Nickel-catalyzed synthesis of aryl trifluoromethyl sulfides at room temperature.

PubMed

Zhang, Cheng-Pan; Vicic, David A

2012-01-11

Inexpensive nickel-bipyridine complexes were found to be active for the trifluoromethylthiolation of aryl iodides and aryl bromides at room temperature using the convenient [NMe(4)][SCF(3)] reagent. © 2011 American Chemical Society

Anticancer activity and anti-inflammatory studies of 5-aryl-1,4-benzodiazepine derivatives.

PubMed

Sandra, Cortez-Maya; Eduardo, Cortes Cortes; Simon, Hernandez-Ortega; Teresa, Ramirez Apan; Antonio, Nieto Camacho; Lijanova, Irina V; Marcos, Martinez-Garcia

2012-07-01

A series of 5-aryl-1,4-benzodiazepines with chloro- or fluoro-substituents in the second ring have been synthesized and their anti-inflammatory, myeloperoxidase and anticancer properties studied. The synthesized compounds showed potential anti-inflammatory and anticancer activities, which were enhanced in the presence of a chloro-substituent in the second ring of the 5-aryl-1,4- benzodiazepine.

Anaerobic Aryl Reductive Dehalogenation of Halobenzoates by Cell Extracts of “Desulfomonile tiedjei”

PubMed Central

DeWeerd, Kim A.; Suflita, Joseph M.

1990-01-01

We studied the transformation of halogenated benzoates by cell extracts of a dehalogenating anaerobe, “Desulfomonile tiedjei.” We found that cell extracts possessed aryl reductive dehalogenation activity. The activity was heat labile and dependent on the addition of reduced methyl viologen, but not on that of reduced NAD, NADP, flavin mononucleotide, flavin adenine dinucleotide, desulfoviridin, cytochrome c3, or benzyl viologen. Dehalogenation activity in extracts was stimulated by formate, CO, or H2, but not by pyruvate plus coenzyme A or by dithionite. The pH and temperature optima for aryl dehalogenation were 8.2 and 35°C, respectively. The rate of dehalogenation was proportional to the amount of protein in the assay mixture. The substrate specificity of aryl dehalogenation activity for various aromatic compounds in “D. tiedjei” cell extracts was identical to that of whole cells, except differences were observed in the relative rates of halobenzoate transformation. Dehalogenation was 10-fold greater in “D. tiedjei” extracts prepared from cells cultured in the presence of 3-chlorobenzoate, suggesting that the activity was inducible. Aryl reductive dehalogenation in extracts was inhibited by sulfite, sulfide, and thiosulfate, but not sulfate. Experiments with combinations of substrates suggested that cell extracts dehalogenated 3-iodobenzoate more readily than either 3,5-dichlorobenzoate or 3-chlorobenzoate. Dehalogenation activity was found to be membrane associated. This is the first report characterizing aryl dehalogenation activity in cell extracts of an obligate anaerobe. PMID:16348308

New aromatic activated dihalides and bisphenol monomers for the preparation of novel poly(arylene ethers)

NASA Technical Reports Server (NTRS)

Wolfe, James F.

1993-01-01

The goal of this research program was to synthesize a series of unique monomers of type I to be utilized at NASA-Langley in the preparation of new poly(arylene ether ketones), poly(arylene ether ketosulfones), and poly(arylene ether ketophosphine oxides). These A-A and A-B monomer systems, which possess activated aryl halide and/or phenolic end groups, are accessible via condensation reactions of appropriately substituted aryl acetonitrile carbanions with activated aryl dihalides followed by oxidative decyanation.

R-carrying genotypes of serum paraoxonase (PON1) 192 polymorphism and higher activity ratio are related to susceptibility against ischemic stroke.

PubMed

Mahrooz, Abdolkarim; Gohari, Ghorban; Hashemi, Mohammad-Bagher; Zargari, Mehryar; Musavi, Hadis; Abedini, Mahmoud; Alizadeh, Ahad

2012-12-01

The polymorphic gene of serum paraoxonase (PON1) and its activity involved in atherosclerosis. The purpose of the study was to analyze PON1 192 Q/R polymorphism and the enzyme activities in ischemic stroke. The polymorphism as the most common polymorphism in PON1 gene coding sequence is associated with variation in the enzyme activity and vascular disease. The study included 85 stroke patients and 71 control subjects. PON1 192 polymorphism was genotyped using PCR protocol. Paraoxonase activity (Para) and arylesterase activity (Aryl) were determined spectrophotometrically using paraoxon and phenylacetate as the substrates. The QR and RR genotypes were more frequent in stroke population compared to controls, resulting in a higher frequency of the R allele in patients (0.24 vs 0.18, OR = 1.41). Patients had significantly higher Para/Aryl ratio than that of controls (P = 0.016). In stroke patients, Para/Aryl and Para/HDL ratios increased with this order: QQ < QR < RR. Hypertension significantly increased the risk of ischemic stroke by 15-fold among R-containing people, while this was significantly increased 4-fold for QQ homozygotes. Smoking increased the risk of having ischemic stroke in both QQ homozygote and QR + RR group (OR = 2.84 and OR = 2.33, respectively). In conclusion, these data highlight the importance of PON1 192 R allele and high Para/Aryl ratio in susceptibility to ischemic stroke in the population. The presence of the 192 R allele potentiates the risk of stroke especially in hypertensive people. Decreased Aryl and increased Para/Aryl, Para/HDL and Aryl/HDL ratios may be markers indicated the increased susceptibility to ischemic stroke in the population.

Versatile Alkylation of (Hetero)Aryl Iodides with Ketones via β-C(sp3)-H Activation.

PubMed

Zhu, Ru-Yi; Liu, Luo-Yan; Park, Han Seul; Hong, Kai; Wu, Yongwei; Senanayake, Chris H; Yu, Jin-Quan

2017-11-15

We report Pd(II)-catalyzed β-C(sp 3 )-H (hetero)arylation of a variety of ketones using a commercially available 2,2-dimethyl aminooxyacetic acid auxiliary. Facile installation and removal of the auxiliary as well as its superior scope for both ketones and (hetero)aryl iodides overcome the significant limitations of the previously reported β-C(sp 3 )-H arylation of ketones. The ready availability of ketones renders this reaction a broadly useful method for alkyl-(hetero)aryl coupling involving both primary and secondary alkyls.

Synthesis and biological screening of 2'-aryl/benzyl-2-aryl-4-methyl-4',5-bithiazolyls as possible anti-tubercular and antimicrobial agents.

PubMed

Abhale, Yogita K; Sasane, Amit V; Chavan, Abhijit P; Deshmukh, Keshav K; Kotapalli, Sudha Sravanti; Ummanni, Ramesh; Sayyad, Sadikali F; Mhaske, Pravin C

2015-04-13

A series of 2'-aryl/benzyl-2-aryl-4-methyl-4',5-bithiazolyl derivatives, 25-64 were synthesized and evaluated for inhibitory activity against Mycobacterium smegmatis MC(2) 155 strain and antimicrobial activities against four pathogenic bacteria Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Proteus vulgaris. Among them, compounds 40, 49, 50, and 54 exhibited moderate to good inhibition on the growth of the bacteria Mycobacterium smegmatis at the concentration of 30 μM. Compounds 26, 40, 44, 54 and 56 exhibited moderate to good antibacterial activity. Compound 5-(2'-(4-fluorobenzyl)thiazol-4'-yl)-2-(4-fluorophenyl)-4-methyl-thiazole (54) exhibited both antitubercular as well as antimicrobial activity against all tested strains. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

Excessive activation of AhR signaling disrupts neuronal migration in the hippocampal CA1 region in the developing mouse.

PubMed

Kimura, Eiki; Kubo, Ken-Ichiro; Endo, Toshihiro; Nakajima, Kazunori; Kakeyama, Masaki; Tohyama, Chiharu

2017-01-01

The aryl hydrocarbon receptor (AhR) avidly binds dioxin, a ubiquitous environmental contaminant. Disruption of downstream AhR signaling has been reported to alter neuronal development, and rodent offspring exposed to dioxin during gestation and lactation showed abnormalities in learning and memory, emotion, and social behavior. However, the mechanism behind the disrupted AhR signaling and developmental neurotoxicity induced by xenobiotic ligands remains elusive. Therefore, we studied how excessive AhR activation affects neuronal migration in the hippocampal CA1 region of the developing mouse brain. We transfected constitutively active (CA)-AhR, AhR, or control vector plasmids into neurons via in utero electroporation on gestational day 14 and analyzed neuronal positioning in the hippocampal CA1 region of offspring on postnatal day 14. CA-AhR transfection affected neuronal positioning, whereas no change was observed in AhR-transfected or control hippocampus. These results suggest that constitutively activated AhR signaling disrupts neuronal migration during hippocampal development. Further studies are needed to investigate whether such developmental disruption in the hippocampus leads to the abnormal cognition and behavior of rodent offspring upon maternal exposure to AhR xenobiotic ligands.

N-heterocycle carbene (NHC)-ligated cyclopalladated N,N-dimethylbenzylamine: a highly active, practical and versatile catalyst for the Heck-Mizoroki reaction.

PubMed

Peh, Guang-Rong; Kantchev, Eric Assen B; Zhang, Chi; Ying, Jackie Y

2009-05-21

The wide dissemination of catalytic protocols in academic and industrial laboratories is facilitated by the development of catalysts that are not only highly active but also user-friendly, stable to moisture, air and long term storage and easy to prepare on a large scale. Herein we describe a protocol for the Heck-Mizoroki reaction mediated by cyclopalladated N,N-dimethylbenzylamine (dmba) ligated with a N-heterocyclic carbene, 1,3-bis(mesityl)imidazol-2-ylidene (IMes), that fulfils these criteria. The precatalyst can be synthesized on approximately 100 g scale by a tri-component, sequential, one-pot reaction of N,N-dimethylbenzylamine, PdCl2 and IMes.HCl in refluxing acetonitrile in air in the presence of K2CO3. This single component catalyst is stable to air, moisture and long term storage and can be conveniently dispensed as a stock solution in NMP. It mediates the Heck-Mizoroki reaction of a range of aryl- and heteroaryl bromides in reagent grade NMP at the 0.1-2 mol% range without the need for rigorous anhydrous techniques or a glovebox, and is active even in air. The catalyst is capable of achieving very high levels of catalytic activity (TON of up to 5.22 x 10(5)) for the coupling of a deactivated arylbromide, p-bromoanisole, with tBu acrylate as a benchmark substrate pair. A wide range of aryl bromides, iodides and, for the first time with a NHC-Pd catalyst, a triflate was coupled with diverse acrylate derivatives (nitrile, tert-butyl ester and amides) and styrene derivatives. The use of excess (>2 equiv.) of the aryl bromide and tert-butyl acrylate leads to mixture of tert-butyl beta,beta-diarylacrylate and tert-butyl cinnamate derivatives depending on the substitution pattern of the aryl bromide. Electron rich m- and p-substituted arylbromides give the diarylated products exclusively, whereas electron-poor aryl bromides give predominantly mono-arylated products. For o-substituted aryl bromides, no doubly arylated products could be obtained under any conditions. Overall, the active catalyst (IMes-Pd) shows higher activity with electron-rich aryl halides, a marked difference compared with the more commonly used phosphane-Pd or non-ligated Pd catalysts.

Methoxy-Directed Aryl-to-Aryl 1,3-Rhodium Migration

PubMed Central

Zhang, Jing; Liu, Jun-Feng; Ugrinov, Angel; Pillai, Anthony F. X.; Sun, Zhong-Ming; Zhao, Pinjing

2015-01-01

Through-space metal/hydrogen shift is an important strategy for transition metal-catalyzed C-H bond activation. Here we describe the synthesis and characterization of a Rh(I) 2,6-dimethoxybenzoate complex that underwent stoichiometric rearrangement via a highly unusual 1,3- rhodium migration. This aryl-to-aryl 1,3-Rh/H shift was also demonstrated in a Rh(I)-catalyzed decarboxylative conjugate addition to form a C-C bond at a meta position instead of the ipso-carboxyl position. A deuterium-labeling study under the conditions of Rh(I)-catalyzed protodecarboxylation revealed the involvement of an ortho-methoxy group in a multi-step pathway of consecutive sp3 and sp2 C-H bond activations. PMID:24171626

New mechanistic insights regarding Pd/Cu catalysts for the Sonogashira reaction: HRMAS NMR studies of silica-immobilized systems.

PubMed

Posset, Tobias; Blümel, Janet

2006-07-05

The title technique, high-resolution magic angle spinning NMR of suspensions, constitutes a powerful new tool for investigating the structures and mobilities of immobilized species and, thus, for optimizing heterobimetallic catalyst systems, such as the Sonogashira coupling of terminal alkynes and aryl halides.

The photocatalyzed Meerwein arylation: classic reaction of aryl diazonium salts in a new light.

PubMed

Hari, Durga Prasad; König, Burkhard

2013-04-26

The use of diazonium salts for aryl radical generation and C-H arylation processes has been known since 1896 when Pschorr first used the reaction for intramolecular cyclizations. Meerwein developed it further in the early 1900s into a general arylation method. However, this reaction could not compete with the transition-metal-mediated formation of C(sp(2))-C(sp(2)) bonds. The replacement of the copper catalyst with iron and titanium compounds improved the situation, but the use of photocatalysis to induce the one-electron reduction and activation of the diazonium salts is even more advantageous. The first photocatalyzed Pschorr cyclization was published in 1984, and just last year a series of papers described applications of photocatalytic Meerwein arylations leading to aryl-alkene coupling products. In this Minireview we summarize the origins of this reaction and its scope and applications. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Development of 1-aryl-3-furanyl/thienyl-imidazopyridine templates for inhibitors against hypoxia inducible factor (HIF)-1 transcriptional activity.

PubMed

Fuse, Shinichiro; Ohuchi, Toshiaki; Asawa, Yasunobu; Sato, Shinichi; Nakamura, Hiroyuki

2016-12-15

1,3-Disubstituted-imidazopyridines were designed for developing inhibitors against HIF-1 transcriptional activity. Designed compounds were rapidly synthesized from a key aromatic scaffold via microwave-assisted Suzuki-Miyaura coupling/CH direct arylation sequence. Evaluation of ability to inhibit the hypoxia induced transcriptional activity of HIF-1 revealed that the compound 2i and 3a retained the same level of the inhibitory activity comparing with that of known inhibitor, YC-1 (1). Identified, readily accessible 1-aryl-3-furanyl/thienyl-imidazopyridine templates should be useful for future drug development. Copyright © 2016 Elsevier Ltd. All rights reserved.

Modulation of the Substitution Pattern of 5-Aryl-2-Aminoimidazoles Allows Fine-Tuning of Their Antibiofilm Activity Spectrum and Toxicity

PubMed Central

Peeters, Elien; Hooyberghs, Geert; Robijns, Stijn; Waldrant, Kai; De Weerdt, Ami; Delattin, Nicolas; Liebens, Veerle; Kucharíková, Soňa; Tournu, Hélène; Verstraeten, Natalie; Dovgan, Barbara; Girandon, Lenart; Fröhlich, Mirjam; De Brucker, Katrijn; Michiels, Jan; Cammue, Bruno P. A.; Thevissen, Karin; Vanderleyden, Jozef; Van der Eycken, Erik

2016-01-01

We previously synthesized several series of compounds, based on the 5-aryl-2-aminoimidazole scaffold, that showed activity preventing the formation of Salmonella enterica serovar Typhimurium and Pseudomonas aeruginosa biofilms. Here, we further studied the activity spectrum of a number of the most active N1- and 2N-substituted 5-aryl-2-aminoimidazoles against a broad panel of biofilms formed by monospecies and mixed species of bacteria and fungi. An N1-substituted compound showed very strong activity against the biofilms formed by Gram-negative and Gram-positive bacteria and the fungus Candida albicans but was previously shown to be toxic against various eukaryotic cell lines. In contrast, 2N-substituted compounds were nontoxic and active against biofilms formed by Gram-negative bacteria and C. albicans but had reduced activity against biofilms formed by Gram-positive bacteria. In an attempt to develop nontoxic compounds with potent activity against biofilms formed by Gram-positive bacteria for application in antibiofilm coatings for medical implants, we synthesized novel compounds with substituents at both the N1 and 2N positions and tested these compounds for antibiofilm activity and toxicity. Interestingly, most of these N1-,2N-disubstituted 5-aryl-2-aminoimidazoles showed very strong activity against biofilms formed by Gram-positive bacteria and C. albicans in various setups with biofilms formed by monospecies and mixed species but lost activity against biofilms formed by Gram-negative bacteria. In light of application of these compounds as anti-infective coatings on orthopedic implants, toxicity against two bone cell lines and the functionality of these cells were tested. The N1-,2N-disubstituted 5-aryl-2-aminoimidazoles in general did not affect the viability of bone cells and even induced calcium deposition. This indicates that modulating the substitution pattern on positions N1 and 2N of the 5-aryl-2-aminoimidazole scaffold allows fine-tuning of both the antibiofilm activity spectrum and toxicity. PMID:27550355

N,N-Diethylurea-Catalyzed Amidation between Electron-Defficient Aryl Azides and Phenylacetaldehydes

PubMed Central

Xie, Sheng; Ramström, Olof; Yan, Mingdi

2015-01-01

Urea structures, of which N,N-diethylurea (DEU) proved to be the most efficient, were discovered to catalyze amidation reactions between electron-defficient aryl azides and phenylacetaldehydes. Experimental data support 1,3-dipolar cycloaddition between DEU-activated enols and electrophilic phenyl azides, especially perfluoroaryl azides, followed by rearrangement of the triazoline intermediate. The activation of the aldehyde under near-neutral conditions was of special importance in inhibiting dehydration/aromatization of the triazoline intermediate, thus promoting the rearrangement to form aryl amides. PMID:25616121

Application of a Heterogeneous Chiral Titanium Catalyst Derived from Silica-Supported 3-Aryl H8-BINOL to Enantioselective Alkylation and Arylation of Aldehydes.

PubMed

Akai, Junichiro; Watanabe, Satoshi; Michikawa, Kumiko; Harada, Toshiro

2017-07-07

A 3-aryl H 8 -BINOL was grafted on the surface of silica gel using a hydrosilane derivative as a precursor, and the resulting silica-supported ligand (6 mol %) was employed in the enantioselective alkylation and arylation of aldehydes in the presence of Ti(O i Pr) 4 . The reactions using Et 2 Zn, Et 3 B, and aryl Grignard reagents all afforded the corresponding adducts in high enantioselectivities and yields. The silica-immobilized titanium catalyst could be reused up to 14 times without appreciable deterioration of the activity.

Molecular characterization of a novel bacterial aryl acylamidase belonging to the amidase signature enzyme family.

PubMed

Ko, Hyeok-Jin; Lee, Eun Woo; Bang, Won-Gi; Lee, Cheol-Koo; Kim, Kyoung Heon; Choi, In-Geol

2010-05-01

In seeking aryl acylamidase (EC 3.5.1.13) acting on an amide bond in p-acetaminophenol (Tylenol), we identified a novel gene encoding 496 residues of a protein. The gene revealed a conserved amidase signature region with a canonical catalytic triad. The gene was expressed in E. coli and characterized for its biochemical properties. The optimum pH and temperature for the activity on p-acetaminophenol were 10 and 37 degrees C, respectively. The half-life of enzyme activity at 37 degrees C was 192 h and 90% of its activity remained after 3 h incubation at 40 degrees C. Divalent metals was found to inhibit the activity of enzyme. The K (m) values for various aryl acylamides such as 4-nitroacetanilide, p-acetaminophenol, phenacetin, 4-chloroacetanilide and acetanilide were 0.10, 0.32, 0.83, 1.9 and 19 mM, respectively. The reverse reaction activity (amide synthesis) was also examined using various chain lengths (C(1) approximately C(4) and C(10)) of carboxylic donors and aniline as substrates. These kinetic parameters and substrate specificity in forward and reverse reaction indicated that the aryl acylamidase in this study has a preference for aryl substrate having polar functional groups and hydrophobic carboxylic donors.

Copper-Catalyzed C(sp2)-S Coupling Reactions for the Synthesis of Aryl Dithiocarbamates with Thiuram Disulfide Reagents.

PubMed

Dong, Zhi-Bing; Liu, Xing; Bolm, Carsten

2017-11-03

An efficient protocol for the copper-catalyzed preparation of aryl dithiocarbamates from aryl iodides and inexpensive, environmentally benign tetraalkylthiuram disulfides was developed. The features of mild reaction conditions, high yields, and broad substrate scope render this new approach synthetically attractive for the preparation of potentially biologically active compounds.

NiXantphos: a deprotonatable ligand for room-temperature palladium-catalyzed cross-couplings of aryl chlorides.

PubMed

Zhang, Jiadi; Bellomo, Ana; Trongsiriwat, Nisalak; Jia, Tiezheng; Carroll, Patrick J; Dreher, Spencer D; Tudge, Matthew T; Yin, Haolin; Robinson, Jerome R; Schelter, Eric J; Walsh, Patrick J

2014-04-30

Although the past 15 years have witnessed the development of sterically bulky and electron-rich alkylphosphine ligands for palladium-catalyzed cross-couplings with aryl chlorides, examples of palladium catalysts based on either triarylphosphine or bidentate phosphine ligands for efficient room temperature cross-coupling reactions with unactivated aryl chlorides are rare. Herein we report a palladium catalyst based on NiXantphos, a deprotonatable chelating aryldiphosphine ligand, to oxidatively add unactivated aryl chlorides at room temperature. Surprisingly, comparison of an extensive array of ligands revealed that under the basic reaction conditions the resultant heterobimetallic Pd-NiXantphos catalyst system outperformed all the other mono- and bidentate ligands in a deprotonative cross-coupling process (DCCP) with aryl chlorides. The DCCP with aryl chlorides affords a variety of triarylmethane products, a class of compounds with various applications and interesting biological activity. Additionally, the DCCP exhibits remarkable chemoselectivity in the presence of aryl chloride substrates bearing heteroaryl groups and sensitive functional groups that are known to undergo 1,2-addition, aldol reaction, and O-, N-, enolate-α-, and C(sp(2))-H arylations. The advantages and importance of the Pd-NiXantphos catalyst system outlined herein make it a valuable contribution for applications in Pd-catalyzed arylation reactions with aryl chlorides.

NiXantphos: A Deprotonatable Ligand for Room-Temperature Palladium-Catalyzed Cross-Couplings of Aryl Chlorides

PubMed Central

2015-01-01

Although the past 15 years have witnessed the development of sterically bulky and electron-rich alkylphosphine ligands for palladium-catalyzed cross-couplings with aryl chlorides, examples of palladium catalysts based on either triarylphosphine or bidentate phosphine ligands for efficient room temperature cross-coupling reactions with unactivated aryl chlorides are rare. Herein we report a palladium catalyst based on NiXantphos, a deprotonatable chelating aryldiphosphine ligand, to oxidatively add unactivated aryl chlorides at room temperature. Surprisingly, comparison of an extensive array of ligands revealed that under the basic reaction conditions the resultant heterobimetallic Pd–NiXantphos catalyst system outperformed all the other mono- and bidentate ligands in a deprotonative cross-coupling process (DCCP) with aryl chlorides. The DCCP with aryl chlorides affords a variety of triarylmethane products, a class of compounds with various applications and interesting biological activity. Additionally, the DCCP exhibits remarkable chemoselectivity in the presence of aryl chloride substrates bearing heteroaryl groups and sensitive functional groups that are known to undergo 1,2-addition, aldol reaction, and O-, N-, enolate-α-, and C(sp2)–H arylations. The advantages and importance of the Pd–NiXantphos catalyst system outlined herein make it a valuable contribution for applications in Pd-catalyzed arylation reactions with aryl chlorides. PMID:24745758

Bacillus subtilis mutant LicT antiterminators exhibiting enzyme I- and HPr-independent antitermination affect catabolite repression of the bglPH operon.

PubMed

Lindner, Cordula; Hecker, Michael; Le Coq, Dominique; Deutscher, Josef

2002-09-01

The Bacillus subtilis antiterminator LicT regulates the expression of bglPH and bglS, which encode the enzymes for the metabolism of aryl-beta-glucosides and the beta-glucanase BglS. The N-terminal domain of LicT (first 55 amino acids) prevents the formation of rho-independent terminators on the respective transcripts by binding to target sites overlapping these terminators. Proteins of the phosphoenolpyruvate:carbohydrate phosphotransferase system (PTS) regulate the antitermination activity of LicT by phosphorylating histidines in its two PTS regulation domains (PRDs). Phosphorylation at His-100 in PRD-1 requires the PTS proteins enzyme I and HPr and the phosphorylated permease BglP and inactivates LicT. During transport and phosphorylation of aryl-beta-glucosides, BglP is dephosphorylated, which renders LicT active and thus leads to bglPH and bglS induction. In contrast, phosphorylation at His-207 and/or His-269 in PRD-2, which requires only enzyme I and HPr, is absolutely necessary for LicT activity and bglPH and bglS expression. We isolated spontaneous licT mutants expressing bglPH even when enzyme I and HPr were absent (as indicated by the designation "Pia" [PTS-independent antitermination]). Introduced in a ptsHI(+) strain, two classes of licT(Pia) mutations could be distinguished. Mutants synthesizing LicT(Pia) antiterminators altered in PRD-2 still required induction by aryl-beta-glucosides, whereas mutations affecting PRD-1 caused constitutive bglPH expression. One of the two carbon catabolite repression (CCR) mechanisms operative for bglPH requires the rho-independent terminator and is probably prevented when LicT is activated by P approximately His-HPr-dependent phosphorylation in PRD-2 (where the prefix "P approximately " stands for "phospho"). During CCR, the small amount of P approximately His-HPr present in cells growing on repressing PTS sugars probably leads to insufficient phosphorylation at PRD-2 of LicT and therefore to reduced bglPH expression. In agreement with this concept, mutants synthesizing a P approximately His-HPr-independent LicT(Pia) had lost LicT-modulated CCR.

Bacillus subtilis Mutant LicT Antiterminators Exhibiting Enzyme I- and HPr-Independent Antitermination Affect Catabolite Repression of the bglPH Operon

PubMed Central

Lindner, Cordula; Hecker, Michael; Le Coq, Dominique; Deutscher, Josef

2002-01-01

The Bacillus subtilis antiterminator LicT regulates the expression of bglPH and bglS, which encode the enzymes for the metabolism of aryl-β-glucosides and the β-glucanase BglS. The N-terminal domain of LicT (first 55 amino acids) prevents the formation of ρ-independent terminators on the respective transcripts by binding to target sites overlapping these terminators. Proteins of the phosphoenolpyruvate:carbohydrate phosphotransferase system (PTS) regulate the antitermination activity of LicT by phosphorylating histidines in its two PTS regulation domains (PRDs). Phosphorylation at His-100 in PRD-1 requires the PTS proteins enzyme I and HPr and the phosphorylated permease BglP and inactivates LicT. During transport and phosphorylation of aryl-β-glucosides, BglP is dephosphorylated, which renders LicT active and thus leads to bglPH and bglS induction. In contrast, phosphorylation at His-207 and/or His-269 in PRD-2, which requires only enzyme I and HPr, is absolutely necessary for LicT activity and bglPH and bglS expression. We isolated spontaneous licT mutants expressing bglPH even when enzyme I and HPr were absent (as indicated by the designation “Pia” [PTS-independent antitermination]). Introduced in a ptsHI+ strain, two classes of licT(Pia) mutations could be distinguished. Mutants synthesizing LicT(Pia) antiterminators altered in PRD-2 still required induction by aryl-β-glucosides, whereas mutations affecting PRD-1 caused constitutive bglPH expression. One of the two carbon catabolite repression (CCR) mechanisms operative for bglPH requires the ρ-independent terminator and is probably prevented when LicT is activated by P∼His-HPr-dependent phosphorylation in PRD-2 (where the prefix “P∼” stands for “phospho”). During CCR, the small amount of P∼His-HPr present in cells growing on repressing PTS sugars probably leads to insufficient phosphorylation at PRD-2 of LicT and therefore to reduced bglPH expression. In agreement with this concept, mutants synthesizing a P∼His-HPr-independent LicT(Pia) had lost LicT-modulated CCR. PMID:12169607

Copper(II)-catalyzed hydroxylation of aryl halides using glycolic acid as a ligand.

PubMed

Xiao, Yan; Xu, Yongnan; Cheon, Hwan-Sung; Chae, Junghyun

2013-06-07

Copper(II)-catalyzed hydroxylation of aryl halides has been developed to afford functionalized phenols. The protocol utilizes the reagent combination of Cu(OH)2, glycolic acid, and NaOH in aqueous DMSO, all of which are cheap, readily available, and easily removable after the reaction. A broad range of aryl iodides and activated aryl bromides were transformed into the corresponding phenols in excellent yields. Moreover, it has been shown that C-O(alkyl)-coupled product, instead of phenol, can be predominantly formed under similar reaction conditions.

Design and synthesis of aryl ether and sulfone hydroxamic acids as potent histone deacetylase (HDAC) inhibitors.

PubMed

Pabba, Chittari; Gregg, Brian T; Kitchen, Douglas B; Chen, Zhen Jia; Judkins, Angela

2011-01-01

A series of novel hydroxamic acid based histone deacetylases (HDAC) inhibitors with aryl ether and aryl sulfone residues at the terminus of a substituted, unsaturated 5-carbon spacer moiety have been synthesized for the first time and evaluated. Compounds with meta- and para-substitution on the aryl ring of ether hydroxamic acids 19c, 20c, 19e, 19f and 19g are potent HDAC inhibitors with activities at low nanomolar levels. Copyright © 2010 Elsevier Ltd. All rights reserved.

Palladium-Catalyzed Coupling of Ammonia with Aryl Chlorides, Bromides, Iodides and Sulfonates: A General Method for the Preparation of Primary Arylamines

PubMed Central

Vo, Giang D.

2010-01-01

We report that the complex generated from Pd[P(o-tol)3]2 and the alkylbisphosphine CyPF-t-Bu is a highly active and selective catalyst for the coupling of ammonia with aryl chlorides, bromides, iodides, and sulfonates. The couplings of ammonia with this catalyst conducted with a solution of ammonia in dioxane form primary arylamines from a variety of aryl electrophiles in high yields. Catalyst loadings as low as 0.1 mol % were sufficient for reactions of many aryl chlorides and bromides. In the presence of this catalyst, aryl sulfonates also coupled with ammonia for the first time in high yields. A comparison of reactions in the presence of this catalyst versus those in the presence of existing copper and palladium systems revealed a complementary, if not broader substrate scope. The utility of this method to generate amides, imides and carbamates is illustrated by a one-pot synthesis of a small library of these carbonyl compounds from aryl bromides and chlorides. Mechanistic studies show that Pd[P(o-tol)3]2 and CyPF-t-Bu generate a more active and general catalyst than that generated from CyPF-t-Bu and palladiun(II) precursors because of the low concentration of active catalyst that is generated from the combination of palladium(II), ammonia and base. PMID:19591470

Influence of sulfur oxyanions on reductive dehalogenation activities in Desulfomonile tiedjei.

PubMed Central

Townsend, G T; Suflita, J M

1997-01-01

The inhibition of aryl reductive dehalogenation reactions by sulfur oxyanions has been demonstrated in environmental samples, dehalogenating enrichments, and the sulfate-reducing bacterium Desulfomonile tiedjei; however, this phenomenon is not well understood. We examined the effects of sulfate, sulfite, and thiosulfate on reductive dehalogenation in the model microorganism D. tiedjei and found separate mechanisms of inhibition due to these oxyanions under growth versus nongrowth conditions. Dehalogenation activity was greatly reduced in extracts of cells grown in the presence of both 3-chlorobenzoate, the substrate or inducer for the aryl dehalogenation activity, and either sulfate, sulfite, or thiosulfate, indicating that sulfur oxyanions repress the requisite enzymes. In extracts of fully induced cells, thiosulfate and sulfite, but not sulfate, were potent inhibitors of aryl dehalogenation activity even in membrane fractions lacking the cytoplasmically located sulfur oxyanion reductase. These results suggest that under growth conditions, sulfur oxyanions serve as preferred electron acceptors and negatively influence dehalogenation activity in D. tiedjei by regulating the amount of active aryl dehalogenase in cells. Additionally, in vitro inhibition by sulfur oxyanions is due to the interaction of the reactive species with enzymes involved in dehalogenation and need not involve competition between two respiratory processes for reducing equivalents. Sulfur oxyanions also inhibited tetrachloroethylene dehalogenation by the same mechanisms, further indicating that chloroethylenes are fortuitously dehalogenated by the aryl dehalogenase. The commonly observed inhibition of reductive dehalogenation reactions under sulfate-reducing conditions may be due to similar regulation mechanisms in other dehalogenating microorganisms that contain multiple respiratory activities. PMID:9293011

Design, synthesis and antimalarial evaluation of novel thiazole derivatives.

PubMed

Bueno, José María; Carda, Miguel; Crespo, Benigno; Cuñat, Ana Carmen; de Cozar, Cristina; León, María Luisa; Marco, J Alberto; Roda, Nuria; Sanz-Cervera, Juan F

2016-08-15

As part of our medicinal chemistry program's ongoing search for compounds with antimalarial activity, we prepared a series of thiazole analogs and conducted a SAR study analyzing their in vitro activities against the chloroquine-sensitive Plasmodium falciparum 3D7 strain. The results indicate that modifications of the N-aryl amide group linked to the thiazole ring are the most significant in terms of in vitro antimalarial activity, leading to compounds with high antimalarial potency and low cytotoxicity in HepG2 cell lines. Furthermore, the observed SAR implies that non-bulky, electron-withdrawing groups are preferred at ortho position on the phenyl ring, whereas small atoms such as H or F are preferred at para position. Finally, replacement of the phenyl ring by a pyridine affords a compound with similar potency, but with potentially better physicochemical properties which could constitute a new line of research for further studies. Copyright © 2016 Elsevier Ltd. All rights reserved.

Design, Synthesis, and Structure--Activity Relationship of New 2-Aryl-3,4-dihydro-β-carbolin-2-ium Salts as Antifungal Agents.

PubMed

Hou, Zhe; Zhu, Li-Fei; Yu, Xin-chi; Sun, Ma-Qiang; Miao, Fang; Zhou, Le

2016-04-13

Twenty-two 2-aryl-9-methyl-3,4-dihydro-β-carbolin-2-ium bromides along with four 9-demethylated derivatives were synthesized and characterized by spectroscopic analysis. By using the mycelium growth rate method, the compounds were evaluated for antifungal activities in vitro against six plant pathogenic fungi, and structure-activity relationships (SAR) were derived. Almost all of the compounds showed obvious inhibition activity on each of the fungi at 150 μM. For all of the fungi, 10 of the compounds showed average inhibition rates of >80% at 150 μM, and most of their EC50 values were in the range of 2.0-30.0 μM. SAR analysis showed that the substitution pattern of the N-aryl ring significantly influences the activity; N9-alkylation improves the activity, whereas aromatization of ring-C reduces the activity. It was concluded that the present research provided a series of new 2-aryl-9-alkyl-3,4-dihydro-β-carbolin-2-iums with excellent antifungal potency and structure optimization design for the development of new carboline antifungal agents.

Targeting Integrin-Dependent Adhesion and Signaling with 3-Arylquinoline and 3-Aryl-2-Quinolone Derivatives: A new Class of Integrin Antagonists

PubMed Central

Fiorucci, Sandrine; Lin, Xiaochen; Sadoul, Karin; Fournet, Guy; Bouvard, Daniel; Vinogradova, Olga; Joseph, Benoît; Block, Marc R.

2015-01-01

We previously reported the anti-migratory function of 3-aryl-2-quinolone derivatives, chemically close to flavonoids (Joseph et al., 2002). Herein we show that 3-arylquinoline or 3-aryl-2-quinolone derivatives disrupt cell adhesion in a dose dependent and reversible manner yet antagonized by artificial integrin activation such as manganese. Relying on this anti-adhesive activity, a Structure-Activity Relationship (SAR) study was established on 20 different compounds to throw the bases of future optimization strategies. Active drugs efficiently inhibit platelet spreading, aggregation, and clot retraction, processes that rely on αllbβ3 integrin activation and clustering. In vitro these derivatives interfere with β3 cytoplasmic tail interaction with kindlin-2 in pulldown assays albeit little effect was observed with pure proteins suggesting that the drugs may block an alternative integrin activation process that may not be directly related to kindlin recruitment. Ex vivo, these drugs blunt integrin signaling assayed using focal adhesion kinase auto-phosphorylation as a read-out. Hence, 3-arylquinoline and 3-aryl-2-quinolone series are a novel class of integrin activation and signaling antagonists. PMID:26509443

Palladium- and Copper-Catalyzed Arylation of Carbon-Hydrogen Bonds

PubMed Central

Daugulis, Olafs; Do, Hien-Quang; Shabashov, Dmitry

2010-01-01

The transition-metal-catalyzed functionalization of C-H bonds is a powerful method for generating carbon-carbon bonds. Although significant advances to this field have been reported during the last decade, many challenges remain. First, most of the methods are substrate-specific and thus cannot be generalized. Second, conversions of unactivated (i.e. not benzylic or alpha to heteroatom) sp3 C–H bonds to C–C bonds are rare, with most examples limited to t-butyl groups—a conversion that is inherently simple because there are no β-hydrogens that can be eliminated. Finally, the palladium, rhodium, and ruthenium catalysts routinely used for the conversion of C–H bonds to C–C bonds are expensive. Catalytically active metals that are cheaper and less exotic (e.g. copper, iron, and manganese) are rarely used. This Account describes our attempts to provide solutions to these three problems. We have developed a general method for directing-group-containing arene arylation by aryl iodides. Using palladium acetate as the catalyst, we arylated anilides, benzamides, benzoic acids, benzylamines, and 2-substituted pyridine derivatives under nearly identical conditions. We have also developed a method for the palladium-catalyzed auxiliary-assisted arylation of unactivated sp3 C–H bonds. This procedure allows for the β-arylation of carboxylic acid derivatives and the γ-arylation of amine derivatives. Furthermore, copper catalysis can be used to mediate the arylation of acidic arene C–H bonds (i.e. those with pKa values <35 in DMSO). Using a copper iodide catalyst in combination with a base and a phenanthroline ligand, we successfully arylated electron-rich and electron-deficient heterocycles and electron-poor arenes possessing at least two electron-withdrawing groups. The reaction exhibits unusual regioselectivity: arylation occurs at the most hindered position. This copper-catalyzed method supplements the well-known C–H activation/borylation methodology, in which functionalization usually occurs at the least hindered position. We also describe preliminary investigations to determine the mechanisms of these transformations. We anticipate that other transition metals, including iron, nickel, cobalt, and silver, will also be able to facilitate deprotonation/arylation reaction sequences. PMID:19552413

Palladium- and copper-catalyzed arylation of carbon-hydrogen bonds.

PubMed

Daugulis, Olafs; Do, Hien-Quang; Shabashov, Dmitry

2009-08-18

The transition-metal-catalyzed functionalization of C-H bonds is a powerful method for generating carbon-carbon bonds. Although significant advances to this field have been reported during the past decade, many challenges remain. First, most of the methods are substrate-specific and thus cannot be generalized. Second, conversions of unactivated (i.e., not benzylic or alpha to heteroatom) sp(3) C-H bonds to C-C bonds are rare, with most examples limited to t-butyl groups, a conversion that is inherently simple because there are no beta-hydrogens that can be eliminated. Finally, the palladium, rhodium, and ruthenium catalysts routinely used for the conversion of C-H bonds to C-C bonds are expensive. Catalytically active metals that are cheaper and less exotic (e.g., copper, iron, and manganese) are rarely used. This Account describes our attempts to provide solutions to these three problems. We have developed a general method for directing-group-containing arene arylation by aryl iodides. Using palladium acetate as the catalyst, we arylated anilides, benzamides, benzoic acids, benzylamines, and 2-substituted pyridine derivatives under nearly identical conditions. We have also developed a method for the palladium-catalyzed auxiliary-assisted arylation of unactivated sp(3) C-H bonds. This procedure allows for the beta-arylation of carboxylic acid derivatives and the gamma-arylation of amine derivatives. Furthermore, copper catalysis can be used to mediate the arylation of acidic arene C-H bonds (i.e., those with pK(a) values <35 in DMSO). Using a copper iodide catalyst in combination with a base and a phenanthroline ligand, we successfully arylated electron-rich and electron-deficient heterocycles and electron-poor arenes possessing at least two electron-withdrawing groups. The reaction exhibits unusual regioselectivity: arylation occurs at the most hindered position. This copper-catalyzed method supplements the well-known C-H activation/borylation methodology, in which functionalization usually occurs at the least hindered position. We also describe preliminary investigations to determine the mechanisms of these transformations. We anticipate that other transition metals, including iron, nickel, cobalt, and silver, will also be able to facilitate deprotonation/arylation reaction sequences.

Cloning, expression and characterization of an aryl-alcohol dehydrogenase from the white-rot fungus Phanerochaete chrysosporium strain BKM-F-1767

PubMed Central

2012-01-01

Background The white-rot fungus Phanerochaete chrysosporium is among the small group of fungi that can degrade lignin to carbon dioxide while leaving the crystalline cellulose untouched. The efficient lignin oxidation system of this fungus requires cyclic redox reactions involving the reduction of aryl-aldehydes to the corresponding alcohols by aryl-alcohol dehydrogenase. However, the biochemical properties of this enzyme have not been extensively studied. These are of most interest for the design of metabolic engineering/synthetic biology strategies in the field of biotechnological applications of this enzyme. Results We report here the cloning of an aryl-alcohol dehydrogenase cDNA from the white-rot fungus Phanerochaete chrysosporium, its expression in Escherichia coli and the biochemical characterization of the encoded GST and His6 tagged protein. The purified recombinant enzyme showed optimal activity at 37°C and at pH 6.4 for the reduction of aryl- and linear aldehydes with NADPH as coenzyme. NADH could also be the electron donor, while having a higher Km (220 μM) compared to that of NADPH (39 μM). The purified recombinant enzyme was found to be active in the reduction of more than 20 different aryl- and linear aldehydes showing highest specificity for mono- and dimethoxylated Benzaldehyde at positions 3, 4, 3,4 and 3,5. The enzyme was also capable of oxidizing aryl-alcohols with NADP + at 30°C and an optimum pH of 10.3 but with 15 to 100-fold lower catalytic efficiency than for the reduction reaction. Conclusions In this work, we have characterized the biochemical properties of an aryl-alcohol dehydrogenase from the white-rot fungus Phanerochaete chrysosporium. We show that this enzyme functions in the reductive sense under physiological conditions and that it displays relatively large substrate specificity with highest activity towards the natural compound Veratraldehyde. PMID:22742413

Electronic states of aryl radical functionalized graphenes: Density functional theory study

NASA Astrophysics Data System (ADS)

Tachikawa, Hiroto; Kawabata, Hiroshi

2016-06-01

Functionalized graphenes are known as a high-performance molecular device. In the present study, the structures and electronic states of the aryl radical functionalized graphene have been investigated by the density functional theory (DFT) method to elucidate the effects of functionalization on the electronic states of graphene (GR). Also, the mechanism of aryl radical reaction with GR was investigated. The benzene, biphenyl, p-terphenyl, and p-quaterphenyl radicals [denoted by (Bz) n (n = 1-4), where n means numbers of benzene rings in aryl radical] were examined as aryl radicals. The DFT calculation of GR-(Bz) n (n = 1-4) showed that the aryl radical binds to the carbon atom of GR, and a C-C single bond was formed. The binding energies of aryl radicals to GR were calculated to be ca. 6.0 kcal mol-1 at the CAM-B3LYP/6-311G(d,p) level. It was found that the activation barrier exists in the aryl radical addition: the barrier heights were calculated to be 10.0 kcal mol-1. The electronic states of GR-(Bz) n were examined on the basis of theoretical results.

Synthesis and biological activity of a new class of insecticides: the N-(5-aryl-1,3,4-thiadiazol-2-yl)amides.

PubMed

Eckelbarger, Joseph D; Parker, Marshall H; Yap, Maurice Ch; Buysse, Ann M; Babcock, Jonathan M; Hunter, Ricky; Adelfinskaya, Yelena; Samaritoni, Jack G; Garizi, Negar; Trullinger, Tony K

2017-04-01

Optimization studies on a high-throughput screening (HTS) hit led to the discovery of a series of N-(6-arylpyridazin-3-yl)amides with insecticidal activity. It was hypothesized that the isosteric replacement of the pyridazine ring with a 1,3,4-thiadiazole ring could lead to more potent biological activity and/or a broader sap-feeding pest spectrum. The resulting N-(5-aryl-1,3,4-thiadiazol-2-yl)amides were explored as a new class of insecticides. Several methods for 2-amino-1,3,4-thiadiazole synthesis were used for the preparation of key synthetic intermediates. Subsequent coupling to variously substituted carboxylic acid building blocks furnished the final targets, which were tested for insecticidal activity against susceptible strains of Aphis gossypii (Glover) (cotton aphid), Myzus persicae (Sulzer) (green peach aphid) and Bemisia tabaci (Gennadius) (sweetpotato whitefly). Structure-activity relationship (SAR) studies on both the amide tail and the aryl A-ring of novel N-(5-aryl-1,3,4-thiadiazol-2-yl)amides led to a new class of insecticidal molecules active against sap-feeding insect pests. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

Visible-light-driven Photocatalytic N-arylation of Imidazole Derivatives and Arylboronic Acids on Cu/graphene catalyst

NASA Astrophysics Data System (ADS)

Cui, Yan-Li; Guo, Xiao-Ning; Wang, Ying-Yong; Guo, Xiang-Yun

2015-07-01

N-aryl imidazoles play an important role as structural and functional units in many natural products and biologically active compounds. Herein, we report a photocatalytic route for the C-N cross-coupling reactions over a Cu/graphene catalyst, which can effectively catalyze N-arylation of imidazole and phenylboronic acid, and achieve a turnover frequency of 25.4 h-1 at 25 oC and the irradiation of visible light. The enhanced catalytic activity of the Cu/graphene under the light irradiation results from the localized surface plasmon resonance of copper nanoparticles. The Cu/graphene photocatalyst has a general applicability for photocatalytic C-N, C-O and C-S cross-coupling of arylboronic acids with imidazoles, phenols and thiophenols. This study provides a green photocatalytic route for the production of N-aryl imidazoles.

The Aryl Hydrocarbon Receptor Binds to E2F1 and Inhibits E2F1-induced Apoptosis

PubMed Central

Marlowe, Jennifer L.; Fan, Yunxia; Chang, Xiaoqing; Peng, Li; Knudsen, Erik S.; Xia, Ying

2008-01-01

Cellular stress by DNA damage induces checkpoint kinase-2 (CHK2)-mediated phosphorylation and stabilization of the E2F1 transcription factor, leading to induction of apoptosis by activation of a subset of proapoptotic E2F1 target genes, including Apaf1 and p73. This report characterizes an interaction between the aryl hydrocarbon (Ah) receptor (AHR), a ligand-activated transcription factor, and E2F1 that results in the attenuation of E2F1-mediated apoptosis. In Ahr−/− fibroblasts stably transfected with a doxycycline-regulated AHR expression vector, inhibition of AHR expression causes a significant elevation of oxidative stress, γH2A.X histone phosphorylation, and E2F1-dependent apoptosis, which can be blocked by small interfering RNA-mediated knockdown of E2F1 expression. In contrast, ligand-dependent AHR activation protects these cells from etoposide-induced cell death. In cells expressing both proteins, AHR and E2F1 interact independently of the retinoblastoma protein (RB), because AHR and E2F1 coimmunoprecipitate from extracts of RB-negative cells. Additionally, chromatin immunoprecipitation assays indicate that AHR and E2F1 bind to the Apaf1 promoter at a region containing a consensus E2F1 binding site but no AHR binding sites. AHR activation represses Apaf1 and TAp73 mRNA induction by a constitutively active CHK2 expression vector. Furthermore, AHR overexpression blocks the transcriptional induction of Apaf1 and p73 and the accumulation of sub-G0/G1 cells resulting from ectopic overexpression of E2F1. These results point to a proproliferative, antiapoptotic function of the Ah receptor that likely plays a role in tumor progression. PMID:18524851

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

Recent Developments in C-H Activation for Materials Science in the Center for Selective C-H Activation.

PubMed

Zhang, Junxiang; Kang, Lauren J; Parker, Timothy C; Blakey, Simon B; Luscombe, Christine K; Marder, Seth R

2018-04-16

Abstract : Organic electronics is a rapidly growing field driven in large part by the synthesis of ∏-conjugated molecules and polymers. Traditional aryl cross-coupling reactions such as the Stille and Suzuki have been used extensively in the synthesis of ∏-conjugated molecules and polymers, but the synthesis of intermediates necessary for traditional cross-couplings can include multiple steps with toxic and hazardous reagents. Direct arylation through C-H bond activation has the potential to reduce the number of steps and hazards while being more atom-economical. Within the Center for Selective C-H Functionalization (CCHF), we have been developing C-H activation methodology for the synthesis of ∏-conjugated materials of interest, including direct arylation of difficult-to-functionalize electron acceptor intermediates and living polymerization of ∏-conjugated polymers through C-H activation.

Identification and characterization of 4-aryl-3,4-dihydropyrimidin-2(1H)-ones as inhibitors of the fatty acid transporter FATP4.

PubMed

Blackburn, Christopher; Guan, Bing; Brown, James; Cullis, Courtney; Condon, Stephen M; Jenkins, Tracy J; Peluso, Stephane; Ye, Yingchun; Gimeno, Ruth E; Punreddy, Sandhya; Sun, Ying; Wu, Hui; Hubbard, Brian; Kaushik, Virendar; Tummino, Peter; Sanchetti, Praveen; Yu Sun, Dong; Daniels, Tom; Tozzo, Effie; Balani, Suresh K; Raman, Prakash

2006-07-01

Several potent, cell permeable 4-aryl-dihydropyrimidinones have been identified as inhibitors of FATP4. Lipophilic ester substituents at the 5-position and substitution at the para-position (optimal groups being -NO(2) and CF(3)) of the 4-aryl group led to active compounds. In two cases racemates were resolved and the S enantiomers shown to have higher potencies.

Aryl-O reductive elimination from reaction of well-defined aryl-Cu(III) species with phenolates: the importance of ligand reactivity.

PubMed

Casitas, Alicia; Ioannidis, Nikolaos; Mitrikas, George; Costas, Miquel; Ribas, Xavi

2011-09-21

Well-defined aryl-Cu(III) species undergo rapid reductive elimination upon reaction with phenolates (PhO(-)), to form aryl-OPh cross-coupling products. Kinetic studies show that the reaction follows a different mechanistic pathway compared to the reaction with phenols. The pH active cyclized pincer-like ligand undergoes an initial amine deprotonation that triggers a faster reactivity at room temperature. A mechanistic proposal for the enhanced reactivity and the role of EPR-detected Cu(II) species will be discussed in detail. This journal is © The Royal Society of Chemistry 2011

Visible-light-driven Photocatalytic N-arylation of Imidazole Derivatives and Arylboronic Acids on Cu/graphene catalyst

PubMed Central

Cui, Yan-Li; Guo, Xiao-Ning; Wang, Ying-Yong; Guo, Xiang-Yun

2015-01-01

N-aryl imidazoles play an important role as structural and functional units in many natural products and biologically active compounds. Herein, we report a photocatalytic route for the C-N cross-coupling reactions over a Cu/graphene catalyst, which can effectively catalyze N-arylation of imidazole and phenylboronic acid, and achieve a turnover frequency of 25.4 h−1 at 25 oC and the irradiation of visible light. The enhanced catalytic activity of the Cu/graphene under the light irradiation results from the localized surface plasmon resonance of copper nanoparticles. The Cu/graphene photocatalyst has a general applicability for photocatalytic C-N, C-O and C-S cross-coupling of arylboronic acids with imidazoles, phenols and thiophenols. This study provides a green photocatalytic route for the production of N-aryl imidazoles. PMID:26189944

Mechanism of action for the cytotoxic effects of the nitric oxide prodrug JS-K in murine erythroleukemia cells.

PubMed

Kaczmarek, Monika Z; Holland, Ryan J; Lavanier, Stephen A; Troxler, Jami A; Fesenkova, Valentyna I; Hanson, Charlotte A; Cmarik, Joan L; Saavedra, Joseph E; Keefer, Larry K; Ruscetti, Sandra K

2014-03-01

The nitric oxide (NO) prodrug JS-K, a promising anti-cancer agent, consists of a diazeniumdiolate group necessary for the release of NO as well as an arylating ring. In this study, we research the mechanism by which JS-K kills a murine erythroleukemia cell line and determine the roles of NO and arylation in the process. Our studies indicate that JS-K inhibits the PI 3-kinase/Akt and MAP kinase pathways. This correlates with the activation of the tumor suppressor FoxO3a and increased expression of various caspases, leading to apoptosis. The arylating capability of JS-K appears to be sufficient for inducing these biological effects. Overall, these data suggest that JS-K kills tumor cells by arylating and inactivating signaling molecules that block the activation of a tumor suppressor. Published by Elsevier Ltd.

Palladium-Catalyzed α-Arylation of Zinc Enolates of Esters: Reaction Conditions and Substrate Scope

PubMed Central

Hama, Takuo; Ge, Shaozhong; Hartwig, John F.

2013-01-01

The intermolecular α-arylation of esters by palladium-catalyzed coupling of aryl bromides with zinc enolates of esters is reported. Reactions of three different types of zinc enolates have been developed. α-Arylation of esters occurs in high yields with isolated Reformatsky reagents, with Reformatsky reagents generated from α-bromo esters and activated zinc, and with zinc enolates generated by quenching lithium enolates of esters with zinc chloride. The use of zinc enolates, instead of alkali metal enolates, greatly expands the scope of the arylation of esters. The reactions occur at room temperature or at 70 °C with bromoarenes containing cyano, nitro, ester, keto, fluoro, enolizable hydrogen, hydroxyl or amino functionality and with bromopyridines. The scope of esters encompasses acyclic acetates, propionates, and isobutyrates, α-alkoxyesters, and lactones. The arylation of zinc enolates of esters was conducted with catalysts bearing the hindered pentaphenylferrocenyl di-tert-butylphosphine (Q-phos) or the highly reactive dimeric Pd(I) complex {[P(t-Bu)3]PdBr}2. PMID:23931445

Thiadiazole derivatives as New Class of β-glucuronidase inhibitors.

PubMed

Salar, Uzma; Taha, Muhammad; Ismail, Nor Hadiani; Khan, Khalid Mohammed; Imran, Syahrul; Perveen, Shahnaz; Wadood, Abdul; Riaz, Muhammad

2016-04-15

Thiadiazole derivatives 1-24 were synthesized via a single step reaction and screened for in vitro β-glucuronidase inhibitory activity. All the synthetic compounds displayed good inhibitory activity in the range of IC50=2.16 ± 0.01-58.06 ± 1.60 μM as compare to standard d-saccharic acid 1,4-lactone (IC50=48.4 ± 1.25 μM). Molecular docking study was conducted in order to establish the structure-activity relationship (SAR) which demonstrated that thiadiazole as well as both aryl moieties (aryl and N-aryl) involved to exhibit the inhibitory potential. All the synthetic compounds were characterized by spectroscopic techniques (1)H, (13)C NMR, and EIMS. Copyright © 2016 Elsevier Ltd. All rights reserved.

Synthesis, structure elucidation, DNA-PK and PI3K and anti-cancer activity of 8- and 6-aryl-substituted-1-3-benzoxazines.

PubMed

Morrison, Rick; Al-Rawi, Jasim M A; Jennings, Ian G; Thompson, Philip E; Angove, Michael J

2016-03-03

The synthesis of 6-aryl, 8- aryl, and 8-aryl-6-chloro-2-morpholino-1,3-benzoxazines with potent activity against PI3K and DNA-PK is described. Synthesis of thirty one analogues was facilitated by an improved synthesis of 3-bromo-2-hydroxybenzoic acid 13 by de-sulphonation of 3-bromo-2-hydroxy-5-sulfobenzoic acid 12 en route to 2-methylthio-substituted-benzoxazine intermediates 17-19. From this series, compound 20k (LTURM34) (dibenzo[b,d]thiophen-4-yl) (IC50 = 0.034 μM) was identified as a specific DNA-PK inhibitor, 170 fold more selective for DNA-PK activity compared to PI3K activity. Other compounds of the series show markedly altered selectivity for various PI3K isoforms including compound 20i (8-(naphthalen-1-yl) a potent and quite selective PI3Kδ inhibitor (IC50 = 0.64 μM). Finally, nine compounds were evaluated and showed antiproliferative activity against an NCI panel of cancer cell lines. Compound 20i (8-(naphthalen-1-yl) showed strong anti-proliferative activity against A498 renal cancer cells that warrants further investigation. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Crucial Role of the Aryl Hydrocarbon Receptor (AhR) in Indoxyl Sulfate-Induced Vascular Inflammation.

PubMed

Ito, Shunsuke; Osaka, Mizuko; Edamatsu, Takeo; Itoh, Yoshiharu; Yoshida, Masayuki

2016-08-01

The aryl hydrocarbon receptor (AhR), a ligand-inducible transcription factor mediating toxic effects of dioxins and uremic toxins, has recently emerged as a pathophysiological regulator of immune-inflammatory conditions. Indoxyl sulfate, a uremic toxin, is associated with cardiovascular disease in patients with chronic kidney disease and has been shown to be a ligand for AhR. The aim of this study was to investigate the potential role of AhR in indoxyl sulfate-induced leukocyte-endothelial interactions. Endothelial cell-specific AhR knockout (eAhR KO) mice were produced by crossing AhR floxed mice with Tie2 Cre mice. Indoxyl sulfate was administered for 2 weeks, followed by injection of TNF-α. Leukocyte recruitment to the femoral artery was assessed by intravital microscopy. Vascular endothelial cells were transfected with siRNA specific to AhR (siAhR) and treated with indoxyl sulfate, followed by stimulation with TNF-α. Indoxyl sulfate dramatically enhanced TNF-α-induced leukocyte recruitment to the vascular wall in control animals but not in eAhR KO mice. In endothelial cells, siAhR significantly reduced indoxyl sulfate-enhanced leukocyte adhesion as well as E-selectin expression, whereas the activation of JNK and nuclear factor-κB was not affected. A luciferase assay revealed that the region between －153 and －146 bps in the E-selectin promoter was responsible for indoxyl sulfate activity via AhR. Mutational analysis of this region revealed that activator protein-1 (AP-1) is responsible for indoxyl sulfate-triggered E-selectin expression via AhR. AhR mediates indoxyl sulfate-enhanced leukocyte-endothelial interactions through AP-1 transcriptional activity, which may constitute a new mechanism of vascular inflammation in patients with renal disease.

The common variant Q192R at the paraoxonase 1 (PON1) gene and its activity are responsible for a portion of the altered antioxidant status in type 2 diabetes.

PubMed

Zargari, Mehryar; Sharafeddin, Fahimeh; Mahrooz, Abdolkarim; Alizadeh, Ahad; Masoumi, Parisa

2016-08-01

In this study, we investigated the effects of paraoxonase 1 (PON1) activities and the variant PON1-Q192R on the ferric reducing ability of plasma (FRAP) and total thiol. In addition, we examined the distribution of genotypes of this variant and the relationship of the genotypes with age in patients with type 2 diabetes (T2D). A total of 115 patients with T2D were enrolled in this study. Paraoxonase activity (PON-para) and arylesterase activity (PON-aryl) were determined using spectrophotometric assays. The distribution of the Q192R genotypes was determined by the double substrate method. The antioxidant status was evaluated by determining FRAP and total thiol. The frequencies of Q and R allozyme were 0.78 and 0.22, respectively. The multivariate analysis identified a significant association between the variables PON1-Q192R (Wilks' λ = 0.85, P = 0.002) and PON-aryl (Wilks' λ = 0.896, P = 0.017), with FRAP and total thiol. The significant difference observed for PON1-Q192R and PON-aryl is primarily due to the changes in FRAP levels (η(2 )= 0.127, P = 0.002 for PON1-Q192R; η(2 )= 0.083, P = 0.011 for PON-aryl). The interaction PON1-Q192R-PON-aryl increased the effect sizes from 8 to 19% for FRAP. Only in R-carrying genotypes, there were significant correlations between both PON-para/HDL (r = -0.574, P < 0.001) and PON-aryl/HDL (r = -0.577, P < 0.001) with age. Our data suggest that the variant PON1-Q192R and PON1 activity, particularly PON-aryl, influenced the antioxidant status in T2D. The interaction of this variant and PON1 activity increased the effect size on the antioxidant capacity. Moreover, the presence of the R allozyme may potentiate the effects of age on susceptibility to cardiovascular diseases in T2D. © 2016 by the Society for Experimental Biology and Medicine.

Aryl-substituted aminobenzimidazoles targeting the hepatitis C virus internal ribosome entry site

PubMed Central

Ding, Kejia; Wang, Annie; Boerneke, Mark A.; Dibrov, Sergey M.; Hermann, Thomas

2014-01-01

We describe the exploration of N1-aryl-substituted benzimidazoles as ligands for the hepatitis C virus (HCV) internal ribosome entry site (IRES) RNA. The design of the compounds was guided by the co-crystal structure of a benzimidazole viral translation inhibitor in complex with the RNA target. Structure-binding activity relationships of aryl-substituted benzimidazole ligands were established that were consistent with the crystal structure of the translation inhibitor complex. PMID:24856063

Nucleophilic addition of nitrogen to aryl cations: mimicking Titan chemistry.

PubMed

Li, Anyin; Jjunju, Fred P M; Cooks, R Graham

2013-11-01

The reactivity of aryl cations toward molecular nitrogen is studied systematically in an ion trap mass spectrometer at 10(2) Pascal of nitrogen, the pressure of the Titan main haze layer. Nucleophilic addition of dinitrogen occurs and the nature of aryl group has a significant influence on the reactivity, through inductive effects and by changing the ground state spin multiplicity. The products of nitrogen activation, aryldiazonium ions, react with typical nitriles, aromatic amines, and alkynes (compounds that are relevant as possible Titan atmosphere constituents) to form covalently bonded heterocyclic products. Theoretical calculations at the level [DFT(B3LYP)/6-311++G(d,p)] indicate that the N2 addition reaction is exothermic for the singlet aryl cations but endothermic for their triplet spin isomers. The -OH and -NH2 substituted aryl ions are calculated to have triplet ground states, which is consistent with their decreased nitrogen addition reactivity. The energy needed for the generation of the aryl cations from their protonated precursors (ca. 340 kJ/mol starting with protonated aniline) is far less than that required to directly activate the nitrogen triple bond (the lowest energy excited state of N2 lies ca. 600 kJ/mol above the ground state). The formation of aza-aromatics via arene ionization and subsequent reactions provide a conceivable route to the genesis of nitrogen-containing organic molecules in the interstellar medium and Titan haze layers.

2-Aryl benzimidazoles: Synthesis, In vitro α-amylase inhibitory activity, and molecular docking study.

PubMed

Adegboye, Akande Akinsola; Khan, Khalid Mohammed; Salar, Uzma; Aboaba, Sherifat Adeyinka; Kanwal; Chigurupati, Sridevi; Fatima, Itrat; Taha, Mohammad; Wadood, Abdul; Mohammad, Jahidul Isalm; Khan, Huma; Perveen, Shahnaz

2018-04-25

Despite of many diverse biological activities exhibited by benzimidazole scaffold, it is rarely explored for the α-amylase inhibitory activity. For that purpose, 2-aryl benzimidazole derivatives 1-45 were synthesized and screened for in vitro α-amylase inhibitory activity. Structures of all synthetic compounds were deduced by various spectroscopic techniques. All compounds revealed inhibition potential with IC 50 values of 1.48 ± 0.38-2.99 ± 0.14 μM, when compared to the standard acarbose (IC 50  = 1.46 ± 0.26 μM). Limited SAR suggested that the variation in the inhibitory activities of the compounds are the result of different substitutions on aryl ring. In order to rationalize the binding interactions of most active compounds with the active site of α-amylase enzyme, in silico study was conducted. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

Antimycobacterial activity of new N(1)-[1-[1-aryl-3-[4-(1H-imidazol-1-yl)phenyl]-3-oxo]propyl]-pyridine-2-carboxamidrazone derivatives.

PubMed

Zampieri, Daniele; Mamolo, Maria Grazia; Vio, Luciano; Romano, Maurizio; Skoko, Nataša; Baralle, Marco; Pau, Valentina; De Logu, Alessandro

2016-07-15

N(1)-[1-[1-aryl-3-[4-(1H-imidazol-1-yl)phenyl]-3-oxo]propyl]-pyridine-2-carboxamidrazone derivatives were design, synthesized and tested for their in vitro antimycobacterial activity. The new compounds showed a moderate antimycobacterial activity against the tested strain of Mycobacterium tuberculosis H37Ra and a significant antimycobacterial activity against several mycobacteria other than tuberculosis strains. Copyright © 2016 Elsevier Ltd. All rights reserved.

Synthesis and biological evaluation of novel dioxa-bicycle C-aryl glucosides as SGLT2 inhibitors.

PubMed

Yan, Qi; Ding, Ning; Li, Yingxia

2016-02-08

A series of novel C-aryl glucosides containing dioxa-bicycle were synthesized and evaluated for inhibition activity against hSGLT2. Among the compounds tested, compound 6a showed moderate SGLT2 inhibition activities at 700 nM. The results could benefit the discovery of new SGLT2 inhibitors. Copyright © 2015 Elsevier Ltd. All rights reserved.

