRNA expression were also evaluated. Results showed that in the presence of α- and aromatic turmerones, the amount of curcumin transported into the Caco-2 cells in 2 hours was significantly increased. α-Turmerone and verapamil (a P-gp inhibitor) significantly inhibited the efflux of rhodamine-123 and digoxin (i.e., inhibited the activity of P-gp). It is interesting that aromatic turmerone significantly increased the rhodamine-123 efflux and P-gp (MDR1 gene) mRNA expression levels. The effects of α- and aromatic turmerones on curcumin transport as well as P-gp activities were shown here for the first time. The presence of turmerones did affect the absorption of curcumin in vitro. These findings suggest the potential use of turmeric extract (including curcumin and turmerones), rather than curcumin alone, for treating diseases. PMID:22181075

Complexation of C60 fullerene with aromatic drugs.

PubMed

Evstigneev, Maxim P; Buchelnikov, Anatoly S; Voronin, Dmitry P; Rubin, Yuriy V; Belous, Leonid F; Prylutskyy, Yuriy I; Ritter, Uwe

2013-02-25

The contributions of various physical factors to the energetics of complexation of aromatic drug molecules with C(60) fullerene are investigated in terms of the calculated magnitudes of equilibrium complexation constants and the components of the net Gibbs free energy. Models of complexation are developed taking into account the polydisperse nature of fullerene solutions in terms of the continuous or discrete (fractal) aggregation of C(60) molecules. Analysis of the energetics has shown that stabilization of the ligand-fullerene complexes in aqueous solution is mainly determined by intermolecular van der Waals interactions and, to lesser extent, by hydrophobic interactions. The results provide a physicochemical basis for a potentially new biotechnological application of fullerenes as modulators of biological activity of aromatic drugs. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ionic liquid mediated synthesis and molecular docking study of novel aromatic embedded Schiff bases as potent cholinesterase inhibitors.

PubMed

Abd Razik, Basma M; Osman, Hasnah; Basiri, Alireza; Salhin, Abdussalam; Kia, Yalda; Ezzat, Mohammed Oday; Murugaiyah, Vikneswaran

2014-12-01

Novel aromatic embedded Schiff bases have been synthesized in ionic liquid [bmim]Br and evaluated in vitro for their acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) enzymes inhibitory activities. Among the newly synthesized compounds, 5f, 5h and 7j displayed higher AChE enzyme inhibitory activities than standard drug, galanthamine, with IC50 values of 1.88, 2.05 and 2.03μM, respectively. Interestingly, all the compounds except for compound 5c displayed higher BChE inhibitories than standard with IC50 values ranging from 3.49 to 19.86μM. Molecular docking analysis for 5f and 7j possessing the most potent AChE and BChE inhibitory activities, disclosed their binding interaction templates to the active site of AChE and BChE enzymes, respectively. Copyright © 2014 Elsevier Inc. All rights reserved.

Identification and characterization of epoxide hydrolase activity of polycyclic aromatic hydrocarbon-degrading bacteria for biocatalytic resolution of racemic styrene oxide and styrene oxide derivatives.

PubMed

Woo, Jung-Hee; Kwon, Tae-Hyung; Kim, Jun-Tae; Kim, Choong-Gon; Lee, Eun Yeol

2013-04-01

A novel epoxide hydrolase (EHase) from polycyclic aromatic hydrocarbon (PAH)-degrading bacteria was identified and characterized. EHase activity was identified in four strains of PAH-degrading bacteria isolated from commercial gasoline and oil-contaminated sediment based on their growth on styrene oxide and its derivatives, such as 2,3- and 4-chlorostyrene oxides, as a sole carbon source. Gordonia sp. H37 exhibited high enantioselective hydrolysis activity for 4-chlorostyrene oxide with an enantiomeric ratio of 27. Gordonia sp. H37 preferentially hydrolyzed the (R)-enantiomer of styrene oxide derivatives resulting in the preparation of a (S)-enantiomer with enantiomeric excess greater than 99.9 %. The enantioselective EHase activity was identified and characterized in various PAH-degrading bacteria, and whole cell Gordonia sp. H37 was employed as a biocatalyst for preparing enantiopure (S)-styrene oxide derivatives.

Sequence inversion and phenylalanine surrogates at the beta-turn enhance the antibiotic activity of gramicidin S.

PubMed

Solanas, Concepción; de la Torre, Beatriz G; Fernández-Reyes, María; Santiveri, Clara M; Jiménez, M Angeles; Rivas, Luis; Jiménez, Ana I; Andreu, David; Cativiela, Carlos

2010-05-27

A series of gramicidin S (GS) analogues have been synthesized where the Phe (i + 1) and Pro (i + 2) residues of the beta-turn have been swapped while the respective chiralities (D-, L-) at each position are preserved, and Phe is replaced by surrogates with aromatic side chains of diverse size, orientation, and flexibility. Although most analogues preserve the beta-sheet structure, as assessed by NMR, their antibiotic activities turn out to be highly dependent on the bulkiness and spatial arrangement of the aromatic side chain. Significant increases in microbicidal potency against both Gram-positive and Gram-negative pathogens are observed for several analogues, resulting in improved therapeutic profiles. Data indicate that seemingly minor replacements at the GS beta-turn can have significant impact on antibiotic activity, highlighting this region as a hot spot for modulating GS plasticity and activity.

Sequence inversion and phenylalanine surrogates at the β-turn enhance the antibiotic activity of gramicidin S

PubMed Central

Solanas, Concepción; de la Torre, Beatriz G.; Fernández-Reyes, María; Santiveri, Clara M.; Jiménez, M. Ángeles; Rivas, Luis; Jiménez, Ana I.; Andreu, David; Cativiela, Carlos

2010-01-01

A series of gramicidin S (GS) analogs have been synthesized where the Phe (i+1) and Pro (i+2) residues of the β-turn have been swapped while the respective chiralities (D-, L-) at each position are preserved, and Phe is replaced by surrogates with aromatic side chains of diverse size, orientation and flexibility. Although most analogs preserve the β-sheet structure, as assessed by NMR, their antibiotic activities turn out to be highly dependent on the bulkiness and spatial arrangement of the aromatic side chain. Significant increases in microbicidal potency against both Gram-positive and Gram-negative pathogens are observed for several analogs, resulting in improved therapeutic profiles. Data indicate that seemingly minor replacements at the GS β-turn can have significant impact on antibiotic activity, highlighting this region as a hot spot for modulating GS plasticity and activity. PMID:20411945

Antioxidant activity of selenenamide-based mimic as a function of the aromatic thiols nucleophilicity, a DFT-SAPE model.

PubMed

Kheirabadi, Ramesh; Izadyar, Mohammad

2018-05-18

The mechanism of action of the selenenamide 1 as a mimic of the glutathione peroxidase (GPx) was investigated by the density functional theory. The solvent-assisted proton exchange procedure was applied to model the catalytic behavior and antioxidant activity of this mimic. To have an insight into the charge transfer effect, different aromatic thiols, including electron donating substituents on the phenyl ring were considered. The catalytic behavior of the selenenamide was modeled in a four-step mechanism, described by the oxidation of the mimic, the reduction of the obtained product, selenoxide, the reduction of the selenenylsulfide and dehydration of selenenic acid. On the basis of the activation parameters, the final step of the proposed mechanism is the rate determining states of the catalytic cycle. Turnover frequency (TOF) analysis showed that the electron donating groups at the para-position of the phenyl ring of the PhSH do not affect the catalytic activity of the selenenamide in contrast to p-methyl thiophenol which indicates the highest nucleophilicity. The evaluation of the electronic contribution of the various donating groups on the phenyl ring of the aromatic thiols shows that the antioxidant activity of the selenenamide sufficiently increases in the presence of the electron-donating substitutions. Finally, the charge transfer process at the rate-determining state was investigated based on the natural bond orbital analysis. Copyright © 2018 Elsevier Ltd. All rights reserved.

Pistachio oil (Pistacia vera L. cv. Uzun): Characterization of key odorants in a representative aromatic extract by GC-MS-olfactometry and phenolic profile by LC-ESI-MS/MS.

PubMed

Sonmezdag, Ahmet Salih; Kelebek, Hasim; Selli, Serkan

2018-02-01

Volatile, aroma-active, and phenolic compounds of pistachio oil obtained from cv. Uzun were investigated in the current study. To obtain a representative aromatic extract, three of the most widely used extraction methods were compared using a representative test; the solvent-assisted flavour extraction (SAFE) aromatic extract from pistachio oil was found to be the most representative. A total of 50 aroma compounds were determined in pistachio oil and it was found that terpenes, aldehydes, and alcohols were the most abundant volatile compounds. Applying GC-MS-olfactometry and aroma extract dilution analysis (AEDA) resulted in a total of 14 aroma-active areas being detected in the extract of pistachio oil. In the phenolic fraction obtained by the LC-ESI-MS/MS method, a total of 12 phenolic compounds was found in the pistachio oil, of which seven compounds were reported for the first time. Eriodictyol-7-O-glucoside and protocatechuic acid were the most dominant phenolic compounds. Copyright © 2017 Elsevier Ltd. All rights reserved.

Aromatic Polyketide GTRI-02 is a Previously Unidentified Product of the act Gene Cluster in Streptomyces coelicolor A3(2).

PubMed

Wu, Changsheng; Ichinose, Koji; Choi, Young Hae; van Wezel, Gilles P

2017-07-18

The biosynthesis of aromatic polyketides derived from type II polyketide synthases (PKSs) is complex, and it is not uncommon that highly similar gene clusters give rise to diverse structural architectures. The act biosynthetic gene cluster (BGC) of the model actinomycete Streptomyces coelicolor A3(2) is an archetypal type II PKS. Here we show that the act BGC also specifies the aromatic polyketide GTRI-02 (1) and propose a mechanism for the biogenesis of its 3,4-dihydronaphthalen-1(2H)-one backbone. Polyketide 1 was also produced by Streptomyces sp. MBT76 after activation of the act-like qin gene cluster by overexpression of the pathway-specific activator. Mining of this strain also identified dehydroxy-GTRI-02 (2), which most likely originated from dehydration of 1 during the isolation process. This work shows that even extensively studied model gene clusters such as act of S. coelicolor can still produce new chemistry, offering new perspectives for drug discovery. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Opioid Receptor Probes Derived from Cycloaddition of the Hallucinogen Natural Product Salvinorin A†

PubMed Central

Lozama, Anthony; Cunningham, Christopher W.; Caspers, Michael J.; Douglas, Justin T.; Dersch, Christina M.; Rothman, Richard B.; Prisinzano, Thomas E.

2011-01-01

As part of our continuing efforts toward more fully understanding the structure-activity relationships of the neoclerodane diterpene salvinorin A, we report the synthesis and biological characterization of unique cycloadducts through [4+2] Diels-Alder cycloaddition. Microwave-assisted methods were developed and successfully employed, aiding in functionalizing the chemically sensitive salvinorin A scaffold. This demonstrates the first reported results for both cycloaddition of the furan ring and functionalization via microwave-assisted methodology of the salvinorin A skeleton. The cycloadducts yielded herein introduce electron-withdrawing substituents and bulky aromatic groups into the C-12 position. Kappa opioid (KOP) receptor space was explored through aromatization of the bent oxanorbornadiene system possessed by the cycloadducts to a planar phenyl ring system. Although dimethyl- and diethylcarboxylate analogues 5 and 6 retain some affinity and selectivity for KOP receptors and are full agonists, their aromatized counterparts 13 and 14 have reduced affinity for KOP receptors. The methods developed herein signify a novel approach toward rapidly probing the structure-activity relationships of furan containing natural products. PMID:21338114

Sorption of Aromatic Compounds with Copolymer Sorbent Materials Containing β-Cyclodextrin.

PubMed

Wilson, Lee D; Mohamed, Mohamed H; Berhaut, Christopher L

2011-08-29

Urethane copolymer sorbent materials that incorporate β-cyclodextrin (CD) have been prepared and their sorption properties with chlorinated aromatic compounds (i.e., pentachlorophenol, 2,4-dichlorophenol and 2,4-dichlorophenoxy acetic acid) have been evaluated. The sorption properties of granular activated carbon (GAC) were similarly compared in aqueous solution at variable pH conditions. The sorbents displayed variable BET surface areas as follows: MDI-X copolymers (< 10¹ m²/g), CDI-X copolymers (< 10¹ m²/g), and granular activated carbon (GAC ~10³ m²/g). The sorption capacities for the copolymers sorbents are listed in descending order, as follows: GAC > CDI-3 copolymer ≈ MDI-3 copolymer. The sorption capacity for the aromatic adsorbates with each sorbent are listed in descending order, as follows: 2,4-dichlorophenol > 2,4-dichlorophenoxy acetic acid > pentachlorophenol. In general, the differences in the sorption properties of the copolymer sorbents with the chlorinated organics were related to the following factors: (i) surface area of the sorbent; (ii) CD content and accessibility; and (iii) and the chemical nature of the sorbent material.

Sorption of Aromatic Compounds with Copolymer Sorbent Materials Containing β-Cyclodextrin

PubMed Central

Wilson, Lee D.; Mohamed, Mohamed H.; Berhaut, Christopher L.

2011-01-01

Urethane copolymer sorbent materials that incorporate β-cyclodextrin (CD) have been prepared and their sorption properties with chlorinated aromatic compounds (i.e., pentachlorophenol, 2,4-dichlorophenol and 2,4-dichlorophenoxy acetic acid) have been evaluated. The sorption properties of granular activated carbon (GAC) were similarly compared in aqueous solution at variable pH conditions. The sorbents displayed variable BET surface areas as follows: MDI-X copolymers (< 101 m2/g), CDI-X copolymers (< 101 m2/g), and granular activated carbon (GAC ~103 m2/g). The sorption capacities for the copolymers sorbents are listed in descending order, as follows: GAC > CDI-3 copolymer ≈ MDI-3 copolymer. The sorption capacity for the aromatic adsorbates with each sorbent are listed in descending order, as follows: 2,4-dichlorophenol > 2,4-dichlorophenoxy acetic acid > pentachlorophenol. In general, the differences in the sorption properties of the copolymer sorbents with the chlorinated organics were related to the following factors: (i) surface area of the sorbent; (ii) CD content and accessibility; and (iii) and the chemical nature of the sorbent material. PMID:28824156

Synthesis and antifungal activity of C-21 steroids with an aromatic D ring.

PubMed

Sonego, Juan M; Cirigliano, Adriana M; Cabrera, Gabriela M; Burton, Gerardo; Veleiro, Adriana S

2013-07-01

Six analogues of salpichrolides with a simplified side chain (6-11) were synthesized using a new methodology to obtain steroids with an aromatic D-ring. The key step was the elimination of HBr in a vicinal dibromo D-homosteroid by treatment with 1,4-diazabicyclo[2.2.2]octane (DABCO). All new compounds were completely characterized by 2D NMR techniques and tested on two fungal pathogenic species, Fusarium virguliforme and Fusarium solani. Copyright © 2013 Elsevier Inc. All rights reserved.

Radiation-resistant, amorphous, all-aromatic poly(arylene ether sulfones) - Synthesis, physical behavior, and degradation characteristics

NASA Technical Reports Server (NTRS)

Lewis, D. A.; O'Donnell, James H.; Hedrick, J. L.; Ward, T. C.; Mcgrath, J. E.

1989-01-01

The effects of Co-60 gamma radiation on a series of poly(arylene ether sulfones) prepared by nucleophilic activated aromatic substitution are investigated experimentally. The preparation of the test compounds is described, and the test results are presented in extensive tables and graphs. Radiation-induced degradation, as measured by SO2 production, was found to be lowest in compounds based on biphenol rather than bisphenol A; these findings were also well correlated with ultimate-tensile-strain measurements.

2-Aminoquinazolin-4(3H)-one as an Organocatalyst for the Synthesis of Tertiary Amines.

PubMed

Thakur, Maheshwar S; Nayal, Onkar S; Upadhyay, Rahul; Kumar, Neeraj; Maurya, Sushil K

2018-03-02

The potential of 2-aminoquinazolin-4(3H)-one as an organocatalyst for the activation of aldehydes via noncovalent interaction for the synthesis of tertiary amines using formic acid as a reducing agent is reported for the first time. The developed protocol demonstrated a dilated substrate scope for aromatic and aliphatic amines with aromatic and aliphatic aldehydes. Furthermore, the current method was also fruitful for the derivatization of ciprofloxacin and its derivative in good to excellent yields.

Effects of environmental pollution with aromatic hydrocarbons on endocrine and metabolic functions of the human placenta.

PubMed

Wierzba, Waldemar; Radowicki, Stanisław; Bojar, Iwona; Pinkas, Jarosław

2018-03-14

Phenol and 1-hydroxypyrene are biological markers of exposure to polycyclic aromatic hydrocarbons (PAH) that have certain negative effects on parenchymal organs such as the human placenta. The literature presents only few reports regarding the effects of elevated PAH levels on the functions of the human placenta. The aim of the work is to assess the effects of elevated PAH levels in excreted urine on the endocrine and metabolic functions of the human placenta obtained from a normal pregnancy. Tissue material from 50 afterbirths from Płock constituted a study group, whereas 50 afterbirths from Kutno constituted a control group. Immunohistochemical reactions with the peroxidase method using LSAB kits (DAKO, Denmark) were performed. The extent and intensity of reactions were analysed. The levels of phenols and 1-hydroxypyrene in the excreted urine of pregnant women (undergoing delivery) were detected using gas chromatography and colorimetry. The statistical analysis used the PQStat v.1.6.2 software; moreover, t-student and chi-square tests were used. Differences were considered to be significant at the significance level of 95% (p<0.05). The levels of phenol and 1-hydroxypyrene in the excreted urine were demonstrated to be statistically significantly higher in patients living in the area of Płock. Statistically lower expression of placental glutathione transferase and lower immunohistochemical demonstration of the placental phosphatase activity were observed in placentas from Płock. It has been demonstrated that the expression of the oestrogen receptor activity and placental gonadotropin is significantly higher in placentas from areas not contaminated with aromatic hydrocarbons (Kutno). The course of pregnancy in the environment with elevated levels of aromatic hydrocarbons leads to impaired placental functioning and reduced endocrine and metabolic activity of the placenta.

Structure and function of CYP108D1 from Novosphingobium aromaticivorans DSM12444: an aromatic hydrocarbon-binding P450 enzyme.

PubMed

Bell, Stephen G; Yang, Wen; Yorke, Jake A; Zhou, Weihong; Wang, Hui; Harmer, Jeffrey; Copley, Rachel; Zhang, Aili; Zhou, Ruimin; Bartlam, Mark; Rao, Zihe; Wong, Luet Lok

2012-03-01

CYP108D1 from Novosphingobium aromaticivorans DSM12444 binds a range of aromatic hydrocarbons such as phenanthrene, biphenyl and phenylcyclohexane. Its structure, which is reported here at 2.2 Å resolution, is closely related to that of CYP108A1 (P450terp), an α-terpineol-oxidizing enzyme. The compositions and structures of the active sites of these two enzymes are very similar; the most significant changes are the replacement of Glu77 and Thr103 in CYP108A1 by Thr79 and Val105 in CYP108D1. Other residue differences lead to a larger and more hydrophobic access channel in CYP108D1. These structural features are likely to account for the weaker α-terpineol binding by CYP108D1 and, when combined with the presence of three hydrophobic phenylalanine residues in the active site, promote the binding of aromatic hydrocarbons. The haem-proximal surface of CYP108D1 shows a different charge distribution and topology to those of CYP101D1, CYP101A1 and CYP108A1, including a pronounced kink in the proximal loop of CYP108D1, which may result in poor complementarity with the [2Fe-2S] ferredoxins Arx, putidaredoxin and terpredoxin that are the respective redox partners of these three P450 enzymes. The unexpectedly low reduction potential of phenylcyclohexane-bound CYP108D1 (-401 mV) may also contribute to the low activity observed with these ferredoxins. CYP108D1 appears to function as an aromatic hydrocarbon hydroxylase that requires a different electron-transfer cofactor protein.

Enhancement of anti-inflammatory activity of Aloe vera adventitious root extracts through the alteration of primary and secondary metabolites via salicylic acid elicitation.

PubMed

Lee, Yun Sun; Ju, Hyun Kyoung; Kim, Yeon Jeong; Lim, Tae-Gyu; Uddin, Md Romij; Kim, Yeon Bok; Baek, Jin Hong; Kwon, Sung Won; Lee, Ki Won; Seo, Hak Soo; Park, Sang Un; Yang, Tae-Jin

2013-01-01

Aloe vera (Asphodeloideae) is a medicinal plant in which useful secondary metabolites are plentiful. Among the representative secondary metabolites of Aloe vera are the anthraquinones including aloe emodin and chrysophanol, which are tricyclic aromatic quinones synthesized via a plant-specific type III polyketide biosynthesis pathway. However, it is not yet clear which cellular responses can induce the pathway, leading to production of tricyclic aromatic quinones. In this study, we examined the effect of endogenous elicitors on the type III polyketide biosynthesis pathway and identified the metabolic changes induced in elicitor-treated Aloe vera adventitious roots. Salicylic acid, methyl jasmonate, and ethephon were used to treat Aloe vera adventitious roots cultured on MS liquid media with 0.3 mg/L IBA for 35 days. Aloe emodin and chrysophanol were remarkably increased by the SA treatment, more than 10-11 and 5-13 fold as compared with untreated control, respectively. Ultra-performance liquid chromatography-electrospray ionization mass spectrometry analysis identified a total of 37 SA-induced compounds, including aloe emodin and chrysophanol, and 3 of the compounds were tentatively identified as tricyclic aromatic quinones. Transcript accumulation analysis of polyketide synthase genes and gas chromatography mass spectrometry showed that these secondary metabolic changes resulted from increased expression of octaketide synthase genes and decreases in malonyl-CoA, which is the precursor for the tricyclic aromatic quinone biosynthesis pathway. In addition, anti-inflammatory activity was enhanced in extracts of SA-treated adventitious roots. Our results suggest that SA has an important role in activation of the plant specific-type III polyketide biosynthetic pathway, and therefore that the efficacy of Aloe vera as medicinal agent can be improved through SA treatment.

Enhancement of Anti-Inflammatory Activity of Aloe vera Adventitious Root Extracts through the Alteration of Primary and Secondary Metabolites via Salicylic Acid Elicitation

PubMed Central

Lee, Yun Sun; Ju, Hyun Kyoung; Kim, Yeon Jeong; Lim, Tae-Gyu; Uddin, Md Romij; Kim, Yeon Bok; Baek, Jin Hong; Kwon, Sung Won; Lee, Ki Won; Seo, Hak Soo; Park, Sang Un; Yang, Tae-Jin

2013-01-01

Aloe vera (Asphodeloideae) is a medicinal plant in which useful secondary metabolites are plentiful. Among the representative secondary metabolites of Aloe vera are the anthraquinones including aloe emodin and chrysophanol, which are tricyclic aromatic quinones synthesized via a plant-specific type III polyketide biosynthesis pathway. However, it is not yet clear which cellular responses can induce the pathway, leading to production of tricyclic aromatic quinones. In this study, we examined the effect of endogenous elicitors on the type III polyketide biosynthesis pathway and identified the metabolic changes induced in elicitor-treated Aloe vera adventitious roots. Salicylic acid, methyl jasmonate, and ethephon were used to treat Aloe vera adventitious roots cultured on MS liquid media with 0.3 mg/L IBA for 35 days. Aloe emodin and chrysophanol were remarkably increased by the SA treatment, more than 10–11 and 5–13 fold as compared with untreated control, respectively. Ultra-performance liquid chromatography-electrospray ionization mass spectrometry analysis identified a total of 37 SA-induced compounds, including aloe emodin and chrysophanol, and 3 of the compounds were tentatively identified as tricyclic aromatic quinones. Transcript accumulation analysis of polyketide synthase genes and gas chromatography mass spectrometry showed that these secondary metabolic changes resulted from increased expression of octaketide synthase genes and decreases in malonyl-CoA, which is the precursor for the tricyclic aromatic quinone biosynthesis pathway. In addition, anti-inflammatory activity was enhanced in extracts of SA-treated adventitious roots. Our results suggest that SA has an important role in activation of the plant specific-type III polyketide biosynthetic pathway, and therefore that the efficacy of Aloe vera as medicinal agent can be improved through SA treatment. PMID:24358188

Effect and mechanism of persulfate activated by different methods for PAHs removal in soil

EPA Science Inventory

The influence of persulfate activation methods on polycyclic aromatic hydrocarbons (PAHs) degradation was investigated and included thermal, citrate chelated iron, and alkaline, and a hydrogen peroxide(H2O2)-persulfate binary mixture. Thermal activation (60◦C) resulted in t...

Investigations of Chemical and Biological Treatment Options for the Attenuation of Hexahydro-1,3,5-trinitro-1,3,5-triazine Contamination in Groundwater at Los Alamos, New Mexico

NASA Astrophysics Data System (ADS)

Heerspink, B. P.; Wang, D.; Ware, D.; Marina, O.; Perkins, G.; WoldeGabriel, G. W.; Goering, T.; Boukhalfa, H.

2017-12-01

High-explosive compounds including hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) were used extensively in weapons research and testing at Los Alamos National Laboratory (LANL) in Los Alamos, NM. Liquid effluents containing RDX released at LANL's Technical Area 16 (TA-16) resulted in the contamination of alluvial, perched-intermediate, and regional groundwater bodies. Past investigations have shown persistent RDX contamination in the perched-intermediate zone located between 225 to 311 m below ground surface, where transport studies have shown that RDX and its degradation products transport conservatively. In this study, we compared RDX degradation by chemical treatments using reduction by sodium dithionite, oxidation by potassium permanganate, and alkaline hydrolysis by carbonate/bicarbonate buffering, with microbial degradation under biostimulated conditions. The experiments were conducted using groundwater and sediments representative of the contaminated aquifer beneath TA-16. Batch testing showed that all chemical treatments degraded RDX very rapidly, with half-lives ranging from 50 minutes to 22 hours. Comparatively, RDX degradation in biostimulated reactors under strict anaerobic conditions was significantly slower, with half-lives of about 3 weeks. Results from column experiments with chemically treated sediments deviated from the results of the batch testing. Dithionite treated sediments reduced RDX with no breakthrough observed before clogging occurred at 50 pour volumes. Treatments by oxidation using potassium permanganate, and hydrolysis under buffered alkaline conditions, were less effective with complete RDX breakthrough after 2 pore volumes. No known degradation products were observed in the column effluents. RDX degradation in biostimulated columns was very effective initially for both treatments. However, the column biostimulated with safflower oil clogged very rapidly. The column biostimulated with molasses was very effective when molasses was continuously supplied but less effective after molasses injection stopped. Degradation products (hexahydro-1-nitroso-3,5-dinitro-1,3,5-triazine [MNX]; hexahydro-1,3-dinitro-5-nitro-1,3,5-triazine [DNX]; 2,4,6-trinitroxylene [TNX]) were visible in the effluents from the biostimulated columns.

Smoke-derived karrikin perception by the α/β-hydrolase KAI2 from Arabidopsis.

PubMed

Guo, Yongxia; Zheng, Zuyu; La Clair, James J; Chory, Joanne; Noel, Joseph P

2013-05-14

Genetic studies in Arabidopsis implicate an α/β-hydrolase, KARRIKIN-INSENSITIVE 2 (KAI2) as a receptor for karrikins, germination-promoting butenolide small molecules found in the smoke of burned plants. However, direct biochemical evidence for the interaction between KAI2 and karrikin and for the mechanism of downstream signaling by a KAI2-karrikin complex remain elusive. We report crystallographic analyses and ligand-binding experiments for KAI2 recognition of karrikins. The karrikin-1 (KAR1) ligand sits in the opening to the active site abutting a helical domain insert but distal from the canonical catalytic triad (Ser95-His246-Asp217) of α/β-hydrolases, consistent with the lack of detectable hydrolytic activity by purified KAI2. The closest approach of KAR1 to Ser95-His246-Asp217 is 3.8 Å from His246. Six aromatic side chains, including His246, encapsulate KAR1 through geometrically defined aromatic-aromatic interactions. KAR1 binding induces a conformational change in KAI2 at the active site entrance. A crevice of hydrophobic residues linking the polar edge of KAR1 and the helical domain insert suggests that KAI2-KAR1 creates a contiguous interface for binding signaling partners in a ligand-dependent manner.

Utilization of lignocellulosic polysaccharides

NASA Astrophysics Data System (ADS)

Fenske, John James

Lignocellulosic biomass represents a vast supply of fermentable carbohydrates and functional aromatic compounds. Conversion of lignocellulosics to ethanol and other useful products would be of widespread economical and environmental benefit. Better understanding of the behavior of different lignocellulosic feedstocks in fermentation protocols as well as catalytic activities involved in lignocellulosic depolymerization will further enhance the commercial viability of biomass-to-ethanol conversion processes. The relative toxicity of the combined non-xylose components in prehydrolysates derived from three different lignocellulosic biomass feedstocks (poplar, corn stover and switchgrass, or Panicum virgatum L.) was determined using a Pichia stipits fermentation assay. The relative toxicity of the prehydrolysates, in decreasing order, was poplar-derived prehydrolysates > switchgrass-derived prehydrolysates > corn stover-derived prehydrolysates. Ethanol yields averaged 74%, 83% and 88% of control values for poplar, switchgrass and corn stover prehydrolysates, respectively. Volumetric ethanol productivities (g ethanol lsp{-1} hsp{-1}) averaged 32%, 70% and 102% of control values for poplar, switchgrass and corn stover prehydrolysates, respectively. Ethanol productivities correlated closely with acetate concentrations in the prehydrolysates; however, regression lines correlating acetate concentrations and ethanol productivities were found to be feedstock-dependent. Differences in the relative toxicity of xylose-rich prehydrolysates derived from woody and herbaceous feedstocks are likely due to the relative abundance of a variety of inhibitory compounds, e.g. acetate and aromatic compounds. Fourteen aromatic monomers present in prehydrolysates prepared from corn stover, switchgrass, and poplar were tentatively identified by comparison with published mass spectra. The concentrations of the aromatic monomers totaled 112, 141 and 247 mg(l)sp{-1} for corn stover, switchgrass and poplar prehydrolysates, respectively. The woody and herbaceous feedstocks differed in both amount and type of aromatic monomers. The cellulases of Trichoderma reesei are the most widely studied for use in the depolymerization of lignocellulosics. The Trichoderma cellobiohydrolases CBH1 and CBH2 are traditionally categorized as exo-acting cellulases. A simple individual-based model was created to explore the potential effects of native endo activity on substrate-velocity profiles. The model results indicate that an enzyme with a small amount of endo activity will show an apparent substrate inhibition as substrate levels are increased. Actual hydrolysis studies using affinity chromatography-purified CBH2 preparations from three laboratories indicate that CBH2 has native endo activity, while CBH1 does not.

A Spectrophotometric Assay Optimizing Conditions for Pepsin Activity.

ERIC Educational Resources Information Center

Harding, Ethelynda E.; Kimsey, R. Scott

1998-01-01

Describes a laboratory protocol optimizing the conditions for the assay of pepsin activity using the Coomasie Blue dye binding assay of protein concentration. The dye bonds through strong, noncovalent interactions to basic and aromatic amino acid residues. (DDR)

Surface chemistry of aromatic reactants on Pt- and Mo-modified Pt catalysts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Robinson, Allison M.; Mark, Lesli; Rasmussen, Mathew J.

Supported catalysts containing an oxophilic metal such as Mo and a noble metal such as Pt have shown promising activity and selectivity for deoxygenation of biomass-derived compounds. Here, we report that PtMo catalysts also promote hydrogenolysis of the model compound benzyl alcohol, while decarbonylation is most prevalent over unmodified Pt. A combination of single crystal surface science studies, density functional theory (DFT) calculations, and vapor phase upgrading experiments using supported catalysts was carried out to better understand the mechanism by which Mo promotes deoxygenation. Molybdenum was deposited in submonolayer quantities on a Pt(111) surface and reduced at high temperature. Temperature-programmedmore » desorption (TPD) experiments using benzyl alcohol as a reactant showed greatly enhanced yields of the deoxygenation product toluene at moderate Mo coverages. To understand how the interaction of the aromatic group with the surface influenced this reactivity, we investigated the adsorption of toluene as a probe molecule. We found that the addition of Mo to Pt(111) resulted in a significant decrease in toluene decomposition. DFT calculations indicated that this decrease was consistent with decreased aromatic adsorption strengths that accompany incorporation of Mo into the Pt subsurface. The weaker aromatic-surface interaction on Pt/Mo surfaces led to a tilted adsorption geometry for benzyl alcohol, which presumably promotes hydrogenolysis to produce toluene instead of decarbonylation to produce benzene and CO. Alumina-supported Pt and PtMo catalysts were also tested for benzyl alcohol deoxygenation. PtMo catalysts had a higher rate of toluene production and lower rates of benzene and benzaldehyde production. Additionally, when benzaldehyde was used as the reactant to measure decarbonylation activity the mass-normalized rate of benzene production was 2.5 times higher on Pt than PtMo. Altogether, the results of TPD, DFT, and supported catalyst experiments suggest that subsurface Mo sites weaken the binding of aromatic rings on PtMo surfaces; the weakened aromatic-surface interaction is correlated with an improvement in selectivity to C-O bond scission.« less

In Vitro Enzymatic Depolymerization of Lignin with Release of Syringyl, Guaiacyl, and Tricin Units

PubMed Central

Gall, Daniel L.; Kontur, Wayne S.; Lan, Wu; Kim, Hoon; Li, Yanding; Ralph, John

2017-01-01

ABSTRACT New environmentally sound technologies are needed to derive valuable compounds from renewable resources. Lignin, an abundant polymer in terrestrial plants comprised predominantly of guaiacyl and syringyl monoaromatic phenylpropanoid units, is a potential natural source of aromatic compounds. In addition, the plant secondary metabolite tricin is a recently discovered and moderately abundant flavonoid in grasses. The most prevalent interunit linkage between guaiacyl, syringyl, and tricin units is the β-ether linkage. Previous studies have shown that bacterial β-etherase pathway enzymes catalyze glutathione-dependent cleavage of β-ether bonds in dimeric β-ether lignin model compounds. To date, however, it remains unclear whether the known β-etherase enzymes are active on lignin polymers. Here we report on enzymes that catalyze β-ether cleavage from bona fide lignin, under conditions that recycle the cosubstrates NAD+ and glutathione. Guaiacyl, syringyl, and tricin derivatives were identified as reaction products when different model compounds or lignin fractions were used as substrates. These results demonstrate an in vitro enzymatic system that can recycle cosubstrates while releasing aromatic monomers from model compounds as well as natural and engineered lignin oligomers. These findings can improve the ability to produce valuable aromatic compounds from a renewable resource like lignin. IMPORTANCE Many bacteria are predicted to contain enzymes that could convert renewable carbon sources into substitutes for compounds that are derived from petroleum. The β-etherase pathway present in sphingomonad bacteria could cleave the abundant β–O–4-aryl ether bonds in plant lignin, releasing a biobased source of aromatic compounds for the chemical industry. However, the activity of these enzymes on the complex aromatic oligomers found in plant lignin is unknown. Here we demonstrate biodegradation of lignin polymers using a minimal set of β-etherase pathway enzymes, the ability to recycle needed cofactors (glutathione and NAD+) in vitro, and the release of guaiacyl, syringyl, and tricin as depolymerized products from lignin. These observations provide critical evidence for the use and future optimization of these bacterial β-etherase pathway enzymes for industrial-level biotechnological applications designed to derive high-value monomeric aromatic compounds from lignin. PMID:29180366

Surface chemistry of aromatic reactants on Pt- and Mo-modified Pt catalysts

DOE PAGES

Robinson, Allison M.; Mark, Lesli; Rasmussen, Mathew J.; ...

2016-11-01

Supported catalysts containing an oxophilic metal such as Mo and a noble metal such as Pt have shown promising activity and selectivity for deoxygenation of biomass-derived compounds. Here, we report that PtMo catalysts also promote hydrogenolysis of the model compound benzyl alcohol, while decarbonylation is most prevalent over unmodified Pt. A combination of single crystal surface science studies, density functional theory (DFT) calculations, and vapor phase upgrading experiments using supported catalysts was carried out to better understand the mechanism by which Mo promotes deoxygenation. Molybdenum was deposited in submonolayer quantities on a Pt(111) surface and reduced at high temperature. Temperature-programmedmore » desorption (TPD) experiments using benzyl alcohol as a reactant showed greatly enhanced yields of the deoxygenation product toluene at moderate Mo coverages. To understand how the interaction of the aromatic group with the surface influenced this reactivity, we investigated the adsorption of toluene as a probe molecule. We found that the addition of Mo to Pt(111) resulted in a significant decrease in toluene decomposition. DFT calculations indicated that this decrease was consistent with decreased aromatic adsorption strengths that accompany incorporation of Mo into the Pt subsurface. The weaker aromatic-surface interaction on Pt/Mo surfaces led to a tilted adsorption geometry for benzyl alcohol, which presumably promotes hydrogenolysis to produce toluene instead of decarbonylation to produce benzene and CO. Alumina-supported Pt and PtMo catalysts were also tested for benzyl alcohol deoxygenation. PtMo catalysts had a higher rate of toluene production and lower rates of benzene and benzaldehyde production. Additionally, when benzaldehyde was used as the reactant to measure decarbonylation activity the mass-normalized rate of benzene production was 2.5 times higher on Pt than PtMo. Altogether, the results of TPD, DFT, and supported catalyst experiments suggest that subsurface Mo sites weaken the binding of aromatic rings on PtMo surfaces; the weakened aromatic-surface interaction is correlated with an improvement in selectivity to C-O bond scission.« less

Synergistic effect of fragrant herbs in Japanese scent sachets.

PubMed

Fujiwara, Yumi; Ito, Michiho

2015-02-01

The sedative activity of eight aromatic natural medicines that are traditionally used in Japanese scent sachets was examined using an open field test with mice. Galangal (Kaempferia galanga), patchouli (Pogostemon cablin), sandalwood (Santalum album), spikenard (Nardostachys chinensis), cinnamon (Cinnamomum cassia), clove (Syzygium aromaticum), star anise (Illicium verum), and borneol (Dryobalanops aromatica) distilled oils were used. These natural medicines have various pharmacological effects. For example, galangal has insecticidal activity and clove extracts possess strong total antioxidant activity. Aromatherapy, a well-known complementary medicine system that uses inhalation, has recently attracted much attention. The sedative activity of inhaled aromatic compounds or essential oils has been examined by measuring the spontaneous motor activity of mice in an open field test. The galangal, patchouli, sandalwood, spikenard, and borneol oils showed significant sedative effects. The effect was stronger for a mixture of the five oils than for any of the single oils. This suggests that the oil mixture may have synergistic activity. Sedative activity was not observed when inactive oils (cinnamon, clove, and star anise) were added to the mixture of the five active oils. Georg Thieme Verlag KG Stuttgart · New York.

Synthesis and antimicrobial activity of novel amphiphilic aromatic amino alcohols.

PubMed

de Almeida, Angelina M; Nascimento, Thiago; Ferreira, Bianca S; de Castro, Pedro P; Silva, Vânia L; Diniz, Claúdio G; Le Hyaric, Mireille

2013-05-15

We report in this work the preparation and in vitro antimicrobial evaluation of novel amphiphilic aromatic amino alcohols synthesized by reductive amination of 4-alkyloxybenzaldehyde with 2-amino-2-hydroxymethyl-propane-1,3-diol. The antibacterial activity was determined against four standard strains (Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Pseudomonas aeruginosa) and 21 clinical isolates of methicillin-resistant Staphylococcus aureus. The antifungal activity was evaluated against four yeast (Candida albicans, Candida tropicalis, Candida glabrata and Candida parapsilosis). The results obtained showed a strong positive correlation between the lipophilicity and the antibiotic activity of the tested compounds. The best activities were obtained against the Gram-positive bacteria (MIC=2-16μgml(-1)) for the five compounds bearing longer alkyl chains (4c-g; 8-14 carbons), which were also the most active against Candida (MIC=2-64μgml(-1)). Compound 4e exhibited the highest levels of inhibitory activity (MIC=2-16μgml(-1)) against clinical isolates of MRSA. A concentration of twice the MIC resulted in bactericidal activity of 4d against 19 of the 21 clinical isolates. Copyright © 2013 Elsevier Ltd. All rights reserved.

Study of improved resins for advanced supersonic technology composites. Part 1: Heteroaromatic polymers containing ether groups. Part 2: Curing chemistry of aromatic polymers and composite studies

NASA Technical Reports Server (NTRS)

Takekoshi, T.; Hillig, W. B.; Mellinger, G. A.

1975-01-01

Fourteen ether-containing, aromatic dianhydrides have been synthesized from N-phenyl-3 or 4-nitrophthalimide and various bisphenols. The process involves nucleophilic displacement of activated nitro groups with bisphenolate ions. Ether-containing dianhydrides were indefinitely stable in the presence of atmospheric moisture. One-step, high temperature solution polymerization of the ether-containing dianhydrides with m-phenylene diamine, 4,4'-oxydianiline and 1, 3-bis(4-aminophenoxy)benzene afforded 42 polyetherimides. The polyetherimides were all soluble in m-cresol except two which were found to be crystalline. The glass transition temperatures of the polyetherimides ranged from 178 to 277 C. Soluble polybenzimidazopyrrolones containing ether groups were also prepared from the same ether-containing dianhydrides and aromatic tetraamines by one-step solution polymerization. Using low molecular weight polyetherimides, various thermoset resin systems were developed and tested as matrices for fiber-reinforced composites. The curing chemistry involving reaction of the phthalonitrile group and the o-diaminophenyl group was found to be generally applicable to crosslinking various aromatic polymers other than polyimides.

Anion-π Catalysts with Axial Chirality.

PubMed

Wang, Chao; Matile, Stefan

2017-09-04

The idea of anion-π catalysis is to stabilize anionic transition states by anion-π interactions on aromatic surfaces. For asymmetric anion-π catalysis, π-acidic surfaces have been surrounded with stereogenic centers. This manuscript introduces the first anion-π catalysts that operate with axial chirality. Bifunctional catalysts with tertiary amine bases next to π-acidic naphthalenediimide planes are equipped with a bulky aromatic substituent in the imide position to produce separable atropisomers. The addition of malonic acid half thioesters to enolate acceptors is used for evaluation. In the presence of a chiral axis, the selective acceleration of the disfavored but relevant enolate addition was much better than with point chirality, and enantioselectivity could be observed for the first time for this reaction with small-molecule anion-π catalysts. Enantioselectivity increased with the π acidity of the π surface, whereas the addition of stereogenic centers around the aromatic plane did not cause further improvements. These results identify axial chirality of the active aromatic plane generated by atropisomerism as an attractive strategy for asymmetric anion-π catalysis. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Aromatic C=C bonds as dipolarophiles: facile reactions of uncomplexed electron-deficient benzene derivatives and other aromatic rings with a non-stabilized azomethine ylide.

PubMed

Lee, Sunyoung; Diab, Sonia; Queval, Pierre; Sebban, Muriel; Chataigner, Isabelle; Piettre, Serge R

2013-05-27

Non-stabilized azomethine ylide 4a reacts smoothly at room temperature with a variety of uncomplexed aromatic heterocycles and carbocycles on the condition that the ring contains at least one or two electron-withdrawing substituents, respectively. Aromatic substrates, including pyridine and benzene derivatives, participate as 2π components in [3+2] cycloaddition reactions and interact with one, two, or three equivalent(s) of the ylide, depending on their structure and substitution pattern. Thus, this process affords highly functionalized polycyclic structures that contain between one and three pyrrolidinyl ring(s) in useful yields. These results indicate that the site selectivity of the cycloaddition reactions strongly depends on both the nature and the positions of the substituents. In most cases, the second 1,3-dipolar reaction occurs on the opposite face to the one that contains the first pyrrolidinyl ring. DFT calculations on model compounds indicate that a concerted mechanism features a low activation barrier. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Controlled field study on the use of nitrate and oxygen for bioremediation of a gasoline source zone

USGS Publications Warehouse

Barbaro, J.R.; Barker, J.F.

2000-01-01

Controlled releases of unleaded gasoline were utilized to evaluate the biotransformation of the soluble aromatic hydrocarbons (benzene, toluene, ethylbenzene, xylene isomers, trimethylbenzene isomers, and naphthalene) within a source zone using nitrate and oxygen as electron acceptors. Experiments were conducted within two 2 m ?? 2 m ?? 3.5 m deep sheet-piling cells. In each treatment cell, a gasoline-contaminated zone was created below the water table. Groundwater amended with electron acceptors was then flushed continuously through the cells for 174 day. Electron-acceptor utilization and hydrocarbon-metabolite formation were noted in both cells, indicating that some microbial activity had been induced in response to flushing. Relative to the cell residence time, nitrate utilization was slow and aromatic-hydrocarbon mass losses in response to microaerophilic dissolved oxygen addition were not obvious under these in situ conditions. There was relatively little biotransformation of the aromatic hydrocarbons over the 2-m flow path monitored in this experiment. A large denitrifying population capable of aromatic hydrocarbon biotransformation failed to develop within the gasoline source zone over a 14-mo period of nitrate exposure.

Factors That Affect Oxygen Activation and Coupling of the Two Redox Cycles in the Aromatization Reaction Catalyzed by NikD, an Unusual Amino Acid Oxidase

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kommoju, Phaneeswara-Rao; Bruckner, Robert C.; Ferreira, Patricia

2009-10-21

NikD is a flavoprotein oxidase that catalyzes the oxidation of piperideine-2-carboxylate (P2C) to picolinate in a remarkable aromatization reaction comprising two redox cycles and at least one isomerization step. Tyr258 forms part of an 'aromatic cage' that surrounds the ring in picolinate and its precursors. Mutation of Tyr258 to Phe does not perturb the structure of nikD but does affect the coupling of the two redox cycles and causes a 10-fold decrease in turnover rate. Tyr258Phe catalyzes a quantitative two-electron oxidation of P2C, but only 60% of the resulting dihydropicolinate intermediate undergoes a second redox cycle to produce picolinate. Themore » mutation does not affect product yield with an alternate substrate (3,4-dehydro-l-proline) that is aromatized in a single two-electron oxidation step. Wild-type and mutant enzymes exhibit identical rate constants for oxidation of P2C to dihydropicolinate and isomerization of a reduced enzyme-dihydropicolinate complex. The observed rates are 200- and 10-fold faster, respectively, than the mutant turnover rate. Release of picolinate from Tyr258Phe is 100-fold faster than turnover. The presence of a bound substrate or product is a key factor in oxygen activation by wild-type nikD, as judged by the 10-75-fold faster rates observed for complexes of the reduced enzyme with picolinate, benzoate, or 1-cyclohexenoate, a 1-deaza-P2C analogue. The reduced Tyr258Phe-1-cyclohexenoate complex is 25-fold less reactive with oxygen than the wild-type complex. We postulate that mutation of Tyr258 causes subtle changes in active site dynamics that promote release of the reactive dihydropicolinate intermediate and disrupt the efficient synchronization of oxygen activation observed with wild-type nikD.« less

Influence of Humic Acids Extracted from Peat by Different Methods on Functional Activity of Macrophages in Vitro.

PubMed

Trofimova, E S; Zykova, M V; Ligacheva, A A; Sherstoboev, E Y; Zhdanov, V V; Belousov, M V; Yusubov, M S; Krivoshchekov, S V; Danilets, M G; Dygai, A M

2017-04-01

We studied activation of macrophages with humic acids extracted from peat of large deposits in the Tomsk region by two extraction methods: by hydroxide or sodium pyrophosphate. Humic acid of lowland peat types containing large amounts of aromatic carbon, phenolic and alcohol groups, carbohydrate residues and ethers, irrespectively of the extraction methods contained LPS admixture that probably determines their activating properties. Humic acid of upland peat types characterized by high content of carbonyl, carboxyl, and ester groups enhance NO production and reduce arginase expression, but these effects were minimized when sodium hydroxide was used as an extraction solvent. Pyrophosphate samples of the upland peat types were characterized by aromaticity and diversity of functional groups and have a significant advantage because of they induce specific endotoxin-independent stimulating action on antigen presenting cells.

Graphene stabilized ultra-small CuNi nanocomposite with high activity and recyclability toward catalysing the reduction of aromatic nitro-compounds

NASA Astrophysics Data System (ADS)

Fang, Hao; Wen, Ming; Chen, Hanxing; Wu, Qingsheng; Li, Weiying

2015-12-01

Nowadays, it is of great significance and a challenge to design a noble-metal-free catalyst with high activity and a long lifetime for the reduction of aromatic nitro-compounds. Here, a 2D structured nanocomposite catalyst with graphene supported CuNi alloy nanoparticles (NPs) is prepared, and is promising for meeting the requirements of green chemistry. In this graphene/CuNi nanocomposite, the ultra-small CuNi nanoparticles (~2 nm) are evenly anchored on graphene sheets, which is not only a breakthrough in the structures, but also brings about an outstanding performance in activity and stability. Combined with a precise optimization of the alloy ratios, the reaction rate constant of graphene/Cu61Ni39 reached a high level of 0.13685 s-1, with a desirable selectivity as high as 99% for various aromatic nitro-compounds. What's more, the catalyst exhibited a unprecedented long lifetime because it could be recycled over 25 times without obvious performance decay or even a morphology change. This work showed the promise and great potential of noble-metal-free catalysts in green chemistry.Nowadays, it is of great significance and a challenge to design a noble-metal-free catalyst with high activity and a long lifetime for the reduction of aromatic nitro-compounds. Here, a 2D structured nanocomposite catalyst with graphene supported CuNi alloy nanoparticles (NPs) is prepared, and is promising for meeting the requirements of green chemistry. In this graphene/CuNi nanocomposite, the ultra-small CuNi nanoparticles (~2 nm) are evenly anchored on graphene sheets, which is not only a breakthrough in the structures, but also brings about an outstanding performance in activity and stability. Combined with a precise optimization of the alloy ratios, the reaction rate constant of graphene/Cu61Ni39 reached a high level of 0.13685 s-1, with a desirable selectivity as high as 99% for various aromatic nitro-compounds. What's more, the catalyst exhibited a unprecedented long lifetime because it could be recycled over 25 times without obvious performance decay or even a morphology change. This work showed the promise and great potential of noble-metal-free catalysts in green chemistry. Electronic supplementary information (ESI) available: Detailed SEM and TEM images, XRD patterns, XPS, EDS, Raman spectra, gas chromatograms, TG analyses, UV-vis spectra, and reaction rate constant tables. See DOI: 10.1039/c5nr05016b

Identification of tyrosine 71 as a critical residue for the cytotoxic activity of Clostridium perfringens epsilon toxin towards MDCK cells.

PubMed

Jiang, Zhigang; Chang, Jitao; Wang, Fang; Yu, Li

2015-02-01

Clostridium perfringens epsilon toxin (Etx) is an extremely potent toxin, causing fatal enterotoxaemia in many animals. Several amino acids in domains I and II have been proposed to be critical for Etx to interact with MDCK cells. However, the critical amino acids in domain III remain undefined. Therefore, we assessed the effects of aromatic amino acids in domain III on Etx activity in this study. All of the results indicated that Y71 was critical for the cytotoxic activity of Etx towards MDCK cells, and this activity was dependent on the existence of an aromatic ring residue in position 71. Additionally, mutations in Y71 did not affect the binding of Etx to MDCK cells, indicating that Y71 is not a receptor binding site for Etx. In summary, we identified an amino acid in domain III that is important for the cytotoxic activity of Etx, thereby providing information on the structure-function relationship of Etx.

Infrared Spectroscopy of Matrix-Isolated Polycyclic Aromatic Compounds and their Ions. 6; Polycyclic Aromatic Nitrogen Heterocycles

NASA Technical Reports Server (NTRS)

Mattioda, A. L.; Hudgins, Douglas M.; Bauschlicher, C. W., Jr.; Rosi, M.; Allamandola, L. J.; DeVincenzi, D. (Technical Monitor)

2002-01-01

The matrix-isolation technique has been employed to measure the mid-infrared spectra of several polycyclic aromatic nitrogen heterocycles in both neutral and cationic forms. The species studied include: 7,8 benzoquinoline (C13H9N); 2-azapyrene (C15H9N); 1- and 2-azabenz(a)anthracene (C17H11N); and 1-, 2-, and 4-azachrysene (also C17H11N). The experimentally measured band frequencies and intensities for each molecule are tabulated and compared with their theoretically calculated values computed using density functional theory at the B3LYP/4-31G level. The overall agreement between experiment and theory is quite good, in keeping with previous investigations involving the parent aromatic hydrocarbons. Several interesting spectroscopic trends are found to accompany nitrogen substitution into the aromatic framework of these compounds. First, for the neutral species, the nitrogen atom produces a significant increase in the total integrated infrared intensity across the 1600 - 1100/cm region and plays an essential role in the molecular vibration that underlies an uncharacteristically intense, discrete feature that is observed near 1400/cm in the spectra of 7,8 benzoquinoline, 1-azabenz(a)anthracene, and 4-azachrysene. The origin of this enhanced infrared activity and the nature of the new 1400/cm vibrational mode are explored. Finally, in contrast to the parent hydrocarbon species, these aromatic nitrogen heterocycles possess a significant permanent dipole moment. Consequently, these dipole moments and the rotational constants are reported for these species in their neutral and ionized forms.

Computational identification of structural factors affecting the mutagenic potential of aromatic amines: study design and experimental validation.

PubMed

Slavov, Svetoslav H; Stoyanova-Slavova, Iva; Mattes, William; Beger, Richard D; Brüschweiler, Beat J

2018-07-01

A grid-based, alignment-independent 3D-SDAR (three-dimensional spectral data-activity relationship) approach based on simulated 13 C and 15 N NMR chemical shifts augmented with through-space interatomic distances was used to model the mutagenicity of 554 primary and 419 secondary aromatic amines. A robust modeling strategy supported by extensive validation including randomized training/hold-out test set pairs, validation sets, "blind" external test sets as well as experimental validation was applied to avoid over-parameterization and build Organization for Economic Cooperation and Development (OECD 2004) compliant models. Based on an experimental validation set of 23 chemicals tested in a two-strain Salmonella typhimurium Ames assay, 3D-SDAR was able to achieve performance comparable to 5-strain (Ames) predictions by Lhasa Limited's Derek and Sarah Nexus for the same set. Furthermore, mapping of the most frequently occurring bins on the primary and secondary aromatic amine structures allowed the identification of molecular features that were associated either positively or negatively with mutagenicity. Prominent structural features found to enhance the mutagenic potential included: nitrobenzene moieties, conjugated π-systems, nitrothiophene groups, and aromatic hydroxylamine moieties. 3D-SDAR was also able to capture "true" negative contributions that are particularly difficult to detect through alternative methods. These include sulphonamide, acetamide, and other functional groups, which not only lack contributions to the overall mutagenic potential, but are known to actively lower it, if present in the chemical structures of what otherwise would be potential mutagens.

Environmental nitration processes enhance the mutagenic potency of aromatic compounds.

PubMed

Bonnefoy, Aurélie; Chiron, Serge; Botta, Alain

2012-05-01

This work is an attempt to establish if aromatic nitration processes are always associated with an increase of genotoxicity. We determined the mutagenic and genotoxic effects of Benzene (B), Nitrobenzene (NB), Phenol (P), 2-Nitrophenol (2-NP), 2,4-Dinitrophenol (2,4-DNP), Pyrene (Py), 1-Nitropyrene (1-NPy), 1,3-Dinitropyrene (1,3-DNPy), 1,6-Dinitropyrene (1,6-DNPy), and 1,8-Dinitropyrene (1,8-DNPy). The mutagenic activities were evaluated with umuC test in presence and in absence of metabolic activation with S9 mix. Then, we used both cytokinesis-blocked micronucleus (CBMN) assay, in combination with fluorescent in situ hybridization (FISH) of human pan-centromeric DNA probes on human lymphocytes in order to evaluate the genotoxic effects. Analysis of all results shows that nitro polycyclic aromatic hydrocarbons (PAHs) are definitely environmental genotoxic/mutagenic hazards and confirms that environmental aromatic nitration reactions lead to an increase in genotoxicity and mutagenicity properties. Particularly 1-NPy and 1,8-DNPy can be considered as human potential carcinogens. They seem to be significant markers of the genotoxicity, mutagenicity, and potential carcinogenicity of complex PAHs mixtures present in traffic emission and industrial environment. In prevention of environmental carcinogenic risk 1-NPy and 1,8-DNPy must therefore be systematically analyzed in environmental complex mixtures in association with combined umuC test, CBMN assay, and FISH on cultured human lymphocytes. © 2010 Wiley Periodicals, Inc. Environ Toxicol, 2012. Copyright © 2010 Wiley Periodicals, Inc.

Select human cancer mutants of NRMT1 alter its catalytic activity and decrease N-terminal trimethylation.

PubMed

Shields, Kaitlyn M; Tooley, John G; Petkowski, Janusz J; Wilkey, Daniel W; Garbett, Nichola C; Merchant, Michael L; Cheng, Alan; Schaner Tooley, Christine E

2017-08-01

A subset of B-cell lymphoma patients have dominant mutations in the histone H3 lysine 27 (H3K27) methyltransferase EZH2, which change it from a monomethylase to a trimethylase. These mutations occur in aromatic resides surrounding the active site and increase growth and alter transcription. We study the N-terminal trimethylase NRMT1 and the N-terminal monomethylase NRMT2. They are 50% identical, but differ in key aromatic residues in their active site. Given how these residues affect EZH2 activity, we tested whether they are responsible for the distinct catalytic activities of NRMT1/2. Additionally, NRMT1 acts as a tumor suppressor in breast cancer cells. Its loss promotes oncogenic phenotypes but sensitizes cells to DNA damage. Mutations of NRMT1 naturally occur in human cancers, and we tested a select group for altered activity. While directed mutation of the aromatic residues had minimal catalytic effect, NRMT1 mutants N209I (endometrial cancer) and P211S (lung cancer) displayed decreased trimethylase and increased monomethylase/dimethylase activity. Both mutations are located in the peptide-binding channel and indicate a second structural region impacting enzyme specificity. The NRMT1 mutants demonstrated a slower rate of trimethylation and a requirement for higher substrate concentration. Expression of the mutants in wild type NRMT backgrounds showed no change in N-terminal methylation levels or growth rates, demonstrating they are not acting as dominant negatives. Expression of the mutants in cells lacking endogenous NRMT1 resulted in minimal accumulation of N-terminal trimethylation, indicating homozygosity could help drive oncogenesis or serve as a marker for sensitivity to DNA damaging chemotherapeutics or γ-irradiation. © 2017 The Protein Society.

Natural Mediators in the Oxidation of Polycyclic Aromatic Hydrocarbons by Laccase Mediator Systems

PubMed Central

Johannes, Christian; Majcherczyk, Andrzej

2000-01-01

The oxidation of polycyclic aromatic compounds was studied in systems consisting of laccase from Trametes versicolor and so-called mediator compounds. The enzymatic oxidation of acenaphthene, acenaphthylene, anthracene, and fluorene was mediated by various laccase substrates (phenols and aromatic amines) or compounds produced and secreted by white rot fungi. The best natural mediators, such as phenol, aniline, 4-hydroxybenzoic acid, and 4-hydroxybenzyl alcohol were as efficient as the previously described synthetic compounds ABTS [2,2′-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid)] and 1-hydroxybenzotriazole. The oxidation efficiency increased proportionally with the redox potentials of the phenolic mediators up to a maximum value of 0.9 V and decreased thereafter with redox potentials exceeding this value. Natural compounds such as methionine, cysteine, and reduced glutathione, containing sulfhydryl groups, were also active as mediator compounds. PMID:10653713

Nucleophilic fluorination of aromatic compounds

DOEpatents

Satyamurthy, Nagichettiar; Barrio, Jorge R

2014-03-18

Iodylbenzene derivatives substituted with electron donating as well as electron withdrawing groups on the aromatic ring are used as precursors in aromatic nucleophilic substitution reactions. The iodyl group (IO.sub.2) is regiospecifically substituted by nucleophilic fluoride to provide the corresponding fluoroaryl derivatives. No-carrier-added [F-18]fluoride ion derived from anhydrous [F-18](F/Kryptofix, [F-18]CsF or a quaternary ammonium fluoride (e.g., Me.sub.4NF, Et.sub.4NF, n-Bu.sub.4NF, (PhCH.sub.2).sub.4NF) exclusively substitutes the iodyl moiety in these derivatives and provides high specific activity F-18 labeled fluoroaryl analogs. Iodyl derivatives of a benzothiazole analog and 6-iodyl-L-dopa derivatives have been synthesized as precursors and have been used in the preparation of no-carrier-added [F-18]fluorobenzothiazole as well as 6-[F-18]fluoro-L-dopa.

The Effect of Kaffir Lime Leaves Distillation Residue Oleoresin Concentration on Active Paper Packaging Characteristics

NASA Astrophysics Data System (ADS)

Kawiji; Utami, R.; Ulum, S.; Khasanah, L. U.; Manuhara, G. J.; Atmaka, W.

2018-03-01

Oleoresin of kaffir lime leaves distillation residue still contains some active compounds such as Citronellal, β-Citronellol, and Linalool which potential to incorporated on the active paper packaging. The purposes of this study were to determine the effect of kaffir lime leaves distillation residue oleoresin concentration on the physical characteristics, sensory characteristics, and antimicrobial activity of the active paper packaging incorporated with kaffir lime leaves distillation residue oleoresin and to determine the functional groups of active paper packaging. The concentration of kaffir lime leaves distillation residue oleoresin were varied at 0%, 2%, 4% and 6%. The result showed that the addition of kaffir lime leaves distillation residue oleoresin increased the thickness and moisture content of the paper and decreased the tensile strengths and folding endurances of active paper packaging. The microbial inhibition tends to increase along with the higher oleoresin concentration addition. Aromatic CH group were found at a wavelength of 897.90 cm-1 of on paper packaging with 2% oleoresin indicated as functional aromatic functional group allegedly obtained from the kaffir lime leaves oleoresin.

Inhibitors of calling behavior of Plodia interpunctella.

PubMed

Hirashima, Akinori; Shigeta, Yoko; Eiraku, Tomohiko; Kuwano, Eiichi

2003-01-01

Some octopamine agonists were found to suppress the calling behavior of the stored product Indian meal moth, Plodia interpunctella. Compounds were screened using a calling behavior bioassay using female P. interpunctella. Four active derivatives, with inhibitory activity at the nanomolar range, were identified in order of decreasing activity: 2-(1-phenylethylamino)-2-oxazoline > 2-(2-ethyl,6-methylanilino)oxazolidine > 2-(2-methyl benzylamino)-2-thiazoline > 2-(2,6-diethylanilino)thiazolidine. Three-dimensional pharmacophore hypotheses were built from a set of 15 compounds. Among the ten common-featured models generated by the program Catalyst/HipHop, a hypothesis including a hydrogen-bond acceptor lipid, a hydrophobic aromatic and two hydrophobic aliphatic features was considered to be essential for inhibitory activity in the calling behavior. Active compounds mapped well onto all the hydrogen-bond acceptor lipid, hydrophobic aromatic and hydrophobic aliphatic features of the hypothesis. On the other hand, less active compounds were shown not to achieve the energetically favorable conformation that is found in the active molecules in order to fit the 3D common-feature pharmacophore models. The present studies demonstrate that inhibition of calling behavior is via an octopamine receptor.