Photoredox activation for the direct β-arylation of ketones and aldehydes.

PubMed

Pirnot, Michael T; Rankic, Danica A; Martin, David B C; MacMillan, David W C

2013-03-29

The direct β-activation of saturated aldehydes and ketones has long been an elusive transformation. We found that photoredox catalysis in combination with organocatalysis can lead to the transient generation of 5π-electron β-enaminyl radicals from ketones and aldehydes that rapidly couple with cyano-substituted aryl rings at the carbonyl β-position. This mode of activation is suitable for a broad range of carbonyl β-functionalization reactions and is amenable to enantioselective catalysis.

Palladium-catalyzed coupling of ammonia with aryl chlorides, bromides, iodides, and sulfonates: a general method for the preparation of primary arylamines.

PubMed

Vo, Giang D; Hartwig, John F

2009-08-12

We report that the complex generated from Pd[P(o-tol)(3)](2) and the alkylbisphosphine CyPF-t-Bu is a highly active and selective catalyst for the coupling of ammonia with aryl chlorides, bromides, iodides, and sulfonates. The couplings of ammonia with this catalyst conducted with a solution of ammonia in dioxane form primary arylamines from a variety of aryl electrophiles in high yields. Catalyst loadings as low as 0.1 mol % were sufficient for reactions of many aryl chlorides and bromides. In the presence of this catalyst, aryl sulfonates also coupled with ammonia for the first time in high yields. A comparison of reactions in the presence of this catalyst versus those in the presence of existing copper and palladium systems revealed a complementary, if not broader, substrate scope. The utility of this method to generate amides, imides, and carbamates is illustrated by a one-pot synthesis of a small library of these carbonyl compounds from aryl bromides and chlorides, ammonia, and acid chlorides or anhydrides. Mechanistic studies show that reactions conducted with the combination of Pd[P(o-tol)(3)](2) and CyPF-t-Bu as catalyst occur with faster rates and higher yields than those conducted with CyPF-t-Bu and palladiun(II) as catalyst precursors because of the low concentration of active catalyst that is generated from the combination of palladium(II), ammonia, and base.

N-Acetylanthranilate Amidase from Arthrobacter nitroguajacolicus Rü61a, an α/β-Hydrolase-Fold Protein Active towards Aryl-Acylamides and -Esters, and Properties of Its Cysteine-Deficient Variant▿ †

PubMed Central

Kolkenbrock, Stephan; Parschat, Katja; Beermann, Bernd; Hinz, Hans-Jürgen; Fetzner, Susanne

2006-01-01

N-acetylanthranilate amidase (Amq), a 32.8-kDa monomeric amide hydrolase, is involved in quinaldine degradation by Arthrobacter nitroguajacolicus Rü61a. Sequence analysis and secondary structure predictions indicated that Amq is related to carboxylesterases and belongs to the α/β-hydrolase-fold superfamily of enzymes; inactivation of (His6-tagged) Amq by phenylmethanesulfonyl fluoride and diethyl pyrocarbonate and replacement of conserved residues suggested a catalytic triad consisting of S155, E235, and H266. Amq is most active towards aryl-acetylamides and aryl-acetylesters. Remarkably, its preference for ring-substituted analogues was different for amides and esters. Among the esters tested, phenylacetate was hydrolyzed with highest catalytic efficiency (kcat/Km = 208 mM−1 s−1), while among the aryl-acetylamides, o-carboxy- or o-nitro-substituted analogues were preferred over p-substituted or unsubstituted compounds. Hydrolysis by His6Amq of primary amides, lactams, N-acetylated amino acids, azocoll, tributyrin, and the acylanilide and urethane pesticides propachlor, propham, carbaryl, and isocarb was not observed; propanil was hydrolyzed with 1% N-acetylanthranilate amidase activity. The catalytic properties of the cysteine-deficient variant His6AmqC22A/C63A markedly differed from those of His6Amq. The replacements effected some changes in Kms of the enzyme and increased kcats for most aryl-acetylesters and some aryl-acetylamides by factors of about three to eight while decreasing kcat for the formyl analogue N-formylanthranilate by several orders of magnitude. Circular dichroism studies indicated that the cysteine-to-alanine replacements resulted in significant change of the overall fold, especially an increase in α-helicity of the cysteine-deficient protein. The conformational changes may also affect the active site and may account for the observed changes in kinetic properties. PMID:17041061

A novel dihydropyridine with 3-aryl meta-hydroxyl substitution blocks L-type calcium channels in rat cardiomyocytes

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

Galvis-Pareja, David; Centro Estudios Moleculares de la Célula; Zapata-Torres, Gerald

2014-08-15

Rationale: Dihydropyridines are widely used for the treatment of several cardiac diseases due to their blocking activity on L-type Ca{sup 2+} channels and their renowned antioxidant properties. Methods: We synthesized six novel dihydropyridine molecules and performed docking studies on the binding site of the L-type Ca{sup 2+} channel. We used biochemical techniques on isolated adult rat cardiomyocytes to assess the efficacy of these molecules on their Ca{sup 2+} channel-blocking activity and antioxidant properties. The Ca{sup 2+} channel-blocking activity was evaluated by confocal microscopy on fluo-3AM loaded cardiomyocytes, as well as using patch clamp experiments. Antioxidant properties were evaluated by flowmore » cytometry using the ROS sensitive dye 1,2,3 DHR. Results: Our docking studies show that a novel compound with 3-OH substitution inserts into the active binding site of the L-type Ca{sup 2+} channel previously described for nitrendipine. In biochemical assays, the novel meta-OH group in the aryl in C4 showed a high blocking effect on L-type Ca{sup 2+} channel as opposed to para-substituted compounds. In the tests we performed, none of the molecules showed antioxidant properties. Conclusions: Only substitutions in C2, C3 and C5 of the aryl ring render dihydropyridine compounds with the capacity of blocking LTCC. Based on our docking studies, we postulate that the antioxidant activity requires a larger group than the meta-OH substitution in C2, C3 or C5 of the dihydropyridine ring. - Highlights: • Dihydropyridine (DHP) molecules are widely used in cardiovascular disease. • DHPs block Ca{sup 2+} entry through LTCC—some DHPs have antioxidant activity as well. • We synthesized 6 new DHPs and tested their Ca{sup 2+} blocking and antioxidant activities. • 3-Aryl meta-hydroxyl substitution strongly increases their Ca{sup 2+} blocking activity. • 3-Aryl meta-hydroxyl substitution did not affect the antioxidant properties.« less

A Structure-Activity Study with Aryl Acylamidases

PubMed Central

Villarreal, David T.; Turco, Ronald F.; Konopka, Allan

1994-01-01

We examined the relationship between chemical structure and biodegradability of acylanilide herbicides by using a set of model compounds. Four bacterial isolates (one gram-negative and three gram-positive) that grew on acetanilide were used. These soil isolates cleaved the amide bond of acetanilide via an aryl acylamidase reaction, producing aniline and the organic acid acetate. A series of acetanilide analogs with alkyl substitutions on the nitrogen atom or the aromatic ring were tested for their ability to induce aryl acylamidase activity and act as substrates for the enzyme. The substrate range, in general, was limited to those analogs not disubstituted in the ortho position of the benzene ring or which did not contain an alkyl group on the nitrogen atom. These same N-substituted compounds did not induce enzyme activity either, whereas the ortho-substituted compounds could in some cases. PMID:16349428

Optimization of Aryl Amides that Extend Survival in Prion-Infected Mice.

PubMed

Giles, Kurt; Berry, David B; Condello, Carlo; Dugger, Brittany N; Li, Zhe; Oehler, Abby; Bhardwaj, Sumita; Elepano, Manuel; Guan, Shenheng; Silber, B Michael; Olson, Steven H; Prusiner, Stanley B

2016-09-01

Developing therapeutics for neurodegenerative diseases (NDs) prevalent in the aging population remains a daunting challenge. With the growing understanding that many NDs progress by conformational self-templating of specific proteins, the prototypical prion diseases offer a platform for ND drug discovery. We evaluated high-throughput screening hits with the aryl amide scaffold and explored the structure-activity relationships around three series differing in their N-aryl core: benzoxazole, benzothiazole, and cyano. Potent anti-prion compounds were advanced to pharmacokinetic studies, and the resulting brain-penetrant leads from each series, together with a related N-aryl piperazine lead, were escalated to long-term dosing and efficacy studies. Compounds from each of the four series doubled the survival of mice infected with a mouse-passaged prion strain. Treatment with aryl amides altered prion strain properties, as evidenced by the distinct patterns of neuropathological deposition of prion protein and associated astrocytic gliosis in the brain; however, none of the aryl amide compounds resulted in drug-resistant prion strains, in contrast to previous studies on compounds with the 2-aminothiazole (2-AMT) scaffold. As seen with 2-AMTs and other effective anti-prion compounds reported to date, the novel aryl amides reported here were ineffective in prolonging the survival of transgenic mice infected with human prions. Most encouraging is our discovery that aryl amides show that the development of drug resistance is not an inevitable consequence of efficacious anti-prion therapeutics. Copyright © 2016 by The American Society for Pharmacology and Experimental Therapeutics.

Optimization of Aryl Amides that Extend Survival in Prion-Infected Mice

PubMed Central

Giles, Kurt; Berry, David B.; Condello, Carlo; Dugger, Brittany N.; Li, Zhe; Oehler, Abby; Bhardwaj, Sumita; Elepano, Manuel; Guan, Shenheng; Silber, B. Michael; Olson, Steven H.

2016-01-01

Developing therapeutics for neurodegenerative diseases (NDs) prevalent in the aging population remains a daunting challenge. With the growing understanding that many NDs progress by conformational self-templating of specific proteins, the prototypical prion diseases offer a platform for ND drug discovery. We evaluated high-throughput screening hits with the aryl amide scaffold and explored the structure–activity relationships around three series differing in their N-aryl core: benzoxazole, benzothiazole, and cyano. Potent anti-prion compounds were advanced to pharmacokinetic studies, and the resulting brain-penetrant leads from each series, together with a related N-aryl piperazine lead, were escalated to long-term dosing and efficacy studies. Compounds from each of the four series doubled the survival of mice infected with a mouse-passaged prion strain. Treatment with aryl amides altered prion strain properties, as evidenced by the distinct patterns of neuropathological deposition of prion protein and associated astrocytic gliosis in the brain; however, none of the aryl amide compounds resulted in drug-resistant prion strains, in contrast to previous studies on compounds with the 2-aminothiazole (2-AMT) scaffold. As seen with 2-AMTs and other effective anti-prion compounds reported to date, the novel aryl amides reported here were ineffective in prolonging the survival of transgenic mice infected with human prions. Most encouraging is our discovery that aryl amides show that the development of drug resistance is not an inevitable consequence of efficacious anti-prion therapeutics. PMID:27317802

Highly selective anti-Prelog synthesis of optically active aryl alcohols by recombinant Escherichia coli expressing stereospecific alcohol dehydrogenase.

PubMed

Li, Ming; Nie, Yao; Mu, Xiao Qing; Zhang, Rongzhen; Xu, Yan

2016-07-03

Biocatalytic asymmetric synthesis has been widely used for preparation of optically active chiral alcohols as the important intermediates and precursors of active pharmaceutical ingredients. However, the available whole-cell system involving anti-Prelog specific alcohol dehydrogenase is yet limited. A recombinant Escherichia coli system expressing anti-Prelog stereospecific alcohol dehydrogenase from Candida parapsilosis was established as a whole-cell system for catalyzing asymmetric reduction of aryl ketones to anti-Prelog configured alcohols. Using 2-hydroxyacetophenone as the substrate, reaction factors including pH, cell status, and substrate concentration had obvious impacts on the outcome of whole-cell biocatalysis, and xylose was found to be an available auxiliary substrate for intracellular cofactor regeneration, by which (S)-1-phenyl-1,2-ethanediol was achieved with an optical purity of 97%e.e. and yield of 89% under the substrate concentration of 5 g/L. Additionally, the feasibility of the recombinant cells toward different aryl ketones was investigated, and most of the corresponding chiral alcohol products were obtained with an optical purity over 95%e.e. Therefore, the whole-cell system involving recombinant stereospecific alcohol dehydrogenase was constructed as an efficient biocatalyst for highly enantioselective anti-Prelog synthesis of optically active aryl alcohols and would be promising in the pharmaceutical industry.

Detection and measurement of the agonistic activities of PCBs and mono-hydroxylated PCBs to the constitutive androstane receptor using a recombinant yeast assay.

PubMed

Kamata, Ryo; Shiraishi, Fujio; Kageyama, Shiho; Nakajima, Daisuke

2015-10-01

Polychlorinated biphenyls (PCBs) are thought to exert their toxicities mainly by binding to the aryl hydrocarbon receptor and by stimulating transcription of various genes, notably metabolizing enzymes including the cytochrome P450 (CYP) 1 family. However, PCBs and their metabolites could have potential to activate other nuclear receptors and subsequent events. We focused on the constitutive androstane receptor (CAR) inducing CYP2B and measured the agonistic activity of PCBs and mono-hydroxylated PCBs (OH-PCBs) to the CAR using yeast cells transduced with the human CAR and its response pathway. Twenty-nine of 34 tested PCBs and 72 of 91 OH-PCBs exhibited CAR agonistic effects. Of 41 OH-PCBs that had the same chlorination patterns as the tested PCBs, 9 had activities more than twice those of their non-hydroxylated analogs. In particular, 2',4',6'-trichlorobiphenyl-4-ol and 2,2',4',6'-tetrachlorobiphenyl-4-ol were 332- and 22-fold more potent than their analogs and were 15 times and 2.8 times, respectively, as active as a reference substance, 4-tert-octylphenol. The activities of 17 of the OH-PCBs were reduced to less than half those of their non-hydroxylated analogs. Four OH-PCBs derived from 3 active PCBs were inactive. However, a consistent relationship between hydroxyl substituent position and activity could not be discerned. Comprehensive evaluation of the toxic potential of PCBs and their hydroxylated metabolites and their concentrations in the environment are required. Copyright © 2015 Elsevier Ltd. All rights reserved.

Subcellular Localization of Rice Leaf Aryl Acylamidase Activity 1

PubMed Central

Gaynor, John J.; Still, Cecil C.

1983-01-01

The intracellular localization of aryl acylamidase (aryl-acylamide amidohydrolase, EC 3.5.1.13) in rice (Oryza sativa L. var Starbonnet) leaves was investigated. The enzyme hydrolyzes and detoxifies the herbicide propanil (3,4-dichloropropionanilide) thereby accounting for immunity of the rice plant to herbicidal action. Fractionation of mesophyll protoplasts by differential centrifugation yielded the highest specific activity of amidase in the crude mitochondrial fraction. Further separation of density gradients of the silica sol Percoll also indicated that this enzyme was mitochondrial. By the use of biochemical markers, the purified mitochondrial fraction was shown to be substantially free of contamination from nuclei, chloroplasts, golgi, and plasma membranes. Subfractionation of the purified mitochondria suggests that this enzyme is located on the outer membrane. PMID:16662987

Mice with Inactivation of Aryl Hydrocarbon Receptor-Interacting Protein (Aip) Display Complete Penetrance of Pituitary Adenomas with Aberrant ARNT Expression

PubMed Central

Raitila, Anniina; Lehtonen, Heli J.; Arola, Johanna; Heliövaara, Elina; Ahlsten, Manuel; Georgitsi, Marianthi; Jalanko, Anu; Paetau, Anders; Aaltonen, Lauri A.; Karhu, Auli

2010-01-01

Mutations in the aryl hydrocarbon receptor-interacting protein (AIP) gene have been shown to predispose to pituitary adenoma predisposition, a condition characterized by growth hormone (GH)-secreting pituitary tumors. To study AIP-mediated tumorigenesis, we generated an Aip mouse model. Heterozygous mice developed normally but were prone to pituitary adenomas, in particular to those secreting GH. A complete loss of AIP was detected in these lesions, and full penetrance was reached at the age of 15 months. No excess of any other tumor type was found. Ki-67 analysis indicated that Aip-deficient tumors have higher proliferation rates compared with Aip-proficient tumors, suggesting a more aggressive disease. Similar to human AIP-deficient pituitary adenomas, immunohistochemical studies showed that expression of aryl hydrocarbon receptor nuclear translocator 1 or 2 (ARNT or ARNT2) protein was lost in the mouse tumors, suggesting that mechanisms of AIP-related tumorigenesis involve aberrant ARNT function. The Aip+/− mouse appears to be an excellent model for the respective human disease phenotype. This model constitutes a tool to further study AIP-associated pituitary tumorigenesis and may be potentially valuable in efforts to develop therapeutic strategies to treat pituitary adenomas. PMID:20709796

Synthesis and evaluation of the NSCLC anti-cancer activity and physical properties of 4-aryl-N-phenylpyrimidin-2-amines.

PubMed

Toviwek, Borvornwat; Suphakun, Praphasri; Choowongkomon, Kiattawee; Hannongbua, Supa; Gleeson, M Paul

2017-10-15

Reported herein are efforts to profile 4-aryl-N-phenylpyrimidin-2-amines in terms of their anti-cancer activity towards non small-cell lung carcinoma (NSCLC) cells. We have synthesized new 4-aryl-N-phenylpyrimidin-2-amines and assessed them in terms of their cytotoxicity (A549, NCI-H187, MCF7, Vero & KB) and physicochemical properties (logD 7.4 and solubility). 13f and 13c demonstrated potent anti-cancer activity in A549 cells (0.2µM), compared to 0.4μM for the NSCLC drug Doxorubicin. 13f also displayed low experimental logD 7.4 (2.9) and the best solubility (∼40μM). Compounds 13b and 13d showed the best balance of A549 anti-cancer activity and selectivity. 13g showed good activity and selectivity comparable with the anti-cancer drug Doxorubicin. Copyright © 2017 Elsevier Ltd. All rights reserved.

Photoredox Activation for the Direct β-Arylation of Ketones and Aldehydes

PubMed Central

Pirnot, Michael T.; Rankic, Danica A.; Martin, David B. C.; MacMillan, David W. C.

2013-01-01

The direct β-activation of saturated aldehydes and ketones has long been an elusive transformation. We found that photoredox catalysis in combination with organocatalysis can lead to the transient generation of 5π-electron β-enaminyl radicals from ketones and aldehydes that rapidly couple with cyano-substituted aryl rings at the carbonyl β-position. This mode of activation is suitable for a broad range of carbonyl β-functionalization reactions and is amenable to enantioselective catalysis. PMID:23539600

Triphenylphosphine as Ligand for Room Temperature Ni(0)-Catalyzed Cross-Coupling Reactions of Aryl Chlorides with Arylboronic Acids

PubMed Central

Tang, Zhen-Yu; Hu, Qiao-Sheng

2008-01-01

Room temperature Ni(0)-catalyzed cross-coupling reactions of deactivated aryl chlorides with arylboronic acids with inexpensive triphenylphosphine (PPh3) as a supporting ligand have been accomplished in good to excellent yields. Air-stable Ni(PPh3)2Cl2 has also been established as catalyst precursor and highly active nickel catalysts were obtained when the reduction of Ni(PPh3)2Cl2 with n-BuLi was carried out in presence of an aryl chloride. PMID:16497011

Silica-Supported Catalyst for Enantioselective Arylation of Aldehydes under Batch and Continuous-Flow Conditions.

PubMed

Watanabe, Satoshi; Nakaya, Naoyuki; Akai, Junichiro; Kanaori, Kenji; Harada, Toshiro

2018-05-04

A silica-supported 3-aryl H 8 -BINOL-derived titanium catalyst exhibited high performance in the enantioselective arylation of aromatic aldehydes using Grignard and organolithium reagents not only under batch conditions but also under continuous-flow conditions. Even with a simple pipet reactor packed with the heterogeneous catalyst, the enantioselective production of chiral diarylmethanols could be achieved through a continuous introduction of aldehydes and mixed titanium reagents generated from the organometallic precursors. The pipet reactor could be used repeatedly in different reactions without appreciable deterioration of the activity.

Quantitative High-Throughput Screening and Confirmation Studies for Identification of Compounds that Activate the Aryl Hydrocarbon Receptor Pathway (SETAC)

EPA Science Inventory

The aryl hydrocarbon receptor (AhR) is a transcription factor that mediates adaptive responses to known environmental pollutants, such as aromatic hydrocarbons, through regulation of Phase I and II xenobiotic metabolizing enzymes as well as important growth and differentiation pa...

Cross-coupling of alkenyl/aryl carboxylates with Grignard reagent via Fe-catalyzed C-O bond activation.

PubMed

Li, Bi-Jie; Xu, Li; Wu, Zhen-Hua; Guan, Bing-Tao; Sun, Chang-Liang; Wang, Bi-Qin; Shi, Zhang-Jie

2009-10-21

Iron-catalyzed cross-coupling of alkenyl/aryl carboxylates with primary alkyl Grignard reagent was described. This reaction brought a new family of electrophiles to iron catalysis. The combination of an inexpensive carboxylate electrophile and an iron catalyst would generate ample advantages.

In vitro function of the aryl hydrocarbon receptor predicts in vivo sensitivity of oviparous vertebrates to dioxin-like compounds

EPA Science Inventory

Differences in sensitivity to dioxin-like compounds (DLCs) among species and taxa presents a major challenge to ecological risk assessments. Activation of the aryl hydrocarbon receptor (AHR) regulates adverse effects associated with exposure to DLCs in vertebrates. Prior investig...

Multimetallic Catalysis Enabled Cross-Coupling of Aryl Bromides with Aryl Triflates

PubMed Central

Ackerman, Laura K.G.; Lovell, Matthew M.

2015-01-01

Transition metal-catalyzed strategies for the formation of new C-C bonds have revolutionized the field of organic chemistry, enabling the efficient synthesis of ligands, materials, and biologically active molecules.1–3 In cases where a single metal fails to promote a selective or efficient transformation, the synergistic cooperation4 of two distinct catalysts – multimetallic catalysis – can be employed instead. Many important reactions rely on multimetallic catalysis,5 including the Wacker oxidation of olefins6–8 and the Sonogashira coupling of alkynes with aryl halides.9–10 However, the application of this strategy, even in recently developed methods11, has largely been limited to the use of metals with distinct reactivities, with only one metal catalyst undergoing an oxidative addition.12 In this manuscript, we demonstrate that cooperativity between two d10 metal catalysts, (bipyridine)nickel and (1,3-bis(diphenylphosphino)propane)palladium, enables a general cross-Ullman reaction.13–15 Our method couples aryl bromides with aryl triflates directly, eliminating the use of arylmetal reagents and avoiding the challenge of differentiating between multiple C–H bonds that is required for many C–H activation methods.16–17 The selectivity does not require an excess of either substrate and originates from the orthogonal activity of the two catalysts and the relative stability of the two arylmetal intermediates. While (dppp)Pd reacts preferentially with aryl triflates to afford a persistent intermediate, (bpy)Ni reacts preferentially with aryl bromides to form a transient, reactive intermediate. Although each catalyst forms less than 5% cross product in isolation, together they are able to achieve up to 94% yield. Our results reveal a new, general method for the synthesis of biaryls, heteroaryls, and dienes, as well as a new mechanism for selective transmetalation between two catalysts. We anticipate that this reaction will simplify the synthesis of pharmaceutical agents, many of which are currently made with pre-formed organometallic reagents,1–3 and lead to the discovery of new multimetallic reactions. PMID:26280337

Kinetic analysis of butyrylcholinesterase-catalyzed hydrolysis of acetanilides.

PubMed

Masson, Patrick; Froment, Marie-Thérèse; Gillon, Emilie; Nachon, Florian; Darvesh, Sultan; Schopfer, Lawrence M

2007-09-01

The aryl-acylamidase (AAA) activity of butyrylcholinesterase (BuChE) has been known for a long time. However, the kinetic mechanism of aryl-acylamide hydrolysis by BuChE has not been investigated. Therefore, the catalytic properties of human BuChE and its peripheral site mutant (D70G) toward neutral and charged aryl-acylamides were determined. Three neutral (o-nitroacetanilide, m-nitroacetanilide, o-nitrophenyltrifluoroacetamide) and one positively charged (3-(acetamido) N,N,N-trimethylanilinium, ATMA) acetanilides were studied. Hydrolysis of ATMA by wild-type and D70G enzymes showed a long transient phase preceding the steady state. The induction phase was characterized by a hysteretic "burst". This reflects the existence of two enzyme states in slow equilibrium with different catalytic properties. Steady-state parameters for hydrolysis of the three acetanilides were compared to catalytic parameters for hydrolysis of esters giving the same acetyl intermediate. Wild-type BuChE showed substrate activation while D70G displayed a Michaelian behavior with ATMA as with positively charged esters. Owing to the low affinity of BuChE for amide substrates, the hydrolysis kinetics of neutral amides was first order. Acylation was the rate-determining step for hydrolysis of aryl-acetylamide substrates. Slow acylation of the enzyme, relative to that by esters may, in part, be due suboptimal fit of the aryl-acylamides in the active center of BuChE. The hypothesis that AAA and esterase active sites of BuChE are non-identical was tested with mutant BuChE. It was found that mutations on the catalytic serine, S198C and S198D, led to complete loss of both activities. The silent variant (FS117) had neither esterase nor AAA activity. Mutation in the peripheral site (D70G) had the same effect on esterase and AAA activities. Echothiophate inhibited both activities identically. It was concluded that the active sites for esterase and AAA activities are identical, i.e. S198. This excludes any other residue present in the gorge for being the catalytic nucleophile pole.

Synthesis and antiviral bioactivities of 2-aryl- or 2-methyl-3-(substituted- benzalamino)-4(3H)-quinazolinone derivatives.

PubMed

Gao, Xingwen; Cai, Xuejian; Yan, Kai; Song, Baoan; Gao, Lili; Chen, Zhuo

2007-12-27

A simple and general method has been developed for the synthesis of various4(3H)-quinazolinone derivatives by the treatment of the appropriate 3-amino-2-aryl-4(3H)-quinazolinone with a substituted benzaldehyde in ethanol. The structures of the compoundswere characterized by elemental analysis, IR, (1)H-NMR and (13)C-NMR spectra. The title 2-aryl- or 2-methyl-3-(substituted-benzalamino)-4(3H)-quinazolinone compounds III-1~III-31 were found to possess moderate to good antiviral activity. Semi-quantitative PCR andReal Time PCR assays were used to ascertain the target of action of compound III-31against TMV. The studies suggest that III-31 possesses antiviral activity due to inductionof up-regulation of PR-1a and PR-5, thereby inhibiting virus proliferation and movementby enhancement of the activity of some defensive enzyme.

Enantioselective remote meta-C-H arylation and alkylation via a chiral transient mediator.

PubMed

Shi, Hang; Herron, Alastair N; Shao, Ying; Shao, Qian; Yu, Jin-Quan

2018-06-18

Enantioselective carbon-hydrogen (C-H) activation reactions by asymmetric metallation could provide new routes for the construction of chiral molecules 1,2 . However, current methods are typically limited to the formation of five- or six-membered metallacycles, thereby preventing the asymmetric functionalization of C-H bonds at positions remote to existing functional groups. Here we report enantioselective remote C-H activation using a catalytic amount of a chiral norbornene as a transient mediator, which relays initial ortho-C-H activation to the meta position. This was used in the enantioselective meta-C-H arylation of benzylamines, as well as the arylation and alkylation of homobenzylamines. The enantioselectivities obtained using the chiral transient mediator are comparable across different classes of substrates containing either neutral σ-donor or anionic coordinating groups. This relay strategy could provide an alternative means to remote chiral induction, one of the most challenging problems in asymmetric catalysis 3,4 .

Increasing human Th17 differentiation through activation of orphan nuclear receptor retinoid acid-related orphan receptor γ (RORγ) by a class of aryl amide compounds.

PubMed

Zhang, Wei; Zhang, Jing; Fang, Leiping; Zhou, Ling; Wang, Shuai; Xiang, Zhijun; Li, Yuan; Wisely, Bruce; Zhang, Guifeng; An, Gang; Wang, Yonghui; Leung, Stewart; Zhong, Zhong

2012-10-01

In a screen for small-molecule inhibitors of retinoid acid-related orphan receptor γ (RORγ), we fortuitously discovered that a class of aryl amide compounds behaved as functional activators of the interleukin 17 (IL-17) reporter in Jurkat cells. Three of these compounds were selected for further analysis and found to activate the IL-17 reporter with potencies of ∼0.1 μM measured by EC₅₀. These compounds were shown to directly bind to RORγ by circular dichroism-based thermal stability experiments. Furthermore, they can enhance an in vitro Th17 differentiation process in human primary T cells. As RORγ remains an orphan nuclear receptor, discovery of these aryl amide compounds as functional agonists will now provide pharmacological tools for us to dissect functions of RORγ and facilitate drug discovery efforts for immune-modulating therapies.

Aryl acylamidase activity of human serum albumin with o-nitrotrifluoroacetanilide as the substrate.

PubMed

Masson, Patrick; Froment, Marie-Thérèse; Darvesh, Sultan; Schopfer, Lawrence M; Lockridge, Oksana

2007-08-01

Albumin is generally regarded as an inert protein with no enzyme activity. However, albumin has esterase activity as well as aryl acylamidase activity. A new acetanilide substrate, o-nitrotrifluoroacetanilide (o-NTFNAC), which is more reactive than the classical o-nitroacetanilide, made it possible to determine the catalytic parameters for hydrolysis by fatty-acid free human serum albumin. Owing to the low enzymatic activity of albumin, kinetic studies were performed at high albumin concentration (0.075 mM). The albumin behavior with this substrate was Michaelis-Menten like. Kinetic analysis was performed according to the formalism used for catalysis at high enzyme concentration. This approach provided values for the turnover and dissociation constant of the albumin-substrate complex: k(cat) = 0.13 +/- 0.02 min(-1) and Ks = 0.67 +/- 0.04 mM. MALDI-TOF experiments showed that unlike the ester substrate p-nitrophenyl acetate, o-NTFNAC does not form a stable adduct (acetylated enzyme). Kinetic analysis and MALDI-TOF experiments demonstrated that hydrolysis of o-NTFNAC by albumin is fully rate-limited by the acylation step (k(cat) = k2). Though the aryl acylamidase activity of albumin is low (k(cat)/Ks = 195 M(-1)min(-1)), because of its high concentration in human plasma (0.6-1 mM), albumin may participate in hydrolysis of aryl acylamides through second-order kinetics. This suggests that albumin may have a role in the metabolism of endogenous and exogenous aromatic amides, including drugs and xenobiotics.

Deciphering the Origin, Evolution, and Physiological Function of the Subtelomeric Aryl-Alcohol Dehydrogenase Gene Family in the Yeast Saccharomyces cerevisiae.

PubMed

Yang, Dong-Dong; de Billerbeck, Gustavo M; Zhang, Jin-Jing; Rosenzweig, Frank; Francois, Jean-Marie

2018-01-01

Homology searches indicate that Saccharomyces cerevisiae strain BY4741 contains seven redundant genes that encode putative aryl-alcohol dehydrogenases (AAD). Yeast AAD genes are located in subtelomeric regions of different chromosomes, and their functional role(s) remain enigmatic. Here, we show that two of these genes, AAD4 and AAD14 , encode functional enzymes that reduce aliphatic and aryl-aldehydes concomitant with the oxidation of cofactor NADPH, and that Aad4p and Aad14p exhibit different substrate preference patterns. Other yeast AAD genes are undergoing pseudogenization. The 5' sequence of AAD15 has been deleted from the genome. Repair of an AAD3 missense mutation at the catalytically essential Tyr 73 residue did not result in a functional enzyme. However, ancestral-state reconstruction by fusing Aad6 with Aad16 and by N-terminal repair of Aad10 restores NADPH-dependent aryl-alcohol dehydrogenase activities. Phylogenetic analysis indicates that AAD genes are narrowly distributed in wood-saprophyte fungi and in yeast that occupy lignocellulosic niches. Because yeast AAD genes exhibit activity on veratraldehyde, cinnamaldehyde, and vanillin, they could serve to detoxify aryl-aldehydes released during lignin degradation. However, none of these compounds induce yeast AAD gene expression, and Aad activities do not relieve aryl-aldehyde growth inhibition. Our data suggest an ancestral role for AAD genes in lignin degradation that is degenerating as a result of yeast's domestication and use in brewing, baking, and other industrial applications. IMPORTANCE Functional characterization of hypothetical genes remains one of the chief tasks of the postgenomic era. Although the first Saccharomyces cerevisiae genome sequence was published over 20 years ago, 22% of its estimated 6,603 open reading frames (ORFs) remain unverified. One outstanding example of this category of genes is the enigmatic seven-member AAD family. Here, we demonstrate that proteins encoded by two members of this family exhibit aliphatic and aryl-aldehyde reductase activity, and further that such activity can be recovered from pseudogenized AAD genes via ancestral-state reconstruction. The phylogeny of yeast AAD genes suggests that these proteins may have played an important ancestral role in detoxifying aromatic aldehydes in ligninolytic fungi. However, in yeast adapted to niches rich in sugars, AAD genes become subject to mutational erosion. Our findings shed new light on the selective pressures and molecular mechanisms by which genes undergo pseudogenization. Copyright © 2017 Yang et al.

Deciphering the Origin, Evolution, and Physiological Function of the Subtelomeric Aryl-Alcohol Dehydrogenase Gene Family in the Yeast Saccharomyces cerevisiae

PubMed Central

de Billerbeck, Gustavo M.; Zhang, Jin-jing; Rosenzweig, Frank

2017-01-01

ABSTRACT Homology searches indicate that Saccharomyces cerevisiae strain BY4741 contains seven redundant genes that encode putative aryl-alcohol dehydrogenases (AAD). Yeast AAD genes are located in subtelomeric regions of different chromosomes, and their functional role(s) remain enigmatic. Here, we show that two of these genes, AAD4 and AAD14, encode functional enzymes that reduce aliphatic and aryl-aldehydes concomitant with the oxidation of cofactor NADPH, and that Aad4p and Aad14p exhibit different substrate preference patterns. Other yeast AAD genes are undergoing pseudogenization. The 5′ sequence of AAD15 has been deleted from the genome. Repair of an AAD3 missense mutation at the catalytically essential Tyr73 residue did not result in a functional enzyme. However, ancestral-state reconstruction by fusing Aad6 with Aad16 and by N-terminal repair of Aad10 restores NADPH-dependent aryl-alcohol dehydrogenase activities. Phylogenetic analysis indicates that AAD genes are narrowly distributed in wood-saprophyte fungi and in yeast that occupy lignocellulosic niches. Because yeast AAD genes exhibit activity on veratraldehyde, cinnamaldehyde, and vanillin, they could serve to detoxify aryl-aldehydes released during lignin degradation. However, none of these compounds induce yeast AAD gene expression, and Aad activities do not relieve aryl-aldehyde growth inhibition. Our data suggest an ancestral role for AAD genes in lignin degradation that is degenerating as a result of yeast's domestication and use in brewing, baking, and other industrial applications. IMPORTANCE Functional characterization of hypothetical genes remains one of the chief tasks of the postgenomic era. Although the first Saccharomyces cerevisiae genome sequence was published over 20 years ago, 22% of its estimated 6,603 open reading frames (ORFs) remain unverified. One outstanding example of this category of genes is the enigmatic seven-member AAD family. Here, we demonstrate that proteins encoded by two members of this family exhibit aliphatic and aryl-aldehyde reductase activity, and further that such activity can be recovered from pseudogenized AAD genes via ancestral-state reconstruction. The phylogeny of yeast AAD genes suggests that these proteins may have played an important ancestral role in detoxifying aromatic aldehydes in ligninolytic fungi. However, in yeast adapted to niches rich in sugars, AAD genes become subject to mutational erosion. Our findings shed new light on the selective pressures and molecular mechanisms by which genes undergo pseudogenization. PMID:29079624

Induction of hepatic aryl hydrocarbon hydroxylase and epoxide hydrase in Wistar rats pretreated with oral methadone hydrochloride.

PubMed

Bellward, G D; Gontovnick, L S; Otten, M

1977-01-01

Methadone-HCl added to the drinking water of adult female Wistar rats for 4 weeks produced an increase in the aryl hydrocarbon hydroxylase activity of the hepatic microsomal fraction to 222% of control levels. No change was seen in epoxide hydrase activity. In contrast, when male rats were treated similarly, there was an increase in epoxide hydrase activity to 212% of controls with no change in aryl hydrocarbon hydroxylase activity. No such changes were observed when the subcutaneous route of administration or chronic, low-dose, intraperitoneal injections were used. There were no differences in hepatic cytochrome P-450 or protein concentrations in treated animals as compared to their respective control groups. Control studies were carried out with quinine sulfate in the drinking water to decrease water intake to the level of the methadone-treated group. No elevation in either enzyme activity occurred in this control group. Similarly, paired-feeding studies showed the elevation of enzyme activity to be due to the methadone, not food deprivation. The effects of concurrent therapy of methadone with phenobarbital sodium or 3-methylcholanthrene were compared.

Explorations of Substituted Urea Functionality for Discovery of New Activators of the Heme Regulated Inhibitor Kinase

PubMed Central

Chen, Ting; Takrouri, Khuloud; Hee-Hwang, Sung; Rana, Sandeep; Yefidoff-Freedman, Revital; Halperin, Jose; Natarajan, Amarnath; Morisseau, Christophe; Hammock, Bruce; Chorev, Michael; Aktas, Bertal H.

2014-01-01

Heme-regulated inhibitor kinase (HRI), an eukaryotic translation initiation factor 2 alpha (eIF2α) kinase, plays critical roles in cell proliferation, differentiation, and adaptation to cytoplasmic stress. HRI is also a critical modifier of hemoglobin disorders such as β-thalassemia. We previously identified N,N′-diarylureas as potent activators of HRI suitable for studying biology of this important kinase. To expand the repertoire of chemotypes that activate HRI we screened a ~1,900 member N,N′-disubstituted urea library in the surrogate eIF2α phosphorylation assay identifying N-aryl,N′-cyclohexylphenoxyurea as a promising scaffold. We validated hit compounds as a bona-fide HRI activators in secondary assays and explored contributions of substitutions on the N-aryl and N′-cyclohexylphenoxy groups to their activity by studying focused libraries of complementing analogs. We tested these N-aryl,N′-cyclohexylphenoxyureas in the surrogate eIF2α phosphorylation and cell proliferation assays, demonstrating significantly improved bioactivities and specificities. We consider these compounds to represent lead candidates for the development of potent and specific HRI activators. PMID:24261904

An Evolutionarily Conserved Role for the Aryl Hydrocarbon Receptor in the Regulation of Movement

PubMed Central

Williams, Evan G.; Mouchiroud, Laurent; Frochaux, Michael; Pandey, Ashutosh; Andreux, Pénélope A.; Deplancke, Bart; Auwerx, Johan

2014-01-01

The BXD genetic reference population is a recombinant inbred panel descended from crosses between the C57BL/6 (B6) and DBA/2 (D2) strains of mice, which segregate for about 5 million sequence variants. Recently, some of these variants have been established with effects on general metabolic phenotypes such as glucose response and bone strength. Here we phenotype 43 BXD strains and observe they have large variation (∼5-fold) in their spontaneous activity during waking hours. QTL analyses indicate that ∼40% of this variance is attributable to a narrow locus containing the aryl hydrocarbon receptor (Ahr), a basic helix-loop-helix transcription factor with well-established roles in development and xenobiotic metabolism. Strains with the D2 allele of Ahr have reduced gene expression compared to those with the B6 allele, and have significantly higher spontaneous activity. This effect was also observed in B6 mice with a congenic D2 Ahr interval, and in B6 mice with a humanized AHR allele which, like the D2 allele, is expressed much less and has less enzymatic activity than the B6 allele. Ahr is highly conserved in invertebrates, and strikingly inhibition of its orthologs in D. melanogaster and C. elegans (spineless and ahr-1) leads to marked increases in basal activity. In mammals, Ahr has numerous ligands, but most are either non-selective (e.g. resveratrol) or highly toxic (e.g., 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)). Thus, we chose to examine a major environmental influence—long term feeding with high fat diet (HFD)—to see if the effects of Ahr are dependent on major metabolic differences. Interestingly, while HFD robustly halved movement across all strains, the QTL position and effects of Ahr remained unchanged, indicating that the effects are independent. The highly consistent effects of Ahr on movement indicate that changes in its constitutive activity have a role on spontaneous movement and may influence human behavior. PMID:25255223

Screening a mouse liver gene expression Compendium Identifies Effectors of the Aryl Hydrocarbon receptor (AhR)

EPA Science Inventory

The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor that mediates the biological and toxic effects of 2,3, 7 ,8-tetrachlorodibenzo-p-dioxin {TCDD), dioxin-like compounds (DLC) as well as some drugs and endogenous tryptophan metabolites. Short-term act...

Synthesis and antihyperlipaemic activity of some 2-aminomethyl-3-aryl-5,6,7,8-tetrahydrobenzo(b)/5,6-dimethylthieno++ +(2,3- d) -pyrimidin-4-ones.

PubMed

Gadad, A K; Kapsi, S G; Anegundi, R I; Pattan, S R; Mahajanshetti, C S; Shishoo, C J

1996-10-01

A series of 2-aminomethyl-3-aryl-5,6,7,8-tetrahydrobenzo(b)/5,6-dimethylthieno (2,3-d) pyrimidin-4-ones (IX) were prepared by the displacement reaction between various amines and 2-chloromethyl-3-aryl-5,6, 7,8-tetrahydrobenzo(b)/5, 6-dimethylthieno(2, 3-d) pyrimidin-4-ones (VIII), which are obtained by the cyclization of corresponding chloroacetylamino derivatives (VII) under acidic condition. Compounds VII were obtained by the interaction of VI and chloroacetylchloride in glacial acetic acid. Compounds VIII were converted to corresponding 2-acetoxymethyl derivatives (X) with potassium acetate in glacial acetic acid. Selected compounds were screened for antihyperlipaemic activity in albino rats, whereby most of these compounds were found to be active. The serum cholesterol and triglyceride lowering activities exhibited by compounds 1 and 3 were found to be comparable to that of gemfibrozil. Compounds 1 and 3 were also found to be safe as indicated by their acute toxicity study.

Carbon Dioxide-Mediated C(sp3)-H Arylation of Amine Substrates.

PubMed

Kapoor, Mohit; Liu, Daniel; Young, Michael C

2018-05-25

Elaborating amines via C-H functionalization has been an important area of research over the past decade but has generally relied on an added directing group or sterically hindered amine approach. Since free-amine-directed C(sp 3 )-H activation is still primarily limited to cyclization reactions and to improve the sustainability and reaction scope of amine-based C-H activation, we present a strategy using CO 2 in the form of dry ice that facilitates intermolecular C-H arylation. This methodology has been used to enable an operationally simple procedure whereby 1° and 2° aliphatic amines can be arylated selectively at their γ-C-H positions. In addition to potentially serving as a directing group, CO 2 has also been demonstrated to curtail the oxidation of sensitive amine substrates.

The Guareschi Pyridine Scaffold as a Valuable Platform for the Identification of Selective PI3K Inhibitors.

PubMed

Galli, Ubaldina; Ciraolo, Elisa; Massarotti, Alberto; Margaria, Jean Piero; Sorba, Giovanni; Hirsch, Emilio; Tron, Gian Cesare

2015-09-18

A novel series of 4-aryl-3-cyano-2-(3-hydroxyphenyl)-6-morpholino-pyridines have been designed as potential phosphatidylinositol-3-kinase (PI3K) inhibitors. The compounds have been synthesized using the Guareschi reaction to prepare the key 4-aryl-3-cyano-2,6-dihydroxypyridine intermediate. A different selectivity according to the nature of the aryl group has been observed. Compound 9b is a selective inhibitor against the PI3Kα isoform, maintaining a good inhibitory activity. Docking studies were also performed in order to rationalize its profile of selectivity.

Catalytic Arylation and Vinylation Reactions Directed by Anionic Oxygen Functions via Cleavage of C - H and C - C Bonds

NASA Astrophysics Data System (ADS)

Satoh, Tetsuya; Miura, Masahiro

Aromatic compounds having oxygen-containing substituents such as phenols, phenyl ketones, benzyl alcohols, and benzoic acids undergo regioselective arylation and vinylation via C-H bond cleavage in the presence of transition-metal catalysts. The latter two substrates are also arylated and vinylated via C-C bond cleavage accompanied by liberation of ketones and CO2, respectively. Coordination of their anionic oxygen to the metal center is the key to activate the inert bonds effectively and regioselectively. The recent progress of these oxygen-directed reactions is summarized herein.

Natrolite zeolite supported copper nanoparticles as an efficient heterogeneous catalyst for the 1,3-diploar cycloaddition and cyanation of aryl iodides under ligand-free conditions.

PubMed

Nasrollahzadeh, Mahmoud; Sajadi, S Mohammad; Rostami-Vartooni, Akbar; Khalaj, Mehdi

2015-09-01

In this paper, we report the preparation of Natrolite zeolite supported copper nanoparticles as a heterogeneous catalyst for 1,3-diploar cycloaddition and synthesis aryl nitriles from aryl iodides under ligand-free conditions. The catalyst was characterized using XRD, SEM, TEM, EDS and TG-DTA. The experimental procedure is simple, the products are formed in high yields and the catalyst can be recycled and reused several times without any significant loss of catalytic activity. Copyright © 2015 Elsevier Inc. All rights reserved.

Simple and Efficient Generation of Aryl Radicals from Aryl Triflates: Synthesis of Aryl Boronates and Aryl Iodides at Room Temperature.

PubMed

Liu, Wenbo; Yang, Xiaobo; Gao, Yang; Li, Chao-Jun

2017-06-28

Despite the wide use of aryl radicals in organic synthesis, current methods to prepare them from aryl halides, carboxylic acids, boronic acids, and diazonium salts suffer from limitations. Aryl triflates, easily obtained from phenols, are promising aryl radical progenitors but remain elusive in this regard. Inspired by the single electron transfer process for aryl halides to access aryl radicals, we developed a simple and efficient protocol to convert aryl triflates to aryl radicals. Our success lies in exploiting sodium iodide as the soft electron donor assisted by light. This strategy enables the scalable synthesis of two types of important organic molecules, i.e., aryl boronates and aryl iodides, in good to high yields, with broad functional group compatibility in a transition-metal-free manner at room temperature. This protocol is anticipated to find potential applications in other aryl-radical-involved reactions by using aryl triflates as aryl radical precursors.

A facile iodine(III)-mediated synthesis of 3-(3-aryl-1-phenyl-1H-pyrazol-4-yl)-[1,2,4]triazolo[4,3-a]pyridines via oxidation of 2-((3-aryl-1-phenyl-1H-pyrazol-4-yl)methylene)-1-(pyridin-2-yl)hydrazines and their antimicrobial evaluations

PubMed Central

2011-01-01

Background Fused heterocyclic 1,2,4-triazoles have acquired much importance because of their interesting biological properties. Although a number of methods have been reported in the literature which includes oxidation with phosphorus oxychloride, lead tetraacetate, bromine, etc., hypervalent iodine reagents have emerged as reagents of choice for various synthetically useful transformations due to their low toxicity, ready availability and ease of handling. Results A series of new 3-(3-aryl-1-phenyl-1H-pyrazol-4-yl)-[1,2,4]triazolo[4,3-a]pyridines 4 has been conveniently synthesized by oxidative cyclization of 2-(3-aryl-1-phenyl-1H-pyrazol-4-yl)methylene)-1-(pyridin-2-yl)hydrazines 3 promoted with iodobenzene diacetate under mild conditions (up to 90% isolated yields). All the new compounds were tested in vitro for their antimicrobial activity. Conclusions Iodine(III)-mediated oxidative approach has offered an easy access to new 3-(3-aryl-1-phenyl-1H-pyrazol-4-yl)-[1,2,4]triazolo[4,3-a]pyridines 4. The antibacterial and antifungal activities of newly synthesized compounds have proved them potent antimicrobial agents. PMID:22373059

Structural optimization of N1-aryl-benzimidazoles for the discovery of new non-nucleoside reverse transcriptase inhibitors active against wild-type and mutant HIV-1 strains.

PubMed

Monforte, Anna Maria; De Luca, Laura; Buemi, Maria Rosa; Agharbaoui, Fatima E; Pannecouque, Christophe; Ferro, Stefania

2018-02-01

Non-nucleoside reverse transcriptase inhibitors (NNRTIs) are recommended components of preferred combination antiretroviral therapies used for the treatment of human immunodeficiency virus (HIV) infection. These regimens are extremely effective in suppressing virus replication. Recently, our research group identified some N 1 -aryl-2-arylthioacetamido-benzimidazoles as a novel class of NNRTIs. In this research work we report the design, the synthesis and the structure-activity relationship studies of new compounds (20-34) in which some structural modifications have been introduced in order to investigate their effects on reverse transcriptase (RT) inhibition and to better define the features needed to increase the antiviral activity. Most of the new compounds proved to be highly effective in inhibiting both RT enzyme at nanomolar concentrations and HIV-1 replication in MT4 cells with minimal cytotoxicity. Among them, the most promising N 1 -aryl-2-arylthioacetamido-benzimidazoles and N 1 -aryl-2-aryloxyacetamido-benzimidazoles were also tested toward a panel of single- and double-mutants strain responsible for resistance to NNRTIs, showing in vitro antiviral activity toward single mutants L100I, K103N, Y181C, Y188L and E138K. The best results were observed for derivatives 29 and 33 active also against the double mutants F227L and V106A. Computational approaches were applied in order to rationalize the potency of the new synthesized inhibitors. Copyright © 2017 Elsevier Ltd. All rights reserved.

Microbiome-Derived Tryptophan Metabolites and Their Aryl Hydrocarbon Receptor-Dependent Agonist and Antagonist Activities

PubMed Central

Jin, Un-Ho; Lee, Syng-Ook; Sridharan, Gautham; Lee, Kyongbum; Davidson, Laurie A.; Jayaraman, Arul; Chapkin, Robert S.; Alaniz, Robert

2014-01-01

The tryptophan metabolites indole, indole-3-acetate, and tryptamine were identified in mouse cecal extracts and fecal pellets by mass spectrometry. The aryl hydrocarbon receptor (AHR) agonist and antagonist activities of these microbiota-derived compounds were investigated in CaCo-2 intestinal cells as a model for understanding their interactions with colonic tissue, which is highly aryl hydrocarbon (Ah)–responsive. Activation of Ah-responsive genes demonstrated that tryptamine and indole 3-acetate were AHR agonists, whereas indole was an AHR antagonist that inhibited TCDD (2,3,7,8-tetrachlorodibenzo-p-dioxin)–induced CYP1A1 expression. In contrast, the tryptophan metabolites exhibited minimal anti-inflammatory activities, whereas TCDD decreased phorbol ester-induced CXCR4 [chemokine (C-X-C motif) receptor 4] gene expression, and this response was AHR dependent. These results demonstrate that the tryptophan metabolites indole, tryptamine, and indole-3-acetate modulate AHR-mediated responses in CaCo-2 cells, and concentrations of indole that exhibit AHR antagonist activity (100–250 μM) are detected in the intestinal microbiome. PMID:24563545

Expression, function and regulation of mouse cytochrome P450 enzymes: comparison with human P450 enzymes.

PubMed

Hrycay, E G; Bandiera, S M

2009-12-01

The present review focuses on the expression, function and regulation of mouse cytochrome P450 (Cyp) enzymes. Information compiled for mouse Cyp enzymes is compared with data collected for human CYP enzymes. To date, approximately 40 pairs of orthologous mouse-human CYP genes have been identified that encode enzymes performing similar metabolic functions. Recent knowledge concerning the tissue expression of mouse Cyp enzymes from families 1 to 51 is summarized. The catalytic activities of microsomal, mitochondrial and recombinant mouse Cyp enzymes are discussed and their involvement in the metabolism of exogenous and endogenous compounds is highlighted. The role of nuclear receptors, such as the aryl hydrocarbon receptor, constitutive androstane receptor and pregnane X receptor, in regulating the expression of mouse Cyp enzymes is examined. Targeted disruption of selected Cyp genes has generated numerous Cyp null mouse lines used to decipher the role of Cyp enzymes in metabolic, toxicological and biological processes. In conclusion, the laboratory mouse is an indispensable model for exploring human CYP-mediated activities.

Ligand-free, palladium-catalyzed dihydrogen generation from TMDS: dehalogenation of aryl halides on water.

PubMed

Bhattacharjya, Anish; Klumphu, Piyatida; Lipshutz, Bruce H

2015-03-06

A mild and environmentally attractive dehalogenation of functionalized aryl halides has been developed using nanoparticles formed from PdCl2 in the presence of tetramethyldisiloxane (TMDS) on water. The active catalyst and reaction medium can be recycled. This method can also be applied to cascade reactions in a one-pot sequence.

Cationic Cyclizations and Rearrangements Promoted by a Heterogeneous Gold Catalyst

PubMed Central

2015-01-01

A heterogeneous gold catalyst with remarkable activity for promoting the electrophilic reactions of aryl vinyl ketones and aryl dienyl ketones is described. The catalyst is easy to prepare, is robust, and can be recycled. Low loadings are effective for different types of cationic reactions, including Nazarov cyclizations, lactonizations, and [1,2] shifts. PMID:24432741

Synthesis and cytotoxic activity evaluation of some novel 1-(3-(aryl-4,5-dihydroisoxazol-5-yl)methyl)-4-trihalomethyl-1H-pyrimidin-2-ones in human cancer cells.

PubMed

Lobo, Marcio M; Viau, Cassiana M; Dos Santos, Josiane M; Bonacorso, Helio G; Martins, Marcos A P; Amaral, Simone S; Saffi, Jenifer; Zanatta, Nilo

2015-08-28

The synthesis of a series of 14 new 1-(3-(aryl-4,5-dihydroisoxazol-5-yl)methyl)-4-trihalomethyl-1H-pyrimidin-2-ones from the 1,3-dipolar cycloaddition reaction of 1-allyl-4-(trihalomethyl)pyrimidin-2(1H)-ones with aryl nitrile oxides is described. Also, the antiproliferative activity of the title compounds was tested against five human tumoral cell lines: MCF-7 breast cancer cell line, ER+ (estrogen receptor positive); HepG-2 (hepatoma); T-24 (bladder cancer); HCT-116 cell (colorectal carcinoma); and CACO-2. The preliminary results are promising, since three compounds presented IC50 values below 2 μM, as well as moderate to high selectivity. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

2-(Hetero(aryl)methylene)hydrazine-1-carbothioamides as potent urease inhibitors.

PubMed

Saeed, Aamer; Imran, Aqeel; Channar, Pervaiz A; Shahid, Mohammad; Mahmood, Wajahat; Iqbal, Jamshed

2015-02-01

A small series of 2-(hetero(aryl)methylene) hydrazine-1-carbothioamides including two aryl derivatives was synthesized and tested for their inhibitory activity against urease. Compound (E)-2-(Furan-2-ylmethylene) hydrazine-1-carbothioamide (3f), having a furan ring, was the most potent inhibitor of urease with an IC50 value of 0.58 μM. Molecular modeling was carried out through docking the designed compounds into the urease binding site to predict whether these derivatives have analogous binding mode to the urease inhibitors. The study revealed that all of the tested compounds bind with both metal atoms at the active site of the enzyme. The aromatic ring of the compounds forms ionic interactions with the residues, Ala(440), Asp(494), Ala(636), and Met(637). © 2014 John Wiley & Sons A/S.

C-Aryl glucoside SGLT2 inhibitors containing a biphenyl motif as potential anti-diabetic agents.

PubMed

Ding, Yuyang; Mao, Liufeng; Xu, Dengfeng; Xie, Hui; Yang, Ling; Xu, Hongjiang; Geng, Wenjun; Gao, Yong; Xia, Chunguang; Zhang, Xiquan; Meng, Qingyi; Wu, Donghai; Zhao, Junling; Hu, Wenhui

2015-07-15

A series of highly active C-aryl glucoside SGLT2 inhibitors containing a biphenyl motif were designed and synthesized for biological evaluation. Among the compounds tested, compound 16l demonstrated high inhibitory activity against SGLT2 (IC50=1.9 nM) with an excellent pharmacokinetic profile. Further study indicated that the in vivo efficacy of compound 16l was comparable to that of dapagliflozin, suggesting that further development would be worthwhile. Copyright © 2015 Elsevier Ltd. All rights reserved.

Chirality in the absence of rigid stereogenic elements: steric and electronic effects on the configurational stability of C3 symmetric residual tris-aryl phosphanes.

PubMed

Rizzo, Simona; Cirilli, Roberto; Pierini, Marco

2014-10-01

Residual stereoisomers result whenever closed subsets of appropriately substituted interconverting isomers (the residual stereoisomers) are generated from a full set of stereoisomers under the operation of a favored stereomerization mechanism. In the case of the three-bladed propellers, differentiation of the edges of the blades and strict correlation in the motion of the rings are the prerequisites for the existence of residual stereoisomers. In these systems, the two-ring flip mechanism is the lowest energy process. It does not interconvert all possible conformational stereoisomers generated by helicity and the three-blade-hub rotors. In the case of C3 symmetric systems, two noninterconverting subgroups (the residual stereoisomers) are generated, each one constituted of quickly interconverting diastereoisomers. A series of tris-aryl phosphanes, structurally designed for existing as residual enantiomers or diastereoisomers, bearing substituents differing in size and electronic properties on the aryl rings, were synthesized and characterized. The configurational stability of residual phosphanes, evaluated by dynamic (1) H- and (31) P-NMR analysis and by dynamic enantioselective high-performance liquid chromatography (HPLC), was found 10 kcal mol(-1) lower than that shown by the corresponding phosphane-oxides. In accordance with the calculations, an unexpectedly low barrier for phosphorus pyramidal inversion was invoked as responsible for the scarce configurational stability of the residual tris-arylphosphanes. © 2014 Wiley Periodicals, Inc.

Technical aspects of gel-based proteomics designed for elucidating an aryl hydrocarbon receptor complex.

PubMed

Wada, Yoshinao; Nakano, Norihiko

2004-01-01

The identification of proteins by mass spectrometry has revolutionalized the basic method of identifying proteins constituting an intracellular unit or network for certain biological functions. The gel-based strategy following immunoprecipitation was applied to elucidating proteins associated with the aryl hydrocarbon receptor (AhR). Two hundred femtomoles of AhR was recovered from approximately 2 x 10(7) HepG2 cells by immunoprecipitation and was sufficient for identification by peptide mass fingerprinting. Possible candidates for the AhR-associated proteins were also identified. Improvements of the current strategy to increase the overall sensitivity tenfold are required to clarify the AhR complex in full detail. For example, a combination of trypsin and Achromobacter protease I for in-gel digestion allows the number of missed cleavage sites to be set at zero for database searching, thereby reducing random matches and facilitating identification. There is also room for improvement in each step of sample preparation prior to mass spectrometry.

Palladium-catalyzed C-H functionalization of acyldiazomethane and tandem cross-coupling reactions.

PubMed

Ye, Fei; Qu, Shuanglin; Zhou, Lei; Peng, Cheng; Wang, Chengpeng; Cheng, Jiajia; Hossain, Mohammad Lokman; Liu, Yizhou; Zhang, Yan; Wang, Zhi-Xiang; Wang, Jianbo

2015-04-08

Palladium-catalyzed C-H functionalization of acyldiazomethanes with aryl iodides has been developed. This reaction is featured by the retention of the diazo functionality in the transformation, thus constituting a novel method for the introduction of diazo functionality to organic molecules. Consistent with the experimental results, the density functional theory (DFT) calculation indicates that the formation of Pd-carbene species in the catalytic cycle through dinitrogen extrusion from the palladium ethyl diazoacetate (Pd-EDA) complex is less favorable. The reaction instead proceeds through Ag2CO3 assisted deprotonation and subsequently reductive elimination to afford the products with diazo functionality remained. This C-H functionalization transformation can be further combined with the recently evolved palladium-catalyzed cross-coupling reaction of diazo compounds with aryl iodides to develop a tandem coupling process for the synthesis of α,α-diaryl esters. DFT calculation supports the involvement of Pd-carbene as reactive intermediate in the catalytic cycle, which goes through facile carbene migratory insertion with a low energy barrier (3.8 kcal/mol).

Room-temperature chromium(II)-catalyzed direct arylation of pyridines, aryl oxazolines, and imines using arylmagnesium reagents.

PubMed

Kuzmina, Olesya M; Knochel, Paul

2014-10-03

We report a CrCl2-catalyzed oxidative arylation of various pyridines, aryl oxazolines, and aryl imines using aromatic Grignard reagents in the presence of 2,3-dichlorobutane (DCB). Most of the reactions proceed rapidly at 25 °C and do not require any additional ligand. Benzo[h]quinoline, 2-arylpyridine, aryl oxazoline, and imines were successfully arylated in good yields under these conditions. A TMS-substituent was used to prevent double arylation. After oxidative cross-coupling the TMS-group was further converted to a second ortho-aryl substituent. Remarkably, inexpensive aryl N-butylimine derivatives are excellent substrates for this oxidative arylation.

One-pot palladium-catalyzed synthesis of sulfonyl fluorides from aryl bromides† †Electronic supplementary information (ESI) available: Experimental details and supporting characterisation data. See DOI: 10.1039/c6sc03924c Click here for additional data file.

PubMed Central

Davies, Alyn T.; Curto, John M.

2017-01-01

A mild, efficient synthesis of sulfonyl fluorides from aryl and heteroaryl bromides utilizing palladium catalysis is described. The process involves the initial palladium-catalyzed sulfonylation of aryl bromides using DABSO as an SO2 source, followed by in situ treatment of the resultant sulfinate with the electrophilic fluorine source NFSI. This sequence represents the first general method for the sulfonylation of aryl bromides, and offers a practical, one-pot alternative to previously described syntheses of sulfonyl fluorides, allowing rapid access to these biologically important molecules. Excellent functional group tolerance is demonstrated, with the transformation successfully achieved on a number of active pharmaceutical ingredients, and their precursors. The preparation of peptide-derived sulfonyl fluorides is also demonstrated. PMID:28451264

Pd-Metalated Conjugated Nanoporous Polycarbazoles for Additive-Free Cyanation of Aryl Halides: Boosting Catalytic Efficiency through Spatial Modulation

DOE PAGES

Ding, Shunmin; Tian, Chengcheng; Zhu, Xiang; ...

2017-03-23

Transition-metal-catalyzed cyanation of aryl halides is a common route to benzonitriles, which are integral to many industrial procedures. However, traditional homogeneous catalysts for such processes are expensive and suffer poor recyclability, so a heterogeneous analogue is highly desired. A novel spatial modulation approach has been developed in this paper to fabricate a heterogeneous Pd-metalated nanoporous polymer, which catalyzes the cyanation of aryl halides without need for ligands. Finally, the catalyst displays high activity in the synthesis of benzonitriles, including high product yields, excellent stability and recycling, and broad functional-group tolerance.

Direct C-H Arylation Meets Perovskite Solar Cells: Sn-Free Synthesis Shortcut to High Performance Hole-Transporting Materials.

PubMed

Chang, Yu-Chieh; Lee, Kun-Mu; Lai, Chia-Hsin; Liu, Ching-Yuan

2018-03-30

In contrast to the traditional multistep synthesis, we demonstrate herein a two-step synthesis-shortcut to triphenylamine-based hole-transporting materials (HTMs) through sequential direct C-H arylations. These hole-transporting molecules are fabricated in perovskite-based solar cells (PSCs), exhibiting promising efficiencies up to 17.69%, which is comparable to PSCs utilizing the commercially available spiro-OMeTAD as HTM. This is the first report describing the use of step-saving C-H activations/arylations in the facile synthesis of small-molecule HTMs for perovskite solar cells. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Vitamin K3 (menadione)-induced oncosis associated with keratin 8 phosphorylation and histone H3 arylation.

PubMed

Scott, Gary K; Atsriku, Christian; Kaminker, Patrick; Held, Jason; Gibson, Brad; Baldwin, Michael A; Benz, Christopher C

2005-09-01

The vitamin K analog menadione (K3), capable of both redox cycling and arylating nucleophilic substrates by Michael addition, has been extensively studied as a model stress-inducing quinone in both cell culture and animal model systems. Exposure of keratin 8 (k-8) expressing human breast cancer cells (MCF7, T47D, SKBr3) to K3 (50-100 microM) induced rapid, sustained, and site-specific k-8 serine phosphorylation (pSer73) dependent on signaling by a single mitogen activated protein kinase (MAPK) pathway, MEK1/2. Normal nuclear morphology and k-8 immunofluorescence coupled with the lack of DNA laddering or other features of apoptosis indicated that K3-induced cytotoxicity, evident within 4 h of treatment and delayed but not prevented by MEK1/2 inhibition, was due to a form of stress-activated cell death known as oncosis. Independent of MAPK signaling was the progressive appearance of K3-induced cellular fluorescence, principally nuclear in origin and suggested by in vitro fluorimetry to have been caused by K3 thiol arylation. Imaging by UV transillumination of protein gels containing nuclear extracts from K3-treated cells revealed a prominent 17-kDa band shown to be histone H3 by immunoblotting and mass spectrometry (MS). K3 arylation of histones in vitro followed by electrospray ionization-tandem MS analyses identified the unique Cys110 residue within H3, exposed only in the open chromatin of transcriptionally active genes, as a K3 arylation target. These findings delineate new pathways associated with K3-induced stress and suggest a potentially novel role for H3 Cys110 as a nuclear stress sensor.