Chlorination of humic materials: Byproduct formation and chemical interpretations

USGS Publications Warehouse

Reckhow, D.A.; Singer, P.C.; Malcolm, R.L.

1990-01-01

Ten aquatic humic and fulvic acids were isolated and studied with respect to their reaction with chlorine. Yields of TOX, chloroform, trichloroacetic acid, dichloroacetic acid, dichloroacetonitrile, and 1,1,1-trichloropropanone were measured at pH 7 and 12. Humic acids produced higher concentrations than their corresponding fulvic acids of all byproducts except 1,1,1-trichloropropanone. Chlorine consumption and byproduct formation were related to fundamental chemical characteristics of the humic materials. A statistical model was proposed for activated aromatic content based on 13C NMR and base titration data. The values estimated from this model were found to be well correlated with chlorine consumption. Specific byproduct formation was related to UV absorbance, nitrogen content, or the activated aromatic content. ?? 1990 American Chemical Society.

Search for β-Secretase Inhibitors from Natural Spices.

PubMed

Matsumura, Shinichi; Murata, Kazuya; Yoshioka, Yuri; Matsuda, Hideaki

2016-04-01

The growing number of Alzheimer's disease (AD) patients prompted us to seek effective natural resources for the prevention of AD. We focused on the inhibition of β-secretase, which is known to catalyze the production of senile plaque. Sixteen spices used in Asian countries were selected for the screening. Among the extracts tested, hexane extracts obtained from turmeric, cardamom, long pepper, cinnamon, Sichuan pepper, betel, white turmeric and aromatic ginger showed potent inhibitory activities. Their active principles were identified as sesquiterpenoids, monoterpenoids, fatty acid derivatives and phenylpropanoids using GC-MS analyses. The chemical structures and IC50 values of the compounds are disclosed. The results suggest that long-term consumption'of aromatic compounds from spices could be effective in the prevention of AD.

Microbial degradation and toxicity of hexahydro-1,3,5-trinitro-1,3,5-triazine.

PubMed

Khan, Muhammad Imran; Lee, Jaejin; Park, Joonhong

2012-10-01

In the present work, current knowledge on the potential fate, microbial degradation, and toxicity of hexahydro- 1,3,5-trinitro-1,3,5-triazine (RDX) was thoroughly reviewed, focusing on the toxicological assessment of a variety of potential RDX degradation pathways in bacteria and fungi. The present review on microbial degradation pathways and toxicities of degradation intermediates suggests that, among aerobic RDX degradation pathways, the one via denitration may be preferred in a toxicological perspective, and that among anaerobic pathways, those forming 4- nitro-2,4-diazabutanal (NDAB) via ring cleavage of 1-nitroso- 3,5-dinitro-1,3,5-triazinane (MNX) may be toxicologically advantageous owing to its potential mineralization under partial or complete anoxic conditions. These findings provide important information on RDX-degrading microbial pathways, toxicologically most suitable to be stimulated in contaminated fields.

Health hazard evaluation report HETA 80-008-1546, BASF Wyandotte Corporation, Rensselaer, New York

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gordon, J.E.; Taylor, P.; Hearn, S.

A health hazard evaluation at BASF Wyandotte Corporation (SIC-2810, SIC-2820, SIC-2880, SIC-2870), Rensselaer, New York was conducted. The evaluation was requested by a union representative because of adverse pregnancy outcomes among workers involved in the manufacture of 3,5-dinitro-N-4N-4-dipropylsulfanilamide (19044883) (oryzalin). All persons employed from January 1, 1972 through December 31, 1980 were identified from company records. Birth, fetal, and death records were obtained from the State of New York. The authors conclude that workers who were involved in manufacturing oryzalin sired offspring having an unusual cluster of birth defects, especially those of the heart. Whether these were the result ofmore » occupational exposure cannot be decisively determined. Implementing proper engineering and work practice controls is recommended.« less

Determination of 2-isovaleryl-1,3-indandione with 2, 4-dinitro-phenylhydrazine

USGS Publications Warehouse

Menzie, C.M.; Adomaitis, V.A.; Reichel, W.L.

1962-01-01

At present, three 2-alkyl-1,3-indandiones (PMP, pival, and diphacinon) are widely used as rodenticides. Because analytical procedures now in use are empirical and do not furnish adequate or positive means for distinguishing among these closely related compounds, studies were undertaken to develop a sensitive and specific method for the determination of PMP. The relation between KCN and the 2,4-dinitrophenylhydrazone of PMP was investigated and shown to be sensitive and specific. A deeply colored solution is produced with an absorption maximum at 540 mu. This solution obeys Beer?s law over a wide range. The molar absorptivity for the developed color was calculated to be 3.0 X 104. This reaction can be used also as a spot test to detect as little as 1 ug. of PMP.

Role of Pt during hydrodeoxygenation of biomass pyrolysis vapors over Pt/HBEA

DOE PAGES

Yung, Matthew M.; Foo, Guo Shiou; Sievers, Carsten

2017-03-27

1.3 wt% Pt/HBEA and HBEA were studied as catalysts for the hydrodeoxygenation of pine pyrolysis vapors at 500 °C. Both catalysts showed high initial conversion of oxygenated pyrolysis products into aromatic hydrocarbons, while Pt/HBEA showed higher stability in terms of hydrocarbon productivity and deferred breakthrough of oxygenated compounds. Among 1-, 2- and 3-ring aromatic hydrocarbons, Pt/HBEA had a significantly higher selectivity than HBEA towards unalkylated aromatics (e.g., benzene) as compared to the corresponding alkylated aromatics (e.g., toluene and xylene). Additionally, Pt addition to HBEA decreased coke deposition and improved resistance to pore and acid site blockage as determined by TPO,more » N 2 physisorption, and NH 3 TPD. The ability of Pt to promote cleavage and hydrogenation of methoxy and methyl groups was observed by increased methane production over Pt/HBEA relative to HBEA. A progressive decrease in the methane production over Pt/HBEA correlated with deactivation in terms of reduced benzene formation, breakthrough of oxygenated products, and increased formation of polynuclear aromatics and their degree of substitution, which indicate coke formation. In conclusion, the increased methane yield and suppressed coke formation with the addition of Pt is attributed to hydrogen spillover, through which hydrogen activated on Pt can subsequently migrate to the HBEA support to reverse the coke-forming hydrogen abstraction reaction.« less

Role of Pt during hydrodeoxygenation of biomass pyrolysis vapors over Pt/HBEA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yung, Matthew M.; Foo, Guo Shiou; Sievers, Carsten

1.3 wt% Pt/HBEA and HBEA were studied as catalysts for the hydrodeoxygenation of pine pyrolysis vapors at 500 °C. Both catalysts showed high initial conversion of oxygenated pyrolysis products into aromatic hydrocarbons, while Pt/HBEA showed higher stability in terms of hydrocarbon productivity and deferred breakthrough of oxygenated compounds. Among 1-, 2- and 3-ring aromatic hydrocarbons, Pt/HBEA had a significantly higher selectivity than HBEA towards unalkylated aromatics (e.g., benzene) as compared to the corresponding alkylated aromatics (e.g., toluene and xylene). Additionally, Pt addition to HBEA decreased coke deposition and improved resistance to pore and acid site blockage as determined by TPO,more » N 2 physisorption, and NH 3 TPD. The ability of Pt to promote cleavage and hydrogenation of methoxy and methyl groups was observed by increased methane production over Pt/HBEA relative to HBEA. A progressive decrease in the methane production over Pt/HBEA correlated with deactivation in terms of reduced benzene formation, breakthrough of oxygenated products, and increased formation of polynuclear aromatics and their degree of substitution, which indicate coke formation. In conclusion, the increased methane yield and suppressed coke formation with the addition of Pt is attributed to hydrogen spillover, through which hydrogen activated on Pt can subsequently migrate to the HBEA support to reverse the coke-forming hydrogen abstraction reaction.« less

Palladium-catalysed electrophilic aromatic C-H fluorination

NASA Astrophysics Data System (ADS)

Yamamoto, Kumiko; Li, Jiakun; Garber, Jeffrey A. O.; Rolfes, Julian D.; Boursalian, Gregory B.; Borghs, Jannik C.; Genicot, Christophe; Jacq, Jérôme; van Gastel, Maurice; Neese, Frank; Ritter, Tobias

2018-02-01

Aryl fluorides are widely used in the pharmaceutical and agrochemical industries, and recent advances have enabled their synthesis through the conversion of various functional groups. However, there is a lack of general methods for direct aromatic carbon-hydrogen (C-H) fluorination. Conventional methods require the use of either strong fluorinating reagents, which are often unselective and difficult to handle, such as elemental fluorine, or less reactive reagents that attack only the most activated arenes, which reduces the substrate scope. A method for the direct fluorination of aromatic C-H bonds could facilitate access to fluorinated derivatives of functional molecules that would otherwise be difficult to produce. For example, drug candidates with improved properties, such as increased metabolic stability or better blood-brain-barrier penetration, may become available. Here we describe an approach to catalysis and the resulting development of an undirected, palladium-catalysed method for aromatic C-H fluorination using mild electrophilic fluorinating reagents. The reaction involves a mode of catalysis that is unusual in aromatic C-H functionalization because no organometallic intermediate is formed; instead, a reactive transition-metal-fluoride electrophile is generated catalytically for the fluorination of arenes that do not otherwise react with mild fluorinating reagents. The scope and functional-group tolerance of this reaction could provide access to functional fluorinated molecules in pharmaceutical and agrochemical development that would otherwise not be readily accessible.

Comprehensive review on toxicity of persistent organic pollutants from petroleum refinery waste and their degradation by microorganisms.

PubMed

Varjani, Sunita J; Gnansounou, Edgard; Pandey, Ashok

2017-12-01

Control and prevention of environmental pollution has become a worldwide issue of concern. Aromatic hydrocarbons including benzene, toluene, ethyl benzene, xylene (BTEX) and polyaromatic hydrocarbons (PAHs) are persistent organic pollutants (POPs), released into the environment mainly by exploration activities of petroleum industry. These pollutants are mutagenic, carcinogenic, immunotoxic and teratogenic to lower and higher forms of life i.e. microorganisms to humans. According to the International Agency for Research on Cancer (IARC) and United States Environmental Protection Agency (U.S. EPA), Benzo[a]pyrene (BaP) is carcinogenic in laboratory animals and humans. Aromatic hydrocarbons are highly lipid soluble and thus readily absorbed from environment in gastrointestinal tract of mammals. Treatment and remediation of petroleum refinery waste have been shown either to reduce or to eliminate genotoxicity of these pollutants. Bioremediation by using microorganisms to treat this waste is showing a promising technology as it is safe and cost-effective option among various technologies tested. The main aim of this review is to provide contemporary information on variety of aromatic hydrocarbons present in crude oil (with special focus to mono- and poly-aromatic hydrocarbons), exposure routes and their adverse effects on humans. This review also provides a synthesis of scientific literature on remediation technologies available for aromatic hydrocarbons, knowledge gaps and future research developments in this field. Copyright © 2017 Elsevier Ltd. All rights reserved.

Chemical constituents of Swertia longifolia Boiss. with α-amylase inhibitory activity.

PubMed

Saeidnia, Soodabeh; Ara, Leila; Hajimehdipoor, Homa; Read, Roger W; Arshadi, Sattar; Nikan, Marjan

2016-01-01

α-Amylase inhibitors play a critical role in the control of diabetes and many of medicinal plants have been found to act as α-amylase inhibitors. Swertia genus, belonging to the family Gentianaceae, comprises different species most of which have been used in traditional medicine of several cultures as antidiabetic, anti-pyretic, analgesic, liver and gastrointestinal tonic. Swertia longifolia Boiss. is the only species of Swertia growing in Iran. In the present investigation, phytochemical study of S. longifolia was performed and α-amylase inhibitory effects of the plant fractions and purified compounds were determined. Aerial parts of the plant were extracted with hexane, chloroform, methanol and water, respectively. The components of the hexane and chloroform fractions were isolated by different chromatographic methods and their structures were determined by (1)H NMR and (13)C NMR data. α-Amylase inhibitory activity was determined by a colorimetric assay using 3,5-dinitro salysilic acid. During phytochemical examination, α-amyrin, β-amyrin and β-sitosterol were purified from the hexane fraction, while ursolic acid, daucosterol and swertiamarin were isolated from chloroform fraction. The results of the biochemical assay revealed α-amylase inhibitory activity of hexane, chloroform, methanol and water fractions, of which the chloroform and methanol fractions were more potent (IC50 16.8 and 18.1 mg/ml, respectively). Among examined compounds, daucosterol was found to be the most potent α-amylase inhibitor (57.5% in concentration 10 mg/ml). With regard to α-amylase inhibitory effects of the plant extracts, purified constituents, and antidiabetic application of the species of Swertia genus in traditional medicine of different countries, S. longifolia seems more appropriate species for further mechanistic antidiabetic evaluations.

Chemical constituents of Swertia longifolia Boiss. with α-amylase inhibitory activity

PubMed Central

Saeidnia, Soodabeh; Ara, Leila; Hajimehdipoor, Homa; Read, Roger W.; Arshadi, Sattar; Nikan, Marjan

2016-01-01

α-Amylase inhibitors play a critical role in the control of diabetes and many of medicinal plants have been found to act as α-amylase inhibitors. Swertia genus, belonging to the family Gentianaceae, comprises different species most of which have been used in traditional medicine of several cultures as antidiabetic, anti-pyretic, analgesic, liver and gastrointestinal tonic. Swertia longifolia Boiss. is the only species of Swertia growing in Iran. In the present investigation, phytochemical study of S. longifolia was performed and α-amylase inhibitory effects of the plant fractions and purified compounds were determined. Aerial parts of the plant were extracted with hexane, chloroform, methanol and water, respectively. The components of the hexane and chloroform fractions were isolated by different chromatographic methods and their structures were determined by 1H NMR and 13C NMR data. α-Amylase inhibitory activity was determined by a colorimetric assay using 3,5-dinitro salysilic acid. During phytochemical examination, α-amyrin, β-amyrin and β-sitosterol were purified from the hexane fraction, while ursolic acid, daucosterol and swertiamarin were isolated from chloroform fraction. The results of the biochemical assay revealed α-amylase inhibitory activity of hexane, chloroform, methanol and water fractions, of which the chloroform and methanol fractions were more potent (IC50 16.8 and 18.1 mg/ml, respectively). Among examined compounds, daucosterol was found to be the most potent α-amylase inhibitor (57.5% in concentration 10 mg/ml). With regard to α-amylase inhibitory effects of the plant extracts, purified constituents, and antidiabetic application of the species of Swertia genus in traditional medicine of different countries, S. longifolia seems more appropriate species for further mechanistic antidiabetic evaluations. PMID:27051429

Studies on non-steroidal inhibitors of aromatase enzyme; 4-(aryl/heteroaryl)-2-(pyrimidin-2-yl)thiazole derivatives.

PubMed

Sahin, Zafer; Ertas, Merve; Berk, Barkın; Biltekin, Sevde Nur; Yurttas, Leyla; Demirayak, Seref

2018-05-01

Steroidal and non-steroidal aromatase inhibitors target the suppression of estrogen biosynthesis in the treatment of breast cancer. Researchers have increasingly focused on developing non-steroidal derivatives for their potential clinical use avoiding steroidal side-effects. Non-steroidal derivatives generally have planar aromatic structures attached to the azole ring system. One part of this ring system comprises functional groups that inhibit aromatization through the coordination of the haem group of the aromatase enzyme. Replacement of the triazole ring system and development of aromatic/cyclic structures of the side chain can increase selectivity over aromatase enzyme inhibition. In this study, 4-(aryl/heteroaryl)-2-(pyrimidin-2-yl)thiazole derivatives were synthesized and physical analyses and structural determination studies were performed. The IC 50 values were determined by a fluorescence-based aromatase inhibition assay and compound 1 (4-(2-hydroxyphenyl)-2-(pyrimidine-2-yl)thiazole) were found potent inhibitor of enzyme (IC 50 :0.42 nM). Then, their antiproliferative activity over MCF-7 and HEK-293 cell lines was evaluated using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Compounds 1, 7, 8, 13, 15, 18, 21 were active against MCF-7 breast cancer cells. Lastly, a series of docking experiments were undertaken to analyze the crystal structure of human placental aromatase and identify the possible interactions between the most active structure and the active site. Copyright © 2018 Elsevier Ltd. All rights reserved.

Friedel-Crafts Acylation with Amides

PubMed Central

Raja, Erum K.; DeSchepper, Daniel J.; Nilsson Lill, Sten O.; Klumpp, Douglas A.

2012-01-01

Friedel-Crafts acylation has been known since the 1870s and it is an important organic synthetic reaction leading to aromatic ketone products. Friedel-Crafts acylation is usually done with carboxylic acid chlorides or anhydrides while amides are generally not useful substrates in these reactions. Despite being the least reactive carboxylic acid derivative, we have found a series of amides capable of providing aromatic ketones in good yields (55–96%, 17 examples). We propose a mechanism involving diminished C-N resonance through superelectrophilic activation and subsequent cleavage to acyl cations. PMID:22690740

Mineralization of polycyclic aromatic hydrocarbons by the white rot fungus Pleurotus ostreatus

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bezalel, L.; Hadar, Y.; Cerniglia, C.E.

White rot fungi, including Pleurotus ostreatus, have the ability to efficiently degrade lignin, a naturally occurring aromatic polymer. Previous work has found these organisms were able to degrade PAHs and in some cases to mineralize them; most of the work was done with Phanerochaete chrysosporium. P. ostreatus differs from P. chrysosporium in its lignin degradation mechanism. In this study, enzymatic activities were monitored during P. ostreatus growth in the presence of PAHs and the fungus`s ability to mineralize catechol and various PAHs was demonstrated. 29 refs., 3 figs., 1 tab.

Effects of Volatile Aromatic Anesthetics on Voltage-Gated Na+ Channels Expressed in Xenopus Oocytes

PubMed Central

Horishita, Takafumi; Eger, Edmond I; Harris, R. Adron

2008-01-01

Background Many inhaled anesthetics inhibit voltage-gated sodium channels at clinically relevant concentrations, and suppression of neurotransmitter release by these agents results, at least partly, from decreased presynaptic sodium channel activity. Volatile aromatic anesthetics can inhibit N-methyl-D-aspartate (NMDA) receptor function and enhance γ-amino butyric acid A (GABAA) receptor function, but these effects depend strongly on the chemical properties of the aromatic ompounds. The present study tested whether diverse aromatic anesthetics consistently inhibit sodium channel function. Methods We studied the effect of eight aromatic anesthetics on Nav1.2 sodium channels with β1 subunits, using whole-cell, two-electrode voltage-clamp techniques in Xenopus oocytes. Results All aromatic anesthetics inhibited INa (sodium currents) at a holding potential which produce half-maximal current (V1/2) (partial depolarization); inhibition was modest with 1,3,5-trifluorobenzene (8 ± 2%), pentafluorobenzene (13 ± 2%), and hexafluorobenzene (13 ± 2%), but greater with benzene (37 ± 2%), fluorobenzene (39 ± 2%), 1,2-difluorobenzene (48 ± 2%), 1,4-difluorobenzene (31 ± 3%), and 1,2,4-trifluorobenzene (33 ± 1%). Such dichotomous effects were noted by others for NMDA and GABAA receptors. Parallel, but much smaller inhibition, was found for INa at a holding potential which produced near maximal current (−90 mV) (VH-90), and hexafluorobenzene caused small (6 ± 1%) potentiation of this current. These changes in sodium channel function were correlated with effectiveness for inhibiting NMDA receptors, with lipid solubility of the compounds, with molecular volume, and with cation-π interactions. Conclusion Aromatic compounds vary in their actions on the kinetics of sodium channel gating and this may underlie their variable inhibition. The range of inhibition produced by MAC concentrations of inhaled anesthetics indicates that sodium channel inhibition may underlie the action of some of these anesthetics but not others. PMID:18931215

Elastomer Impact When Switch-Loading Synthetic Fuel Blends and Petroleum Fuels

DTIC Science & Technology

2006-07-01

aromatics by ASTM D 5186 ( supercrital Fluid Chromatography method used for aromatics) in reference 4, was assumed to be equivalent to volume percent...Included in Appendix C is the internet link to the datasheets for the aromatic surrogate, Aromatic 150 Fluid . Characterizations of this aromatic...www.exxonmobilchemical.com/Public_Products/ Fluids /Aromatics_HeavyAromatics/Worldwi de/Grades_and_DataSheets/Aro_HeavyAromatics_Solvesso_Grades_WW.asp 21

Identification of cancer chemopreventive isothiocyanates as direct inhibitors of the arylamine N-acetyltransferase-dependent acetylation and bioactivation of aromatic amine carcinogens.

PubMed

Duval, Romain; Xu, Ximing; Bui, Linh-Chi; Mathieu, Cécile; Petit, Emile; Cariou, Kevin; Dodd, Robert H; Dupret, Jean-Marie; Rodrigues-Lima, Fernando

2016-02-23

Aromatic amines (AAs) are chemicals of industrial, pharmacological and environmental relevance. Certain AAs, such as 4-aminobiphenyl (4-ABP), are human carcinogens that require enzymatic metabolic activation to reactive chemicals to form genotoxic DNA adducts. Arylamine N-acetyltransferases (NAT) are xenobiotic metabolizing enzymes (XME) that play a major role in this carcinogenic bioactivation process. Isothiocyanates (ITCs), including benzyl-ITC (BITC) and phenethyl-ITC (PEITC), are phytochemicals known to have chemopreventive activity against several aromatic carcinogens. In particular, ITCs have been shown to modify the bioactivation and subsequent mutagenicity of carcinogenic AA chemicals such as 4-ABP. However, the molecular and biochemical mechanisms by which these phytochemicals may modulate AA carcinogens bioactivation and AA-DNA damage remains poorly understood. This manuscript provides evidence indicating that ITCs can decrease the metabolic activation of carcinogenic AAs via the irreversible inhibition of NAT enzymes and subsequent alteration of the acetylation of AAs. We demonstrate that BITC and PEITC react with NAT1 and inhibit readily its acetyltransferase activity (k(i) = 200 M(-1).s(-1) and 66 M(-1).s(-1) for BITC and PEITC, respectively). Chemical labeling, docking approaches and substrate protection assays indicated that inhibition of the acetylation of AAs by NAT1 was due to the chemical modification of the enzyme active site cysteine. Moreover, analyses of AAs acetylation and DNA adducts in cells showed that BITC was able to modulate the endogenous acetylation and bioactivation of 4-ABP. In conclusion, we show that direct inhibition of NAT enzymes may be an important mechanism by which ITCs exert their chemopreventive activity towards AA chemicals.

Bifunctional Molybdenum Polyoxometalates for the Combined Hydrodeoxygenation and Alkylation of Lignin-Derived Model Phenolics.

PubMed

Anderson, Eric; Crisci, Anthony; Murugappan, Karthick; Román-Leshkov, Yuriy

2017-05-22

Reductive catalytic fractionation of biomass has recently emerged as a powerful lignin extraction and depolymerization method to produce monomeric aromatic oxygenates in high yields. Here, bifunctional molybdenum-based polyoxometalates supported on titania (POM/TiO 2 ) are shown to promote tandem hydrodeoxygenation (HDO) and alkylation reactions, converting lignin-derived oxygenated aromatics into alkylated benzenes and alkylated phenols in high yields. In particular, anisole and 4-propylguaiacol were used as model compounds for this gas-phase study using a packed-bed flow reactor. For anisole, 30 % selectivity for alkylated aromatic compounds (54 % C-alkylation of the methoxy groups by methyl balance) with an overall 72 % selectivity for HDO at 82 % anisole conversion was observed over H 3 PMo 12 O 40 /TiO 2 at 7 h on stream. Under similar conditions, 4-propylguaiacol was mainly converted into 4-propylphenol and alkylated 4-propylphenols with a selectivity to alkylated 4-propylphenols of 42 % (77 % C-alkylation) with a total HDO selectivity to 4-propylbenzene and alkylated 4-propylbenzenes of 4 % at 92 % conversion (7 h on stream). Higher catalyst loadings pushed the 4-propylguaiacol conversion to 100 % and resulted in a higher selectivity to propylbenzene of 41 %, alkylated aromatics of 21 % and alkylated phenols of 17 % (51 % C-alkylation). The reactivity studies coupled with catalyst characterization revealed that Lewis acid sites act synergistically with neighboring Brønsted acid sites to simultaneously promote alkylation and hydrodeoxygenation activity. A reaction mechanism is proposed involving activation of the ether bond on a Lewis acid site, followed by methyl transfer and C-alkylation. Mo-based POMs represent a versatile catalytic platform to simultaneously upgrade lignin-derived oxygenated aromatics into alkylated arenes. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

The active analog approach applied to the pharmacophore identification of benzodiazepine receptor ligands

NASA Astrophysics Data System (ADS)

Tebib, Souhail; Bourguignon, Jean-Jacques; Wermuth, Camille-Georges

1987-07-01

Applied to seven potent benzodiazepine-receptor ligands belonging to chemically different classes, the active analog approach allowed the stepwise identification of the pharmacophoric pattern associated with the recognition by the benzodiazepine receptor. A unique pharmacophore model was derived which involves six critical zones: (a) a π-electron rich aromatic (PAR) zone; (b) two electron-rich zones δ1 and δ2 placed at 5.0 and 4.5 Å respectively from the reference centroid in the PAR zone; (c) a freely rotating aromatic ring (FRA) region; (d) an out-of-plane region (OPR), strongly associated with agonist properties; and (e) an additional hydrophobic region (AHR). The model accommodates all presently known ligands of the benzodiazepine receptor, identifies sensitivity to steric hindrance close to the δ1 zone, accounts for R and S differential affinities and distinguishes requirements for agonist versus non-agonist activity profiles.

Potential application of aromatic plant extracts to prevent cheese blowing.

PubMed

Librán, C M; Moro, A; Zalacain, A; Molina, A; Carmona, M; Berruga, M I

2013-07-01

This study aimed to inhibit the growth of Escherichia coli and Clostridium tyrobutyricum, common bacteria responsible for early and late cheese blowing defects respectively, by using novel aqueous extracts obtained by dynamic solid-liquid extraction and essential oils obtained by solvent free microwave extraction from 12 aromatic plants. In terms of antibacterial activity, a total of 13 extracts inhibited one of the two bacteria, and only two essential oils, Lavandula angustifolia Mill. and Lavandula hybrida, inhibited both. Four aqueous extracts were capable of inhibiting C. tyrobutyricum, but none were effective against E. coli. After extracts' chemical composition identification, relationship between the identified compounds and their antibacterial activity were performed by partial least square regression models revealing that compounds such as 1,8 cineole, linalool, linalyl acetate, β-phellandrene or verbene (present in essential oils), pinocarvone, pinocamphone or coumaric acid derivate (in aqueous extracts) were compounds highly correlated to the antibacterial activity.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tahir, Dahlang, E-mail: dtahir@fmipa.unhas.ac.id; Bakri, Fahrul; Liong, Syarifuddin

We have studied the molecular properties, structural properties, and chemical composition of composites by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) spectroscopy, and X-ray fluorescence (XRF) spectroscopy, respectively. FTIR spectra shows absorption band of hydroxyl group (-OH), methyl group (-CH{sub 3}) and aromatic group (C-C). The absorption band for aromatic group (C-C) shows the formation of carbonaceous in composites. XRF shows chemical composition of composites, which the main chemicals are SO{sub 3}, Cl, and ZnO. The loss on ignition value (LOI) of activated charcoal indicates high carbonaceous matter. The crystallite size for diffraction pattern from hydrogel polymer is aboutmore » 17 nm and for activated charcoal are about 19 nm. The crystallite size of the polymer is lower than that of activated charcoal, which make possible of the particle from filler in contact with each other to form continuous conducting polymer through polymer matrix.« less

Rational engineering of the fungal P450 monooxygenase CYP5136A3 to improve its oxidizing activity toward polycyclic aromatic hydrocarbons.

PubMed

Syed, Khajamohiddin; Porollo, Aleksey; Miller, David; Yadav, Jagjit S

2013-09-01

A promising polycyclic aromatic hydrocarbon-oxidizing P450 CYP5136A3 from Phanerochaete chrysosporium was rationally engineered to enhance its catalytic activity. The residues W129 and L324 found to be critical in substrate recognition were transformed by single (L324F) and double (W129L/L324G, W129L/L324F, W129A/L324G, W129F/L324G and W129F/L324F) mutations, and the engineered enzyme forms were expressed in Pichia pastoris. L324F and W129F/L324F mutations enhanced the oxidation activity toward pyrene and phenanthrene. L324F also altered the regio-selectivity favoring C position 4 over 9 for hydroxylation of phenanthrene. This is the first instance of engineering a eukaryotic P450 for enhanced oxidation of these fused-ring hydrocarbons.

Augmenting the activity of antifungal agents against aspergilli using structural analogues of benzoic acid as chemosensitizing agents

USDA-ARS?s Scientific Manuscript database

Structure-activity analysis revealed that antifungal activities of benzoic and gallic acids were increased against strains of Aspergillus flavus, A. fumigatus and A. terreus, causative agents of human aspergillosis, by addition of a methyl, methoxyl or a chloro group at position 4 of the aromatic ri...

Discovery of unsymmetrical aromatic disulfides as novel inhibitors of SARS-CoV main protease: Chemical synthesis, biological evaluation, molecular docking and 3D-QSAR study.

PubMed

Wang, Li; Bao, Bo-Bo; Song, Guo-Qing; Chen, Cheng; Zhang, Xu-Meng; Lu, Wei; Wang, Zefang; Cai, Yan; Li, Shuang; Fu, Sheng; Song, Fu-Hang; Yang, Haitao; Wang, Jian-Guo

2017-09-08

The worldwide outbreak of severe acute respiratory syndrome (SARS) in 2003 had caused a high rate of mortality. Main protease (M pro ) of SARS-associated coronavirus (SARS-CoV) is an important target to discover pharmaceutical compounds for the therapy of this life-threatening disease. During the course of screening new anti-SARS agents, we have identified that a series of unsymmetrical aromatic disulfides inhibited SARS-CoV M pro significantly for the first time. Herein, 40 novel unsymmetrical aromatic disulfides were synthesized chemically and their biological activities were evaluated in vitro against SARS-CoV M pro . These novel compounds displayed excellent IC 50 data in the range of 0.516-5.954 μM. Preliminary studies indicated that these disulfides are reversible and mpetitive inhibitors. A possible binding mode was generated via molecular docking simulation and a comparative field analysis (CoMFA) model was constructed to understand the structure-activity relationships. The present research therefore has provided some meaningful guidance to design and identify anti-SARS drugs with totally new chemical structures. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Monocyclic aromatic amines as potential human carcinogens: old is new again

PubMed Central

Skipper, Paul L.; Kim, Min Young; Sun, H.-L. Patty; Wogan, Gerald N.; Tannenbaum, Steven R.

2010-01-01

Alkylanilines are a group of chemicals whose ubiquitous presence in the environment is a result of the multitude of sources from which they originate. Exposure assessments indicate that most individuals experience lifelong exposure to these compounds. Many alkylanilines have biological activity similar to that of the carcinogenic multi-ring aromatic amines. This review provides an overview of human exposure and biological effects. It also describes recent investigations into the biochemical mechanisms of action that lead to the assessment that they are most probably more complex than those of the more extensively investigated multi-ring aromatic amines. Not only is nitrenium ion chemistry implicated in DNA damage by alkylanilines but also reactions involving quinone imines and perhaps reactive oxygen species. Recent results described here indicate that alkylanilines can be potent genotoxins for cultured mammalian cells when activated by exogenous or endogenous phase I and phase II xenobiotic-metabolizing enzymes. The nature of specific DNA damage products responsible for mutagenicity remains to be identified but evidence to date supports mechanisms of activation through obligatory N-hydroxylation as well as subsequent conjugation by sulfation and/or acetylation. A fuller understanding of the mechanisms of alkylaniline genotoxicity is expected to provide important insights into the environmental and genetic origins of one or more human cancers and may reveal a substantial role for this group of compounds as potential human chemical carcinogens. PMID:19887514

Searching for new sources of innovative products for the food industry within halophyte aromatic plants: In vitro antioxidant activity and phenolic and mineral contents of infusions and decoctions of Crithmum maritimum L.