The Role of Constitutive Androstane Receptor in Oxazaphosphorine-mediated Induction of Drug-metabolizing Enzymes in Human Hepatocytes

PubMed Central

Wang, Duan; Li, Linhao; Fuhrman, Jennifer; Ferguson, Stephen; Wang, Hongbing

2013-01-01

Purpose The objective of this study was to investigate the roles of the constitutive androstane receptor (CAR) in cyclophosphamide (CPA)- and ifosfamide (IFO)-mediated induction of hepatic drug-metabolizing enzymes (DME). Methods Induction of DMEs was evaluated using real-time RT-PCR and Western blotting analysis in human primary hepatocyte (HPH) cultures. Activation of CAR, pregnane X receptor (PXR), and aryl hydrocarbon receptor by CPA and IFO was assessed in cell-based reporter assays in HepG2 cells and/or nuclear translocation assays in HPHs. Results CYP2B6 reporter activity was significantly enhanced by CPA and IFO in HepG2 cells co-transfected with CYP2B6 reporter plasmid and a chemical-responsive human CAR variant (CAR1+A) construct. Real-time RT-PCR and Western blotting analysis in HPHs showed that both CPA and IFO induced the expressions of CYP2B6 and CYP3A4. Notably, treatment of HPHs with CPA but not IFO resulted in significant nuclear accumulation of CAR, which represents the initial step of CAR activation. Further studies in HPHs demonstrated that selective inhibition of PXR by sulforaphane preferentially repressed IFO- over CPA-mediated induction of CYP2B6. Conclusion These results provide novel insights into the differential roles of CAR in the regulation of CPA- and IFO-induced DME expression and potential drug-drug interactions. PMID:21487929

Transition Metal Free C-N Bond Forming Dearomatizations and Aryl C-H Aminations by in Situ Release of a Hydroxylamine-Based Aminating Agent.

PubMed

Farndon, Joshua J; Ma, Xiaofeng; Bower, John F

2017-10-11

We outline a simple protocol that accesses directly unprotected secondary amines by intramolecular C-N bond forming dearomatization or aryl C-H amination. The method is dependent on the generation of a potent electrophilic aminating agent released by in situ deprotection of O-Ts activated N-Boc hydroxylamines.

Discovery of novel 2-aryl-4-benzoyl-imidazoles targeting the colchicines binding site in tubulin as potential anticancer agents

PubMed Central

Chen, Jianjun; Wang, Zhao; Li, Chien-Ming; Lu, Yan; Vaddady, Pavan K.; Meibohm, Bernd; Dalton, James T.; Miller, Duane D.; Li, Wei

2010-01-01

A series of 2-aryl-4-benzoyl-imidazoles (ABI) was synthesized as a result of structural modifications based on the previous set of 2-aryl-imidazole-4-carboxylic amide (AICA) derivatives and 4-substituted methoxylbenzoyl-aryl-thiazoles (SMART). The average IC50 of the most active compound (5da) was 15.7 nM. ABI analogs have substantially improved aqueous solubility (48.9 μg/mL for 5ga vs. 0.909 μg/mL for SMART-1, 0.137 μg/mL for paclitaxel, and 1.04 μg/mL for Combretastatin A4). Mechanism of action studies indicate that the anticancer activity of ABI analogs is through inhibition of tubulin polymerization by interacting with the colchicine binding site. Unlike paclitaxel and colchicine, the ABI compounds were equally potent against multidrug resistant cancer cells and the sensitive parental melanoma cancer cells. In vivo results indicated that 5cb was more effective than DTIC in inhibiting melanoma xenograph tumor growth. Our results suggest that the novel ABI compounds may be developed to effectively treat drug-resistant tumors. PMID:20919720

Lupinalbin A as the most potent estrogen receptor α- and aryl hydrocarbon receptor agonist in Eriosema laurentii de Wild. (Leguminosae).

PubMed

Ateba, Sylvin Benjamin; Njamen, Dieudonné; Medjakovic, Svjetlana; Zehl, Martin; Kaehlig, Hanspeter; Jungbauer, Alois; Krenn, Liselotte

2014-08-09

Eriosema laurentii De Wild. (Leguminosae) is a plant used in Cameroon against infertility and gynecological or menopausal complaints. In our previous report, a methanol extract of its aerial parts was shown to exhibit estrogenic and aryl hydrocarbon receptor agonistic activities in vitro and to prevent menopausal symptoms in ovariectomized Wistar rats. In order to determine the major estrogen receptor α (ERα) agonists in the extract, an activity-guided fractionation was performed using the ERα yeast screen. To check whether the ERα active fractions/compounds also accounted for the aryl hydrocarbon receptor (AhR) agonistic activity of the crude methanol extract, they were further tested on the AhR yeast screen. This study led to the identification of 2'-hydroxygenistein, lupinalbin A and genistein as major estrogenic principles of the extract. 2'-hydroxygenistein and lupinalbin A were, for the first time, also shown to possess an AhR agonistic activity, whereas genistein was not active in this assay. In addition, it was possible to deduce structure-activity relationships. These results suggest that the identified compounds are the major active principles responsible for the estrogenic and AhR agonistic activities of the crude methanol extract of the aerial parts of Eriosema laurentii.

Copper/amino acid catalyzed cross-couplings of aryl and vinyl halides with nucleophiles.

PubMed

Ma, Dawei; Cai, Qian

2008-11-18

Copper-assisted Ullmann-type coupling reactions are valuable transformations for organic synthesis. Researchers have extensively applied these reactions in both academic and industrial settings. However, two important issues, the high reaction temperatures (normally above 150 degrees C) and the stoichiometric amounts of copper necessary, have greatly limited the reaction scope. To solve these problems, we and other groups have recently explored the use of special ligands to promote these coupling reactions. We first showed that the structure of alpha-amino acids can accelerate Cu-assisted Ullmann reactions, leading to the coupling reactions of aryl halides and alpha-amino acids at 80-90 degrees C. In response to these encouraging results, we also discovered that an l-proline ligand facilitated the following transformations: (1) coupling of aryl halides with primary amines, cyclic secondary amines, and N-containing heterocycles at 40-90 degrees C; (2) coupling of aryl halides with sulfinic acid salts at 80-95 degrees C; (3) azidation of aryl halides and vinyl halides with sodium azide at 40-95 degrees C; (4) coupling of aryl halides with activated methylene compounds at 25-50 degrees C. In addition, we found that N,N-dimethylglycine as a ligand facilitated Cu-catalyzed biaryl ether formation at 90 degrees C. Moreover, Sonogashira reactions worked in the absence of palladium and phosphine ligands, forming enamides from vinyl halides and amides at temperatures ranging from ambient temperature up to 80 degrees C. Furthermore, we discovered that an ortho-amide group can accelerate some Ullmann-type reactions. This functional group in combination with other ligand effects allowed for aryl amination or biaryl ether formation at ambient temperature. The coupling between aryl halides and activated methylene compounds even proceeded at -45 degrees C to enantioselectively form a quaternary carbon center. Taking advantage of these results, we developed several novel approaches for the synthesis of pharmaceutically important heterocycles: 1,2-disubstituted benzimidazoles, polysubstituted indoles, N-substituted 1,3-dihydrobenzimidazol-2-ones, and substituted 3-acyl oxindoles. Our results demonstrate that an l-proline or N,N-dimethylglycine ligand can facilitate most typical Ullmann-type reactions, with reactions occurring under relatively mild conditions and using only 2-20 mol % copper catalysts. These conveniently available and inexpensive catalytic systems not only accelerate the reactions but also tolerate many more functional groups. Thus, they should find considerable application in organic synthesis.

Highly enantioselective arylation of aldehydes and ketones using AlArEt(2)(THF) as aryl sources.

PubMed

Zhou, Shuangliu; Wu, Kuo-Hui; Chen, Chien-An; Gau, Han-Mou

2009-05-01

A series of AlArEt(2)(THF) (Ar = Ph (1a), 4-MeC(6)H(4) (1b), 4-MeOC(6)H(4) (1c), 4-Me(3)SiC(6)H(4) (1d), 2-naphthyl (1e)) were synthesized from reactions of AlEt(2)Br(THF) with ArMgBr. In CDCl(3) solution, the (1)H NMR spectra showed that AlArEt(2)(THF) compounds exist as a mixture of four species of formulas of AlAr(x)Et(3-x) (THF) (x = 0, 1, 2, or 3). AlArEt(2)(THF) compounds were found to be superior and atom-economic reagents for asymmetric aryl additions to organic carbonyls. Aryl additions of AlArEt(2)(THF) to aldehydes catalyzed by the titanium(IV) complex of (R)-H(8)-BINOL were efficient with a short reaction time of 1 h, affording aryl addition products as exclusive or main products in high yields and excellent enantioselectivities of up to 98% ee. Although ethyl additions to aldehydes occurred in minor extent, this study demonstrates that increasing the amount of AlArEt(2)(THF) from 1.2 to 1.4 or to 1.6 equiv significantly improved the aryl addition products of up to >99%. On the other hand, asymmetric arylations of AlArEt(2)(THF) to ketones employing a titanium(IV) catalyst of (S)-BINOL produced optically active tertiary alcohols exclusively in excellent enantioselectivities of up to 94% ee.

Small potent ligands to the insulin-regulated aminopeptidase (IRAP)/AT(4) receptor.

PubMed

Axén, Andreas; Andersson, Hanna; Lindeberg, Gunnar; Rönnholm, Harriet; Kortesmaa, Jarkko; Demaegdt, Heidi; Vauquelin, Georges; Karlén, Anders; Hallberg, Mathias

2007-07-01

Angiotensin IV analogs encompassing aromatic scaffolds replacing parts of the backbone of angiotensin IV have been synthesized and evaluated in biological assays. Several of the ligands displayed high affinities to the insulin-regulated aminopeptidase (IRAP)/AT(4) receptor. Displacement of the C-terminal of angiotensin IV with an o-substituted aryl acetic acid derivative delivered the ligand 4, which exhibited the highest binding affinity (K(i) = 1.9 nM). The high affinity of this ligand provides support to the hypothesis that angiotensin IV adopts a gamma-turn in the C-terminal of its bioactive conformation. Ligand (4) inhibits both human IRAP and aminopeptidase N-activity and induces proliferation of adult neural stem cells at low concentrations. Furthermore, ligand 4 is degraded considerably more slowly in membrane preparations than angiotensin IV. Hence, it might constitute a suitable research tool for biological studies of the (IRAP)/AT(4) receptor.

Identification of 1-Aryl-1H-1,2,3-triazoles as Potential New Antiretroviral Agents.

PubMed

Gonzaga, Daniel T G; Souza, Thiago M L; Andrade, Viviane M M; Ferreira, Vitor F; de C da Silva, Fernando

2018-01-01

Low molecular weight 1-Aryl-1H-1,2,3-triazoles are endowed with various types of biological activities, such as against cancer, HIV and bacteria. Despite the existence of six different classes of antiretroviral drugs in clinical use, HIV/AIDS continue to be an on growing public health problem. In the present study, we synthesized and evaluated thirty 1-Aryl-1H-1,2,3-triazoles against HIV replication. The compounds were prepared by Huisgen 1,3-dipolar cycloaddition protocol catalyzed by Cu(I) between aryl azides and propargylic alcohol followed by further esterification and etherification from a nucleophilic substitution with acid chlorides or alkyl bromides in good yields. The compounds were submitted to the inhibition of HIV replication and evaluation of their cytotoxicity. Initially, the compounds were screened at 10 µM and the most active were further evaluated in order to obtain some pharmacological parameters. Thirty molecules were evaluated, six were selected - because they inhibited more than 80% HIV replication. We further showed that two of these compounds are 8-times more potent, and less cytotoxic, than nevirapine, an antiretroviral drug in clinical use. We identified very simple triazoles with promissing antiretroviral activities that led to the development of new drugs against AIDS. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Menthone aryl acid hydrazones: a new class of anticonvulsants.

PubMed

Jain, Jainendra; Kumar, Y; Sinha, Reema; Kumar, Rajeev; Stables, James

2011-01-01

A series of ten compounds (Compounds J(1)-J(10)) of (±) 3-menthone aryl acid hydrazone was synthesized and characterized by thin layer chromatography and spectral analysis. Synthesized compounds were evaluated for anticonvulsant activity after intraperitoneal (i.p) administration to mice by maximal electroshock (MES) and subcutaneous pentylenetetrazole (scPTZ) induced seizure method and minimal clonic seizure test. Minimal motor impairment was also determined for these compounds. Results obtained showed that four compounds out of ten afforded significant protection in the minimal clonic seizure screen at 6 Hz. Compound J(6), 4-Chloro-N-(2-isopropyl-5-methylcyclohexylidene) benzohydrazide was found to be the most active compound with MES ED(50) of 16.1 mg/kg and protective index (pI) of greater than 20, indicating that (±) 3-menthone aryl acid hydrazone possesses better and safer anticonvulsant properties than other reported menthone derivatives viz. menthone Schiff bases, menthone semicarbazides and thiosemicarbazides.

Mechanism-based inactivation of benzo(a)pyrene hydroxylase by aryl acetylenes and aryl olefins

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

Gan, L.S.; Lu, J.Y.L.; Alworth, W.L.

A series of aryl acetylenes and aryl olefins have been examined as substrates and inhibitors of cytochrome P-450 dependent monooxgenases in liver microsomes from 5,6-benzoflavone or phenobarbital pretreated rats. 1-Ethynylpyrene, 3-ethynylperylene, 2-ethynylfluorene, methyl 1-pyrenyl acetylene, cis- and trans-1-(2-bromovinyl)pyrene, and 1-allylpyrene serve as mechanism-based irreversible inactivators (suicide inhibitors) of benzo(a)pyrene hydroxylase, while 1-vinylpyrene and phenyl 1-pyrenyl acetylene do not cause a detectable suicide inhibition of benzo(a)pyrene hydroxylase. The mechanism-based loss of benzo(a)pyrene hydroxylase caused by the aryl acetylenes is not accompanied by a corresponding loss of the P-450 content of the microsomes (suicide destruction). The suicide inhibition by these aryl acetylenesmore » therefore does not involve covalent binding to the heme moiety of the monooxygenase. Nevertheless, in the presence of NADPH, /sup 3/H-labeled 1-ethynylpyrene becomes covalently attached to the cytochrome P-450 protein; the measured stoichiometry of binding is one 1-ethynylpyrene per P-450 heme unit. The authors conclude that the inhibition of benzo(a)pyrene hydroxylase produced by 1-ethynylpyrene may be related to the mechanism of suicide inhibition of P-450 activity by chloramphenicol rather than the mechanism of suicide destruction of P-450 previously described for acetylene and propyne.« less

The evolution of aryl hydrocarbon signaling proteins: diversity of ARNT isoforms among fish species.

PubMed

Powell, W H; Hahn, M E

2000-01-01

The aryl hydrocarbon receptor nuclear translocator (ARNT) mediates aryl hydrocarbon signaling and toxicity by dimerizing with the ligand-activated aryl hydrocarbon receptor (AHR), forming a complex that binds specific DNA elements and alters transcription of target genes. Two genes encode different forms of ARNT in rodents: ARNT1, which is widely expressed, and ARNT2, which exhibits a very restricted expression pattern. In an effort to characterize aryl hydrocarbon signaling mechanisms in fishes, we previously isolated an ARNT cDNA from Fundulus heteroclitus and discovered that this species expresses ARNT2 ubiquitously. This situation differs not only from mammals, but also from rainbow trout, which expresses a divergent ARNT gene that we hypothesized was peculiar to salmonids (rtARNTa/b). In this communication, we examine the ARNT sequences of multiple fish species, including a newly isolated cDNA from scup (Stenotomus chrysops). Our phylogenetic analysis demonstrates that zebrafish ARNT, like the Fundulus protein, is an ARNT2. Contrary to expectations, the scup ARNT is closely related to the rainbow trout protein, demonstrating that the existence of this ARNT isoform predates the divergence of salmonids from the other teleosts. Thus, different species of fish express distinct and highly conserved isoforms of ARNT. The number, type, and expression pattern of ARNT proteins may contribute to interspecies differences in aryl hydrocarbon toxicity, possibly through distinct interactions with additional PAS-family proteins.

Enantioselective synthesis of substituted piperidines by addition of aryl Grignard reagents to pyridine N-oxides.

PubMed

Hussain, Munawar; Banchelin, Thomas Sainte-Luce; Andersson, Hans; Olsson, Roger; Almqvist, Fredrik

2013-01-04

The synthesis of optically active piperidines by enantioselective addition of aryl Grignard reagents to pyridine N-oxides and lithium binolate followed by reduction is reported for the first time. The reaction results in high yields (51-94%) in combination with good ee (54-80%). Some of these products were subsequently recrystallized, affording enhanced optical purities (>99% ee).

Enantioselective Decarboxylative Arylation of α-Amino Acids via the Merger of Photoredox and Nickel Catalysis.

PubMed

Zuo, Zhiwei; Cong, Huan; Li, Wei; Choi, Junwon; Fu, Gregory C; MacMillan, David W C

2016-02-17

An asymmetric decarboxylative Csp(3)-Csp(2) cross-coupling has been achieved via the synergistic merger of photoredox and nickel catalysis. This mild, operationally simple protocol transforms a wide variety of naturally abundant α-amino acids and readily available aryl halides into valuable chiral benzylic amines in high enantiomeric excess, thereby producing motifs found in pharmacologically active agents.

Aryl triolborates: novel reagent for copper-catalyzed N arylation of amines, anilines, and imidazoles.

PubMed

Yu, Xiao-Qiang; Yamamoto, Yasunori; Miyaura, Norio

2008-09-01

The N arylation of primary and secondary aliphatic amines, anilines, and imidazoles with novel potassium aryl triolborates was carried out in the presence of a reoxidant and a catalytic amount of Cu(OAc)(2) (10 mol %). Aryl triolborates were found to be better reagents than aryl boronic acids or potassium aryl trifluoroborates as the former achieved high yields under mild conditions. Coupling of primary and secondary aliphatic amines to give N-aryl amines in excellent yields was performed under oxygen atmosphere. The reactions of anilines and imidazoles to provide N-aryl anilines and N-aryl imidazoles in good yields proceeded smoothly when trimethylamine N-oxide was used as an oxidant.

Synthesis and biological evaluation of novel 5-aryl-4-(5-nitrofuran-2-yl)-pyrimidines as potential anti-bacterial agents.

PubMed

Verbitskiy, Egor V; Baskakova, Svetlana A; Gerasimova, Natal'ya A; Evstigneeva, Natal'ya P; Zil'berberg, Natal'ya V; Kungurov, Nikolay V; Kravchenko, Marionella A; Skornyakov, Sergey N; Pervova, Marina G; Rusinov, Gennady L; Chupakhin, Oleg N; Charushin, Valery N

2017-07-01

A facile two-step synthetic approach to fluorinated and non-fluorinated 5-aryl-4-(5-nitrofuran-2-yl)-pyrimidines from readily available 5-bromo-4-(furan-2-yl)pyrimidine has been developed. All synthesized compounds were screened in vitro for their antibacterial activities against twelve various bacterial strains. It is demonstrated that some of these compounds exhibited significant antibacterial activities against strains Neisseria gonorrhoeae and Staphylococcus aureus, comparable and even higher with that commercial drug Spectinomycin. Copyright © 2017 Elsevier Ltd. All rights reserved.

A robust protocol for directed aryl sulfotransferase evolution toward the carbohydrate building block GlcNAc.

PubMed

Islam, Shohana; Mate, Diana M; Martínez, Ronny; Jakob, Felix; Schwaneberg, Ulrich

2018-05-01

Bacterial aryl sulfotransferases (AST) utilize p-nitrophenylsulfate (pNPS) as a phenolic donor to sulfurylate typically a phenolic acceptor. Interest in aryl sulfotransferases is growing because of their broad variety of acceptors and cost-effective sulfuryl-donors. For instance, aryl sulfotransferase A (ASTA) from Desulfitobacterium hafniense was recently reported to sulfurylate d-glucose. In this study, a directed evolution protocol was developed and validated for aryl sulfotransferase B (ASTB). Thereby the well-known pNPS quantification system was advanced to operate efficiently as a continuous screening system in 96-well MTP format with a true coefficient of variation of 14.3%. A random mutagenesis library (SeSaM library) of ASTB was screened (1,760 clones) to improve sulfurylation of the carbohydrate building block N-acetylglucosamine (GlcNAc). The beneficial variant ASTB-V1 (Val579Asp) showed an up to 3.4-fold increased specific activity toward GlcNAc when compared to ASTB-WT. HPLC- and MS-analysis confirmed ASTB-V1's increased GlcNAc monosulfurylation (2.4-fold increased product formation) representing the validation of the first successful directed evolution round of an AST for a saccharide substrate. © 2017 Wiley Periodicals, Inc.

Activation of aryl hydrocarbon receptor reduces carbendazim-induced cell death

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

Wei, Kuo-Liang

Carbendazim inhibits microtubule assembly, thus blocking mitosis and inhibiting cancer cell proliferation. Accordingly, carbendazim is being explored as an anticancer drug. Data show that carbendazim increased mRNA and protein expressions and promoter activity of CYP1A1. In addition, carbendazim activated transcriptional activity of the aryl hydrocarbon response element, and induced nuclear translocation of the aryl hydrocarbon receptor (AhR), a sign the AhR is activated. Carbendazim-induced CYP1A1 expression was blocked by AhR antagonists, and was abolished in AhR signal-deficient cells. Results demonstrated that carbendazim activated the AhR, thereby stimulating CYP1A1 expression. In order to understand whether AhR-induced metabolic enzymes turn carbendazim intomore » less-toxic metabolites, Hoechst 33342 staining to reveal carbendazim-induced nuclear changes and flow cytometry to reveal the subG{sub 0}/G{sub 1} population were applied to monitor carbendazim-induced cell apoptosis. Carbendazim induced less apoptosis in Hepa-1c1c7 cells than in AhR signal-deficient Hepa-1c1c7 mutant cells. Pretreatment with β-NF, an AhR agonist that highly induces CYP1A1 expression, decreased carbendazim-induced cell death. In addition, the lower the level of AhR was, the lower the vitality present in carbendazim-treated cells, including hepatoma cells and their derivatives with AhR RNA interference, also embryonic kidney cells, bladder carcinoma cells, and AhR signal-deficient Hepa-1c1c7 cells. In summary, carbendazim is an AhR agonist. The toxicity of carbendazim was lower in cells with the AhR signal. This report provides clues indicating that carbendazim is more potent at inducing cell death in tissues without than in those with the AhR signal, an important reference for applying carbendazim in cancer chemotherapy. - Highlights: • Carbendazim induced transcriptional activity of the aryl hydrocarbon response element. • Carbendazim induced nuclear translocation of the aryl hydrocarbon receptor (AhR). • Carbendazim induced the expression of cytochrome P450 (CYP) 1A1, an AhR-targeted gene. • Carbendazim is an AhR agonist. • The activated AhR decreased carbendazim-induced cell toxicity and death.« less

Synthesis of 2-aryl and 3-aryl benzo[b]furan thioethers using aryl sulfonyl hydrazides as sulfenylation reagents.

PubMed

Zhao, Xia; Zhang, Lipeng; Lu, Xiaoyu; Li, Tianjiao; Lu, Kui

2015-03-06

An efficient, metal-free protocol used to synthesize aryl benzo[b]furan thioethers based on the I2-catalyzed cross-coupling of benzo[b]furans as well as the electrophilic cyclization of 2-alkynylphenol derivatives with aryl sulfonyl hydrazides was developed. Various 2-aryl and 3-aryl benzo[b]furan thioethers were obtained in moderate to good yields.

Symmetrical and unsymmetrical pincer complexes with group 10 metals: synthesis via aryl C-H activation and some catalytic applications.

PubMed

Niu, Jun-Long; Hao, Xin-Qi; Gong, Jun-Fang; Song, Mao-Ping

2011-05-21

Aryl-based pincer metal complexes with anionic terdentate ligands have been widely applied in organic synthesis, organometallic catalysis and other related areas. Synthetically, the most simple and convenient method for the construction of these complexes is the direct metal-induced C(aryl)-H bond activation, which can be fulfilled by choosing the appropriate functional donor groups in the two side arms of the aryl-based pincer preligands. In this perspective, we wish to summarize some results achieved by our group in this context. Successful examples include symmetrical chiral bis(imidazoline) NCN pincer complexes with Ni(II), Pd(II) and Pt(II), bis(phosphinite) and bis(phosphoramidite) PCP pincer Pd(II) complexes, unsymmetrical (pyrazolyl)phosphinite, (amino)phosphinite and (imino)phosphinite PCN pincer Pd(II) complexes, chiral (imidazolinyl)phosphinite and (imidazolinyl)phosphoramidite PCN pincer complexes with Ni(II) and Pd(II) as well as unsymmetrical (oxazolinyl)amine and (oxazolinyl)pyrazole NCN' pincer Pd(II) complexes. Among them, the P-donor containing complexes are efficiently synthesized by the "one-pot phosphorylation/metalation" method. The obtained symmetrical and unsymmetrical pincer complexes have been used as catalysts in Suzuki-Miyaura reaction (Pd), asymmetric Friedel-Crafts alkylation of indole with trans-β-nitrostyrene (Pt) as well as in asymmetric allylation of aldehyde and sulfonimine (Pd). In the Suzuki couplings conducted at 40-50 °C, some unsymmetrical Pd complexes exhibit much higher activity than the related symmetrical ones which can be attributed to their faster release of active Pd(0) species resulting from the hemilabile coordination of the ligands. Literature results on the synthesis of some related pincer complexes as well as their activities in the above catalytic reactions are also presented.

Metal-Mediated Halogen Exchange in Aryl and Vinyl Halides: A Review

PubMed Central

Evano, Gwilherm; Nitelet, Antoine; Thilmany, Pierre; Dewez, Damien F.

2018-01-01

Halogenated arenes and alkenes are of prime importance in many areas of science, especially in the pharmaceutical, agrochemical, and chemical industries. While the simplest ones are commercially available, some of them are still hardly accessible depending on their substitution patterns and the nature of the halogen atom. Reactions enabling the selective and efficient replacement of the halogen atom of an aryl or alkenyl halide by another one, lighter, or heavier, are therefore of major importance since they can be used for example to turn a less reactive aryl/alkenyl chloride into the more reactive iodinated derivatives or, in a reversed sense, to block an undesired reactivity, for late-stage modifications or for the introduction of a radionuclide. If some halogen exchange reactions are possible with activated substrates, they usually require catalysis with metal complexes. Remarkably efficient processes have been developed for metal-mediated halogen exchange in aryl and vinyl halides: they are overviewed, in a comprehensive manner, in this review article. PMID:29755967

A new look at acid catalyzed deacetylation of carbohydrates: A regioselective synthesis and reactivity of 2-O-acetyl aryl glycopyranosides.

PubMed

Stepanova, Elena V; Nagornaya, Marina O; Filimonov, Victor D; Valiev, Rashid R; Belyanin, Maxim L; Drozdova, Anna K; Cherepanov, Victor N

2018-03-22

In the present work we report that acetyl groups of per - acetylated aryl glycosides have different reactivity during the acidic deacetylation using HCl/EtOH in CHCl 3, which leads to preferential deacetylation at O-3, O-4 and O-6. Thereby, the one-step preparation of 2-O-acetyl aryl glycosides with simple aglycon was accomplished for the first time. It was proved that the found reagent is to be general and unique for the preparation of series of 2-О-acetyl aryl glycosides. We have determined the influence of both carbohydrate moiety and the aglycon on the selectivity of deacetylation reaction by kinetic experiments. Using DFT/B3LYP/6-31G(d,p) and semi-empirical АМ1 methods we have found that the highest activation barrier is for 2-О-acetyl group. This completely explains the least reactivity of 2-О-acetyl group. Copyright © 2018 Elsevier Ltd. All rights reserved.

Metal-Mediated Halogen Exchange in Aryl and Vinyl Halides: a Review

NASA Astrophysics Data System (ADS)

Evano, Gwilherm; Nitelet, Antoine; Thilmany, Pierre; Dewez, Damien F.

2018-04-01

Halogenated arenes and alkenes are of prime importance in many areas of science, especially in the pharmaceutical, agrochemical and chemical industries. While the simplest ones are commercially available, some of them are still hardly accessible depending on their substitution patterns and the nature of the halogen atom. Reactions enabling the selective and efficient replacement of the halogen atom of an aryl or alkenyl halide by another one, lighter or heavier, are therefore of major importance since they can be used for example to turn a less reactive aryl/alkenyl chloride into the more reactive iodinated derivatives or, in a reversed sense, to block an undesired reactivity, for late-stage modifications or for the introduction of a radionuclide. If some halogen exchange reactions are possible with activated substrates, they usually require catalysis with metal complexes. Remarkably efficient processes have been developed for metal-mediated halogen exchange in aryl and vinyl halides: they are overviewed, in a comprehensive manner, in this review article.

Synthesis and biological evaluation of novel tetrahydroisoquinoline-C-aryl glucosides as SGLT2 inhibitors for the treatment of type 2 diabetes.

PubMed

Pan, Xuan; Huan, Yi; Shen, Zhufang; Liu, Zhanzhu

2016-05-23

A series of novel tetrahydroisoquinoline-C-aryl glucosides has been synthesized and evaluated for the inhibition of human SGLT2. Compared with dapagliflozin, compound 13h exhibited equivalent in vitro inhibitory activity against SGLT2, which might become a promising candidate for the treatment of type 2 diabetes. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

DEVELOPMENTAL EXPRESSION OF TWO MEMBERS OF A NEW CLASS OF TRANSCRIPTION FACTORS: II. EXPRESSION OF ARYL HYDROCARBON RECEPTOR NUCLEAR TRANSLOCATOR IN THE C57BL/6N MOUSE EMBRYO

EPA Science Inventory

The Aryl hydrocarbon receptor (AhR) is a ligand-activated, transcription factor with a basic region/helix (bHLH) motif. hR has been sequenced and the functional domains defined and there is information on the formation of complexes with other peptides and interactions with DNA, a...

Enantioselective Decarboxylative Arylation of α-Amino Acids via the Merger of Photoredox and Nickel Catalysis

PubMed Central

Zuo, Zhiwei; Cong, Huan; Li, Wei; Choi, Junwon; Fu, Gregory C.; MacMillan, David W. C.

2016-01-01

An asymmetric decarboxylative Csp3–Csp2 cross-coupling has been achieved via the synergistic merger of photoredox and nickel catalysis. This mild, operationally simple protocol transforms a wide variety of naturally abundant α-amino acids and readily available aryl halides into valuable chiral benzylic amines in high enantiomeric excess, thereby producing motifs found in pharmacologically active agents. PMID:26849354

Mechanism-based inactivation of cytochrome P-450 dependent benzo(a)pyrene hydroxylase activity by acetylenic and olefinic polycyclic arylhydrocarbons

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

Gan, L.S.

A series of aryl acetylenes and aryl olefins have been examined as substrates and inhibitors of cytochrome P-450 dependent monooxygenases in liver microsomes from 5,6-benzoflavone or phenobarbital pretreated rats. 1-Ethynylpyrene (EP), 3-ethynylperylene (EPL), cis- and trans-1-(2-bromo-vinyl)pyrene (c-BVP and t-BVP), and 1-allylpyrene (AP) serve as mechanism-based irreversible inactivators (suicide inhibitors) of benzo(a)pyrene (BP) hydroxylase, while 1-vinyl-pyrene (VP) and phenyl 1-pyrenyl acetylene (PPA) do not cause a detectable suicide inhibition of the BP hydroxylase. The mechanism-based loss of BP hydroxylase activity caused by the aryl acetylenes is not accompanied by a corresponding loss of the P-450 content of the microsomes. In themore » presence of NADPH, /sup 3/H-labeled EP covalently attached to P-450 isozymes with a measured stoichiometry of one mole of EP per mole of the P-450 heme. The results of the effects of these aryl derivatives in the mammalian cell-mediated mutagenesis assay and toxicity assay show that none of the compounds examined nor any of the their metabolites produced in the incubation system are cytotoxic to V79 cells.« less

Copper Mediated Fluorination of Aryl Iodides

PubMed Central

Fier, Patrick S.; Hartwig, John F.

2012-01-01

The synthesis of aryl fluorides has been a topic of considerable interest because of the importance of aryl fluorides in pharmaceuticals, agrochemicals and materials. The stability, reactivity and biological properties of aryl fluorides can be distinct from those of the corresponding arenes. Methods for the synthesis of aryl fluorides, however, are limited. We report the conversion of a diverse set of aryl iodides to the corresponding aryl fluorides. This reaction occurs with a cationic copper reagent and silver fluoride. Preliminary results suggest this reaction is enabled by a facile reductive elimination from a cationic aryl copper(III) fluoride. PMID:22709145

Conducting polymer for high power ultracapacitor

DOEpatents

Shi, Steven Z.; Gottesfeld, Shimshon

2002-01-01

In accordance with the purposes of the present invention, as embodied and broadly described herein, the present invention is directed to an electrode having a conducting polymer active material for use in an ultracapacitor. The conducting polymer active material is electropolymerized onto a carbon paper substrate from a mixed solution of a dimer of (3,3' bithiophene) (BT) and a monomer that is selected from the group of thiophenes derived in the 3-position, having an aryl group attached to thiophene in the 3-position or having aryl and alkly groups independently attached to thiophene in the 3 and 4 positions.

A convenient catalyst for aqueous and protein Suzuki-Miyaura cross-coupling.

PubMed

Chalker, Justin M; Wood, Charlotte S C; Davis, Benjamin G

2009-11-18

A phosphine-free palladium catalyst for aqueous Suzuki-Miyaura cross-coupling is presented. The catalyst is active enough to mediate hindered, ortho-substituted biaryl couplings but mild enough for use on peptides and proteins. The Suzuki-Miyaura couplings on protein substrates are the first to proceed in useful conversions. Notably, hydrophobic aryl and vinyl groups can be transferred to the protein surface without the aid of organic solvent since the aryl- and vinylboronic acids used in the coupling are water-soluble as borate salts. The convenience and activity of this catalyst prompts use in both general synthesis and bioconjugation.

Synthesis and SAR studies of novel 2-(6-aminomethylaryl-2-aryl-4-oxo-quinazolin-3(4H)-yl)acetamide vasopressin V1b receptor antagonists.

PubMed

Napier, Susan E; Letourneau, Jeffrey J; Ansari, Nasrin; Auld, Douglas S; Baker, James; Best, Stuart; Campbell-Wan, Leigh; Chan, Ray; Craighead, Mark; Desai, Hema; Ho, Koc-Kan; MacSweeney, Cliona; Milne, Rachel; Richard Morphy, J; Neagu, Irina; Ohlmeyer, Michael H J; Pick, Jack; Presland, Jeremy; Riviello, Chris; Zanetakos, Heather A; Zhao, Jiuqiao; Webb, Maria L

2011-06-15

Synthesis and structure-activity relationships (SAR) of a novel series of vasopressin V(1b) antagonists are described. 2-(6-Aminomethylaryl-2-aryl-4-oxo-quinazolin-3(4H)-yl)acetamide have been identified with low nanomolar affinity for the V(1b) receptor and good selectivity with respect to related receptors V(1a), V(2) and OT. Optimised compound 16 shows a good pharmacokinetic profile and activity in a mechanistic model of HPA dysfunction. Copyright © 2011 Elsevier Ltd. All rights reserved.

Efficient synthesis, structural characterization and anti-microbial activity of chiral aryl boronate esters of 1,2-O-isopropylidene-α-D-xylofuranose.

PubMed

Trivedi, Rajiv; Rami Reddy, E; Kiran Kumar, Ch; Sridhar, B; Pranay Kumar, K; Srinivasa Rao, M

2011-07-01

A simple and efficient synthetic approach toward a series of chiral aryl boronate esters, starting from D-xylose, as anti-microbial agents, is described herein. Minimum inhibitory concentration and zone of inhibition revealed that these derivatives exhibit potent anti-bacterial and anti-fungal properties. Herein, we report the first anti-microbial activity of this class of compounds. All products have been characterized by NMR ((1)H, (13)C and (11)B), IR, elemental and mass spectral study. Copyright © 2011 Elsevier Ltd. All rights reserved.

Decarbonylative Phosphorylation of Amides by Palladium and Nickel Catalysis: The Hirao Cross-Coupling of Amide Derivatives.

PubMed

Liu, Chengwei; Szostak, Michal

2017-10-02

Considering the ubiquity of organophosphorus compounds in organic synthesis, pharmaceutical discovery agrochemical crop protection and materials chemistry, new methods for their construction hold particular significance. A conventional method for the synthesis of C-P bonds involves cross-coupling of aryl halides and dialkyl phosphites (the Hirao reaction). We report a catalytic deamidative phosphorylation of a wide range of amides using a palladium or nickel catalyst giving aryl phosphonates in good to excellent yields. The present method tolerates a wide range of functional groups. The reaction constitutes the first example of a transition-metal-catalyzed generation of C-P bonds from amides. This redox-neutral protocol can be combined with site-selective conventional cross-coupling for the regioselective synthesis of potential pharmacophores. Mechanistic studies suggest an oxidative addition/transmetallation pathway. In light of the importance of amides and phosphonates as synthetic intermediates, we envision that this Pd and Ni-catalyzed C-P bond forming method will find broad application. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ruthenium(η⁶,η¹-arene-CH₂-NHC) Catalysts for Direct Arylation of 2-Phenylpyridine with (Hetero)Aryl Chlorides in Water.

PubMed

Kaloğlu, Nazan; Özdemir, İsmail; Gürbüz, Nevin; Arslan, Hakan; Dixneuf, Pierre H

2018-03-13

A series of new benzimidazolium halides were synthesized in good yields as unsymmetrical N -heterocyclic carbene (NHC) precursors containing the N-CH₂-arene group. The benzimidazolium halides were readily converted into ruthenium(II)-NHC complexes with the general formula [RuCl₂(η⁶,η¹-arene-CH₂-NHC)]. The structures of all new compounds were characterized by ¹H NMR (Nuclear Magnetic Resonance), 13 C NMR, FT-IR (Fourier Transform Infrared) spectroscopy and elemental analysis techniques. The single crystal structure of one benzimidazole ruthenium complex, 2b , was determined. The complex is best thought of as containing an octahedrally coordinated Ru center with the arene residue occupying three sites, the remaining sites being occupied by a (carbene)C-Ru bond and two Ru-Cl bonds. The catalytic activity of [RuCl₂(η⁶,η ¹ -arene-CH₂-NHC)] complexes was evaluated in the direct (hetero)arylation of 2-phenylpyridine with (hetero)aryl chlorides in water as the nontoxic reaction medium. These results show that catalysts 2a and 2b were the best for monoarylation with simple phenyl and tolyl chlorides. For functional aryl chlorides, 2d , 2e , and 2c appeared to be the most efficient.

An assessment of antioxidant status in patients with carbon monoxide poisoning

PubMed Central

Zengin, Suat; A, Behcet; Karta, Sahin; Can, Basri; Orkmez, Mustafa; Taskin, Abdullah; Lok, Ugur; Gulen, Bediha; Yildirim, Cuma; Taysi, Seyithan

2014-01-01

BACKGROUND: Carbon monoxide poisoning (COP) is an important cause of mortality and morbidity worldwide. This study was to investigate the levels of serum paraoxonase (PON), arylesterase (ARYL), ceruloplasmin (Cp), and sulfhydryl (-SH) in the treatment of COP, and to further understand the pathophysiology of COP. METHODS: This prospective study comprised 107 individuals with COP (group 1) and 50 healthy volunteers (group 2). Serum, plasma, and erythrocyte samples were taken on admission from all participants with COP. This process was repeated in the 90th and 180th minutes of treatment. Samples were taken from the control group only once. The levels of plasma PON, ARYL, Cp activity and -SH were measured in both groups. RESULTS: Age, gender, and carboxyhemoglobin level were not correlated with PON, ARYL, Cp, and -SH levels. PON, ARYL, and -SH levels were significantly decreased in group 1 compared with group 2. Conversely, Cp was significantly elevated in group 1 in contrast to group 2. Although ARYL was lower on admission in patients with COP than that was observed in the 90th and 180th minutes (P<0.001), Cp was higher on admission than at the other time points (P<0.001). CONCLUSIONS: Participants with COP had decreased levels of antioxidants (PON, ARLY, and -SH). COP represses the antioxidant system. PMID:25215155

Synthesis of substituted isoquinolines utilizing palladium-catalyzed α-arylation of ketones

PubMed Central

Donohoe, Timothy J.; Pilgrim, Ben S.; Jones, Geraint R.; Bassuto, José A.

2012-01-01

The utilization of sequential palladium-catalyzed α-arylation and cyclization reactions provides a general approach to an array of isoquinolines and their corresponding N-oxides. This methodology allows the convergent combination of readily available precursors in a regioselective manner and in excellent overall yields. This powerful route to polysubstituted isoquinolines, which is not limited to electron rich moieties, also allows rapid access to analogues of biologically active compounds. PMID:22753504

Assaying Oxidative Coupling Activity of CYP450 Enzymes.

PubMed

Agarwal, Vinayak

2018-01-01

Cytochrome P450 (CYP450) enzymes are ubiquitous catalysts in natural product biosynthetic schemes where they catalyze numerous different transformations using radical intermediates. In this protocol, we describe procedures to assay the activity of a marine bacterial CYP450 enzyme Bmp7 which catalyzes the oxidative radical coupling of polyhalogenated aromatic substrates. The broad substrate tolerance of Bmp7, together with rearrangements of the aryl radical intermediates leads to a large number of products to be generated by the enzymatic action of Bmp7. The complexity of the product pool generated by Bmp7 thus presents an analytical challenge for structural elucidation. To address this challenge, we describe mass spectrometry-based procedures to provide structural insights into aryl crosslinked products generated by Bmp7, which can complement subsequent spectroscopic experiments. Using the procedures described here, for the first time, we show that Bmp7 can efficiently accept polychlorinated aryl substrates, in addition to the physiological polybrominated substrates for the biosynthesis of polyhalogenated marine natural products. © 2018 Elsevier Inc. All rights reserved.

Pharmacological and structure-activity relationship evaluation of 4-aryl-1-diphenylacetyl(thio)semicarbazides.

PubMed

Wujec, Monika; Kędzierska, Ewa; Kuśmierz, Edyta; Plech, Tomasz; Wróbel, Andrzej; Paneth, Agata; Orzelska, Jolanta; Fidecka, Sylwia; Paneth, Piotr

2014-04-16

This article describes the synthesis of six 4-aryl-(thio)semicarbazides (series a and b) linked with diphenylacetyl moiety along with their pharmacological evaluation on the central nervous system in mice and computational studies, including conformational analysis and electrostatic properties. All thiosemicarbazides (series b) were found to exhibit strong antinociceptive activity in the behavioural model. Among them, compound 1-diphenylacetyl-4-(4-methylphenyl)thiosemicarbazide 1b was found to be the most potent analgesic agent, whose activity is connected with the opioid system. For compounds from series a significant anti-serotonergic effect, especially for compound 1-diphenylacetyl-4-(4-methoxyphenyl)semicarbazide 2b was observed. The computational studies strongly support the obtained results.

Enzymatic hydrolysis of esters containing a tetrazole ring.

PubMed

Łukowska-Chojnacka, Edyta; Mierzejewska, Jolanta

2014-12-01

The lipase-catalyzed enantioselective hydrolysis of acetates containing tetrazole moiety was studied. Among all tested lipases, Novozyme SP 435 allowed to obtain optically active 4-(5-aryl-2H-tetrazol-2yl)butan-2-ol and 1-(5-aryl-2H-tetrazol-2yl)-propan-2-ol and their acetates with the highest optical purities (ee = 95%-99%) and excellent enantioselectivity (E>100). Some of the synthesized tetrazole derivatives were screened for their antifungal activity. Racemic mixtures of 4-[5-(4-chlorophenyl)-2H-tetrazol-2-yl)butan-2-ol as well as pure enantiomers of this compound showed promising antifungal activity against F. sambucinum, F. oxysporum, C. coccodes, and A. niger. © 2014 Wiley Periodicals, Inc.

Palladium-Catalyzed Direct C–H Arylation of Cyclic Enaminones with Aryl Iodides

PubMed Central

Yu, Yi-Yun; Bi, Lei

2013-01-01

A ligand-free method for the Pd-catalyzed direct arylation of cyclic enaminones using aryl iodides was developed. This method can be applied to a wide range of cyclic enaminones and aryl iodides with excellent C5-regioselectivity. Using widely available aryl iodides, the generality of this transformation provides easy access to a variety of 3-arylpiperidine structural motifs. PMID:23750615

Metal-free, visible-light-mediated direct C-H arylation of heteroarenes with aryl diazonium salts.

PubMed

Hari, Durga Prasad; Schroll, Peter; König, Burkhard

2012-02-15

Visible light along with 1 mol % eosin Y catalyzes the direct C-H bond arylation of heteroarenes with aryl diazonium salts by a photoredox process. We have investigated the scope of the reaction for several aryl diazonium salts and heteroarenes. The general and easy procedure provides a transition-metal-free alternative for the formation of aryl-heteroaryl bonds.

Biology-oriented drug synthesis (BIODS): In vitro β-glucuronidase inhibitory and in silico studies on 2-(2-methyl-5-nitro-1H-imidazol-1-yl)ethyl aryl carboxylate derivatives.

PubMed

Salar, Uzma; Khan, Khalid Mohammed; Taha, Muhammad; Ismail, Nor Hadiani; Ali, Basharat; Qurat-Ul-Ain; Perveen, Shahnaz; Ghufran, Mehreen; Wadood, Abdul

2017-01-05

Current study is based on the biology-oriented drug synthesis (BIODS) of 2-(2-methyl-5-nitro-1H-imidazol-1-yl)ethyl aryl carboxylate derivatives 1-26, by treating metronidazole with different aryl and hetero-aryl carboxylic acids in the presence of 1,1'-carbonyl diimidazole (CDI) as a coupling agent. Structures of all synthetic derivatives were confirmed with the help of various spectroscopic techniques such as EI-MS, 1 H -NMR and 13 C NMR. CHN elemental analyses were also found in agreement with the calculated values. Synthetic derivatives were evaluated to check their β-glucuronidase inhibitory activity which revealed that except few derivatives, all demonstrated good inhibition in the range of IC 50  = 1.20 ± 0.01-60.30 ± 1.40 μM as compared to the standard d-saccharic acid 1,4-lactone (IC 50  = 48.38 ± 1.05 μM). Compounds 1, 3, 4, 6, 9-19, and 21-24 were found to be potent analogs and showed superior activity than standard. Limited structure-activity relationship is suggested that the molecules having electron withdrawing groups like NO 2 , F, Cl, and Br, were displayed better activity than the compounds with electron donating groups such as Me, OMe and BuO. To verify these interpretations, in silico study was also performed, a good correlation was observed between bioactivities and docking studies. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Electrochemical Grafting of Graphene Nano Platelets with Aryl Diazonium Salts.

PubMed

Qiu, Zhipeng; Yu, Jun; Yan, Peng; Wang, Zhijie; Wan, Qijin; Yang, Nianjun

2016-10-26

To vary interfacial properties, electrochemical grafting of graphene nano platelets (GNP) with 3,5-dichlorophenyl diazonium tetrafluoroborate (aryl-Cl) and 4-nitrobenzene diazonium tetrafluoroborate (aryl-NO 2 ) was realized in a potentiodynamic mode. The covalently bonded aryl layers on GNP were characterized using atomic force microscopy and X-ray photoelectron spectroscopy. Electrochemical conversion of aryl-NO 2 into aryl-NH 2 was conducted. The voltammetric and impedance behavior of negatively and positively charged redox probes (Fe(CN) 6 3-/4- and Ru(NH 3 ) 6 2+/3+ ) on three kinds of aryl layers grafted on GNP reveal that their interfacial properties are determined by the charge states of redox probes and reactive terminal groups (-Cl, -NO 2 , -NH 2 ) in aryl layers. On aryl-Cl and aryl-NH 2 garted GNP, selective and sensitive monitoring of positively charged lead ions as well as negatively charged nitrite and sulfite ions was achieved, respectively. Such a grafting procedure is thus a perfect way to design and control interfacial properties of graphene.

Laccase-catalyzed α-arylation of benzoylacetonitrile with substituted hydroquinones

DOE PAGES

Cannatelli, Mark D.; Ragauskas, Arthur J.

2014-09-03

This article investigates a green method for α-arylation of a primary nitrile. Compounds possessing a benzylic nitrile have shown to exhibit biological activity. Laccases (benzenediol:oxygen oxidoreductase EC 1.10.3.2) were used as the catalysts to perform the cross-coupling reaction between benzoylacetonitrile and substituted hydroquinones. The corresponding 2-substituted 3-oxo-3-phenylpropanenitriles where synthesized in moderate to excellent yields in pH 7.0 buffered water under mild conditions. The substituent on the hydroquinone had a significant impact on product yields and regioselectivity of reaction. The use of laccases, which require O 2 as their only co-substrate and produce H 2O as their only by-product, to performmore » this transformation is an environmentally benign method for α-arylation of primary nitriles.« less

Palladium-Catalyzed Indole, Pyrrole, and Furan Arylation by Aryl Chlorides

PubMed Central

Nadres, Enrico T.; Lazareva, Anna; Daugulis, Olafs

2011-01-01

The palladium-catalyzed direct arylation of indoles, pyrroles, and furans by aryl chlorides has been demonstrated. The method employs a palladium acetate catalyst, 2-(dicyclohexylphosphino)-biphenyl ligand, and an inorganic base. Electron-rich and electron-poor aryl chlorides as well as chloropyridine coupling partners can be used and arylated heterocycles are obtained in moderate to good yields. Optimization of base, ligand, and solvent is required for achieving best results. PMID:21192652

In vitro anti-Giardia lamblia activity of 2-aryl-3-hydroxymethyl imidazo[1,2-a]pyridines and -pyrimidines, individually and in combination with albendazole.

PubMed

Velázquez-Olvera, Stephanía; Salgado-Zamora, Héctor; Jiménez-Cardoso, Enedina; Campos-Aldrete, Maria-Elena; Pérez-González, Cuauhtémoc; Ben Hadda, Taibi

2016-03-01

Giardiasis is a major diarrheal disease found throughout the world, the causative agent being the flagellate protozoan Giardia intestinalis. Infection is more common in children than in adults. The appearance of drug resistance has complicated the treatment of several parasitic diseases, including giardiasis. Thus, the aim of this investigation was to make an in vitro evaluation of the antigiardia response of synthetic derivatives 2-aryl-3-hydroxymethylimidazo[1,2-a]pyridines 1 and -pyrimidines 2 against trophozoites of Giardia lamblia WB, in comparison with the reference drug, albendazole. Additionally, the synergistic action of albendazole in combination with each of the most active 2-aryl-3-hydroxymethyl imidazo[1,2-a]pyridines and pyrimidines was also assessed. Based on the IC50 values obtained, the best anti-Giardia activity was provided by the 3-hydroxymethyl-4-fluorophenylimidazo[1,2-a]pyrimidine derivative 2c and the corresponding imidazo[1,2-a]pyrimidine with the p-tolyl substituent 2d, followed by 2a and 2b. These four compounds showed effectiveness at a concentration similar to that of albendazole. Regarding synergism, the IC50 of the combination of albendazole with 2a, 2b or 2c gave the best anti-Giardia action, showing greater efficacy than albendazole alone. Hence, G. lamblia WB showed high susceptibility to some 2-aryl-3-hydroxymethyl imidazo[1,2-a] pyrimidines, which acted synergistically when used in combination with albendazole. Copyright © 2015 Elsevier B.V. All rights reserved.

Conversion of aryl iodides into aryliodine(III) dichlorides by an oxidative halogenation strategy using 30% aqueous hydrogen peroxide in fluorinated alcohol.

PubMed

Podgorsek, Ajda; Iskra, Jernej

2010-04-20

Oxidative chlorination with HCl/H2O2 in 1,1,1-trifluoroethanol was used to transform aryl iodides into aryliodine(III) dihalides. In this instance 1,1,1-trifluoroethanol is not only the reaction medium, but is also an activator of hydrogen peroxide for the oxidation of hydrochloric acid to molecular chlorine. Aryliodine(III) dichlorides were formed in 72-91% isolated yields in the reaction of aryl iodides with 30% aqueous hydrogen peroxide and hydrochloric acid at ambient temperature. A study of the effect that substituents on the aromatic ring have on the formation and stability of aryliodine(III) dichlorides shows that the transformation is easier to achieve in the presence of the electron-donating groups (i.e. methoxy), but in this case the products rapidly decompose under the reported reaction conditions to form chlorinated arenes. The results suggest that oxidation of hydrogen chloride with hydrogen peroxide is the initial reaction step, while direct oxidation of aryl iodide with hydrogen peroxide is less likely to occur.

Synthesis and biological evaluation of some novel substituted 2,6-dimethyl-1,4-dihydropyridine-3,5-dicarboxamides

NASA Astrophysics Data System (ADS)

Jaismy Jacob, P.; Thomas, Anoop; Venkataraman, S.; Hareeshbabu, E.; Manju, S. L.

2017-11-01

A novel class of substituted 4-aryl-2,6-dimethyl-1,4-dihydropyridine-3,5-dicarboxamide has been synthesized by simple, modified Hantzsch condensation reaction using N-arylacetoacetamides, aryl aldehydes and ammonia. Characterisation of the newly synthesized compounds was carried out by spectral analysis (IR, 1H NMR and Mass Spectroscopy). Antimicrobial activity against Staphylococcus aureus, Escherichia coli and Candida albicans and antiulcer activity by aspirin induced and pyloric ligation ulcer model was studied. Results revealed that most of the compounds exhibit significant antimicrobial activity along with antiulcer activity. The compound 6i 4-dimethylamino phenyl group at 4th position of 1,4-dihydropyridine had shown 65% ulcer protection at 10 mg/kg administration in male albino rats.

Direct arylation/alkylation/magnesiation of benzyl alcohols in the presence of Grignard reagents via Ni-, Fe-, or Co-catalyzed sp3 C-O bond activation.

PubMed

Yu, Da-Gang; Wang, Xin; Zhu, Ru-Yi; Luo, Shuang; Zhang, Xiao-Bo; Wang, Bi-Qin; Wang, Lei; Shi, Zhang-Jie

2012-09-12

Direct application of benzyl alcohols (or their magnesium salts) as electrophiles in various reactions with Grignard reagents has been developed via transition metal-catalyzed sp(3) C-O bond activation. Ni complex was found to be an efficient catalyst for the first direct cross coupling of benzyl alcohols with aryl/alkyl Grignard reagents, while Fe, Co, or Ni catalysts could promote the unprecedented conversion of benzyl alcohols to benzyl Grignard reagents in the presence of (n)hexylMgCl. These methods offer straightforward pathways to transform benzyl alcohols into a variety of functionalities.

Preparation of catalytically active, covalent α-polylysine-enzyme conjugates via UV/vis-quantifiable bis-aryl hydrazone bond formation.

PubMed

Grotzky, Andrea; Manaka, Yuichi; Kojima, Taisuke; Walde, Peter

2011-01-10

Covalent UV/vis-quantifiable bis-aryl hydrazone bond formation was investigated for the preparation of conjugates between α-poly-d-lysine (PDL) and either α-chymotrypsin (α-CT) or horseradish peroxidase (HRP). PDL and the enzymes were first modified via free amino groups with the linking reagents succinimidyl 6-hydrazinonicotinate acetone hydrazone (S-HyNic, at pH 7.6) and succinimidyl 4-formylbenzoate (S-4FB, at pH 7.2), respectively. The modified PDL and enzymes were then conjugated at pH 4.7, whereby polymer chains carrying several enzymes were obtained. Kinetics of the bis-aryl hydrazone bond formation was investigated spectrophotometrically at 354 nm. Retention of the enzymatic activity after conjugate formation was confirmed by using the substrates N-succinimidyl-l-Ala-l-Ala-l-Pro-l-Phe-p-nitroanilide (for α-CT) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS, for HRP). Thus, not only a mild and efficient preparation and convenient quantification of a conjugate between the polycationic α-polylysine and enzymes could be shown, but also the complete preservation of the enzymatic activity.

Antitumor activity of JS-K [O2-(2,4-dinitrophenyl) 1-[(4-ethoxycarbonyl)piperazin-1-yl]diazen-1-ium-1,2-diolate] and related O2-aryl diazeniumdiolates in vitro and in vivo.

PubMed

Shami, Paul J; Saavedra, Joseph E; Bonifant, Challice L; Chu, Jingxi; Udupi, Vidya; Malaviya, Swati; Carr, Brian I; Kar, Siddhartha; Wang, Meifeng; Jia, Lee; Ji, Xinhua; Keefer, Larry K

2006-07-13

The literature provides evidence that metabolic nitric oxide (NO) release mediates the cytotoxic activities (against human leukemia and prostate cancer xenografts in mice) of JS-K, a compound of structure R(2)N-N(O)=NO-Ar for which R(2)N is 4-(ethoxycarbonyl)piperazin-1-yl and Ar is 2,4-dinitrophenyl. Here we present comparative data on the potencies of JS-K and 41 other O(2)-arylated diazeniumdiolates as inhibitors of HL-60 human leukemia cell proliferation, as well as in the NCI 51-cell-line screen for six of them. The data show JS-K to be the most potent of the 42 in both screens and suggest that other features of its structure and metabolism besides NO release may contribute importantly to its activity. Results with control compounds implicate JS-K's arylating ability, and the surprisingly low IC(50) value of the N-(ethoxycarbonyl)piperazine byproduct of NO release suggests a role for the R(2)N moiety. In addition to the above-mentioned in vivo activities, JS-K is shown here to be carcinostatic in a rat liver cancer model.

Platinum(0)-mediated C-O bond activation of ethers via an SN2 mechanism.

PubMed

Ortuño, Manuel A; Jasim, Nasarella A; Whitwood, Adrian C; Lledós, Agustí; Perutz, Robin N

2016-11-29

A computational study of the C(methyl)-O bond activation of fluorinated aryl methyl ethers by a platinum(0) complex Pt(PCyp 3 ) 2 (Cyp = cyclopentyl) (N. A. Jasim, R. N. Perutz, B. Procacci and A. C. Whitwood, Chem. Commun., 2014, 50, 3914) demonstrates that the reaction proceeds via an S N 2 mechanism. Nucleophilic attack of Pt(0) generates an ion pair consisting of a T-shaped platinum cation with an agostic interaction with a cyclopentyl group and a fluoroaryloxy anion. This ion-pair is converted to a 4-coordinate Pt(ii) product trans-[PtMe(OAr F )(PCyp 3 ) 2 ]. Structure-reactivity correlations are fully consistent with this mechanism. The Gibbs energy of activation is calculated to be substantially higher for aryl methyl ethers without fluorine substituents and higher still for alkyl methyl ethers. These conclusions are in accord with the experimental results. Further support was obtained in an experimental study of the reaction of Pt(PCy 3 ) 2 with 2,3,5,6-tetrafluoro-4-allyloxypyridine yielding the salt of the Pt(η 3 -allyl) cation and the tetrafluoropyridinolate anion [Pt(PCy 3 ) 2 (η 3 -allyl)][OC 5 NF 4 ]. The calculated activation energy for this reaction is significantly lower than that for fluorinated aryl methyl ethers.

Characterization of substituted aryl meroterpenoids from red seaweed Hypnea musciformis as potential antioxidants.

PubMed

Chakraborty, Kajal; Joseph, Deepu; Joy, Minju; Raola, Vamshi Krishna

2016-12-01

The ethyl acetate fraction of red seaweed Hypnea musciformis was purified to yield three substituted aryl meroterpenoids, namely, 2-(tetrahydro-5-(4-hydroxyphenyl)-4-pentylfuran-3-yl)-ethyl-4-hydroxybenzoate (1), 2-2-[(4-hydroxybenzoyl)-oxy]-ethyl-4-methoxy-4-2-[(4-methylpentyl)oxy]-3,4-dihydro-2H-6-pyranylbutanoic acid (2) and 3-((5-butyl-3-methyl-5,6-dihydro-2H-pyran-2-yl)-methyl)-4-methoxy-4-oxobutyl benzoate (3). The structures of these compounds, as well as their relative stereochemistries, were confirmed by exhaustive NMR spectroscopic data analyses. Compound 1 exhibited similar 2,2'-diphenylpicrylhydrazyl radical inhibiting and Fe(2+) ion chelating activities (IC50 25.05 and 350.7μM, respectively) as that of commercial antioxidant gallic acid (IC50 32.3 and 646.6μM, respectively), followed by 3 (IC50 231.2 and 667.9μM, respectively), and 2 (IC50 322.4 and 5115.3μM, respectively), in descending order of activities. Structure-activity relationship analysis revealed that the antioxidant activities of these compounds were directly proportional to the steric and hydrophobic parameters. The seaweed derived aryl meroterpenoids might serve as potential lead antioxidative molecules for use in pharmaceutical and food industries. Copyright © 2016 Elsevier Ltd. All rights reserved.

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

King, W.A.; Kubas, G.J.

The present invention provides: a composition of the formula M{sup +x}(Ga(Y){sub 4}{sup {minus}}){sub x} where M is a metal selected from the group consisting of lithium, sodium, potassium, cesium, calcium, strontium, thallium, and silver, x is an integer selected from the group consisting of 1 or 2, each Y is a ligand selected from the group consisting of aryl, alkyl, hydride and halide with the proviso that at least one Y is a ligand selected from the group consisting of aryl, alkyl and halide; a composition of the formula (R){sub x}Q{sup +}Ga(Y){sub 4}{sup {minus}} where Q is selected from themore » group consisting of carbon, nitrogen, sulfur, phosphorus and oxygen, each R is a ligand selected from the group consisting of alkyl, aryl, and hydrogen, x is an integer selected from the group consisting of 3 and 4 depending upon Q, and each Y is a ligand selected from the group consisting of aryl, alkyl, hydride and halide with the proviso that at least one Y is a ligand selected from the group consisting of aryl, alkyl and halide; an ionic polymerization catalyst composition including an active cationic portion and a gallium based weakly coordinating anion; and bridged anion species of the formula M{sup +x}{sub y}[X(GaY{sub 3}){sub z}]{sup {minus}y}{sub x} where M is a metal selected from the group consisting of lithium, sodium, potassium, magnesium, cesium, calcium, strontium, thallium, and silver, x is an integer selected from the group consisting of 1 or 2, X is a bridging group between two gallium atoms, y is an integer selected from the group consisting 1 and 2, z is an integer of at least 2, each Y is a ligand selected from the group consisting of aryl, alkyl, hydride and halide with the proviso that at least one Y is a ligand selected from the group consisting of aryl, alkyl and halide.« less

Gallium based low-interaction anions

DOEpatents

King, Wayne A.; Kubas, Gregory J.

2000-01-01

The present invention provides: a composition of the formula M.sup.+x (Ga(Y).sub.4.sup.-).sub.x where M is a metal selected from the group consisting of lithium, sodium, potassium, cesium, calcium, strontium, thallium, and silver, x is an integer selected from the group consisting of 1 or 2, each Y is a ligand selected from the group consisting of aryl, alkyl, hydride and halide with the proviso that at least one Y is a ligand selected from the group consisting of aryl, alkyl and halide; a composition of the formula (R).sub.x Q.sup.+ Ga(Y).sub.4.sup.- where Q is selected from the group consisting of carbon, nitrogen, sulfur, phosphorus and oxygen, each R is a ligand selected from the group consisting of alkyl, aryl, and hydrogen, x is an integer selected from the group consisting of 3 and 4 depending upon Q, and each Y is a ligand selected from the group consisting of aryl, alkyl, hydride and halide with the proviso that at least one Y is a ligand selected from the group consisting of aryl, alkyl and halide; an ionic polymerization catalyst composition including an active cationic portion and a gallium based weakly coordinating anion; and bridged anion species of the formula M.sup.+x.sub.y [X(Ga(Y.sub.3).sub.z ].sup.-y.sub.x where M is a metal selected from the group consisting of lithium, sodium, potassium, magnesium, cesium, calcium, strontium, thallium, and silver, x is an integer selected from the group consisting of 1 or 2, X is a bridging group between two gallium atoms, y is an integer selected from the group consisting 1 and 2, z is an integer of at least 2, each Y is a ligand selected from the group consisting of aryl, alkyl, hydride and halide with the proviso that at least one Y is a ligand selected from the group consisting of aryl, alkyl and halide.

Regioselective reaction: synthesis, characterization and pharmacological activity of some new Mannich and Schiff bases containing sydnone.

PubMed

Nithinchandra; Kalluraya, B; Aamir, S; Shabaraya, A R

2012-08-01

A novel series of 1-substituted aminomethyl-3-[1-(4-isobutylphenyl)ethyl]-4-(3-aryl-4-sydnonylidene) amino-1,2,4-triazol-5-thiones (9), was prepared from the 3-[1-(4-isobutylphenyl)ethyl]-4-(3-aryl-4-sydnonylidene) amino 5-mercapto-1,2,4-triazoles (8) by aminomethylation with formaldehyde and secondary amine. The structures of Schiff bases (8) and Mannich bases (9) were characterized on the basis of IR, NMR, mass spectra1 data and elemental analysis. The newly synthesized compounds were screened for their anti-inflammatory and analgesic activities. Mannich bases (9) carrying piperidine and morpholine residues showed promising anti-inflammatory and analgesic activity. Copyright © 2012 Elsevier Masson SAS. All rights reserved.

Chemical basis for the phytotoxicity of N-aryl hydroxamic acids and acetanilide analogues.

PubMed

Bravo, Héctor R; Villarroel, Elisa; Copaja, Sylvia V; Argandoña, Victor H

2008-01-01

Germination inhibition activity of N-aryl hydroxamic acids and acetanilide analogues was measured on lettuce seeds (Lactuca sativa). Lipophilicity of the compounds was determined by HPLC. A correlation between lipophilicity values and percentage of germination inhibition was established. A model mechanism of action for auxin was used for analyzing the effect of the substituent at the alpha carbon atom (Ca) on the polarization of hydroxamic and amide functions in relation to the germination inhibition activity observed. Results suggest that the lipophilic and acidic properties play an important role in the phytotoxicity of the compounds. A test with the microalga Chlorella vulgaris was used to evaluate the potential herbicide activity of the hydroxamic acids and acetanilides.

Manipulation of a DNA aptamer-protein binding site through arylation of internal guanine residues.

PubMed

Van Riesen, Abigail J; Fadock, Kaila L; Deore, Prashant S; Desoky, Ahmed; Manderville, Richard A; Sowlati-Hashjin, Shahin; Wetmore, Stacey D

2018-05-23

Chemically modified aptamers have the opportunity to increase aptamer target binding affinity and provide structure-activity relationships to enhance our understanding of molecular target recognition by the aptamer fold. In the current study, 8-aryl-2'-deoxyguanosine nucleobases have been inserted into the G-tetrad and central TGT loop of the thrombin binding aptamer (TBA) to determine their impact on antiparallel G-quadruplex (GQ) folding and thrombin binding affinity. The aryl groups attached to the dG nucleobase vary greatly in aryl ring size and impact on GQ stability (∼20 °C change in GQ thermal melting (Tm) values) and thrombin binding affinity (17-fold variation in dissociation constant (Kd)). At G8 of the central TGT loop that is distal from the aptamer recognition site, the probes producing the most stable GQ structure exhibited the strongest thrombin binding affinity. However, within the G-tetrad, changes to the electron density of the dG component within the modified nucleobase can diminish thrombin binding affinity. Detailed molecular dynamics (MD) simulations on the modified TBA (mTBA) and mTBA-protein complexes demonstrate how the internal 8-aryl-dG modification can manipulate the interactions between the DNA nucleobases and the amino acid residues of thrombin. These results highlight the potential of internal fluorescent nuclobase analogs (FBAs) to broaden design options for aptasensor development.

Palladium-Catalyzed α-Arylation of Aryl Nitromethanes

PubMed Central

2015-01-01

Catalytic conditions for the α-arylation of aryl nitromethanes have been discovered using parallel microscale experimentation, despite two prior reports of the lack of reactivity of these aryl nitromethane precursors. The method efficiently provides a variety of substituted, isolable diaryl nitromethanes. In addition, it is possible to sequentially append two different aryl groups to nitromethane. Mild oxidation conditions were identified to afford the corresponding benzophenones via the Nef reaction, and reduction conditions were optimized to afford several diaryl methylamines. PMID:26584680

5-(1-Aryl-3-(thiophen-2-yl)-1H-pyrazol-4-yl)-1H-tetrazoles: Synthesis, structural characterization, Hirshfeld analysis, anti-inflammatory and anti-bacterial studies

NASA Astrophysics Data System (ADS)

Kumbar, Mahadev N.; Kamble, Ravindra R.; Dasappa, Jagadeesh Prasad; Bayannavar, Praveen K.; Khamees, Hussien Ahmed; Mahendra, M.; Joshi, Shrinivas D.; Dodamani, Suneel; Rasal, V. P.; Jalalpure, Sunil

2018-05-01

A series of novel 5-(1-aryl-3-(thiophen-2-yl)-1H-pyrazol-4-yl)-1H-tetrazoles 7(h-s) were designed and synthesized. Structural characterization was done by spectral and single crystal X-ray studies. The intermolecular interactions of compound 7n were quantified and visualized using Hirshfeld surface analysis. Structures of newly synthesized compounds were docked into active site of COX-2 enzyme PDB:

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

Ding, Shunmin; Tian, Chengcheng; Zhu, Xiang

Transition-metal-catalyzed cyanation of aryl halides is a common route to benzonitriles, which are integral to many industrial procedures. However, traditional homogeneous catalysts for such processes are expensive and suffer poor recyclability, so a heterogeneous analogue is highly desired. A novel spatial modulation approach has been developed in this paper to fabricate a heterogeneous Pd-metalated nanoporous polymer, which catalyzes the cyanation of aryl halides without need for ligands. Finally, the catalyst displays high activity in the synthesis of benzonitriles, including high product yields, excellent stability and recycling, and broad functional-group tolerance.

Enantiomerically pure 3-aryl- and 3-hetaryl-2-hydroxypropanoic acids by chemoenzymatic reduction of 2-oxo acids.

PubMed

Sivanathan, Sivatharushan; Körber, Florian; Tent, Jannis Aron; Werner, Svenja; Scherkenbeck, Jürgen

2015-03-06

Phenyllactic acids are found in numerous natural products as well as in active substances used in medicine or plant protection. Enantiomerically pure phenyllactic acids are available by transition-metal-catalyzed hydrogenations or chemoenzymatic reductions of the corresponding 3-aryl-2-oxopropanoic acids. We show here that d-lactate dehydrogenase from Staphylococcus epidermidis reduces a broad spectrum of 2-oxo acids, which are difficult substrates for transition-metal-catalyzed reactions, with excellent enantioselectivities in a simple experimental setup.

Design, Sustainable Synthesis, and Programmed Reactions of Templated N-Heteroaryl-Fused Vinyl Sultams.

PubMed

Laha, Joydev K; Sharma, Shubhra; Kirar, Seema; Banerjee, Uttam C

2017-09-15

A de novo design and synthesis of N-heteroaryl-fused vinyl sultams as templates for programming chemical reactions on vinyl sultam periphery or (hetero)aryl ring is described. The key features include rational designing and sustainable synthesis of the template, customized reactions of vinyl sultams at C═C bond or involving N-S bond cleavage, and reactions on the periphery of the heteroaryl ring for late-stage diversification. The simple, easy access to the template coupled with opportunities for the synthesis of diversely functionalized heterocyles from a single template constitutes a rare study in contemporary organic synthesis.

Role of aryl hydrocarbon receptor in mesenchymal stromal cell activation: A minireview.

PubMed

de Almeida, Danilo Candido; Evangelista, Laura Sibele Martins; Câmara, Niels Olsen Saraiva

2017-09-26

Mesenchymal stromal cells (MSCs) possess great therapeutic advantages due to their ability to produce a diverse array of trophic/growth factors related to cytoprotection and immunoregulation. MSC activation via specific receptors is a crucial event for these cells to exert their immunosuppressive response. The aryl-hydrocarbon receptor (AhR) is a sensitive molecule for external signals and it is expressed in MSCs and, upon positive activation, may potentially regulate the MSC-associated immunomodulatory function. Consequently, signalling pathways linked to AhR activation can elucidate some of the molecular cascades involved in MSC-mediated immunosuppression. In this minireview, we have noted some important findings concerning MSC regulation via AhR, highlighting that its activation is associated with improvement in migration and immunoregulation, as well as an increase in pro-regenerative potential. Thus, AhR-mediated MSC activation can contribute to new perspectives on MSC-based therapies, particularly those directed at immune-associated disorders.

Synthesis and anti-inflammatory activity of some benzofuran and benzopyran-4-one derivatives.

PubMed

Ragab, Fatma Abd El-Fattah; Eid, Nahed Mahmoud; Hassan, Ghaneya Sayed; Nissan, Yassin Mohammed

2012-01-01

New series of furosalicylic acids 3a-c, furosalicylanilides 6a-n, furobenzoxazines 8a-f, 1-benzofuran-3-arylprop-2-en-1-ones 12a,b, 6-(aryl-3-oxoprop-1-enyl)-4H-chromen-4-ones 16a-c and 6-[6-aryl-2-thioxo-2,5-dihydropyrimidin-4-yl]-4H-chromen-4-ones 17a-c were synthesized. Anti-inflammatory activity evaluation was performed using carrageenan-induced paw edema model in rats and prostaglandin E(2) (PGE(2)) synthesis inhibition activity. Some of the tested compounds revealed comparable activity with less ulcerogenic effect than Diclofenac at a dose 100 mg/kg. All the synthesized compounds were docked on the active site of cyclooxygenase-2 (COX-2) enzyme and most of them showed good interactions with the amino acids of the active site comparable to the interactions exhibited by Diclofenac.

Initial Reactivity of Linkages and Monomer Rings in Lignin Pyrolysis Revealed by ReaxFF Molecular Dynamics.

PubMed

Zhang, Tingting; Li, Xiaoxia; Guo, Li

2017-10-24

The initial conversion pathways of linkages and their linked monomer units in lignin pyrolysis were investigated comprehensively by ReaxFF MD simulations facilitated by the unique VARxMD for reaction analysis. The simulated molecular model contains 15 920 atoms and was constructed on the basis of Adler's softwood lignin model. The simulations uncover the initial conversion ratio of various linkages and their linked aryl monomers. For linkages and their linked monomer aryl rings of α-O-4, β-O-4 and α-O-4 & β-5, the C α /C β ether bond cracking dominates the initial pathway accounting for at least up to 80% of their consumption. For the linkage of β-β & γ-O-α, both the C α -O ether bond cracking and its linked monomer aryl ring opening are equally important. Ring-opening reactions dominate the initial consumption of other 4-O-5, 5-5, β-1, β-2, and β-5 linkages and their linked monomers. The ether bond cracking of C α -O and C β -O occurs at low temperature, and the aryl ring-opening reactions take place at relatively high temperature. The important intermediates leading to the stable aryl ring opening are the phenoxy radicals, the bridged five-membered and three-membered rings and the bridged six-membered and three-membered rings. In addition, the reactivity of a linkage and its monomer aryl ring may be affected by other linkages. The ether bond cracking of α-O-4 and β-O-4 linkages can activate its neighboring linkage or monomer ring through the formed phenoxy radicals as intermediates. The important intermediates revealed in this article should be of help in deepening the understanding of the controlling mechanism for producing aromatic chemicals from lignin pyrolysis.

Rhodium Catalyzed Intramolecular C-H Insertion of α-Aryl-α-diazo Ketones

PubMed Central

Taber, Douglass F.; Tian, Weiwei

2011-01-01

Direct diazo transfer proceeds smoothly with α-aryl ketones. The derived α-aryl-α-diazo ketones cyclize efficiently with Rh catalysis to give the corresponding α-aryl cyclopentanones. PMID:17385917

Synthesis of Benzannulated Medium-ring Lactams via a Tandem Oxidative Dearomatization-Ring Expansion Reaction.

PubMed

Guney, Tezcan; Wenderski, Todd A; Boudreau, Matthew W; Tan, Derek S

2018-06-23

Medium-ring natural products exhibit diverse biological activities but such scaffolds are underrepresented in probe and drug discovery efforts due to the limitations of classical macrocyclization reactions. We report herein a tandem oxidative dearomatization-ring-expanding rearoma¬tization (ODRE) reaction that generates benzannulated medium-ring lactams directly from simple bicyclic substrates. The reaction accommodates diverse aryl substrates (haloarenes, aryl ethers, aryl amides, heterocycles) and strategic incorporation of a bridgehead alcohol generates a versatile ketone moiety in the products amenable to downstream modifications. Cheminformatic analysis indicates that these medium rings access regions of chemical space that overlap with related natural products and are distinct from synthetic drugs, setting the stage for their use in discovery screening against novel biological targets. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Direct asymmetric aldol reaction of aryl ketones with aryl aldehydes catalyzed by chiral BINOL-derived zincate catalyst.

PubMed

Li, Hong; Da, Chao-Shan; Xiao, Yu-Hua; Li, Xiao; Su, Ya-Ning

2008-09-19

Direct asymmetric aldol reaction of aryl ketones with aryl aldehydes catalyzed by chiral metal complex is reported for the first time herein. Two novel semicrown chiral ligands 1a and 1b were synthesized from (S)- and (R)-BINOL, respectively, and then employed to catalyze the direct asymmetric aldol addition of aryl ketones to aryl aldehydes. Introduced with 2.0 equiv of diethylzinc, 1b had higher enantioselectivity than 1a. Up to 97% yield and up to 80% enantioselectivity were achieved.

Sontochin as a Guide to the Development of Drugs against Chloroquine-Resistant Malaria

PubMed Central

Pou, Sovitj; Winter, Rolf W.; Nilsen, Aaron; Kelly, Jane Xu; Li, Yuexin; Doggett, J. Stone; Riscoe, Erin W.; Wegmann, Keith W.; Hinrichs, David J.

2012-01-01

Sontochin was the original chloroquine replacement drug, arising from research by Hans Andersag 2 years after chloroquine (known as “resochin” at the time) had been shelved due to the mistaken perception that it was too toxic for human use. We were surprised to find that sontochin, i.e., 3-methyl-chloroquine, retains significant activity against chloroquine-resistant strains of Plasmodium falciparum in vitro. We prepared derivatives of sontochin, “pharmachins,” with alkyl or aryl substituents at the 3 position and with alterations to the 4-position side chain to enhance activity against drug-resistant strains. Modified with an aryl substituent in the 3 position of the 7-chloro-quinoline ring, Pharmachin 203 (PH-203) exhibits low-nanomolar 50% inhibitory concentrations (IC50s) against drug-sensitive and multidrug-resistant strains and in vivo efficacy against patent infections of Plasmodium yoelii in mice that is superior to chloroquine. Our findings suggest that novel 3-position aryl pharmachin derivatives have the potential for use in treating drug resistant malaria. PMID:22508305

Electrochemical supercapacitors

DOEpatents

Rudge, Andrew J.; Ferraris, John P.; Gottesfeld, Shimshon

1996-01-01

A new class of electrochemical capacitors provides in its charged state a positive electrode including an active material of a p-doped material and a negative electrode including an active material of an n-doped conducting polymer, where the p-doped and n-doped materials are separated by an electrolyte. In a preferred embodiment, the positive and negative electrode active materials are selected from conducting polymers consisting of polythiophene, polymers having an aryl group attached in the 3-position, polymers having aryl and alkyl groups independently attached in the 3- and 4-positions, and polymers synthesized from bridged dimers having polythiophene as the backbone. A preferred electrolyte is a tetraalykyl ammonium salt, such as tetramethylammonium trifluoromethane sulphonate (TMATFMS), that provides small ions that are mobile through the active material, is soluble in acetonitrile, and can be used in a variety of capacitor configurations.

Inhibition of the pore-forming protein perforin by a series of aryl-substituted isobenzofuran-1(3H)-ones.

PubMed

Spicer, Julie A; Huttunen, Kristiina M; Miller, Christian K; Denny, William A; Ciccone, Annette; Browne, Kylie A; Trapani, Joseph A

2012-02-01

An aryl-substituted isobenzofuran-1(3H)-one lead compound was identified from a high throughput screen designed to find inhibitors of the lymphocyte pore-forming protein perforin. A series of analogs were then designed and prepared, exploring structure-activity relationships through variation of 2-thioxoimidazolidin-4-one and furan subunits on an isobenzofuranone core. The ability of the resulting compounds to inhibit the lytic activity of both isolated perforin protein and perforin delivered in situ by intact KHYG-1 natural killer effector cells was determined. Several compounds showed excellent activity at concentrations that were non-toxic to the killer cells. This series represents a significant improvement on previous classes of compounds, being substantially more potent and largely retaining activity in the presence of serum. Copyright © 2011 Elsevier Ltd. All rights reserved.

Structural basis of stereospecificity in the bacterial enzymatic cleavage of β-aryl ether bonds in lignin

DOE PAGES

Helmich, Kate E.; Pereira, Jose Henrique; Gall, Daniel L.; ...

2015-12-04

Here, lignin is a combinatorial polymer comprising monoaromatic units that are linked via covalent bonds. Although lignin is a potential source of valuable aromatic chemicals, its recalcitrance to chemical or biological digestion presents major obstacles to both the production of second-generation biofuels and the generation of valuable coproducts from lignin's monoaromatic units. Degradation of lignin has been relatively well characterized in fungi, but it is less well understood in bacteria. A catabolic pathway for the enzymatic breakdown of aromatic oligomers linked via β-aryl ether bonds typically found in lignin has been reported in the bacterium Sphingobium sp. SYK-6. Here, wemore » present x-ray crystal structures and biochemical characterization of the glutathione-dependent β-etherases, LigE and LigF, from this pathway. The crystal structures show that both enzymes belong to the canonical two-domain fold and glutathione binding site architecture of the glutathione S-transferase family. Mutagenesis of the conserved active site serine in both LigE and LigF shows that, whereas the enzymatic activity is reduced, this amino acid side chain is not absolutely essential for catalysis. The results include descriptions of cofactor binding sites, substrate binding sites, and catalytic mechanisms. Because β-aryl ether bonds account for 50–70% of all interunit linkages in lignin, understanding the mechanism of enzymatic β-aryl ether cleavage has significant potential for informing ongoing studies on the valorization of lignin.« less

Effects of exposure to air pollution and smoking on the placental aryl hydrocarbon hydroxylase (AHH) activity

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

Hincal, F.

Aryl hydrocarbon hydroxylase (AHH) activities were determined in placental tissues of 152 nonsmoker or exsmoker women who live in Ankara and 125 nonsmoker women who live in areas surrounding Ankara. Levels of AHH were also determined in the placentas of 52 cigarette smokers. The mean AHH activity in the Ankara group was 11.17 +/- 5.41; in the control group, 6.44 +/- 5.48; and for smokers, 45.68 +/- 53.36, which indicates significant differences (p < .001). There was a strong correlation (r = 0.89) between the AHH activities of individuals who live in Ankara and smoke content of the air. Placentalmore » AHH activity did not show any relation to the age, nutritional and dietary habits, factors of indoor pollution, duration of pregnancy, nor did the weight, length and Apgar score of the babies.« less

Maleimide-activated aryl diazonium salts for electrode surface functionalization with biological and redox-active molecules.

PubMed

Harper, Jason C; Polsky, Ronen; Wheeler, David R; Brozik, Susan M

2008-03-04

A versatile and simple method is introduced for formation of maleimide-functionalized surfaces using maleimide-activated aryl diazonium salts. We show for the first time electrodeposition of N-(4-diazophenyl)maleimide tetrafluoroborate on gold and carbon electrodes which was characterized via voltammetry, grazing angle FTIR, and ellipsometry. Electrodeposition conditions were used to control film thickness and yielded submonolayer-to-multilayer grafting. The resulting phenylmaleimide surfaces served as effective coupling agents for electrode functionalization with ferrocene and the redox-active protein cytochrome c. The utility of phenylmaleimide diazonium toward formation of a diazonium-activated conjugate, followed by direct electrodeposition of the diazonium-modified DNA onto the electrode surface, was also demonstrated. Effective electron transfer was obtained between immobilized molecules and the electrodes. This novel application of N-phenylmaleimide diazonium may facilitate the development of bioelectronic devices including biofuel cells, biosensors, and DNA and protein microarrays.

The level of aryl acylamidase activity displayed by human butyrylcholinesterase depends on its molecular distribution.

PubMed

Montenegro, M F; Moral-Naranjo, M T; Páez de la Cadena, M; Campoy, F J; Muñoz-Delgado, E; Vidal, C J

2008-09-25

Butyrylcholinesterase (BuChE) and acetylcholinesterase (AChE) display both esterase and aryl acylamidase (AAA) activities. Their AAA activity can be measured using o-nitroacetanilide (ONA). In human samples depleted of acetylcholinesterase, we noticed that the ratio of amidase to esterase activities varied depending on the source, despite both activities being due to BuChE. Searching for an explanation, we compared the activities of BuChE molecular forms in samples of human colon, kidney and serum, and observed that BuChE monomers (G(1)) hydrolyzed o-nitroacetanilide much faster than tetramers (G(4)). This fact suggested that association might cause differences in the AAA site between single and polymerized subunits. This and other post-translational modifications in BuChE subunits probably determine their level of AAA activity. The higher amidase activity of monomers could justify the presence of single BuChE subunits in cells as a way to preserve the AAA activity of BuChE, which could be lost by oligomerization.

Solvent-free synthesis, spectral correlations and antimicrobial activities of some aryl E 2-propen-1-ones

NASA Astrophysics Data System (ADS)

Sathiyamoorthi, K.; Mala, V.; Sakthinathan, S. P.; Kamalakkannan, D.; Suresh, R.; Vanangamudi, G.; Thirunarayanan, G.

2013-08-01

Totally 38 aryl E 2-propen-1-ones including nine substituted styryl 4-iodophenyl ketones have been synthesised using solvent-free SiO2-H3PO4 catalyzed Aldol condensation between respective methyl ketones and substituted benzaldehydes under microwave irradiation. The yields of the ketones are more than 80%. The synthesised chalcones were characterized by their analytical, physical and spectroscopic data. The spectral frequencies of synthesised substituted styryl 4-iodophenyl ketones have been correlated with Hammett substituent constants, F and R parameters using single and multi-linear regression analysis. The antimicrobial activities of 4-iodophenyl chalcones have been studied using Bauer-Kirby method.

Investigations on the synthesis and pharmacological properties of 4-alkoxy-2-[2-hydroxy-3-(4-aryl-1-piperazinyl)propyl]-6-methyl-1H-pyrrolo[3,4-c]pyridine-1,3(2H)-diones.

PubMed

Sladowska, Helena; Filipek, Barbara; Szkatuła, Dominika; Sabiniarz, Aleksandra; Kardasz, Małgorzata; Potoczek, Joanna; Sieklucka-Dziuba, Maria; Rajtar, Grazyna; Kleinrok, Zdzisław; Lis, Tadeusz

2002-11-01

Synthesis of 2-[2-hydroxy-3-(4-aryl-1-piperazinyl)propyl] derivatives of 4-alkoxy-6-methyl-1H-pyrrolo[3,4-c]pyridine-1,3(2H)-diones (8-12) is described. The chlorides used in the above synthesis can exist in two isomeric forms: chain (18-20) and cyclic (19a, 20a). The compounds 8-12 exhibited potent analgesic activity which was superior than that of acetylsalicylic acid in two different tests. Most of the investigated imides suppressed significantly spontaneous locomotor activity in mice.

One-pot syntheses of blue-luminescent 4-aryl-1H-benzo[f]isoindole-1,3(2H)-diones by T3P® activation of 3-arylpropiolic acids.

PubMed

Denißen, Melanie; Kraus, Alexander; Reiss, Guido J; Müller, Thomas J J

2017-01-01

In situ activation of 3-arylpropiolic acids with T3P ® ( n -propylphosphonic acid anhydride) initiates a domino reaction furnishing 4-arylnaphtho[2,3- c ]furan-1,3-diones in excellent yields. Upon employing these anhydrides as reactive intermediates blue-luminescent 4-aryl-1 H -benzo[ f ]isoindole-1,3(2 H )-diones are formed by consecutive pseudo three-component syntheses in a one-pot fashion. The Stokes shifts correlate excellently with the Hammett-Taft σ R parameter indicating an extended degree of resonance stabilization in the vibrationally relaxed excited singlet state.

One-pot syntheses of blue-luminescent 4-aryl-1H-benzo[f]isoindole-1,3(2H)-diones by T3P® activation of 3-arylpropiolic acids

PubMed Central

Denißen, Melanie; Kraus, Alexander; Reiss, Guido J

2017-01-01

In situ activation of 3-arylpropiolic acids with T3P® (n-propylphosphonic acid anhydride) initiates a domino reaction furnishing 4-arylnaphtho[2,3-c]furan-1,3-diones in excellent yields. Upon employing these anhydrides as reactive intermediates blue-luminescent 4-aryl-1H-benzo[f]isoindole-1,3(2H)-diones are formed by consecutive pseudo three-component syntheses in a one-pot fashion. The Stokes shifts correlate excellently with the Hammett–Taft σR parameter indicating an extended degree of resonance stabilization in the vibrationally relaxed excited singlet state. PMID:29181114

Merging C-H activation and alkene difunctionalization at room temperature: a palladium-catalyzed divergent synthesis of indoles and indolines.

PubMed

Manna, Manash Kumar; Hossian, Asik; Jana, Ranjan

2015-02-06

A palladium-catalyzed 1,2-carboamination through C-H activation at room temperature is reported for the synthesis of 2-arylindoles, and indolines from readily available, inexpensive aryl ureas and vinyl arenes. The reaction initiates with a urea-directed electrophilic ortho palladation, alkene insertion, and β-hydride elimination sequences to provide the Fujiwara-Moritani arylation product. Subsequently, aza-Wacker cyclization, and β-hydride elimination provide the 2-arylindoles in high yields. Intercepting the common σ-alkyl-Pd intermediate, corresponding indolines are also achieved. The indoline formation is attributed to the generation of stabilized, cationic π-benzyl-Pd species to suppress β-hydride elimination.

The Ketene-Surrogate Coupling: Catalytic Conversion of Aryl Iodides to Aryl Ketenes via Ynol Ethers**

PubMed Central

Zhang, Wenhan; Ready, Joseph M.

2014-01-01

tert-Butoxyacetylene is shown to undergo Sonogashira coupling with aryl iodides to yield aryl-substituted tert-butyl ynol ethers. These intermediates participate in a [1,5]-hydride shift, which results in the extrusion of isobutylene and the generation of aryl ketenes. The ketenes are trapped in situ with multiple nucleophiles or undergoelectrocyclic ring closure to yield hydroxynaphthalenes and quinolines. PMID:24975840

Transition-metal-catalyzed direct arylation of (hetero)arenes by C-H bond cleavage.

PubMed

Ackermann, Lutz; Vicente, Rubén; Kapdi, Anant R

2009-01-01

The area of transition-metal-catalyzed direct arylation through cleavage of C-H bonds has undergone rapid development in recent years, and is becoming an increasingly viable alternative to traditional cross-coupling reactions with organometallic reagents. In particular, palladium and ruthenium catalysts have been described that enable the direct arylation of (hetero)arenes with challenging coupling partners--including electrophilic aryl chlorides and tosylates as well as simple arenes in cross-dehydrogenative arylations. Furthermore, less expensive copper, iron, and nickel complexes were recently shown to be effective for economically attractive direct arylations.

Oculomotor Deficits in Aryl Hydrocarbon Receptor Null Mouse

PubMed Central

Chevallier, Aline; Mialot, Antoine; Petit, Jean-Maurice; Fernandez-Salguero, Pedro; Barouki, Robert

2013-01-01

The Aryl hydrocarbon Receptor or AhR, a ligand-activated transcription factor, is known to mediate the toxic and carcinogenic effects of various environmental pollutants such as 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD). Recent studies in Caenorhabditis elegans and Drosophila melanogaster show that the orthologs of the AhR are expressed exclusively in certain types of neurons and are implicated in the development and the homeostasis of the central nervous system. While physiological roles of the AhR were demonstrated in the mammalian heart, liver and gametogenesis, its ontogenic expression and putative neural functions remain elusive. Here, we report that the constitutive absence of the AhR in adult mice (AhR−/−) leads to abnormal eye movements in the form of a spontaneous pendular horizontal nystagmus. To determine if the nystagmus is of vestibular, visual, or cerebellar origin, gaze stabilizing reflexes, namely vestibulo-ocular and optokinetic reflexes (VOR and OKR), were investigated. The OKR is less effective in the AhR−/− mice suggesting a deficit in the visuo-motor circuitry, while the VOR is mildly affected. Furthermore, the AhR is expressedin the retinal ganglion cells during the development, however electroretinograms revealed no impairment of retinal cell function. The structure of the cerebellum of the AhR−/− mice is normal which is compatible with the preserved VOR adaptation, a plastic process dependent on cerebellar integrity. Finally, intoxication with TCDD of control adults did not lead to any abnormality of the oculomotor control. These results demonstrate that the absence of the AhR leads to acquired central nervous system deficits in the adults. Given the many common features between both AhR mouse and human infantile nystagmus syndromes, the AhR−/− mice might give insights into the developmental mechanisms which lead to congenital eye disorders. PMID:23301081

Efficient one-step Suzuki arylation of unprotected halonucleosides, using water-soluble palladium catalysts.

PubMed

Western, Elizabeth C; Daft, Jonathan R; Johnson, Edward M; Gannett, Peter M; Shaughnessy, Kevin H

2003-08-22

Modification of nucleosides to give pharmaceutically active compounds, mutagenesis models, and oligonucleotide structural probes continues to be of great interest. The aqueous-phase modification of unprotected halonucleosides is reported herein. Using a catalyst derived from tris(3-sulfonatophenyl)phosphine (TPPTS) and palladium acetate, 8-bromo-2'-deoxyguanosine (8-BrdG) is coupled with arylboronic acids to give 8-aryl-2'-deoxyguanosine adducts (8-ArdG) in excellent yield in a 2:1 water:acetonitrile solvent mixture. The TPPTS ligand was found to be superior to water-soluble alkylphosphines for this coupling reaction. The coupling chemistry has been extended to 8-bromo-2'-deoxyadenosine (8-BrdA) and 5-iodo-2'-deoxyuridine (5-IdU), as well as the ribonucleosides 8-bromoguanosine and 8-bromoadenosine. Good to excellent yields of arylated adducts are obtained in all cases. With use of tri(4,6-dimethyl-3-sulfonatophenyl)phosphine (TXPTS), the Suzuki coupling of 8-BrdA and 5-IdU can be accomplished in less than 1 h at room temperature. This methodology represents an efficient and general method for halonucleoside arylation that does not require prior protection of the nucleoside.

Aryl imidazylates and aryl sulfates as electrophiles in metal-free ArS(N)1 reactions.

PubMed

Qrareya, Hisham; Protti, Stefano; Fagnoni, Maurizio

2014-12-05

Some oxygen-bonded substituents were investigated as leaving groups in photoinduced ArS(N)1 reactions. Irradiation of aryl imidazylates and of the corresponding imidazolium salts mainly caused homolysis of the ArO-S bond. However, previously unexplored trifluoroethoxy aryl sulfates were found to undergo efficient metal-free arylation. The sulfates were conveniently generated in situ by dissolving the corresponding imidazolium salts in basic 2,2,2-trifluoroethanol.

Vinyldisiloxanes: their synthesis, cross coupling and applications.

PubMed

Sore, Hannah F; Boehner, Christine M; Laraia, Luca; Logoteta, Patrizia; Prestinari, Cora; Scott, Matthew; Williams, Katharine; Galloway, Warren R J D; Spring, David R

2011-01-21

During the studies towards the development of pentafluorophenyldimethylsilanes as a novel organosilicon cross coupling reagent it was revealed that the active silanolate and the corresponding disiloxane formed rapidly under basic conditions. The discovery that disiloxanes are in equilibrium with the silanolate led to the use of disiloxanes as cross coupling partners under fluoride free conditions. Our previous report focused on the synthesis and base induced cross coupling of aryl substituted vinyldisiloxanes with aryl halides; good yields and selectivities were achieved. As a continuation of our research, studies into the factors which influence the successful outcome of the cross coupling reaction with both alkyl and aryl substituted vinyldisiloxanes were examined and a proposed mechanism discussed. Further investigation into expanding the breadth and diversity of substituted vinyldisiloxanes in cross coupling was explored and applied to the synthesis of unsymmetrical trans-stilbenes and cyclic structures containing the trans-alkene architecture.

Asymmetric Catalysis with Organic Azides and Diazo Compounds Initiated by Photoinduced Electron Transfer.

PubMed

Huang, Xiaoqiang; Webster, Richard D; Harms, Klaus; Meggers, Eric

2016-09-28

Electron-acceptor-substituted aryl azides and α-diazo carboxylic esters are used as substrates for visible-light-activated asymmetric α-amination and α-alkylation, respectively, of 2-acyl imidazoles catalyzed by a chiral-at-metal rhodium-based Lewis acid in combination with a photoredox sensitizer. This novel proton- and redox-neutral method provides yields of up to 99% and excellent enantioselectivities of up to >99% ee with broad functional group compatibility. Mechanistic investigations suggest that an intermediate rhodium enolate complex acts as a reductive quencher to initiate a radical process with the aryl azides and α-diazo carboxylic esters serving as precursors for nitrogen and carbon-centered radicals, respectively. This is the first report on using aryl azides and α-diazo carboxylic esters as substrates for asymmetric catalysis under photoredox conditions. These reagents have the advantage that molecular nitrogen is the leaving group and sole byproduct in this reaction.

Design and synthesis of N₁-aryl-benzimidazoles 2-substituted as novel HIV-1 non-nucleoside reverse transcriptase inhibitors.

PubMed

Monforte, Anna-Maria; Ferro, Stefania; De Luca, Laura; Lo Surdo, Giuseppa; Morreale, Francesca; Pannecouque, Christophe; Balzarini, Jan; Chimirri, Alba

2014-02-15

A series of novel N1-aryl-2-arylthioacetamido-benzimidazoles were synthesized and evaluated as inhibitors of human immunodeficiency virus type-1 (HIV-1). Some of them proved to be effective in inhibiting HIV-1 replication at submicromolar and nanomolar concentration acting as HIV-1 non-nucleoside RT inhibitors (NNRTIs), with low cytotoxicity. The preliminary structure-activity relationship (SAR) of these new derivatives was discussed and rationalized by docking studies. Copyright © 2014 Elsevier Ltd. All rights reserved.

Determination of absolute configuration in 4-aryl-3, 4-dihydro-2(1H)-pyrimidones by high performance liquid chromatography and CD spectroscopy.

PubMed

Krenn, W; Verdino, P; Uray, G; Faber, K; Kappe, C O

1999-01-01

The absolute configuration of three 4-aryl-3, 4-dihydro-2(1H)-pyrimidones (Biginelli compounds, DHPMs) was established by comparison of the typical circular dichroism (CD) spectra of individual enantiomers with reference samples of known absolute configuration. The enantiomers were obtained by semipreparative separation of racemic mixtures on a Chiralcel OD-H chiral stationary phase. The method was used to establish the enantiopreference of various lipases in biocatalytic kinetic resolution experiments employing activated DHPM esters. Copyright 1999 Wiley-Liss, Inc.

Visible‐Light‐Mediated Selective Arylation of Cysteine in Batch and Flow

PubMed Central

Bottecchia, Cecilia; Rubens, Maarten; Gunnoo, Smita B.; Hessel, Volker; Madder, Annemieke

2017-01-01

Abstract A mild visible‐light‐mediated strategy for cysteine arylation is presented. The method relies on the use of eosin Y as a metal‐free photocatalyst and aryldiazonium salts as arylating agents. The reaction can be significantly accelerated in a microflow reactor, whilst allowing the in situ formation of the required diazonium salts. The batch and flow protocol described herein can be applied to obtain a broad series of arylated cysteine derivatives and arylated cysteine‐containing dipeptides. Moreover, the method was applied to the chemoselective arylation of a model peptide in biocompatible reaction conditions (room temperature, phosphate‐buffered saline (PBS) buffer) within a short reaction time. PMID:28805276

Facile N-Arylation of Amines and Sulfonamides and O-Arylation of Phenols and Arenecarboxylic Acids

PubMed Central

Liu, Zhijian; Larock, Richard C.

2008-01-01

An efficient, transition-metal free procedure for the N-arylation of amines, sulfonamides and carbamates and O-arylation of phenols and carboxylic acids has been achieved by allowing these substrates to react with a variety of o-silylaryl triflates in the presence of CsF. Good to excellent yields of arylated products are obtained under very mild reaction conditions. This chemistry readily tolerates a variety of functional groups. PMID:16599619

Docking and 3-D QSAR studies on indolyl aryl sulfones. Binding mode exploration at the HIV-1 reverse transcriptase non-nucleoside binding site and design of highly active N-(2-hydroxyethyl)carboxamide and N-(2-hydroxyethyl)carbohydrazide derivatives.

PubMed

Ragno, Rino; Artico, Marino; De Martino, Gabriella; La Regina, Giuseppe; Coluccia, Antonio; Di Pasquali, Alessandra; Silvestri, Romano

2005-01-13

Three-dimensional quantitative structure-activity relationship (3-D QSAR) studies and docking simulations were developed on indolyl aryl sulfones (IASs), a class of novel HIV-1 non-nucleoside reverse transcriptase (RT) inhibitors (Silvestri, et al. J. Med. Chem. 2003, 46, 2482-2493) highly active against wild type and some clinically relevant resistant strains (Y181C, the double mutant K103N-Y181C, and the K103R-V179D-P225H strain, highly resistant to efavirenz). Predictive 3-D QSAR models using the combination of GRID and GOLPE programs were obtained using a receptor-based alignment by means of docking IASs into the non-nucleoside binding site (NNBS) of RT. The derived 3-D QSAR models showed conventional correlation (r(2)) and cross-validated (q(2)) coefficients values ranging from 0.79 to 0.93 and from 0.59 to 0.84, respectively. All described models were validated by an external test set compiled from previously reported pyrryl aryl sulfones (Artico, et al. J. Med. Chem. 1996, 39, 522-530). The most predictive 3-D QSAR model was then used to predict the activity of novel untested IASs. The synthesis of six designed derivatives (prediction set) allowed disclosure of new IASs endowed with high anti-HIV-1 activities.

Synthesis and antimycobacterial screening of new thiazolyl-oxazole derivatives.

PubMed

Abhale, Yogita K; Sasane, Amit V; Chavan, Abhijit P; Shekh, Saddam Husen; Deshmukh, Keshav K; Bhansali, Sujit; Nawale, Laxman; Sarkar, Dhiman; Mhaske, Pravin C

2017-05-26

In the present study a series of 4-methyl-2-aryl-5-(2-aryl/benzyl thiazol-4-yl) oxazole (4a-v) have been synthesized and evaluated for their preliminary antitubercular, antimicrobial and cytotoxicity activity. Among all the synthesized compounds, 4v reported comparable activity against dormant M. tuberculosis H 37 Ra and M. bovis BCG strains with respect to standard drug rifampicin. The active compounds from the antitubercular study were further tested for anti-proliferative activity against HeLa, A549 and PANC-1 cell lines using MTT assay and showed no significant cytotoxic activity at the maximum concentration evaluated. Further, the synthesized compounds were found to have potential antibacterial activities with MIC range of 2.1-26.8 μg/mL. High potency, lower cytotoxicity and promising antimycobacterial activity suggested that these compounds could serve as good leads for further optimisation and development. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Evaluating Metabolite-Related DNA Oxidation and Adduct Damage from Aryl Amines Using a Microfluidic ECL Array.

PubMed

Bist, Itti; Bhakta, Snehasis; Jiang, Di; Keyes, Tia E; Martin, Aaron; Forster, Robert J; Rusling, James F

2017-11-21

Damage to DNA from the metabolites of drugs and pollutants constitutes a major human toxicity pathway known as genotoxicity. Metabolites can react with metal ions and NADPH to oxidize DNA or participate in S N 2 reactions to form covalently linked adducts with DNA bases. Guanines are the main DNA oxidation sites, and 8-oxo-7,8-dihydro-2-deoxyguanosine (8-oxodG) is the initial product. Here we describe a novel electrochemiluminescent (ECL) microwell array that produces metabolites from test compounds and measures relative rates of DNA oxidation and DNA adduct damage. In this new array, films of DNA, metabolic enzymes, and an ECL metallopolymer or complex assembled in microwells on a pyrolytic graphite wafer are housed in dual microfluidic chambers. As reactant solution passes over the wells, metabolites form and can react with DNA in the films to form DNA adducts. These adducts are detected by ECL from a RuPVP polymer that uses DNA as a coreactant. Aryl amines also combine with Cu 2+ and NADPH to form reactive oxygen species (ROS) that oxidize DNA. The resulting 8-oxodG was detected selectively by ECL-generating bis(2,2'-bipyridine)-(4-(1,10-phenanthrolin-6-yl)-benzoic acid)Os(II). DNA/enzyme films on magnetic beads were oxidized similarly, and 8-oxodG determined by LC/MS/MS enabled array standardization. The array limit of detection for oxidation was 720 8-oxodG per 10 6 nucleobases. For a series of aryl amines, metabolite-generated DNA oxidation and adduct formation turnover rates from the array correlated very well with rodent 1/TD 50 and Comet assay results.

Ultrafast endothermic transfer of non-radiative exciplex state to radiative excitons in polyfluorene random copolymer for blue electroluminescence

NASA Astrophysics Data System (ADS)

Moghe, Dhanashree A.; Dey, Amrita; Johnson, Kerr; Lu, L.-P.; Friend, Richard H.; Kabra, Dinesh

2018-04-01

We report a blue-emitting random copolymer (termed modified Aryl-F8) consisting of three repeat units of polydioctylfluorene (F8), Aryl-polydioctylfluorene (Aryl-F8), and an aromatic amine comonomer unit, poly(bis-N,Ν'-(4-butylphenyl)-bis-N,N'-phenyl-1,4 phenylenediamine) chemically linked to get an improved charge carrier balance without compromising on the photoluminescence (PL) quantum yield with respect to the Aryl-F8 homo-polymer. The measured photoluminescence quantum efficiency (˜70%) of the blue-emitting polymer is comparable to or greater than the individual monomer units. The time resolved PL spectra from the modified Aryl-F8 are similar to those of Arylated-poly(9,9'-dioctylfluorene-co-bis-N,N'-(4-butylphenyl)-bis-N,N'-phenyl-1,4 phenylenediamine) (PFB) even at a time scale of 100-250 ps, indicating an ultrafast energy transfer from the (Aryl-F8 or F8):Arylated-PFB interface to Arylated-PFB, i.e., endothermic transfer of non-radiative exciplex to a radiative molecular exciton. Furthermore, the presence of non-radiative exciplex is confirmed by the photoluminescence decay profile and temperature dependent PL spectra. The luminance efficiency achieved for the modified Aryl-F8 polymer light-emitting diodes is ˜11 cd A-1 with an external quantum efficiency (EQE) of ˜4.5%, whereas it is 0.05 cd/A with an EQE of ˜0.025% for Aryl-F8. Almost two orders of higher efficiency is achieved due to the improved charge carrier balance from the random copolymer without compromising on the photoluminescence yield.

Palladium-Catalyzed Conversion of Aryl and Vinyl Triflates to Bromides and Chlorides

PubMed Central

Shen, Xiaoqiang; Hyde, Alan M.; Buchwald, Stephen L.

2010-01-01

The palladium-catalyzed conversion of aryl and vinyl triflates to aryl and vinyl halides (bromides and chlorides) has been developed using dialkylbiaryl phosphine ligands. A variety of aryl, heteroaryl and vinyl halides can be prepared via this method in good to excellent yields. PMID:20857936

Feedback control of AHR signalling regulates intestinal immunity.

PubMed

Schiering, Chris; Wincent, Emma; Metidji, Amina; Iseppon, Andrea; Li, Ying; Potocnik, Alexandre J; Omenetti, Sara; Henderson, Colin J; Wolf, C Roland; Nebert, Daniel W; Stockinger, Brigitta

2017-02-09

The aryl hydrocarbon receptor (AHR) recognizes xenobiotics as well as natural compounds such as tryptophan metabolites, dietary components and microbiota-derived factors, and it is important for maintenance of homeostasis at mucosal surfaces. AHR activation induces cytochrome P4501 (CYP1) enzymes, which oxygenate AHR ligands, leading to their metabolic clearance and detoxification. Thus, CYP1 enzymes have an important feedback role that curtails the duration of AHR signalling, but it remains unclear whether they also regulate AHR ligand availability in vivo. Here we show that dysregulated expression of Cyp1a1 in mice depletes the reservoir of natural AHR ligands, generating a quasi AHR-deficient state. Constitutive expression of Cyp1a1 throughout the body or restricted specifically to intestinal epithelial cells resulted in loss of AHR-dependent type 3 innate lymphoid cells and T helper 17 cells and increased susceptibility to enteric infection. The deleterious effects of excessive AHR ligand degradation on intestinal immune functions could be counter-balanced by increasing the intake of AHR ligands in the diet. Thus, our data indicate that intestinal epithelial cells serve as gatekeepers for the supply of AHR ligands to the host and emphasize the importance of feedback control in modulating AHR pathway activation.

2-Aryl-2-nitroacetates as Central Precursors to Aryl Nitromethanes, α-Ketoesters, and α-Amino Acids

PubMed Central

Metz, Alison E.

2013-01-01

Nitroarylacetates are useful small molecular building blocks that act as precursors to α-ketoesters and aryl nitromethanes as well as α-amino acids. Methods were developed that produce each of these compound types in good yields. Two different conditions for decarboxylation are discussed for substrates with neutral and electron-poor aryl groups versus electron-rich aryl groups. For formation of the α-ketoesters, new mild conditions for the Nef disproportionation were identified. PMID:23245626

Pseudoephedrine-Directed Asymmetric α-Arylation of α-Amino Acid Derivatives.

PubMed

Atkinson, Rachel C; Fernández-Nieto, Fernando; Mas Roselló, Josep; Clayden, Jonathan

2015-07-27

Available α-amino acids undergo arylation at their α position in an enantioselective manner on treatment with base of N'-aryl urea derivatives ligated to pseudoephedrine as a chiral auxiliary. In situ silylation and enolization induces diastereoselective migration of the N'-aryl group to the α position of the amino acid, followed by ring closure to a hydantoin with concomitant explulsion of the recyclable auxiliary. The hydrolysis of the hydantoin products provides derivatives of quaternary amino acids. The arylation avoids the use of heavy-metal additives, and is successful with a range of amino acids and with aryl rings of varying electronic character. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Chemoselective Radical Dehalogenation and C-C Bond Formation on Aryl Halide Substrates Using Organic Photoredox Catalysts.

PubMed

Poelma, Saemi O; Burnett, G Leslie; Discekici, Emre H; Mattson, Kaila M; Treat, Nicolas J; Luo, Yingdong; Hudson, Zachary M; Shankel, Shelby L; Clark, Paul G; Kramer, John W; Hawker, Craig J; Read de Alaniz, Javier

2016-08-19

Despite the number of methods available for dehalogenation and carbon-carbon bond formation using aryl halides, strategies that provide chemoselectivity for systems bearing multiple carbon-halogen bonds are still needed. Herein, we report the ability to tune the reduction potential of metal-free phenothiazine-based photoredox catalysts and demonstrate the application of these catalysts for chemoselective carbon-halogen bond activation to achieve C-C cross-coupling reactions as well as reductive dehalogenations. This procedure works both for conjugated polyhalides as well as unconjugated substrates. We further illustrate the usefulness of this protocol by intramolecular cyclization of a pyrrole substrate, an advanced building block for a family of natural products known to exhibit biological activity.

Human Urinary Composition Controls Antibacterial Activity of Siderocalin* ♦

PubMed Central

Shields-Cutler, Robin R.; Crowley, Jan R.; Hung, Chia S.; Stapleton, Ann E.; Aldrich, Courtney C.; Marschall, Jonas; Henderson, Jeffrey P.

2015-01-01

During Escherichia coli urinary tract infections, cells in the human urinary tract release the antimicrobial protein siderocalin (SCN; also known as lipocalin 2, neutrophil gelatinase-associated lipocalin/NGAL, or 24p3). SCN can interfere with E. coli iron acquisition by sequestering ferric iron complexes with enterobactin, the conserved E. coli siderophore. Here, we find that human urinary constituents can reverse this relationship, instead making enterobactin critical for overcoming SCN-mediated growth restriction. Urinary control of SCN activity exhibits wide ranging individual differences. We used these differences to identify elevated urinary pH and aryl metabolites as key biochemical host factors controlling urinary SCN activity. These aryl metabolites are well known products of intestinal microbial metabolism. Together, these results identify an innate antibacterial immune interaction that is critically dependent upon individualistic chemical features of human urine. PMID:25861985

Antimalarial activity of novel 5-aryl-8-aminoquinoline derivatives.

PubMed

Shiraki, Hiroaki; Kozar, Michael P; Melendez, Victor; Hudson, Thomas H; Ohrt, Colin; Magill, Alan J; Lin, Ai J

2011-01-13

In an attempt to separate the antimalarial activity of tafenoquine (3) from its hemolytic side effects in glucose-6-phosphate dehydrogenase (G6PD) deficiency patients, a series of 5-aryl-8-aminoquinoline derivatives was prepared and assessed for antimalarial activities. The new compounds were found metabolically stable in human and mouse microsomal preparations, with t(1/2) > 60 min, and were equal to or more potent than primaquine (2) and 3 against Plasmodium falciparum cell growth. The new agents were more active against the chloroquine (CQ) resistant clone than to the CQ-sensitive clone. Analogues with electron donating groups showed better activity than those with electron withdrawing substituents. Compounds 4bc, 4bd, and 4be showed comparable therapeutic index (TI) to that of 2 and 3, with TI ranging from 5 to 8 based on IC(50) data. The new compounds showed no significant causal prophylactic activity in mice infected with Plasmodium berghei sporozoites, but are substantially less toxic than 2 and 3 in mouse tests.

Docking of oxalyl aryl amino benzoic acid derivatives into PTP1B

PubMed Central

Verma, Neelam; Mittal, Minakshi; Verma, Raman kumar

2008-01-01

Protein Tyrosine Phosphatases (PTPs) that function as negative regulators of the insulin signaling cascade have been identified as novel targets for the therapeutic enhancement of insulin action in insulin resistant disease states. Reducing Protein Tyrosine Phosphatase1B (PTP1B) abundance not only enhances insulin sensitivity and improves glucose metabolism but also protects against obesity induced by high fat feeding. PTP1B inhibitors such as Formylchromone derivatives, 1, 2-Naphthoquinone derivatives and Oxalyl aryl amino benzoic derivatives may eventually find an important clinical role as insulin sensitizers in the management of Type-II Diabetes and metabolic syndrome. We have carried out docking of modified oxalyl aryl amino benzoic acid derivatives into three dimensional structure of PTP1B using BioMed CAChe 6.1. These compounds exhibit good selectivity for PTP1B over most of phosphatases in selectivity panel such as SHP-2, LAR, CD45 and TCPTP found in literature. This series of compounds identified the amino acid residues such as Gly220 and Arg221 are important for achieving specificity via H-bonding interactions. Lipophilic side chain of methionine in modified oxalyl aryl amino benzoic acid derivative [1b (a2, b2, c1, d)] lies in closer vicinity of hydrophobic region of protein consisted of Meth258 and Phe52 in comparison to active ligand. Docking Score in [1b (a2, b2, c1, d)] is -131.740Kcal/mol much better than active ligand score -98.584Kcal/mol. This information can be exploited to design PTP1B specific inhibitors. PMID:19238234

Structure-activity relationships of amide-phosphonate derivatives as inhibitors of the human soluble epoxide hydrolase.

PubMed

Kim, In-Hae; Park, Yong-Kyu; Nishiwaki, Hisashi; Hammock, Bruce D; Nishi, Kosuke

2015-11-15

Structure-activity relationships of amide-phosphonate derivatives as inhibitors of the human soluble epoxide hydrolase (sEH) were investigated. First, a series of alkyl or aryl groups were substituted on the carbon alpha to the phosphonate function in amide compounds to see whether substituted phosphonates can act as a secondary pharmacophore. A tert-butyl group (16) on the alpha carbon was found to yield most potent inhibition on the target enzyme. A 4-50-fold drop in inhibition was induced by other substituents such as aryls, substituted aryls, cycloalkyls, and alkyls. Then, the modification of the O-substituents on the phosphonate function revealed that diethyl groups (16 and 23) were preferable for inhibition to other longer alkyls or substituted alkyls. In amide compounds with the optimized diethylphosphonate moiety and an alkyl substitution such as adamantane (16), tetrahydronaphthalene (31), or adamantanemethane (36), highly potent inhibitions were gained. In addition, the resulting potent amide-phosphonate compounds had reasonable water solubility, suggesting that substituted phosphonates in amide inhibitors are effective for both inhibition potency on the human sEH and water solubility as a secondary pharmacophore. Copyright © 2015 Elsevier Ltd. All rights reserved.

Metformin suppresses CYP1A1 and CYP1B1 expression in breast cancer cells by down-regulating aryl hydrocarbon receptor expression

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

Do, Minh Truong; Kim, Hyung Gyun; Tran, Thi Thu Phuong

2014-10-01

Induction of cytochrome P450 (CYP) 1A1 and CYP1B1 by environmental xenobiotic chemicals or endogenous ligands through the activation of the aryl hydrocarbon receptor (AhR) has been implicated in a variety of cellular processes related to cancer, such as transformation and tumorigenesis. Here, we investigated the effects of the anti-diabetes drug metformin on expression of CYP1A1 and CYP1B1 in breast cancer cells under constitutive and inducible conditions. Our results indicated that metformin down-regulated the expression of CYP1A1 and CYP1B1 in breast cancer cells under constitutive and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-induced conditions. Down-regulation of AhR expression was required for metformin-mediated decreases in CYP1A1 andmore » CYP1B1 expression, and the metformin-mediated CYP1A1 and CYP1B1 reduction is irrelevant to estrogen receptor α (ERα) signaling. Furthermore, we found that metformin markedly down-regulated Sp1 protein levels in breast cancer cells. The use of genetic and pharmacological tools revealed that metformin-mediated down-regulation of AhR expression was mediated through the reduction of Sp1 protein. Metformin inhibited endogenous AhR ligand-induced CYP1A1 and CYP1B1 expression by suppressing tryptophan-2,3-dioxygenase (TDO) expression in MCF-7 cells. Finally, metformin inhibits TDO expression through a down-regulation of Sp1 and glucocorticoid receptor (GR) protein levels. Our findings demonstrate that metformin reduces CYP1A1 and CYP1B1 expression in breast cancer cells by down-regulating AhR signaling. Metformin would be able to act as a potential chemopreventive agent against CYP1A1 and CYP1B1-mediated carcinogenesis and development of cancer. - Graphical abstract: Schematic of the CYP1A1 and CYP1B1 gene regulation by metformin. - Highlights: • Metformin inhibits CYP1A1 and CYP1B1 expression. • Metformin down-regulates the AhR signaling. • Metformin reduces Sp1 protein expression. • Metformin suppresses TDO expression.« less

40 CFR 721.6220 - Aryl sulfonate of a fatty acid mixture, polyamine condensate.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Aryl sulfonate of a fatty acid mixture... Specific Chemical Substances § 721.6220 Aryl sulfonate of a fatty acid mixture, polyamine condensate. (a... generically as an aryl sulfonate of a fatty acid mixture, polyamine condensate (PMN P-91-584) is subject to...

40 CFR 721.9597 - Salt of a substituted sulfonated aryl azo compound (generic).

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Salt of a substituted sulfonated aryl... New Uses for Specific Chemical Substances § 721.9597 Salt of a substituted sulfonated aryl azo... substance identified generically as salt of a substituted sulfonated aryl azo compound (PMN P-00-0094) is...

40 CFR 721.9597 - Salt of a substituted sulfonated aryl azo compound (generic).

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Salt of a substituted sulfonated aryl... New Uses for Specific Chemical Substances § 721.9597 Salt of a substituted sulfonated aryl azo... substance identified generically as salt of a substituted sulfonated aryl azo compound (PMN P-00-0094) is...

40 CFR 721.6220 - Aryl sulfonate of a fatty acid mixture, polyamine condensate.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Aryl sulfonate of a fatty acid mixture... Specific Chemical Substances § 721.6220 Aryl sulfonate of a fatty acid mixture, polyamine condensate. (a... generically as an aryl sulfonate of a fatty acid mixture, polyamine condensate (PMN P-91-584) is subject to...

Visible light catalyzed methylsulfoxidation of (het)aryl diazonium salts using DMSO.

PubMed

Pramanik, Mukund M D; Rastogi, Namrata

2016-06-30

The visible light catalyzed methylsulfoxidation of (het)aryl diazonium salts using DMSO is illustrated. This is the first example of DMSO being used as the source of the methylsulfinyl group. The procedure tolerates a wide range of functional groups on (het)aryl diazonium salts and provides aryl methyl sulfoxides in excellent yields under mild reaction conditions.

Regioselective copper-catalyzed N(1)-(hetero)arylation of protected histidine.

PubMed

Sharma, Krishna K; Mandloi, Meenakshi; Jain, Rahul

2016-09-26

We report regioselective N(1)-arylation of protected histidine using copper(i) iodide as a catalyst, trans-N,N'-dimethylcyclohexane-1,2-diamine as a ligand and readily available aryl iodides as coupling partners under microwave irradiation at 130 °C for 40 min. The reaction provides rapid access to electron-donating, electron-withdrawing and bulky group substituted N-arylated histidines in high yields, including previously inaccessible N-heteroaryl histidines. These N(1)-(hetero)aryl histidines are promising building blocks in peptide-based drug design and discovery.

β-Selective C-H arylation of pyrroles leading to concise syntheses of lamellarins C and I.

PubMed

Ueda, Kirika; Amaike, Kazuma; Maceiczyk, Richard M; Itami, Kenichiro; Yamaguchi, Junichiro

2014-09-24

The first general β-selective C-H arylation of pyrroles has been developed by using a rhodium catalyst. This C-H arylation reaction, which is retrosynthetically straightforward but results in unusual regioselectivity, could result in de novo syntheses of pyrrole-derived natural products and pharmaceuticals. As such, we have successfully synthesized polycyclic marine pyrrole alkaloids, lamellarins C and I, by using this β-selective arylation of pyrroles with aryl iodides (C-H/C-I coupling) and a new double C-H/C-H coupling as key steps.

Transcript variations, phylogenetic tree and chromosomal localization of porcine aryl hydrocarbon receptor (AhR) and AhR nuclear translocator (ARNT) genes.

PubMed

Sadowska, Agnieszka; Paukszto, Lukasz; Nynca, Anna; Szczerbal, Izabela; Orlowska, Karina; Swigonska, Sylwia; Ruszkowska, Monika; Molcan, Tomasz; Jastrzebski, Jan P; Panasiewicz, Grzegorz; Ciereszko, Renata E

2017-03-01

Aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor best known for mediating xenobiotic-induced toxicity. AhR requires aryl hydrocarbon receptor nuclear translocator (ARNT) to form an active transcription complex and promote the activation of genes which have dioxin responsive element in their regulatory regions. The present study was performed to determine the complete cDNA sequences of porcine AhR and ARNT genes and their chromosomal localization. Total RNA from porcine livers were used to obtain the sequence of the entire porcine transcriptome by next-generation sequencing (NGS; lllumina HiSeq2500). In addition, both, in silico analysis and fluorescence in situ hybridization (FISH) were used to determine chromosomal localization of porcine AhR and ARNT genes. In silico analysis of nucleotide sequences showed that there were two transcript variants of AhR and ARNT genes in the pig. In addition, computer analysis revealed that AhR gene in the pig is located on chromosome 9 and ARNT on chromosome 4. The results of FISH experiment confirmed the localization of porcine AhR and ARNT genes. In the present study, for the first time, the full cDNAs of AhR and ARNT were demonstrated in the pig. In future, it would be interesting to determine the tissue distribution of AhR and ARNT transcript variants in the pig and to test whether these variants are associated with different biological functions and/or different activation pathways.

Structure-activity relationship of new antimalarial 1-aryl-3-susbtituted propanol derivatives: Synthesis, preliminary toxicity profiling, parasite life cycle stage studies, target exploration, and targeted delivery.

PubMed

Quiliano, Miguel; Pabón, Adriana; Moles, Ernest; Bonilla-Ramirez, Leonardo; Fabing, Isabelle; Fong, Kim Y; Nieto-Aco, Diego A; Wright, David W; Pizarro, Juan C; Vettorazzi, Ariane; López de Cerain, Adela; Deharo, Eric; Fernández-Busquets, Xavier; Garavito, Giovanny; Aldana, Ignacio; Galiano, Silvia

2018-05-25

Design, synthesis, structure-activity relationship, cytotoxicity studies, in silico drug-likeness, genotoxicity screening, and in vivo studies of new 1-aryl-3-substituted propanol derivatives led to the identification of nine compounds with promising in vitro (55, 56, 61, 64, 66, and 70-73) and in vivo (66 and 72) antimalarial profiles against Plasmodium falciparum and Plasmodium berghei. Compounds 55, 56, 61, 64, 66 and 70-73 exhibited potent antiplasmodial activity against chloroquine-resistant strain FCR-3 (IC 50 s < 0.28 μM), and compounds 55, 56, 64, 70, 71, and 72 showed potent biological activity in chloroquine-sensitive and multidrug-resistant strains (IC 50 s < 0.7 μM for 3D7, D6, FCR-3 and C235). All of these compounds share appropriate drug-likeness profiles and adequate selectivity indexes (77 < SI < 184) as well as lack genotoxicity. In vivo efficacy tests in a mouse model showed compounds 66 and 72 to be promising candidates as they exhibited significant parasitemia reductions of 96.4% and 80.4%, respectively. Additional studies such as liver stage and sporogony inhibition, target exploration of heat shock protein 90 of P. falciparum, targeted delivery by immunoliposomes, and enantiomer characterization were performed and strongly reinforce the hypothesis of 1-aryl-3-substituted propanol derivatives as promising antimalarial compounds. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

Synthesis of 3,4-dihydro-1,8-naphthyridin-2(1H)-ones via microwave-activated inverse electron-demand Diels–Alder reactions

PubMed Central

Fadel, Salah; Hajbi, Youssef; Khouili, Mostafa; Lazar, Said

2014-01-01

Summary Substituted 3,4-dihydro-1,8-naphthyridin-2(1H)-ones have been synthesized with the inverse electron-demand Diels–Alder reaction from 1,2,4-triazines bearing an acylamino group with a terminal alkyne side chain. Alkynes were first subjected to the Sonogashira cross-coupling reaction with aryl halides, the product of which then underwent an intramolecular inverse electron-demand Diels–Alder reaction to yield 5-aryl-3,4-dihydro-1,8-naphthyridin-2(1H)-ones by an efficient synthetic route. PMID:24605148

Divergent strategy for the synthesis of alpha-aryl-substituted fosmidomycin analogues.

PubMed

Devreux, Vincent; Wiesner, Jochen; Jomaa, Hassan; Rozenski, Jef; Van der Eycken, Johan; Van Calenbergh, Serge

2007-05-11

Fosmidomycin is the first representative of a new class of antimalarial drugs acting through inhibition of 1-deoxy-D-xylulose 5-phosphate (DOXP) reductoisomerase (DXR), an essential enzyme in the non-mevalonate pathway for the synthesis of isoprenoids. This work describes a divergent strategy for the synthesis of a series of alpha-aryl-substituted fosmidomycin analogues, featuring a palladium-catalyzed Stille coupling as the key step. An alpha-(4-cyanophenyl)fosmidomycin analogue emerged as the most potent analogue in the present series. Its antimalarial activity clearly surpasses that of the reference compound fosmidomycin.

Synthesis of 3,4-dihydro-1,8-naphthyridin-2(1H)-ones via microwave-activated inverse electron-demand Diels-Alder reactions.

PubMed

Fadel, Salah; Hajbi, Youssef; Khouili, Mostafa; Lazar, Said; Suzenet, Franck; Guillaumet, Gérald

2014-01-01

Substituted 3,4-dihydro-1,8-naphthyridin-2(1H)-ones have been synthesized with the inverse electron-demand Diels-Alder reaction from 1,2,4-triazines bearing an acylamino group with a terminal alkyne side chain. Alkynes were first subjected to the Sonogashira cross-coupling reaction with aryl halides, the product of which then underwent an intramolecular inverse electron-demand Diels-Alder reaction to yield 5-aryl-3,4-dihydro-1,8-naphthyridin-2(1H)-ones by an efficient synthetic route.

Synthesis, structures, electrochemical studies and antioxidant activity of 5-aryl-4-oxo-3,4,5,8-tetrahydropyrido[2,3-d]pyrimidine-7-carboxylic acids

NASA Astrophysics Data System (ADS)

Quiroga, Jairo; Romo, Pablo E.; Ortiz, Alejandro; Isaza, José Hipólito; Insuasty, Braulio; Abonia, Rodrigo; Nogueras, Manuel; Cobo, Justo

2016-09-01

The synthesis of 5-aryl-4-oxo-3,4,5,8-tetrahydropyrido[2,3-d]pyrimidine-7-carboxylic acids 3 from the reaction of 6-aminopyrimidines 1 with arylidene derivatives of pyruvic acid 2 under microwave and ultrasound irradiation is described. The orientation of cyclization process was determined by NMR measurements. The methodology provides advantages such as high yields and friendly to the environment without the use of solvents. The antioxidant properties, DPPH free radical scavenging, ORAC, and anodic potential oxidation of the new pyridopyrimidines were studied.

Reaction of the antitumor antibiotic olivomycin I with aryl diazonium salts. Synthesis, cytotoxic and antiretroviral potency of 5-aryldiazenyl-6-O-deglycosyl derivatives of olivomycin I.