PubMed

Pereira, Catarina Guerreiro; Barreira, Luísa; da Rosa Neng, Nuno; Nogueira, José Manuel Florêncio; Marques, Cátia; Santos, Tamára F; Varela, João; Custódio, Luísa

2017-09-01

Aromatic halophyte plants are an outstanding source of bioactive compounds and natural products with potential use in the food industry. This work reports the in vitro antioxidant activity, toxicity, polyphenolic profile and mineral contents of infusions and decoctions from stems, leaves and flowers of Crithmum maritimum L., an aromatic and edible maritime halophyte (sea fennel). Aspalathus linearis (Burm.f.) Dahlg. (rooibos) herbal tea was used as a reference. Sea fennel's tisanes, particularly from leaves, were rich in phenolic compounds and five of them (p-hydroxybenzoic and ferulic acids, epicatechin, pyrocatechol and 4-hydroxybenzaldehyde) were here described in C. maritimum for the first time. Chlorogenic acid was the dominant phenolic determined. Na was the most abundant mineral in all tisanes followed by Ca and Mg in leaves' tisanes and K in flowers. Sea fennel's samples had a similar antioxidant activity than those from A. linearis, and had no significant toxicity towards four different mammalian cell lines. Altogether, our results suggest that sea fennel can be a source of products and/or molecules for the food industry with antioxidant properties and minerals in the form, for example, of innovative health-promoting herbal beverages. Copyright © 2017 Elsevier Ltd. All rights reserved.

Toward engineering E. coli with an autoregulatory system for lignin valorization.

PubMed

Wu, Weihua; Liu, Fang; Singh, Seema

2018-03-20

Efficient lignin valorization could add more than 10-fold the value gained from burning it for energy and is critical for economic viability of future biorefineries. However, lignin-derived aromatics from biomass pretreatment are known to be potent fermentation inhibitors in microbial production of fuels and other value-added chemicals. In addition, isopropyl-β-d-1-thiogalactopyranoside and other inducers are routinely added into fermentation broth to induce the expression of pathway enzymes, which further adds to the overall process cost. An autoregulatory system that can diminish the aromatics' toxicity as well as be substrate-inducible can be the key for successful integration of lignin valorization into future lignocellulosic biorefineries. Toward that goal, in this study an autoregulatory system is demonstrated that alleviates the toxicity issue and eliminates the cost of an external inducer. Specifically, this system is composed of a catechol biosynthesis pathway coexpressed with an active aromatic transporter CouP under induction by a vanillin self-inducible promoter, ADH7, to effectively convert the lignin-derived aromatics into value-added chemicals using Escherichia coli as a host. The constructed autoregulatory system can efficiently transport vanillin across the cell membrane and convert it to catechol. Compared with the system without CouP expression, the expression of catechol biosynthesis pathway with transporter CouP significantly improved the catechol yields about 30% and 40% under promoter pTrc and ADH7, respectively. This study demonstrated an aromatic-induced autoregulatory system that enabled conversion of lignin-derived aromatics into catechol without the addition of any costly, external inducers, providing a promising and economically viable route for lignin valorization. Copyright © 2018 the Author(s). Published by PNAS.

Metal complexes as DNA intercalators.

PubMed

Liu, Hong-Ke; Sadler, Peter J

2011-05-17

DNA has a strong affinity for many heterocyclic aromatic dyes, such as acridine and its derivatives. Lerman in 1961 first proposed intercalation as the source of this affinity, and this mode of DNA binding has since attracted considerable research scrutiny. Organic intercalators can inhibit nucleic acid synthesis in vivo, and they are now common anticancer drugs in clinical therapy. The covalent attachment of organic intercalators to transition metal coordination complexes, yielding metallointercalators, can lead to novel DNA interactions that influence biological activity. Metal complexes with σ-bonded aromatic side arms can act as dual-function complexes: they bind to DNA both by metal coordination and through intercalation of the attached aromatic ligand. These aromatic side arms introduce new modes of DNA binding, involving mutual interactions of functional groups held in close proximity. The biological activity of both cis- and trans-diamine Pt(II) complexes is dramatically enhanced by the addition of σ-bonded intercalators. We have explored a new class of organometallic "piano-stool" Ru(II) and Os(II) arene anticancer complexes of the type [(η(6)-arene)Ru/Os(XY)Cl](+). Here XY is, for example, ethylenediamine (en), and the arene ligand can take many forms, including tetrahydroanthracene, biphenyl, or p-cymene. Arene-nucleobase stacking interactions can have a significant influence on both the kinetics and thermodynamics of DNA binding. In particular, the cytotoxic activity, conformational distortions, recognition by DNA-binding proteins, and repair mechanisms are dependent on the arene. A major difficulty in developing anticancer drugs is cross-resistance, a phenomenon whereby a cell that is resistant to one drug is also resistant to another drug in the same class. These new complexes are non-cross-resistant with cisplatin towards cancer cells: they constitute a new class of anticancer agents, with a mechanism of action that differs from the anticancer drug cisplatin and its analogs. The Ru-arene complexes with dual functions are more potent towards cancer cells than their nonintercalating analogs. In this Account, we focus on recent studies of dual-function organometallic Ru(II)- and Os(II)-arene complexes and the methods used to detect arene-DNA intercalation. We relate these interactions to the mechanism of anticancer activity and to structure-activity relationships. The interactions between these complexes and DNA show close similarities to those of covalent polycyclic aromatic carcinogens, especially to N7-alkylating intercalation compounds. However, Ru-arene complexes exhibit some new features. Classical intercalation and base extrusion next to the metallated base is observed for {(η(6)-biphenyl)Ru(ethylenediamine)}(2+) adducts of a 14-mer duplex, while penetrating arene intercalation occurs for adducts of the nonaromatic bulky intercalator {(η(6)-tetrahydroanthracene)Ru(ethylenediamine)}(2+) with a 6-mer duplex. The introduction of dual-function Ru-arene complexes introduces new mechanisms of antitumor activity, novel mechanisms for attack on DNA, and new concepts for developing structure- activity relationships. We hope this discussion will stimulate thoughtful and focused research on the design of anticancer chemotherapeutic agents using these unique approaches.

Temperature-dependent regioselectivity of nucleophilic aromatic photosubstitution. Evidence that activation energy controls reactivity.

PubMed

Wubbels, Gene G; Tamura, Ryo; Gannon, Emmett J

2013-05-17

Irradiation (λ > 330 nm) of 2-chloro-4-nitroanisole (1) at 25 °C in aqueous NaOH forms three substitution photoproducts: 2-methoxy-5-nitrophenol (2), 2-chloro-4-nitrophenol (3), and 3-chloro-4-methoxyphenol (4), in chemical yields of 69.2%, 14.3%, and 16.5%. The activation energies for the elementary steps from the triplet state at 25 °C were determined to be 1.8, 2.4, and 2.7 kcal/mol, respectively. The chemical yields of each of the three products were determined for exhaustive irradiations at 0, 35, and 70 °C. The variation with temperature of the experimental yields is reproduced almost exactly by the yields calculated with the Arrhenius equation. This indicates that activation energy is the fundamental property related to regioselectivity in nucleophilic aromatic photosubstitution of the S(N)2 Ar* type. The many methods proposed for predicting regioselectivity in reactions of this type have had limited success and have not been related to activation energy.

Cancer Activation and Polymorphisms of Human Cytochrome P450 1B1

PubMed Central

Chun, Young-Jin; Kim, Donghak

2016-01-01

Human cytochrome P450 enzymes (P450s, CYPs) are major oxidative catalysts that metabolize various xenobiotic and endogenous compounds. Many carcinogens induce cancer only after metabolic activation and P450 enzymes play an important role in this phenomenon. P450 1B1 mediates bioactivation of many procarcinogenic chemicals and carcinogenic estrogen. It catalyzes the oxidation reaction of polycyclic aromatic carbons, heterocyclic and aromatic amines, and the 4-hydroxylation reaction of 17β-estradiol. Enhanced expression of P450 1B1 promotes cancer cell proliferation and metastasis. There are at least 25 polymorphic variants of P450 1B1 and some of these have been reported to be associated with eye diseases. In addition, P450 1B1 polymorphisms can greatly affect the metabolic activation of many procarcinogenic compounds. It is necessary to understand the relationship between metabolic activation of such substances and P450 1B1 polymorphisms in order to develop rational strategies for the prevention of its toxic effect on human health. PMID:27123158

Electrochemical regeneration of phenol-saturated activated carbon - proposal of a reactor.

PubMed

Zanella, Odivan; Bilibio, Denise; Priamo, Wagner Luiz; Tessaro, Isabel Cristina; Féris, Liliana Amaral

2017-03-01

An electrochemical process was used to investigate the activated carbon regeneration efficiency (RE) saturated with aromatics. For this purpose, an electrochemical reactor was developed and the operational conditions of this equipment were investigated, which is applied in activated carbon regeneration process. The influence of regeneration parameters such as processing time, the current used, the polarity and the processing fluid (electrolyte) were studied. The performance of electrochemical regeneration was evaluated by adsorption tests, using phenol as adsorbate. The increase in current applied and the process time was found to enhance the RE. Another aspect that indicated a better reactor performance was the type of electrolyte used, showing best results for NaCl. The polarity showed the highest influence on the process, when the cathodic regeneration was more efficient. The electrochemical regeneration process developed in this study presented regeneration capacities greater than 100% when the best process conditions were used, showing that this form of regeneration for activated carbon saturated with aromatics is very promising.

The Role of Human Aldo-Keto Reductases in the Metabolic Activation and Detoxication of Polycyclic Aromatic Hydrocarbons: Interconversion of PAH Catechols and PAH o-Quinones

PubMed Central

Zhang, Li; Jin, Yi; Huang, Meng; Penning, Trevor M.

2012-01-01

Polycyclic aromatic hydrocarbons (PAH) are ubiquitous environmental pollutants. They are procarcinogens requiring metabolic activation to elicit their deleterious effects. Aldo-keto reductases (AKR) catalyze the oxidation of proximate carcinogenic PAH trans-dihydrodiols to yield electrophilic and redox-active PAH o-quinones. AKRs are also found to be capable of reducing PAH o-quinones to form PAH catechols. The interconversion of o-quinones and catechols results in the redox-cycling of PAH o-quinones to give rise to the generation of reactive oxygen species and subsequent oxidative DNA damage. On the other hand, PAH catechols can be intercepted through phase II metabolism by which PAH o-quinones could be detoxified and eliminated. The aim of the present review is to summarize the role of human AKRs in the metabolic activation/detoxication of PAH and the relevance of phase II conjugation reactions to human lung carcinogenesis. PMID:23162467

Crystal structures of HIV-1 nonnucleoside reverse transcriptase inhibitors: N-benzyl-4-methyl-benzimidazoles

NASA Astrophysics Data System (ADS)

Ziółkowska, Natasza E.; Michejda, Christopher J.; Bujacz, Grzegorz D.

2009-07-01

HIV-1 nonnucleoside reverse transcriptase inhibitors are potentially specific and effective drugs in AIDS therapy. The presence of two aromatic systems with an angled orientation in the molecule of the inhibitor is crucial for interactions with HIV-1 RT. The inhibitor drives like a wedge into the cluster of aromatic residues of RT HIV-1 and restrains the enzyme in a conformation that blocks the chemical step of nucleotide incorporation. Structural studies provide useful information for designing new, more active inhibitors. The crystal structures of four NNRTIs are presented here. The investigated compounds are derivatives of N-benzyl-4-methyl-benzimidazole with various aliphatic and aromatic substituents at carbon 2 positions and a 2,6-dihalogeno-substituted N-benzyl moiety. Structural data reported here show that the conformation of the investigated compounds is relatively rigid. Such feature is important for the nonnucleoside inhibitor binding to HIV-1 reverse transcriptase.

Synthesis and Characterization of Poly (Arylene Ether Benzimidazole) Oligomers

NASA Technical Reports Server (NTRS)

Leonard, Michael J.

1995-01-01

Several poly(arylene ether benzimidazole) oligomers were prepared by the nucleophilic aromatic substitution reaction of a bisphenol benzimidazole and various alkyl-substituted aromatic bisphenols with an activated aromatic dihalide in N, N-dimethylacetarnide. Moderate to high molecular weight terpolymers were obtained in all cases, as shown by their inherent viscosities, which ranged from 0.50 to 0.87 dL g(sup -1). Glass transition temperatures (T(sub g)s) of polymer powders ranged from 267-280 C. Air-dried unoriented thin film T(sub g)s were markedly lower than those of the powders, whereas T(sub g)s of films dried in a nitrogen atmosphere were identical to those of the corresponding powders. In addition, air-dried films were dark amber and brittle, whereas nitrogen-dried films were yellow and creasable. Nitrogen-dried films showed slightly higher thin-film tensile properties than the air-dried films, as well.

Detecting the building blocks of aromatics

NASA Astrophysics Data System (ADS)

Joblin, Christine; Cernicharo, José

2018-01-01

Interstellar clouds are sites of active organic chemistry (1). Many small, gasphase molecules are found in the dark parts of the clouds that are protected from ultraviolet (UV) photons, but these molecules photodissociate in the external layers of the cloud that are exposed to stellar radiation (see the photo). These irradiated regions are populated by large polycyclic aromatic hydrocarbons (PAHs) with characteristic infrared (IR) emission features. These large aromatics are expected to form from benzene (C6H6), which is, however, difficult to detect because it does not have a permanent dipole moment and can only be detected via its IR absorption transitions against a strong background source (2). On page 202 of this issue, McGuire et al. (3) report the detection of benzonitrile (c-C6H5CN) with radio telescopes. Benzonitrile likely forms in the reaction of CN with benzene; from its observation, it is therefore possible to estimate the abundance of benzene itself.

Toxicity of used drilling fluids to mysids (Mysidopsis bahia)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gaetz, C.T.; Montgomery, R.; Duke, T.W.

1986-01-01

Static, acute toxicity tests were conducted with mysids (Mysidopsis bahia) and 11 used drilling fluids (also called drilling muds) obtained from active drilling platforms in the Gulf of Mexico, U.S.A. Each whole mud was tested, along with three phases of each mud: a liquid phase with all particulate materials removed; a suspended particulate phase composed of soluble and lighter particulate fractions; and a solid phase composed mainly of drill cuttings and rapidly settling particulates. These muds represented seven of the eight generic mud types described by the U.S. Environmental Protection Agency for use on the U.S. Outer Continental Shelf. Themore » toxicity of the 11 muds tested was apparently enhanced by the presence of aromatics. Furthermore, one mud tested repeatedly showed loss of toxicity with time, possibly from volatilization of aromatic fractions. The data demonstrated that aromatics in the drilling fluids affected their toxicity to M. bahia.« less

Effect of three aromatic hydrocarbons on respiration and heart rates of the mussel, mytilus californianus

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sabourin, T.D.; Tullis, R.E.

1981-06-01

The effects of petroleum derivatives on morality of marine invertebrates is now well established. Aromatics are considered to be the most toxic of all oil fractions. Recent studies of marine invertebrates have focused mainly upon respiration, locomotion, and growth. The filter feeding marine bivalves have received primary attention due to their proximity to coastal oil spills, importance in human food consumption and possible role in petroleum hydrocarbon bioconcentration. If these organisms are to be used as monitors in the future, then it is important to learn something of how quickly the bivalve responds metabolically to changes in ambient levels ofmore » petroleum hydrocarbons. Respiration and heart activity reveal a great deal of information concerning the physiological state of the bivalve. We report measrements of these two variables in the mussel, Mytilus californianus (Conrad), under conditions of exposure to, and recovery from, three aromatic hydrocarbons.« less

Copper Causes Regiospecific Formation of C4F8-Containing Six-Membered Rings and their Defluorination/Aromatization to C4F4-Containing Rings in Triphenylene/1,4-C4F8I2 Reactions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rippy, Kerry C.; Bukovsky, Eric V.; Clikeman, Tyler T.

The presence of Cu in reactions of triphenylene (TRPH) and 1,4-C4F8I2 at 360 °C led to regiospecific substitution of TRPH ortho C(β) atoms to form C4F8-containing rings, completely suppressing substitution on C(α) atoms. In addition, Cu caused selective reductive-defluorination/aromatization (RD/A) to form C4F4- containing aromatic rings. Without Cu, the reactions of TRPH and 1,4- C4F8I2 were not regiospecific and no RD/A was observed. These results, supported by DFT calculations, are the first examples of Cupromoted (i) regiospecific perfluoroannulation, (ii) preparative C–F activation, and (iii) RD/A. HPLC-purified products were characterized by X-ray diffraction, low-temperature PES, and 1H/19F NMR.

Natural mediators in the oxidation of polycyclic aromatic hydrocarbons by laccase mediator systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johannes, C.; Majcherczyk, A.

2000-02-01

The oxidation of polycyclic aromatic compounds was studied in systems consisting of laccase from Trametes versicolor and so-called mediator compounds. The enzymatic oxidation of acenaphthene, acenaphthylene, anthracene, and fluorene was mediated by various laccase substrates (phenols and aromatic amines) or compounds produced and secreted by white rot fungi. The best natural mediators, such as phenol, aniline, 4-hydroxybenzoic acid, and 4-hydroxybenzyl alcohol were as efficient as the previously described synthetic compounds ABTS [2,2{prime}-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid)] and 1-hydroxybenzotriazole. The oxidation efficiency increased proportionally with the redox potentials of the phenolic mediators up to a maximum value of 0.9 V and decreased thereafter withmore » redox potentials exceeding this value. Natural compounds such as methionine, cysteine, and reduced glutathione, containing sulfhydryl groups, were also active as mediator compounds.« less

Dehalogenation of aromatics by nucleophilic aromatic substitution.

PubMed

Sadowsky, Daniel; McNeill, Kristopher; Cramer, Christopher J

2014-09-16

Nucleophilic aromatic substitution has been implicated as a mechanism for both the biotic and abiotic hydrodehalogenation of aromatics. Two mechanisms for the aqueous dehalogenation of aromatics involving nucleophilic aromatic substitution with hydride as a nucleophile are investigated using a validated density functional and continuum solvation protocol. For chlorinated and brominated aromatics, nucleophilic addition ortho to carbon-halogen bonds via an anionic intermediate is predicted to be the preferred mechanism in the majority of cases, while concerted substitution is predicted to be preferred for most fluorinated aromatics. Nucleophilic aromatic substitution reactions with the hydroxide and hydrosulfide anions as nucleophiles are also investigated and compared.

The shikimate pathway: review of amino acid sequence, function and three-dimensional structures of the enzymes.

PubMed

Mir, Rafia; Jallu, Shais; Singh, T P

2015-06-01

The aromatic compounds such as aromatic amino acids, vitamin K and ubiquinone are important prerequisites for the metabolism of an organism. All organisms can synthesize these aromatic metabolites through shikimate pathway, except for mammals which are dependent on their diet for these compounds. The pathway converts phosphoenolpyruvate and erythrose 4-phosphate to chorismate through seven enzymatically catalyzed steps and chorismate serves as a precursor for the synthesis of variety of aromatic compounds. These enzymes have shown to play a vital role for the viability of microorganisms and thus are suggested to present attractive molecular targets for the design of novel antimicrobial drugs. This review focuses on the seven enzymes of the shikimate pathway, highlighting their primary sequences, functions and three-dimensional structures. The understanding of their active site amino acid maps, functions and three-dimensional structures will provide a framework on which the rational design of antimicrobial drugs would be based. Comparing the full length amino acid sequences and the X-ray crystal structures of these enzymes from bacteria, fungi and plant sources would contribute in designing a specific drug and/or in developing broad-spectrum compounds with efficacy against a variety of pathogens.

A hydroxycinnamoyltransferase responsible for synthesizing suberin aromatics in Arabidopsis

PubMed Central

Gou, Jin-Ying; Yu, Xiao-Hong; Liu, Chang-Jun

2009-01-01

Suberin, a polyester polymer in the cell wall of terrestrial plants, controls the transport of water and nutrients and protects plant from pathogenic infections and environmental stresses. Structurally, suberin consists of aliphatic and aromatic domains; p-hydroxycinnamates, such as ferulate, p-coumarate, and/or sinapate, are the major phenolic constituents of the latter. By analyzing the “wall-bound” phenolics of mutant lines of Arabidopsis deficient in a family of acyl-CoA dependent acyltransferase (BAHD) genes, we discovered that the formation of aromatic suberin in Arabidopsis, primarily in seed and root tissues, depends on a member of the BAHD superfamily of enzymes encoded by At5g41040. This enzyme exhibits an ω-hydroxyacid hydroxycinnamoyltransferase activity with an in vitro kinetic preference for feruloyl-CoA and 16-hydroxypalmitic acid. Knocking down or knocking out the At5g41040 gene in Arabidopsis reduces specifically the quantity of ferulate in suberin, but does not affect the accumulation of p-coumarate or sinapate. The loss of the suberin phenolic differentially affects the aliphatic monomer loads and alters the permeability and sensitivity of seeds and roots to salt stress. This highlights the importance of suberin aromatics in the polymer's function. PMID:19846769

Chemical fingerprinting applied to the evaluation of marine oil pollution in the coasts of Canary Islands (Spain).

PubMed

Peña-Méndez, E M; Astorga-España, M S; García-Montelongo, F J

2001-01-01

Chemical fingerprinting approach to environmental assessment is illustrated in the evaluation of marine oil pollution in the coasts using two limpet species as bioindicator organisms, and based on profiles and concentrations of n-alkanes and aromatic hydrocarbons in their tissues. Accidental and chronic releases of hydrocarbons can contaminate the marine environment of the Canary Islands not only because of their geographical situation but also because of the very dense tanker traffic around. This situation affects coastal areas, fishing activities, tourism resort, etc. Concentrations of n-alkanes and aromatic hydrocarbons (polycyclic aromatic hydrocarbons and methyl-polycyclic aromatic hydrocarbons) in the soft tissues of the marine intertidal and subtidal limpets, Patella crenata and Patella ullysiponensis aspera, were evaluated. Limpet samples were collected at monthly intervals, at three locations on the southeast coast of Tenerife over a 3-year period (1991-93). Levels of hydrocarbons found in limpets are similar to concentrations found in unpolluted areas around the world. From application of principal component analysis, the interpretation of variable loading plots gives information on variable correlation and can be used to distinguish among potential sources of pollution and the ability of studied molluscs to be used as bioindicator organisms.

Synthesis and biological evaluation of novel aromatic and heterocyclic bis-sulfonamide Schiff bases as carbonic anhydrase I, II, VII and IX inhibitors.

PubMed

Akocak, Suleyman; Lolak, Nabih; Nocentini, Alessio; Karakoc, Gulcin; Tufan, Anzel; Supuran, Claudiu T

2017-06-15

A series of sixteen novel aromatic and heterocyclic bis-sulfonamide Schiff bases were prepared by conjugation of well known aromatic and heterocyclic aminosulfonamide carbonic anhydrase (CA, EC 4.2.1.1) inhibitor pharmacophores with aromatic and heterocyclic bis-aldehydes. The obtained bis-sulfonamide Schiff bases were investigated as inhibitors of four selected human (h) CA isoforms, hCA I, hCA II, hCA VII and hCA IX. Most of the newly synthesized compounds showed a good inhibitory profile against isoforms hCA II and hCA IX, also showing moderate selectivity against hCA I and VII. Several efficient lead compounds were identified among this bis-sulfonamide Schiff bases with low nanomolar to sub-nanomolar activity against hCA II (K i s ranging between 0.4 and 861.1nM) and IX (K i s between 0.5 and 933.6nM). Since hCA II and hCA IX are important drug targets (antiglaucoma and anti-tumor agents), these isoform-selective inhibitors may be considered of interest for various biomedical applications. Copyright © 2017 Elsevier Ltd. All rights reserved.

Stabilization of the Nitric Oxide (NO) Prodrugs and Anti-Cancer Leads, PABA/NO and Double JS-K through Incorporation into PEG-Protected Nanoparticles

PubMed Central

Kumar, Varun; Hong, Sam Y.; Maciag, Anna E.; Saavedra, Joseph E.; Adamson, Douglas H.; Prud'homme, Robert K.; Keefer, Larry K.; Chakrapani, Harinath

2009-01-01

Here we report the stabilization of the nitric oxide (NO) prodrugs and anti-cancer lead compounds, PABA/NO (O2-{2,4-dinitro-5-[4-(N-methylamino)benzoyloxy]phenyl} 1-(N,N-dimethylamino)diazen-1-ium-1,2-diolate) and “Double JS-K” (1,5-bis{[1-[(4-ethoxycarbonyl)piperazin-1-yl]diazen-1-ium-1,2-diol-2-ato]-2,4-dinitrobenzene), through their incorporation into polymer-protected nanoparticles. The prodrugs were formulated in block copolymer-stabilized nanoparticles with sizes from 220 to 450 nm by a novel rapid precipitation process. The block copolymers, with polyethylene glycol (PEG) soluble blocks, provide a steric barrier against NO prodrug activation by glutathione. Too rapid activation and NO release has been a major barrier to effective administration of this class of compounds. The nanoparticle stabilized PABA/NO from attack by glutathione as evidenced by a significant increase in time taken for 50% decomposition from 15 min (unformulated) to 5 h (formulated); in the case of Double JS-K, the 50% decomposition time was extended from 4.5 min (unformulated) to 40 min (formulated). The more hydrophobic PABA/NO produced more stable nanoparticles and correspondingly more extended release times in comparison with Double JS-K. The hydrophobic blocks of the polymer were either polystyrene or polylactide. Both blocks produced nanoparticles of approximately the same size and release kinetics. This combination of PEG-protected nanoparticles with sizes appropriate for cancer targeting by enhanced permeation and retention (EPR) and delayed release of NO may afford enhanced therapeutic benefit. PMID:20000791

Stabilization of the nitric oxide (NO) prodrugs and anticancer leads, PABA/NO and Double JS-K, through incorporation into PEG-protected nanoparticles.

PubMed

Kumar, Varun; Hong, Sam Y; Maciag, Anna E; Saavedra, Joseph E; Adamson, Douglas H; Prud'homme, Robert K; Keefer, Larry K; Chakrapani, Harinath

2010-02-01

We report the stabilization of the nitric oxide (NO) prodrugs and anticancer lead compounds, PABA/NO (O(2)-{2,4-dinitro-5-[4-(N-methylamino)benzoyloxy]phenyl} 1-(N,N-dimethylamino)diazen-1-ium-1,2-diolate) and "Double JS-K" 1,5-bis-{1-[(4-ethoxycarbonyl)piperazin-1-yl]diazen-1-ium-1,2-diol-2-ato}-2,4-dinitrobenzene, through their incorporation into polymer-protected nanoparticles. The prodrugs were formulated in block copolymer-stabilized nanoparticles with sizes from 220 to 450 nm by a novel rapid precipitation process. The block copolymers, with polyethylene glycol (PEG) soluble blocks, provide a steric barrier against NO prodrug activation by glutathione. Too rapid activation and NO release has been a major barrier to effective administration of this class of compounds. The nanoparticle stabilized PABA/NO are protected from attack by glutathione as evidenced by a significant increase in time taken for 50% decomposition from 15 min (unformulated) to 5 h (formulated); in the case of Double JS-K, the 50% decomposition time was extended from 4.5 min (unformulated) to 40 min (formulated). The more hydrophobic PABA/NO produced more stable nanoparticles and correspondingly more extended release times in comparison with Double JS-K. The hydrophobic blocks of the polymer were either polystyrene or polylactide. Both blocks produced nanoparticles of approximately the same size and release kinetics. This combination of PEG-protected nanoparticles with sizes appropriate for cancer targeting by enhanced permeation and retention (EPR) and delayed release of NO may afford enhanced therapeutic benefit.

Structure-Activity Relationships for the Antifungal Activity of Selective Estrogen Receptor Antagonists Related to Tamoxifen

PubMed Central

Butts, Arielle; Martin, Jennifer A.; DiDone, Louis; Bradley, Erin K.; Mutz, Mitchell; Krysan, Damian J.

2015-01-01

Cryptococcosis is one of the most important invasive fungal infections and is a significant contributor to the mortality associated with HIV/AIDS. As part of our program to repurpose molecules related to the selective estrogen receptor modulator (SERM) tamoxifen as anti-cryptococcal agents, we have explored the structure-activity relationships of a set of structurally diverse SERMs and tamoxifen derivatives. Our data provide the first insights into the structural requirements for the antifungal activity of this scaffold. Three key molecular characteristics affecting anti-cryptococcal activity emerged from our studies: 1) the presence of an alkylamino group tethered to one of the aromatic rings of the triphenylethylene core; 2) an appropriately sized aliphatic substituent at the 2 position of the ethylene moiety; and 3) electronegative substituents on the aromatic rings modestly improved activity. Using a cell-based assay of calmodulin antagonism, we found that the anti-cryptococcal activity of the scaffold correlates with calmodulin inhibition. Finally, we developed a homology model of C. neoformans calmodulin and used it to rationalize the structural basis for the activity of these molecules. Taken together, these data and models provide a basis for the further optimization of this promising anti-cryptococcal scaffold. PMID:26016941

Structure of Cryptosporidium IMP dehydrogenase bound to an inhibitor with in vivo antiparasitic activity

DOE PAGES

Kim, Youngchang; Makowska-Grzyska, Magdalena; Gorla, Suresh Kumar; ...

2015-04-21

Inosine 5´-monophosphate dehydrogenase (IMPDH) is a promising target for the treatment of Cryptosporidium infections. Here, the structure of C. parvum IMPDH ( CpIMPDH) in complex with inosine 5´-monophosphate (IMP) and P131, an inhibitor with in vivo anticryptosporidial activity, is reported. P131 contains two aromatic groups, one of which interacts with the hypoxanthine ring of IMP, while the second interacts with the aromatic ring of a tyrosine in the adjacent subunit. In addition, the amine and NO 2 moieties bind in hydrated cavities, forming water-mediated hydrogen bonds to the protein. The design of compounds to replace these water molecules is amore » new strategy for the further optimization of C. parvum inhibitors for both antiparasitic and antibacterial applications.« less

Structure of Cryptosporidium IMP dehydrogenase bound to an inhibitor with in vivo antiparasitic activity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Youngchang; Makowska-Grzyska, Magdalena; Gorla, Suresh Kumar

2015-04-21

Inosine 5'-monophosphate dehydrogenase (IMPDH) is a promising target for the treatment ofCryptosporidiuminfections. Here, the structure ofC. parvumIMPDH (CpIMPDH) in complex with inosine 5'-monophosphate (IMP) and P131, an inhibitor within vivoanticryptosporidial activity, is reported. P131 contains two aromatic groups, one of which interacts with the hypoxanthine ring of IMP, while the second interacts with the aromatic ring of a tyrosine in the adjacent subunit. In addition, the amine and NO 2moieties bind in hydrated cavities, forming water-mediated hydrogen bonds to the protein. The design of compounds to replace these water molecules is a new strategy for the further optimization ofC. parvuminhibitorsmore » for both antiparasitic and antibacterial applications.« less

Multifaceted regulations of gateway enzyme phenylalanine ammonia-lyase in the biosynthesis of phenylpropanoids

DOE PAGES

Zhang, Xuebin; Liu, Chang-Jun

2014-12-11

Phenylpropanoid biosynthesis in plants engenders a vast variety of aromatic metabolites critically important for their growth, development, and environmental adaptation. Some of these aromatic compounds have high economic value. Phenylalanine ammonia-lyase (PAL) is the first committed enzyme in the pathway; it diverts the central flux of carbon from primary metabolism to the synthesis of myriad phenolics. Over the decades, many studies have shown that exquisite regulatory mechanisms at multiple levels control the transcription and the enzymatic activity of PALs. In this review, we present a current overview on our understanding of the complicated regulatory mechanisms governing PAL's activity; we particularlymore » highlight recent progresses in unraveling its post-translational modifications, its metabolite feedback regulation, and its enzyme organization.« less

Intermolecular hydrogen bonds in hetero-complexes of biologically active aromatic molecules probed by the methods of vibrational spectroscopy

NASA Astrophysics Data System (ADS)

Semenov, M. A.; Blyzniuk, Iu. N.; Bolbukh, T. V.; Shestopalova, A. V.; Evstigneev, M. P.; Maleev, V. Ya.