PubMed

Tevyashova, Anna N; Olsufyeva, Eugenia N; Turchin, Konstantin F; Balzarini, Jan; Bykov, Eugenyi E; Dezhenkova, Lyubov G; Shtil, Alexander A; Preobrazhenskaya, Maria N

2009-07-15

The azo coupling of the antibiotic olivomycin I (1) with aryl diazonium tetrafluoroborates produced 5-aryldiazenyl-6-O-deglycosyl derivatives of 1. The structures of new compounds were confirmed by (1)H NMR and mass spectrometry analysis. A quantum-chemical study was performed to analyze the possible directions of electrophilic substitution of 1 and the easiness of 6-O-disaccharide hydrolysis in the course of azo coupling. The antiproliferative and anti-retroviral activities of novel derivatives were studied.

Synthesis of new substituted azetidinoyl and thiazolidinoyl-1,3,4-thiadiazino (6,5-b) indoles as promising anti-inflammatory agents.

PubMed

Bhati, Sudhir Kumar; Kumar, Ashok

2008-11-01

Various N-({5-[(arylmethylene)amino]-1,3,4-thiadiazol-2-yl}methyl) [1,3,4] thiadiazino[6,5-b]indol-3-amine (6a-6h), 2-aryl-3-{5-[([1,3,4] thiadiazino[6,5-b]indol-3-ylamino)methyl]-1,3,4-thiadiazol-2-yl}-1,3-thiazolidin-4-one (7a-7h), and 3-chloro-4-aryl-1-{5-[{[1,3,4]thiadiazino[6,5-b]indol-3-ylamino]methyl]-1,3,4-thiadiazol-2-yl}azetidin-2-one (8a-8h) have been synthesized in the present study. The structure of these newly synthesized compounds were confirmed by their analytical and spectral data. These compounds were also evaluated for their anti-inflammatory, ulcerogenic and analgesic activities. Compound 8g has shown most active anti-inflammatory and analgesic activities with better ulcerogenic activity than phenylbutazone, while this compound was found to be associated with lesser degree of anti-inflammatory and analgesic activities as compared to indomethacin.

Chemoselective N-arylation of aminobenzamides via copper catalysed Chan-Evans-Lam reactions.

PubMed

Liu, Shuai; Zu, Weisai; Zhang, Jinli; Xu, Liang

2017-11-15

Chemoselective N-arylation of unprotected aminobenzamides was achieved via Cu-catalysed Chan-Evans-Lam cross-coupling with aryl boronic acids for the first time. Simple copper catalysts enable the selective arylation of amino groups in ortho/meta/para-aminobenzamides under open-flask conditions. The reactions were scalable and compatible with a wide range of functional groups.

Functionalized polyfluorenes for use in optoelectronic devices

DOEpatents

Chichak, Kelly Scott [Clifton Park, NY; Lewis, Larry Neil [Scotia, NY; Cella, James Anthony [Clifton Park, NY; Shiang, Joseph John [Niskayuna, NY

2011-11-08

The present invention relates to process comprising reacting a polyfluorenes comprising at least one structural group of formula I ##STR00001## with an iridium (III) compound of formula II ##STR00002## wherein R.sup.1 and R.sup.2 are independently alkyl, substituted alkyl, aryl, substituted aryl or a combination thereof; R.sup.5is H or CHO; R.sup.3 and R.sup.4 are independently hydrogen, alkyl, substituted alkyl, aryl, substituted aryl or a combination thereof; R.sup.11 and R.sup.12 taken together form a substituted or unsubstituted monocyclic or bicyclic heteroaromatic ring; R.sup.13 is independently at each occurrence halo, nitro, hydroxy, amino, alkyl, aryl, arylalkyl, alkoxy, substituted alkoxy, substituted alkyl, substituted aryl, or substituted arylalkyl; Ar is aryl, heteroaryl, substituted aryl, substituted heteroaryl, or a combination thereof; X is selected from a direct bond, alky, substituted alkyl, and combinations thereof; Y is CHO or NH.sub.2; Z is CHO or NH.sub.2 where Z does not equal Y; and p is 0, 1 or 2. The invention also relates to the polyfluorenes, which are products of the reaction, and the use of the polyfluorenes in optoelectronic devices.

Mild and selective base-free C–H arylation of heteroarenes: experiment and computation† †Electronic supplementary information (ESI) available. See DOI: 10.1039/c6sc02595a Click here for additional data file.

PubMed Central

Gemoets, Hannes P. L.; Kalvet, Indrek; Nyuchev, Alexander V.; Erdmann, Nico; Hessel, Volker

2017-01-01

A mild and selective C–H arylation strategy for indoles, benzofurans and benzothiophenes is described. The arylation method engages aryldiazonium salts as arylating reagents in equimolar amounts. The protocol is operationally simple, base free, moisture tolerant and air tolerant. It utilizes low palladium loadings (0.5 to 2.0 mol% Pd), short reaction times, green solvents (EtOAc/2-MeTHF or MeOH) and is carried out at room temperature, providing a broad substrate scope (47 examples) and excellent selectivity (C-2 arylation for indoles and benzofurans, C-3 arylation for benzothiophenes). Mechanistic experiments and DFT calculations support a Heck–Matsuda type coupling mechanism. PMID:28451243

6-shogaol, a major compound in ginger, induces aryl hydrocarbon receptor-mediated transcriptional activity and gene expression.

PubMed

Yoshida, Kazutaka; Satsu, Hideo; Mikubo, Ayano; Ogiwara, Haru; Yakabe, Takafumi; Inakuma, Takahiro; Shimizu, Makoto

2014-06-18

Xenobiotics are usually detoxified by drug-metabolizing enzymes and excreted from the body. The expression of many of drug-metabolizing enzymes is regulated by the aryl hydrocarbon receptor (AHR). Some substances in vegetables have the potential to be AHR ligands. To search for vegetable components that exhibit AHR-mediated transcriptional activity, we assessed the activity of vegetable extracts and identified the active compounds using the previously established stable AHR-responsive HepG2 cell line. Among the hot water extracts of vegetables, the highest activity was found in ginger. The ethyl acetate fraction of the ginger hot water extract remarkably induced AHR-mediated transcriptional activity, and the major active compound was found to be 6-shogaol. Subsequently, the mRNA levels of AHR-targeting drug-metabolizing enzymes (CYP1A1, UGT1A1, and ABCG 2) and the protein level of CYP1A1 in HepG2 cells were shown to be increased by 6-shogaol. This is the first report that 6-shogaol can regulate the expression of detoxification enzymes by AHR activation.

A Model for Aryl Hydrocarbon Receptor-Activated Gene Expression Shows Potency and Efficacy Changes and Predicts Squelching Due to Competition for Transcription Co-Activators

PubMed Central

Simon, Ted W.; Budinsky, Robert A.; Rowlands, J. Craig

2015-01-01

A stochastic model of nuclear receptor-mediated transcription was developed based on activation of the aryl hydrocarbon receptor (AHR) by 2,3,7,8-tetrachlorodibenzodioxin (TCDD) and subsequent binding the activated AHR to xenobiotic response elements (XREs) on DNA. The model was based on effects observed in cells lines commonly used as in vitro experimental systems. Following ligand binding, the AHR moves into the cell nucleus and forms a heterodimer with the aryl hydrocarbon nuclear translocator (ARNT). In the model, a requirement for binding to DNA is that a generic coregulatory protein is subsequently bound to the AHR-ARNT dimer. Varying the amount of coregulator available within the nucleus altered both the potency and efficacy of TCDD for inducing for transcription of CYP1A1 mRNA, a commonly used marker for activation of the AHR. Lowering the amount of available cofactor slightly increased the EC50 for the transcriptional response without changing the efficacy or maximal response. Further reduction in the amount of cofactor reduced the efficacy and produced non-monotonic dose-response curves (NMDRCs) at higher ligand concentrations. The shapes of these NMDRCs were reminiscent of the phenomenon of squelching. Resource limitations for transcriptional machinery are becoming apparent in eukaryotic cells. Within single cells, nuclear receptor-mediated gene expression appears to be a stochastic process; however, intercellular communication and other aspects of tissue coordination may represent a compensatory process to maintain an organism’s ability to respond on a phenotypic level to various stimuli within an inconstant environment. PMID:26039703

A novel dihydropyridine with 3-aryl meta-hydroxyl substitution blocks L-type calcium channels in rat cardiomyocytes.

PubMed

Galvis-Pareja, David; Zapata-Torres, Gerald; Hidalgo, Jorge; Ayala, Pedro; Pedrozo, Zully; Ibarra, Cristián; Diaz-Araya, Guillermo; Hall, Andrew R; Vicencio, Jose Miguel; Nuñez-Vergara, Luis; Lavandero, Sergio

2014-08-15

Dihydropyridines are widely used for the treatment of several cardiac diseases due to their blocking activity on L-type Ca(2+) channels and their renowned antioxidant properties. We synthesized six novel dihydropyridine molecules and performed docking studies on the binding site of the L-type Ca(2+) channel. We used biochemical techniques on isolated adult rat cardiomyocytes to assess the efficacy of these molecules on their Ca(2+) channel-blocking activity and antioxidant properties. The Ca(2+) channel-blocking activity was evaluated by confocal microscopy on fluo-3AM loaded cardiomyocytes, as well as using patch clamp experiments. Antioxidant properties were evaluated by flow cytometry using the ROS sensitive dye 1,2,3 DHR. Our docking studies show that a novel compound with 3-OH substitution inserts into the active binding site of the L-type Ca(2+) channel previously described for nitrendipine. In biochemical assays, the novel meta-OH group in the aryl in C4 showed a high blocking effect on L-type Ca(2+) channel as opposed to para-substituted compounds. In the tests we performed, none of the molecules showed antioxidant properties. Only substitutions in C2, C3 and C5 of the aryl ring render dihydropyridine compounds with the capacity of blocking LTCC. Based on our docking studies, we postulate that the antioxidant activity requires a larger group than the meta-OH substitution in C2, C3 or C5 of the dihydropyridine ring. Copyright © 2014 Elsevier Inc. All rights reserved.

Stereospecific Palladium-Catalyzed C-H Arylation of Pyroglutamic Acid Derivatives at the C3 Position Enabled by 8-Aminoquinoline as a Directing Group.

PubMed

Verho, Oscar; Maetani, Micah; Melillo, Bruno; Zoller, Jochen; Schreiber, Stuart L

2017-09-01

An efficient and stereospecific Pd-catalyzed protocol for the C-H arylation of pyroglutamic acid derivatives that uses 8-aminoquinoline as a directing group is described. The reaction was shown to proceed efficiently with a variety of aryl and heteroaryl iodides bearing different functional groups, giving C3-arylated cis products in good to high yields. Removal of the 8-aminoquinoline unit from these C-H arylation products enables access to synthetically useful cis and trans pyroglutamic acid-based building blocks.

1-[(3-Aryloxy-3-aryl)propyl]-1H-imidazoles, new imidazoles with potent activity against Candida albicans and dermatophytes. Synthesis, structure-activity relationship, and molecular modeling studies.

PubMed

La Regina, Giuseppe; D'Auria, Felicia Diodata; Tafi, Andrea; Piscitelli, Francesco; Olla, Stefania; Caporuscio, Fabiana; Nencioni, Lucia; Cirilli, Roberto; La Torre, Francesco; De Melo, Nadja Rodrigues; Kelly, Steven L; Lamb, David C; Artico, Marino; Botta, Maurizio; Palamara, Anna Teresa; Silvestri, Romano

2008-07-10

New 1-[(3-aryloxy-3-aryl)propyl]-1 H-imidazoles were synthesized and evaluated against Candida albicans and dermatophytes in order to develop structure-activity relationships (SARs). Against C. albicans the new imidazoles showed minimal inhibitory concentrations (MICs) comparable to those of ketoconazole, miconazole, and econazole, and were more potent than fluconazole. Several derivatives ( 10, 12, 14, 18- 20, 24, 28, 29, 30, and 34) turned out to be potent inhibitors of C. albicans strains resistant to fluconazole, with MIC values less than 10 microg/mL. Against dermatophytes strains, compounds 20, 25, and 33 (MIC

Comparison of Nootropic and Neuroprotective Features of Aryl-Substituted Analogs of Gamma-Aminobutyric Acid.

PubMed

Tyurenkov, I N; Borodkina, L E; Bagmetova, V V; Berestovitskaya, V M; Vasil'eva, O S

2016-02-01

GABA analogs containing phenyl (phenibut) or para-chlorophenyl (baclofen) substituents demonstrated nootropic activity in a dose of 20 mg/kg: they improved passive avoidance conditioning, decelerated its natural extinction, and exerted antiamnestic effect on the models of amnesia provoked by scopolamine or electroshock. Tolyl-containing GABA analog (tolibut, 20 mg/kg) exhibited antiamnestic activity only on the model of electroshock-induced amnesia. Baclofen and, to a lesser extent, tolibut alleviated seizures provoked by electroshock, i.e. both agents exerted anticonvulsant effect. All examined GABA aryl derivatives demonstrated neuroprotective properties on the maximum electroshock model: they shortened the duration of coma and shortened the period of spontaneous motor activity recovery. In addition, these agents decreased the severity of passive avoidance amnesia and behavioral deficit in the open field test in rats exposed to electroshock. The greatest neuroprotective properties were exhibited by phenyl-containing GABA analog phenibut.

Synthesis, spectral characterization and catalytic activity of Co(II) complexes of drugs: crystal structure of Co(II)-trimethoprim complex.

PubMed

Madhupriya, Selvaraj; Elango, Kuppanagounder P

2014-01-24

New Co(II) complexes with drugs such as trimethoprim (TMP), cimetidine (CTD), niacinamide (NAM) and ofloxacin (OFL) as ligands were synthesized. The complexes were characterized by analytical analysis, various spectral techniques such as FT-IR, UV-Vis, magnetic measurements and molar conductivity. The magnetic susceptibility results coupled with the electronic spectra suggested a tetrahedral geometry for the complexes. The coordination mode of trimethoprim ligand and geometry of the complex were confirmed by single crystal X-ray studies. In this complex the metal ion possesses a tetrahedral geometry with two nitrogen atom from two TMP ligands and two chloride ions coordinated to it. The catalytic activity of the complexes in aryl-aryl coupling reaction was screened and the results indicated that among the four complexes [Co(OFL)Cl(H2O)] exhibited excellent catalytic activity. Copyright © 2013 Elsevier B.V. All rights reserved.

Aryl Ketone Synthesis via Tandem Orthoplatinated Triarylphosphite-Catalyzed Addition Reactions of Arylboronic Acids with Aldehydes Followed by Oxidation

PubMed Central

Liao, Yuan-Xi; Hu, Qiao-Sheng

2010-01-01

Tandem orthoplatinated triarylphosphite-catalyzed addition reactions of arylboronic acids with aldehydes followed by oxidation to yield aryl ketones is described. 3-Pentanone was identified as a suitable oxidant for the tandem aryl ketone formation reaction. By using microwave energy, aryl ketones were obtained in high yields with the catalyst loading as low as 0.01%. PMID:20849092

Severe Liver Cirrhosis Markedly Reduces AhR-Mediated Induction of Cytochrome P450 in Rats by Decreasing the Transcription of Target Genes

PubMed Central

Floreani, Maura; De Martin, Sara; Gabbia, Daniela; Barbierato, Massimo; Nassi, Alberto; Mescoli, Claudia; Orlando, Rocco; Bova, Sergio; Angeli, Paolo; Gola, Elisabetta; Sticca, Antonietta; Palatini, Pietro

2013-01-01

Although the induction of cytochrome P450 (CYP) has long been investigated in patients with cirrhosis, the question whether liver dysfunction impairs the response to CYP inducers still remains unresolved. Moreover, the mechanism underlying the possible effect of cirrhosis on induction has not been investigated. Since ethical constraints do not permit methodologically rigorous studies in humans, this question was addressed by investigating the effect of the prototypical inducer benzo[a]pyrene (BP) on CYP1A1 and CYP1A2 in cirrhotic rats stratified according to the severity of liver dysfunction. We simultaneously assessed mRNA level, protein expression and enzymatic activity of the CYP1A enzymes, as well as mRNA and protein expressions of the aryl hydrocarbon receptor (AhR), which mediates the BP effect. Basal mRNA and protein expressions of CYP1A1 were virtually absent in both healthy and cirrhotic rats. On the contrary, CYP1A2 mRNA, protein and enzyme activity were constitutively present in healthy rats and decreased significantly as liver function worsened. BP treatment markedly increased the concentrations of mRNA and immunodetectable protein, and the enzymatic activities of both CYP1A enzymes to similar levels in healthy and non-ascitic cirrhotic rats. Induced mRNA levels, protein expressions and enzymatic activities of both CYPs were much lower in ascitic rats and were proportionally reduced. Both constitutive and induced protein expressions of AhR were significantly lower in ascitic than in healthy rats. These results indicate that the inducibility of CYP1A enzymes is well preserved in compensated cirrhosis, whereas it is markedly reduced when liver dysfunction becomes severe. Induction appears to be impaired at the transcriptional level, due to the reduced expression of AhR, which controls the transcription of CYP1A genes. PMID:23626760

Aryl-modified graphene quantum dots with enhanced photoluminescence and improved pH tolerance

NASA Astrophysics Data System (ADS)

Luo, Peihui; Ji, Zhe; Li, Chun; Shi, Gaoquan

2013-07-01

Chemical modification is an important technique to modulate the chemical and optical properties of graphene quantum dots (GQDs). In this paper, we report a versatile diazonium chemistry method to graft aryl groups including phenyl, 4-carboxyphenyl, 4-sulfophenyl and 5-sulfonaphthyl to GQDs via Gomberg-Bachmann reaction. The aryl-modified GQDs are nanocrystals with lateral dimensions in the range of 2-4 nm and an average thickness lower than 1 nm. Upon chemical modification with aryl groups, the photoluminescence (PL) bands of GQDs were tuned in the range of 418 and 447 nm, and their fluorescence quantum yields (QYs) were increased for up to about 6 times. Furthermore, the aryl-modified GQDs exhibited stable PL (both intensity and peak position) in a wide pH window of 1-11. The mechanism of improving the PL properties of GQDs by aryl-modification was also discussed.Chemical modification is an important technique to modulate the chemical and optical properties of graphene quantum dots (GQDs). In this paper, we report a versatile diazonium chemistry method to graft aryl groups including phenyl, 4-carboxyphenyl, 4-sulfophenyl and 5-sulfonaphthyl to GQDs via Gomberg-Bachmann reaction. The aryl-modified GQDs are nanocrystals with lateral dimensions in the range of 2-4 nm and an average thickness lower than 1 nm. Upon chemical modification with aryl groups, the photoluminescence (PL) bands of GQDs were tuned in the range of 418 and 447 nm, and their fluorescence quantum yields (QYs) were increased for up to about 6 times. Furthermore, the aryl-modified GQDs exhibited stable PL (both intensity and peak position) in a wide pH window of 1-11. The mechanism of improving the PL properties of GQDs by aryl-modification was also discussed. Electronic supplementary information (ESI) available: Fluorescence quantum yield measurements, estimation of grafting ratio, TEM images, FTIR spectra, PL spectra and zeta potentials. See DOI: 10.1039/c3nr02156d

Activation of AhR-mediated toxicity pathway by emerging pollutants polychlorinated diphenyl sulfides

EPA Science Inventory

Polychlorinated diphenyl sulfides (PCDPSs) are a group of environmental pollutants for which limited toxicological information is available. This study tested the hypothesis that PCDPSs could activate the mammalian aryl hydrocarbon receptor (AhR) mediated toxicity pathways. Eight...

Synthesis of novel antimicrobial aryl himachalene derivatives from naturally occurring himachalenes

PubMed Central

Chaudhary, Abha; Sood, Swati; Das, Pralay; Kaur, Pushpinder; Mahajan, Isha; Gulati, Arvind; Singh, Bikram

2014-01-01

Five new 2,9,9-trimethyl-6,7,8,9-tetrahydro-benzocyclohepten-5-ylidene-amine derivatives (16a-16e) were synthesized from α-dehydro-ar-himachalene (11) that was originally prepared from an isomeric mixture of α, β and γ himachalenes (10), the abundant sesquiterpenes of Cedrus deodara essential oil. In addition, different aryl himachalenes derivatives (9, 12, 14 and 15) were also formed from 11. The structures of the synthesized compounds were confirmed on the basis of their NMR, IR and mass spectral data. The prepared compounds were tested against a group of sixteen organisms including gram positive and gram negative bacterial and fungal strains. The introduction of a series of substituted imine groups into aryl himachalenes at 5th position (16a-16e) enhanced antimicrobial activity as compared to the aromatized derivatives (9, 12, 14 and 15) against gram-positive bacteria Bacillus subtilis, Micrococcus luteus and Staphylococcus aureus, and mycotoxigenic fungi Aspergillus parasiticus, A. ochraceous and A. sydowii. graphical Abstract, Figure 1(Fig. 1) PMID:26417335

Chemical degradation mechanisms of membranes for alkaline membrane fuel cells

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

Choe, Yoong-Kee; Henson, Neil J.; Kim, Yu Seung

2015-12-31

Chemical degradation mechanisms of membranes for alkaline membrane fuel cells have been investigated using density functional theory (DFT). We have elucidated that the aryl-ether moiety of membranes is one of the weakest site against attack of hydroxide ions. The results of DFT calculations for hydroxide initiated aryl-ether cleavage indicated that the aryl-ether cleavage occurred prior to degradation of cationic functional group. Such a weak nature of the aryl-ether group arises from the electron deficiency of the aryl group as well as the low bond dissociation energy. The DFT results suggests that removal of the aryl-ether group in the membrane shouldmore » enhance the stability of membranes under alkaline conditions. In fact, an ether fee poly(phenylene) membrane exhibits excellent stability against the attack from hydroxide ions.« less

Sudan III dye strongly induces CYP1A1 mRNA expression in HepG2 cells.

PubMed

Ohno, Marumi; Ikenaka, Yoshinori; Ishizuka, Mayumi

2012-01-01

Sudan dyes possess a high affinity to the aryl hydrocarbon receptor (AHR) and potently induce its target genes, such as cytochrome P450 (CYP) 1A1, through unknown mechanisms. We investigated a detailed event occurring in cells after binding of Sudan dye to AHR in HepG2 cells. Treatment with 10 µM Sudan III caused rapid translocation of AHR into the nucleus and increased expression levels of human CYP1A1 mRNA by approximately 20-fold after 16 and 24 h. The transactivation was due to the activation of a region located at -1137 to +59 bp from CYP1A1, in particular, four xenobiotic responsive elements (XREs) existing in the region. AHR and the Ah receptor nuclear translocator interacted with XRE sequences in a gel shift assay using nuclear extract from Sudan III--treated HepG2 cells. Moreover, we suggest that constitutive androstane receptor could modify CYP1A1 transactivation by Sudan III. Copyright © 2012 Wiley Periodicals, Inc.

Crystal structure analysis of a bacterial aryl acylamidase belonging to the amidase signature enzyme family

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

Lee, Saeyoung; Park, Eun-Hye; Ko, Hyeok-Jin

2015-11-13

The atomic structure of a bacterial aryl acylamidase (EC 3.5.1.13; AAA) is reported and structural features are investigated to better understand the catalytic profile of this enzyme. Structures of AAA were determined in its native form and in complex with the analgesic acetanilide, p-acetaminophenol, at 1.70 Å and 1.73 Å resolutions, respectively. The overall structural fold of AAA was identified as an α/β fold class, exhibiting an open twisted β-sheet core surrounded by α-helices. The asymmetric unit contains one AAA molecule and the monomeric form is functionally active. The core structure enclosing the signature sequence region, including the canonical Ser-cisSer-Lys catalytic triad,more » is conserved in all members of the Amidase Signature enzyme family. The structure of AAA in a complex with its ligand reveals a unique organization in the substrate-binding pocket. The binding pocket consists of two loops (loop1 and loop2) in the amidase signature sequence and one helix (α10) in the non-amidase signature sequence. We identified two residues (Tyr{sup 136} and Thr{sup 330}) that interact with the ligand via water molecules, and a hydrogen-bonding network that explains the catalytic affinity over various aryl acyl compounds. The optimum activity of AAA at pH > 10 suggests that the reaction mechanism employs Lys{sup 84} as the catalytic base to polarize the Ser{sup 187} nucleophile in the catalytic triad. - Highlights: • We determined the first structure of a bacterial aryl acylamidase (EC 3.5.1.13). • Structure revealed spatially distinct architecture of the substrate-binding pocket. • Hydrogen-bonding with Tyr{sup 136} and Thr{sup 330} mediates ligand-binding and substrate.« less

Dual Visible Light Photoredox and Gold-Catalyzed Arylative Ring Expansion

PubMed Central

2015-01-01

A combination of visible light photocatalysis and gold catalysis is applied to a ring expansion–oxidative arylation reaction. The reaction provides an entry into functionalized cyclic ketones from the coupling reaction of alkenyl and allenyl cycloalkanols with aryl diazonium salts. A mechanism involving generation of an electrophilic gold(III)–aryl intermediate is proposed on the basis of mechanistic studies, including time-resolved FT-IR spectroscopy. PMID:24730447

An Efficient Process for Pd-Catalyzed C–N Cross-Coupling Reactions of Aryl Iodides: Insight Into Controlling Factors

PubMed Central

Fors, Brett P.; Davis, Nicole R.; Buchwald, Stephen L.

2009-01-01

An investigation into Pd-catalyzed C–N cross-coupling reactions of aryl iodides is described. NaI is shown to have a significant inhibitory effect on these processes. By switching to a solvent system in which the iodide byproduct was insoluble, reactions of aryl iodides were accomplished with the same efficiencies as aryl chlorides and bromides. Using catalyst systems based on certain biarylphosphine ligands, aryl iodides were successfully reacted with an array of primary and secondary amines in high yields. Lastly, reactions of heteroarylamines and heteroaryliodides were also conducted in high yields. PMID:19348431

Replacing Conventional Carbon Nucleophiles with Electrophiles: Nickel-Catalyzed Reductive Alkylation of Aryl Bromides and Chlorides

PubMed Central

2012-01-01

A general method is presented for the synthesis of alkylated arenes by the chemoselective combination of two electrophilic carbons. Under the optimized conditions, a variety of aryl and vinyl bromides are reductively coupled with alkyl bromides in high yields. Under similar conditions, activated aryl chlorides can also be coupled with bromoalkanes. The protocols are highly functional-group tolerant (−OH, −NHTs, −OAc, −OTs, −OTf, −COMe, −NHBoc, −NHCbz, −CN, −SO2Me), and the reactions are assembled on the benchtop with no special precautions to exclude air or moisture. The reaction displays different chemoselectivity than conventional cross-coupling reactions, such as the Suzuki–Miyaura, Stille, and Hiyama–Denmark reactions. Substrates bearing both an electrophilic and nucleophilic carbon result in selective coupling at the electrophilic carbon (R–X) and no reaction at the nucleophilic carbon (R–[M]) for organoboron (−Bpin), organotin (−SnMe3), and organosilicon (−SiMe2OH) containing organic halides (X–R–[M]). A Hammett study showed a linear correlation of σ and σ(−) parameters with the relative rate of reaction of substituted aryl bromides with bromoalkanes. The small ρ values for these correlations (1.2–1.7) indicate that oxidative addition of the bromoarene is not the turnover-frequency determining step. The rate of reaction has a positive dependence on the concentration of alkyl bromide and catalyst, no dependence upon the amount of zinc (reducing agent), and an inverse dependence upon aryl halide concentration. These results and studies with an organic reductant (TDAE) argue against the intermediacy of organozinc reagents. PMID:22463689

Novosphingobium aromaticivorans uses a Nu-class glutathione S-transferase as a glutathione lyase in breaking the β-aryl ether bond of lignin

PubMed Central

Kontur, Wayne S.; Bingman, Craig A.; Olmsted, Charles N.; Wassarman, Douglas R.; Ulbrich, Arne; Gall, Daniel L.; Smith, Robert W.; Yusko, Larissa M.; Fox, Brian G.; Noguera, Daniel R.; Coon, Joshua J.; Donohue, Timothy J.

2018-01-01

As a major component of plant cell walls, lignin is a potential renewable source of valuable chemicals. Several sphingomonad bacteria have been identified that can break the β-aryl ether bond connecting most phenylpropanoid units of the lignin heteropolymer. Here, we tested three sphingomonads predicted to be capable of breaking the β-aryl ether bond of the dimeric aromatic compound guaiacylglycerol-β-guaiacyl ether (GGE) and found that Novosphingobium aromaticivorans metabolizes GGE at one of the fastest rates thus far reported. After the ether bond of racemic GGE is broken by replacement with a thioether bond involving glutathione, the glutathione moiety must be removed from the resulting two stereoisomers of the phenylpropanoid conjugate β-glutathionyl-γ-hydroxypropiovanillone (GS-HPV). We found that the Nu-class glutathione S-transferase NaGSTNu is the only enzyme needed to remove glutathione from both (R)- and (S)-GS-HPV in N. aromaticivorans. We solved the crystal structure of NaGSTNu and used molecular modeling to propose a mechanism for the glutathione lyase (deglutathionylation) reaction in which an enzyme-stabilized glutathione thiolate attacks the thioether bond of GS-HPV, and the reaction proceeds through an enzyme-stabilized enolate intermediate. Three residues implicated in the proposed mechanism (Thr51, Tyr166, and Tyr224) were found to be critical for the lyase reaction. We also found that Nu-class GSTs from Sphingobium sp. SYK-6 (which can also break the β-aryl ether bond) and Escherichia coli (which cannot break the β-aryl ether bond) can also cleave (R)- and (S)-GS-HPV, suggesting that glutathione lyase activity may be common throughout this widespread but largely uncharacterized class of glutathione S-transferases. PMID:29449375

Identification of chemical modulators of the constitutive activated receptor (CAR) in a gene expression compendium

PubMed Central

Oshida, Keiyu; Vasani, Naresh; Jones, Carlton; Moore, Tanya; Hester, Susan; Nesnow, Stephen; Auerbach, Scott; Geter, David R.; Aleksunes, Lauren M.; Thomas, Russell S.; Applegate, Dawn; Klaassen, Curtis D.; Corton, J. Christopher

2015-01-01

The nuclear receptor family member constitutive activated receptor (CAR) is activated by structurally diverse drugs and environmentally-relevant chemicals leading to transcriptional regulation of genes involved in xenobiotic metabolism and transport. Chronic activation of CAR increases liver cancer incidence in rodents, whereas suppression of CAR can lead to steatosis and insulin insensitivity. Here, analytical methods were developed to screen for chemical treatments in a gene expression compendium that lead to alteration of CAR activity. A gene expression biomarker signature of 83 CAR-dependent genes was identified using microarray profiles from the livers of wild-type and CAR-null mice after exposure to three structurally-diverse CAR activators (CITCO, phenobarbital, TCPOBOP). A rank-based algorithm (Running Fisher’s algorithm (p-value ≤ 10-4)) was used to evaluate the similarity between the CAR biomarker signature and a test set of 28 and 32 comparisons positive or negative, respectively, for CAR activation; the test resulted in a balanced accuracy of 97%. The biomarker signature was used to identify chemicals that activate or suppress CAR in an annotated mouse liver/primary hepatocyte gene expression database of ~1850 comparisons. CAR was activated by 1) activators of the aryl hydrocarbon receptor (AhR) in wild-type but not AhR-null mice, 2) pregnane X receptor (PXR) activators in wild-type and to lesser extents in PXR-null mice, and 3) activators of PPARα in wild-type and PPARα-null mice. CAR was consistently activated by five conazole fungicides and four perfluorinated compounds. Comparison of effects in wild-type and CAR-null mice showed that the fungicide propiconazole increased liver weight and hepatocyte proliferation in a CAR-dependent manner, whereas the perfluorinated compound perfluorooctanoic acid (PFOA) increased these endpoints in a CAR-independent manner. A number of compounds suppressed CAR coincident with increases in markers of inflammation including acetaminophen, concanavalin A, lipopolysaccharide, and 300 nm silica particles. In conclusion, we have shown that a CAR biomarker signature coupled with a rank-based similarity method accurately predicts CAR activation. This analytical approach, when applied to a gene expression compendium, increased the universe of known chemicals that directly or indirectly activate CAR, highlighting the promiscuous nature of CAR activation and signaling through activation of other xenobiotic-activated receptors. PMID:25949234

The Aryl Hydrocarbon Receptor Meets Immunology: Friend or Foe? A Little of Both

PubMed Central

Julliard, Walker; Fechner, John H.; Mezrich, Joshua D.

2014-01-01

The aryl hydrocarbon receptor (AHR) has long been studied by toxicologists as a ligand-activated transcription factor that is activated by dioxin and other environmental pollutants such as polycyclic aromatic hydrocarbons (PAHs). The hallmark of AHR activation is the upregulation of the cytochrome P450 enzymes that metabolize many of these toxic compounds. However, recent findings demonstrate that both exogenous and endogenous AHR ligands can alter innate and adaptive immune responses including effects on T-cell differentiation. Kynurenine, a tryptophan breakdown product, is one such endogenous ligand of the AHR. Expression of indoleamine 2,3-dioxygenase by dendritic cells causes accumulation of kynurenine and results in subsequent tolerogenic effects including increased regulatory T-cell activity. At the same time, PAHs found in pollution enhance Th17 differentiation in the lungs of exposed mice via the AHR. In this perspective, we will discuss the importance of the AHR in the immune system and the role this might play in normal physiology and response to disease. PMID:25324842

Allergic responses and aryl hydrocarbon receptor novel pathway of mast cell activation.

PubMed

Sibilano, Riccardo; Pucillo, Carlo E; Gri, Giorgia

2015-01-01

The activation of the transcription factor aryl hydrocarbon receptor (AhR) is modulated by a wide variety of xenobiotics and ligands deriving from products of metabolism. The study of the contribution of AhR to allergic diseases has gained much interest in recent years. Here we discuss the role that environmental factors and metabolic products, particularly acting on AhR-expressing mast cells (MCs), could have in the development of local allergic/atopic response. Thus, this review will cover: a brief overview of the AhR mechanism of action in the immune system; a description of different AhR ligands and their effects to IgE-mediated MC activation in the allergic response, with particular attention to the role of IL-17; a discussion about the potential involvement of AhR in immune tolerance; and a conclusion on human diseases in which direct AhR activation of MC might have a major impact. Copyright © 2014 Elsevier Ltd. All rights reserved.

Discovery of potent cytotoxic ortho-aryl chalcones as new scaffold targeting tubulin and mitosis with affinity-based fluorescence.

PubMed

Zhu, Cuige; Zuo, Yinglin; Wang, Ruimin; Liang, Baoxia; Yue, Xin; Wen, Gesi; Shang, Nana; Huang, Lei; Chen, Yu; Du, Jun; Bu, Xianzhang

2014-08-14

A series of new ortho-aryl chalcones have been designed and synthesized. Many of these compounds were found to exhibit significant antiproliferation activity toward a panel of cancer cell lines. Selected compounds show potent cytotoxicity against several drug resistant cell lines including paclitaxel (Taxol) resistant human ovarian carcinoma cells, vincristine resistant human ileocecum carcinoma cells, and doxorubicin resistant human breast carcinoma cells. Further investigation revealed that active analogues could inhibit the microtubule polymerization by binding to colchicine site and thus induce multipolar mitosis, G2/M phase arrest, and apoptosis of cancer cells. Furthermore, affinity-based fluorescence enhancement was observed during the binding of active compounds with tubulin, which greatly facilitated the determination of tubulin binding site of the compounds. Finally, selected compound 26 was found to exhibit obvious in vivo antitumor activity in A549 tumor xenografts model. Our systematic studies implied a new scaffold targeting tubulin and mitosis for novel antitumor drug discovery.

Activities of five enzymes following soil disturbance and weed control in a Missouri forest

Treesearch

Felix, Jr. Ponder; Frieda Eivazi

2008-01-01

Forest disturbances associated with harvesting activities can affect soil properties including enzyme activity and overall soil quality. The activities of five enzymes (acid and alkaline phosphatases, betaglucosidase, aryl-sulfatase, and beta-glucosominidase) were measured after 8 years in soil from clearcut and uncut control plots of a Missouri oak-hickory (...

Active sites of the cytochrome p450cam (CYP101) F87W and F87A mutants. Evidence for significant structural reorganization without alteration of catalytic regiospecificity.

PubMed

Tuck, S F; Graham-Lorence, S; Peterson, J A; Ortiz de Montellano, P R

1993-01-05

Ferricyanide oxidation of the aryl-iron complexes formed by the reaction of cytochrome P450 enzymes with arylhydrazines causes in situ migration of the aryl group from the iron to the porphyrin nitrogen atoms. The regiochemistry of this migration, defined by the ratio of the four possible N-arylprotoporphyrin IX isomers, provides a method for mapping the topologies of cytochrome P450 active sites. The method has been validated by using it to examine the active site of cytochrome P450cam (CYP101), for which a crystal structure is available. In agreement with the crystal structure, reaction with phenylhydrazine gives a 5:25:70 ratio of the NA:NC:ND (subscript indicates pyrrole ring) N-phenylprotoporphyrin IX isomers. Naphthylhydrazine, however, yields exclusively the NC regioisomer and 4-(phenyl)phenylhydrazine the NA:NC:ND isomers in a 14:40:46 ratio. These isomer ratio differences are readily explained by topological differences between the upper and lower reaches of the active site. Having validated the aryl-iron shift as a topological probe, we used it to investigate the structural changes caused by mutation of Phe-87, a residue that provides the ceiling over pyrrole ring D in the crystal structure of cytochrome P450cam. Mutation of Phe-87 to a tryptophan causes no detectable change in the regiochemistry of camphor hydroxylation and only minor changes in the N-aryl isomer ratios. However, mutation of Phe-87 to an alanine, which was expected to open up the region above pyrrole ring D, severely decreased the proportion of the ND in favor of the NA isomer. Less rather than more space is therefore available over pyrrole ring D in the F87A mutant despite the fact that the regiochemistry of camphor hydroxylation remains unchanged. These results provide evidence for significant structural reorganization in the upper regions of the substrate binding site without alteration of the camphor hydroxylation regiospecificity in the F87A mutant.

Impact of aryloxy initiators on the living and immortal polymerization of lactide.

PubMed

Chile, L-E; Ebrahimi, T; Wong, A; Aluthge, D C; Hatzikiriakos, S G; Mehrkhodavandi, P

2017-05-23

This report describes two different methodologies for the synthesis of aryl end-functionalized poly(lactide)s (PLAs) catalyzed by indium complexes. In the first method, a series of para-functionalized phenoxy-bridged dinuclear indium complexes [(NNO)InCl] 2 (μ-Cl)(μ-OPh R ) (R = OMe (1), Me (2), H (3), Br (4), NO 2 (5)) were synthesized and fully characterized. The solution and solid state structures of these complexes reflect the electronic differences between these initiators. The polymerization rates correlate with the electron donating ability of the phenoxy initiators: the para-nitro substituted complex 5 is essentially inactive. However, the para-methoxy variant, while less active than the ethoxy-bridged complex [(NNO)InCl] 2 (μ-Cl)(μ-OEt) (A), shows sufficient activity. Alternatively, aryl-capped PLAs were synthesized via immortal polymerization of PLA with A in the presence of a range of arylated chain transfer agents. Certain aromatic diols shut down polymerization by chelating one indium centre to form a stable metal complex. Immortal ROP was successful when using phenol, and 1,5-naphthalenediol. These polymers were analysed and chain end fidelity was confirmed using 1 H NMR spectroscopy, MALDI-TOF mass spectrometry, and UV-Vis spectroscopy. This study shed light on possible speciation when attempting to generate PLA-lignin copolymers.

Chemical Probes for the Functionalization of Polyketide Intermediates**

PubMed Central

Riva, Elena; Wilkening, Ina; Gazzola, Silvia; Li, W M Ariel; Smith, Luke; Leadlay, Peter F; Tosin, Manuela

2014-01-01

A library of functionalized chemical probes capable of reacting with ketosynthase-bound biosynthetic intermediates was prepared and utilized to explore in vivo polyketide diversification. Fermentation of ACP mutants of S. lasaliensis in the presence of the probes generated a range of unnatural polyketide derivatives, including novel putative lasalocid A derivatives characterized by variable aryl ketone moieties and linear polyketide chains (bearing alkyne/azide handles and fluorine) flanking the polyether scaffold. By providing direct information on microorganism tolerance and enzyme processing of unnatural malonyl-ACP analogues, as well as on the amenability of unnatural polyketides to further structural modifications, the chemical probes constitute invaluable tools for the development of novel mutasynthesis and synthetic biology. PMID:25212788

Enantioselective construction of C-chiral allylic sulfilimines via the iridium-catalyzed allylic amination with S,S-diphenylsulfilimine: asymmetric synthesis of primary allylic amines† †Electronic supplementary information (ESI) available. See DOI: 10.1039/c4sc01317d Click here for additional data file.

PubMed Central

Grange, Rebecca L.; Clizbe, Elizabeth A.; Counsell, Emma J.

2015-01-01

We have devised a highly regio- and enantioselective iridium-catalyzed allylic amination reaction with the sulfur-stabilized aza-ylide, S,S-diphenylsulfilimine. This process provides a robust and scalable method for the construction of aryl-, alkyl- and alkenyl-substituted C-chiral allylic sulfilimines, which are important functional groups for organic synthesis. Additionally, the combination of the allylic amination with an in situ deprotection of the sulfilimine constitutes a convenient one-pot protocol for the construction of chiral nonracemic primary allylic amines. PMID:28936319

Developmental exposure to 2,3,7,8 tetrachlorodibenzo-p-dioxin attenuates later-life Notch1-mediated T cell development and leukemogenesis

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

Ahrenhoerster, Lori S.; Leuthner, Tess C.; Tate, Everett R.

2015-03-01

Over half of T cell acute lymphoblastic leukemia (T-ALL) patients have activating mutations in the Notch gene. Moreover, the contaminant 2,3,7,8 tetrachlorodibenzo-p-dioxin (TCDD) is a known carcinogen that mediates its toxicity through the aryl hydrocarbon receptor (AHR), and crosstalk between activated AHR and Notch signaling pathways has previously been observed. Given the importance of Notch signaling in thymocyte development and T-ALL disease progression, we hypothesized that the activated AHR potentiates disease initiation and progression in an in vivo model of Notch1-induced thymoma. This hypothesis was tested utilizing adult and developmental exposure paradigms to TCDD in mice expressing a constitutively activemore » Notch1 transgene (Notch{sup ICN-TG}). Following exposure of adult Notch{sup ICN-TG} mice to a single high dose of TCDD, we observed a significant increase in the efficiency of CD8 thymocyte generation. We next exposed pregnant mice to 3 μg/kg of TCDD throughout gestation and lactation to elucidate effects of developmental AHR activation on later-life T cell development and T-ALL-like thymoma susceptibility induced by Notch1. We found that the vehicle-exposed Notch{sup ICN-TG} offspring have a peripheral T cell pool heavily biased toward the CD4 lineage, while TCDD-exposed Notch{sup ICN-TG} offspring were biased toward the CD8 lineage. Furthermore, while the vehicle-exposed NotchICN-TG mice showed increased splenomegaly and B to T cell ratios indicative of disease, mice developmentally exposed to TCDD were largely protected from disease. These studies support a model where developmental AHR activation attenuates later-life Notch1-dependent impacts on thymocyte development and disease progression. - Highlights: • Adult mice exposed to 30 μg/kg TCDD have higher efficiency of CD8 thymocyte generation. • Mice carrying a constitutively active Notch transgene were exposed to 3 μg/kg TCDD throughout development. • Progression of Notch-induced thymoma was different in offspring exposed to TCDD developmentally. • Developmental AHR activation attenuates later-life Notch1-dependent impacts on T cell differentiation.« less

Synthesis of Secondary Aromatic Amides via Pd-Catalyzed Aminocarbonylation of Aryl Halides Using Carbamoylsilane as an Amide Source.

PubMed

Tong, Wenting; Cao, Pei; Liu, Yanhong; Chen, Jianxin

2017-11-03

Using N-methoxymethyl-N-organylcarbamoyl(trimethyl)silanes as secondary amides source, the direct transformation of aryl halides into the corresponding secondary aromatic amides via palladium-catalyzed aminocarbonylation is described. The reactions tolerated a broad range of functional groups on the aryl ring except big steric hindrance of substituent. The types and the relative position of substituents on the aryl ring impact the coupling efficiency.

Trace derivatives of kynurenine potently activate the aryl hydrocarbon receptor (AHR).

PubMed

Seok, Seung-Hyeon; Ma, Zhi-Xiong; Feltenberger, John B; Chen, Hongbo; Chen, Hui; Scarlett, Cameron; Lin, Ziqing; Satyshur, Kenneth A; Cortopassi, Marissa; Jefcoate, Colin R; Ge, Ying; Tang, Weiping; Bradfield, Christopher A; Xing, Yongna

2018-02-09

Cellular metabolites act as important signaling cues, but are subject to complex unknown chemistry. Kynurenine is a tryptophan metabolite that plays a crucial role in cancer and the immune system. Despite its atypical, non-ligand-like, highly polar structure, kynurenine activates the aryl hydrocarbon receptor (AHR), a PER, ARNT, SIM (PAS) family transcription factor that responds to diverse environmental and cellular ligands. The activity of kynurenine is increased 100-1000-fold by incubation or long-term storage and relies on the hydrophobic ligand-binding pocket of AHR, with identical structural signatures for AHR induction before and after activation. We purified trace-active derivatives of kynurenine and identified two novel, closely related condensation products, named trace-extended aromatic condensation products (TEACOPs), which are active at low picomolar levels. The synthesized compound for one of the predicted structures matched the purified compound in both chemical structure and AHR pharmacology. Our study provides evidence that kynurenine acts as an AHR pro-ligand, which requires novel chemical conversions to act as a receptor agonist. © 2018 by The American Society for Biochemistry and Molecular Biology, Inc.

Presidential Green Chemistry Challenge: 2008 Academic Award

EPA Pesticide Factsheets

Presidential Green Chemistry Challenge 2008 award winners, Professors Robert E. Maleczka, Jr. and Milton R. Smith, III, developed halogen-free, catalytic C-H activation/borylation to make aryl and heteroaryl boronic esters.

Synthesis of sulfadiazinyl acyl/aryl thiourea derivatives as calf intestinal alkaline phosphatase inhibitors, pharmacokinetic properties, lead optimization, Lineweaver-Burk plot evaluation and binding analysis.

PubMed

Sajid-Ur-Rehman; Saeed, Aamer; Saddique, Gufran; Ali Channar, Pervaiz; Ali Larik, Fayaz; Abbas, Qamar; Hassan, Mubashir; Raza, Hussain; Fattah, Tanzeela Abdul; Seo, Sung-Yum

2018-06-02

To seek the new medicinal potential of sulfadiazine drug, the free amino group of sulfadiazine was exploited to obtain acyl/aryl thioureas using simple and straightforward protocol. Acyl/aryl thioureas are well recognized bioactive pharmacophore containing moieties. A new series (4a-4j) of sulfadiazine derived acyl/aryl thioureas was synthesized and characterized through spectroscopic and elemental analysis. The synthesized derivatives 4a-4j were subjected to calf intestinal alkaline phosphatase (CIAP) activity. The derivative 4a-4j showed better inhibition potential compared to standard monopotassium phosphate (MKP). The compound 4c exhibited higher potential in the series with IC 50 0.251 ± 0.012 µM (standard KH 2 PO 4 4.317 ± 0.201 µM). Lineweaver-Burk plots revealed that most potent derivative 4c inhibition CIAP via mixed type pathway. Pharmacological investigations showed that synthesized compounds 4a-4j obey Lipinsk's rule. ADMET parameters evaluation predicted that these molecule show significant lead like properties with minimum possible toxicity and can serve as templates in drug designing. The synthetic compounds show none mutagenic and irritant behavior. Molecular docking analysis showed that compound 4c interacts with Asp273, His317 and Arg166 amino acid residues. Copyright © 2018. Published by Elsevier Ltd.

Substituted N-aryl-6-pyrimidinones: A new class of potent, selective, and orally active p38 MAP kinase inhibitors

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

Devadas, Balekudru; Selness, Shaun R.; Xing, Li

2012-02-28

A novel series of highly potent and selective p38 MAP kinase inhibitors was developed originating from a substituted N-aryl-6-pyrimidinone scaffold. SAR studies coupled with in vivo evaluations in rat arthritis model culminated in the identification of 10 with excellent oral efficacy. Compound 10 exhibited a significantly enhanced dissolution rate compared to 1, translating to a high oral bioavailability (>90%) in rat. In animal studies 10 inhibited LPS-stimulated production of tumor necrosis factor-{alpha} in a dose-dependent manner and demonstrated robust efficacy comparable to dexamethasone in a rat streptococcal cell wall-induced arthritis model.

Resting State and Elementary Steps of the Coupling of Aryl Halides with Thiols Catalyzed by Alkylbisphosphine Complexes of Palladium

PubMed Central

Alvaro, Elsa

2010-01-01

Detailed mechanistic studies on the coupling of aryl halides with thiols catalyzed by palladium complexes of the alkylbisphosphine ligand CyPF-tBu (1-dicyclohexylphosphino-2-di-tert-butylphosphinoethylferrocene) are reported. The elementary steps that constitute the catalytic cycle, i.e. oxidative addition, transmetalation and reductive elimination, have been studied, and their relative rates are reported. Each of the steps of the catalytic process occurs at temperatures that are much lower than those required for the reactions catalyzed by a combination of palladium precursors and CyPF-tBu. To explain these differences in rates between the catalytic and stoichiometric reactions, studies were conducted to identify the resting state of the catalyst of the reactions catalyzed by a combination of Pd(OAc)2 and CyPF-tBu, a combination of Pd(dba)2 and CyPF-tBu, or the likely intermediate Pd(CyPF-tBu)(Ar)(Br). These show that the major palladium complex in each case lies off of the catalytic cycle. The resting state of the reactions catalyzed by Pd(OAc)2 and CyPF-tBu was the palladium bis-thiolate complex [Pd(CyPF-tBu)(SR)2] (R = alkyl or aryl). The resting state in reactions catalyzed by Pd2(dba)3 and CyPF-tBu was the binuclear complex [Pd(CyPF-tBu)]2(μ2, η2-dba) (9). The resting state of reactions of both aromatic and aliphatic thiols catalyzed by [Pd(CyPF-tBu)(p-tolyl)(Br)] (3a) was the hydridopalladium thiolate complex [Pd(CyPF-tBu)(H)(SR)] (R= alkyl and aryl). All these palladium species have been prepared independently, and the mechanisms by which they enter the catalytic cycle have been examined in detail. These features of the reaction catalyzed by palladium and CyPF-tBu have been compared with those of reactions catalyzed by the alkylbisphosphine DiPPF and Pd(OAc)2 or Pd(dba)2. Our data indicate that the resting states of these reactions are similar to each other and that our mechanistic conclusions about reactions catalyzed by palladium and CyPF-tBu can be extrapolated to reactions catalyzed by complexes of other electron-rich bisphosphines. PMID:19453106

Copper-catalyzed direct synthesis of diaryl 1,2-diketones from aryl iodides and propiolic acids.

PubMed

Min, Hongkeun; Palani, Thiruvengadam; Park, Kyungho; Hwang, Jinil; Lee, Sunwoo

2014-07-03

Benzil derivatives such as diaryl 1,2-diketones are synthesized via the direct decarboxylative coupling reaction of aryl propiolic acids and their oxidation. The optimized conditions are that the reaction of aryl propiolic acids and aryl iodides is conducted at 140 °C for 6 h in the presence of 10 mol % CuI/Cu(OTf)2 and Cs2CO3, after which HI (aq) is added and further reacted. The method shows good functional group tolerance toward ester, aldehyde, cyano, and nitro groups. In addition, symmetrical diaryl 1,2-diketones are obtained from aryl iodides and propiolic acid in the presence of palladium and copper catalysts.

Camphyl-based α-diimine palladium complexes: highly efficient precatalysts for direct arylation of thiazoles in open-air.

PubMed

Chen, Fu-Min; Lu, Dong-Dong; Hu, Li-Qun; Huang, Ju; Liu, Feng-Shou

2017-07-21

Based on the strategy of the development of phosphine-free palladium-catalyzed direct C-H arylation, a series of camphyl-based α-diimine palladium complexes bearing sterically bulky substituents were synthesized and characterized. The palladium complexes were applied for the cross-coupling of thiazole derivatives with aryl bromides. The effect of the sterically bulky substituent on the N-aryl moiety as well as the reaction conditions was screened. Under the optimal protocols, a wide range of aryl bromides can be smoothly coupled with thiazoles in good to excellent yields in the presence of a low palladium loading of 0.2 mol% under open-air conditions.

Copper(II)-catalyzed trifluoromethylation of N-aryl imines.

PubMed

Zhang, Yong-Qiang; Liu, Ji-Dan; Xu, Hao

2013-10-07

Methods for imine trifluoromethylation are of great importance because amines with trifluoromethylated stereogenic centers are useful building blocks for synthetic chemistry and drug discovery. Herein, we describe a new copper(II)-catalyzed imine trifluoromethylation method without the use of Lewis base activators, presumably through cooperative activation.

Indolyl aryl sulfones (IASs): development of highly potent NNRTIs active against wt-HIV-1 and clinically relevant drug resistant mutants.

PubMed

Silvestri, Romano; Artico, Marino

2005-01-01

Indolyl aryl sulfones (IASs) are a potent class of NNRTIs developed from L-737,126, a lead agent discovered by Merck AG. IAS derivatives are endowed with inhibitory activities against wt HIV-1 in the low nanomolar concentration range. Introduction of two methyl groups at positions 3 and 5 of the phenyl ring of the aryl sulfonyl moiety furnished IAS derivatives such as 5-chloro- or 5-bromo-3-[(3,5-dimethylphenyl)sulfonyl]indole-2-carboxyamide, which showed very potent and selective anti-HIV-1 activity against some mutants carrying NNRTI resistant mutations at positions 103 and 181 of the reverse transcriptase. IAS derivatives bearing 2-hydroxyethylcarboxyamide or 2-hydroxyethylcarboxyhydrazide groups at position 2 of the indole nucleus were more active than L-737,126 against the K103N-Y181C double mutant. A great improvement of antiviral activity against wt HIV-1 and resistant mutants was obtained by coupling 1-3 simple amino acids, such as glycine and alanine, in sequence, with the 3-[(3,5-dimethylphenyl)sulfonyl]-1H-indole-2-carbonyl moiety. The transformation of the chain terminus into amide or hydrazide, produced short peptides with high selectivity and potent activity against wt HIV-1, and the viral mutants Y181C, K103N-Y181C and EFV(R). IAS having two halogen atoms at the indole showed potent inhibitory activity against the Y181C and the EFV(R) resistant mutant strains. In particular, the introduction of a fluorine atom at position 4 of the indole ring notably contributed to improve the antiviral activities against both wt and the related resistant mutants. 5-Nitro-IASs were highly active against wt HIV-1 and exhibited low cytotoxicity. Experimental data highlighted the class IAS derivatives as promising candidates for clinical trials.

Controlling First-Row Catalysts: Amination of Aryl and Heteroaryl Chlorides and Bromides with Primary Aliphatic Amines Catalyzed by a BINAP-Ligated Single-Component Ni(0) Complex

PubMed Central

2015-01-01

First-row metal complexes often undergo undesirable one-electron redox processes during two-electron steps of catalytic cycles. We report the amination of aryl chlorides and bromides with primary aliphatic amines catalyzed by a well-defined, single-component nickel precursor (BINAP)Ni(η2-NC-Ph) (BINAP = 2,2′-bis(biphenylphosphino)-1,1′-binaphthalene) that minimizes the formation of Ni(I) species and (BINAP)2Ni. The scope of the reaction encompasses electronically varied aryl chlorides and nitrogen-containing heteroaryl chlorides, including pyridine, quinoline, and isoquinoline derivatives. Mechanistic studies support the catalytic cycle involving a Ni(0)/Ni(II) couple for this nickel-catalyzed amination and are inconsistent with a Ni(I) halide intermediate. Monitoring the reaction mixture by 31P NMR spectroscopy identified (BINAP)Ni(η2-NC-Ph) as the resting state of the catalyst in the amination of both aryl chlorides and bromides. Kinetic studies showed that the amination of aryl chlorides and bromides is first order in both catalyst and aryl halide and zero order in base and amine. The reaction of a representative aryl chloride is inverse first order in PhCN, but the reaction of a representative aryl bromide is zero order in PhCN. This difference in the order of the reaction in PhCN indicates that the aryl chloride reacts with (BINAP)Ni(0), formed by dissociation PhCN from (BINAP)Ni(η2-NC-Ph), but the aryl bromide directly reacts with (BINAP)Ni(η2-NC-Ph). The overall kinetic behavior is consistent with turnover-limiting oxidative addition of the aryl halide to Ni(0). Several pathways for catalyst decomposition were identified, such as the formation of the catalytically inactive bis(amine)-ligated arylnickel(II) chloride, (BINAP)2Ni(0), and the Ni(I) species [(BINAP)Ni(μ-Cl)]2. By using a well-defined nickel complex as catalyst, the formation of (BINAP)2Ni(0) is avoided and the formation of the Ni(I) species [(BINAP)Ni(μ-Cl)]2 is minimized. PMID:24397570

Different regulation of aryl hydrocarbon receptor-regulated genes in response to dioxin in undifferentiated and neuronally differentiated human neuroblastoma SH-SY5Y cells.

PubMed

Imran, Saima; Ferretti, Patrizia; Vrzal, Radim

2015-01-01

Some environmental pollutants derived from industrial processes have been suggested to be responsible for neurological impairment in children, especially in heavily polluted areas. Since these compounds are usually activators of aryl hydrocarbon receptor (AhR), it would be important to better understand the molecular pathways downstream of AhR leading to neural deficits. To this purpose, appropriate in vitro human neural model is much needed. Here we have investigated whether undifferentiated and neuronally differentiated human neuroblastoma cells, SH-SY5Y cells, can provide a suitable model for monitoring AhR activity induced by environmental pollutants, focusing on 2,3,7,8-tetrachlordibenzo-p-dioxin (TCDD), a known activator of AhR. Further characterization of differentiated SH-SY5Y showed an increase in AhRR (aryl hydrocarbon receptor repressor), no change in ARNT1 (AhR nuclear translocator 1), and a decrease in ARNT2 expression with differentiation; in contrast, AhR was undetectable in both undifferentiated and differentiated cells. Nonetheless, treatment of parental as well as differentiated SH-SY5Y cells with TCDD resulted in the induction of AhR-regulated genes, CYP1A1 and CYP1B1; AhRR expression was also affected, but to a much smaller extent. These results indicate that undifferentiated SH-SY5Y are less sensitive to TCDD than neuronally differentiated ones, suggesting a higher resistance of the undifferentiated tumor cells to toxic insults. They also suggest that TCDD in these cells may not act via direct activation of AhR that is undetectable in SH-SY5Y as well as in differentiated neurons. Hence, these cells do not provide an appropriate model for studying ligand-mediated activation of AhR.

Selective Hydrogen Atom Abstraction through Induced Bond Polarization: Direct α-Arylation of Alcohols through Photoredox, HAT, and Nickel Catalysis.

PubMed

Twilton, Jack; Christensen, Melodie; DiRocco, Daniel A; Ruck, Rebecca T; Davies, Ian W; MacMillan, David W C

2018-05-04

The combination of nickel metallaphotoredox catalysis, hydrogen atom transfer catalysis, and a Lewis acid activation mode, has led to the development of an arylation method for the selective functionalization of alcohol α-hydroxy C-H bonds. This approach employs zinc-mediated alcohol deprotonation to activate α-hydroxy C-H bonds while simultaneously suppressing C-O bond formation by inhibiting the formation of nickel alkoxide species. The use of Zn-based Lewis acids also deactivates other hydridic bonds such as α-amino and α-oxy C-H bonds. This approach facilitates rapid access to benzylic alcohols, an important motif in drug discovery. A 3-step synthesis of the drug Prozac exemplifies the utility of this new method. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Studies on the synthesis and biological activitiy of 6-ethyl-4-aryl-5-methoxycarbonyl-3,4-dihydropyrimidin-2(1H)-ones.

PubMed

Saraç, Selma; Ciftçi, Murat; Zorkun, Inci Selin; Tunç, Ozgül; Erol, Kevser

2007-01-01

6-Ethyl-4-aryl-5-methoxycarbonyl-3,4-dihydropyrimidin-2(1H)-one derivatives (1-10) were synthesized by condensing urea with methyl 3-oxopentanoate and aromatic aldehydes in absol. ethanol using HCl as a catalyst according to the Biginelli reaction. The structures of the compounds were confirmed by spectroscopic and elemental analysis. The calcium channel blocker activities of the compounds were determined by the tests performed on isolated rat ileum and lamb carotid artery. On the isolated rat ileum, compound 2 was found to be more effective at 10(-5) mol/L concentration than nicardipine (CAS 55985-32-5). On the lamb carotid artery compounds 5, 6 and 4, 5, 6 were significantly active at 10(-6) mol/L and 10(-5) mol/L concentrations, respectively.

Palladium coupling catalysts for pharmaceutical applications.

PubMed

Doucet, Henri; Hierso, Jean-Cyrille

2007-11-01

This review discusses recent advances made in the area of palladium-catalyzed coupling reactions and describes a selection of the catalytic systems that are useful in the preparation of valuable compounds for the pharmaceutical industry. Most of these types of syntheses have used either simple palladium salts or palladium precursors associated with electron-rich mono- or bidentate phosphine ligands as catalysts. For some reactions, ligands such as triphenyl phosphine, 1,1'-bis(diphenylphosphino)ferrocene, a carbene or a bipyridine have also been employed. Several new procedures for the Suzuki cross-coupling reaction, the activation of aryl chlorides, the functionalization of aromatics and the synthesis of heteroaromatics are discussed. The C-H activation/ functionalization reactions of aryl and heteroaryl derivatives have emerged as powerful tools for the preparation of biaryl compounds, and the recent procedures and catalysts employed in this promising field are also highlighted herein.

Effect of conformational mobility and hydrogen-bonding interactions on the selectivity of some guanidinoaryl-substituted mechanism-based inhibitors of trypsin-like serine proteases.

PubMed

Rai, R; Katzenellenbogen, J A

1992-11-13

Previously, we have reported that some guanidino-substituted alpha- and beta-aryl enol lactones I and II behaved as selective, mechanism-based inhibitors of some trypsin-like proteases (Rai, R.; Katzenellenbogen, J.A. J. Med. Chem., submitted). In this study, we describe the synthesis and kinetic evaluation of some related, guanidino-substituted enol lactones having greater conformational mobility and affording additional hydrogen-bonding sites at the active site. The alpha-aryl-substituted lactones 1 and 2, which have greater conformational mobility in the guanidinoaryl linkage than I, selectively inhibited the trypsin-like enzymes, and they were relatively poor inactivators of alpha-chymotrypsin and human neutrophil elastase (HNE). The iodo enol lactone 2 permanently inactivated trypsin, urokinase, tissue plasminogen activator, and plasmin, showing exceptionally high specificity in its interaction with trypsin and urokinase. The selectivity pattern exhibited by the closely related, conformationally less mobile alpha-aryl-substituted iodo lactone Ib, which was previously shown to be a selective suicide substrate of urokinase and plasmin, provides an interesting comparison. The alpha-benzamido-substituted lactones 3 and 4, which afford an additional site for active-site hydrogen bonding, were found to be very potent alternate substrate inhibitors of trypsin and urokinase. In addition, the iodo lactone 4 permanently inactivated alpha-chymotrypsin. The importance of secondary interactions in increasing the specificities in the case of alpha-chymotrypsin is discussed.

Comparative molecular field analysis and molecular docking studies on novel aryl chalcone derivatives against an important drug target cysteine protease in Plasmodium falciparum.

PubMed

Thillainayagam, Mahalakshmi; Anbarasu, Anand; Ramaiah, Sudha

2016-08-21

The computational studies namely molecular docking simulations and Comparative Molecular Field Analysis (CoMFA) are executed on series of 52 novel aryl chalcones derivatives using Plasmodium falciparum cysteine proteases (falcipain - 2) as vital target. In the present study, the correlation between different molecular field effects namely steric and electrostatic interactions and chemical structures to the inhibitory activities of novel aryl chalcone derivatives is inferred to perceive the major structural prerequisites for the rational design and development of potent and novel lead anti-malarial compound. The apparent binding conformations of all the compounds at the active site of falcipain - 2 and the hydrogen-bond interactions which could be used to modify the inhibitory activities are identified by using Surflex-dock study. Statistically significant CoMFA model has been developed with the cross-validated correlation coefficient (q(2)) of 0.912 and the non-cross-validated correlation coefficient (r(2)) of 0.901. Standard error of estimation (SEE) of 0.210, with the optimum number of components is ten. The predictability of the derived model is examined with a test set consists of sixteen compounds and the predicted r(2) value is found to be 0.924. The docking and QSAR study results confer crucial suggestions for the optimization of novel 1,3-diphenyl-2-propen-1-one derivatives and synthesis of effective anti- malarial compounds. Copyright © 2016 Elsevier Ltd. All rights reserved.

Correlation of Hydrogen-Atom Abstraction Reaction Efficiencies for Aryl Radicals with their Vertical Electron Affinities and the Vertical Ionization Energies of the Hydrogen Atom Donors

PubMed Central

Jing, Linhong; Nash, John J.