2012-09-01

By the methods of vibrational spectroscopy (Infrared and Raman) the investigation of the hetero-association of biologically active aromatic compounds: flavin-mononucleotide (FMN), ethidium bromide (EB) and proflavine (PRF) was performed in aqueous solutions. It was shown that between the functional groups (Cdbnd O and NH2) the intermolecular hydrogen bonds are formed in the hetero-complexes FMN-EB and FMN-PRF, additionally stabilizing these structures. An estimation of the enthalpy of Н-bonding obtained from experimental shifts of carbonyl vibrational frequencies has shown that the H-bonds do not dominate in the magnitude of experimentally measured total enthalpy of the hetero-association reactions. The main stabilization is likely due to intermolecular interactions of the molecules in these complexes and their interaction with water environment.

[Studies by means of 1H NMR spectroscopy of complex formation of aromatic biologically active compounds with antibiotic topotecan].

PubMed

Mosunov, A A; Kostiukov, V V; Evstigneev, M P

2012-01-01

The analysis of heteroassociation of antibiotic topotecan (TPT) with aromatic biologically active compounds (BAC): caffeine, mutagens ethidium bromide and proflavine, antibiotic daunomycin, vitamins flavin-mononucleotide and nicotinamide, has been carried out in the work using 1H NMR spectroscopy data. The equilibrium constants of heteroassociation and induced chemical shifts of the protons have been obtained in the complexes with BAC. It is found that the complex formation TPT-BAC has the nature of stacking of the chromophores, additionally stabilized in the case of proflavine by intermolecular hydrogen bond. Calculation of the basic components of the Gibbs free energy of the complexation reactions is carried out, and the factors which stabilize and destabilize the heterocomplexes of molecules are revealed.

Multifaceted regulations of gateway enzyme phenylalanine ammonia-lyase in the biosynthesis of phenylpropanoids

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Xuebin; Liu, Chang-Jun

Phenylpropanoid biosynthesis in plants engenders a vast variety of aromatic metabolites critically important for their growth, development, and environmental adaptation. Some of these aromatic compounds have high economic value. Phenylalanine ammonia-lyase (PAL) is the first committed enzyme in the pathway; it diverts the central flux of carbon from primary metabolism to the synthesis of myriad phenolics. Over the decades, many studies have shown that exquisite regulatory mechanisms at multiple levels control the transcription and the enzymatic activity of PALs. In this review, we present a current overview on our understanding of the complicated regulatory mechanisms governing PAL's activity; we particularlymore » highlight recent progresses in unraveling its post-translational modifications, its metabolite feedback regulation, and its enzyme organization.« less

Quantitative structure-activity relationships studies of CCR5 inhibitors and toxicity of aromatic compounds using gene expression programming.

PubMed

Shi, Weimin; Zhang, Xiaoya; Shen, Qi

2010-01-01

Quantitative structure-activity relationship (QSAR) study of chemokine receptor 5 (CCR5) binding affinity of substituted 1-(3,3-diphenylpropyl)-piperidinyl amides and ureas and toxicity of aromatic compounds have been performed. The gene expression programming (GEP) was used to select variables and produce nonlinear QSAR models simultaneously using the selected variables. In our GEP implementation, a simple and convenient method was proposed to infer the K-expression from the number of arguments of the function in a gene, without building the expression tree. The results were compared to those obtained by artificial neural network (ANN) and support vector machine (SVM). It has been demonstrated that the GEP is a useful tool for QSAR modeling. Copyright 2009 Elsevier Masson SAS. All rights reserved.

Spectroscopic Diagnosis of Excited-State Aromaticity: Capturing Electronic Structures and Conformations upon Aromaticity Reversal.

PubMed

Oh, Juwon; Sung, Young Mo; Hong, Yongseok; Kim, Dongho

2018-03-06

Aromaticity, the special energetic stability derived from cyclic [4 n + 2]π-conjugated electronic structures, has been the topic of intense interest in chemistry because it plays a critical role in rationalizing molecular stability, reactivity, and physical/chemical properties. Recently, the pioneering work by Colin Baird on aromaticity reversal, postulating that aromatic (antiaromatic) character in the ground state reverses to antiaromatic (aromatic) character in the lowest excited triplet state, has attracted much scientific attention. The completely reversed aromaticity in the excited state provides direct insight into understanding the photophysical/chemical properties of photoactive materials. In turn, the application of aromatic molecules to photoactive materials has led to numerous studies revealing this aromaticity reversal. However, most studies of excited-state aromaticity have been based on the theoretical point of view. The experimental evaluation of aromaticity in the excited state is still challenging and strenuous because the assessment of (anti)aromaticity with conventional magnetic, energetic, and geometric indices is difficult in the excited state, which practically restricts the extension and application of the concept of excited-state aromaticity. Time-resolved optical spectroscopies can provide a new and alternative avenue to evaluate excited-state aromaticity experimentally while observing changes in the molecular features in the excited states. Time-resolved optical spectroscopies take advantage of ultrafast laser pulses to achieve high time resolution, making them suitable for monitoring ultrafast changes in the excited states of molecular systems. This can provide valuable information for understanding the aromaticity reversal. This Account presents recent breakthroughs in the experimental assessment of excited-state aromaticity and the verification of aromaticity reversal with time-resolved optical spectroscopic measurements. To scrutinize this intriguing and challenging scientific issue, expanded porphyrins have been utilized as the ideal testing platform for investigating aromaticity because they show distinct aromatic and antiaromatic characters with aromaticity-specific spectroscopic features. Expanded porphyrins exhibit perfect aromatic and antiaromatic congener pairs having the same molecular framework but different numbers of π electrons, which facilitates the study of the pure effect of aromaticity by comparative analyses. On the basis of the characteristics of expanded porphyrins, time-resolved electronic and vibrational absorption spectroscopies capture the changes in electronic structure and molecular conformations driven by the change in aromaticity and provide clear evidence for aromaticity reversal in the excited states. The approaches described in this Account pave the way for the development of new and alternative experimental indices for the evaluation of excited-state aromaticity, which will enable overarching and fundamental comprehension of the role of (anti)aromaticity in the stability, dynamics, and reactivity in the excited states with possible implications for practical applications.

Inhibition of hippocampal aromatization impairs spatial memory performance in a male songbird.

PubMed

Bailey, David J; Ma, Chunqi; Soma, Kiran K; Saldanha, Colin J

2013-12-01

Recent studies have revealed the presence and regulation of aromatase at the vertebrate synapse, and identified a critical role played by presynaptic estradiol synthesis in the electrophysiological response to auditory and other social cues. However, if and how synaptic aromatization affects behavior remains to be directly tested. We have exploited 3 characteristics of the zebra finch hippocampus (HP) to test the role of synaptocrine estradiol provision on spatial memory function. Although the zebra finch HP contains abundant aromatase transcripts and enzyme activity, immunocytochemical studies reveal widespread pre- and postsynaptic, but sparse to undetectable somal, localization of this enzyme. Further, the superficial location of the avian HP makes possible the more exclusive manipulation of its neurochemical characteristics without perturbation of the neuropil and the resultant induction of astroglial aromatase. Last, as in other vertebrates, the HP is critical for spatial memory performance in this species. Here we report that local inhibition of hippocampal aromatization impairs spatial memory performance in an ecologically valid food-finding task. Local aromatase inhibition also resulted in lower levels of estradiol in the HP, but not in adjacent brain areas, and was achieved without the induction of astroglial aromatase. The observed decrement in acquisition and subsequent memory performance as a consequence of lowered aromatization was similar to that achieved by lesioning this locus. Thus, hippocampal aromatization, much of which is achieved at the synapse in this species, is critical for spatial memory performance.

Lignans and aromatic glycosides from Piper wallichii and their antithrombotic activities.

PubMed

Shi, Yan-Ni; Shi, Yi-Ming; Yang, Lian; Li, Xing-Cong; Zhao, Jin-Hua; Qu, Yan; Zhu, Hong-Tao; Wang, Dong; Cheng, Rong-Rong; Yang, Chong-Ren; Xu, Min; Zhang, Ying-Jun

2015-03-13

Piper wallichii (Miq.) Hand.-Mazz. is a medicinal plant used widely for the treatment of rheumatoid arthritis, inflammatory diseases, cerebral infarction and angina in China. Previous study showed that lignans and neolignans from Piper spp. had potential inhibitory activities on platelet aggregation. In the present study, we investigated the chemical constituents of Piper wallichii and their antithrombotic activities, to support its traditional uses. The methanolic extract of the air-dried stems of Piper wallichii was separated and purified using various chromatographic methods, including semi-preparative HPLC. The chemical structures of the isolates were determined by detailed spectroscopic analysis, and acidic hydrolysis in case of the new glycoside 2. Determination of absolute configurations of the new compound 1 was facilitated by calculated electronic circular dichroism using time-dependent density-functional theory. All compounds were tested for their inhibitory effects on platelet aggregation induced by platelet activating factor (PAF) in rabbits׳ blood model, from which the active ones were further evaluated the in vivo antithrombotic activity in zebrafish model. A new neolignan, piperwalliol A (1), and four new aromatic glycosides, piperwalliosides A-D (2-5) were isolated from the stems of Piper wallichii, along with 25 known compounds, including 13 lignans, six aromatic glycosides, two phenylpropyl aldehydes, and four biphenyls. Five known compounds (6-10) showed in vitro antiplatelet aggregation activities. Among them, (-)-syringaresinol (6) was the most active compound with an IC50 value of 0.52 mM. It is noted that in zebrafish model, the known lignan 6 showed good in vivo antithrombotic effect with a value of 37% at a concentration of 30 μM, compared with the positive control aspirin with the inhibitory value of 74% at a concentration of 125μM. This study demonstrated that lignans, phenylpropanoid and biphenyl found in Piper wallichii may be responsible for antithrombotic effect of the titled plant. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Biotransformation and induction: implications for toxicity, bioaccumulation and monitoring of environmental xenobiotics in fish.

PubMed Central

Kleinow, K M; Melancon, M J; Lech, J J

1987-01-01

Biotransformation of xenobiotics in fish occurs by many of the same reactions as in mammals. These reactions have been shown to affect the bioaccumulation, persistence, residue dynamics, and toxicity of select chemicals in fish. P-450-dependent monooxygenase activity of fish can be induced by polycyclic aromatic hydrocarbons, but phenobarbital-type agents induce poorly, if at all. Fish monooxygenase activity exhibits ideal temperature compensation and sex-related variation. Induction of monooxygenase activity by polycyclic aromatic hydrocarbons can result in qualitative as well as quantitative changes in the metabolic profile of a chemical. Induction can also alter toxicity. In addition, multiple P-450 isozymes have been described for several fish species. The biotransformation products of certain chemicals have been related to specific P-450 isozymes, and the formation of these products can be influenced by induction. Exposure of fish to low levels of certain environmental contaminants has resulted in induction of specific monooxygenase activities and monitoring of such activities has been suggested as a means of identifying areas of pollutant exposure in the wild. PMID:3297653

Adsorption of guanidinium collectors on aluminosilicate minerals - a density functional study.

PubMed

Nulakani, Naga Venkateswara Rao; Baskar, Prathab; Patra, Abhay Shankar; Subramanian, Venkatesan

2015-10-07

In this density functional theory based investigation, we have modelled and studied the adsorption behaviour of guanidinium cations and substituted (phenyl, methoxy phenyl, nitro phenyl and di-nitro phenyl) guanidinium cationic collectors on the basal surfaces of kaolinite and goethite. The adsorption behaviour is assessed in three different media, such as gas, explicit water and pH medium, to understand the affinity of GC collectors to the SiO4 tetrahedral and AlO6 octahedral surfaces of kaolinite. The tetrahedral siloxane surface possesses a larger binding affinity to GC collectors than the octahedral sites due to the presence of surface exposed oxygen atoms that are active in the intermolecular interactions. Furthermore, the inductive electronic effects of substituted guanidinium cations also play a key role in the adsorption mechanism. Highly positive cations result in a stronger electrostatic interaction and preferential adsorption with the kaolinite surfaces than low positive cations. Computed interaction energies and electron densities at the bond critical points suggest that the adsorption of guanidinium cations on the surfaces of kaolinite and goethite is due to the formation of intra/inter hydrogen bonding networks. Also, the electrostatic interaction favours the high adsorption ability of GC collectors in the pH medium than gas phase and water medium. The structures and energies of GC collectors pave an intuitive view for future experimental studies on mineral flotation.

The Synthesis of Phenyl Acetylene Phenols for Development of New Explosives

NASA Astrophysics Data System (ADS)

Chikhradze, Nikoloz; Nadirashvili, Merab; Khomeriki, Sergo; Varshanidze, Iasha

2017-12-01

The purpose of this research is to produce derivatives of simple phenols as “raw material” for the synthesis of new phenolic explosives. A big number of valuable products is synthesized from phenol and its homologues including well-known explosives - picric acid, methyl picrate, cresolite, etc. In general, a structural modification of well-known explosives’ molecules is the most important among the methods for the synthesis of new explosives. This method can be used in certain modifications. For example, the synthesis of methyl picrate is possible not only to replace picric acid’s hydroxyl with metoxyl, but with nitration of anisole as well, i. e, by the reciprocating synthesis. Thus, to produce the new analogues of well-known phenolic explosives, the preliminary modification of simple phenols’ molecules and further nitration, presumably by a formation of dinitro derivatives may be performed. The alkylation of phenol, anisole and m - cresol by the secondary phenyl acetylene alcohols in the presence of concentrated phosphoric acid was carried out. Para-substituted alkynyl phenols with high yields were developed. The chemical transformations were carried out by a participation of their molecules’ active centres. The corresponding ethers, esters and saturated isologues have been synthesized. The article describes the conditions of a synthesis of 14 new phenyl acetylenes’ substances that may be used as substrates in a nitration reaction.

Antimicrobial Activity of Essential Oils Against Staphylococcus aureus in Fresh Sheep Cheese.

PubMed

Amatiste, Simonetta; Sagrafoli, Daniele; Giacinti, Giuseppina; Rosa, Giulia; Carfora, Virginia; Marri, Nicla; Tammaro, Andreana; Bovi, Emanuela; Rosati, Remo

2014-08-28

Essential oils (EOs) are aromatic oily liquids extracted from different parts of specific plants, well known especially for their aromatic and antibacterial properties. Nowadays, EOs are exploited in the food sector mainly for their aromatic properties. Thanks to their antimicrobial activity, however, they could also be used as additives to increase the safety and the shelf-life of food products. Aim of this study was to assess the antimicrobial activity of Thymus vulgaris L. oil and of Origanum vulgare L. oil against Staphylococcus aureus both in vitro and on fresh cheese, and to determine whether the use of EOs can modify the microbiological and/or chemical-physical properties of the products. The antimicrobial activity against S. aureus in vitro was assessed by preparation of the aromatogram (diffusion in agar test), minimum inhibitory concentration test and minimum bactericidal concentration assessment. Raw sheep milk was experimentally contaminated with a strain of S. aureus ATCC 25922 and was used to produce three types of fresh cheese: without EOs, with thyme and oregano EOs (both EOs at a concentration of 1:1000). The samples were analysed on the day of production, after three and seven days. The results obtained from the tests showed that the concentration of S. aureus and the counts of lactic flora remained unchanged for all types of cheese. Even the chemical-physical parameters were constant. The results of inhibition tests on the cheese disagree with those relating to the in vitro tests. Most likely this is due to the ability of EOs to disperse in the lipids the food: the higher the fat content is, the lower the oil fraction will be able to exert the antimicrobial activity.

Probing Mercaptobenzamides as HIV Inactivators via Nucleocapsid Protein 7.

PubMed

Saha, Mrinmoy; Scerba, Michael T; Shank, Nathaniel I; Hartman, Tracy L; Buchholz, Caitlin A; Buckheit, Robert W; Durell, Stewart R; Appella, Daniel H

2017-05-22

Human immunodeficiency virus type 1 (HIV-1) nucleocapsid protein 7 (NCp7), a zinc finger protein, plays critical roles in viral replication and maturation and is an attractive target for drug development. However, the development of drug-like molecules that inhibit NCp7 has been a significant challenge. In this study, a series of novel 2-mercaptobenzamide prodrugs were investigated for anti-HIV activity in the context of NCp7 inactivation. The molecules were synthesized from the corresponding thiosalicylic acids, and they are all crystalline solids and stable at room temperature. Derivatives with a range of amide side chains and aromatic substituents were synthesized and screened for anti-HIV activity. Wide ranges of antiviral activity were observed, with IC 50 values ranging from 1 to 100 μm depending on subtle changes to the substituents on the aromatic ring and side chain. Results from these structure-activity relationships were fit to a probable mode of intracellular activation and interaction with NCp7 to explain variations in antiviral activity. Our strategy to make a series of mercaptobenzamide prodrugs represents a general new direction to make libraries that can be screened for anti-HIV activity. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Structure-Function Relationships in Human Testis-determining Factor SRY

PubMed Central

Racca, Joseph D.; Chen, Yen-Shan; Maloy, James D.; Wickramasinghe, Nalinda; Phillips, Nelson B.; Weiss, Michael A.

2014-01-01

Human testis determination is initiated by SRY, a Y-encoded architectural transcription factor. Mutations in SRY cause 46 XY gonadal dysgenesis with female somatic phenotype (Swyer syndrome) and confer a high risk of malignancy (gonadoblastoma). Such mutations cluster in the SRY high mobility group (HMG) box, a conserved motif of specific DNA binding and bending. To explore structure-function relationships, we constructed all possible substitutions at a site of clinical mutation (W70L). Our studies thus focused on a core aromatic residue (position 15 of the consensus HMG box) that is invariant among SRY-related HMG box transcription factors (the SOX family) and conserved as aromatic (Phe or Tyr) among other sequence-specific boxes. In a yeast one-hybrid system sensitive to specific SRY-DNA binding, the variant domains exhibited reduced (Phe and Tyr) or absent activity (the remaining 17 substitutions). Representative nonpolar variants with partial or absent activity (Tyr, Phe, Leu, and Ala in order of decreasing side-chain volume) were chosen for study in vitro and in mammalian cell culture. The clinical mutation (Leu) was found to markedly impair multiple biochemical and cellular activities as respectively probed through the following: (i) in vitro assays of specific DNA binding and protein stability, and (ii) cell culture-based assays of proteosomal degradation, nuclear import, enhancer DNA occupancy, and SRY-dependent transcriptional activation. Surprisingly, however, DNA bending is robust to this or the related Ala substitution that profoundly impairs box stability. Together, our findings demonstrate that the folding, trafficking, and gene-regulatory function of SRY requires an invariant aromatic “buttress” beneath its specific DNA-bending surface. PMID:25258310

Designed beta-boomerang antiendotoxic and antimicrobial peptides: structures and activities in lipopolysaccharide.

PubMed

Bhunia, Anirban; Mohanram, Harini; Domadia, Prerna N; Torres, Jaume; Bhattacharjya, Surajit

2009-08-14

Lipopolysaccharide (LPS), an integral part of the outer membrane of Gram-negative bacteria, is involved in a variety of biological processes including inflammation, septic shock, and resistance to host-defense molecules. LPS also provides an environment for folding of outer membrane proteins. In this work, we describe the structure-activity correlation of a series of 12-residue peptides in LPS. NMR structures of the peptides derived in complex with LPS reveal boomerang-like beta-strand conformations that are stabilized by intimate packing between the two aromatic residues located at the 4 and 9 positions. This structural feature renders these peptides with a high ability to neutralize endotoxicity, >80% at 10 nM concentration, of LPS. Replacements of these aromatic residues either with Ala or with Leu destabilizes the boomerang structure with the concomitant loss of antiendotoxic and antimicrobial activities. Furthermore, the aromatic packing stabilizing the beta-boomerang structure in LPS is found to be maintained even in a truncated octapeptide, defining a structured LPS binding motif. The mode of action of the active designed peptides correlates well with their ability to perturb LPS micelle structures. Fourier transform infrared spectroscopy studies of the peptides delineate beta-type conformations and immobilization of phosphate head groups of LPS. Trp fluorescence studies demonstrated selective interactions with LPS and the depth of insertion into the LPS bilayer. Our results demonstrate the requirement of LPS-specific structures of peptides for endotoxin neutralizations. In addition, we propose that structures of these peptides may be employed to design proteins for the outer membrane.

FATE OF WATER SOLUBLE AZO DYES IN THE ACTIVATED SLUDGE PROCESS

EPA Science Inventory

The objective of this study was to determine the partitioning of water soluble azo dyes in the activated sludge process (ASP). Azo dyes are of concern because some of the dyes, dye precursors , and/or their degradation products such as aromatic amines (which are also dye precurso...

ESTIMATION OF MICROBIAL REDUCTIVE TRANSFORMATION RATES FOR CHLORINATED BENZENES AND PHENOLS USING A QUANTITATIVE STRUCTURE-ACTIVITY RELATIONSHIP APPROACH

EPA Science Inventory

A set of literature data was used to derive several quantitative structure-activity relationships (QSARs) to predict the rate constants for the microbial reductive dehalogenation of chlorinated aromatics. Dechlorination rate constants for 25 chloroaromatics were corrected for th...

Long-term control of root growth

DOEpatents

Burton, Frederick G.; Cataldo, Dominic A.; Cline, John F.; Skiens, W. Eugene

1992-05-26

A method and system for long-term control of root growth without killing the plants bearing those roots involves incorporating a 2,6-dinitroaniline in a polymer and disposing the polymer in an area in which root control is desired. This results in controlled release of the substituted aniline herbicide over a period of many years. Herbicides of this class have the property of preventing root elongation without translocating into other parts of the plant. The herbicide may be encapsulated in the polymer or mixed with it. The polymer-herbicide mixture may be formed into pellets, sheets, pipe gaskets, pipes for carrying water, or various other forms. The invention may be applied to other protection of buried hazardous wastes, protection of underground pipes, prevention of root intrusion beneath slabs, the dwarfing of trees or shrubs and other applications. The preferred herbicide is 4-difluoromethyl-N,N-dipropyl-2,6-dinitro-aniline, commonly known as trifluralin.

Method for disposing of hazardous wastes

DOEpatents

Burton, Frederick G.; Cataldo, Dominic A.; Cline, John F.; Skiens, W. Eugene

1995-01-01

A method and system for long-term control of root growth without killing the plants bearing those roots involves incorporating a 2,6-dinitroaniline in a polymer and disposing the polymer in an area in which root control is desired. This results in controlled release of the substituted aniline herbicide over a period of many years. Herbicides of this class have the property of preventing root elongation without translocating into other parts of the plant. The herbicide may be encapsulated in the polymer or mixed with it. The polymer-herbicide mixture may be formed into pellets, sheets, pipe gaskets, pipes for carrying water, or various other forms. The invention may be applied to other protection of buried hazardous wastes, protection of underground pipes, prevention of root intrusion beneath slabs, the dwarfing of trees or shrubs and other applications. The preferred herbicide is 4-difluoromethyl-N,N-dipropyl- 2,6-dinitro-aniline, commonly known as trifluralin.

Fluorescent aromatic sensors and their methods of use

NASA Technical Reports Server (NTRS)

Meador, Michael A. (Inventor); Tyson, Daniel S. (Inventor); Ilan, Ulvi F. (Inventor)

2012-01-01

Aromatic molecules that can be used as sensors are described. The aromatic sensors include a polycyclic aromatic hydrocarbon core with a five-membered imide rings fused to the core and at least two pendant aryl groups. The aromatic sensor molecules can detect target analytes or molecular strain as a result of changes in their fluorescence, in many cases with on-off behavior. Aromatic molecules that fluoresce at various frequencies can be prepared by altering the structure of the aromatic core or the substituents attached to it. The aromatic molecules can be used as sensors for various applications such as, for example, the detection of dangerous chemicals, biomedical diagnosis, and the detection of damage or strain in composite materials. Methods of preparing aromatic sensor molecules are also described.

Bacillus licheniformis affects the microbial community and metabolic profile in the spontaneous fermentation of Daqu starter for Chinese liquor making.

PubMed

Wang, Peng; Wu, Qun; Jiang, Xuejian; Wang, Zhiqiang; Tang, Jingli; Xu, Yan

2017-06-05

Chinese liquor is produced from spontaneous fermentation starter (Daqu) that provides the microbes, enzymes and flavors for liquor fermentation. To improve the flavor character of Daqu, we inoculated Bacillus licheniformis and studied the effect of this strain on the community structure and metabolic profile in Daqu fermentation. The microbial relative abundance changed after the inoculation, including the increase in Bacillus, Clavispora and Aspergillus, and the decrease in Pichia, Saccharomycopsis and some other genera. This variation was also confirmed by pure culture and coculture experiments. Seventy-three metabolites were identified during Daqu fermentation process. After inoculation, the average content of aromatic compounds were significantly enriched from 0.37mg/kg to 0.90mg/kg, and the average content of pyrazines significantly increased from 0.35mg/kg to 5.71mg/kg. The increase in pyrazines was positively associated with the metabolism of the inoculated Bacillus and the native genus Clavispora, because they produced much more pyrazines in their cocultures. Whereas the increase in aromatic compounds might be related to the change of in situ metabolic activity of several native genera, in particular, Aspergillus produced more aromatic compounds in cocultures with B. licheniformis. It indicated that the inoculation of B. licheniformis altered the flavor character of Daqu by both its own metabolic activity and the variation of in situ metabolic activity. Moreover, B. licheniformis inoculation influenced the enzyme activity of Daqu, including the significant increase in amylase activity (from 1.3gstarch/g/h to 1.7gstarch/g/h), and the significant decrease in glucoamylase activity (from 627.6mgglucose/g/h to 445.6mgglucose/g/h) and esterase activity (from 28.1mgethylcaproate/g/100h to 17.2mgethylcaproate/g/100h). These effects of inoculation were important factors for regulating the metabolism of microbial communities, hence for improving the flavor profile Daqu. Copyright © 2017 Elsevier B.V. All rights reserved.

Chemical and nanometer-scale structure of kerogen and its change during thermal maturation investigated by advanced solid-state 13C NMR spectroscopy

USGS Publications Warehouse

Mao, J.; Fang, X.; Lan, Y.; Schimmelmann, A.; Mastalerz, Maria; Xu, L.; Schmidt-Rohr, K.

2010-01-01

We have used advanced and quantitative solid-state nuclear magnetic resonance (NMR) techniques to investigate structural changes in a series of type II kerogen samples from the New Albany Shale across a range of maturity (vitrinite reflectance R0 from 0.29% to 1.27%). Specific functional groups such as CH3, CH2, alkyl CH, aromatic CH, aromatic C-O, and other nonprotonated aromatics, as well as "oil prone" and "gas prone" carbons, have been quantified by 13C NMR; atomic H/C and O/C ratios calculated from the NMR data agree with elemental analysis. Relationships between NMR structural parameters and vitrinite reflectance, a proxy for thermal maturity, were evaluated. The aromatic cluster size is probed in terms of the fraction of aromatic carbons that are protonated (???30%) and the average distance of aromatic C from the nearest protons in long-range H-C dephasing, both of which do not increase much with maturation, in spite of a great increase in aromaticity. The aromatic clusters in the most mature sample consist of ???30 carbons, and of ???20 carbons in the least mature samples. Proof of many links between alkyl chains and aromatic rings is provided by short-range and long-range 1H-13C correlation NMR. The alkyl segments provide most H in the samples; even at a carbon aromaticity of 83%, the fraction of aromatic H is only 38%. While aromaticity increases with thermal maturity, most other NMR structural parameters, including the aromatic C-O fractions, decrease. Aromaticity is confirmed as an excellent NMR structural parameter for assessing thermal maturity. In this series of samples, thermal maturation mostly increases aromaticity by reducing the length of the alkyl chains attached to the aromatic cores, not by pronounced growth of the size of the fused aromatic ring clusters. ?? 2010 Elsevier Ltd. All rights reserved.

COMPARISON OF THE GENOTOXIC ACTIVITIES OF THE K-REGION DIHYDRODIOL OF BENZO[A]PYRENE WITH BENZO[A]PYRENE IN MAMMALIAN CELLS: MORPHOLOGICAL CELL TRANSFORMATION; DNA DAMAGE; AND STABLE COVALENT DNA ADDUCTS

EPA Science Inventory

Benzo[a]pyrene (B[a]P) has been the most thoroughly studied polycyclic aromatic hydrocarbon (PAH) with regard to its occurrence, metabolism, toxicological and carcinogenic activities. Many mechanisms have been suggested to explain its carcinogenic activity, yet many questions sti...

Chemical and thermal stability of N-heterocyclic ionic liquids in catalytic C-H activation reactions.

PubMed

Chen, Guanyi; Kang, Shujuan; Ma, Qisheng; Chen, Weiqun; Tang, Yongchun

2014-11-01

(1)H-NMR spectrum analyses are applied to study the chemical and thermal stability of selected N-heterocyclic ionic liquids within the reaction system that can highly efficiently activate a C-H bond of methane and convert it into the C-O bond in methanol. Our results indicate that under such reaction conditions involving using a powerful Pt-based catalyst and strong acidic solvent, the aromatic ring of an imidazolium cation becomes unstable generating an ammonium ion (NH(4)(+)). Our results also suggest that the instability of the imidazolium ring is more chemically (participation in reactions) than thermally based. Modifications of the aromatic ring structure such as pyrazolium and triazolium cations can increase the chemical/thermal stability of ionic liquids under these reaction conditions. Copyright © 2014 John Wiley & Sons, Ltd.

Intermolecular hydrogen bonds in hetero-complexes of biologically active aromatic molecules probed by the methods of vibrational spectroscopy.

PubMed

Semenov, M A; Blyzniuk, Iu N; Bolbukh, T V; Shestopalova, A V; Evstigneev, M P; Maleev, V Ya

2012-09-01

By the methods of vibrational spectroscopy (Infrared and Raman) the investigation of the hetero-association of biologically active aromatic compounds: flavin-mononucleotide (FMN), ethidium bromide (EB) and proflavine (PRF) was performed in aqueous solutions. It was shown that between the functional groups (CO and NH(2)) the intermolecular hydrogen bonds are formed in the hetero-complexes FMN-EB and FMN-PRF, additionally stabilizing these structures. An estimation of the enthalpy of Н-bonding obtained from experimental shifts of carbonyl vibrational frequencies has shown that the H-bonds do not dominate in the magnitude of experimentally measured total enthalpy of the hetero-association reactions. The main stabilization is likely due to intermolecular interactions of the molecules in these complexes and their interaction with water environment. Copyright © 2012 Elsevier B.V. All rights reserved.

Steam Pyrolysis of Polyimides: Effects of Steam on Raw Material Recovery.

PubMed

Kumagai, Shogo; Hosaka, Tomoyuki; Kameda, Tomohito; Yoshioka, Toshiaki

2015-11-17

Aromatic polyimides (PIs) have excellent thermal stability, which makes them difficult to recycle, and an effective way to recycle PIs has not yet been established. In this work, steam pyrolysis of the aromatic PI Kapton was performed to investigate the recovery of useful raw materials. Steam pyrolysis significantly enhanced the gasification of Kapton at 900 °C, resulting in 1963.1 mL g(-1) of a H2 and CO rich gas. Simultaneously, highly porous activated carbon with a high BET surface area was recovered. Steam pyrolysis increased the presence of polar functional groups on the carbon surface. Thus, it was concluded that steam pyrolysis shows great promise as a recycling technique for the recovery of useful synthetic gases and activated carbon from PIs without the need for catalysts and organic solvents.