2009-01-01

The factors that control the reactivities of aryl radicals toward hydrogen-atom donors were studied by using a dual-cell Fourier-transform ion cyclotron resonance mass spectrometer (FT – ICR). Hydrogen-atom abstraction reaction efficiencies for two substrates, cyclohexane and isopropanol, were measured for twenty-three structurally different, positively-charged aryl radicals, which included dehydrobenzenes, dehydronaphthalenes, dehydropyridines, and dehydro(iso)quinolines. A logarithmic correlation was found between the hydrogen-atom abstraction reaction efficiencies and the (calculated) vertical electron affinities (EA) of the aryl radicals. Transition state energies calculated for three of the aryl radicals with isopropanol were found to correlate linearly with their (calculated) EAs. No correlation was found between the hydrogen-atom abstraction reaction efficiencies and the (calculated) enthalpy changes for the reactions. Measurement of the reaction efficiencies for the reactions of several different hydrogen-atom donors with a few selected aryl radicals revealed a logarithmic correlation between the hydrogen-atom abstraction reaction efficiencies and the vertical ionization energies (IE) of the hydrogen-atom donors, but not the lowest homolytic X – H (X = heavy atom) bond dissociation energies of the hydrogen-atom donors. Examination of the hydrogen-atom abstraction reactions of twenty-nine different aryl radicals and eighteen different hydrogen-atom donors showed that the reaction efficiency increases (logarithmically) as the difference between the IE of the hydrogen-atom donor and the EA of the aryl radical decreases. This dependence is likely to result from the increasing polarization, and concomitant stabilization, of the transition state as the energy difference between the neutral and ionic reactants decreases. Thus, the hydrogen-atom abstraction reaction efficiency for an aryl radical can be “tuned” by structural changes that influence either the vertical EA of the aryl radical or the vertical IE of the hydrogen atom donor. PMID:19061320

Structural hierarchy controlling dimerization and target DNA recognition in the AHR transcriptional complex.

PubMed

Seok, Seung-Hyeon; Lee, Woojong; Jiang, Li; Molugu, Kaivalya; Zheng, Aiping; Li, Yitong; Park, Sanghyun; Bradfield, Christopher A; Xing, Yongna

2017-05-23

The aryl hydrocarbon receptor (AHR) belongs to the PAS (PER-ARNT-SIM) family transcription factors and mediates broad responses to numerous environmental pollutants and cellular metabolites, modulating diverse biological processes from adaptive metabolism, acute toxicity, to normal physiology of vascular and immune systems. The AHR forms a transcriptionally active heterodimer with ARNT (AHR nuclear translocator), which recognizes the dioxin response element (DRE) in the promoter of downstream genes. We determined the crystal structure of the mammalian AHR-ARNT heterodimer in complex with the DRE, in which ARNT curls around AHR into a highly intertwined asymmetric architecture, with extensive heterodimerization interfaces and AHR interdomain interactions. Specific recognition of the DRE is determined locally by the DNA-binding residues, which discriminates it from the closely related hypoxia response element (HRE), and is globally affected by the dimerization interfaces and interdomain interactions. Changes at the interdomain interactions caused either AHR constitutive nuclear localization or failure to translocate to nucleus, underlying an allosteric structural pathway for mediating ligand-induced exposure of nuclear localization signal. These observations, together with the global higher flexibility of the AHR PAS-A and its loosely packed structural elements, suggest a dynamic structural hierarchy for complex scenarios of AHR activation induced by its diverse ligands.

Structural hierarchy controlling dimerization and target DNA recognition in the AHR transcriptional complex

PubMed Central

Lee, Woojong; Jiang, Li; Molugu, Kaivalya; Zheng, Aiping; Li, Yitong; Park, Sanghyun; Bradfield, Christopher A.; Xing, Yongna

2017-01-01

The aryl hydrocarbon receptor (AHR) belongs to the PAS (PER-ARNT-SIM) family transcription factors and mediates broad responses to numerous environmental pollutants and cellular metabolites, modulating diverse biological processes from adaptive metabolism, acute toxicity, to normal physiology of vascular and immune systems. The AHR forms a transcriptionally active heterodimer with ARNT (AHR nuclear translocator), which recognizes the dioxin response element (DRE) in the promoter of downstream genes. We determined the crystal structure of the mammalian AHR–ARNT heterodimer in complex with the DRE, in which ARNT curls around AHR into a highly intertwined asymmetric architecture, with extensive heterodimerization interfaces and AHR interdomain interactions. Specific recognition of the DRE is determined locally by the DNA-binding residues, which discriminates it from the closely related hypoxia response element (HRE), and is globally affected by the dimerization interfaces and interdomain interactions. Changes at the interdomain interactions caused either AHR constitutive nuclear localization or failure to translocate to nucleus, underlying an allosteric structural pathway for mediating ligand-induced exposure of nuclear localization signal. These observations, together with the global higher flexibility of the AHR PAS-A and its loosely packed structural elements, suggest a dynamic structural hierarchy for complex scenarios of AHR activation induced by its diverse ligands. PMID:28396409

Structural hierarchy controlling dimerization and target DNA recognition in the AHR transcriptional complex

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

Seok, Seung-Hyeon; Lee, Woojong; Jiang, Li

he aryl hydrocarbon receptor (AHR) belongs to the PAS (PER-ARNT-SIM) family transcription factors and mediates broad responses to numerous environmental pollutants and cellular metabolites, modulating diverse biological processes from adaptive metabolism, acute toxicity, to normal physiology of vascular and immune systems. The AHR forms a transcriptionally active heterodimer with ARNT (AHR nuclear translocator), which recognizes the dioxin response element (DRE) in the promoter of downstream genes. We determined the crystal structure of the mammalian AHR–ARNT heterodimer in complex with the DRE, in which ARNT curls around AHR into a highly intertwined asymmetric architecture, with extensive heterodimerization interfaces and AHR interdomainmore » interactions. Specific recognition of the DRE is determined locally by the DNA-binding residues, which discriminates it from the closely related hypoxia response element (HRE), and is globally affected by the dimerization interfaces and interdomain interactions. Changes at the interdomain interactions caused either AHR constitutive nuclear localization or failure to translocate to nucleus, underlying an allosteric structural pathway for mediating ligand-induced exposure of nuclear localization signal. These observations, together with the global higher flexibility of the AHR PAS-A and its loosely packed structural elements, suggest a dynamic structural hierarchy for complex scenarios of AHR activation induced by its diverse ligands.« less

Catalytic coupling of sp2- and sp-hybridized carbon-hydrogen bonds with vinylmetalloid compounds.

PubMed

Marciniec, Bogdan

2007-10-01

In the Account given herein, it has been shown that silylative coupling of olefins, well-recognized as a new catalytic route for the activation of double bond C-H bond of olefins and double bond C-Si bond of vinylsilicon compounds with ethylene elimination, can be extended over both other vinylmetalloid derivatives (double bond C-E) (where E = Ge, B, and others) as well as the activation of triple bond C-H, double bond C aryl-H, and -O-H bond of alcohols and silanols. This general transformation is catalyzed by transition-metal complexes (mainly Ru and Rh) containing or initiating TM-H and/or TM-E bonds (inorganometallics). This new general catalytic route for the activation of double bond C-H and triple bond C-H as well as double bond C-E bonds called metallative coupling or trans-metalation (cross-coupling, ring-closing, and polycondensation) constitutes an efficient method (complementary to metathesis) for stereo- and regioselective synthesis of a variety of molecular and macromolecular compounds of vinyl-E (E = Si, B, and Ge) and ethynyl-E (E = Si and Ge) functionality, also potent organometallic reagents for efficient synthesis of highly pi-conjugated organic compounds. The mechanisms of the catalysis of this deethenative metalation have been supported by equimolar reactions of TM-H and/or TM-E with initial substances and reactions with deuterium-labeled reagents.

Synthesis of aryl azides and vinyl azides via proline-promoted CuI-catalyzed coupling reactions.

PubMed

Zhu, Wei; Ma, Dawei

2004-04-07

The coupling reaction of aryl halides or vinyl iodide with sodium azide under catalysis of CuI/L-proline works at relatively low temperature to provide aryl azides or vinyl azides in good to excellent yields.

Mechanism of the Reaction between Alkyl- and Aryl Grignard Reagents and Hexachlorocyclotriphosphazene: An Explanation of Bi(Cyclophosphazene Formation).

DTIC Science & Technology

1982-06-24

ADAI& "I PENNSYLVANIA STATE UNIV UNIVERSITY PARK DEPT OF CHEMISTRY F/S 7/3 ADA MECHANISM OF THE REACTION BETWEEN ALKYL - AND ARYL GRIGNARD REMG-ETC (U...TITLE (and Subliflo) S. TYPE OF REPORT A PERIOD COVERED MECHANISM OF THE REACTION BETWEEN ALKYL - AND ARYL GRIGNARD REAGENTS AND HEXACHLOROCYCLOTRIPHOS...Report No. 27 MECHANISM OF THE REACTION BETWEEN ALKYL - AND ARYL GRIGNARD REAGENTS AND HEXACHLOROCYCLOTRIPHOSPHAZENE: AN EXPLANATION OF BI(CYCLOPHOSPHAZENE

Palladium-catalysed carbonylative α-arylation of nitromethane.

PubMed

Lian, Zhong; Friis, Stig D; Skrydstrup, Troels

2015-02-28

A simple and mild Pd-catalysed carbonylative α-arylation of nitromethane has been realised providing access to α-nitro aryl ketones from an array of aryl and heteroaryl iodides. The methodology requires only a mild base and uses the convenient solid CO releasing molecule, COgen in a two-chamber system. Changing to the isotopically labelled (13)COgen, [(13)C]-acyl labelling can be effected through the generation of a near stoichiometric amount of (13)CO. Lastly, the significance of the generated products as synthetic intermediates is demonstrated.

OBO-Protected Pyruvates as Reagents for the Synthesis of Functionalized Heteroaromatic Compounds.

PubMed

Alves Esteves, C Henrique; Koyioni, Maria; Christensen, Kirsten E; Smith, Peter D; Donohoe, Timothy J

2018-06-15

Pd-catalyzed α-arylation of methyl-OBO-ketone (OBO = 4-methyl-2,6,7-trioxabicyclo[2.2.2]octan-1-yl) gives rise to arylated OBO-protected pyruvates. By appropriate prefunctionalization of the aryl ring or by subsequent functionalization at the α-carbonyl position of the arylated OBO-ketones, useful diketo OBO-protected carboxylates can be generated. Cyclization, aromatization, and OBO deprotection of these intermediates, using two distinct routes, gives access to valuable α-acyl heteroaromatic compounds.

Diastereoselective Synthesis of Symmetrical and Unsymmetrical Tetrahydropyridines Catalyzed by Bi(III) Immobilized on Triazine Dendrimer Stabilized Magnetic Nanoparticles.

PubMed

Asadi, Beheshteh; Landarani-Isfahani, Amir; Mohammadpoor-Baltork, Iraj; Tangestaninejad, Shahram; Moghadam, Majid; Mirkhani, Valiollah; Amiri Rudbari, Hadi

2017-06-12

Unsymmetrical 1,2,5,6-tetrahydropyridine-3-carboxylates were obtained for the first time from a five-component Fe 3 O 4 @TDSN-Bi(III)-catalyzed reaction of aryl aldehydes, aryl amines, and ethyl acetoacetate. This magnetically separable catalyst enabled the selective incorporation of two different aryl amines or two different aryl aldehydes into the product, and provided excellent yields, short reaction times, mild reaction conditions, satisfactory catalyst recyclability, and low catalyst loading.

Probing the role of the vancomycin e-ring aryl chloride: selective divergent synthesis and evaluation of alternatively substituted E-ring analogues.

PubMed

Pinchman, Joseph R; Boger, Dale L

2013-05-23

The selective functionalization of vancomycin aglycon derivatives through conversion of the E-ring aryl chloride to a reactive boronic acid and its use in the synthesis of a systematic series of vancomycin E-ring analogues are described. The series was used to examine the E-ring chloride impact in binding d-Ala-d-Ala and on antimicrobial activity. In contrast to the reduced activity of the unsubstituted E-ring derivatives, hydrophobic and relatively nonpolar substituents approach or match the chloro-substituted vancomycin and were insensitive to the electronic character of the substituent (e.g., Cl vs CN/OMe), whereas highly polar substituents fail to provide the enhancements. Moreover, the active permethylated vancomycin aglycon derivatives exhibit VanB VRE antimicrobial activity at levels that approach (typically within 2-fold) their activity against sensitive bacteria. The robust borylation reaction also enabled the functionalization of a minimally protected vancomycin aglycon (N-Boc-vancomycin aglycon) and provides a direct method for the preparation of previously inaccessible analogues.

Synthesis and structure-activity relationships of novel lincomycin derivatives part 3: discovery of the 4-(pyrimidin-5-yl)phenyl group in synthesis of 7(S)-thiolincomycin analogs.

PubMed

Wakiyama, Yoshinari; Kumura, Ko; Umemura, Eijiro; Masaki, Satomi; Ueda, Kazutaka; Sato, Yasuo; Watanabe, Takashi; Hirai, Yoko; Ajito, Keiichi

2017-01-01

Novel lincomycin derivatives possessing an aryl phenyl group or a heteroaryl phenyl group at the C-7 position via sulfur atom were synthesized by Pd-catalyzed cross-coupling reactions of 7(S)-7-deoxy-7-thiolincomycin (5) with various aryl halides. This reaction is the most useful method to synthesize a variety of 7(S)-7-deoxy-7-thiolincomycin derivatives. On the basis of analysis of structure-activity relationships of these novel lincomycin derivatives, we found that (a) the location of basicity in the C-7 side chain was an important factor to enhance antibacterial activities, and (b) compounds 22, 36, 42, 43 and 44 had potent antibacterial activities against a variety of Streptococcus pneumoniae with erm gene, which cause severe respiratory infections, even compared with our C-7-modified lincomycin analogs (1-4) reported previously. Furthermore, 7(S)-configuration was found to be necessary for enhancing antibacterial activities from comparison of configurations at the 7-position of 36 (S-configuration) and 41 (R-configuration).

Light-Induced C-H Arylation of (Hetero)arenes by In Situ Generated Diazo Anhydrides.

PubMed

Cantillo, David; Mateos, Carlos; Rincon, Juan A; de Frutos, Oscar; Kappe, C Oliver

2015-09-07

Diazo anhydrides (Ar-N=N-O-N=N-Ar) have been known since 1896 but have rarely been used in synthesis. This communication describes the development of a photochemical catalyst-free C-H arylation methodology for the preparation of bi(hetero)aryls by the one-pot reaction of anilines with tert-butyl nitrite and (hetero)arenes under neutral conditions. The key step in this procedure is the in situ formation and subsequent photochemical (>300 nm) homolytic cleavage of a transient diazo anhydride intermediate. The generated aryl radical then efficiently reacts with a (hetero)arene to form the desired bi(hetero)aryls producing only nitrogen, water, and tert-butanol as byproducts. The scope of the reaction for several substituted anilines and (hetero)arenes was investigated. A continuous-flow protocol increasing selectivity and safety has been developed enabling the experimentally straightforward preparation of a variety of substituted bi(hetero)aryls within 45 min of reaction time. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Dual nickel and Lewis acid catalysis for cross-electrophile coupling: the allylation of aryl halides with allylic alcohols† †Electronic supplementary information (ESI) available. CCDC 1515176. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c7sc03140h

PubMed Central

Jia, Xue-Gong; Guo, Peng; Duan, Jicheng

2017-01-01

Controlling the selectivity in cross-electrophile coupling reactions is a significant challenge, particularly when one electrophile is much more reactive. We report a general and practical strategy to address this problem in the reaction between reactive and unreactive electrophiles by a combination of nickel and Lewis acid catalysis. This strategy is used for the coupling of aryl halides with allylic alcohols to form linear allylarenes selectively. The reaction tolerates a wide range of functional groups (e.g. silanes, boronates, anilines, esters, alcohols, and various heterocycles) and works with various allylic alcohols. Complementary to most current routes for the C3 allylation of an unprotected indole, this method provides access to C2 and C4–C7 allylated indoles. Preliminary mechanistic experiments reveal that the reaction might start with an aryl nickel intermediate, which then reacts with Lewis acid activated allylic alcohols in the presence of Mn. PMID:29629130

Design and synthesis of novel stiripentol analogues as potential anticonvulsants.

PubMed

Aboul-Enein, Mohamed N; El-Azzouny, Aida A; Attia, Mohamed I; Maklad, Yousreya A; Amin, Kamilia M; Abdel-Rehim, Mohamed; El-Behairy, Mohammed F

2012-01-01

A series of stiripentol (STP) analogues namely, 2-[(1E)-1-(1,3-benzodioxol-5-yl)-4,4-dimethylpent-1-en-3-ylidene]-N-(aryl/H)hydrazinecarboxamides 7a-h, (±)-(5RS)-N-(aryl/H)-(1,3-benzodioxol-5-yl)-3-tert-butyl-4,5-dihydro-1H-pyrazole-1-carboxamides (±)-8a-h, and (±)-[(5RS)-(1,3-benzodioxol-5-yl)-3-tert-butyl-4,5-dihydro-1H-pyrazol-1-yl](aryl)methanones (±)-13a-f was synthesized by adopting appropriate synthetic routes and was pharmacologically evaluated in the preliminary anticonvulsant screens. The selected bioactive new chemical entities were subjected to ED(50) determination and neurotoxicity evaluation. The most active congeners are 7h in MES screen and (±)-13b in scPTZ screen which displayed ED(50) values of 87 and 110 mg/kg, respectively, as compared to that of STP (ED(50) = 277.7 and 115 mg/kg in MES and scPTZ, respectively). Copyright © 2011 Elsevier Masson SAS. All rights reserved.

Design and Synthesis of Phosphotyrosine Peptidomimetic Prodrugs

PubMed Central

Garrido-Hernandez, Hugo; Moon, Kyung D.; Geahlen, Robert L.; Borch, Richard F.

2008-01-01

A novel approach to the intracellular delivery of aryl phosphates has been developed that utilizes a phosphoramidate-based prodrug approach. The prodrugs contain an ester group that undergoes reductive activation intracellularly with concomitant expulsion of a phosphoramidate anion. This anion undergoes intramolecular cyclization and hydrolysis to generate aryl phosphate exclusively with a t1/2 = ∼ 20 min. Phosphoramidate prodrugs (8-10) of phosphate-containing peptidomimetics that target the SH2 domain were synthesized. Evaluation of these peptidomimetic prodrugs in a growth inhibition assay and, in a cell-based transcriptional assay, demonstrated that the prodrugs had IC50 values in the low micromolar range. Synthesis of phosphorodiamidate analogs containing a P-NH-Ar linker (16 – 18) was also carried out in the hope that the phosphoramidates released might be phosphatase-resistant. Comparable activation rates and cell-based activities were observed for these prodrugs, but the intermediate phosphoramidate dianion underwent spontaneous hydrolysis with a t1/2 = ∼ 30 min. PMID:16722656

Design, microwave-mediated synthesis and biological evaluation of novel 4-aryl(alkyl)amino-3-nitroquinoline and 2,4-diaryl(dialkyl)amino-3-nitroquinolines as anticancer agents.

PubMed

Chauhan, Monika; Rana, Anil; Alex, Jimi Marin; Negi, Arvind; Singh, Sandeep; Kumar, Raj

2015-02-01

Design, microwave-assisted synthesis of novel 4-aryl (alkyl)amino-3-nitroquinoline (1a-1l) and 2,4-diaryl (dialkyl)amino-3-nitroquinolines (2a-2k and 3a) via regioselective and complete nucleophilic substitution of 2,4-dichloro-3-nitroquinoline, respectively in water are presented. The newly synthesized compounds were evaluated for the first time for antiproliferative activity against EGFR overexpressing human lung (A-549 and H-460) and colon (HCT-116-wild type and HCT-116-p53 null) cancer cell lines. Some notions about structure-activity relationships (SAR) are presented. Compounds 2e, 2f, 2j and 3a overall exhibited excellent anticancer activity comparable to erlotinib which was used as a positive control. Molecular modeling studies disclosed the recognition pattern of the compounds and also supported the observed SAR. Copyright © 2014 Elsevier Inc. All rights reserved.

Synthesis and biological evaluation of aryl-oxadiazoles as inhibitors of Mycobacterium tuberculosis.

PubMed

Martinez-Grau, Maria Angeles; Valcarcel, Isabel C Gonzalez; Early, Julie V; Gessner, Richard Klaus; de Melo, Candice Soares; de la Nava, Eva Maria Martin; Korkegian, Aaron; Ovechkina, Yulia; Flint, Lindsay; Gravelle, Anisa; Cramer, Jeff W; Desai, Prashant V; Street, Leslie J; Odingo, Joshua; Masquelin, Thierry; Chibale, Kelly; Parish, Tanya

2018-06-01

Despite increased research efforts to find new treatments for tuberculosis in recent decades, compounds with novel mechanisms of action are still required. We previously identified a series of novel aryl-oxadiazoles with anti-tubercular activity specific for bacteria using butyrate as a carbon source. We explored the structure activity relationship of this series. Structural modifications were performed in all domains to improve potency and physico-chemical properties. A number of compounds displayed sub-micromolar activity against M. tuberculosis utilizing butyrate, but not glucose as the carbon source. Compounds showed no or low cytotoxicity against eukaryotic cells. Three compounds were profiled in mouse pharmacokinetic studies. Plasma clearance was low to moderate but oral exposure suggested solubility-limited drug absorption in addition to first pass metabolism. The presence of a basic nitrogen in the linker slightly increased solubility, and salt formation optimized aqueous solubility. Our findings suggest that the 1,3,4-oxadiazoles are useful tools and warrant further investigation. Copyright © 2018 The Author(s). Published by Elsevier Ltd.. All rights reserved.

Pd-Catalyzed Cross-Coupling Reactions of Amides and Aryl Mesylates

PubMed Central

Dooleweerdt, Karin; Fors, Brett P.; Buchwald, Stephen L.

2010-01-01

A catalyst, based on a biarylphosphine ligand, for the Pd-catalyzed cross-coupling reactions of amides and aryl mesylates is described. This system allows an array of aryl and heteroaryl mesylates to be transformed into the corresponding N-arylamides in moderate to excellent yields. PMID:20420379

40 CFR 721.10367 - Hydroxy-aryl, polymer with substituted benzene, cyanate (generic).

Code of Federal Regulations, 2014 CFR

2014-07-01

... benzene, cyanate (generic). 721.10367 Section 721.10367 Protection of Environment ENVIRONMENTAL PROTECTION... New Uses for Specific Chemical Substances § 721.10367 Hydroxy-aryl, polymer with substituted benzene... substance identified generically as hydroxy-aryl, polymer with substituted benzene, cyanate (PMN P-10-83) is...

40 CFR 721.10367 - Hydroxy-aryl, polymer with substituted benzene, cyanate (generic).

Code of Federal Regulations, 2012 CFR

2012-07-01

... benzene, cyanate (generic). 721.10367 Section 721.10367 Protection of Environment ENVIRONMENTAL PROTECTION... New Uses for Specific Chemical Substances § 721.10367 Hydroxy-aryl, polymer with substituted benzene... substance identified generically as hydroxy-aryl, polymer with substituted benzene, cyanate (PMN P-10-83) is...

40 CFR 721.10367 - Hydroxy-aryl, polymer with substituted benzene, cyanate (generic).

Code of Federal Regulations, 2013 CFR

2013-07-01

... benzene, cyanate (generic). 721.10367 Section 721.10367 Protection of Environment ENVIRONMENTAL PROTECTION... New Uses for Specific Chemical Substances § 721.10367 Hydroxy-aryl, polymer with substituted benzene... substance identified generically as hydroxy-aryl, polymer with substituted benzene, cyanate (PMN P-10-83) is...

Merging Photoredox and Nickel Catalysis: The Direct Synthesis of Ketones via the Decarboxylative Arylation of α-Oxo Acids**

PubMed Central

Chu, Lingling; Lipshultz, Jeffrey M.

2015-01-01

The direct decarboxylative arylation of α-oxo acids has been achieved via synergistic visible light-mediated photoredox and nickel catalyses. This method offers rapid entry to aryl and alkyl ketone architectures from simple α-oxo acid precursors via an acyl radical intermediate. Significant substrate scope is observed with respect to both the oxo acid and arene coupling partners. This mild decarboxylative arylation can also be utilized to efficiently access medicinal agents, as demonstrated by the rapid synthesis of fenofibrate. PMID:26014029

The synthesis of α-aryl-α-aminophosphonates and α-aryl-α-aminophosphine oxides by the microwave-assisted Pudovik reaction

PubMed Central

Tajti, Ádám; Ádám, Anna; Csontos, István; Karaghiosoff, Konstantin; Czugler, Mátyás; Ábrányi-Balogh, Péter

2017-01-01

A family of α-aryl-α-aminophosphonates and α-aryl-α-aminophosphine oxides was synthesized by the microwave-assisted solvent-free addition of dialkyl phosphites and diphenylphosphine oxide, respectively, to imines formed from benzaldehyde derivatives and primary amines. After optimization, the reactivity was mapped, and the fine mechanism was evaluated by DFT calculations. Two α-aminophosphonates were subjected to an X-ray study revealing a racemic dimer formation made through a N–H···O=P intermolecular hydrogen bridges pair. PMID:28179951

Suzuki-Miyaura Cross-Coupling Reactions of Primary Alkyltrifluoroborates with Aryl Chlorides

PubMed Central

Dreher, Spencer D.; Lim, Siang-Ee; Sandrock, Deidre L.; Molander, Gary A.

2009-01-01

Parallel microscale experimentation was used to develop general conditions for the Suzuki-Miyaura cross-coupling of diversely functionalized primary alkyltrifluoroborates with a variety of aryl chlorides. These conditions were found to be amenable to coupling with aryl bromides, iodides, and triflates as well. The conditions that were previously identified through similar techniques to promote the cross-coupling of secondary alkyltrifluoroborates with aryl chlorides were not optimal for the primary alkyltrifluoroborates, thus demonstrating the value of parallel experimentation to develop novel, substrate specific results. PMID:19271726

Indolyl aryl sulfones as HIV-1 non-nucleoside reverse transcriptase inhibitors: role of two halogen atoms at the indole ring in developing new analogues with improved antiviral activity.

PubMed

Regina, Giuseppe La; Coluccia, Antonio; Piscitelli, Francesco; Bergamini, Alberto; Sinistro, Anna; Cavazza, Antonella; Maga, Giovanni; Samuele, Alberta; Zanoli, Samantha; Novellino, Ettore; Artico, Marino; Silvestri, Romano

2007-10-04

Indolyl aryl sulfones bearing the 4,5-difluoro (10) or 5-chloro-4-fluoro (16) substitution pattern at the indole ring were potent inhibitors of HIV-1 WT and the NNRTI-resistant strains Y181C and K103N-Y181C. These compounds were highly effective against the 112 and the AB1 strains in lymphocytes and inhibited at nanomolar concentration the multiplication of the IIIBBa-L strain in macrophages. Compound 16 was exceptionally potent against RT WT and RTs carrying the K103N, Y181I, and L100I mutations.

The aryl hydrocarbon receptor and glucocorticoid receptor interact to activate human metallothionein 2A

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

Sato, Shoko, E-mail: satosho@rs.tus.ac.jp; Shirakawa, Hitoshi, E-mail: shirakah@m.tohoku.ac.jp; Tomita, Shuhei, E-mail: tomita@med.tottori-u.ac.jp

2013-11-15

Although the aryl hydrocarbon receptor (AHR) and glucocorticoid receptor (GR) play essential roles in mammalian development, stress responses, and other physiological events, crosstalk between these receptors has been the subject of much debate. Metallothioneins are classic glucocorticoid-inducible genes that were reported to increase upon treatment with AHR agonists in rodent tissues and cultured human cells. In this study, the mechanism of human metallothionein 2A (MT2A) gene transcription activation by AHR was investigated. Cotreatment with 3-methylcholanthrene and dexamethasone, agonists of AHR and GR respectively, synergistically increased MT2A mRNA levels in HepG2 cells. MT2A induction was suppressed by RNA interference against AHRmore » or GR. Coimmunoprecipitation experiments revealed a physical interaction between AHR and GR proteins. Moreover, chromatin immunoprecipitation assays indicated that AHR was recruited to the glucocorticoid response element in the MT2A promoter. Thus, we provide a novel mechanism whereby AHR modulates expression of human MT2A via the glucocorticoid response element and protein–protein interactions with GR. - Highlights: • Aryl hydrocarbon receptor forms a complex with glucocorticoid receptor in cells. • Human metallothionein gene is regulated by the AHR and GR interaction. • AHR–GR complex binds to glucocorticoid response element in metallothionein gene. • We demonstrated a novel transcriptional mechanism via AHR and GR interaction.« less

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

Helmich, Kate E.; Pereira, Jose Henrique; Gall, Daniel L.

Here, lignin is a combinatorial polymer comprising monoaromatic units that are linked via covalent bonds. Although lignin is a potential source of valuable aromatic chemicals, its recalcitrance to chemical or biological digestion presents major obstacles to both the production of second-generation biofuels and the generation of valuable coproducts from lignin's monoaromatic units. Degradation of lignin has been relatively well characterized in fungi, but it is less well understood in bacteria. A catabolic pathway for the enzymatic breakdown of aromatic oligomers linked via β-aryl ether bonds typically found in lignin has been reported in the bacterium Sphingobium sp. SYK-6. Here, wemore » present x-ray crystal structures and biochemical characterization of the glutathione-dependent β-etherases, LigE and LigF, from this pathway. The crystal structures show that both enzymes belong to the canonical two-domain fold and glutathione binding site architecture of the glutathione S-transferase family. Mutagenesis of the conserved active site serine in both LigE and LigF shows that, whereas the enzymatic activity is reduced, this amino acid side chain is not absolutely essential for catalysis. The results include descriptions of cofactor binding sites, substrate binding sites, and catalytic mechanisms. Because β-aryl ether bonds account for 50–70% of all interunit linkages in lignin, understanding the mechanism of enzymatic β-aryl ether cleavage has significant potential for informing ongoing studies on the valorization of lignin.« less

Leveraging toxicogenomics data to build predictive biomarkers supporting AOP assessment

EPA Science Inventory

Chemicals induce liver cancer in rodents through well characterized adverse outcome pathways (AOPs) that include molecular initiating events (MIEs). In addition to genotoxicity, these include nongenotoxic mechanisms of cytotoxicity and receptor activation (aryl hydrocarbon recept...

Acute biotoxic effect of styrene on rat liver. Correlation with enzyme-mediated mutagenicity of benzpyrene and acrylonitrile.

PubMed

Roberfroid, M; Poncelet, F; Lambotte-Vandepaer, M; Duverger-Van Bogaert, M; de Meester, C; Mercier, M

1978-01-01

Styrene is commonly used in western Europe for the manufacture of plastics suitable for packaging foodstuffs. This report demonstrates that, injected intraperitoneally at a dose as low as 10 mg/kg, styrene modifies the catalytic properties of aryl hydrocarbon hydroxylase by reducing its KM value. A similar effect is reported for two potent chemical carcinogens, 3-methylcholanthrene and benzo(a)pyrene. Ethylbenzene and benzo(e)pyrene and phenobarbital do not produce the same effect. Pretreatments of the rats with chemicals which modify aryl hydrocarbon hydroxylase also increase the capacity of the liver enzymes to activate benzopyrene to a mutagenic intermediate in vitro, as measured by the Ames test for mutagenicity. Exposure to both styrene and the other modifiers of the xenobiotic-metabolizing enzymes could thus influence the carcinogenic and toxic effects of chemicals which are activated by these enzymes. This hypothesis needs further investigation.

Synthesis and biological evaluation of aryl isoxazole derivatives as metabotropic glutamate receptor 1 antagonists: a potential treatment for neuropathic pain.

PubMed

Cho, Gyeong Hi; Kim, TaeHun; Son, Woo Seung; Seo, Seon Hee; Min, Sun-Joon; Cho, Yong Seo; Keum, Gyochang; Jeong, Kyu-Sung; Koh, Hun Yeong; Lee, Jiyoun; Pae, Ae Nim

2015-03-15

Glutamate is the major excitatory neurotransmitter and known to activate the metabotropic and ionotropic glutamate receptors in the brain. Among these glutamate receptors, metabotropic glutamate receptor 1 (mGluR1) has been implicated in various brain disorders including anxiety, schizophrenia and chronic pain. Several studies demonstrated that the blockade of mGluR1 signaling reduced pain responses in animal models, suggesting that mGluR1 is a promising target for the treatment of neuropathic pain. In this study, we have developed mGluR1 antagonists with an aryl isoxazole scaffold, and identify several compounds that are orally active in vivo. We believe that these compounds can serve as a useful tool for the investigation of the role of mGluR1 and a promising lead for the potential treatment of neuropathic pain. Copyright © 2015 Elsevier Ltd. All rights reserved.

Coordination behavior of ligand based on NNS and NNO donors with ruthenium(III) complexes and their catalytic and DNA interaction studies

NASA Astrophysics Data System (ADS)

Manikandan, R.; Viswnathamurthi, P.

2012-11-01

Reactions of 2-acetylpyridine-thiosemicarbazone HL1, 2-acetylpyridine-4-methyl-thiosemicarbazone HL2, 2-acetylpyridine-4-phenyl-thiosemicarbazone HL3 and 2-acetylpyridine-semicarbazone HL4 with ruthenium(III) precursor complexes were studied and the products were characterized by analytical and spectral (FT-IR, electronic, EPR and EI-MS) methods. The ligands coordinated with the ruthenium(III) ion via pyridine nitrogen, azomethine nitrogen and thiolate sulfur/enolate oxygen. An octahedral geometry has been proposed for all the complexes based on the studies. All the complexes are redox active and display an irreversible and quasireversible metal centered redox processes. Further, the catalytic activity of the new complexes has been investigated for the transfer hydrogenation of ketones in the presence of isopropanol/KOH and the Kumada-Corriu coupling of aryl halides with aryl Grignard reagents. The DNA cleavage efficiency of new complexes has also been tested.

A novel aryl acylamidase from Nocardia farcinica hydrolyses polyamide.

PubMed

Heumann, Sonja; Eberl, Anita; Fischer-Colbrie, Gudrun; Pobeheim, Herbert; Kaufmann, Franz; Ribitsch, Doris; Cavaco-Paulo, Artur; Guebitz, Georg M

2009-03-01

An alkali stable polyamidase was isolated from a new strain of Nocardia farcinica. The enzyme consists of four subunits with a total molecular weight of 190 kDa. The polyamidase cleaved amide and ester bonds of water insoluble model substrates like adipic acid bishexylamide and bis(benzoyloxyethyl)terephthalate and hydrolyzed different soluble amides to the corresponding acid. Treatment of polyamide 6 with this amidase led to an increased hydrophilicity based on rising height and tensiometry measurements and evidence of surface hydrolysis of polyamide 6 is shown. In addition to amidase activity, the enzyme showed activity on p-nitrophenylbutyrate. On hexanoamide the amidase exhibited a K(m) value of 5.5 mM compared to 0.07 mM for p-nitroacetanilide. The polyamidase belongs to the amidase signature family and is closely related to aryl acylamidases from different strains/species of Nocardia and to the 6-aminohexanoate-cyclic dimer hydrolase (EI) from Arthrobacter sp. KI72.

Synthesis of a Bicyclic Azetidine with In Vivo Antimalarial Activity Enabled by Stereospecific, Directed C(sp3)-H Arylation.

PubMed

Maetani, Micah; Zoller, Jochen; Melillo, Bruno; Verho, Oscar; Kato, Nobutaka; Pu, Jun; Comer, Eamon; Schreiber, Stuart L

2017-08-16

The development of new antimalarial therapeutics is necessary to address the increasing resistance to current drugs. Bicyclic azetidines targeting Plasmodium falciparum phenylalanyl-tRNA synthetase comprise one promising new class of antimalarials, especially due to their activities against three stages of the parasite's life cycle, but a lengthy synthetic route to these compounds may affect the feasibility of delivering new therapeutic agents within the cost constraints of antimalarial drugs. Here, we report an efficient synthesis of antimalarial compound BRD3914 (EC 50 = 15 nM) that hinges on a Pd-catalyzed, directed C(sp 3 )-H arylation of azetidines at the C3 position. This newly developed protocol exhibits a broad substrate scope and provides access to valuable, stereochemically defined building blocks. BRD3914 was evaluated in P. falciparum-infected mice, providing a cure after four oral doses.

Synthesis and biological evaluation of novel quinazoline-sulfonamides as anti-cancer agents.

PubMed

Poudapally, Suresh; Battu, Shankar; Velatooru, Loka Reddy; Bethu, Murali Satyanarayana; Janapala, Venkateswara Rao; Sharma, Somesh; Sen, Subhabrata; Pottabathini, Narender; Iska, Vijaya Bhaskara Reddy; Katangoor, Vidya

2017-05-01

A robust economic approach to N-(quinazoline-4-yl)sulfonamides was developed and synthesized different aryl, hetero aryl, alkyl and cyclopropyl sulfonamides in excellent yields. All the compounds were evaluated for cytotoxic affinity to SKOV3, DU145, THP1, U937, and COLO205 cell lines. Interesting to find that the bulkiness of substituent at C-2 position of quinazoline forces the molecule to flip around in order to bind in the active site, when compared to the binding preference of previously known quinazoline compounds. Among the 21 compounds synthesized 2b, 2d, 2e, 2h, 2i, 3c, 3d, 3f, 3g and 3h found to be active on all the cell lines tested with IC 50 values <10µg/mL. Performed docking simulations to understand the binding preference of various C-2 substituted quinazoline sulfonamides. Copyright © 2017 Elsevier Ltd. All rights reserved.

Synthesis, crystal structures, computational studies and antimicrobial activity of new designed bis((5-aryl-1,3,4-oxadiazol-2-yl)thio)alkanes

NASA Astrophysics Data System (ADS)

Ahmed, Muhammad Naeem; Sadiq, Beenish; Al-Masoudi, Najim A.; Yasin, Khawaja Ansar; Hameed, Shahid; Mahmood, Tariq; Ayub, Khurshid; Tahir, Muhammad Nawaz

2018-03-01

A new series of bis((5-aryl-1,3,4-oxadiazol-2-yl)thio)alkanes 4-14 have been synthesized via nucleophilic substitution reaction of dihaloalkanes with respective 1,3,4-oxadiazole-2-thiols 3a-f, and characterized by spectroscopic techniques. The structures of 4 and 12 were unambiguously confirmed by single-crystal X-ray diffraction analysis. Density functional theory calculations at B3LYP/6-31 + G(d) level of theory were performed for comparison of X-ray geometric parameters, molecular electrostatic potential (MEP) and frontier molecular orbital analyses of synthesized compounds. MEP analysis revealed that these compounds are nucleophilic in nature. Frontier molecular orbitals (FMOs) analysis of 4-14 was performed for evaluation of kinetic stability. All synthesized compounds were screened in vitro for antimicrobial activity against three bacterial and three fungal strains and showed promising results.

Bimetallic catalysis involving dipalladium(I) and diruthenium(I) complexes.

PubMed

Das, Raj K; Saha, Biswajit; Rahaman, S M Wahidur; Bera, Jitendra K

2010-12-27

Dipalladium(I) and diruthenium(I) compounds bridged by two [{(5,7-dimethyl-1,8-naphthyridin-2-yl)amino}carbonyl]ferrocene (L) ligands have been synthesized. The X-ray structures of [Pd(2)L(2)][BF(4)](2) (1) and [Ru(2)L(2)(CO)(4)][BF(4)](2) (2) reveal dinuclear structures with short metal-metal distances. In both of these structures, naphthyridine bridges the dimetal unit, and the site trans to the metal-metal bond is occupied by weakly coordinating oxygen from the amido fragment. The catalytic utilities of these bimetallic compounds are evaluated. Compound 1 is an excellent catalyst for phosphine-free, Suzuki cross-coupling reactions of aryl bromides with arylboronic acids and provides high yields in short reaction times. Compound 1 is also found to be catalytically active for aryl chlorides, although the corresponding yields are lower. A bimetallic mechanism is proposed, which involves the oxidative addition of aryl bromide across the Pd-Pd bond and the bimetallic reductive elimination of the product. Compound 1 is also an efficient catalyst for the Heck cross-coupling of aryl bromides with styrenes. The mechanism for aldehyde olefination with ethyl diazoacetate (EDA) and PPh(3), catalyzed by 2, has been fully elucidated. It is demonstrated that 2 catalyzes the formation of phosphorane utilizing EDA and PPh(3), which subsequently reacts with aldehyde to produce a new olefin and phosphine oxide. The efficacy of bimetallic complexes in catalytic organic transformations is illustrated in this work.

Novel 5-aryl-1,3-dihydro-indole-2-thiones. potent, orally active progesterone receptor agonists.

PubMed

Fensome, Andrew; Koko, Marci; Wrobel, Jay; Zhang, Puwen; Zhang, Zhiming; Cohen, Jeffrey; Lundeen, Scott; Rudnick, Kelly; Zhu, Yuan; Winneker, Richard

2003-04-07

During the course of our studies on 3,3-disubstituted-5-aryloxindoles derived progesterone receptor (PR) antagonists we discovered that changing the amide funtionality to a thio-amide resulted in compounds displaying potent PR agonist activity. In this communication, the synthesis, structure activity relationships (SAR) and in vivo activity of various 5-arylthio-oxindoles will be discussed.

Base free aryl coupling of diazonium compounds and boronic esters: self-activation allowing an overall highly practical process.

PubMed

Bonin, Hélène; Delbrayelle, Dominique; Demonchaux, Patrice; Gras, Emmanuel

2010-04-21

Boronic esters have long been considered as poor partners in cross-coupling reactions with arene diazoniums. Here is reported an unprecedented application of self-activated boronic esters in a base-free cross-coupling reaction with diazonium salts under mild and user friendly conditions.

Pyridones as NNRTIs against HIV-1 mutants: 3D-QSAR and protein informatics

NASA Astrophysics Data System (ADS)

Debnath, Utsab; Verma, Saroj; Jain, Surabhi; Katti, Setu B.; Prabhakar, Yenamandra S.

2013-07-01

CoMFA and CoMSIA based 3D-QSAR of HIV-1 RT wild and mutant (K103, Y181C, and Y188L) inhibitory activities of 4-benzyl/benzoyl pyridin-2-ones followed by protein informatics of corresponding non-nucleoside inhibitors' binding pockets from pdbs 2BAN, 3MED, 1JKH, and 2YNF were analysed to discover consensus features of the compounds for broad-spectrum activity. The CoMFA/CoMSIA models indicated that compounds with groups which lend steric-cum-electropositive fields in the vicinity of C5, hydrophobic field in the vicinity of C3 of pyridone region and steric field in aryl region produce broad-spectrum anti-HIV-1 RT activity. Also, a linker rendering electronegative field between pyridone and aryl moieties is common requirement for the activities. The protein informatics showed considerable alteration in residues 181 and 188 characteristics on mutation. Also, mutants' isoelectric points shifted in acidic direction. The study offered fresh avenues for broad-spectrum anti-HIV-1 agents through designing new molecules seeded with groups satisfying common molecular fields and concerns of mutating residues.

Design and synthesis of some new 1-phenyl-3/4-[4-(aryl/heteroaryl/alkyl-piperazine1-yl)-phenyl-ureas as potent anticonvulsant and antidepressant agents.

PubMed

Mishra, Chandra Bhushan; Kumari, Shikha; Tiwari, Manisha

2016-05-01

A series of 1-phenyl-3/4-[4-(aryl/heteroaryl/alkyl-piperazine1-yl)-phenyl-urea derivatives (29-42) were designed, synthesized and evaluated for their anticonvulsant activity by using maximal electroshock (MES), subcutaneous pentylenetetrazole (scPTZ) seizure tests. The acute neurotoxicity was checked by rotarod assay. Most of the test compounds were found effective in both seizure tests. Compound 30 (1-{4-[4-(4-chloro-phenyl)-piperazin-1-yl]-phenyl}-3-phenyl-urea) exhibited marked anticonvulsant activity in MES as well as scPTZ tests. The phase II anticonvulsant quantification study of compound 30 indicates the ED50 value of 28.5 mg/kg against MES induced seizures. In addition, this compound also showed considerable protection against pilocarpine induced status epilepticus in rats. Seizures induced by 3-mercaptopropionic acid model and thiosemicarbazide were significantly attenuated by compound 30, which suggested its broad spectrum of anticonvulsant activity. Interestingly, compound 30 displayed better antidepressant activity than standard drug fluoxetine. Moreover, compound 30 appeared as a non-toxic chemical entity in sub-acute toxicity studies.

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.

Fluorination Effects on NOS Inhibitory Activity of Pyrazoles Related to Curcumin.

PubMed

Nieto, Carla I; Cabildo, María Pilar; Cornago, María Pilar; Sanz, Dionisia; Claramunt, Rosa M; Torralba, María Carmen; Torres, María Rosario; Elguero, José; García, José A; López, Ana; Acuña-Castroviejo, Darío

2015-08-28

A series of new (E)-3(5)-[β-(aryl)-ethenyl]-5(3)-phenyl-1H-pyrazoles bearing fluorine atoms at different positions of the aryl group have been synthesized starting from the corresponding β-diketones. All compounds have been characterized by elemental analysis, DSC as well as NMR (¹H, (13)C, (19)F and (15)N) spectroscopy in solution and in solid state. Three structures have been solved by X-ray diffraction analysis, confirming the tautomeric forms detected by solid state NMR. The in vitro study of their inhibitory potency and selectivity on the activity of nNOS and eNOS (calcium-calmodulin dependent) as well as iNOS (calcium-calmodulin independent) isoenzymes is presented. A qualitative structure-activity analysis allowed the establishment of a correlation between the presence/ absence of different substituents with the inhibition data proving that fluorine groups enhance the biological activity. (E)-3(5)-[β-(3-Fluoro-4-hydroxyphenyl)-ethenyl]-5(3)-phenyl-1H-pyrazole (13), is the best inhibitor of iNOS, being also more selective towards the other two isoforms.

Eco-friendly synthesis, in vitro anti-proliferative evaluation, and 3D-QSAR analysis of a novel series of monocationic 2-aryl/heteroaryl-substituted 6-(2-imidazolinyl)benzothiazole mesylates.

PubMed

Racané, Livio; Ptiček, Lucija; Sedić, Mirela; Grbčić, Petra; Kraljević Pavelić, Sandra; Bertoša, Branimir; Sović, Irena; Karminski-Zamola, Grace

2018-04-17

Herein, we describe the synthesis of twenty-one novel water-soluble monocationic 2-aryl/heteroaryl-substituted 6-(2-imidazolinyl)benzothiazole mesylates 3a-3u and present the results of their anti-proliferative assays. Efficient syntheses were achieved by three complementary simple two-step synthetic protocols based on the condensation reaction of aryl/heteroaryl carbaldehydes or carboxylic acid. We developed an eco-friendly synthetic protocol using glycerol as green solvent, particularly appropriate for the condensation of thermally and acid-sensitive heterocycles such as furan, benzofuran, pyrrole, and indole. Screening of anti-proliferative activity was performed on four human tumour cell lines in vitro including pancreatic cancer (CFPAC-1), metastatic colon cancer (SW620), hepatocellular carcinoma (HepG2), and cervical cancer (HeLa), as well as in normal human fibroblast cell lines. All tested compounds showed strong to moderate anti-proliferative activity on tested cell lines depending on the structure containing aryl/heteroaryl moiety coupled to 6-(2-imidazolinyl)benzothiazole moiety. The most potent cytostatic effects on all tested cell lines with [Formula: see text] values ranging from 0.1 to 3.70 [Formula: see text] were observed for benzothiazoles substituted with naphthalene-2-yl 3c, benzofuran-2-yl 3e, indole-3-yl 3j, indole-2-yl 3k, quinoline-2-yl 3s, and quinoline-3-yl 3t and derivatives substituted with phenyl 3a, naphthalene-1-yl 3b, benzothiazole-2-yl 3g, benzothiazole-6-yl 3h, N-methylindole-3-yl 3l, benzimidazole-2-yl 3n, benzimidazole-5(6)-yl 3o, and quinolone-4-yl 3u with [Formula: see text] values ranging from 1.1 to 29.1 [Formula: see text]. Based on obtained anti-proliferative activities, 3D-QSAR models for five cell lines were derived. Molecular volume, molecular surface, the sum of hydrophobic surface areas, molecular mass, and possibility of making dispersion forces were identified by QSAR analyses as molecular properties that are positively correlated with anti-proliferative activity, while compound's capability to accept H-bond was identified as a negatively correlated property. Comparison of molecular properties identified for different cell lines enabled assumptions about similarity of mode of action through which anti-proliferative activities against different cell lines are accomplished. Novel compounds that are predicted to have enhanced activities in comparison with herein presented ones were designed using 3D-QSAR analysis as guideline.

Phenanthridine synthesis through iron-catalyzed intramolecular N-arylation of O-acetyl oxime.

PubMed

Deb, Indubhusan; Yoshikai, Naohiko

2013-08-16

O-Acetyl oximes derived from 2'-arylacetophenones undergo N-O bond cleavage/intramolecular N-arylation in the presence of a catalytic amount of iron(III) acetylacetonate in acetic acid. In combination with the conventional cross-coupling or directed C-H arylation, the reaction offers a convenient route to substituted phenanthridines.

Design, synthesis and biological evaluation of 1H-1,2,3-Triazole-Linked-1H‑Dibenzo[b,h]xanthenes as Inductors of ROS-Mediated Apoptosis in the Breast Cancer Cell Line MCF-7.

PubMed

Bortolot, Carolina S; da S M Forezi, Luana; Marra, Roberta K F; Reis, Marcelo I P; Sa, Barbara V F E; Filho, Ricardo Imbroisi; Ghasemishahrestani, Zeinab; Sola-Penna, Mauro; Zancan, Patricia; Ferreira, Vitor F; de C da Silva, Fernando

2018-05-23

Low molecular weight 1,2,3-triazoles and naphthoquinones are endowed with various types of biological activity, such as against cancer, HIV and bacteria. However, in some cases, the conjugation of these two nuclei considerably increases their biological activities Objective: In this work, we decided to study the synthesis and screening of bis-naphthoquinones and xanthenes tethered to 1,2,3-triazoles against cancer cell lines, specifically the human breast cancer cell line MCF-7. Starting from lawsone and aryl-1H-1,2,3-triazole-4-carbaldehydes (10a-h) several new 7-(1-aryl-1H-1,2,3-triazol-4-yl)-6H-dibenzo[b,h]xanthene-5,6,8,13(7H)-tetraones (12a-h) and 3,3'-((1-aryl-1H-1,2,3-triazol-4-yl)methylene)bis(2-hydroxynaphthalene-1,4-diones) 11a-h were synthesized and evaluated for their cytotoxic activities using the human breast cancer cell line MCF-7 and the non-tumor cell line MCF10A as control. We performed test of cell viability, cell proliferation, intracellular ATP content and cell cytometry to determine reactive oxygen species (ROS) formation. Based on these results, we found that compound 12a promote ROS production, interfering with energy metabolism, cell viability and proliferation, and thus promoting an whole cell damage. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Synthesis and Anticancer Activity of 2-(Alkyl-, Alkaryl-, Aryl-, Hetaryl-)-[1,2,4]triazolo[1,5-c]quinazolines

PubMed Central

Kovalenko, Sergiy I.; Antypenko, Lyudmyla M.; Bilyi, Andriy K.; Kholodnyak, Sergiy V.; Karpenko, Olexandr V.; Antypenko, Olexii M.; Mykhaylova, Natalya S.; Los, Tetyana I.; Kolomoets, Olexandra S.

2013-01-01

The combinatorial library of novel potential anticancer agents, namely, 2-(alkyl-, alkaryl-, aryl-, hetaryl-)[1,2,4]triazolo[1,5-c]quinazolines, was synthesized by the heterocyclization of the alkyl-, alkaryl-, aryl-, hetarylcarboxylic acid (3H-quinazoline-4-ylidene)hydrazides by oxidative heterocyclization of the 4-(arylidenehydrazino)quinazolines using bromine, and by the heterocyclization of N-(2-cyanophenyl)formimidic acid ethyl ester. The optimal method for synthesis of the s-triazolo[1,5-c]quinazolines appeared to be cyclocondensation of the corresponding carboxylic acid (3H-quinazoline-4-ylidene)hydrazides. The compounds’ structures were established by 1H, 13C NMR, LC- and EI-MS analysis. The in vitro screening of anticancer activity determined the most active compound to be 3,4,5-trimethoxy-N′-[quinazolin-4(3H)-ylidene]benzohydrazide (3.20) in micromolar concentrations with the GI50 level (MG_MID, GI50 is 2.29). Thus, the cancer cell lines whose growth is greatly inhibited by compound 3.20 are: non-small cell lung cancer (NCI-H522, GI50=0.34), CNS (SF-295, GI50=0.95), ovarian (OVCAR-3, GI50=0.33), prostate (PC-3, GI50=0.56), and breast cancer (MCF7, GI50=0.52), leukemia (K-562, GI50=0.41; SR, GI50=0.29), and melanoma (MDA-MB-435, GI50=0.31; SK-MEL-5, GI50=0.74; UACC-62, GI50=0.32). SAR-analysis is also discussed. PMID:23833709

Synthesis of 1,2-cis-2-C-branched aryl-C-glucosides via desulfurization of carbohydrate based hemithioacetals

PubMed Central

Mebrahtu, Fanuel M; Manana, Mandlenkosi M; Madumo, Kagiso; Sokamisa, Mokela S

2015-01-01

Summary 1-C and 2-C-branched carbohydrates are present as substructures in a number of biologically important compounds. Although the synthesis of such carbohydrate derivatives is extensively studied, the synthesis of 1,2-cis-2-C-branched C-, S-, and N-glycosides is less explored. In this article a synthetic strategy for the synthesis of 1,2-cis-2-C-branched-aryl-C-glucosides is reported via a hydrogenolytic desulfurization of suitably orientated carbohydrate based hemithioacetals. 1,2-cis-2-Hydroxymethyl and 2-carbaldehyde of aryl-C-glucosides have been synthesized using the current strategy in very good yields. The 2-carbaldehyde-aryl-C-glucosides have been identified as suitable substrates for the stereospecific preparation of 2,3-unsaturated-aryl-C-glycosides (Ferrier products). PMID:26124859

General and mild Ni(0)-catalyzed α-arylation of ketones using aryl chlorides.

PubMed

Fernández-Salas, José A; Marelli, Enrico; Cordes, David B; Slawin, Alexandra M Z; Nolan, Steven P

2015-03-02

A general methodology for the α-arylation of ketones using a nickel catalyst has been developed. The new well-defined [Ni(IPr*)(cin)Cl] (1 c) pre-catalyst showed great efficiency for this transformation, allowing the coupling of a wide range of ketones, including acetophenone derivatives, with various functionalised aryl chlorides. This cinnamyl-based Ni-N-heterocyclic carbene (NHC) complex has demonstrated a different behaviour to previously reported NHC-Ni catalysts. Preliminary mechanistic studies suggest a Ni(0)/Ni(II) catalytic cycle to be at play. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Understanding and Exploitation of Neighboring Heteroatom Effect for the Mild N-Arylation of Heterocycles with Diaryliodonium Salts under Aqueous Conditions: A Theoretical and Experimental Mechanistic Study.

PubMed

Bihari, Tamás; Babinszki, Bence; Gonda, Zsombor; Kovács, Szabolcs; Novák, Zoltán; Stirling, András

2016-07-01

The mechanism of arylation of N-heterocycles with unsymmetric diaryliodonium salts is elucidated. The fast and efficient N-arylation reaction is interpreted in terms of the bifunctionality of the substrate: The consecutive actions of properly oriented Lewis base and Brønsted acid centers in sufficient proximity result in the fast and efficient N-arylation. The mechanistic picture points to a promising synthetic strategy where suitably positioned nucleophilic and acidic centers enable functionalization, and it is tested experimentally.

Palladium-catalyzed cross-coupling of aryl chlorides and triflates with sodium cyanate: A practical synthesis of unsymmetrical ureas

PubMed Central

Vinogradova, Ekaterina V.; Fors, Brett P.; Buchwald, Stephen L.

2012-01-01

An efficient method for palladium-catalyzed cross-coupling of aryl chlorides and triflates with sodium cyanate is reported. The protocol allows for the synthesis of unsymmetrical N,N'-di- and N,N,N'-trisubstituted ureas in one pot, and is tolerant of a wide range of functional groups. Insight into the mechanism of aryl isocyanate formation is gleaned through studies of the transmetallation and reductive elimination steps of the reaction, including the first demonstration of reductive elimination from an arylpalladium isocyanate complex to produce an aryl isocyanate. PMID:22716197

Redox shuttle additives for lithium-ion batteries

DOEpatents

Zhang, Lu; Zhang, Zhengcheng; Amine, Khalil

2017-03-21

An electro lye includes a compound of Formula I or IA: where each instance of R.sup.1 is independently H, alkyl, alkoxy, alkenyl, aryl, heteroaryl, or cycloalkyl; each instance of R.sup.2 is independently H, alkyl, alkoxy, alkenyl, aryl, heteroaryl, or cycloalkyl; each instance of R.sup.3 is independently H, alkyl, alkenyl, aryl, or cycloalkyl; each instance of R.sup.4 is independently H, halogen, CN, NO.sub.2, phosphate, alkyl, alkenyl, aryl, heteroaryl, or cycloalkyl; x is 1, 2, 3, 4, or 5; y is 1 or 2; and z is 0, 1, 2, 3, or 4. ##STR00001##

Utilization of acidic α-amino acids as acyl donors: an effective stereo-controllable synthesis of aryl-keto α-amino acids and their derivatives.

PubMed

Wang, Lei; Murai, Yuta; Yoshida, Takuma; Okamoto, Masashi; Tachrim, Zetryana Puteri; Hashidoko, Yasuyuki; Hashimoto, Makoto

2014-05-16

Aryl-keto-containing α-amino acids are of great importance in organic chemistry and biochemistry. They are valuable intermediates for the construction of hydroxyl α-amino acids, nonproteinogenic α-amino acids, as well as other biofunctional components. Friedel-Crafts acylation is an effective method to prepare aryl-keto derivatives. In this review, we summarize the preparation of aryl-keto containing α-amino acids by Friedel-Crafts acylation using acidic α-amino acids as acyl-donors and Lewis acids or Brönsted acids as catalysts.

Cu-Click Compatible Triazabutadienes To Expand the Scope of Aryl Diazonium Ion Chemistry.

PubMed

Cornali, Brandon M; Kimani, Flora W; Jewett, John C

2016-10-07

Triazabutadienes can be used to readily generate reactive aryl diazonium ions under mild, physiologically relevant conditions. These conditions are compatible with a range of functionalities that do not tolerate traditional aryl diazonium ion generation. To increase the utility of this aryl diazonium ion releasing chemistry an alkyne-containing triazabutadiene was synthesized. The copper-catalyzed azide-alkyne cycloaddition ("Cu-click") reaction was utilized to modify the alkyne-containing triazabutadiene and shown to be compatible with the nitrogen-rich triazabutadiene. One of the triazole products was tethered to a fluorophore, thus enabling the direct fluorescent labeling of a model protein.

An efficient synthesis of bis-1,3-(3'-aryl-N-heterocycl-1'-yl)arenes as CCC-NHC pincer ligand precursors.

PubMed

Howell, Tyler O; Huckaba, Aron J; Hollis, T Keith

2014-05-02

A report that demonstrated an efficient methodology for the arylation of imidazoles has been extended to bis(N-heterocyclic) compounds. Using bis(aryl) iodonium salts provides high-yielding access to CCC-NHC ligand precursors in a single step. Examples of arylation using various iodonium salts are reported herein with an investigation into the factors governing their relative rate of reactivity. The metalation of one of these compounds using Zr(NMe2)4 and its subsequent treatment with [Pt(COD)Cl2] to yield a transmetalated product are reported.

Hypoxia perturbs aryl hydrocarbon receptor signaling and CYP1A1 expression induced by PCB 126 in human skin and liver-derived cell lines.

PubMed

Vorrink, Sabine U; Severson, Paul L; Kulak, Mikhail V; Futscher, Bernard W; Domann, Frederick E

2014-02-01

The aryl hydrocarbon receptor (AhR) is an important mediator of toxic responses after exposure to xenobiotics including 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and dioxin-like polychlorinated biphenyls (PCBs). Activation of AhR responsive genes requires AhR dimerization with the aryl hydrocarbon receptor nuclear translocator (ARNT), a heterodimeric partner also shared by the hypoxia-inducible factor-1α (HIF-1α) protein. TCDD-stimulated AhR transcriptional activity can be influenced by hypoxia; however, it less well known whether hypoxia interferes with AhR transcriptional transactivation in the context of PCB-mediated AhR activation in human cells. Elucidation of this interaction is important in liver hepatocytes which extensively metabolize ingested PCBs and experience varying degrees of oxygen tension during normal physiologic function. This study was designed to assess the effect of hypoxia on AhR transcriptional responses after exposure to 3,3',4,4',5-pentachlorobiphenyl (PCB 126). Exposure to 1% O2 prior to PCB 126 treatment significantly inhibited CYP1A1 mRNA and protein expression in human HepG2 and HaCaT cells. CYP1A1 transcriptional activation was significantly decreased upon PCB 126 stimulation under conditions of hypoxia. Additionally, hypoxia pre-treatment reduced PCB 126 induced AhR binding to CYP1 target gene promoters. Importantly, ARNT overexpression rescued cells from the inhibitory effect of hypoxia on XRE-luciferase reporter activity. Therefore, the mechanism of interference of the signaling crosstalk between the AhR and hypoxia pathways appears to be at least in part dependent on ARNT availability. Our results show that AhR activation and CYP1A1 expression induced by PCB 126 were significantly inhibited by hypoxia and hypoxia might therefore play an important role in PCB metabolism and toxicity. Copyright © 2013 Elsevier Inc. All rights reserved.

Synthesis and pharmacological activity of new carbonyl derivatives of 1-aryl-2-iminoimidazolidine: part 2. Synthesis and pharmacological activity of 1,6-diaryl-5,7(1H)dioxo-2,3-dihydroimidazo[1,2-a][1,3,5]triazines.

PubMed

Matosiuk, Dariusz; Fidecka, Sylwia; Antkiewicz-Michaluk, Lucyna; Lipkowski, Janusz; Dybala, Izabela; Koziol, Anna E

2002-09-01

Synthesis and pharmacological activity of 1,6-diaryl-5,7(1H)dioxo-2,3-dihydroimidazo-[1,2-a][1,3,5]triazines (C) are presented. The title compounds were obtained from 1-arylimidazolinurea derivatives in cyclization reaction with difunctional carbonyl reagents--phosgene (method I) or carbonyldiimidazole (CDI) (method II). Their molecular structures were confirmed by the X-ray analysis of 1-phenyl-6-(4-chlorophenyl)-5,7(1H)-dioxo-2,3-dihydroimidazo[1,2-a][1,3,5]triazine (C2) crystals. Compounds C exhibited significant depressive action on the central nervous system (CNS) of the laboratory animals, correlated with very low acute toxicity (LD(50) > 2000 mg kg(-1) i.p.), and showed antinociceptive activity in behavioural models. Reversion of this effect by small dose of naloxone (5 mg kg(-1)) can suggest opioid-like mechanism of antinociception produced by these and other carbonyl derivatives of 1-aryl-2-iminoimidazolidine. Additionally, an effect on the serotonin neurotransmission pathway was also observed. The receptor mechanism of activity for investigated compounds was confirmed only for the opioid mu receptor in binding affinity assay test. Same tests performed for the serotonin 5-HT(2) and benzodiazepine BZD receptors showed no affinity for tested compounds. The opioid-like and serotonergic activities are similar to these described earlier for chain carbonyl 1-aryl-2-iminoimidazolidine derivatives containing urea moiety, mainly due to similar chemical structure, although compounds C are not able to adopt any of the higher energy conformations of urea derivatives. Rigid location of aromatic ring (Ar') at N6, acting as a spacer blocking any direct access to the carbonyl groups (e.g. through the hydrogen bonding), could be responsible for lack of affinity toward 5-HT(2) expressed in the binding assay test. Copyright 2002 Editions scienctifiques et médicales Elsevier SAS

Observation of inductive effects that cause a change in the rate-determining step for the conversion of rhenium azides to imido complexes.

PubMed

Travia, Nicholas E; Xu, Zhenggang; Keith, Jason M; Ison, Elon A; Fanwick, Phillip E; Hall, Michael B; Abu-Omar, Mahdi M

2011-10-17

The cationic oxorhenium(V) complex [Re(O)(hoz)(2)(CH(3)CN)][B(C(6)F(5))(4)] [1; Hhoz = 2-(2'-hydroxyphenyl)-2-oxazoline] reacts with aryl azides (N(3)Ar) to give cationic cis-rhenium(VII) oxoimido complexes of the general formula [Re(O)(NAr)(hoz)(2)][B(C(6)F(5))(4)] [2a-2f; Ar = 4-methoxyphenyl, 4-methylphenyl, phenyl, 3-methoxyphenyl, 4-chlorophenyl, and 4-(trifluoromethyl)phenyl]. The kinetics of formation of 2 in CH(3)CN are first-order in both azide (N(3)Ar) and oxorhenium(V) complex 1, with second-order rate constants ranging from 3.5 × 10(-2) to 1.7 × 10(-1) M(-1) s(-1). A strong inductive effect is observed for electron-withdrawing substituents, leading to a negative Hammett reaction constant ρ = -1.3. However, electron-donating substituents on phenyl azide deviate significantly from this trend. Enthalpic barriers (ΔH(‡)) determined by the Eyring-Polanyi equation are in the range 14-19 kcal mol(-1) for all aryl azides studied. However, electron-donating 4-methoxyphenyl azide exhibits a large negative entropy of activation, ΔS(‡) = -21 cal mol(-1) K(-1), which is in sharp contrast to the near zero ΔS(‡) observed for phenyl azide and 4-(trifluoromethyl)phenyl azide. The Hammett linear free-energy relationship and the activation parameters support a change in the mechanism between electron-withdrawing and electron-donating aryl azides. Density functional theory predicts that the aryl azides coordinate via N(α) and extrude N(2) directly. For the electron-withdrawing substituents, N(2) extrusion is rate-determining, while for the electron-donating substituents, the rate-determining step becomes the initial attack of the azide. The barriers for these two steps are inverted in their order with respect to the Hammett σ values; thus, the Hammett plot appears with a break in its slope.