Autoantibodies against aromatic amino acid hydroxylases in patients with autoimmune polyendocrine syndrome type 1 target multiple antigenic determinants and reveal regulatory regions crucial for enzymatic activity.

PubMed

Bratland, Eirik; Magitta, Ng'weina Francis; Bøe Wolff, Anette Susanne; Ekern, Trude; Knappskog, Per Morten; Kämpe, Olle; Haavik, Jan; Husebye, Eystein Sverre

2013-06-01

Patients with autoimmune polyendocrine syndrome type 1 (APS-1) frequently have autoantibodies directed against the aromatic amino acid hydroxylases tryptophan hydroxylase (TPH) and tyrosine hydroxylase (TH). We aimed to characterize these autoantibodies with regard to their antigenic determinants, their influence on enzymatic activity and their clinical associations. In particular, we wanted to compare autoantibodies against the two different isoforms of TPH, which display different tissue distribution. Using sera from 48 Scandinavian APS-1 patients we identified 36 patients (75%) with antibodies against one or more of these three enzymes. Antibodies against TPH1, but not TPH2, were associated with malabsorption in the whole Scandinavian cohort, while TH antibodies were associated with dental enamel hypoplasia in Norwegian patients. Subsequent experiments with selected patient sera indicated that while the C-terminal domain was the immunodominant part of TPH1, the epitopes of TPH2 and TH were mainly located in the N-terminal regulatory domains. We also identified a TPH1 specific epitope involved in antibody mediated inhibition of enzyme activity, a finding that provides new insight into the enzymatic mechanisms of the aromatic amino acid hydroxylases and knowledge about structural determinants of enzyme autoantigens. In conclusion, TPH1, TPH2 and TH all have unique antigenic properties in spite of their structural similarity. Copyright © 2012 Elsevier GmbH. All rights reserved.

Designed β-Boomerang Antiendotoxic and Antimicrobial Peptides

PubMed Central

Bhunia, Anirban; Mohanram, Harini; Domadia, Prerna N.; Torres, Jaume; Bhattacharjya, Surajit

2009-01-01

Lipopolysaccharide (LPS), an integral part of the outer membrane of Gram-negative bacteria, is involved in a variety of biological processes including inflammation, septic shock, and resistance to host-defense molecules. LPS also provides an environment for folding of outer membrane proteins. In this work, we describe the structure-activity correlation of a series of 12-residue peptides in LPS. NMR structures of the peptides derived in complex with LPS reveal boomerang-like β-strand conformations that are stabilized by intimate packing between the two aromatic residues located at the 4 and 9 positions. This structural feature renders these peptides with a high ability to neutralize endotoxicity, >80% at 10 nm concentration, of LPS. Replacements of these aromatic residues either with Ala or with Leu destabilizes the boomerang structure with the concomitant loss of antiendotoxic and antimicrobial activities. Furthermore, the aromatic packing stabilizing the β-boomerang structure in LPS is found to be maintained even in a truncated octapeptide, defining a structured LPS binding motif. The mode of action of the active designed peptides correlates well with their ability to perturb LPS micelle structures. Fourier transform infrared spectroscopy studies of the peptides delineate β-type conformations and immobilization of phosphate head groups of LPS. Trp fluorescence studies demonstrated selective interactions with LPS and the depth of insertion into the LPS bilayer. Our results demonstrate the requirement of LPS-specific structures of peptides for endotoxin neutralizations. In addition, we propose that structures of these peptides may be employed to design proteins for the outer membrane. PMID:19520860

Chronic toxicity of selected polycyclic aromatic hydrocarbons to algae and crustaceans using passive dosing.

PubMed

Bragin, Gail E; Parkerton, Thomas F; Redman, Aaron D; Letinksi, Daniel J; Butler, Josh D; Paumen, Miriam Leon; Sutherland, Cary A; Knarr, Tricia M; Comber, Mike; den Haan, Klaas

2016-12-01

Because of the large number of possible aromatic hydrocarbon structures, predictive toxicity models are needed to support substance hazard and risk assessments. Calibration and evaluation of such models requires toxicity data with well-defined exposures. The present study has applied a passive dosing method to generate reliable chronic effects data for 8 polycyclic aromatic hydrocarbons (PAHs) on the green algae Pseudokirchneriella subcapitata and the crustacean Ceriodaphnia dubia. The observed toxicity of these substances on algal growth rate and neonate production were then compared with available literature toxicity data for these species, as well as target lipid model and chemical activity-based model predictions. The use of passive dosing provided well-controlled exposures that yielded more consistent data sets than attained by past literature studies. Results from the present study, which were designed to exclude the complicating influence of ultraviolet light, were found to be well described by both target lipid model and chemical activity effect models. The present study also found that the lack of chronic effects for high molecular weight PAHs was consistent with the limited chemical activity that could be achieved for these compounds in the aqueous test media. Findings from this analysis highlight that variability in past literature toxicity data for PAHs may be complicated by both poorly controlled exposures and photochemical processes that can modulate both exposure and toxicity. Environ Toxicol Chem 2016;35:2948-2957. © 2016 SETAC. © 2016 SETAC.

Relationship between hydrocarbon structure and induction of P450: effects on protein levels and enzyme activities.

PubMed

Backes, W L; Sequeira, D J; Cawley, G F; Eyer, C S

1993-12-01

1. Treatment of male rat with the small aromatic hydrocarbons, benzene, toluene, ethylbenzene, n-propylbenzene, m-xylene, and p-xylene increased several P450-dependent activities, with ethylbenzene, m-xylene, and n-propylbenzene producing the greatest response. Hydrocarbon treatment differentially affected toluene metabolism, producing a response dependent on the metabolite monitored. In untreated rats, benzyl alcohol was the major hydroxylation product of toluene metabolism, comprising > 99% of the total metabolites formed. Hydrocarbon treatment increased the overall rate of toluene metabolism by dramatically increasing the amount of aromatic hydroxylation. Ethylbenzene, n-propylbenzene and m-xylene were the most effective inducers of aromatic hydroxylation of toluene. In contrast, production of the major toluene metabolite benzyl alcohol was increased only after treatment with m-xylene. 2. P450 2B1/2B2 levels were induced by each of the hydrocarbons examined, with the magnitude of induction increasing with increasing hydrocarbon size. P450 1A1 was also induced after hydrocarbon exposure; however, the degree of induction was smaller than that observed for P450 2B1/2B2. P450 2C11 levels were suppressed after treatment with benzene, ethylbenzene and n-propylbenzene. 3. Taken together these results display two induction patterns. The first generally corresponds to changes in the P450 2B subfamily, where activities (e.g. the aromatic hydroxylations of toluene) were most effectively induced by ethylbenzene, n-propylbenzene and m-xylene. In the second, induction was observed only after m-xylene treatment, a pattern that was found when the metabolism of the substrate was catalysed by both the P450 2B subfamily and P450 2C11. Hydrocarbons that both induced P450 2B1/2B2 and suppressed P450 2C11 (such as ethylbenzene and n-propylbenzene) showed little change in activities catalysed by both isozymes (e.g. aliphatic hydroxylation of toluene, and aniline hydroxylation); however, m-xylene treatment led to elevated P450 2B1/2B2 levels without significantly suppressing P450 2C11. m-Xylene produced significant increases in activities efficiently catalysed by both isozymes. Therefore, the unique induction pattern observed after m-xylene treatment can be accounted for by induction of P450 2B1/2B2 without concomitant suppression of P450 2C11.

Contribution of TyrB26 to the Function and Stability of Insulin

PubMed Central

Pandyarajan, Vijay; Phillips, Nelson B.; Rege, Nischay; Lawrence, Michael C.; Whittaker, Jonathan; Weiss, Michael A.

2016-01-01

Crystallographic studies of insulin bound to receptor domains have defined the primary hormone-receptor interface. We investigated the role of TyrB26, a conserved aromatic residue at this interface. To probe the evolutionary basis for such conservation, we constructed 18 variants at B26. Surprisingly, non-aromatic polar or charged side chains (such as Glu, Ser, or ornithine (Orn)) conferred high activity, whereas the weakest-binding analogs contained Val, Ile, and Leu substitutions. Modeling of variant complexes suggested that the B26 side chains pack within a shallow depression at the solvent-exposed periphery of the interface. This interface would disfavor large aliphatic side chains. The analogs with highest activity exhibited reduced thermodynamic stability and heightened susceptibility to fibrillation. Perturbed self-assembly was also demonstrated in studies of the charged variants (Orn and Glu); indeed, the GluB26 analog exhibited aberrant aggregation in either the presence or absence of zinc ions. Thus, although TyrB26 is part of insulin's receptor-binding surface, our results suggest that its conservation has been enjoined by the aromatic ring's contributions to native stability and self-assembly. We envisage that such classical structural relationships reflect the implicit threat of toxic misfolding (rather than hormonal function at the receptor level) as a general evolutionary determinant of extant protein sequences. PMID:27129279

CYP-450 isoenzymes catalyze the generation of hazardous aromatic amines after reaction with the azo dye Sudan III.

PubMed

Zanoni, Thalita Boldrin; Lizier, Thiago M; Assis, Marilda das Dores; Zanoni, Maria Valnice B; de Oliveira, Danielle Palma

2013-07-01

This work describes the mutagenic response of Sudan III, an adulterant food dye, using Salmonella typhimurium assay and the generation of hazardous aromatic amines after different oxidation methods of this azo dye. For that, we used metabolic activation by S9, catalytic oxidation by ironporphyrin and electrochemistry oxidation in order to simulate endogenous oxidation conditions. The oxidation reactions promoted discoloration from 65% to 95% of Sudan III at 1 × 10(-4)molL(-1) and generation of 7.6 × 10(-7)molL(-1) to 0.31 × 10(-4)molL(-1) of aniline, o-anisidine, 2-methoxi-5-methylaniline, 4-aminobiphenyl, 4,4'-oxydianiline; 4,4'-diaminodiphenylmethane and 2,6-dimethylaniline. The results were confirmed by LC-MS-MS experiments. We also correlate the mutagenic effects of Sudan III using S. typhimurium with the strain TA1535 in the presence of exogenous metabolic activation (S9) with the metabolization products of this compound. Our findings clearly indicate that aromatic amines are formed due to oxidative reactions that can be promoted by hepatic cells, after the ingestion of Sudan III. Considering that, the use of azo compounds as food dyestuffs should be carefully controlled. Copyright © 2013 Elsevier Ltd. All rights reserved.

Evaluating Activated Carbon Adsorption of Dissolved Organic Matter and Micropollutants Using Fluorescence Spectroscopy.

PubMed

Shimabuku, Kyle K; Kennedy, Anthony M; Mulhern, Riley E; Summers, R Scott

2017-03-07

Dissolved organic matter (DOM) negatively impacts granular activated carbon (GAC) adsorption of micropollutants and is a disinfection byproduct precursor. DOM from surface waters, wastewater effluent, and 1 kDa size fractions were adsorbed by GAC and characterized using fluorescence spectroscopy, UV-absorption, and size exclusion chromatography (SEC). Fluorescing DOM was preferentially adsorbed relative to UV-absorbing DOM. Humic-like fluorescence (peaks A and C) was selectively adsorbed relative to polyphenol-like fluorescence (peaks T and B) potentially due to size exclusion effects. In the surface waters and size fractions, peak C was preferentially removed relative to peak A, whereas the reverse was found in wastewater effluent, indicating that humic-like fluorescence is associated with different compounds depending on DOM source. Based on specific UV-absorption (SUVA), aromatic DOM was preferentially adsorbed. The fluorescence index (FI), if interpreted as an indicator of aromaticity, indicated the opposite but exhibited a strong relationship with average molecular weight, suggesting that FI might be a better indicator of DOM size than aromaticity. The influence of DOM intermolecular interactions on adsorption were minimal based on SEC analysis. Fluorescence parameters captured the impact of DOM size on the fouling of 2-methylisoborneol and warfarin adsorption and correlated with direct competition and pore blockage indicators.

Novel Scheme for Biosynthesis of Aryl Metabolites from l-Phenylalanine in the Fungus Bjerkandera adusta

PubMed Central

Lapadatescu, Carmen; Giniès, Christian; Le Quéré, Jean-Luc; Bonnarme, Pascal

2000-01-01

Aryl metabolite biosynthesis was studied in the white rot fungus Bjerkandera adusta cultivated in a liquid medium supplemented with l-phenylalanine. Aromatic compounds were analyzed by gas chromatography-mass spectrometry following addition of labelled precursors (14C- and 13C-labelled l-phenylalanine), which did not interfere with fungal metabolism. The major aromatic compounds identified were benzyl alcohol, benzaldehyde (bitter almond aroma), and benzoic acid. Hydroxy- and methoxybenzylic compounds (alcohols, aldehydes, and acids) were also found in fungal cultures. Intracellular enzymatic activities (phenylalanine ammonia lyase, aryl-alcohol oxidase, aryl-alcohol dehydrogenase, aryl-aldehyde dehydrogenase, lignin peroxidase) and extracellular enzymatic activities (aryl-alcohol oxidase, lignin peroxidase), as well as aromatic compounds, were detected in B. adusta cultures. Metabolite formation required de novo protein biosynthesis. Our results show that l-phenylalanine was deaminated to trans-cinnamic acid by a phenylalanine ammonia lyase and trans-cinnamic acid was in turn converted to aromatic acids (phenylpyruvic, phenylacetic, mandelic, and benzoylformic acids); benzaldehyde was a metabolic intermediate. These acids were transformed into benzaldehyde, benzyl alcohol, and benzoic acid. Our findings support the hypothesis that all of these compounds are intermediates in the biosynthetic pathway from l-phenylalanine to aryl metabolites. Additionally, trans-cinnamic acid can also be transformed via β-oxidation to benzoic acid. This was confirmed by the presence of acetophenone as a β-oxidation degradation intermediate. To our knowledge, this is the first time that a β-oxidation sequence leading to benzoic acid synthesis has been found in a white rot fungus. A novel metabolic scheme for biosynthesis of aryl metabolites from l-phenylalanine is proposed. PMID:10742235

Noncomparative scaling of aromaticity through electron itinerancy

NASA Astrophysics Data System (ADS)

Paul, Satadal; Goswami, Tamal; Misra, Anirban

2015-10-01

Aromaticity is a multidimensional concept and not a directly observable. These facts have always stood in the way of developing an appropriate theoretical framework for scaling of aromaticity. In the present work, a quantitative account of aromaticity is developed on the basis of cyclic delocalization of π-electrons, which is the phenomenon leading to unique features of aromatic molecules. The stabilization in molecular energy, caused by delocalization of π-electrons is obtained as a second order perturbation energy for archetypal aromatic systems. The final expression parameterizes the aromatic stabilization energy in terms of atom to atom charge transfer integral, onsite repulsion energy and the population of spin orbitals at each site in the delocalized π-electrons. An appropriate computational platform is framed to compute each and individual parameter in the derived equation. The numerical values of aromatic stabilization energies obtained for various aromatic molecules are found to be in close agreement with available theoretical and experimental reports. Thus the reliable estimate of aromaticity through the proposed formalism renders it as a useful tool for the direct assessment of aromaticity, which has been a long standing problem in chemistry.

Facile synthesis of unsymmetrical acridines and phenazines by a Rh(III)-catalyzed amination/cyclization/aromatization cascade.

PubMed

Lian, Yajing; Hummel, Joshua R; Bergman, Robert G; Ellman, Jonathan A

2013-08-28

We report formal [3 + 3] annulations of aromatic azides with aromatic imines and azobenzenes to give acridines and phenazines, respectively. These transformations proceed through a cascade process of Rh(III)-catalyzed amination followed by intramolecular electrophilic aromatic substitution and aromatization. Acridines can be directly prepared from aromatic aldehydes by in situ imine formation using catalytic benzylamine.

'Green incubation': avian offspring benefit from aromatic nest herbs through improved parental incubation behaviour.

PubMed

Gwinner, Helga; Capilla-Lasheras, Pablo; Cooper, Caren; Helm, Barbara

2018-06-13

Development of avian embryos requires thermal energy, usually from parents. Parents may, however, trade off catering for embryonic requirements against their own need to forage through intermittent incubation. This dynamically adjusted behaviour can be affected by properties of the nest. Here, we experimentally show a novel mechanism by which parents, through incorporation of aromatic herbs into nests, effectively modify their incubation behaviour to the benefit of their offspring. Our study species, the European starling, includes in its nest aromatic herbs which promote offspring fitness. We provided wild starlings with artificial nests including or excluding the typically selected fresh herbs and found strong support for our prediction of facilitated incubation. Herb effects were not explained by thermal changes of the nests per se , but by modified parental behaviours. Egg temperatures and nest attendance were higher in herb than herbless nests, egg temperatures dropped less frequently below critical thresholds and parents started their active day earlier. These effects were dynamic over time and particularly strong during early incubation. Incubation period was shorter in herb nests, and nestlings were heavier one week after hatching. Aromatic herbs hence influenced incubation in beneficial ways for offspring, possibly through pharmacological effects on incubating parents. © 2018 The Author(s).

One-step hydroprocessing of fatty acids into renewable aromatic hydrocarbons over Ni/HZSM-5: insights into the major reaction pathways.

PubMed

Xing, Shiyou; Lv, Pengmei; Wang, Jiayan; Fu, Junying; Fan, Pei; Yang, Lingmei; Yang, Gaixiu; Yuan, Zhenhong; Chen, Yong

2017-01-25

For high caloricity and stability in bio-aviation fuels, a certain content of aromatic hydrocarbons (AHCs, 8-25 wt%) is crucial. Fatty acids, obtained from waste or inedible oils, are a renewable and economic feedstock for AHC production. Considerable amounts of AHCs, up to 64.61 wt%, were produced through the one-step hydroprocessing of fatty acids over Ni/HZSM-5 catalysts. Hydrogenation, hydrocracking, and aromatization constituted the principal AHC formation processes. At a lower temperature, fatty acids were first hydrosaturated and then hydrodeoxygenated at metal sites to form long-chain hydrocarbons. Alternatively, the unsaturated fatty acids could be directly deoxygenated at acid sites without first being saturated. The long-chain hydrocarbons were cracked into gases such as ethane, propane, and C 6 -C 8 olefins over the catalysts' Brønsted acid sites; these underwent Diels-Alder reactions on the catalysts' Lewis acid sites to form AHCs. C 6 -C 8 olefins were determined as critical intermediates for AHC formation. As the Ni content in the catalyst increased, the Brønsted-acid site density was reduced due to coverage by the metal nanoparticles. Good performance was achieved with a loading of 10 wt% Ni, where the Ni nanoparticles exhibited a polyhedral morphology which exposed more active sites for aromatization.

Human Immunodeficiency Virus Type 1 cDNA Integration: New Aromatic Hydroxylated Inhibitors and Studies of the Inhibition Mechanism

PubMed Central

Farnet, C. M.; Wang, B.; Hansen, M.; Lipford, J. R.; Zalkow, L.; Robinson, W. E.; Siegel, J.; Bushman, F.

1998-01-01

Integration of the human immunodeficiency virus type 1 (HIV-1) cDNA is a required step for viral replication. Integrase, the virus-encoded enzyme important for integration, has not yet been exploited as a target for clinically useful inhibitors. Here we report on the identification of new polyhydroxylated aromatic inhibitors of integrase including ellagic acid, purpurogallin, 4,8,12-trioxatricornan, and hypericin, the last of which is known to inhibit viral replication. These compounds and others were characterized in assays with subviral preintegration complexes (PICs) isolated from HIV-1-infected cells. Hypericin was found to inhibit PIC assays, while the other compounds tested were inactive. Counterscreening of these and other integrase inhibitors against additional DNA-modifying enzymes revealed that none of the polyhydroxylated aromatic compounds are active against enzymes that do not require metals (methylases, a pox virus topoisomerase). However, all were cross-reactive with metal-requiring enzymes (restriction enzymes, a reverse transcriptase), implicating metal atoms in the inhibitory mechanism. In mechanistic studies, we localized binding of some inhibitors to the catalytic domain of integrase by assaying competition of binding by labeled nucleotides. These findings help elucidate the mechanism of action of the polyhydroxylated aromatic inhibitors and provide practical guidance for further inhibitor development. PMID:9736543

Toxic effects of unresolved complex mixtures of aromatic hydrocarbons accumulated by mussels, Mytilus edulis, from contaminated field sites.

PubMed

Donkin, Peter; Smith, Emma L; Rowland, Steven J

2003-11-01

Exposure of marine mussels (Mytilus edulis) to an unresolved complex mixture (UCM) of aromatic hydrocarbons isolated from a crude oil has been shown to reduce their feeding rate by 40%. The present study was undertaken to determine whether UCMs bioaccumulated by mussels in the field are also toxic. The feeding rate of mussels derived from polluted sites increased when they were placed in clean water, pointing to a loss of toxic agents from the tissues. At the end of the depuration period, water in which mussels from an oil-polluted site had been held contained a UCM. Steam-distillation extracts of the tissues of mussels taken from several polluted sites were shown to be highly toxic to the feeding activity of juvenile mussels. The tissues of mussels from these sites contained UCMs. Nontoxic steam distillates from clean mussels did not. Steam-distillation extracts of mussels from an oil-polluted site were fractionated by normal-phase high-performance liquid chromatography. A fraction, largely comprising a "monoaromatic" UCM, reduced the feeding rate of juvenile mussels by 70%. Two later-eluting fractions containing aromatic UCMs also produced smaller depressions in feeding rate. These results support our contention that some aromatic UCM hydrocarbons constitute a forgotten pollutant burden in the marine environment.

Combined Experimental and Theoretical Investigations on Optical Activities of Möbius Aromatic and Möbius Antiaromatic Hexaphyrin Phosphorus Complexes.

PubMed

Mori, Tadashi; Tanaka, Takayuki; Higashino, Tomohiro; Yoshida, Kota; Osuka, Atsuhiro

2016-06-23

Intrinsically chiral Möbius aromatic [28]hexaphyrin monophosphorus(V) and Möbius antiaromatic [30]hexaphyrin bisphosphorus(V) complexes have been optically resolved and their absolute configurations (ACs) were determined by combined experimental and theoretical investigations on their circular dichroisms (CDs). First elutes in chiral HPLC exhibited strong positive Cotton effects (CEs) at the B-band, characteristic for the ML configurations in their Möbius strips. Weak CEs at the Q-band, if attainable, complemented their AC assignment. The whole CD pattern and intensity were well reproduced by time-dependent approximate coupled cluster theory using model systems that omit five outward meso-aryl substituents (inward-meso-retained model), providing a solid basis for AC assignment. The cost efficient TD-DFT method with appropriate functionals for fully substituted (nontruncated) complexes well reproduced CEs around the B-band (but less satisfactory at the Q-band), also allows the rapid AC estimation for their Möbius strips. Observed difference in CDs between aromatic and antiaromatic hexaphyrins were better interpreted by their shifts in energy levels and altered interactions of relevant molecular orbitals, rather than small differences in Möbius geometries nor aromatic/antiaromatic character, despite the correlations recently claimed in planar π-systems.

A phenylalanine rotameric switch for signal-state control in bacterial chemoreceptors

NASA Astrophysics Data System (ADS)

Ortega, Davi R.; Yang, Chen; Ames, Peter; Baudry, Jerome; Parkinson, John S.; Zhulin, Igor B.

2013-12-01

Bacterial chemoreceptors are widely used as a model system for elucidating the molecular mechanisms of transmembrane signalling and have provided a detailed understanding of how ligand binding by the receptor modulates the activity of its associated kinase CheA. However, the mechanisms by which conformational signals move between signalling elements within a receptor dimer and how they control kinase activity remain unknown. Here, using long molecular dynamics simulations, we show that the kinase-activating cytoplasmic tip of the chemoreceptor fluctuates between two stable conformations in a signal-dependent manner. A highly conserved residue, Phe396, appears to serve as the conformational switch, because flipping of the stacked aromatic rings of an interacting F396-F396‧ pair in the receptor homodimer takes place concomitantly with the signal-related conformational changes. We suggest that interacting aromatic residues, which are common stabilizers of protein tertiary structure, might serve as rotameric molecular switches in other biological processes as well.

Three-component, one-pot synthesis of anthranilamide Schiff bases bearing 4-aminoquinoline moiety as Mycobacterium tuberculosis gyrase inhibitors.

PubMed

Salve, Preeti S; Alegaon, Shankar G; Sriram, Dharmarajan

2017-04-15

An efficient three-component, one-pot protocol is described for the synthesis of biologically interesting 2-(benzylideneamino)-N-(7-chloroquinolin-4-yl)benzohydrazide derivatives from isatoic anhydride, 7-chloro-4-hydrazinylquinoline and aromatic and/or hetero aromatic aldehydes under catalyst free condensation by using water as reaction media. All synthesized compounds were evaluated for their antimycobacterial activity against Mycobacterium tuberculosis (MTB) and cytotoxicity activity against normal VERO cell lines. The synthesized compounds exhibited minimum inhibitory concentration (MIC) ranging from 0.78 to 25μM. Among the tested compounds 4c, 4o, 4r, and 4u exhibited promising inhibitory activity (MIC=3.12μM). Compounds 4h and 4i stand out, showing MIC values of 0.78 and 1.56μM respectively. Both compounds were further screened for their Mycobacterium tuberculosis DNA gyrase inhibitory assay which suggested that these compounds have a great potential for further optimization and development as antitubercular agents. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effect of beer marinades on formation of polycyclic aromatic hydrocarbons in charcoal-grilled pork.

PubMed

Viegas, Olga; Yebra-Pimentel, Iria; Martínez-Carballo, Elena; Simal-Gandara, Jesus; Ferreira, Isabel M P L V O

2014-03-26

The effect of marinating meat with Pilsner beer, nonalcoholic Pilsner beer, and Black beer (coded respectively PB, P0B, and BB) on the formation of polycyclic aromatic hydrocarbons (PAHs) in charcoal-grilled pork was evaluated and compared with the formation of these compounds in unmarinated meat. Antiradical activity of marinades (DPPH assay) was assayed. BB exhibited the strongest scavenging activity (68.0%), followed by P0B (36.5%) and PB (29.5%). Control and marinated meat samples contained the eight PAHs named PAH8 by the EFSA and classified as suitable indicators for carcinogenic potency of PAHs in food. BB showed the highest inhibitory effect in the formation of PAH8 (53%), followed by P0B (25%) and PB (13%). The inhibitory effect of beer marinades on PAH8 increased with the increase of their radical-scavenging activity. BB marinade was the most efficient on reduction of PAH formation, providing a proper mitigation strategy.

Selective treatment to reduce contamination of propolis by polycyclic aromatic hydrocarbons (PAHs) still preserving its active polyphenol component and antioxidant activity.

PubMed

Galeotti, Fabio; Crimaldi, Laura; Maccari, Francesca; Zaccaria, Vincenzo; Fachini, Alfredo; Volpi, Nicola

2017-09-01

The adverse effects on health and environment caused by polycyclic aromatic hydrocarbons (PAHs) are critical problems. EFSA has defined 16 priority PAHs that are both genotoxic and carcinogenic, and identified eight (PAH8) priority PAHs as good indicators of the toxicity and occurrence in food. Food supplements containing propolis were also found to contain relatively high quantities of PAHs. We report about an extractive procedure which is able to purify propolis from a high content of PAHs using a balanced mixture of ethanol and water solvents. Extracts were characterised for total content of polyphenols, for in vitro antioxidant activity, and single classes of polyphenols evaluated by HPLC-ESI-MS. Obtained propolis extracts were found to have PAH8 and specific benzo[a]pyrene content below limits recommended by EFSA. The reported extractive procedure is easily applicable for possible industrial productions and may also be adopted to the purification of polyphenols from other plant extracts and natural sources.

Gas Chromatography-Mass Spectrometry-Olfactometry To Control the Aroma Fingerprint of Extra Virgin Olive Oil from Three Tunisian Cultivars at Three Harvest Times.

PubMed

Ben Brahim, Samia; Amanpour, Asghar; Chtourou, Fatma; Kelebek, Hasim; Selli, Serkan; Bouaziz, Mohamed

2018-03-21

Gas chromatography-mass spectrometry-olfactometry was used for the analysis of volatile compounds and key odorants of three less studied Tunisian olive oil cultivars for the first time. A total of 42 aroma compounds were identified and quantified in extra virgin olive oils. The present study revealed that the most dominant volatiles in olive oil samples qualitatively and quantitatively were aldehydes and alcohols, followed by terpenes and esters. Indeed, chemometric analysis has shown a correlation between chemical compounds and sensory properties. The determination of aroma-active compounds of olive oil samples was carried out using aroma extract dilution analysis. A total of 15 aroma-active compounds were detected in the aromatic extract of extra virgin olive oil, of which 14 were identified. On the basis of the flavor dilution (FD) factor, the most potent aromatic active compound was hexanal (FD = 512) in Fakhari olive oil, (FD = 256) in Touffehi oils, and (FD = 128) in Jemri olive oil.

Effect of torrefaction on the properties of rice straw high temperature pyrolysis char: Pore structure, aromaticity and gasification activity.

PubMed

Chen, Handing; Chen, Xueli; Qin, Yueqiang; Wei, Juntao; Liu, Haifeng

2017-03-01

The influence of torrefaction on the physicochemical characteristics of char during raw and water washed rice straw pyrolysis at 800-1200°C is investigated. Pore structure, aromaticity and gasification activity of pyrolysis chars are compared between raw and torrefied samples. For raw straw, BET specific surface area decreases with the increased torrefaction temperature at the same pyrolysis temperature and it approximately increases linearly with weight loss during pyrolysis. The different pore structure evolutions relate to the different volatile matters and pore structures between raw and torrefied straw. Torrefaction at higher temperature would bring about a lower graphitization degree of char during pyrolysis of raw straw. Pore structure and carbon crystalline structure evolutions of raw and torrefied water washed straw are different from these of raw straw during pyrolysis. For both raw and water washed straw, CO 2 gasification activities of pyrolysis chars are different between raw and torrefied samples. Copyright © 2016 Elsevier Ltd. All rights reserved.

Syntheses of cytotoxic novel arctigenin derivatives bearing halogen and alkyl groups on aromatic rings.

PubMed

Yamauchi, Satoshi; Wukirsari, Tuti; Ochi, Yoshiaki; Nishiwaki, Hisashi; Nishi, Kosuke; Sugahara, Takuya; Akiyama, Koichi; Kishida, Taro

2017-09-01

The new lignano-9,9'-lactones (α,β-dibenzyl-γ-butyrolactone lignans), which showed the higher cytotoxicity than arctigenin, were synthesized. The well-known cytotoxic arctigenin showed activity against HL-60 cells (EC 50 =12μM), however, it was inactive against HeLa cells (EC 50 >100μM). The synthesized (3,4-dichloro, 2'-butoxy)-derivative 55 and (3,4-dichloro, 4'-butyl)-derivative 66 bearing the lignano-9,9'-lactone structures showed the EC 50 values of 10μM and 9.4μM against HL-60 cells, respectively. Against HeLa cells, the EC 50 value of the derivative 66 was 27μM. By comparing the activities with the corresponding 9,9'-epoxy structure (tetrahydrofuran compounds), the importance of the lactone structure of 55 and 66 for the higher activities was shown. The substituents on the aromatic ring of the lignano-9,9'-lactones affected the cytotoxicity level, observing more than 10-fold difference. Copyright © 2017. Published by Elsevier Ltd.

Delayed myelosuppression with acute exposure to hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and environmental degradation product hexahydro-1-nitroso-3,5-dinitro-1,3,5-triazine (MNX) in rats

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jaligama, Sridhar; Kale, Vijay M.; Wilbanks, Mitchell S.

2013-02-01

Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), a widely used munitions compound, and hexahydro-1-nitroso-3,5-dinitro-1,3,5-triazine (MNX), its N-nitroso product of anaerobic microbial nitroreduction, are contaminants of military sites. Previous studies have shown MNX to be the most acutely toxic among the nitroreduced degradation products of RDX and to cause mild anemia at high dose. The present study compares hematotoxicity with acute oral exposure to MNX with parent RDX. Both RDX and MNX caused a modest decrease in blood hemoglobin and ∼ 50% loss of granulocytes (NOAELs = 47 mg/kg) in female Sprague–Dawley rats observed 14 days post-exposure. We explored the possibility that blood cell loss observedmore » after 14 days was delayed in onset because of toxicity to bone marrow (BM) progenitors. RDX and MNX decreased granulocyte/macrophage-colony forming cells (GM-CFCs) at 14, but not 7, days (NOAELs = 24 mg/kg). The earliest observed time at which MNX decreased GM-CFCs was 10 days post-exposure. RDX and MNX likewise decreased BM burst-forming units-erythroid (BFU-Es) at 14, but not 7, days. Granulocyte–erythrocyte–monocyte–megakaryocyte (GEMM)-CFCs were unaffected by RDX and MNX at 7 days suggesting precursor depletion did not account for GM-CFC and BFU-E loss. MNX added to the culture media was without effect on GM-CFC formation indicating no direct inhibition. Flow cytometry showed no differential loss of BM multilineage progenitors (Thy1.1{sup +}) or erythroid (CD71{sup +}) precursors with MNX suggesting myeloid and erythroid lineages were comparably affected. Collectively, these data indicate that acute exposure to both RDX and MNX caused delayed suppression of myelo- and erythropoiesis with subsequent decrease of peripheral granulocytes and erythrocytes. Highlights: ► Acute oral exposure to munitions RDX causes myelosuppression. ► Environmental degradation product MNX is comparable in effect. ► RDX and MNX are cytotoxic to both myeloid and erythroid progenitor cells. ► Myelosuppression is delayed in onset by > 7 days after single exposure.« less

Facile Synthesis of Unsymmetrical Acridines and Phenazines by a Rhodium(III)-Catalyzed Amination, Cyclization and Aromatization Cascade

PubMed Central

Lian, Yajing; Hummel, Joshua R.; Bergman, Robert G.; Ellman, Jonathan A.

2013-01-01

New formal [3 + 3] annulations have been developed to obtain acridines and phenazines from aromatic azides and aromatic imines and azobenzenes, respectively. These transformations proceed through a cascade process of Rh(III)-catalyzed amination followed by intramolecular electrophilic aromatic substitution and aromatization. Acridines can be directly prepared from aromatic aldehydes by in situ imine formation using catalytic benzylamine. PMID:23957711

Identification of Genes and Pathways Related to Phenol Degradation in Metagenomic Libraries from Petroleum Refinery Wastewater

PubMed Central

Silva, Cynthia C.; Hayden, Helen; Sawbridge, Tim; Mele, Pauline; De Paula, Sérgio O.; Silva, Lívia C. F.; Vidigal, Pedro M. P.; Vicentini, Renato; Sousa, Maíra P.; Torres, Ana Paula R.; Santiago, Vânia M. J.; Oliveira, Valéria M.

2013-01-01

Two fosmid libraries, totaling 13,200 clones, were obtained from bioreactor sludge of petroleum refinery wastewater treatment system. The library screening based on PCR and biological activity assays revealed more than 400 positive clones for phenol degradation. From these, 100 clones were randomly selected for pyrosequencing in order to evaluate the genetic potential of the microorganisms present in wastewater treatment plant for biodegradation, focusing mainly on novel genes and pathways of phenol and aromatic compound degradation. The sequence analysis of selected clones yielded 129,635 reads at an estimated 17-fold coverage. The phylogenetic analysis showed Burkholderiales and Rhodocyclales as the most abundant orders among the selected fosmid clones. The MG-RAST analysis revealed a broad metabolic profile with important functions for wastewater treatment, including metabolism of aromatic compounds, nitrogen, sulphur and phosphorus. The predicted 2,276 proteins included phenol hydroxylases and cathecol 2,3- dioxygenases, involved in the catabolism of aromatic compounds, such as phenol, byphenol, benzoate and phenylpropanoid. The sequencing of one fosmid insert of 33 kb unraveled the gene that permitted the host, Escherichia coli EPI300, to grow in the presence of aromatic compounds. Additionally, the comparison of the whole fosmid sequence against bacterial genomes deposited in GenBank showed that about 90% of sequence showed no identity to known sequences of Proteobacteria deposited in the NCBI database. This study surveyed the functional potential of fosmid clones for aromatic compound degradation and contributed to our knowledge of the biodegradative capacity and pathways of microbial assemblages present in refinery wastewater treatment system. PMID:23637911

Toward engineering E. coli with an autoregulatory system for lignin valorization

PubMed Central

Wu, Weihua; Liu, Fang; Singh, Seema

2018-01-01

Efficient lignin valorization could add more than 10-fold the value gained from burning it for energy and is critical for economic viability of future biorefineries. However, lignin-derived aromatics from biomass pretreatment are known to be potent fermentation inhibitors in microbial production of fuels and other value-added chemicals. In addition, isopropyl-β-d-1-thiogalactopyranoside and other inducers are routinely added into fermentation broth to induce the expression of pathway enzymes, which further adds to the overall process cost. An autoregulatory system that can diminish the aromatics’ toxicity as well as be substrate-inducible can be the key for successful integration of lignin valorization into future lignocellulosic biorefineries. Toward that goal, in this study an autoregulatory system is demonstrated that alleviates the toxicity issue and eliminates the cost of an external inducer. Specifically, this system is composed of a catechol biosynthesis pathway coexpressed with an active aromatic transporter CouP under induction by a vanillin self-inducible promoter, ADH7, to effectively convert the lignin-derived aromatics into value-added chemicals using Escherichia coli as a host. The constructed autoregulatory system can efficiently transport vanillin across the cell membrane and convert it to catechol. Compared with the system without CouP expression, the expression of catechol biosynthesis pathway with transporter CouP significantly improved the catechol yields about 30% and 40% under promoter pTrc and ADH7, respectively. This study demonstrated an aromatic-induced autoregulatory system that enabled conversion of lignin-derived aromatics into catechol without the addition of any costly, external inducers, providing a promising and economically viable route for lignin valorization. PMID:29500185

Antioxidant and Anti-Osteoporotic Activities of Aromatic Compounds and Sterols from Hericium erinaceum.

PubMed

Li, Wei; Lee, Sang Hyun; Jang, Hae Dong; Ma, Jin Yeul; Kim, Young Ho

2017-01-11

Hericium erinaceum , commonly called lion's mane mushroom, is a traditional edible mushroom widely used in culinary applications and herbal medicines in East Asian countries. In this study, a new sterol, cerevisterol 6-cinnamate ( 6 ), was isolated from the fruiting bodies of H. erinaceum together with five aromatic compounds 1 - 5 and five sterols 7 - 11 . The chemical structures of these compounds were elucidated using chemical and physical methods and comparison of HRESIMS, ¹D-NMR (¹H, 13 C, and DEPT) and 2D-NMR (COSY, HMQC, HMBC, and NOESY) spectra with previously reported data. The antioxidant and anti-osteoporotic activities of extracts and the isolated compounds 1 - 11 were investigated. All compounds exhibited peroxyl radical-scavenging capacity but only compounds 1 , 3 , and 4 showed potent reducing capacity. Moreover, compounds 1 , 2 , 4 , and 5 showed moderate effects on cellular antioxidant activity and inhibited the receptor activator of nuclear factor κB ligand (RANKL)-induced osteoclastic differentiation. These results suggested that H. erinaceum could be utilized in the development of natural antioxidant and anti-osteoporotic nutraceuticals and functional foods.

[Polycyclic aromatic hydrocarbons (PAHs) in herbs and fruit teas].

PubMed

Ciemniak, Artur

2005-01-01

Polycyclic aromatic hydrocarbons (PAHs) of which benzo[a]pyrene is the most commonly studied and measured, are fused - ring aromatic compounds formed in both natural and man made processes and are found widely distributed throughout the human environment. PAHs occur as contaminants in different food categories and beverages including water, vegetables, fruit, cereals, oils and fats, barbecued and smoked meat. The sources of PAHs in food are predominantly from environmental pollution and food processing. PAHs emissions from automobile traffic and industry activities were show to influence the PAHs levels in vegetables and fruits. The present study was carried out to determine levels of 16 basic PAHs in herbs and fruit teas. The method was based on the hexane extraction and cleaned up by florisil cartridge. The extracts were analysed by GC-MS. The levels of total PAHs varied from 48,27 microg/kg (hibiscus tea) to 1703 microg/kg (green tea). The highest level of BaP was found in lime tea (74,2 microg/kg).

Birds and polycyclic aromatic hydrocarbons

USGS Publications Warehouse

Albers, P.H.

2006-01-01

Polycyclic aromatic hydrocarbons (PAH) are present throughout the global environment and are produced naturally and by activities of humans. Effects of PAH on birds have been determined by studies employing egg injection, egg immersion, egg shell application, single and multiple oral doses, subcutaneous injection, and chemical analysis of field-collected eggs and tissue. The four-to six-ring aromatic compounds are the most toxic to embryos, young birds, and adult birds. For embryos, effects include death, developmental abnormalities, and a variety of cellular and biochemical responses. For adult and young birds, effects include reduced egg production and hatching, increased clutch or brood abandonment, reduced growth, increased organweights, and a variety of biochemical responses. Trophic level accumulation is unlikely. Environmental exposure to PAH in areas of high human population or habitats affected by recent petroleum spills might be sufficient to adversely affect reproduction. Evidence of long-term effects of elevated concentrations of environmental PAH on bird populations is very limited and the mechanisms of effect are unclear.

Aerobic sludge granulation for simultaneous anaerobic decolorization and aerobic aromatic amines mineralization for azo dye wastewater treatment.

PubMed

Yan, Lawrence K Q; Fung, Ka Y; Ng, Ka M

2018-06-01

In this study, the capability of using aerobic granules to undergo simultaneous anaerobic decolorization and aerobic aromatic amines degradation was demonstrated for azo dye wastewater treatment. An integrated acclimation-granulation process was devised, with Mordant Orange 1 as the model pollutant. Performance tests were carried out in a batch column reactor to evaluate the effect of various operating parameters. The optimal condition was to use 1.0-1.7 mm (1.51 ± 0.33 mm) granules, 5 g/L biomass, and 4000 mg/L organics as nutrient; and supplement the wastewater with 1  mg/L dissolved oxygen. This led to a dye mineralization of 61 ± 2%, an anaerobic dye removal of 88 ± 1%, and an aerobic aromatic amines removal of 70 ± 3% within 48 h. This study showed that simultaneous anaerobic/aerobic process by aerobic granules could be a possible alternative to the conventional activated sludge process.

MICROBIAL METABOLISM OF AROMATIC COMPOUNDS I.

PubMed Central

Tabak, Henry H.; Chambers, Cecil W.; Kabler, Paul W.

1964-01-01

Tabak, Henry H. (Robert A. Taft Sanitary Engineering Center, Cincinnati, Ohio), Cecil W. Chambers, and Paul W. Kabler. Microbial metabolism of aromatic carbon compounds. I. Decomposition of phenolic compounds and aromatic hydrocarbons by phenol-adapted bacteria. J. Bacteriol. 87:910–919. 1964.—Bacteria from soil and related environments were selected or adapted to metabolize phenol, hydroxy phenols, nitrophenols, chlorophenols, methylphenols, alkylphenols, and arylphenols when cultured in mineral salts media with the specific substrate as the sole source of carbon. A phenol-adapted culture (substrate-induced enzyme synthesis proven) was challenged in respirometric tests with 104 related compounds; probable significant oxidative activity occurred with 65. Dihydric phenols were generally oxidized; trihydric phenols were not. Cresols and dimethylphenols were oxidized; adding a chloro group increased resistance. Benzoic and hydroxybenzoic acids were oxidized; sulfonated, methoxylated, nitro, and chlorobenzoic acids were not; m-toluic acid was utilized but not the o- and p-isomers. Benzaldehyde and p-hydroxybenzaldehyde were oxidized. In general, nitro- and chloro-substituted compounds and the benzenes were difficult to oxidize. PMID:14137630

Metabolic engineering of the shikimate pathway

DOEpatents

Juminaga, Darmawi; Keasling, Jay D.

2017-01-10

The present disclosure relates to engineered microorganisms that produce amino acids and amino acid intermediates. In particular, the disclosure relates to recombinant nucleic acids encoding operons that increase production of aromatic amino acids and the aromatic amino acid intermediate shikimate; microorganisms with increased production of aromatic amino acids and the aromatic amino acid intermediate shikimate; and methods related to the production of aromatic amino acids, the aromatic amino acid intermediate shikimate, and commodity chemicals derived therefrom.

Role of methyl group number on SOA formation from aromatic hydrocarbons photooxidation under low NOx conditions

NASA Astrophysics Data System (ADS)

Li, L.; Tang, P.; Nakao, S.; Chen, C.-L.; Cocker, D. R., III

2015-11-01

Substitution of methyl groups onto the aromatic ring determines the SOA formation from the aromatic hydrocarbon precursor. This study links the number of methyl groups on the aromatic ring to SOA formation from aromatic hydrocarbons photooxidation under low NOx conditions (HC / NO > 10 ppb C : ppb). Aromatic hydrocarbons with increasing numbers of methyl groups are systematically studied. SOA formation from pentamethylbenzene and hexamethylbenzene are reported for the first time. A decreasing SOA yield with increasing number of methyl groups is observed. Linear trends are found in both f44 vs. f43 and O / C vs. H / C for SOA from aromatic hydrocarbons with zero to six methyl groups. An SOA oxidation state predictive method based on benzene is used to examine the effect of added methyl groups on aromatic oxidation under low NOx conditions. Further, the impact of methyl group number on density and volatility of SOA from aromatic hydrocarbons is explored. Finally, a mechanism for methyl group impact on SOA formation is suggested. Overall, this work suggests as more methyl groups are attached on the aromatic ring, SOA products from these aromatic hydrocarbons become less oxidized per mass/carbon.

Molecular aspects of aromatic C additions to soils: Implications of char quality for ecosystem functionality

NASA Astrophysics Data System (ADS)

Keiluweit, M.; Nico, P. S.; Johnson, M. G.; Kleber, M.

2009-12-01

Solid residues of incomplete combustion (biochar or char) are continuously being added to soils due to natural vegetation fires in many ecosystems. However, new strategies for carbon sequestration in soils are likely to include the active addition of biochar to soils. Since biochar is a highly aromatic organic material such additions will modify the native molecular structure of soil organic matter and thus alter interactions with the global atmosphere and hydrosphere. Here we present a molecular level assessment of the physical organization and chemical complexity of biomass-derived chars and, specifically, that of aromatic carbon in char structures. Differences among wood and grass charred at temperatures from 100 to 700°C are investigated. BET-N2 surface area, X-ray diffraction (XRD), synchrotron-based Near-edge X-ray Absorption Fine Structure (NEXAFS) and Fourier transform infrared (FT-IR) spectroscopy results demonstrate how the two plant precursor materials undergo analogous, but quantitatively different physical-chemical transitions as charring intensity increases. These changes suggest the existence of four distinct physical and chemical categories of char. We find that each category of char consists of a unique mixture of chemical phases and physical states: (i) in transition chars the crystalline character of the precursor materials is preserved, (ii) in amorphous chars the heat-altered molecules and incipient aromatic polycondensates are randomly mixed, (iii) composite chars consist of poorly ordered graphene stacks embedded in amorphous phases, and (iv) turbostratic chars are dominated by turbostratic (disordered) graphitic crystallites. There is wide variation in both the chemical and the physical nature of aromatic carbon among these char categories. In this presentation we will point out how molecular variations among the aromatic components of the different char categories translate into differences in their ability to: (i) persist in the environment, (ii) function as environmental sorbents, and (iii) to enable the soil to provide environmental services.

Quantifying reactivity for electrophilic aromatic substitution reactions with Hirshfeld charge.

PubMed

Liu, Shubin

2015-03-26

An electrophilic aromatic substitution is a process where one atom or group on an aromatic ring is replaced by an incoming electrophile. The reactivity and regioselectivity of this category of reactions is significantly impacted by the group that is already attached to the aromatic ring. Groups promoting substitution at the ortho/para and meta position are called ortho/para and meta directing groups, respectively. Earlier, we have shown that regioselectivity of the electrophilic aromatic substitution is dictated by the nucleophilicity of the substituted aromatic ring, which is proportional to the Hirshfeld charge on the regioselective site. Ortho/para directing groups have the largest negative charge values at the ortho/para positions, whereas meta directing groups often have the largest negative charge value at the meta position. The electron donation or acceptance feature of a substitution group is irrelevant to the regioselectivity. In this contribution, we extend our previous study by quantifying the reactivity for this kind of reactions. To that end, we examine the transition-state structure and activation energy of an identity reaction for a series of monosubstituted-benzene molecules reacting with hydrogen fluoride using BF3 as the catalyst in the gas phase. A total of 18 substitution groups will be considered, nine of which are ortho/para directing and the other nine groups meta directing. From this study, we found that the barrier height of these reactions strongly correlates with the Hirshfeld charge on the regioselective site for both ortho/para and meta directing groups, with the correlation coefficient R(2) both better than 0.96. We also discovered a less accurate correlation between the barrier height and HOMO energy. These results reconfirm the validity and effectiveness of employing the Hirshfeld charge as a reliable descriptor of both reactivity and regioselectivity for this vastly important category of chemical transformations.

Applications of organocatalytic asymmetric synthesis to drug prototypes--dual action and selective inhibitors of n-nitric oxide synthase with activity against the 5-HT1D/1B subreceptors.

PubMed

Hanessian, Stephen; Stoffman, Eli; Mi, Xueling; Renton, Paul

2011-03-04

The scope of MacMillan's organocatalytic asymmetric conjugate addition reaction of indoles and electron-rich aromatics to α,β-unsaturated aldehydes has been extended to the use of 3-amino crotonaldehydes as substrates. The aromatics used include indoles as well as an aniline and a furan. The scope and effect of the groups on nitrogen (R, R') has also been studied. The method has been applied to the concise synthesis of an advanced precursor to S-(+)-1, a drug prototype for the treatment of migraine headaches.

Chemistry and properties of new poly(arylene ether imidazoles)

NASA Technical Reports Server (NTRS)

Connell, J. W.; Hergenrother, P. M.

1990-01-01

As part of a program to develop high-temperature high-performance structural resins for aerospace applications, the chemistry and properties of new poly(arylene ether imidazoles) were investigated. The polymers were prepared by the nucleophilic displacement reaction of aromatic bis(imidazolephenols) with activated aromatic difluoro compounds. The amorphous thermoplastic polymers exhibited glass transition temperatures from 230 to 301 C, inherent viscosities from 0.46 to 1.46 dL/g, and number-average molecular weights as high as 59,300 g/mole. The polymers exhibit good toughness, adhesive, composite, and film properties. The chemical, physical, and mechanical properties of these materials are discussed.

The synthesis of benzimidazoles and quinoxalines from aromatic diamines and alcohols by iridium-catalyzed acceptorless dehydrogenative alkylation.

PubMed

Hille, Toni; Irrgang, Torsten; Kempe, Rhett

2014-05-05

Benzimidazoles and quinoxalines are important N-heteroaromatics with many applications in pharmaceutical and chemical industry. Here, the synthesis of both classes of compounds starting from aromatic diamines and alcohols (benzimidazoles) or diols (quinoxalines) is reported. The reactions proceed through acceptorless dehydrogenative condensation steps. Water and two equivalents of hydrogen are liberated in the course of the reactions. An Ir complex stabilized by the tridentate P^N^P ligand N(2) ,N(6) -bis(di-isopropylphosphino)pyridine-2,6-diamine revealed the highest catalytic activity for both reactions. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

[Preparation and antimicrobial effect of aromatic, natural and bacteriostatic foot wash with skin care].

PubMed

Gao, Su-Hua; Zhao, Guo-Xiang; Yang, Xiao-Dong; Xu, Ling-Ling

2013-06-01

To prepare the aromatic, natural and bacteriostatic foot wash with skin care and research the inhibition effect on the different bacteria and pathogenic fungus which cause dermatophytosis. It was prepared by using Sophoraflavescens and Dictamnus dasycarpus as materials with the addition of Aloe extract, essential oil, surfactant, etc. The antifungal and antibacterial activity was researched by the levitation liquid quantitative method. The foot wash smelled faintly scent. The use of this product can produce a rich foam. The inhibitory rate were all more than 90%. The preparation process of the foot wash was simple. It has obviously bacteriostatic and fungistatic effect.

Spices as functional foods.

PubMed

Viuda-Martos, M; Ruiz-Navajas, Y; Fernández-López, J; Pérez-Alvarez, J A

2011-01-01

Spices and aromatic herbs have been used since antiquity as preservatives, colorants, and flavor enhancers. Spices, which have long been the basis of traditional medicine in many countries, have also been the subject of study, particularly by the chemical, pharmaceutical, and food industries, because of their potential use for improving health. Both in vitro and in vivo studies have demonstrated how these substances act as antioxidants, digestive stimulants, and hypolipidemics and show antibacterial, anti-inflammatory, antiviral, and anticancerigenic activities. These beneficial physiological effects may also have possible preventative applications in a variety of pathologies. The aim of this review is to present an overview of the potential of spices and aromatic herbs as functional foods.

Transport properties of nonelectrolyte liquid mixtures—VI. Viscosimetric study of binary mixtures of hexafluorobenzene with aromatic hydrocarbons

NASA Astrophysics Data System (ADS)

Dymond, J. H.; Robertson, J.

1985-01-01

Viscosity coefficients for binary mixtures of hexafluorobenzene with benzene, toluene, para-xylene, and mesitylene have been measured along the saturation line at temperatures from 15 to 120°C using specially designed capillary viscometers. Densities were measured using a pyknometer and volume-change apparatus. Deviations of the viscosities from a rectilinear dependence on mole fraction are consistent with enhanced interactions between unlike species, which increase with increasing number of methyl groups on the aromatic hydrocarbon and decrease with increasing temperature. The application of the Grunberg and Nissan equation, the Hildebrand equation, and energy of activation theories to these results is examined.

NNP-Type Pincer Imidazolylphosphine Ruthenium Complexes: Efficient Base-Free Hydrogenation of Aromatic and Aliphatic Nitriles under Mild Conditions.

PubMed

Adam, Rosa; Alberico, Elisabetta; Baumann, Wolfgang; Drexler, Hans-Joachim; Jackstell, Ralf; Junge, Henrik; Beller, Matthias

2016-03-24

A series of seven novel N(Im)N(H)P-type pincer imidazolylphosphine ruthenium complexes has been synthesized and fully characterized. The use of hydrogenation of benzonitrile as a benchmark test identified [RuHCl(CO)(N(Im)N(H) P(tBu))] as the most active catalyst. With its stable Ru-BH4 analogue, in which chloride is replaced by BH4, a broad range of (hetero)aromatic and aliphatic nitriles, including industrially interesting adiponitrile, has been hydrogenated under mild and base-free conditions. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

4-Aminobiphenyl Downregulation of NAT2 Acetylator Genotype–Dependent N- and O-acetylation of Aromatic and Heterocyclic Amine Carcinogens in Primary Mammary Epithelial Cell Cultures from Rapid and Slow Acetylator Rats

PubMed Central

Jefferson, Felicia A.; Xiao, Gong H.; Hein, David W.

2009-01-01

Aromatic and heterocyclic amine carcinogens present in the diet and in cigarette smoke induce breast tumors in rats. N-acetyltransferase 1 (NAT1) and N-acetyltransferase 2 (NAT2) enzymes have important roles in their metabolic activation and deactivation. Human epidemiological studies suggest that genetic polymorphisms in NAT1 and/or NAT2 modify breast cancer risk in women exposed to these carcinogens. p-Aminobenzoic acid (selective for rat NAT2) and sulfamethazine (SMZ; selective for rat NAT1) N-acetyltransferase catalytic activities were both expressed in primary cultures of rat mammary epithelial cells. PABA, 2-aminofluorene, and 4-aminobiphenyl N-acetyltransferase and N-hydroxy-2-amino-1-methyl-6-phenylimidazo[4,5-b] pyridine and N-hydroxy-2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline O-acetyltransferase activities were two- to threefold higher in mammary epithelial cell cultures from rapid than slow acetylator rats. In contrast, SMZ (a rat NAT1-selective substrate) N-acetyltransferase activity did not differ between rapid and slow acetylators. Rat mammary cells cultured in the medium supplemented 24 h with 10μM ABP showed downregulation in the N-and O-acetylation of all substrates tested except for the NAT1-selective substrate SMZ. This downregulation was comparable in rapid and slow NAT2 acetylators. These studies clearly show NAT2 acetylator genotype–dependent N- and O-acetylation of aromatic and heterocyclic amine carcinogens in rat mammary epithelial cell cultures to be subject to downregulation by the arylamine carcinogen ABP. PMID:18842621

Aromatic D-amino acids act as chemoattractant factors for human leukocytes through a G protein-coupled receptor, GPR109B.

PubMed

Irukayama-Tomobe, Yoko; Tanaka, Hirokazu; Yokomizo, Takehiko; Hashidate-Yoshida, Tomomi; Yanagisawa, Masashi; Sakurai, Takeshi

2009-03-10

GPR109B (HM74) is a putative G protein-coupled receptor (GPCR) whose cognate ligands have yet to be characterized. GPR109B shows a high degree of sequence similarity to GPR109A, another GPCR that was identified as a high-affinity nicotinic acid (niacin) receptor. However, the affinity of nicotinic acid to GPR109B is very low. In this study, we found that certain aromatic D-amino acids, including D-phenylalanine, D-tryptophan, and the metabolite of the latter, D-kynurenine, decreased the activity of adenylate cyclase in cells transfected with GPR109B cDNA through activation of pertussis toxin (PTX)-sensitive G proteins. These D-amino acids also elicited a transient rise of intracellular Ca(2+) level in cells expressing GPR109B in a PTX-sensitive manner. In contrast, these D-amino acids did not show any effects on cells expressing GPR109A. We found that the GPR109B mRNA is abundantly expressed in human neutrophils. D-phenylalanine and D-tryptophan induced a transient increase of intracellular Ca(2+) level and a reduction of cAMP levels in human neutrophils. Furthermore, knockdown of GPR109B by RNA interference inhibited the D-amino acids-induced decrease of cellular cAMP levels in human neutrophils. These D-amino acids induced chemotactic activity of freshly prepared human neutrophils. We also found that D-phenylalanine and D-tryptophan induced chemotactic responses in Jurkat cells transfected with the GPR109B cDNA but not in mock-transfected Jurkat cells. These results suggest that these aromatic D-amino acids elicit a chemotactic response in human neutrophils via activation of GPR109B.

Ring flips revisited: (13)C relaxation dispersion measurements of aromatic side chain dynamics and activation barriers in basic pancreatic trypsin inhibitor.

PubMed

Weininger, Ulrich; Modig, Kristofer; Akke, Mikael

2014-07-22

Intramolecular motions of proteins are critical for biological function. Transient structural fluctuations underlie a wide range of processes, including enzyme catalysis, ligand binding to buried sites, and generic protein motions, such as 180° rotation of aromatic side chains in the protein interior, but remain poorly understood. Understanding the dynamics and molecular nature of concerted motions requires characterization of their rates and energy barriers. Here we use recently developed (13)C transverse relaxation dispersion methods to improve our current understanding of aromatic ring flips in basic pancreatic trypsin inhibitor (BPTI). We validate these methods by benchmarking ring-flip rates against the three previously characterized cases in BPTI, namely, Y23, Y35, and F45. Further, we measure conformational exchange for one additional aromatic ring, F22, which can be interpreted in terms of a flip rate of 666 s(-1) at 5 °C. Upon inclusion of our previously reported result that Y21 also flips slowly [Weininger, U., et al. (2013) J. Phys. Chem. B 117, 9241-9247], the (13)C relaxation dispersion experiments thus reveal relatively slow ring-flip rates for five of eight aromatic residues in BPTI. These results are in contrast with previous reports, which have estimated that all rings, except Y23, Y35, and F45, flip with a high rate at ambient temperature. The (13)C relaxation dispersion data result in an updated rank order of ring-flip rates in BPTI, which agrees considerably better with that estimated from a recent 1 ms molecular dynamics trajectory than do previously published NMR data. However, significant quantitative differences remain between experiment and simulation, in that the latter yields flip rates that are in many cases too fast by 1-2 orders of magnitude. By measuring flip rates across a temperature range of 5-65 °C, we determined the activation barriers of ring flips for Y23, Y35, and F45. Y23 and F45 have identical activation parameters, suggesting that the fluctuations of the protein core around these residues are similar in character. Y35 differs from the other two in its apparent activation entropy. These results might be rationalized by the fact that Y23 and F45 are located in the same region of the structure while Y35 is remote from the other two rings. As indicated by our new results for the exceptionally well-characterized protein BPTI, (13)C relaxation dispersion experiments open the possibility of studying ring flips in a range of cases wider than that previously possible.

Structure-activity relationship studies on a Trp dendrimer with dual activities against HIV and enterovirus A71. Modifications on the amino acid.

PubMed

Martínez-Gualda, Belén; Sun, Liang; Rivero-Buceta, Eva; Flores, Aida; Quesada, Ernesto; Balzarini, Jan; Noppen, Sam; Liekens, Sandra; Schols, Dominique; Neyts, Johan; Leyssen, Pieter; Mirabelli, Carmen; Camarasa, María-José; San-Félix, Ana

2017-03-01

We have recently described a new class of dendrimers with tryptophan (Trp) on the surface that show dual antiviral activities against HIV and EV71 enterovirus. The prototype compound of this family is a pentaerythritol derivative with 12 Trps on the periphery. Here we complete the structure-activity relationship studies of this family to identify key features that might be significant for the antiviral activity. With this aim, novel dendrimers containing different amino acids (aromatic and non-aromatic), tryptamine (a "decarboxylated" analogue of Trp) and N-methyl Trp on the periphery have been prepared. Dendrimer with N-Methyl Trp was the most active against HIV-1 and HIV-2 while dendrimer with tyrosine was endowed with the most potent antiviral activity against EV71. This tyrosine dendrimer proved to inhibit a large panel of EV71 clinical isolates (belonging to different clusters) in the low nanomolar/high picomolar range. In addition, a new synthetic procedure (convergent approach) has been developed for the synthesis of the prototype and some other dendrimers. This convergent approach proved more efficient (higher yields, easier purification) than the divergent approach previously reported. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

Discovery of Peptidomimetic Ligands of EED as Allosteric Inhibitors of PRC2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barnash, Kimberly D.; The, Juliana; Norris-Drouin, Jacqueline L.

The function of EED within polycomb repressive complex 2 (PRC2) is mediated by a complex network of protein–protein interactions. Allosteric activation of PRC2 by binding of methylated proteins to the embryonic ectoderm development (EED) aromatic cage is essential for full catalytic activity, but details of this regulation are not fully understood. EED’s recognition of the product of PRC2 activity, histone H3 lysine 27 trimethylation (H3K27me3), stimulates PRC2 methyltransferase activity at adjacent nucleosomes leading to H3K27me3 propagation and, ultimately, gene repression. By coupling combinatorial chemistry and structure-based design, we optimized a low-affinity methylated jumonji, AT-rich interactive domain 2 (Jarid2) peptide tomore » a smaller, more potent peptidomimetic ligand (K d = 1.14 ± 0.14 μM) of the aromatic cage of EED. Our strategy illustrates the effectiveness of applying combinatorial chemistry to achieve both ligand potency and property optimization. Furthermore, the resulting ligands, UNC5114 and UNC5115, demonstrate that targeted disruption of EED’s reader function can lead to allosteric inhibition of PRC2 catalytic activity.« less

Redox shuttles having an aromatic ring fused to a 1,1,4,4-tetrasubstituted cyclohexane ring

DOEpatents

Weng, Wei; Zhang, Zhengcheng; Amine, Khalil

2015-12-01

An electrolyte includes an alkali metal salt; an aprotic solvent; and a redox shuttle additive including an aromatic compound having at least one aromatic ring fused with at least one non-aromatic ring, the aromatic ring having two or more oxygen or phosphorus-containing substituents.