A transition-metal-free synthesis of arylcarboxyamides from aryl diazonium salts and isocyanides.

PubMed

Xia, Zhonghua; Zhu, Qiang

2013-08-16

A transition-metal-free carboxyamidation process, using aryl diazonium tetrafluoroborates and isocyanides under mild conditions, has been developed. This novel conversion was initiated by a base and solvent induced aryl radical, followed by radical addition to isocyanide and single electron transfer (SET) oxidation, affording the corresponding arylcarboxyamide upon hydration of the nitrilium intermediate.

Aryl-Aryl Interactions in Designed Peptide Folds: Spectroscopic Characteristics and Placement Issues for Optimal Structure Stabilization

PubMed Central

Anderson, Jordan M.; Kier, Brandon; Jurban, Brice; Byrne, Aimee; Shu, Irene; Eidenschink, Lisa A.; Shcherbakov, Alexander A.; Hudson, Mike; Fesinmeyer, R. M.; Andersen, Niels H.

2017-01-01

We have extended our studies of Trp/Trp to other Aryl/Aryl through-space interactions that stabilize hairpins and other small polypeptide folds. Herein we detail the NMR and CD spectroscopic features of these types of interactions. NMR data remains the best diagnostic for characterizing the common T-shape orientation. Designated as an edge-to-face (EtF or FtE) interaction, large ring current shifts are produced at the edge aryl ring hydrogens and, in most cases, large exciton couplets appear in the far UV circular dichroic (CD) spectrum. The preference for the face aryl in FtE clusters is W≫Y≥F (there are some exceptions in the Y/F order); this sequence corresponds to the order of fold stability enhancement and always predicts the amplitude of the lower energy feature of the exciton couplet in the CD spectrum. The CD spectra for FtE W/W, W/Y, Y/W, and Y/Y pairs all include an intense feature at 225–232 nm. An additional couplet feature seen for W/Y, W/F, Y/Y and F/Y clusters, is a negative feature at 197–200 nm. Tyr/Tyr (as well as F/Y and F/F) interactions produce much smaller exciton couplet amplitudes. The Trp-cage fold was employed to search for the CD effects of other Trp/Trp and Trp/Tyr cluster geometries: several were identified. In this account, we provide additional examples of the application of cross-strand aryl/aryl clusters for the design of stable β-sheet models and a scale of fold stability increments associated with all possible FtE Ar/Ar clusters in several structural contexts. PMID:26850220

Human butyrylcholinesterase components differ in aryl acylamidase activity.

PubMed

Montenegro, María F; María, T Moral-Naranjo; de la Cadena, María Páez; Campoy, Francisco J; Muñoz-Delgado, Encarnación; Vidal, Cecilio J

2008-04-01

Apart from its esterase activity, butyrylcholinesterase (BuChE) displays aryl acylamidase (AAA) activity able to hydrolyze o-nitroacetanilide (ONA) and its trifluoro-derivative (F-ONA). We report here that, despite amidase and esterase sites residing in the same protein, in human samples depleted of acetylcholinesterase the ratio of amidase to esterase activity varied depending on the source of BuChE. The much faster degradation of ONA and F-ONA by BuChE monomers (G1) of colon and kidney than by the tetramers (G4) suggests aggregation-driven differences in the AAA site between single and polymerized subunits. The similar ratio of F-ONAto butyrylthiocholine hydrolysis by serum G1 and G4 forms support structural differences in the amidase site according to the source of BuChE. The changing ratios of amidase to esterase activities in the human sources probably arise from post-translational modifications in BuChE subunits, the specific proportion of monomers and oligomers and the variable capacity of the tetramers for degrading ONA and F-ONA. The elevated amidase activity of BuChE monomers and the scant activity of the tetramers justify the occurrence of single BuChE subunits in cells as a means to sustain the AAA activity of BuChE which otherwise could be lost by tetramerization.

Selective Synthesis of 5- or 6-Aryl Octahydrocyclopenta[b]pyrroles from a Common Precursor Through Control of Competing Pathways in a Pd-Catalyzed Reaction

PubMed Central

Ney, Joshua E.; Wolfe, John P.

2009-01-01

The Pd/phosphine-catalyzed reaction of 1 with aryl bromides leads to the selective synthesis of either 6-aryl octahydrocyclopenta[b]pyrroles (3), the corresponding 5-aryl isomers 5, diarylamine 2, or hexahydrocyclopenta[b]pyrrole 4 depending on the structure of the phosphine ligand. These transformations are effective with a variety of different aryl bromides, and provide 3-5 with excellent levels of diastereoselectivity (dr ≥ 20:1). The changes in product distribution are believed to derive from the influence of Pd-catalyst structure on the relative rates of reductive elimination, β-hydride elimination, alkene insertion, and alkene dissociation processes in a mechanistically complex reaction. The effect of phosphine ligand structure on product distribution is described in detail, along with analysis of a proposed mechanism for these transformations. PMID:15954769

Arynes, diaryliodonium salts and azine N-oxides in transition metal-free electrophilic N-arylation

NASA Astrophysics Data System (ADS)

Bugaenko, D. I.; Karchava, A. V.; Yurovskaya, M. A.

2018-03-01

The main approach to the synthesis of aromatic and heteroaromatic amines is based on palladium- and copper-catalyzed N-arylation reactions. Although these methods are highly efficient and provide extensive opportunities for the synthesis of (het)arylamines with various structures and properties, they have some limitations related to the catalysts used and reaction conditions. This review addresses alternative approaches to N-(het)arylation that have been extensively developed in the past decade and are based on the use of arynes, diaryliodonium salts and azine N-oxides as electrophilic (het)arylating agents. Because of mild reaction conditions and no need for catalysts and strong bases, these N-(het)arylation methods are attractive for various synthetic applications and open up new possibilities for the preparation of valuable organic compounds inaccessible via traditional catalytic methods. The attention is focussed on publications of the last decade. The bibliography includes 112 references.

Divergent unprotected peptide macrocyclisation by palladium-mediated cysteine arylation.

PubMed

Rojas, Anthony J; Zhang, Chi; Vinogradova, Ekaterina V; Buchwald, Nathan H; Reilly, John; Pentelute, Bradley L; Buchwald, Stephen L

2017-06-01

Macrocyclic peptides are important therapeutic candidates due to their improved physicochemical properties in comparison to their linear counterparts. Here we detail a method for a divergent macrocyclisation of unprotected peptides by crosslinking two cysteine residues with bis-palladium organometallic reagents. These synthetic intermediates are prepared in a single step from commercially available aryl bis-halides. Two bioactive linear peptides with cysteine residues at i , i + 4 and i , i + 7 positions, respectively, were cyclised to introduce a diverse array of aryl and bi-aryl linkers. These two series of macrocyclic peptides displayed similar linker-dependent lipophilicity, phospholipid affinity, and unique volume of distributions. Additionally, one of the bioactive peptides showed target binding affinity that was predominantly affected by the length of the linker. Collectively, this divergent strategy allowed rapid and convenient access to various aryl linkers, enabling the systematic evaluation of the effect of appending unit on the medicinal properties of macrocyclic peptides.

Effect of acyl chain length on selective biocatalytic deacylation on O-aryl glycosides and separation of anomers.

PubMed

Aggarwal, Neha; Arya, Anu; Mathur, Divya; Singh, Sukhdev; Tyagi, Abhilash; Kumar, Rajesh; Rana, Neha; Singh, Rajendra; Prasad, Ashok K

2014-04-01

It has been demonstrated that Lipozyme® TL IM (Thermomyces lanuginosus lipase immobilised on silica) can selectively deacylate the ester function involving the C-5' hydroxyl group of α-anomers over the other acyl functions of anomeric mixture of peracylated O-aryl α,β-D-ribofuranoside. The analysis of results of biocatalytic deacylation reaction revealed that the reaction time decreases with the increase in the acyl chain length from C1 to C4. The unique selectivity of Lipozyme® TL IM has been harnessed for the separation of anomeric mixture of peracylated O-aryl α,β-D-ribofuranosides, The lipase mediated selective deacylation methodology has been used for the synthesis of O-aryl α-D-ribofuranosides and O-aryl β-D-ribofuranosides in pure forms, which can be used as chromogenic substrate for the detection of pathogenic microbial parasites containing glycosidases. Copyright © 2014. Published by Elsevier Inc.

Constitutive expression of the AHR signaling pathway in a bovine mammary epithelial cell line and modulation by dioxin-like PCB and other AHR ligands.

PubMed

Girolami, Flavia; Spalenza, Veronica; Manzini, Livio; Carletti, Monica; Nebbia, Carlo

2015-01-05

Environmental pollutants, such as dioxin-like (DL) PCBs, benzo(a) pyrene (B[a]P), and flavonoids are aryl hydrocarbon receptor (AHR) ligands and may be excreted in dairy milk. The expression of AHR-target genes, particularly those involved in xenobiotic biotransformation, and their modulation by two DL-PCBs, B[a]P, and β-naphthoflavone was investigated in a bovine mammary epithelial cell line (BME-UV). As assessed by quantitative PCR, BME-UV cells expressed a functional AHR signaling pathway. All the AHR ligands induced a concentration-related increase in the transcription of cytochrome P450 1A1 and 1B1, known to be implicated in the bioactivation of several xenobiotics. Conversely, genes encoding for antioxidant and detoxifying enzymes, like quinone oxidoreductase or glutathione S-transferase A2, were not affected or even depressed. This study demonstrates the occurrence and the modulation by different AHR-ligands of genes involved in xenobiotic metabolism in BME-UV cells, with the potential generation of (re) active metabolites that may damage mammary tissue and/or affect animal or human health via the contaminated milk. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Nickel-catalyzed coupling reaction of alkyl halides with aryl Grignard reagents in the presence of 1,3-butadiene: mechanistic studies of four-component coupling and competing cross-coupling reactions† †Electronic supplementary information (ESI) available: Detailed experimental and computational results, procedures, characterization data, copies of NMR charts, and crystallographic data. CCDC 1572238. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c7sc04675h

PubMed Central

Fukuoka, Asuka; Yokoyama, Wataru; Min, Xin; Hisaki, Ichiro; Kuniyasu, Hitoshi

2018-01-01

We describe the mechanism, substituent effects, and origins of the selectivity of the nickel-catalyzed four-component coupling reactions of alkyl fluorides, aryl Grignard reagents, and two molecules of 1,3-butadiene that affords a 1,6-octadiene carbon framework bearing alkyl and aryl groups at the 3- and 8-positions, respectively, and the competing cross-coupling reaction. Both the four-component coupling reaction and the cross-coupling reaction are triggered by the formation of anionic nickel complexes, which are generated by the oxidative dimerization of two molecules of 1,3-butadiene on Ni(0) and the subsequent complexation with the aryl Grignard reagents. The C–C bond formation of the alkyl fluorides with the γ-carbon of the anionic nickel complexes leads to the four-component coupling product, whereas the cross-coupling product is yielded via nucleophilic attack of the Ni center toward the alkyl fluorides. These steps are found to be the rate-determining and selectivity-determining steps of the whole catalytic cycle, in which the C–F bond of the alkyl fluorides is activated by the Mg cation rather than a Li or Zn cation. ortho-Substituents of the aryl Grignard reagents suppressed the cross-coupling reaction leading to the selective formation of the four-component products. Such steric effects of the ortho-substituents were clearly demonstrated by crystal structure characterizations of ate complexes and DFT calculations. The electronic effects of the para-substituent of the aryl Grignard reagents on both the selectivity and reaction rates are thoroughly discussed. The present mechanistic study offers new insight into anionic complexes, which are proposed as the key intermediates in catalytic transformations even though detailed mechanisms are not established in many cases, and demonstrates their synthetic utility as promising intermediates for C–C bond forming reactions, providing useful information for developing efficient and straightforward multicomponent reactions. PMID:29719693

Efficient synthesis and antimicrobial activity of some novel S-β-d-glucosides of 5-aryl-1,2,4-triazole-3-thiones derivatives.

PubMed

Ji, Dan; Lu, JunRui; Lu, BoWei; Xin, ChunWei; Mu, JiangBei; Li, JianFa; Peng, ChunYong; Bao, XiuRong

2013-04-01

A series of 3-S-β-d-glucosides-4-arylideneamino-5-aryl-1,2,4-triazoles were rationally designed and synthesized according to the principle of superposition of bioactive substructures by the combination of 1,2,4-triazole, Schiff base and glucosides. The structures of the target compounds have been characterized by (1)H NMR, (13)C NMR, IR, MS and HRMS. All the newly synthesized compounds have been evaluated for their antimicrobial activities in vitro against Staphylococcus aureus (ATCC 6538), Escherichia coli (ATCC 8099) as well as Monilia albican (ATCC 10231). The bioactive assay showed that most of the tested compounds displayed variable inhibitory effects on the growth of the Gram-positive bacterial strain (Staphylococcus aureus), Gram-negative bacterial strains (Escherichia coli) and fungal strains (Monilia albican). All the target compounds exhibited better antifungal activity than antibacterial activity. Especially, compounds 6b, 6c, 6f, 6j, 6k and 6l showed excellent activity against fungus Monilia albican with MIC values of 16 μg/mL. Copyright © 2013 Elsevier Ltd. All rights reserved.

Inhibition of Siderophore Biosynthesis in Mycobacterium tuberculosis with Nucleoside Bisubstrate Analogues: Structure–Activity Relationships of the Nucleobase Domain of 5′-O-[N-(Salicyl)sulfamoyl]adenosine

PubMed Central

Neres, João; Labello, Nicholas P.; Somu, Ravindranadh V.; Boshoff, Helena I.; Wilson, Daniel J.; Vannada, Jagadeshwar; Chen, Liqiang; Barry, Clifton E.; Bennett, Eric M.; Aldrich, Courtney C.

2009-01-01

5′-O-[N-(salicyl)sulfamoyl]adenosine (Sal-AMS) is a prototype for a new class of antitubercular agents that inhibit the aryl acid adenylating enzyme (AAAE) known as MbtA involved in biosynthesis of the mycobactins. Herein, we report the structure-based design, synthesis, biochemical, and biological evaluation of a comprehensive and systematic series of analogues, exploring the structure–activity relationship of the purine nucleobase domain of Sal-AMS. Significantly, 2-phenyl-Sal-AMS derivative 26 exhibited exceptionally potent antitubercular activity with an MIC99 under iron-deficient conditions of 0.049 µM while the N-6-cyclopropyl-Sal-AMS 16 led to improved potency and to a 64-enhancement in activity under iron-deficient conditions relative to iron-replete conditions, a phenotype concordant with the designed mechanism of action. The most potent MbtA inhibitors disclosed here display in vitro antitubercular activity superior to most current first line TB drugs, and these compounds are also expected to be useful against a wide range of pathogens that require aryl-capped siderphores for virulence. PMID:18690677

Antiplasmodial Activity of [(Aryl)arylsulfanylmethyl]Pyridine▿ †‡

PubMed Central

Kumar, Sanjay; Das, Sajal Kumar; Dey, Sumanta; Maity, Pallab; Guha, Mithu; Choubey, Vinay; Panda, Gautam; Bandyopadhyay, Uday

2008-01-01

A series of [(aryl)arylsufanylmethyl]pyridines (AASMP) have been synthesized. These compounds inhibited hemozoin formation, formed complexes (KD = 12 to 20 μM) with free heme (ferriprotoporphyrin IX) at a pH close to the pH of the parasite food vacuole, and exhibited antimalarial activity in vitro. The inhibition of hemozoin formation may develop oxidative stress in Plasmodium falciparum due to the accumulation of free heme. Interestingly, AASMP developed oxidative stress in the parasite, as evident from the decreased level of glutathione and increased formation of lipid peroxide, H2O2, and hydroxyl radical (·OH) in P. falciparum. AASMP also caused mitochondrial dysfunction by decreasing mitochondrial potential (ΔΨm) in malaria parasite, as measured by both flow cytometry and fluorescence microscopy. Furthermore, the generation of ·OH may be mainly responsible for the antimalarial effect of AASMP since ·OH scavengers such as mannitol, as well as spin trap α-phenyl-n-tertbutylnitrone, significantly protected P. falciparum from AASMP-mediated growth inhibition. Cytotoxicity testing of the active compounds showed selective activity against malaria parasite with selectivity indices greater than 100. AASMP also exhibited profound antimalarial activity in vivo against chloroquine resistant P. yoelii. Thus, AASMP represents a novel class of antimalarial. PMID:18025110

Understanding the properties of chitosan aryl substituted thioureas in their role and potential as antibacterial agents

NASA Astrophysics Data System (ADS)

Khairul, Wan M.; Daud, Adibah Izzati; Ismail, Noraznawati

2018-02-01

In this study, the effort was to design and synthesize a series of thiourea-chitosan derivatives featuring five aryl substituted members namely N-chitosan-N'-(4-nitrobenzoyl) thiourea (1), N-chitosan-N'-(4-chlorobenzoyl) thiourea (2), N-chitosan-N'-(4-methylbenzoyl) thiourea (3), N-chitosan-N'-(2-iodobenzoyl) thiourea (4), and N-chitosan-N'-(2-methylbenzoyl) thiourea (5) via SN2 reaction pathway having different donating and withdrawing groups. Their molecular structures were then characterised by FT-IR, UV-Vis, and thermogravimetric analysis (TGA). The antimicrobial activities of these derivatives against four species bacteria Bacillus cereus, Staphylococcus aureus, Salmonella typhi, and Escherichia coli of both Gram-positive and Gram-negative type bacteria at minimum concentration 6mg/ml were carried out to investigate their potential as antibacterial agents. Compound 1 exhibited specific activity as it can only inhibit Gram-positive bacteria while other compounds 2-5 showed broad range spectrum activity as they were able to inhibit both Gram-positive and Gram-negative bacteria. Therefore, 1-5 showed good antibacterial activity and have high potential to be further developed as active materials in pharmaceutical interests.

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.

Discovery of N-(4-aryl-5-aryloxy-thiazol-2-yl)-amides as potent RORγt inverse agonists.

PubMed

Wang, Yonghui; Yang, Ting; Liu, Qian; Ma, Yingli; Yang, Liuqing; Zhou, Ling; Xiang, Zhijun; Cheng, Ziqiang; Lu, Sijie; Orband-Miller, Lisa A; Zhang, Wei; Wu, Qianqian; Zhang, Kathleen; Li, Yi; Xiang, Jia-Ning; Elliott, John D; Leung, Stewart; Ren, Feng; Lin, Xichen

2015-09-01

A novel series of N-(4-aryl-5-aryloxy-thiazol-2-yl)-amides as RORγt inverse agonists was discovered. Binding mode analysis of a RORγt partial agonist (2c) revealed by co-crystal structure in RORγt LBD suggests that the inverse agonists do not directly interfere with the interaction between H12 and the RORγt LBD. Detailed SAR exploration led to identification of potent RORγt inverse agonists such as 3m with a pIC50 of 8.0. Selected compounds in the series showed reasonable activity in Th17 cell differentiation assay as well as low intrinsic clearance in mouse liver microsomes. Copyright © 2015 Elsevier Ltd. All rights reserved.

Synthesis and dynamic NMR study of ketenimines derived from tert-butyl isocyanide, alkyl 2-arylamino-2-oxo-acetates, and dialkyl acetylenedicarboxylates.

PubMed

Yavari, Issa; Nasiri, Farough; Djahaniani, Horieh

2004-01-01

The adduct produced in the reaction between tert-butyl isocyanide and dialkyl acetylenedicarboxylates was trapped by alkyl 2-arylamino-2-oxo-acetates. When the aryl group is 2-methyl-6-nitrophenyl or 2,6-di-isopropylphenyl, the product exists as two stable rotamers at room temperature as a result of restricted rotation around the Ar-N single bond. When the aryl group is 1-naphthyl or 8-quinolinyl, dynamic NMR effects are observed in the 1H NMR spectra. The calculated free-energy of activation for interconversion of the rotational isomers in 1-naphthyl and 8-quinolinyl derivatives amounts to about 99+/-2 and 68.5+/-2 kJ mol(-1), respectively.

An endogenous aryl hydrocarbon receptor ligand inhibits proliferation and migration of human ovarian cancer cells

PubMed Central

Jiang, Yi-Zhou; Dai, Cai-Feng; Patankar, Manish S.; Song, Jia-Sheng; Zheng, Jing

2013-01-01

The aryl hydrocarbon receptor (AhR), a ligand-activated transcription factor mediates many biological processes. Herein, we investigated if 2-(1′H-indole-3′-carbonyl)-thiazole-4-carboxylic acid methyl ester (ITE, an endogenous AhR ligand) regulated proliferation and migration of human ovarian cancer cells via AhR. We found that AhR was widely present in many histotypes of ovarian cancer tissues. ITE suppressed OVCAR-3 cell proliferation and SKOV-3 cell migration in vitro, which were blocked by AhR knockdown. ITE also suppressed OVCAR-3 cell growth in mice. These data suggest that the ITE might potentially be used for therapeutic intervention for at least a subset of human ovarian cancer. PMID:23851185

Dimension-controlled assemblies of anion-responsive π-electronic systems bearing aryl substituents with fan-shaped geometries.

PubMed

Lakshmi, Vellanki; Haketa, Yohei; Yamakado, Ryohei; Yasuda, Nobuhiro; Maeda, Hiromitsu

2017-03-30

Pyrrole-4-aryl-substituted dipyrrolyldiketone BF 2 complexes as anion-responsive π-electronic molecules were synthesized via a 3,5-dimethylpyrrole precursor. Mesophases were observed in derivatives that possessed long alkyl chains on the pyrrole-4-aryl groups along with their anion complexes as ion-pairing assemblies in combination with appropriate cations.

Asymmetric Direct 1,2-Addition of Aryl Grignard Reagents to Aryl Alkyl Ketones.

PubMed

Osakama, Kazuki; Nakajima, Makoto

2016-01-15

The enantioselective addition of Grignard reagents to ketones was promoted by a BINOL derivative bearing alkyl chains at the 3,3'-positions. This is the first asymmetric direct aryl Grignard addition to ketones reported to date. A variety of tertiary diaryl alcohols could be obtained in high yields and enantioselectivities without using any other metal source.

Asymmetric Aryl Polyhedral Oligomeric SilSesquioxanes (ArPOSS) with Enhanced Solubility (Preprint)

DTIC Science & Technology

2011-03-23

by reaction of an aryl Grignard or lithium reagent with SiCl4 under reaction conditions s imilar to those previously reported [22]. The aryl...cooling to room temperature, this Grignard reagent w as added via canula to a SiCl 4 (25.1 g, 0.148 m ol) THF (70 mL) solution and stirred overnight

Synthesis of Quinolines through Three-Component Cascade Annulation of Aryl Diazonium Salts, Nitriles, and Alkynes.

PubMed

Wang, Hao; Xu, Qian; Shen, Sheng; Yu, Shouyun

2017-01-06

An efficient and rapid synthesis of multiply substituted quinolines is described. This method is enabled by a three-component cascade annulation of readily available aryl diazonium salts, nitriles, and alkynes. This reaction is catalyst- and additive-free. Various aryl diazonium salts, nitriles, and alkynes can participate in this transformation, and the yields are up to 83%.

Asymmetric synthesis of 5-arylcyclohexenones by rhodium(I)-catalyzed conjugate arylation of racemic 5-(trimethylsilyl)cyclohexenone with arylboronic acids.

PubMed

Chen, Qian; Kuriyama, Masami; Soeta, Takahiro; Hao, Xinyu; Yamada, Ken-ichi; Tomioka, Kiyoshi

2005-09-29

[reaction: see text] A catalytic asymmetric conjugate arylation of racemic 5-(trimethylsilyl)cyclohex-2-enone with arylboronic acids was catalyzed by 3 mol % chiral amidophosphane- or BINAP-Rh(I) in dioxane-water (10:1) to afford trans- and cis-3-aryl-5-(trimethylsilyl)cyclohexanones in high enantioselectivity. Dehydrosilylation of the product mixture with cupric chloride in DMF gave 5-arylcyclohex-2-enones with up to 93% ee in good yield. Enantiofacial selectivity with chiral phosphane-Rh(I) exceeds the trans-diastereoselectivity that is maintained in the achiral or racemic phosphane-Rh(I)-catalyzed conjugate arylation of 5-(trimethylsilyl)cyclohexenone.

Copper-Mediated Fluorination of Arylboronate Esters. Identification of a Copper(III) Fluoride Complex

PubMed Central

Fier, Patrick S.; Luo, Jingwei; Hartwig, John F.

2013-01-01

A method for the direct conversion of arylboronate esters to aryl fluorides under mild conditions with readily available reagents is reported. Tandem reactions have also been developed for the fluorination of arenes and aryl bromides through aryl-boronate ester intermediates. Mechanistic studies suggest that this fluorination reaction occurs through facile oxidation of Cu(I) to Cu(III) followed by rate-limiting transmetallation of a bound arylboronate to Cu(III). Fast C-F reductive elimination is proposed to occur from an aryl-copper(III)-fluoride complex. Cu(III) intermediates have been generated independently and identified by NMR spectroscopy and ESI-MS. PMID:23384209

A Modular Flow Design for the meta‐Selective C−H Arylation of Anilines

PubMed Central

Gemoets, Hannes P. L.; Laudadio, Gabriele; Verstraete, Kirsten; Hessel, Volker

2017-01-01

Abstract Described herein is an effective and practical modular flow design for the meta‐selective C−H arylation of anilines. The design consists of four continuous‐flow modules (i.e., diaryliodonium salt synthesis, meta‐selective C−H arylation, inline copper extraction, and aniline deprotection) which can be operated either individually or consecutively to provide direct access to meta‐arylated anilines. With a total residence time of 1 hour, the desired product could be obtained in high yield and excellent purity without the need for column chromatography, and the residual copper content meets the standards for parenterally administered pharmaceutical substances. PMID:28543979

Preparation of water-soluble magnetic nanocrystals using aryl diazonium salt chemistry.

PubMed

Griffete, Nébéwia; Herbst, Frédéric; Pinson, Jean; Ammar, Souad; Mangeney, Claire

2011-02-16

A novel and facile methodology for the in situ surface functionalization of Fe(3)O(4) nanoparticles is proposed, based on the use of aryl diazonium salts chemistry. The grafting reaction involves the formation of diazoates in a basic medium. These species are unstable and dediazonize along a homolytic pathway to give aryl radicals which further react with the Fe(3)O(4) NPs during their formation and stop their growth. Advantages of the present approach rely not only on the simplicity, rapidity, and efficiency of the procedure but also on the formation of strong Fe(3)O(4)-aryl surface bonds, highly suitable for further applications.

Polymerization initated at sidewalls of carbon nanotubes

NASA Technical Reports Server (NTRS)

Tour, James M. (Inventor); Hudson, Jared L. (Inventor); Krishnamoorti, Ramanan (Inventor); Yurekli, Koray (Inventor); Mitchell, Cynthia A. (Inventor)

2011-01-01

The present invention is directed to aryl halide (such as aryl bromide) functionalized carbon nanotubes that can be utilized in anionic polymerization processes to form polymer-carbon nanotube materials with improved dispersion ability in polymer matrices. In this process the aryl halide is reacted with an alkyllithium species or is reacted with a metal to replace the aryl-bromine bond with an aryl-lithium or aryl-metal bond, respectively. It has further been discovered that other functionalized carbon nanotubes, after deprotonation with a deprotonation agent, can similarly be utilized in anionic polymerization processes to form polymer-carbon nanotube materials. Additionally or alternatively, a ring opening polymerization process can be performed. The resultant materials can be used by themselves due to their enhanced strength and reinforcement ability when compared to their unbound polymer analogs. Additionally, these materials can also be blended with pre-formed polymers to establish compatibility and enhanced dispersion of nanotubes in otherwise hard to disperse matrices resulting in significantly improved material properties. The resultant polymer-carbon nanotube materials can also be used in drug delivery processes due to their improved dispersion ability and biodegradability, and can also be used for scaffolding to promote cellular growth of tissue.

Expedient synthesis of C-aryl carbohydrates by consecutive biocatalytic benzoin and aldol reactions.

PubMed

Hernández, Karel; Parella, Teodor; Joglar, Jesús; Bujons, Jordi; Pohl, Martina; Clapés, Pere

2015-02-16

The introduction of aromatic residues connected by a C-C bond into the non-reducing end of carbohydrates is highly significant for the development of innovative structures with improved binding affinity and selectivity (e.g., C-aril-sLex). In this work, an expedient asymmetric "de novo" synthetic route to new aryl carbohydrate derivatives based on two sequential stereoselectively biocatalytic carboligation reactions is presented. First, the benzoin reaction of aromatic aldehydes to dimethoxyacetaldehyde is conducted, catalyzed by benzaldehyde lyase from Pseudomonas fluorescens biovar I. Then, the α-hydroxyketones formed are reduced by using NaBH4 yielding the anti diol. After acetal hydrolysis, the aldol addition of dihydroxyacetone, hydroxyacetone, or glycolaldehyde catalyzed by the stereocomplementary D-fructose-6-phosphate aldolase and L-rhamnulose-1-phosphate aldolase is performed. Both aldolases accept unphosphorylated donor substrates, avoiding the need of handling the phosphate group that the dihydroxyacetone phosphate-dependent aldolases require. In this way, 6-C-aryl-L-sorbose, 6-C-aryl-L-fructose, 6-C-aryl-L-tagatose, and 5-C-aryl-L-xylose derivatives are prepared by using this methodology. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Studies toward the oxidative and reductive activation of C-S bonds in 2'-S-aryl-2'-thiouridine derivatives.

PubMed

Rayala, Ramanjaneyulu; Giuglio-Tonolo, Alain; Broggi, Julie; Terme, Thierry; Vanelle, Patrice; Theard, Patricia; Médebielle, Maurice; Wnuk, Stanislaw F

2016-04-21

Studies directed toward the oxidative and reductive desulfurization of readily available 2'- S -aryl-2'-thiouridine derivatives were investigated with the prospect to functionalize the C2'-position of nucleosides. The oxidative desulfurization-difluorination strategy was successful on 2-(arylthio)alkanoate surrogates, while extension of the combination of oxidants and fluoride sources was not an efficient fluorination protocol when applied to 2'- S -aryl-2'-thiouridine derivatives, resulting mainly in C5-halogenation of the pyrimidine ring and C2'-monofluorination without desulfurization. Cyclic voltammetry of 2'-arylsulfonyl-2'-deoxyuridines and their 2'-fluorinated analogues showed that cleavage of the arylsulfone moiety could occur, although at relatively high cathodic potentials. While reductive-desulfonylation of 2'-arylsulfonyl-2'-deoxyuridines with organic electron donors (OEDs) gave predominantly base-induced furan type products, chemical (OED) and electrochemical reductive-desulfonylation of the α-fluorosulfone derivatives yielded the 2'-deoxy-2'-fluorouridine and 2',3'-didehydro-2',3'-dideoxy-2'-fluorouridine derivatives. These results provided good evidence of the generation of a C2'-anion through carbon-sulfur bond cleavage, opening new horizons for the reductive-functionalization approaches in nucleosides.

Studies toward the oxidative and reductive activation of C-S bonds in 2'-S-aryl-2'-thiouridine derivatives

PubMed Central

Rayala, Ramanjaneyulu; Giuglio-Tonolo, Alain; Broggi, Julie; Terme, Thierry; Vanelle, Patrice; Theard, Patricia; Médebielle, Maurice; Wnuk, Stanislaw F.

2016-01-01

Studies directed toward the oxidative and reductive desulfurization of readily available 2'-S-aryl-2'-thiouridine derivatives were investigated with the prospect to functionalize the C2'-position of nucleosides. The oxidative desulfurization-difluorination strategy was successful on 2-(arylthio)alkanoate surrogates, while extension of the combination of oxidants and fluoride sources was not an efficient fluorination protocol when applied to 2'-S-aryl-2'-thiouridine derivatives, resulting mainly in C5-halogenation of the pyrimidine ring and C2'-monofluorination without desulfurization. Cyclic voltammetry of 2'-arylsulfonyl-2'-deoxyuridines and their 2'-fluorinated analogues showed that cleavage of the arylsulfone moiety could occur, although at relatively high cathodic potentials. While reductive-desulfonylation of 2'-arylsulfonyl-2'-deoxyuridines with organic electron donors (OEDs) gave predominantly base-induced furan type products, chemical (OED) and electrochemical reductive-desulfonylation of the α-fluorosulfone derivatives yielded the 2'-deoxy-2'-fluorouridine and 2',3'-didehydro-2',3'-dideoxy-2'-fluorouridine derivatives. These results provided good evidence of the generation of a C2'-anion through carbon-sulfur bond cleavage, opening new horizons for the reductive-functionalization approaches in nucleosides. PMID:27019535

Apoptosis inducing factor (AIF) mediates lethal redox stress induced by menadione.

PubMed

Wiraswati, Hesti Lina; Hangen, Emilie; Sanz, Ana Belén; Lam, Ngoc-Vy; Reinhardt, Camille; Sauvat, Allan; Mogha, Ariane; Ortiz, Alberto; Kroemer, Guido; Modjtahedi, Nazanine

2016-11-22

Mitochondrial apoptosis inducing factor (AIF) is a redox-active enzyme that participates to the biogenesis/maintenance of complex I of the respiratory chain, yet also contributes to catabolic reactions in the context of regulated cell death when AIF translocates to the cytosol and to the nucleus. Here we explore the contribution of AIF to cell death induced by menadione (2-methyl-1,4-naphtoquinone; also called vitamin K3) in conditions in which this pro-oxidant does not cause the mitochondrial release of AIF, yet causes caspase-independent cell killing. Depletion of AIF from human cancer cells reduced the cytotoxicity of menadione. This cytoprotective effect was accompanied by the maintenance of high levels of reduced glutathione (GSH), which are normally depleted by menadione. In addition, AIF depletion reduced the arylation of cellular proteins induced by menadione. This menadione-triggered arylation, which can be measured by a fluorescence assay, is completely suppressed by addition of exogenous glutathione or N-acetyl cysteine. Complex I inhibition by Rotenone did not mimic the cytoprotective action of AIF depletion. Altogether, these results are compatible with the hypothesis that mitochondrion-sessile AIF facilitates lethal redox cycling of menadione, thereby precipitating protein arylation and glutathione depletion.

Apoptosis inducing factor (AIF) mediates lethal redox stress induced by menadione

PubMed Central

Wiraswati, Hesti Lina; Hangen, Emilie; Sanz, Ana Belén; Lam, Ngoc-Vy; Reinhardt, Camille; Sauvat, Allan; Mogha, Ariane; Ortiz, Alberto

2016-01-01

Mitochondrial apoptosis inducing factor (AIF) is a redox-active enzyme that participates to the biogenesis/maintenance of complex I of the respiratory chain, yet also contributes to catabolic reactions in the context of regulated cell death when AIF translocates to the cytosol and to the nucleus. Here we explore the contribution of AIF to cell death induced by menadione (2-methyl-1,4-naphtoquinone; also called vitamin K3) in conditions in which this pro-oxidant does not cause the mitochondrial release of AIF, yet causes caspase-independent cell killing. Depletion of AIF from human cancer cells reduced the cytotoxicity of menadione. This cytoprotective effect was accompanied by the maintenance of high levels of reduced glutathione (GSH), which are normally depleted by menadione. In addition, AIF depletion reduced the arylation of cellular proteins induced by menadione. This menadione-triggered arylation, which can be measured by a fluorescence assay, is completely suppressed by addition of exogenous glutathione or N-acetyl cysteine. Complex I inhibition by Rotenone did not mimic the cytoprotective action of AIF depletion. Altogether, these results are compatible with the hypothesis that mitochondrion-sessile AIF facilitates lethal redox cycling of menadione, thereby precipitating protein arylation and glutathione depletion. PMID:27738311

The 3,7-diazabicyclo[3.3.1]nonane scaffold for subtype selective nicotinic acetylcholine receptor (nAChR) ligands. Part 1: the influence of different hydrogen bond acceptor systems on alkyl and (hetero)aryl substituents.

PubMed

Eibl, Christoph; Tomassoli, Isabelle; Munoz, Lenka; Stokes, Clare; Papke, Roger L; Gündisch, Daniela

2013-12-01

3,7-Diazabicyclo[3.3.1]nonane is a naturally occurring scaffold interacting with nicotinic acetylcholine receptors (nAChRs). When one nitrogen of the 3,7-diazabicyclo[3.3.1]nonane scaffold was implemented in a carboxamide motif displaying a hydrogen bond acceptor (HBA) functionality, compounds with higher affinities and subtype selectivity for α4β2(∗) were obtained. The nature of the HBA system (carboxamide, sulfonamide, urea) had a strong impact on nAChR interaction. High affinity ligands for α4β2(∗) possessed small alkyl chains, small un-substituted hetero-aryl groups or para-substituted phenyl ring systems along with a carboxamide group. Electrophysiological responses of selected 3,7-diazabicyclo[3.3.1]nonane derivatives to Xenopus oocytes expressing various nAChR subtypes showed diverse activation profiles. Compounds with strongest agonistic profiles were obtained with small alkyl groups whereas a shift to partial agonism/antagonism was observed for aryl substituents. Copyright © 2013 Elsevier Ltd. All rights reserved.

Synthesis of aryl pyrazole via Suzuki coupling reaction, in vitro mushroom tyrosinase enzyme inhibition assay and in silico comparative molecular docking analysis with Kojic acid.

PubMed

Channar, Pervaiz Ali; Saeed, Aamer; Larik, Fayaz Ali; Batool, Bakhtawar; Kalsoom, Saima; Hasan, M M; Erben, Mauricio F; El-Seedi, Hesham R; Ali, Musrat; Ashraf, Zaman

2018-04-30

Aryl pyrazoles are well recognized class of heterocyclic compounds found in several commercially available drugs. Owing to their significance in medicinal chemistry, in this current account we have synthesized a series of suitably substituted aryl pyrazole by employing Suzuki cross-coupling reaction. All compounds were evaluated for inhibition of mushroom tyrosinase enzyme both in vitro and in silico. Compound 3f (IC 50  = 1.568 ± 0.01 µM) showed relatively better potential compared to reference kojic acid (IC 50  = 16.051 ± 1.27 µM). A comparative docking studies showed that compound 3f have maximum binding affinity against mushroom tyrosinase (PDBID: 2Y9X) with binding energy value (-6.90 kcal/mol) as compared to Kojic acid. The 4-methoxy group in compound 3f shows 100% interaction with Cu. Compound 3f displayed hydrogen binding interaction with His61 and His94 at distance of 1.71 and 1.74 Å which might be responsible for higher activity compared to Kojic acid. Copyright © 2018 Elsevier Inc. All rights reserved.

Reaction of singlet-excited 2,3-diazabicyclo[2.2.2]oct-2-ene and tert-butoxyl radicals with aryl-substituted benzofuranones.

PubMed

Lundgren, Cecilia Vannesjö; Koner, Apurba L; Tinkl, Michael; Pischel, Uwe; Nau, Werner M

2006-03-03

5,7-Di-tert-butyl-3-aryl-3H-benzofuran-2-ones are lactones with potential antioxidant activity, owing to their abstractable benzylic C-H hydrogens. The fluorescence quenching of the azoalkane 2,3-diazabicyclo[2.2.2]oct-2-ene (DBO), an established probe for the hydrogen-donor propensity of chain-breaking antioxidants, was investigated for 16 aryl-substituted benzofuranone derivatives [m,m-(CF3)2, p-CN, m-CN, p-CF3, p-COOCH3, m-CF3, p-Cl, p-F, H, m-CH3, p-CH3, m,p-(CH3)2, p-OCH3, o-CH3, o-CF3, o,m-(CH3)2]. Analysis of the rate data in terms of a linear free energy relationship yielded a reaction constant of rho = +0.35. This implies that n,pi*-excited DBO acts as nucleophilic species. In contrast, hydrogen abstraction of tert-butoxyl radicals from the benzofuranones was accelerated by electron-donating substituents (rho = -0.23), in conformity with the electrophilic character of oxygen-centered alkoxyl radicals. Possible implications for the optimization of the hydrogen-donor propensity of antioxidants through structural variation are discussed.

Purification and enzymatic characterization of secretory glycoside hydrolase family 3 (GH3) aryl β-glucosidases screened from Aspergillus oryzae genome.

PubMed

Kudo, Kanako; Watanabe, Akira; Ujiie, Seiryu; Shintani, Takahiro; Gomi, Katsuya

2015-12-01

By a global search of the genome database of Aspergillus oryzae, we found 23 genes encoding putative β-glucosidases, among which 10 genes with a signal peptide belonging to glycoside hydrolase family 3 (GH3) were overexpressed in A. oryzae using the improved glaA gene promoter. Consequently, crude enzyme preparations from three strains, each harboring the genes AO090038000223 (bglA), AO090103000127 (bglF), and AO090003001511 (bglJ), showed a substrate preference toward p-nitrophenyl-β-d-glucopyranoside (pNPGlc) and thus were purified to homogeneity and enzymatically characterized. All the purified enzymes (BglA, BglF, and BglJ) preferentially hydrolyzed aryl β-glycosides, including pNPGlc, rather than cellobiose, and these enzymes were proven to be aryl β-glucosidases. Although the specific activity of BglF toward all the substrates tested was significantly low, BglA and BglJ showed appreciably high activities toward pNPGlc and arbutin. The kinetic parameters of BglA and BglJ for pNPGlc suggested that both the enzymes had relatively higher hydrolytic activity toward pNPGlc among the fungal β-glucosidases reported. The thermal and pH stabilities of BglA were higher than those of BglJ, and BglA was particularly stable in a wide pH range (pH 4.5-10). In contrast, BglJ was the most heat- and alkaline-labile among the three β-glucosidases. Furthermore, BglA was more tolerant to ethanol than BglJ; as a result, it showed much higher hydrolytic activity toward isoflavone glycosides in the presence of ethanol than BglJ. This study suggested that the mining of novel β-glucosidases exhibiting higher activity from microbial genome sequences is of great use for the production of beneficial compounds such as isoflavone aglycones. Copyright © 2015 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Effects of Developmental Activation of the Aryl Hydrocarbon Receptor by 2,3,7,8-Tetrachlorodibenzo-p-dioxin on Long-term Self-renewal of Murine Hematopoietic Stem Cells.

PubMed

Laiosa, Michael D; Tate, Everett R; Ahrenhoerster, Lori S; Chen, Yuhong; Wang, Demin

2016-07-01

Human epidemiological and animal studies suggest that developmental exposure to contaminants that activate the aryl hydrocarbon receptor (AHR) lead to suppression of immune system function throughout life. The persistence of immune deficiency throughout life suggests that the cellular target of AHR activation is a fetal hematopoietic progenitor or stem cell. The aim of this study was to identify the effects of transplacental exposure to an AHR agonist on long-term self-renewal of fetal hematopoietic stem cells. Pregnant C57BL/6 or AHR+/- mice were exposed to the AHR agonist, 2,3,7,8-tetra-​chlorodibenzo-p-dioxin (TCDD). On day 14 of gestation, hematopoietic progenitors from wild-type or AHR-deficient fetuses were placed into in vitro T-lymphocyte differentiation cultures to identify the effects of transplacental TCDD on AHR activation in the fetus. We next analyzed the fetal hematopoietic progenitor cells for changes in reactive oxygen species (ROS). Finally, hematopoietic progenitors from fetuses exposed transplacentally to TCDD were mixed 1:1 with cells from congenic controls and used to reconstitute lethally irradiated recipients for analysis of long-term self-renewal potential. Our findings suggested that the effects of TCDD on the developing hematopoietic system were mediated by direct AHR activation in the fetus. Furthermore, developmental AHR activation by TCDD increased ROS in the fetal hematopoietic stem cells, and the elevated ROS was associated with a reduced capacity of the TCDD-exposed fetal cells to compete with control cells in a mixed competitive irradiation/reconstitution assay. Our findings indicate that AHR activation by TCDD in the fetus during pregnancy leads to impairment of long-term self-renewal of hematopoietic stem cells. Laiosa MD, Tate ER, Ahrenhoerster LS, Chen Y, Wang D. 2016. Effects of developmental activation of the aryl hydrocarbon receptor by 2,3,7,8-tetrachlorodibenzo-p-dioxin on long-term self-renewal of murine hematopoietic stem cells. Environ Health Perspect 124:957-965; http://dx.doi.org/10.1289/ehp.1509820.

A one-pot radioiodination of aryl amines via stable diazonium salts: preparation of 125I-imaging agents.

PubMed

Sloan, Nikki L; Luthra, Sajinder K; McRobbie, Graeme; Pimlott, Sally L; Sutherland, Andrew

2017-10-05

An operationally simple, one-pot, two-step tandem procedure that allows the incorporation of radioactive iodine into aryl amines via stable diazonium salts is described. The mild conditions are tolerant of various functional groups and substitution patterns, allowing late-stage, rapid access to a wide range of 125 I-labelled aryl compounds and SPECT radiotracers.

Synthesis of radiolabelled aryl azides from diazonium salts: experimental and computational results permit the identification of the preferred mechanism.

PubMed

Joshi, Sameer M; de Cózar, Abel; Gómez-Vallejo, Vanessa; Koziorowski, Jacek; Llop, Jordi; Cossío, Fernando P

2015-05-28

Experimental and computational studies on the formation of aryl azides from the corresponding diazonium salts support a stepwise mechanism via acyclic zwitterionic intermediates. The low energy barriers associated with both transition structures are compatible with very fast and efficient processes, thus making this method suitable for the chemical synthesis of radiolabelled aryl azides.

Bioorthogonal Diversification of Peptides through Selective Ruthenium(II)-Catalyzed C-H Activation.

PubMed

Schischko, Alexandra; Ren, Hongjun; Kaplaneris, Nikolaos; Ackermann, Lutz

2017-02-01

Methods for the chemoselective modification of amino acids and peptides are powerful techniques in biomolecular chemistry. Among other applications, they enable the total synthesis of artificial peptides. In recent years, significant momentum has been gained by exploiting palladium-catalyzed cross-coupling for peptide modification. Despite major advances, the prefunctionalization elements on the coupling partners translate into undesired byproduct formation and lengthy synthetic operations. In sharp contrast, we herein illustrate the unprecedented use of versatile ruthenium(II)carboxylate catalysis for the step-economical late-stage diversification of α- and β-amino acids, as well as peptides, through chemo-selective C-H arylation under racemization-free reaction conditions. The ligand-accelerated C-H activation strategy proved water-tolerant and set the stage for direct fluorescence labelling as well as various modes of peptide ligation with excellent levels of positional selectivity in a bioorthogonal fashion. The synthetic utility of our approach is further demonstrated by twofold C-H arylations for the complexity-increasing assembly of artificial peptides within a multicatalytic C-H activation manifold. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Interrelated Roles for the Aryl Hydrocarbon Receptor and Hypoxia Inducible Factor-1α in the Immune Response to Infection

PubMed Central

Wagage, Sagie; Hunter, Christopher A.

2015-01-01

Cells of the immune system utilize multiple mechanisms to respond to environmental signals and recent studies have demonstrated roles for two closely related proteins, the aryl hydrocarbon receptor (AHR) and hypoxia inducible factor-1α (HIF1α), in these processes. The AHR is a transcription factor that is activated by diverse ligands found in the diet and environmental pollution as well as by microbial and host-derived products. In contrast, HIF1α is a transcription factor that is active under low oxygen conditions and mediates cellular responses to hypoxia. These evolutionarily conserved proteins have roles in the interrelated processes of metabolism, tumorigenesis, and vascular development. Additionally, the AHR and HIF1α have multiple effects on innate and adaptive immunity. This article provides an overview of the biology of these transcription factors and reviews the effects of AHR and HIF1α signaling on immunity to infection. There are many parallels between these two pathways and their functions highlight the importance of AHR and HIF1α activity particularly at barrier surfaces in coordinating responses to pathogens.

5-Acetyl-6-methyl-4-aryl-3,4-dihydropyrimidin-2(1H)-ones: As potent urease inhibitors; synthesis, in vitro screening, and molecular modeling study.

PubMed

Shamim, Shahbaz; Khan, Khalid Mohammed; Salar, Uzma; Ali, Farman; Lodhi, Muhammad Arif; Taha, Muhammad; Khan, Farman Ali; Ashraf, Sajda; Ul-Haq, Zaheer; Ali, Muhammad; Perveen, Shahnaz

2018-02-01

5-Acetyl-6-methyl-4-aryl-3,4-dihydropyrimidin-2(1H)-ones 1-43 were synthesized in a "one-pot" three component reaction and structurally characterized by various spectroscopic techniques such as 1 H, 13 C NMR, EI-MS, HREI-MS, and IR. All compounds were evaluated for their in vitro urease inhibitory activity. It is worth mentioning that except derivatives 1, 11, 12, and 14, all were found to be more potent than the standard thiourea (IC 50  = 21.25 ± 0.15 µM) and showed their urease inhibitory potential in the range of IC 50  = 3.70 ± 0.5-20.14 ± 0.1 µM. Structure-activity relationship (SAR) was rationalized by looking at the varying structural features of the molecules. However, molecular modeling study was performed to confirm the binding interactions of the molecules (ligand) with the active site of enzyme. Copyright © 2017 Elsevier Inc. All rights reserved.

Synthesis of aryl thioethers through the N-chlorosuccinimide-promoted cross-coupling reaction of thiols with Grignard reagents.

PubMed

Cheng, Jun-Hao; Ramesh, Chintakunta; Kao, Hsin-Lun; Wang, Yu-Jen; Chan, Chien-Ching; Lee, Chin-Fa

2012-11-16

A convenient one-pot approach for the synthesis of aryl sulfides through the coupling of thiols with Grignard reagents in the presence of N-chlorosuccinimide is described. The sulfenylchlorides were formed when thiols were treated with N-chlorosuccinimide, and the resulting sulfenylchlorides were then directly reacted with Grignard reagents to provide aryl sulfides in good to excellent yields under mild reaction conditions. Functional groups including ester, fluoro, and chloro are tolerated by the reaction conditions employed. It is important to note that this method has a short reaction time (30 min in total) and represents an alternative approach for the synthesis of aryl sulfides over the existing protocols.

Stabilizing and destabilizing effects of phenylalanine --> F5-phenylalanine mutations on the folding of a small protein.

PubMed

Woll, Matthew G; Hadley, Erik B; Mecozzi, Sandro; Gellman, Samuel H

2006-12-20

We report a systematic evaluation of phenylalanine-to-pentafluorophenylalanine (Phe --> F5-Phe) mutants for the 35-residue chicken villin headpiece subdomain (c-VHP), the hydrophobic core of which features a cluster of three Phe side chains (residues 6, 10, and 17). Phe --> F5-Phe mutations are interesting because aryl-perfluoroaryl interactions of optimal geometry are intrinsically more favorable than aryl-aryl interactions and because perfluoroaryl units are more hydrophobic than are analogous aryl units. One mutant, Phe-10 --> F5-Phe, provides enhanced tertiary structural stability relative to the native sequence. The other six mutants analyzed caused a decrease in stability.

Design, Synthesis, and Validation of an Effective, Reusable Silicon-Based Transfer Agent for Room-Temperature Pd-Catalyzed Cross-Coupling Reactions of Aryl and Heteroaryl Chlorides with Readily Available Aryl Lithium Reagents

PubMed Central

Martinez-Solorio, Dionicio; Melillo, Bruno; Sanchez, Luis; Liang, Yong; Lam, Erwin; Houk, K. N.; Smith, Amos B.

2016-01-01

A reusable silicon-based transfer agent (1) has been designed, synthesized, and validated for effective room-temperature palladium-catalyzed cross-coupling reactions (CCRs) of aryl and heteroaryl chlorides with readily accessible aryl lithium reagents. The crystalline, bench-stable siloxane transfer agent (1) is easily prepared via a one-step protocol. Importantly, this “green” CCR protocol circumvents prefunctionalization, isolation of organometallic cross-coupling partners, and/or stoichiometric waste aside from LiCl. DFT calculations support a σ-bond metathesis mechanism during transmetalation and lead to insights on the importance of the CF3 groups. PMID:26835838

A Modular Flow Design for the meta-Selective C-H Arylation of Anilines.

PubMed

Gemoets, Hannes P L; Laudadio, Gabriele; Verstraete, Kirsten; Hessel, Volker; Noël, Timothy

2017-06-12

Described herein is an effective and practical modular flow design for the meta-selective C-H arylation of anilines. The design consists of four continuous-flow modules (i.e., diaryliodonium salt synthesis, meta-selective C-H arylation, inline copper extraction, and aniline deprotection) which can be operated either individually or consecutively to provide direct access to meta-arylated anilines. With a total residence time of 1 hour, the desired product could be obtained in high yield and excellent purity without the need for column chromatography, and the residual copper content meets the standards for parenterally administered pharmaceutical substances. © 2017 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

Distinct Effect of Benzalkonium Chloride on the Esterase and Aryl Acylamidase Activities of Butyrylcholinesterase.

PubMed

Jaganathan; Boopathy

2000-08-01

Acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) from vertebrates, other than their predominant acylcholine hydrolase (esterase) activity, display a genuine aryl acylamidase activity (AAA) capable of hydrolyzing the synthetic substrate o-nitroacetanilide to o-nitroaniline. This AAA activity is strongly inhibited by classical cholinesterase (ChE) inhibitors. In the present study, benzalkonium chloride (BAC), a cationic detergent widely used as a preservative in pharmaceutical preparations, has been shown to distinctly modulate the esterase and AAA activities of BChEs. The detergent BAC was able to inhibit the esterase activity of human serum and horse serum BChEs and AChEs from electric eel and human erythrocyte. The remarkable property of BAC was its ability to profoundly activate the AAA activity of human serum and horse serum BChEs but not the AAA activity of AChEs. Thus BAC seem to preferentially activate the AAA activity of BChEs alone. Results of the study using the ChE active site-specific inhibitor diisopropyl phosphorofluoridate indicated that BAC binds to the active site of ChEs. Furthermore, studies using a structural homolog of BAC indicated that the alkyl group of BAC is essential not only for its interaction with ChEs but also for its distinct effect on the esterase and AAA activities of BChEs. This is the first report of a compound that inhibits the esterase activity, while simultaneously activating the AAA activity, of BChEs. Copyright 2000 Academic Press.

Discovery of the aryl heterocyclic amine insecticides: synthesis, insecticidal activity, field results, mode of action and bioavailability of a leading field candidate.

PubMed

Dent, William H; Pobanz, Mark A; Geng, Chaoxian; Sparks, Thomas C; Watson, Gerald B; Letherer, Theodore J; Beavers, Kenneth W; Young, Cathy D; Adelfinskaya, Yelena A; Ross, Ronald R; Whiteker, Greg; Renga, James

2017-04-01

γ-Amino butyric acid (GABA) antagonists are proven targets for control of lepidopteran and other pests. New heterocyclic compounds with high insecticidal activity were discovered using a competitive-intelligence-inspired scaffold-hopping approach to generate analogs of fipronil, a known GABA antagonist. These novel aryl heterocyclic amines (AHAs) displayed broad-spectrum activity on a number of chewing insect pests. Through >370 modifications of the core AHA structure, a 7-pyrazolopyridine lead molecule was found to exhibit much improved activity on a number of insect pests. In field trial studies, its performance was 2-4 times lower than commercial standards and also appeared to be species dependent, with good activity seen for larvae of Spodoptera exigua, but inactivity on larvae of Trichoplusia ni. An extensive investigational biology effort demonstrated that these AHA analogs appear to have multiple modes of action, including GABA receptor antagonism and mitopotential or uncoupler activity. The limited capability in larvae of T. ni to convert the lead molecule to its associated open form correlates with the low toxicity of the lead molecule in this species. This work has provided information that could aid investigations of novel GABA antagonists. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

Decreased expression of the aryl hydrocarbon receptor in ocular Behcet's disease.

PubMed

Wang, Chaokui; Ye, Zi; Kijlstra, Aize; Zhou, Yan; Yang, Peizeng

2014-01-01

Recent studies show that the aryl hydrocarbon receptor (AhR) is involved in immune responses. AhR is activated following interaction with its ligands, such as 6-formylindolo[3,2-b]carbazole (FICZ) and 2-(1'H-indole-3'-carbonyl)-thiazole-4-carboxylic acid methyl ester (ITE). In this study, we investigated the role of AhR activation by its endogenous ligands in the pathogenesis of ocular Behcet's disease (BD). The expression of AhR was significantly decreased in active BD patients as compared to inactive BD patients and normal controls. Both FICZ and ITE inhibited Th1 and Th17 polarization and induced the expression of IL-22 by PBMCs and by CD4(+)T cells in active BD patients and normal controls. Stimulation of purified CD4(+)T cells with FICZ or ITE caused a decreased expression of RORC, IL-17, IL-23R, and CCR6 and an increased phosphorylation of STAT3 and STAT5. The present study suggests that a decreased AhR expression is associated with disease activity in BD patients. The activation of AhR by either FICZ or ITE was able to inhibit Th1 and Th17 cell polarization. Further studies are needed to investigate whether modulation of AhR might be used in the treatment of BD.

Superbanone, A New 2-Aryl-3-benzofuranone and Other Bioactive Constituents from the Tube Roots of Butea superba.

PubMed

Boonsombat, Jutatip; Prachyawarakorn, Vilailak; Pansanit, Acharavadee; Mahidol, Chulabhorn; Ruchirawat, Somsak; Thongnest, Sanit

2017-07-01

Phytochemical investigation from the tube roots of Butea superba, led to the isolation and identification of a new 2-aryl-3-benzofuranone named superbanone (1), one benzoin, 2-hydroxy-1-(2-hydroxy-4-methoxyphenyl)-2-(4-methoxyphenyl)ethanone (2), eight pterocarpans (3 - 10), and eleven isoflavonoids (11 - 21). Compound 2 was identified for the first time as a natural product. The structure of the isolated compounds was elucidated using spectroscopic methods, mainly 1D- and 2D-NMR. The isolated compounds and their derivatives were evaluated for α-glucosidase inhibitory and antimalarial activities. Compounds 3, 7, 8, and 11 showed promising α-glucosidase inhibitory activity (IC 50  = 13.71 ± 0.54, 23.54 ± 0.75, 28.83 ± 1.02, and 12.35 ± 0.36 μm, respectively). Compounds 3 and 11 were twofold less active than the standard drug acarbose (IC 50  = 6.54 ± 0.04 μm). None of the tested compounds was found to be active against Plasmodium falciparum strain 94. On the basis of biological activity results, structure-activity relationships are discussed. © 2017 Wiley-VHCA AG, Zurich, Switzerland.

Palladium-catalyzed one-pot three- or four-component coupling of aryl iodides, alkynes, and amines through C-N bond cleavage: efficient synthesis of indole derivatives.

PubMed

Hao, Wei; Geng, Weizhi; Zhang, Wen-Xiong; Xi, Zhenfeng

2014-02-24

An efficient synthesis of N-substituted indole derivatives was realized by combining the Pd-catalyzed one-pot multicomponent coupling approach with cleavage of the C(sp(3))-N bonds. Three or four components of aryl iodides, alkynes, and amines were involved in this coupling process. The cyclopentadiene-phosphine ligand showed high efficiency. A variety of aryl iodides, including cyclic and acyclic tertiary amino aryl iodides, and substituted 1-bromo-2-iodobenzene derivatives could be used. Both symmetric and unsymmetric alkynes substituted with alkyl, aryl, or trimethylsilyl groups could be applied. Cyclic secondary amines such as piperidine, morpholine, 4-methylpiperidine, 1-methylpiperazine, 2-methylpiperidine, and acyclic amines including secondary and primary amines all showed good reactivity. Further application of the resulting indole derivatives was demonstrated by the synthesis of benzosilolo[2,3-b]indole. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Genetic dissection of endothelial transcriptional activity of zebrafish aryl hydrocarbon receptors (AHRs).

PubMed

Sugden, Wade W; Leonardo-Mendonça, Roberto C; Acuña-Castroviejo, Darío; Siekmann, Arndt F

2017-01-01

The aryl hydrocarbon receptor (AHR) is a basic helix-loop-helix transcription factor conserved across phyla from flies to humans. Activated by a number of endogenous ligands and environmental toxins, studies on AHR function and gene regulation have largely focused on a toxicological perspective relating to aromatic hydrocarbons generated by human activities and the often-deleterious effects of exposure on vertebrates mediated by AHR activation. A growing body of work has highlighted the importance of AHR in physiologic processes, including immune cell differentiation and vascular patterning. Here we dissect the contribution of the 3 zebrafish AHRs, ahr1a, ahr1b and ahr2, to endothelial cyp1a1/b1 gene regulation under physiologic conditions and upon exposure to the AHR ligand Beta-naphthoflavone. We show that in fish multiple AHRs are functional in the vasculature, with vessel-specific differences in the ability of ahr1b to compensate for the loss of ahr2 to maintain AHR signaling. We further provide evidence that AHR can regulate the expression of the chemokine receptor cxcr4a in endothelial cells, a regulatory mechanism that may provide insight into AHR function in the endothelium.

New synthesis and antiparasitic activity of model 5-aryl-1-methyl-4-nitroimidazoles.

PubMed

Saadeh, Haythem A; Mosleh, Ibrahim M; El-Abadelah, Mustafa M

2009-07-27

A number of 5-aryl-1-methyl-4-nitroimidazoles 5a-f have been synthesized in good yields by the Suzuki coupling reaction between 5-chloro-1-methyl-4-nitroimidazole (3) and arylboronic acids 4a-f, aided by dichlorobis-(triphenylphosphine)palladium(II), K(2)CO(3, )and tetrabutylammonium bromide in water at 70-80 degrees C. Compounds 5a-f were characterized by elemental analysis, NMR and MS spectral data. On the basis of in vitro screening data, 5-(3-chlorophenyl)-1-methyl-4-nitro-1H-imidazole (5f) exhibited potent lethal activity against Entamoeba histolytica and Giardia intestinalis with IC(50) = 1.47 microM/mL, a value lower by a factor of two than that of the standard drug, metronidazole. The boosted activity of 5f was not accompanied by any increased cytotoxicity.The rest of the series also exhibited potent antiparasitic activity with IC(50 ) values in the 1.72-4.43 microM/mL range. The cytotoxicity of the derivatives 5c and 5e was increased compared to the precursor compound, metronidazole, although they remain non-cytotoxic at concentrations much higher than the antiparasitic concentration of the two derivatives.

Understanding the molecular mechanism of aryl acylamidase activity of acetylcholinesterase - An in silico study.

PubMed

Chinnadurai, Raj Kumar; Saravanaraman, Ponne; Boopathy, Rathanam

2015-08-15

Acetylcholinesterase (AChE) exhibits two different activities, namely esterase and aryl acylamidase (AAA). Unlike esterase, AAA activity of AChE is inhibited by the active site inhibitors while remaining unaffected by the peripheral anionic site inhibitors. This differential inhibitory pattern of active and peripheral anionic site inhibitors on the AAA activity remains unanswered. To answer this, we investigated the mechanism of binding and trafficking of AAA substrates using in silico tools. Molecular docking of serotonin and AAA substrates (o-nitroacetanilide, and o-nitrotrifluoroacetanilide,) onto AChE shows that these compounds bind at the side door of AChE. Thus, we conceived that the AAA substrates prefer the side door to reach the active site for their catalysis. Further, steered molecular dynamics simulations show that the force required for binding and trafficking of the AAA substrate through the side door is comparatively lesser than their dissociation (900kJ/mol/nm). Among the two substrates, o-nitrotrifluoroacetanilide required lesser force (380kJ/mol/nm) than o-nitroacetanilide the (550kJ/mol/nm) for its binding, thus validating o-nitrotrifluoroacetanilide as a better substrate. With these observations, we resolve that the AAA activity of AChE is mediated through its side door. Therefore, binding of PAS inhibitors at the main door of AChE remain ineffective against AAA activity. Copyright © 2015 Elsevier Inc. All rights reserved.