Compactness Aromaticity of Atoms in Molecules

PubMed Central

Putz, Mihai V.

2010-01-01

A new aromaticity definition is advanced as the compactness formulation through the ratio between atoms-in-molecule and orbital molecular facets of the same chemical reactivity property around the pre- and post-bonding stabilization limit, respectively. Geometrical reactivity index of polarizability was assumed as providing the benchmark aromaticity scale, since due to its observable character; with this occasion new Hydrogenic polarizability quantum formula that recovers the exact value of 4.5 a03 for Hydrogen is provided, where a0 is the Bohr radius; a polarizability based–aromaticity scale enables the introduction of five referential aromatic rules (Aroma 1 to 5 Rules). With the help of these aromatic rules, the aromaticity scales based on energetic reactivity indices of electronegativity and chemical hardness were computed and analyzed within the major semi-empirical and ab initio quantum chemical methods. Results show that chemical hardness based-aromaticity is in better agreement with polarizability based-aromaticity than the electronegativity-based aromaticity scale, while the most favorable computational environment appears to be the quantum semi-empirical for the first and quantum ab initio for the last of them, respectively. PMID:20480020

40 CFR 721.7200 - Perfluoroalkyl aromatic carbamate modified alkyl methacrylate copolymer.

Code of Federal Regulations, 2010 CFR

2010-07-01

... for cancer; 1.0 percent for other effects), (f), (g)(1)(ii), (g)(2)(ii), and (g)(5). In addition, the... substance may cause lung effects. (ii) Industrial, commercial, and consumer activities. Requirements as...

40 CFR 721.7200 - Perfluoroalkyl aromatic carbamate modified alkyl methacrylate copolymer.

Code of Federal Regulations, 2013 CFR

2013-07-01

... for cancer; 1.0 percent for other effects), (f), (g)(1)(ii), (g)(2)(ii), and (g)(5). In addition, the... substance may cause lung effects. (ii) Industrial, commercial, and consumer activities. Requirements as...

40 CFR 721.7200 - Perfluoroalkyl aromatic carbamate modified alkyl methacrylate copolymer.

Code of Federal Regulations, 2012 CFR

2012-07-01

... for cancer; 1.0 percent for other effects), (f), (g)(1)(ii), (g)(2)(ii), and (g)(5). In addition, the... substance may cause lung effects. (ii) Industrial, commercial, and consumer activities. Requirements as...

40 CFR 721.7200 - Perfluoroalkyl aromatic carbamate modified alkyl methacrylate copolymer.

Code of Federal Regulations, 2014 CFR

2014-07-01

... for cancer; 1.0 percent for other effects), (f), (g)(1)(ii), (g)(2)(ii), and (g)(5). In addition, the... substance may cause lung effects. (ii) Industrial, commercial, and consumer activities. Requirements as...

40 CFR 721.7200 - Perfluoroalkyl aromatic carbamate modified alkyl methacrylate copolymer.

Code of Federal Regulations, 2011 CFR

2011-07-01

... for cancer; 1.0 percent for other effects), (f), (g)(1)(ii), (g)(2)(ii), and (g)(5). In addition, the... substance may cause lung effects. (ii) Industrial, commercial, and consumer activities. Requirements as...

Chemistry Notes.

ERIC Educational Resources Information Center

School Science Review, 1983

1983-01-01

Presents chemistry experiments, laboratory procedures, demonstrations, and classroom materials/activities. These include: experiments on colloids, processing of uranium ore, action of heat on carbonates; color test for phenols and aromatic amines; solvent properties of non-electrolytes; stereoscopic applications/methods; a valency balance;…

ACTIVATION OF OYSTER DEFENSES BY ENVIRONMENTAL CONTAMINANTS

EPA Science Inventory

Four field studies performed on eastern oysters Crassostrea virginica support a hypothesis that Cu, Zn, and perhaps butyltins and polycyclic aromatic hydrocarbons (PAH) can stimulate hemopoiesis, hemocyte locomotion and hemocyte bactericidal capacity. The first study found circul...

Antioxidant activity of a new aromatic geranyl derivative of the resinous exudates from Heliotropium glutinosum Phil.

PubMed

Modak, Brenda; Rojas, Macarena; Torres, René; Rodilla, Jesús; Luebert, Federico

2007-05-21

Heliotropium glutinosum Phil. (Heliotropiceae) is a resinous bush that grows at a height of 2000 m in Chañaral, Chile. From the resinous exudates of Heliotropium glutinosum Phil. a new aromatic geranyl derivative: 4-methoxy-3-[(2)-7'-methyl-3'-hydroxymethyl-2',6'-octadienyl] phenol (1) and three flavonoids: 5,3'-dihydroxy-7,4'-dimethoxyflavanone (2), 5,4'-dihydroxy-7-methoxyflavanone (3) and 4'-acetyl-5-hydroxy-7-methoxyflavanone (4) were isolated and their structures were determined. Their antioxidant activity were evaluated using the bleaching of ABTS and DPPH derived cation radical methods and expressed in terms of FRE (fast reacting equivalents) and TRE (total reacting equivalents), where FRE is a good measure of the quick protection of a given compound against oxidants and TRE measures the degree of long-term protection of the antioxidant, or how effective it is against a strong oxidative stress.

Indole-3-acetic acid biosynthetic pathway and aromatic amino acid aminotransferase activities in Pantoea dispersa strain GPK.

PubMed

Kulkarni, G B; Nayak, A S; Sajjan, S S; Oblesha, A; Karegoudar, T B

2013-05-01

This investigation deals with the production of IAA by a bacterial isolate Pantoea dispersa strain GPK (PDG) identified by 16S rRNA gene sequence analysis. HPLC and Mass spectral analysis of metabolites from bacterial spent medium revealed that, IAA production by PDG is Trp-dependent and follows indole-3-pyruvic acid (IPyA) pathway. Substrate specificity study of aromatic amino acid aminotransferase (AAT) showed high activities, only when tryptophan (Trp) and α-ketoglutarate (α-kg) were used as substrates. AAT is highly specific for Trp and α-kg as amino group donor and acceptor, respectively. The effect of exogenous IAA on bacterial growth was established. Low concentration of exogenous IAA induced the growth, whereas high concentration decreased the growth of bacterium. PDG treatment significantly increased the root length, shoot length and dry mass of the chickpea and pigeon pea plants. © 2013 The Society for Applied Microbiology.

Dearomative dihydroxylation with arenophiles

NASA Astrophysics Data System (ADS)

Southgate, Emma H.; Pospech, Jola; Fu, Junkai; Holycross, Daniel R.; Sarlah, David

2016-10-01

Aromatic hydrocarbons are some of the most elementary feedstock chemicals, produced annually on a million metric ton scale, and are used in the production of polymers, paints, agrochemicals and pharmaceuticals. Dearomatization reactions convert simple, readily available arenes into more complex molecules with broader potential utility, however, despite substantial progress and achievements in this field, there are relatively few methods for the dearomatization of simple arenes that also selectively introduce functionality. Here we describe a new dearomatization process that involves visible-light activation of small heteroatom-containing organic molecules—arenophiles—that results in their para-cycloaddition with a variety of aromatic compounds. The approach uses N-N-arenophiles to enable dearomative dihydroxylation and diaminodihydroxylation of simple arenes. This strategy provides direct and selective access to highly functionalized cyclohexenes and cyclohexadienes and is orthogonal to existing chemical and biological dearomatization processes. Finally, we demonstrate the synthetic utility of this strategy with the concise synthesis of several biologically active compounds and natural products.

Substituent Effects on Desferrithiocin and Desferrithiocin Analogue Iron Clearing and Toxicity Profiles

PubMed Central

Bergeron, Raymond J.; Wiegand, Jan; Bharti, Neelam; McManis, James S.

2012-01-01

Desferrithiocin (DFT, 1) is a very efficient iron chelator when given orally. However, it is severely nephrotoxic. Structure-activity studies with 1 demonstrated that removal of the aromatic nitrogen to provide desazadesferrithiocin (DADFT, 2) and introduction of either a hydroxyl group or a polyether fragment onto the aromatic ring resulted in orally active iron chelators that were much less toxic than 1. The purpose of the current study was to determine if a comparable reduction in renal toxicity could be achieved by performing the same structural manipulations on 1 itself. Accordingly, three DFT analogues were synthesized. Iron clearing efficiency and ferrokinetics were evaluated in rats and primates; toxicity assessments were carried out in rodents. The resulting DFT ligands demonstrated a reduction in toxicity that was equivalent to that of the DADFT analogues and presented with excellent iron clearing properties. PMID:22889170

Atypical kinetic behavior of chloroperoxidase-mediated oxidative halogenation of polycyclic aromatic hydrocarbons.

PubMed

Aburto, Jorge; Correa-Basurto, Jose; Torres, Eduardo

2008-12-01

We have identified an atypical kinetic behavior for the oxidative halogenation of several polycyclic aromatic hydrocarbons (PAHs) by chloroperoxidase (CPO) from Caldariomyces fumago. This behavior resembles the capacity of some members of the P450 family to simultaneously recognize several substrate molecules at their active sites. Indeed, fluorometric studies showed that PAHs exist in solution as monomers and pi-pi dimers that interact to different extents with CPO. The dissociation constants of dimerization were evaluated for every single PAH by spectrofluorometry. Furthermore, docking studies also suggest that CPO might recognize either one or two substrate molecules in its active site. The atypical sigmoidal kinetic behavior of CPO in the oxidative halogenation of PAHs is explained in terms of different kinetic models for non-heteroatomic PAHs (naphthalene, anthracene and pyrene). The results suggest that the actual substrate for CPO in this study was the pi-pi dimer for all evaluated PAHs.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gianetto, A.; Farag, H.I.; Blasetti, A.P.

Changes of the relative importance of intradiffusion on USY zeolite crystals were studied as a way of affecting selectivity of catalytic cracking reactions. Zeolite crystals were synthesized (Si/Al = 2.4), activated and stabilized using ion exchange and steam calcination to obtain USSY (Ultra Stable Submicron Y) zeolites. After the activation the zeolites were pelletized (45--60 [mu]m particles). USSYs were tested in a novel Riser Simulator. Results obtained show that total aromatics (BTX), benzene, C[sub 4] olefins, and coke were significantly affected with the change of zeolite crystal sizes. Gasolines produced with USSY zeolites contain less aromatics and particularly lower benzenemore » levels. Experimental results were analyzed with a model including several lumps: unconverted gas oil, gasoline, light gases, and coke. This model also accounts for catalyst deactivation as a function of coke on catalyst. Various kinetic parameters were determined with their corresponding spans for the 95% level of confidence.« less

Gas-particle distributions, sources and health effects of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and polychlorinated naphthalenes (PCNs) in Venice aerosols.

PubMed

Gregoris, Elena; Argiriadis, Elena; Vecchiato, Marco; Zambon, Stefano; De Pieri, Silvia; Donateo, Antonio; Contini, Daniele; Piazza, Rossano; Barbante, Carlo; Gambaro, Andrea

2014-04-01

Air samples were collected in Venice during summer 2009 and 2012 to measure gas and particulate concentrations of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and polychlorinated naphthalenes (PCNs). PCB-11, considered a marker for non-Aroclor contamination of the environment, was found for the first time in the Venetian lagoon and in Europe. An investigation on sources has been conducted, evidencing traffic as the major source of PAHs, whereas PCBs have a similar composition to Aroclor 1248 and 1254; in 2009 a release of PCN-42 has been hypothesized. Toxicological evaluation by TCA and TEQ methods, conducted for the first time in Venice air samples, identified BaP, PCB-126 and PCB-169 as the most important contributors to the total carcinogenic activity of PAHs and the total dioxin-like activity of PCBs and PCNs. Copyright © 2014 Elsevier B.V. All rights reserved.

Polynuclear aromatic hydrocarbons for fullerene synthesis in flames

DOEpatents

Alford, J. Michael; Diener, Michael D.

2006-12-19

This invention provides improved methods for combustion synthesis of carbon nanomaterials, including fullerenes, employing multiple-ring aromatic hydrocarbon fuels selected for high carbon conversion to extractable fullerenes. The multiple-ring aromatic hydrocarbon fuels include those that contain polynuclear aromatic hydrocarbons. More specifically, multiple-ring aromatic hydrocarbon fuels contain a substantial amount of indene, methylnapthalenes or mixtures thereof. Coal tar and petroleum distillate fractions provide low cost hydrocarbon fuels containing polynuclear aromatic hydrocarbons, including without limitation, indene, methylnapthalenes or mixtures thereof.

Cytotoxicity and cellular response mechanisms of water-soluble platinum(II) complexes of lidocaine and phenylcyanamide derivatives.

PubMed

Tabrizi, Leila; Chiniforoshan, Hossein

2017-02-01

Three new platinum(II) complexes of lidocaine and phenylcyanamide derivative ligands of formula K[Pt(3,5-(NO 2 ) 2 pcyd) 2 (LC)], 1, K[Pt(3,5-(CF 3 ) 2 pcyd) 2 (LC)], 2, K[Pt(3,5-Cl 2 pcyd) 2 (LC)], 3 (LC: lidocaine, 3,5-(NO 2 ) 2 pcyd: 3,5-dinitro phenylcyanamide, 3,5-(CF 3 ) 2 pcyd: 3,5-bis(trifluoromethyl) phenylcyanamide, 3,5-Cl 2 pcyd: 3,5-dichloro phenylcyanamide) have been synthesized and fully characterized. Cellular uptake, DNA platination and cytotoxicity against a panel of human tumor cell lines were evaluated. The complexes 1-3 revealed a significant in vitro antiproliferative activity against human ovarian carcinoma (A2780), colorectal adenocarcinoma (HT29), breast (MCF-7), liver hepatocellular carcinoma (HepG-2) and lung adenocarcinoma (A549) cancer cell lines. All the complexes are more active than cisplatin and follow the trend 1 > 2 > 3. Mechanistic studies showed that the trend in cytotoxicity of the Pt(II) complexes is mainly consistent with their ability to accumulate into cancer cells and to increase intracellular basal reactive oxygen species levels, which consequently results in the loss of mitochondrial membrane potential and apoptosis induction. The complex 1 caused to approximately 80-fold higher DNA platination level with respect to cisplatin. The complexes 1-3 can considerably stimulate the production of hydrogen peroxide in a time-dependent manner. Also, the complexes 1-3 induced an increase in reactive oxygen species (ROS) production that was superior to that induced by antimycin. The complex 1 had the most effect on ROS production in comparison with other complexes.

Effects of pectin-containing diets on the hepatic macromolecular covalent binding of 2,6-dinitro-(/sup 3/H)toluene in Fischer-344 rats

DOE Office of Scientific and Technical Information (OSTI.GOV)

deBethizy, J.D.; Sherrill, J.M.; Rickert, D.E.

1983-07-01

The influence of diets varying in pectin content on intestinal microfloral metabolic capacity of rats has been investigated as a possible mechanism for the alteration of toxicity of 2,6-dinitrotoluene (2,6-DNT) produced by these diets. Male F-344 rats were fed a purified diet (AIN-76A), AIN-76A plus 5% or 10% citrus pectin, or either of two cereal-based diets that vary in pectin content, NIH-07 or Purina Chow 5002. After 28 days, rats were given tritium-labeled 2,6-DNT (10 or 75 mg/kg po) and killed 12 hr later. Total hepatic macromolecular covalent binding (CVB) was determined by exhaustive extraction. The CVB of 2,6-DNT wasmore » found to be independent of diet at 10 mg/kg. However, at 75 mg/kg CVB was increased 40% by feeding 5% pectin in the purified diet and 90% by feeding 10% pectin in the purified diet. Animals fed Purina 5002 and NIH-07 had 135 and 150% higher CVB, respectively, than animals fed the purified diet alone and significantly greater CVB than animals fed the pectin supplemented diets. Elevated (two- to threefold) beta-glucuronidase and nitroreductase activities, microfloral enzymes proposed to be involved in the activation of 2,6-DNT to a toxicant, were found in the cecal contents of animals fed the pectin-containing diets which correlated with a two- to threefold increase in total number of cecal anaerobes. These results suggest that pectin-induced changes in microflora may enhance hepatoxicity after high doses of 2,6-DNT.« less

[Analysis of aromatic hydrocarbons in cracking products of jet fuel by comprehensive two-dimensional gas chromatography-mass spectrometry].

PubMed

Li, Haijing; Zhang, Xiangwen

2017-08-08

As coking precursors, aromatic hydrocarbons have an effect on the cracking stability of fuels. A method for identifying and quantitating aromatics in the supercritical cracking products of jet fuel was established by comprehensive two-dimensional gas chromatography coupled with mass spectrometry (GC×GC-MS). The effects of main chromatographic conditions such as initial oven temperature and modulation period on the separation of supercritical cracking products were studied. The method has good separation ability for polycyclic aromatic hydrocarbons (PAH) isomers. A total of 27 aromatics, including monocyclic aromatic hydrocarbons, bicyclic aromatic hydrocarbons, tricyclic aromatic hydrocarbons, tetracyclic aromatic hydrocarbons, etc., were identified based on standard mass spectra, the retention times of standards and literature reports. Moreover, the corresponding quantitative determination was achieved by external standard method of GC×GC-FID. The results showed that the contents of aromatics increased with the increase of gas yield. When gas yield reached 22%, the bicyclic aromatic hydrocarbons began to produce, and their contents increased exponentially with the increase of gas yield. Compared with the traditional GC-MS, the method has better separation and qualitative ability, and can be applied to the separation of complex samples and qualitative and quantitative analyses of cracking products.

Removal of Aromatic Pollutant Surrogate from Water by Recyclable Magnetite-Activated Carbon Nanocomposite: An Experiment for General Chemistry

ERIC Educational Resources Information Center

Furlan, Ping Y.; Melcer, Michael E.

2014-01-01

A general chemistry laboratory experiment using readily available chemicals is described to introduce college students to an exciting class of nanocomposite materials. In a one-step room temperature synthetic process, magnetite nanoparticles are embedded onto activated carbon matrix. The resultant nanocomposite has been shown to combine the…

MORPHOLOGICAL TRANSFORMATION OF C3H10T1/2CL8 CELLS BY CYCLOPENTA-FUSED DERIVATIVES OF BENZO[A]PYRENE AND BENZO[E]PYRENE

EPA Science Inventory

Cyclopenta-fused homologs of polycyclic aromatic hydrocarbons (PAH) have proven to be more genotoxic and tumorigenic than their parent PAHs. In an effort to uncover their mechanisms of metabolic activation, the morphological transforming activities of dibenzo[k,mno]acephenanthryl...

Chemical composition and biological activity of essential oils from wild growing aromatic plant species of Skimmia laureola and Juniperus macropoda from Western Himalaya

USDA-ARS?s Scientific Manuscript database

The Himalayan region is very rich in a great variety of medicinal plants. In this investigation the essential oils of two selected species are described for their antimicrobial and larvicidal as well as biting deterrent activities. Additionally, the odors are characterized. Analyzed by simultaneous ...

40 CFR Table 6 to Subpart Vvvv of... - Default Organic HAP Contents of Petroleum Solvent Groups

Code of Federal Regulations, 2010 CFR

2010-07-01

... Spirits 150 EC, Naphtha, Mixed Hydrocarbon, Aliphatic Hydrocarbon, Aliphatic Naptha, Naphthol Spirits... Aromatic Naphtha, Light Aromatic Hydrocarbons, Aromatic Hydrocarbons, Light Aromatic Solvent.) 6 4% Xylene...

Non-ovarian aromatization is required to activate female sexual motivation in testosterone-treated ovariectomized quail

PubMed Central

de Bournonville, Catherine; Balthazart, Jacques; Ball, Gregory F.; Cornil, Charlotte A.

2016-01-01

Although aromatase is expressed in both male and female brains, its functional significance in females remains poorly understood. In female quail, sexual receptivity is activated by estrogens. However it is not known whether sexual motivation is similarly estrogen-dependent and whether estrogens locally produced in the brain contribute to these behavioral responses. Four main experiments were designed to address these questions. In experiment 1 chronic treatment of females with the anti-estrogen tamoxifen decreased their receptivity, confirming that this response is under the control of estrogens. In experiment 2 chronic treatment with tamoxifen significantly decreased sexual motivation as treated females no longer approached a sexual partner. In experiment 3 (a) ovariectomy (OVX) induced a significant decrease of time spent near the male and a significantly decreased receptivity compared to gonadally intact females, (b) treatment with testosterone (OVX+T) partially restored these responses and (c) this effect of T was prevented when estradiol synthesis was inhibited by the potent aromatase inhibitor Vorozole (OVX+T+VOR). Serum estradiol concentration was significantly higher in OVX+T than in OVX or OVX+T+VOR females. Together these data demonstrate that treatment of OVX females with T increases sexual motivation and that these effects are mediated at least in part by non-gonadal aromatization of the androgen. Finally, assays of aromatase activity on brain and peripheral tissues (Experiment 4) strongly suggest that brain aromatization contributes to behavioral effects observed here following T treatment but alternative sources of estrogens (e.g. liver) should also be considered. PMID:27189762

Highly conformationally constrained halogenated 6-spiroepoxypenicillins as probes for the bioactive side-chain conformation of benzylpenicillin

NASA Astrophysics Data System (ADS)

Shute, Richard E.; Jackson, David E.; Bycroft, Barrie W.

1989-06-01

The halogenated 6-spiroepoxypenicillins are a series of novel semisynthetic β-lactam compounds with highly conformationally restricted side chains incorporating an epoxide. Their biological activity profiles depend crucially on the configuration at position C-3 of that epoxide. In derivatives with aromatic-containing side chains, e.g., anilide, the 3 R-compounds possess notable Gram-positive antibacterial activity and potent β-lactamase inhibitory properties. The comparable 3S-compounds are antibacterially inactive, but retain β-lactamase inhibitory activity. Using the molecular simulation programs COSMIC and ASTRAL, we attempted to map a putative, lipophilic accessory binding site on the PBPs that must interact with the side-chain aromatic residue. Comparative computer-assisted modelling of the 3 R, and 3 S-anilides, along with benzylpenicillin, indicated that the available conformational space at room temperature for the side chains of the 3 R and the 3 S-anilides was mutually exclusive. The conformational space for the more flexible benzylpenicillin could accommodate the side chains of both the constrained penicillin derivatives. By a combination of van der Waals surface calculations and a pharmacophoric distance approach, closely coincident conformers of the 3 R-anilide and benzylpenicillin were identified. These conformers must be related to the antibacterial, `bioactive' conformer for the classical β-lactam antibiotics. From these proposed bioactive conformations, a model for the binding of benzylpenicillin to the PBPs relating the three-dimensional arrangement of a putative lipophilic S2-subsite, specific for the side-chain aromatic moiety, and the 3 α-carboxylate functionality is presented.

The effect of geometrical presentation of multimodal cation-exchange ligands on selective recognition of hydrophobic regions on protein surfaces.

PubMed

Woo, James; Parimal, Siddharth; Brown, Matthew R; Heden, Ryan; Cramer, Steven M

2015-09-18

The effects of spatial organization of hydrophobic and charged moieties on multimodal (MM) cation-exchange ligands were examined by studying protein retention behavior on two commercial chromatographic media, Capto™ MMC and Nuvia™ cPrime™. Proteins with extended regions of surface-exposed aliphatic residues were found to have enhanced retention on the Capto MMC system as compared to the Nuvia cPrime resin. The results further indicated that while the Nuvia cPrime ligand had a strong preference for interactions with aromatic groups, the Capto MMC ligand appeared to interact with both aliphatic and aromatic clusters on the protein surfaces. These observations were formalized into a new set of protein surface property descriptors, which quantified the local distribution of electrostatic and hydrophobic potentials as well as distinguishing between aromatic and aliphatic properties. Using these descriptors, high-performing quantitative structure-activity relationship (QSAR) models (R(2)>0.88) were generated for both the Capto MMC and Nuvia cPrime datasets at pH 5 and pH 6. Descriptors of electrostatic properties were generally common across the four models; however both Capto MMC models included descriptors that quantified regions of aliphatic-based hydrophobicity in addition to aromatic descriptors. Retention was generally reduced by lowering the ligand densities on both MM resins. Notably, elution order was largely unaffected by the change in surface density, but smaller and more aliphatic proteins tended to be more affected by this drop in ligand density. This suggests that modulating the exposure, shape and density of the hydrophobic moieties in multimodal chromatographic systems can alter the preference for surface exposed aliphatic or aromatic residues, thus providing an additional dimension for modulating the selectivity of MM protein separation systems. Copyright © 2015 Elsevier B.V. All rights reserved.

Aromatization of n-hexane by platinum-containing molecular sieves. 2. n-Hexane reactivity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mielczarski, E.; Suk Bong Hong; Davis, M.E.

Pt/KL, Pt/BaKL, Pt/KBaKL, Pt/NaY, Pt/CsNaY, Pt/NaFAU(C), Pt/hex, Pt/SSZ-24, Pt/silica, and Pt/carbon were tested as catalysts for the aromatization of n-hexane at 460-510 C and atmospheric total pressure in order to study the influence of Pt cluster size and support acidity/basicity, microstructure, and chemical composition on activity and selectivity. Analysis of the catalytic and NH{sub 3} temperature-programmed desorption results from Pt/KL, Pt/BaKL, and Pt/KBaKL reveals that the presence of any acidity increases hydrogenolysis at the expense of benzene production. In addition, no increase in aromatization selectivity is observed by the addition of base sites to a Pt/zeolite catalyst, confirming that aromatizationmore » of n-hexane over Pt clusters on nonacidic carriers is monofunctional. High selectivity to benzene over most of the zeolite samples demonstrates that support microstructure does not contribute directly to the aromatization selectivity over Pt catalysts. High selectivity to benzene is observed for a Pt/carbon catalyst suggesting that a zeolitic support is not necessary for good performance. In fact, similar reactivity is obtained from microporous (Pt/SSZ-24) and nonmicroporous (Pt/silica) silica supported platinum catalysts with similar H/Pt values. A clear trend of increasing benzene selectivity with decreasing Pt cluster size is found. These observations suggest that the exceptional reactivity of Pt/KL for the aromatization of n-hexane results from the lack of any acidity in the support and the ability of zeolite L to stabilize the formation of extremely small Pt clusters.« less

Synthesis and accumulation of aromatic aldehydes in an engineered strain of Escherichia coli.

PubMed

Kunjapur, Aditya M; Tarasova, Yekaterina; Prather, Kristala L J

2014-08-20

Aromatic aldehydes are useful in numerous applications, especially as flavors, fragrances, and pharmaceutical precursors. However, microbial synthesis of aldehydes is hindered by rapid, endogenous, and redundant conversion of aldehydes to their corresponding alcohols. We report the construction of an Escherichia coli K-12 MG1655 strain with reduced aromatic aldehyde reduction (RARE) that serves as a platform for aromatic aldehyde biosynthesis. Six genes with reported activity on the model substrate benzaldehyde were rationally targeted for deletion: three genes that encode aldo-keto reductases and three genes that encode alcohol dehydrogenases. Upon expression of a recombinant carboxylic acid reductase in the RARE strain and addition of benzoate during growth, benzaldehyde remained in the culture after 24 h, with less than 12% conversion of benzaldehyde to benzyl alcohol. Although individual overexpression results demonstrated that all six genes could contribute to benzaldehyde reduction in vivo, additional experiments featuring subset deletion strains revealed that two of the gene deletions were dispensable under the conditions tested. The engineered strain was next investigated for the production of vanillin from vanillate and succeeded in preventing formation of the byproduct vanillyl alcohol. A pathway for the biosynthesis of vanillin directly from glucose was introduced and resulted in a 55-fold improvement in vanillin titer when using the RARE strain versus the wild-type strain. Finally, synthesis of the chiral pharmaceutical intermediate L-phenylacetylcarbinol (L-PAC) was demonstrated from benzaldehyde and glucose upon expression of a recombinant mutant pyruvate decarboxylase in the RARE strain. Beyond allowing accumulation of aromatic aldehydes as end products in E. coli, the RARE strain expands the classes of chemicals that can be produced microbially via aldehyde intermediates.

Effects of Olfactory Stimulation from the Fragrance of the Japanese Citrus Fruit Yuzu (Citrus junos Sieb. ex Tanaka) on Mood States and Salivary Chromogranin A as an Endocrinologic Stress Marker

PubMed Central

Asakura, Hiroyuki; Hayashi, Tatsuya

2014-01-01

Abstract Objective: This study investigated the soothing effects of fragrance from yuzu, a Japanese citrus fruit (Citrus junos Sieb. ex Tanaka), with salivary chromogranin A (CgA) used as an endocrinologic stress marker reflecting sympathetic nervous system activity. Methods: Twenty healthy women (mean age, 20.5±0.1 years) participated in a randomized, controlled, crossover study. Participants were examined on two separate occasions—once using the yuzu scent and once using unscented water as a control—in the follicular phase. This experiment measured salivary CgA and the Profile of Mood States (POMS) as a psychological index before and after the aromatic stimulation. Results: Ten-minute inhalation of the yuzu scent significantly decreased salivary CgA. At 30 minutes after the inhalation period, the salivary CgA level further decreased. In addition, POMS revealed that inhalation of the aromatic yuzu oil significantly decreased total mood disturbance, a global measure of affective state, as well as four subscores of emotional symptoms (tension–anxiety, depression–dejection, anger–hostility, and confusion), as long as 30 minutes after the olfactory stimulation. Conclusions: Yuzu's aromatic effects may alleviate negative emotional stress, which, at least in part, would contribute to the suppression of sympathetic nervous system activity. PMID:24742226

Thermostable Alcohol Dehydrogenase from Thermococcus kodakarensis KOD1 for Enantioselective Bioconversion of Aromatic Secondary Alcohols

PubMed Central

Wu, Xi; Zhang, Chong; Orita, Izumi; Imanaka, Tadayuki

2013-01-01

A novel thermostable alcohol dehydrogenase (ADH) showing activity toward aromatic secondary alcohols was identified from the hyperthermophilic archaeon Thermococcus kodakarensis KOD1 (TkADH). The gene, tk0845, which encodes an aldo-keto reductase, was heterologously expressed in Escherichia coli. The enzyme was found to be a monomer with a molecular mass of 31 kDa. It was highly thermostable with an optimal temperature of 90°C and a half-life of 4.5 h at 95°C. The apparent Km values for the cofactors NAD(P)+ and NADPH were similar within a range of 66 to 127 μM. TkADH preferred secondary alcohols and accepted various ketones and aldehydes as substrates. Interestingly, the enzyme could oxidize 1-phenylethanol and its derivatives having substituents at the meta and para positions with high enantioselectivity, yielding the corresponding (R)-alcohols with optical purities of greater than 99.8% enantiomeric excess (ee). TkADH could also reduce 2,2,2-trifluoroacetophenone to (R)-2,2,2-trifluoro-1-phenylethanol with high enantioselectivity (>99.6% ee). Furthermore, the enzyme showed high resistance to organic solvents and was particularly highly active in the presence of H2O–20% 2-propanol and H2O–50% n-hexane or n-octane. This ADH is expected to be a useful tool for the production of aromatic chiral alcohols. PMID:23354700