AhR and Arnt differentially regulate NF-κB signaling and chemokine responses in human bronchial epithelial cells

PubMed Central

2014-01-01

Background The aryl hydrocarbon receptor (AhR) has gradually emerged as a regulator of inflammation in the lung and other tissues. AhR may interact with the p65-subunit of the nuclear factor (NF)-κB transcription factors, but reported outcomes of AhR/NF-κB-interactions are conflicting. Some studies suggest that AhR possess pro-inflammatory activities while others suggest that AhR may be anti-inflammatory. The present study explored the impact of AhR and its binding partner AhR nuclear translocator (Arnt) on p65-activation and two differentially regulated chemokines, CXCL8 (IL-8) and CCL5 (RANTES), in human bronchial epithelial cells (BEAS-2B). Results Cells were exposed to CXCL8- and CCL5-inducing chemicals, 1-nitropyrene (1-NP) and 1-aminopyrene (1-AP) respectively, or the synthetic double-stranded RNA analogue, polyinosinic-polycytidylic acid (Poly I:C) which induced both chemokines. Only CXCL8, and not CCL5, appeared to be p65-dependent. Yet, constitutively active unligated AhR suppressed both CXCL8 and CCL5, as shown by siRNA knock-down and the AhR antagonist α-naphthoflavone. Moreover, AhR suppressed activation of p65 by TNF-α and Poly I:C as assessed by luciferase-assay and p65-phosphorylation at serine 536, without affecting basal p65-activity. In contrast, Arnt suppressed only CXCL8, but did not prevent the p65-activation directly. However, Arnt suppressed expression of the NF-κB-subunit RelB which is under transcriptional regulation by p65. Furthermore, AhR-ligands alone at high concentrations induced a moderate CXCL8-response, without affecting CCL5, but suppressed both CXCL8 and CCL5-responses by Poly I:C. Conclusion AhR and Arnt may differentially and independently regulate chemokine-responses induced by both inhaled pollutants and pulmonary infections. Constitutively active, unligated AhR suppressed the activation of p65, while Arnt may possibly interfere with the action of activated p65. Moreover, ligand-activated AhR suppressed CXCL8 and CCL5 responses by other agents, but AhR ligands alone induced CXCL8 responses when given at sufficiently high concentrations, thus underscoring the duality of AhR in regulation of inflammation. We propose that AhR-signaling may be a weak activator of p65-signaling that suppresses p65-activity induced by strong activators of NF-κB, but that its anti-inflammatory properties also are due to interference with additional pathways. PMID:25201625

Nickel-catalyzed amination of aryl chlorides with ammonia or ammonium salts.

PubMed

Green, Rebecca A; Hartwig, John F

2015-03-16

The nickel-catalyzed amination of aryl chlorides to form primary arylamines occurs with ammonia or ammonium sulfate and a well-defined single-component nickel(0) precatalyst containing a Josiphos ligand and an η(2)-bound benzonitrile ligand. This system also catalyzes the coupling of aryl chlorides with gaseous amines in the form of their hydrochloride salts. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Direct Synthesis of 5-Aryl Barbituric Acids by Rhodium(II)-Catalyzed Reactions of Arenes with Diazo Compounds**

PubMed Central

Best, Daniel; Burns, David J; Lam, Hon Wai

2015-01-01

A commercially available rhodium(II) complex catalyzes the direct arylation of 5-diazobarbituric acids with arenes, allowing straightforward access to 5-aryl barbituric acids. Free N—H groups are tolerated on the barbituric acid, with no complications arising from N—H insertion processes. This method was applied to the concise synthesis of a potent matrix metalloproteinase (MMP) inhibitor. PMID:25959544

A beta-keto ester as a novel, efficient, and versatile ligand for copper(I)-catalyzed C-N, C-O, and C-S coupling reactions.

PubMed

Lv, Xin; Bao, Weiliang

2007-05-11

Employing ethyl 2-oxocyclohexanecarboxylate as a novel, efficient, and versatile ligand, the copper-catalyzed coupling reactions of various N/O/S nucleophilic reagents with aryl halides could be successfully carried out under mild conditions. A variety of products including N-arylamides, N-arylimidazoles, aryl ethers, and aryl thioethers were synthesized in good to excellent yields.

Towards a fragment-based approach in gelator design: halogen effects leading to thixotropic, mouldable and self-healing systems in aryl-triazolyl amino acid-based gelators!

PubMed

Srivastava, Bhartendu K; Manheri, Muraleedharan K

2017-04-18

A simple replacement of a H atom by Br transformed non-gelating aryl triazolyl amino acid benzyl ester into a versatile gelator, which formed shape-persistent, self-healing and mouldable gels. The 'bromo-aryl benzyl ester' fragment was then transplanted into another framework, which resulted in similar solvent preference and gelation efficiency.

Use of Aryl Chlorides as Electrophiles in Pd-Catalyzed Alkene Difunctionalization Reactions

PubMed Central

Rosen, Brandon R.; Ney, Joshua E.; Wolfe, John P.

2010-01-01

The development of conditions that allow use of inexpensive aryl chlorides as electrophiles in Pd-catalyzed alkene carboamination and carboetherification reactions is described. A catalyst composed of Pd(OAc)2 and S-Phos minimizes N-arylation of the substrate and prevents formation of mixtures of regioisomeric products. A number of heterocycles, including pyrrolidines, isoxazolidines, tetrahydrofurans, and pyrazolidines, are efficiently generated with this method. PMID:20297834

Synthesis Of [2h, 13c]M [2h2m 13c], And [2h3,, 13c] Methyl Aryl Sulfones And Sulfoxides

DOEpatents

Martinez, Rodolfo A.; Alvarez, Marc A.; Silks, III, Louis A.; Unkefer, Clifford J.; Schmidt, Jurgen G.

2004-07-20

The present invention is directed to labeled compounds, [.sup.2 H.sub.1, .sup.13 C], [.sup.2 H.sub.2, .sup.13 C] and [.sup.2 H.sub.3, .sup.13 C]methyl aryl sulfones and [.sup.2 H.sub.1, .sup.13 C], [.sup.2 H.sub.2, .sup.13 C] and [.sup.2 H.sub.3, .sup.13 C]methyl aryl sulfoxides, wherein the .sup.13 C methyl group attached to the sulfur of the sulfone or sulfoxide includes exactly one, two or three deuterium atoms and the aryl group is selected from the group consisting of 1-naphthyl, substituted 1-naphthyl, 2-naphthyl, substituted 2-naphthyl, and phenyl groups with the structure: ##STR1## wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4 and R.sub.5 are each independently, hydrogen, a C.sub.1 -C.sub.4 lower alkyl, a halogen, an amino group from the group consisting of NH.sub.2, NHR and NRR' where R and R' are each a C.sub.1 -C.sub.4 lower alkyl, a phenyl, or an alkoxy group. The present invention is also directed to processes of preparing methyl aryl sulfones and methyl aryl sulfoxides.

Prevention of melanin formation during aryl alcohol oxidase production under growth-limited conditions using an Aspergillus nidulans cell factory.

PubMed

Pardo-Planas, Oscar; Prade, Rolf A; Müller, Michael; Atiyeh, Hasan K; Wilkins, Mark R

2017-11-01

An Aspergillus nidulans cell factory was genetically engineered to produce an aryl alcohol oxidase (AAO). The cell factory initiated production of melanin when growth-limited conditions were established using stationary plates and shaken flasks. This phenomenon was more pronounced when the strain was cultured in a trickle bed reactor (TBR). This study investigated different approaches to reduce melanin formation in fungal mycelia and liquid medium in order to increase the enzyme production yield. Removal of copper from the medium recipe reduced melanin formation in agar cultures and increased enzyme activities by 48% in agitated liquid cultures. Copper has been reported as a key element for tyrosinase, an enzyme responsible for melanin production. Ascorbic acid (0.44g/L) stopped melanin accumulation, did not affect growth parameters and resulted in AAO activity that was more than two-fold greater than a control treatment with no ascorbic acid. Copyright © 2017 Elsevier Ltd. All rights reserved.

A Microplate Format Assay for Real-Time Screening for New Aldolases that Accept Aryl-Substituted Acceptor Substrates.

PubMed

Ma, Huan; Enugala, Thilak Reddy; Widersten, Mikael

2015-12-01

Aldolases are potentially important biocatalysts for asymmetric synthesis of polyhydroxylated compounds. Fructose 6-phosphate aldolase (FSA) is of particular interest by virtue of its unusually relaxed dependency on phosphorylated substrates. FSA has been reported to be a promising catalyst of aldol addition involving aryl-substituted acceptors such as phenylacetaldehyde that can react with donor ketones such as hydroxyacetone. Improvement of the low intrinsic activity with bulky acceptor substrates of this type is of great interest but has been hampered by the lack of powerful screening protocols applicable in directed evolution strategies. Here we present a new screen allowing for direct spectrophotometric recording of retro-aldol cleavage. The assay utilizes an aldehyde reductase produced in vitro by directed evolution; it reduces the aldehyde product formed after cleavage of the aldol by FSA. The assay is suitable both for steady-state enzyme kinetics and for real-time activity screening in a 96-well format. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Protein dynamics promote hydride tunnelling in substrate oxidation by aryl-alcohol oxidase.

PubMed

Carro, Juan; Martínez-Júlvez, Marta; Medina, Milagros; Martínez, Angel T; Ferreira, Patricia

2017-11-01

The temperature dependence of hydride transfer from the substrate to the N5 of the FAD cofactor during the reductive half-reaction of Pleurotus eryngii aryl-alcohol oxidase (AAO) is assessed here. Kinetic isotope effects on both the pre-steady state reduction of the enzyme and its steady-state kinetics, with differently deuterated substrates, suggest an environmentally-coupled quantum-mechanical tunnelling process. Moreover, those kinetic data, along with the crystallographic structure of the enzyme in complex with a substrate analogue, indicate that AAO shows a pre-organized active site that would only require the approaching of the hydride donor and acceptor for the tunnelled transfer to take place. Modification of the enzyme's active-site architecture by replacement of Tyr92, a residue establishing hydrophobic interactions with the substrate analogue in the crystal structure, in the Y92F, Y92L and Y92W variants resulted in different temperature dependence patterns that indicated a role of this residue in modulating the transfer reaction.

The Aryl Hydrocarbon Receptor (AhR) as a Drug Target for Cancer Chemotherapy.

PubMed

Safe, Stephen; Cheng, Yating; Jin, Un-Ho

2017-02-01

The aryl hydrocarbon receptor (AhR) is overexpressed in some patients with different tumor types, and the receptor can be a negative or positive prognostic factor. There is also evidence from both in vivo and in vitro cell culture models that the AhR can exhibit tumor-specific pro-oncogenic and tumor suppressor-like functions and therefore can be treated with AhR antagonists or agonists, respectively. Successful clinical applications of AhR ligands will require the synthesis and development of selective AhR modulators (SAhRMs) with tumor-specific AhR agonist or antagonist activity, and some currently available compounds such as indole-3-carbinol and diindolylmethane-(DIM) and synthetic AhR antagonists are potential drug candidates. There is also evidence that some AhR-active pharmaceuticals, including tranilast, flutamide, hydroxytamoxifen and omeprazole or their derivatives, may be effective AhR-dependent anticancer agents for single or combination cancer chemotherapies for treatment of breast and pancreatic cancers.

Aryl hydrocarbon receptor (AhR) a possible target for the treatment of skin disease.

PubMed

Napolitano, Maddalena; Patruno, Cataldo

2018-07-01

Aryl hydrocarbon receptor (AhR) is a transcription factor expressed in all skin cells type. It responds to exogenous and endogenous chemicals by inducing/repressing the expression of several genes with toxic or protective effects in a wide range of species and tissues. In healthy skin, AhR signalling contributes to keratinocytes differentiation, skin barrier function, skin pigmentation, and mediates oxidative stress. In the last years, some studies have shown that AhR seems to be involved in the pathogenesis of some skin diseases, even if the currently available data are contradictory. Indeed, while the blocking the AhR signalling activity could prevent or treat skin cancer, the AhR activation seems to be advantageous for the treatment of inflammatory skin diseases. Therefore, for its multifaceted role in skin diseases, AhR seems to be an attractive therapeutic target. Indeed, recently some molecules have been identified for the prevention of skin cancer and the treatment of inflammatory skin diseases. Copyright © 2018 Elsevier Ltd. All rights reserved.

Dioxin Toxicity In Vivo Results from an Increase in the Dioxin-Independent Transcriptional Activity of the Aryl Hydrocarbon Receptor

PubMed Central

Céspedes, Miguel Angel; Galindo, Maximo Ibo; Couso, Juan Pablo

2010-01-01

The Aryl hydrocarbon receptor (Ahr) is the nuclear receptor mediating the toxicity of dioxins -widespread and persistent pollutants whose toxic effects include tumor promotion, teratogenesis, wasting syndrome and chloracne. Elimination of Ahr in mice eliminates dioxin toxicity but also produces adverse effects, some seemingly unrelated to dioxin. Thus the relationship between the toxic and dioxin-independent functions of Ahr is not clear, which hampers understanding and treatment of dioxin toxicity. Here we develop a Drosophila model to show that dioxin actually increases the in vivo dioxin-independent activity of Ahr. This hyperactivation resembles the effects caused by an increase in the amount of its dimerisation partner Ahr nuclear translocator (Arnt) and entails an increased transcriptional potency of Ahr, in addition to the previously described effect on nuclear translocation. Thus the two apparently different functions of Ahr, dioxin-mediated and dioxin-independent, are in fact two different levels (hyperactivated and basal, respectively) of a single function. PMID:21079739

Aryl hydrocarbon receptor and intestinal immunity.

PubMed

Lamas, Bruno; Natividad, Jane M; Sokol, Harry

2018-04-07

Aryl hydrocarbon receptor (AhR) is a member of the basic helix-loop-helix-(bHLH) superfamily of transcription factors, which are associated with cellular responses to environmental stimuli, such as xenobiotics and oxygen levels. Unlike other members of bHLH, AhR is the only bHLH transcription factor that is known to be ligand activated. Early AhR studies focused on understanding the role of AhR in mediating the toxicity and carcinogenesis properties of the prototypic ligand 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). In recent years, however, it has become apparent that, in addition to its toxicological involvement, AhR is highly receptive to a wide array of endogenous and exogenous ligands, and that its activation leads to a myriad of key host physiological functions. In this study, we review the current understanding of the functions of AhR in the mucosal immune system with a focus on its role in intestinal barrier function and intestinal immune cells, as well as in intestinal homeostasis.

A comparative study of two novel unsymmetrically substituted triazacyclohexanes

NASA Astrophysics Data System (ADS)

Lamraoui, Hanane; Messai, Amel; Bilge, Duygu; Bilge, Metin; Bouchemma, Ahcen; Parlak, Cemal

2017-06-01

Novel unsymmetrically N-substituted N,N‧-R1N″-R2-1,3,5-triazacyclohexanes (1b and 2b; R1 = p-chlorophenyl or p-methoxyphenyl and R2 = butyl or cyclohexyl) have been synthesized in a good yield from condensation reaction by excess amine. Both triazacyclohexane rings have chair conformation. However, 1b adopts diaxial orientation of aryl groups and an equatorial form of alkyl group whereas 2b prefers an axial orientation of the alkyl group and diequatorial forms of aryl groups. 1b is consolidated by weak C-H⋯π interactions. Intra-molecular C-H⋯O or C-H⋯N hydrogen bonds and C-H⋯π may be effective in the stabilization of 2b. Both compounds have showed moderate antimicrobial activity, but 1b exhibits higher activity than 2b. All experimental results are found in good support to theoretical data. Findings of research may be helpful guide for the medicinal chemists and the field is further open for pharmacokinetics studies.

UDP-Glucuronosyltransferase Expression in Mouse Liver Is Increased in Obesity- and Fasting-Induced Steatosis

PubMed Central

Xu, Jialin; Kulkarni, Supriya R.; Li, Liya

2012-01-01

UDP-glucuronosyltransferases (Ugt) catalyze phase II conjugation reactions with glucuronic acid, which enhances chemical polarity and the elimination from the body. Few studies have addressed whether Ugt expression and activity are affected by liver disease, such as steatosis. The purpose of this study was to determine whether steatosis induced by obesity or fasting could affect liver Ugt mRNA expression and activity. Male C57BL/6J and Lepob/ob (ob/ob) mice were fed ad libitum or food was withheld for 24 h. In steatotic livers of ob/ob mice, Ugt1a1, -1a6, -1a9, -2a3, -3a1, and -3a2 mRNA expression increased. Fasting, which also induced steatosis, increased hepatic Ugt1a1, -1a6, -1a7, -1a9, -2b1, -2b5, -2a3, -3a1, and -3a2 mRNA expression in mouse liver. Likewise, acetaminophen glucuronidation increased by 47% in hepatic microsomes from ob/ob mice compared with that in C57BL/6J mice, but not after fasting. In both steatosis models, Ugt induction was accompanied by increased aryl hydrocarbon receptor, constitutive androstane receptor (CAR), peroxisome proliferator-activated receptor (PPAR)-α, pregnane X receptor, nuclear factor (erythroid-derived 2)-like 2 (Nrf2), and peroxisome proliferator-activated receptor-γ coactivator-1α mRNA expression. In addition, fasting increased CAR, PPAR, and Nrf2 binding activity. The work points to hepatic triglyceride concentrations corresponding with nuclear receptor and Ugt expression. The findings indicate that steatosis significantly alters hepatic Ugt expression and activity, which could have a significant impact on determining circulating hormone levels, drug efficacy, and environmental chemical clearance. PMID:22031624

UDP-glucuronosyltransferase expression in mouse liver is increased in obesity- and fasting-induced steatosis.

PubMed

Xu, Jialin; Kulkarni, Supriya R; Li, Liya; Slitt, Angela L

2012-02-01

UDP-glucuronosyltransferases (Ugt) catalyze phase II conjugation reactions with glucuronic acid, which enhances chemical polarity and the elimination from the body. Few studies have addressed whether Ugt expression and activity are affected by liver disease, such as steatosis. The purpose of this study was to determine whether steatosis induced by obesity or fasting could affect liver Ugt mRNA expression and activity. Male C57BL/6J and Lep(ob/ob) (ob/ob) mice were fed ad libitum or food was withheld for 24 h. In steatotic livers of ob/ob mice, Ugt1a1, -1a6, -1a9, -2a3, -3a1, and -3a2 mRNA expression increased. Fasting, which also induced steatosis, increased hepatic Ugt1a1, -1a6, -1a7, -1a9, -2b1, -2b5, -2a3, -3a1, and -3a2 mRNA expression in mouse liver. Likewise, acetaminophen glucuronidation increased by 47% in hepatic microsomes from ob/ob mice compared with that in C57BL/6J mice, but not after fasting. In both steatosis models, Ugt induction was accompanied by increased aryl hydrocarbon receptor, constitutive androstane receptor (CAR), peroxisome proliferator-activated receptor (PPAR)-α, pregnane X receptor, nuclear factor (erythroid-derived 2)-like 2 (Nrf2), and peroxisome proliferator-activated receptor-γ coactivator-1α mRNA expression. In addition, fasting increased CAR, PPAR, and Nrf2 binding activity. The work points to hepatic triglyceride concentrations corresponding with nuclear receptor and Ugt expression. The findings indicate that steatosis significantly alters hepatic Ugt expression and activity, which could have a significant impact on determining circulating hormone levels, drug efficacy, and environmental chemical clearance.

Stimulation of aryl metabolite production in the basidiomycete Bjerkandera sp. strain BOS55 with biosynthetic precursors and lignin degradation products.

PubMed Central

Mester, T; Swarts, H J; Romero i Sole, S; de Bont, J A; Field, J A

1997-01-01

Aryl metabolites are known to have an important role in the ligninolytic system of white rot fungi. The addition of known precursors and aromatic acids representing lignin degradation products stimulated the production of aryl metabolites (veratryl alcohol, veratraldehyde, p-anisaldehyde, and 3-chloro-p-anisaldehyde) in the white rot fungus Bjerkandera sp. strain BOS55. The presence of manganese (Mn) is known to inhibit the biosynthesis of veratryl alcohol (T. Mester, E. de Jong, and J.A. Field, Appl. Environ. Microbiol. 61:1881-1887, 1995). A new finding of this study was that the production of the other aryl metabolites, p-anisaldehyde and 3-chloro-p-anisaldehyde, was also inhibited by Mn. We attempted to bypass the Mn-inhibited step in the biosynthesis of aryl metabolites by the addition of known and suspected precursors. Most of these compounds were not able to bypass the inhibiting effect of Mn. Only the fully methylated precursors (veratrate, p-anisate, and 3-chloro-p-anisate) provided similar concentrations of aryl metabolites in the presence and absence of Mn, indicating that Mn does not influence the reduction of the benzylic acid group. The addition of deuterated benzoate and 4-hydroxybenzoate resulted in the formation of deuterated aryl metabolites, indicating that these aromatic acids entered into the biosynthetic pathway and were common intermediates to all aryl metabolites. Only deuterated chlorinated anisyl metabolites were produced when the cultures were supplemented with deuterated 3-chloro-4-hydroxybenzoate. This observation combined with the fact that 3-chloro-4-hydroxybenzoate is a natural product of Bjerkandera spp. (H. J. Swarts, F. J. M. Verhagen, J. A. Field, and J. B. P. A. Wijnberg, Phytochemistry 42:1699-1701, 1996) suggest that it is a possible intermediate in chlorinated anisyl metabolite biosynthesis. PMID:9143129

The aryl hydrocarbon receptor is required for the maintenance of liver-resident natural killer cells

PubMed Central

2016-01-01

A tissue-resident population of natural killer cells (NK cells) in the liver has recently been described to have the unique capacity to confer immunological memory in the form of hapten-specific contact hypersensitivity independent of T and B cells. Factors regulating the development and maintenance of these liver-resident NK cells are poorly understood. The aryl hydrocarbon receptor (AhR) is a transcription factor modulated by exogenous and endogenous ligands that is important in the homeostasis of immune cells at barrier sites, such as the skin and gut. In this study, we show that liver-resident NK (NK1.1+CD3−) cells, defined as CD49a+TRAIL+CXCR6+DX5− cells in the mouse liver, constitutively express AhR. In AhR−/− mice, there is a significant reduction in the proportion and absolute number of these cells, which results from a cell-intrinsic dependence on AhR. This deficiency in liver-resident NK cells appears to be the result of higher turnover and increased susceptibility to cytokine-induced cell death. Finally, we show that this deficiency has functional implications in vivo. Upon hapten exposure, AhR−/− mice are not able to mount an NK cell memory response to hapten rechallenge. Together, these data demonstrate the requirement of AhR for the maintenance of CD49a+TRAIL+CXCR6+DX5− liver-resident NK cells and their hapten memory function. PMID:27670593

Purification and properties of aryl acylamidase from Pseudomonas fluorescens ATCC 39004.

PubMed

Hammond, P M; Price, C P; Scawen, M D

1983-05-16

Aryl acylamidase has been purified from a strain of Pseudomonas fluorescens ATCC 39004, selected from soil on the basis of its ability to utilise acylanilide compounds as a sole source of carbon. The enzyme was purified to homogeneity by a combination of ion-exchange, hydrophobic and gel-permeation chromatography. A relative molecular mass of about 52 500 was estimated by gel filtration. The native enzyme was shown to be a monomeric protein by sodium dodecyl sulphate/polyacrylamide gel electrophoresis. The enzyme was maximally active at a pH of 8.6 and at a temperature of 45 degrees C. The enzyme shows Michaelis-Menten kinetics; Km values for nitroacetanilide (69 microM) and hydroxyacetanilide (6.1 microM) were low, indicating that the enzyme has a very high affinity for both substrates.

An endogenous aryl hydrocarbon receptor ligand inhibits proliferation and migration of human ovarian cancer cells.

PubMed

Wang, Kai; Li, Yan; Jiang, Yi-Zhou; Dai, Cai-Feng; Patankar, Manish S; Song, Jia-Sheng; Zheng, Jing

2013-10-28

The aryl hydrocarbon receptor (AhR), a ligand-activated transcription factor mediates many biological processes. Herein, we investigated if 2-(1'H-indole-3'-carbonyl)-thiazole-4-carboxylic acid methyl ester (ITE, an endogenous AhR ligand) regulated proliferation and migration of human ovarian cancer cells via AhR. We found that AhR was widely present in many histotypes of ovarian cancer tissues. ITE suppressed OVCAR-3 cell proliferation and SKOV-3 cell migration in vitro, which were blocked by AhR knockdown. ITE also suppressed OVCAR-3 cell growth in mice. These data suggest that the ITE might potentially be used for therapeutic intervention for at least a subset of human ovarian cancer. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Aryl-1H-imidazole[4,5f][1,10]phenanthroline Cu(II) complexes: Electrochemical and DNA interaction studies.

PubMed

Rajebhosale, Bharati S; Dongre, Shivali N; Deshpande, Sameer S; Kate, Anup N; Kumbhar, Anupa A

2017-10-01

The reaction of aryl imidazo[4,5f] [1,10]phenanthrolines with Cu(NO 3 ) 2 lead to the formation of Cu(II) complexes of the type [Cu(L)(NO 3 ) 2 ] where L=PIP, 2-(phenyl) [4,5f] imidazo phenanthroline; HPIP=2-(2-hydroxyphenyl)imidazo [4,5f] phenanthroline and NIP=2-(naphthyl) [4,5f] imidazo phenanthroline. The interaction of these complexes with calf thymus DNA has been studied using viscosity measurements, UV-visible and fluorescence spectroscopy. Chemical nuclease activity of these complexes has also been investigated. All complexes cleave DNA via oxidative pathway involving singlet oxygen. Molecular docking studies revealed that these complexes bind to DNA through minor groove. Copyright © 2017 Elsevier Inc. All rights reserved.

Combination of Aryl Diselenides/Hydrogen Peroxide and Carbon Nanotube-Rhodium Nanohybrid for Naphthols Oxidation: An Efficient Route towards Trypanocidal Quinones.

PubMed

de Carvalho, Renato L; Jardim, Guilherme A M; Santos, Augusto; Araujo, Maria H; Oliveira, Willian X C; Bombaça, Ana Cristina; Menna-Barreto, Rubem F S; Gopi, Elumalai; Gravel, Edmond; Doris, Eric; da Silva Júnior, Eufrânio Nunes

2018-06-14

We report a combination of aryl diselenides/hydrogen peroxide and carbon nanotube-rhodium nanohybrid for naphthols oxidation towards synthesis of 1,4-naphthoquinones and evaluation of their relevant trypanocidal activity. Under a combination of (PhSe)2/H2O2 in the presence of O2 in i-PrOH/Hexane, several benzenoid (A-ring) substituted quinones were prepared in moderate to high yields. We also studied the contribution of RhCNT as co-catalyst in this process and, in some cases, yields were improved. This method provides an efficient and versatile alternative for preparing A-ring modified naphthoquinonoid compounds with relevant biological profile. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Transnitrilation from Dimethylmalononitrile to Aryl Grignard and Lithium Reagents: A Practical Method for Aryl Nitrile Synthesis.

PubMed

Reeves, Jonathan T; Malapit, Christian A; Buono, Frederic G; Sidhu, Kanwar P; Marsini, Maurice A; Sader, C Avery; Fandrick, Keith R; Busacca, Carl A; Senanayake, Chris H

2015-07-29

An electrophilic cyanation of aryl Grignard or lithium reagents, generated in situ from the corresponding aryl bromides or iodides, by a transnitrilation with dimethylmalononitrile (DMMN) was developed. DMMN is a commercially available, bench-stable solid. The transnitrilation with DMMN avoids the use of toxic reagents and transition metals and occurs under mild reaction conditions, even for extremely sterically hindered substrates. The transnitrilation of aryllithium species generated by directed ortho-lithiation enabled a net C-H cyanation. The intermediacy of a Thorpe-type imine adduct in the reaction was supported by isolation of the corresponding ketone from the quenched reaction. Computational studies supported the energetic favorability of retro-Thorpe fragmentation of the imine adduct.

Lanthanum tricyanide-catalyzed acyl silane-ketone benzoin additions and kinetic resolution of resultant alpha-silyloxyketones.

PubMed

Tarr, James C; Johnson, Jeffrey S

2010-05-21

We report the full account of our efforts on the lanthanum tricyanide-catalyzed acyl silane-ketone benzoin reaction. The reaction exhibits a wide scope in both acyl silane (aryl, alkyl) and ketone (aryl-alkyl, alkyl-alkyl, aryl-aryl, alkenyl-alkyl, alkynyl-alkyl) coupling partners. The diastereoselectivity of the reaction has been examined in both cyclic and acyclic systems. Cyclohexanones give products arising from equatorial attack by the acyl silane. The diastereoselectivity of acyl silane addition to acyclic alpha-hydroxy ketones can be controlled by varying the protecting group to obtain either Felkin-Ahn or chelation control. The resultant alpha-silyloxyketone products can be resolved with selectivity factors from 10 to 15 by subjecting racemic ketone benzoin products to CBS reduction.

Rhodium(III)-catalyzed [3+2] annulation of 5-aryl-2,3-dihydro-1H-pyrroles with internal alkynes through C(sp²)-H/alkene functionalization.

PubMed

Zhou, Ming-Bo; Pi, Rui; Hu, Ming; Yang, Yuan; Song, Ren-Jie; Xia, Yuanzhi; Li, Jin-Heng

2014-10-13

This study describes a new rhodium(III)-catalyzed [3+2] annulation of 5-aryl-2,3-dihydro-1H-pyrroles with internal alkynes using a Cu(OAc)2 oxidant for building a spirocyclic ring system, which includes the functionalization of an aryl C(sp(2))-H bond and addition/protonolysis of an alkene C=C bond. This method is applicable to a wide range of 5-aryl-2,3-dihydro-1H-pyrroles and internal alkynes, and results in the assembly of the spiro[indene-1,2'-pyrrolidine] architectures in good yields with excellent regioselectivities. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Enhanced interfacial properties of carbon fiber composites via aryl diazonium reaction “on water”

NASA Astrophysics Data System (ADS)

Wang, Yuwei; Meng, Linghui; Fan, Liquan; Ma, Lichun; Qi, Meiwei; Yu, Jiali; Huang, Yudong

2014-10-01

Polyacrylonitrile-based carbon fibers were functionalized with phenyl amine group via aryl diazonium reaction "on water" to improve their interfacial bonding with resin matrix. Raman spectroscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and scanning electron microscopy were employed to characterize ordered degree, functional groups, chemical states and morphology of carbon fiber surface, respectively. The results showed that phenyl amine groups were grafted on the fiber surface successfully. Mechanical property test results indicated that the aryl diazonium reaction in this paper could improve the interfacial shear strength by 73%, while the tensile strength was down very slightly. Hence aryl diazonium reaction "on water" could be a facile green platform to functionalize carbon fibers for many interesting applications.

Synthesis of structurally diverse benzosuberene analogues and their biological evaluation as anti-cancer agents

PubMed Central

Tanpure, Rajendra P.; George, Clinton S.; Strecker, Tracy E.; Devkota, Laxman; Tidmore, Justin K.; Lin, Chen-Ming; Herdman, Christine A.; MacDonough, Matthew T.; Sriram, Madhavi; Chaplin, David J.; Trawick, Mary Lynn; Pinney, Kevin G.

2014-01-01

Diversely functionalized, fused aryl-alkyl ring systems hold a prominent position as well-established molecular frameworks for a variety of anti-cancer agents. The benzosuberene (6,7 fused, also referred to as dihydro-5H-benzo[7]annulene and benzocycloheptene) ring system has emerged as a valuable molecular core component for the development of inhibitors of tubulin assembly, which function as antiproliferative anti-cancer agents and, in certain cases, as vascular disrupting agents (VDAs). Both a phenolic-based analogue (known as KGP18, compound 39) and its corresponding amine-based congener (referred to as KGP156, compound 45), which demonstrate strong inhibition of tubulin assembly (low micromolar range) and potent cytotoxicity (picomolar range for KGP18 and nanomolar range for KGP156) are noteworthy examples of such benzosuberene-based compounds. In order to extend the structure-activity relationship (SAR) knowledge base related to benzosuberene anti-cancer agents, a series of eleven analogues (including KGP18) were prepared in which the methoxylation pattern on the pendant aryl ring as well as functional group incorporation on the fused aryl ring were varied. The synthetic approach to these compounds featured a sequential Wittig olefination, reduction, Eaton's reagent-mediated cyclization strategy to achieve the core benzosuberone intermediate, and represented a higher-yielding synthesis of KGP18 (which we prepared previously through a ring-expansion strategy). Incorporation of a fluorine or chlorine atom at the 1-position of the fused aryl ring or replacement of one of the methoxy groups with hydrogen (on the pendant aryl ring of KGP18) led to benzosuberene analogues that were both strongly inhibitory against tubulin assembly (IC50 approximately 1.0 M) and strongly cytotoxic against selected human cancer cell lines (for example, GI50 = 5.47 nM against NCI-H460 cells with fluorobenzosuberene analogue 37). A water-soluble phosphate prodrug salt of KGP18 (referred to as KGP265, compound 44) and a water-soluble serinamide salt (compound 48) of KGP156 were also synthesized and evaluated in this study. PMID:24183586

Design, synthesis, and protein crystallography of biaryltriazoles as potent tautomerase inhibitors of macrophage migration inhibitory factor.

PubMed

Dziedzic, Pawel; Cisneros, José A; Robertson, Michael J; Hare, Alissa A; Danford, Nadia E; Baxter, Richard H G; Jorgensen, William L

2015-03-04

Optimization is reported for biaryltriazoles as inhibitors of the tautomerase activity of human macrophage migration inhibitory factor (MIF), a proinflammatory cytokine associated with numerous inflammatory diseases and cancer. A combined approach was taken featuring organic synthesis, enzymatic assaying, crystallography, and modeling including free-energy perturbation (FEP) calculations. X-ray crystal structures for 3a and 3b bound to MIF are reported and provided a basis for the modeling efforts. The accommodation of the inhibitors in the binding site is striking with multiple hydrogen bonds and aryl-aryl interactions. Additional modeling encouraged pursuit of 5-phenoxyquinolinyl analogues, which led to the very potent compound 3s. Activity was further enhanced by addition of a fluorine atom adjacent to the phenolic hydroxyl group as in 3w, 3z, 3aa, and 3bb to strengthen a key hydrogen bond. It is also shown that physical properties of the compounds can be modulated by variation of solvent-exposed substituents. Several of the compounds are likely the most potent known MIF tautomerase inhibitors; the most active ones are more than 1000-fold more active than the well-studied (R)-ISO-1 and more than 200-fold more active than the chromen-4-one Orita-13.

Effects of human blood levels of two PAH mixtures on the AHR signalling activation pathway and CYP1A1 and COMT target genes in granulosa non-tumor and granulosa tumor cell lines.

PubMed

Zajda, Karolina; Ptak, Anna; Rak, Agnieszka; Fiedor, Elżbieta; Grochowalski, Adam; Milewicz, Tomasz; Gregoraszczuk, Ewa L

2017-08-15

Epidemiological studies have shown a link between problems with offspring of couples living in a contaminated environment in comparison to those who live in an uncontaminated environment. We measured the concentrations of 16 priority polycyclic aromatic hydrocarbons (PAHs) in maternal and cord blood. To explore the mechanism of the effects of PAH mixtures on nonluteinized granulosa cells (HGrC1) and granulosa tumor cells (COV434), as well as cell proliferation and apoptosis, we investigated the effect of PAH mixtures on the expression of the aryl hydrocarbon receptor (AHR), aryl hydrocarbon receptor nuclear translocator (ARNT) and aryl hydrocarbon receptor repressor (AHRR) genes, as well as the expression and activity of target genes cytochrome P450 1A1 (CYP1A1) and catechol-O-methyltransferase (COMT). The cells were exposed to mixture 1 (M1), composed of all 16 priority PAHs, and mixture 2 (M2), composed of five PAHs which are not classified as human carcinogens, and which are observed in the highest amounts both in maternal and cord blood. All 16 priority PAHs were bioavailable in maternal and cord plasma, suggesting that perinatal exposure should be considered. In HGrC1 cells, M1 increased AHR and ARNT, but decreased AHRR expression, in parallel with increased CYP1A1 and COMT expression and activity. M2 decreased AHR and AHRR, and increased ARNT, with no effect on CYP1A1 expression and activity; however, it did increase COMT expression and activity. In tumor cells, M1 lowered AHR and up-regulated AHRR and ARNT expression, consequently decreasing CYP1A1 expression and COMT activity. M2 up-regulated AHR and ARNT, down-regulated AHRR, and had no effect on CYP1A1 and COMT expression, but decreased COMT activity. We hypothesise that, dependent on composition, mixtures of PAHs activate the AHR differently through varying transcription responses: in HGrC1, a canonical AHR mechanism of M1, with activation of CYP1A1 important for detoxication, while in COV434, a noncanonical AHR mechanism, probably by activation the nuclear factor NFkB. Copyright © 2017. Published by Elsevier B.V.

Structure of aryl O -demethylase offers molecular insight into a catalytic tyrosine-dependent mechanism

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

Kohler, Amanda C.; Mills, Matthew J. L.; Adams, Paul D.

Some strains of soil and marine bacteria have evolved intricate metabolic pathways for using environmentally derived aromatics as a carbon source. Many of these metabolic pathways go through intermediates such as vanillate, 3-O-methylgallate, and syringate. Demethylation of these compounds is essential for downstream aryl modification, ring opening, and subsequent assimilation of these compounds into the tricarboxylic acid (TCA) cycle, and, correspondingly, there are a variety of associated aryl demethylase systems that vary in complexity. Intriguingly, only a basic understanding of the least complex system, the tetrahydrofolate-dependent aryl demethylase LigM from Sphingomonas paucimobilis, a bacterial strain that metabolizes lignin-derived aromatics, wasmore » previously available. LigM-catalyzed demethylation enables further modification and rin g opening of the single-ring aromatics vanillate and 3-Omethylgallate, which are common byproducts of biofuel production. We characterize aryl O-demethylation by LigM and report its 1.81-Å crystal structure, revealing a unique demethylase fold and a canonical folate-binding domain. Structural homology and geometry optimization calculations enabled the identification of LigM's tetrahydrofolate-binding site and protein-folate interactions. Computationally guided mutagenesis and kinetic analyses allowed the identification of the enzyme's aryl-binding site location and determination of its unique, catalytic tyrosine-dependent reaction mechanism. This work defines LigM as a distinct demethylase, both structurally and functionally, and provides insight into demethylation and its reaction requirements. Our results afford the mechanistic details required for efficient utilization of LigM as a tool for aryl O-demethylation and as a component of synthetic biology efforts to valorize previously underused aromatic compounds.« less

Structure of aryl O -demethylase offers molecular insight into a catalytic tyrosine-dependent mechanism

DOE PAGES

Kohler, Amanda C.; Mills, Matthew J. L.; Adams, Paul D.; ...

2017-04-03

Some strains of soil and marine bacteria have evolved intricate metabolic pathways for using environmentally derived aromatics as a carbon source. Many of these metabolic pathways go through intermediates such as vanillate, 3-O-methylgallate, and syringate. Demethylation of these compounds is essential for downstream aryl modification, ring opening, and subsequent assimilation of these compounds into the tricarboxylic acid (TCA) cycle, and, correspondingly, there are a variety of associated aryl demethylase systems that vary in complexity. Intriguingly, only a basic understanding of the least complex system, the tetrahydrofolate-dependent aryl demethylase LigM from Sphingomonas paucimobilis, a bacterial strain that metabolizes lignin-derived aromatics, wasmore » previously available. LigM-catalyzed demethylation enables further modification and rin g opening of the single-ring aromatics vanillate and 3-Omethylgallate, which are common byproducts of biofuel production. We characterize aryl O-demethylation by LigM and report its 1.81-Å crystal structure, revealing a unique demethylase fold and a canonical folate-binding domain. Structural homology and geometry optimization calculations enabled the identification of LigM's tetrahydrofolate-binding site and protein-folate interactions. Computationally guided mutagenesis and kinetic analyses allowed the identification of the enzyme's aryl-binding site location and determination of its unique, catalytic tyrosine-dependent reaction mechanism. This work defines LigM as a distinct demethylase, both structurally and functionally, and provides insight into demethylation and its reaction requirements. Our results afford the mechanistic details required for efficient utilization of LigM as a tool for aryl O-demethylation and as a component of synthetic biology efforts to valorize previously underused aromatic compounds.« less

Late-stage diversification of biologically active pyridazinones via a direct C-H functionalization strategy.

PubMed

Li, Wei; Fan, Zhoulong; Geng, Kaijun; Xu, Youjun; Zhang, Ao

2015-01-14

Divergent C-H functionalization reactions (arylation, carboxylation, olefination, thiolation, acetoxylation, halogenation, naphthylation) using a pyridazinone moiety as an internal directing group were successfully established. This approach offers a late-stage, ortho-selective diversification of a biologically active pyridazinone scaffold. Seven series of novel pyridazinone analogues were synthesized conveniently as the synthetic precursors of potential sortase A (SrtA) inhibitors.

9-Substituted acridine derivatives as acetylcholinesterase and butyrylcholinesterase inhibitors possessing antioxidant activity for Alzheimer's disease treatment.

PubMed

Makhaeva, Galina F; Lushchekina, Sofya V; Boltneva, Natalia P; Serebryakova, Olga G; Rudakova, Elena V; Ustyugov, Alexey A; Bachurin, Sergey O; Shchepochkin, Alexander V; Chupakhin, Oleg N; Charushin, Valery N; Richardson, Rudy J

2017-11-01

We investigated the inhibitory activity of 4 groups of novel acridine derivatives against acetylcholinesterase (AChE), butyrylcholinesterase (BChE) and carboxylesterase (CaE) using the methods of enzyme kinetics and molecular docking. Antioxidant activity of the compounds was determined using the 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS + ) radical decolorization assay as their ability to scavenge free radicals. Analysis of the esterase profiles and antiradical activities of the acridine derivatives showed that 9-aryl(heteroaryl)-N-methyl-9,10-dihydroacridines have a high radical-scavenging activity but low potency as AChE and BChE inhibitors, whereas 9-aryl(heteroaryl)-N-methyl-acridinium tetrafluoroborates effectively inhibit cholinesterases but do not exhibit antiradical activity. In contrast, a group of derivatives of 9-heterocyclic amino-N-methyl-9,10-dihydroacridine has been found that combine effective inhibition of AChE and BChE with rather high radical-scavenging activity. The results of molecular docking well explain the observed features in the efficacy, selectivity, and mechanism of cholinesterase inhibition by the acridine derivatives. Thus, in a series of acridine derivatives we have found compounds possessing dual properties of effective and selective cholinesterase inhibition together with free radical scavenging, which makes promising the use of the acridine scaffold to create multifunctional drugs for the therapy of neurodegenerative diseases. Copyright © 2017 Elsevier Ltd. All rights reserved.

Single-step synthesis of styryl phosphonic acids via palladium-catalyzed Heck coupling of vinyl phosphonic acid with aryl halides

DOE PAGES

McNichols, Brett W.; Koubek, Joshua T.; Sellinger, Alan

2017-10-27

Here, we have developed a single step palladium-catalyzed Heck coupling of aryl halides with vinyl phosphonic acid to produce functionalized (E)-styryl phosphonic acids. This pathway utilizes a variety of commercially available aryl halides, vinyl phosphonic acid and Pd(P(tBu) 3) 2 as catalyst. These conditions produce a wide range of styryl phosphonic acids with high purities and good to excellent yields (31–80%).

Single-step synthesis of styryl phosphonic acids via palladium-catalyzed Heck coupling of vinyl phosphonic acid with aryl halides

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

McNichols, Brett W.; Koubek, Joshua T.; Sellinger, Alan

Here, we have developed a single step palladium-catalyzed Heck coupling of aryl halides with vinyl phosphonic acid to produce functionalized (E)-styryl phosphonic acids. This pathway utilizes a variety of commercially available aryl halides, vinyl phosphonic acid and Pd(P(tBu) 3) 2 as catalyst. These conditions produce a wide range of styryl phosphonic acids with high purities and good to excellent yields (31–80%).

Enantioselective synthesis of chiral 3-aryl-1-indanones through rhodium-catalyzed asymmetric intramolecular 1,4-addition.

PubMed

Yu, Yue-Na; Xu, Ming-Hua

2013-03-15

Enantioselective synthesis of potentially useful chiral 3-aryl-1-indanones was achieved through a rhodium-catalyzed asymmetric intramolecular 1,4-addition of pinacolborane chalcone derivatives using extraordinary simple MonoPhos as chiral ligand under relatively mild conditions. This novel protocol offers an easy access to a wide variety of enantioenriched 3-aryl-1-indanone derivatives in high yields (up to 95%) with excellent enantioselectivities (up to 95% ee).

Induction of a chloracne phenotype in an epidermal equivalent model by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is dependent on aryl hydrocarbon receptor activation and is not reproduced by aryl hydrocarbon receptor knock down.

PubMed

Forrester, Alison R; Elias, Martina S; Woodward, Emma L; Graham, Mark; Williams, Faith M; Reynolds, Nick J

2014-01-01

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is a potent activator of the aryl hydrocarbon receptor (AhR) and causes chloracne in humans. The pathogenesis and role of AhR in chloracne remains incompletely understood. To elucidate the mechanisms contributing to the development of the chloracne-like phenotype in a human epidermal equivalent model and identify potential biomarkers. Using primary normal human epidermal keratinocytes (NHEK), we studied AhR activation by XRE-luciferase, AhR degradation and CYP1A1 induction. We treated epidermal equivalents with high affinity TCDD or two non-chloracnegens: β-naphthoflavone (β-NF) and 2-(1'H-indole-3'-carbonyl)-thiazole-4-carboxylic acid methyl ester (ITE). Using Western blotting and immunochemistry for filaggrin (FLG), involucrin (INV) and transglutaminase-1 (TGM-1), we compared the effects of the ligands on keratinocyte differentiation and development of the chloracne-like phenotype by H&E. In NHEKs, activation of an XRE-luciferase and CYP1A1 protein induction correlated with ligand binding affinity: TCDD>β-NF>ITE. AhR degradation was induced by all ligands. In epidermal equivalents, TCDD induced a chloracne-like phenotype, whereas β-NF or ITE did not. All three ligands induced involucrin and TGM-1 protein expression in epidermal equivalents whereas FLG protein expression decreased following treatment with TCDD and β-NF. Inhibition of AhR by α-NF blocked TCDD-induced AhR activation in NHEKs and blocked phenotypic changes in epidermal equivalents; however, AhR knock down did not reproduce the phenotype. Ligand-induced CYP1A1 and AhR degradation did not correlate with their chloracnegenic potential, indicating that neither CYP1A1 nor AhR are suitable biomarkers. Mechanistic studies showed that the TCDD-induced chloracne-like phenotype depends on AhR activation whereas AhR knock down did not appear sufficient to induce the phenotype. Copyright © 2013 Japanese Society for Investigative Dermatology. Published by Elsevier Ireland Ltd. All rights reserved.

Induction of a chloracne phenotype in an epidermal equivalent model by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is dependent on aryl hydrocarbon receptor activation and is not reproduced by aryl hydrocarbon receptor knock down

PubMed Central

Forrester, Alison R.; Elias, Martina S.; Woodward, Emma L.; Graham, Mark; Williams, Faith M.; Reynolds, Nick J.

2014-01-01

Background 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is a potent activator of the aryl hydrocarbon receptor (AhR) and causes chloracne in humans. The pathogenesis and role of AhR in chloracne remains incompletely understood. Objective To elucidate the mechanisms contributing to the development of the chloracne-like phenotype in a human epidermal equivalent model and identify potential biomarkers. Methods Using primary normal human epidermal keratinocytes (NHEK), we studied AhR activation by XRE-luciferase, AhR degradation and CYP1A1 induction. We treated epidermal equivalents with high affinity TCDD or two non-chloracnegens: β-naphthoflavone (β-NF) and 2-(1′H-indole-3′-carbonyl)-thiazole-4-carboxylic acid methyl ester (ITE). Using Western blotting and immunochemistry for filaggrin (FLG), involucrin (INV) and transglutaminase-1 (TGM-1), we compared the effects of the ligands on keratinocyte differentiation and development of the chloracne-like phenotype by H&E. Results In NHEKs, activation of an XRE-luciferase and CYP1A1 protein induction correlated with ligand binding affinity: TCDD > β-NF > ITE. AhR degradation was induced by all ligands. In epidermal equivalents, TCDD induced a chloracne-like phenotype, whereas β-NF or ITE did not. All three ligands induced involucrin and TGM-1 protein expression in epidermal equivalents whereas FLG protein expression decreased following treatment with TCDD and β-NF. Inhibition of AhR by α-NF blocked TCDD-induced AhR activation in NHEKs and blocked phenotypic changes in epidermal equivalents; however, AhR knock down did not reproduce the phenotype. Conclusion Ligand-induced CYP1A1 and AhR degradation did not correlate with their chloracnegenic potential, indicating that neither CYP1A1 nor AhR are suitable biomarkers. Mechanistic studies showed that the TCDD-induced chloracne-like phenotype depends on AhR activation whereas AhR knock down did not appear sufficient to induce the phenotype. PMID:24161567

Synthesis, characterization, and reactivity of arylpalladium cyanoalkyl complexes: selection of catalysts for the alpha-arylation of nitriles.

PubMed

Culkin, Darcy A; Hartwig, John F

2002-08-14

A new coupling process, the palladium-catalyzed alpha-arylation of nitriles, was developed by exploring the structure and reactivity of arylpalladium cyanoalkyl complexes. Complexes of 1,2-bis(diphenylphosphino)benzene (DPPBz), 1,1'-bis(di-i-propylphosphino)ferrocene (D(i)()PrPF), racemic-2,2'-bis(diphenylphosphino)-1,1'-binaphthyl (BINAP), and diphenylethylphosphine (PPh(2)Et) were prepared. Coordination to palladium through the alpha-carbon was observed for DPPBz-ligated complexes and for complexes of primary and benzylic nitrile anions. However, the anion of isobutyronitrile was coordinated to palladium through the cyano-nitrogen when the complex was ligated by D(i)()PrPF. The isobutyronitrile anion displaced a phosphine ligand to form a C,N-bridged dimer when generated from PPh(2)Et-ligated palladium. These results suggest that the nitrile anion preferentially coordinates to palladium through the carbon atom in the absence of steric effects. Thermolysis of the arylpalladium cyanoalkyl complexes led to reductive elimination that formed alpha-aryl nitriles. The high yields and short reaction times observed for BINAP-ligated complexes suggested that BINAP-ligated palladium catalysts might be appropriate for the arylation of nitriles. Initial results on a palladium-catalyzed process for the direct coupling of aryl bromides and primary, benzylic, and secondary nitrile anions to form alpha-aryl nitriles in good yields are reported.

Using supramolecular binding motifs to provide precise control over the ratio and distribution of species in multiple component films grafted on surfaces: demonstration using electrochemical assembly from aryl diazonium salts.

PubMed

Gui, Alicia L; Yau, Hon Man; Thomas, Donald S; Chockalingam, Muthukumar; Harper, Jason B; Gooding, J Justin

2013-04-16

Supramolecular interactions between two surface modification species are explored to control the ratio and distribution of these species on the resultant surface. A binary mixture of aryl diazonium salts bearing oppositely charged para-substituents (either -SO3(-) or -N(+)(Me)3), which also reduce at different potentials, has been examined on glassy carbon surfaces using cyclic voltammetry and X-ray photoelectron spectroscopy (XPS). Striking features were observed: (1) the two aryl diazonium salts in the mixed solution undergo reductive adsorption at the same potential which is distinctively less negative than the potential required for the reduction of either of the two aryl diazonium salts alone; (2) the surface ratio of the two phenyl derivatives is consistently 1:1 regardless of the ratio of the two aryl diazonium salts in the modification solutions. Homogeneous distribution of the two oppositely charged phenyl species on the modified surface has also been suggested by XPS survey spectra. Diffusion coefficient measurements by DOSY NMR and DFT based computation have indicated the association of the two aryl diazonium species in the solution, which has led to changes in the molecular orbital energies of the two species. This study highlights the potential of using intermolecular interactions to control the assembly of multicomponent thin layers.

The aryl hydrocarbon receptor repressor - More than a simple feedback inhibitor of AhR signaling: Clues for its role in inflammation and cancer.

PubMed

Vogel, Christoph F A; Haarmann-Stemmann, Thomas

2017-02-01

The aryl hydrocarbon receptor repressor (AhRR) was first described as a specific competitive repressor of aryl hydrocarbon receptor (AhR) activity based on its ability to dimerize with the AhR nuclear translocator (ARNT) and through direct competition of AhR/ARNT and AhRR/ARNT complexes for binding to dioxin-responsive elements (DREs). Like AhR, AhRR belongs to the basic Helix-Loop-Helix/Per-ARNT-Sim (bHLH/PAS) protein family but lacks functional ligand-binding and transactivation domains. Transient transfection experiments with ARNT and AhRR mutants examining the inhibitory mechanism of AhRR suggested a more complex mechanism than the simple mechanism of negative feedback through sequestration of ARNT to regulate AhR signaling. Recently, AhRR has been shown to act as a tumor suppressor gene in several types of cancer cells. Furthermore, epidemiological studies have found epigenetic changes and silencing of AhRR associated with exposure to cigarette smoke and cancer development. Additional studies from our laboratories have demonstrated that AhRR represses other signaling pathways including NF-κB and is capable of regulating inflammatory responses. A better understanding of the regulatory mechanisms of AhRR in AhR signaling and adverse outcome pathways leading to deregulated inflammatory responses contributing to tumor promotion and other adverse health effects is expected from future studies. This review article summarizes the characteristics of AhRR as an inhibitor of AhR activity and highlights more recent findings pointing out the role of AhRR in inflammation and tumorigenesis.

A new family of nucleophiles for photoinduced, copper-catalyzed cross-couplings via single-electron transfer: reactions of thiols with aryl halides under mild conditions (O °C).

PubMed

Uyeda, Christopher; Tan, Yichen; Fu, Gregory C; Peters, Jonas C

2013-06-26

Building on the known photophysical properties of well-defined copper-carbazolide complexes, we have recently described photoinduced, copper-catalyzed N-arylations and N-alkylations of carbazoles. Until now, there have been no examples of the use of other families of heteroatom nucleophiles in such photoinduced processes. Herein, we report a versatile photoinduced, copper-catalyzed method for coupling aryl thiols with aryl halides, wherein a single set of reaction conditions, using inexpensive CuI as a precatalyst without the need for an added ligand, is effective for a wide range of coupling partners. As far as we are aware, copper-catalyzed C-S cross-couplings at 0 °C have not previously been achieved, which renders our observation of efficient reaction of an unactivated aryl iodide at -40 °C especially striking. Mechanistic investigations are consistent with these photoinduced C-S cross-couplings following a SET/radical pathway for C-X bond cleavage (via a Cu(I)-thiolate), which contrasts with nonphotoinduced, copper-catalyzed processes wherein a concerted mechanism is believed to occur.

Synthesis of 8-Aryl-O-methylcyanidins and Their Usage for Dye-Sensitized Solar Cell Devices.

PubMed

Kimura, Yuki; Oyama, Kin-Ichi; Murata, Yasujiro; Wakamiya, Atsushi; Yoshida, Kumi

2017-02-16

Anthocyanins as natural pigments are colorful and environmentally compatible dyes for dye-sensitized solar cells (DSSCs). To increase the efficiency, we designed and synthesized unnatural O -methylflavonols and O -methylcyanidins that possess an aryl group at the 8-position. We synthesized per - O -methylquercetin from quercetin, then using selective demethylation prepared various O -methylquercetins. Using the Suzuki-Miyaura coupling reaction, 8-arylation of per - O -methylquercetin was achieved. Using a LiAlH₄ reduction or Clemmensen reduction, these flavonols were transformed to the corresponding cyanidin derivatives in satisfactory yields. Using these dyes, we fabricated DSSCs, and their efficiency was investigated. The efficiency of tetra - O -methylflavonol was 0.31%. However, the introduction of the 8-aryl residue increased the efficiency to 1.04%. In comparison to these flavonols, O -methylcyanidins exhibited a lower efficiency of 0.05% to 0.52%. The introduction of the 8-aryl group into the cyanidin derivatives did not result in a remarkable increase in the efficiency. These phenomena may be due to the poor fit of the HOMO-LUMO level of the dyes to the TiO₂ conduction band.

Cloning and heterologous expression of two aryl-aldehyde dehydrogenases from the white-rot basidiomycete Phanerochaete chrysosporium

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

Nakamura, Tomofumi; Fukuoka Institute of Health and Environmental Sciences, 39 Mukaizano, Dazaifu-shi, Fukuoka 818-0135; Ichinose, Hirofumi

2010-04-09

We identified two aryl-aldehyde dehydrogenase proteins (PcALDH1 and PcALDH2) from the white-rot basidiomycete Phanerochaete chrysosporium. Both PcALDHs were translationally up-regulated in response to exogenous addition of vanillin, one of the key aromatic compounds in the pathway of lignin degradation by basidiomycetes. To clarify the catalytic functions of PcALDHs, we isolated full-length cDNAs encoding these proteins and heterologously expressed the recombinant enzymes using a pET/Escherichia coli system. The open reading frames of both PcALDH1 and PcALDH2 consisted of 1503 nucleotides. The deduced amino acid sequences of both proteins showed high homologies with aryl-aldehyde dehydrogenases from other organisms and contained ten conservedmore » domains of ALDHs. Moreover, a novel glycine-rich motif 'GxGxxxG' was located at the NAD{sup +}-binding site. The recombinant PcALDHs catalyzed dehydrogenation reactions of several aryl-aldehyde compounds, including vanillin, to their corresponding aromatic acids. These results strongly suggested that PcALDHs metabolize aryl-aldehyde compounds generated during fungal degradation of lignin and various aromatic xenobiotics.« less

2-(Alkylamino)-3-aryl-6,7-dihydrobenzofuran-4(5H)-ones: Improved Synthesis and their Photophysical Properties

PubMed Central

Kumar, Manoj; Kumawat, Lokesh Kumar; Gupta, Vinod Kumar; Sharma, Anuj

2015-01-01

Furans are an important class of compounds and exhibit a diverse range of activities and properties. As such, improved synthetic access to furans is an important research goal. In the present report, a solvent- and catalyst-free reaction between 5,5-dimethyl-1,3-cyclohexanedione (dimedone), an aryl aldehyde and an isocyanide under microwave irradiation is presented. This method is significantly improved from previously described protocols in terms of applicability of wide ranging aryl aldehydes, better yields, shorter reaction times, facile work up and essentially no need of column chromatography. The photophysical properties of this series of compounds were studied for their possible applicability in the field of metal ion sensors. In solution, two compounds, 2-(cyclohexylamino)-3-(1H-indol-3-yl)-6,6-dimethyl-6,7-dihydrobenzofuran-4(5H)-one (1 i) and 2-(tert-butylamino)-3-(1H-indol-3-yl)-6,6-dimethyl-6,7-dihydrobenzofuran-4(5H)-one (1 j), underwent an observable color change from yellow to colorless in the presence of aluminum(III) ions. Further studies to investigate the UV absorption and luminescence behavior of these compounds revealed their utility as “naked-eye sensors” for aluminum detection. PMID:26491643

An aryl-alcohol oxidase of Pleurotus sapidus: heterologous expression, characterization, and application in a 2-enzyme system.

PubMed

Galperin, Ilya; Javeed, Aysha; Luig, Hanno; Lochnit, Günter; Rühl, Martin

2016-09-01

Aryl-alcohol oxidases (AAOs) are enzymes supporting the degradation of lignin by fungal derived class II peroxidases produced by white-rot fungi. AAOs are able to generate H2O2 as a by-product via oxidation of an aryl-alcohol into its correspondent aldehyde. In this study, an AAO was heterologously expressed in a basidiomycete host for the first time. The gene for an AAO of the white-rot fungus Pleurotus sapidus, a close relative to the oyster mushroom Pleurotus ostreatus, was cloned into an expression vector and put under control of the promotor of the glyceraldehyde-3-phosphate dehydrogenase gene 2 (gpdII) of the button mushroom Agaricus bisporus. The expression vector was transformed into the model basidiomycete Coprinopsis cinerea, and several positive transformants were obtained. The best producing transformants were grown in shake-flasks and in a stirred tank reactor reaching enzymatic activities of up to 125 U L(-1) using veratryl alcohol as a substrate. The purified AAO was biochemically characterized and compared to the previously described native and recombinant AAOs from other Pleurotus species. In addition, a two-enzyme system comprising a dye-decolorizing peroxidase (DyP) from Mycetinis scorodonius and the P. sapidus AAO was successfully employed to bleach the anthraquinone dye Reactive Blue 5.

INFRARED SPECTROSCOPY-BASED PROPERTY-REACTIVITY CORRELATIONS FOR PREDICTING ENVIRONMENTAL FATE OF ORGANIC CHEMICALS

EPA Science Inventory

A conventional structure-activity relationship (SAP) has been established between the alkaline hydrolysis rate constant (kOH) of 12 alkyl and aryl formates and acetates and the linear combination GE the frequencies of the and infrared (SR) absorbance peaks. he inability of this r...

A highly active and magnetically retrievable nanoferrite-DOPA-copper catalyst for the coupling of thiophenols with aryl halides

EPA Science Inventory

Diaryl sulfides were synthesized using magnetically recoverable heterogeneous Cu catalyst via one-pot multi component reaction using MW irradiation; the use of isopropanol as a benign reaction medium, easy recovery of the catalyst using an external magnet, efficient recycling...

Regioselective Copper-Catalyzed Amination of Chlorobenzoic Acids: Synthesis and Solid-State Structures of N-Aryl Anthranilic Acid Derivatives

PubMed Central

Mei, Xuefeng; August, Adam T.; Wolf, Christian

2008-01-01

A chemo- and regioselective copper-catalyzed cross-coupling reaction for effective amination of 2-chlorobenzoic acids with aniline derivatives has been developed. The method eliminates the need for acid protection and produces a wide range of N-aryl anthranilic acid derivatives in up to 99%. The amination was found to proceed with both electron-rich and electron-deficient aryl chlorides and anilines and also utilizes sterically hindered anilines such as 2,6-dimethylaniline and 2-tert-butylaniline. The conformational isomerism of appropriately substituted N-aryl anthranilic acids has been investigated in the solid state. Crystallographic analysis of seven anthranilic acid derivatives showed formation of two distinct supramolecular architectures exhibiting trans-anti- and unprecedented trans-syn-dimeric structures. PMID:16388629

Lanthanum Tricyanide-Catalyzed Acyl Silane-Ketone Benzoin Additions and Kinetic Resolution of Resultant α-Silyloxyketones

PubMed Central

Tarr, James C.

2010-01-01

We report the full account of our efforts on the lanthanum tricyanide-catalyzed acyl silane-ketone benzoin reaction. The reaction exhibits a wide scope in both acyl silane (aryl, alkyl) and ketone (aryl-alkyl, alkyl-alkyl, aryl-aryl, alkenyl-alkyl, alkynyl-alkyl) coupling partners. The diastereoselectivity of the reaction has been examined in both cyclic and acyclic systems. Cyclohexanones give products arising from equatorial attack by the acyl silane. The diastereoselectivity of acyl silane addition to acyclic α-hydroxy ketones can be controlled by varying the protecting group to obtain either Felkin-Ahn or chelation control. The resultant α-silyloxyketone products can be resolved with selectivity factors from 10 to 15 by subjecting racemic ketone benzoin products to CBS reduction. PMID:20392127

Synthesis and optical properties of new 5'-aryl-substituted 2,5-bis(3-decyl-2,2'-bithiophen-5-yl)-1,3,4-oxadiazoles.

PubMed

Kostyuchenko, Anastasia Sergeevna; Zheleznova, Tatyana Yu; Stasyuk, Anton Jaroslavovich; Kurowska, Aleksandra; Domagala, Wojciech; Pron, Adam; Fisyuk, Alexander S

2017-01-01

New photoluminescent donor-acceptor-donor (DAD) molecules, namely 5'-aryl-substituted 2,5-bis(3-decyl-2,2'-bithiophen-5-yl)-1,3,4-oxadiazoles were prepared by palladium-catalyzed coupling from readily available compounds such as ethyl 3-decyl-2,2'-bithiophene-5-carboxylate and aryl halides. The obtained compounds feature increasing bathochromic shifts in their emission spectra with increasing aryl-substituent size yielding blue to bluish-green emissions. At the same time, their absorption spectra are almost independent from the identity of the terminal substituent with λ max values ranging from 395 to 405 nm. The observed trends are perfectly predicted by quantum chemical DFT/TDDFT calculations carried out for these new molecules.

Synthesis and optical properties of new 5'-aryl-substituted 2,5-bis(3-decyl-2,2'-bithiophen-5-yl)-1,3,4-oxadiazoles

PubMed Central

Kostyuchenko, Anastasia Sergeevna; Zheleznova, Tatyana Yu; Stasyuk, Anton Jaroslavovich; Kurowska, Aleksandra; Domagala, Wojciech

2017-01-01

New photoluminescent donor–acceptor–donor (DAD) molecules, namely 5'-aryl-substituted 2,5-bis(3-decyl-2,2'-bithiophen-5-yl)-1,3,4-oxadiazoles were prepared by palladium-catalyzed coupling from readily available compounds such as ethyl 3-decyl-2,2'-bithiophene-5-carboxylate and aryl halides. The obtained compounds feature increasing bathochromic shifts in their emission spectra with increasing aryl-substituent size yielding blue to bluish-green emissions. At the same time, their absorption spectra are almost independent from the identity of the terminal substituent with λmax values ranging from 395 to 405 nm. The observed trends are perfectly predicted by quantum chemical DFT/TDDFT calculations carried out for these new molecules. PMID:28326140

Complete inhibition of anisomycin and UV radiation but not cytokine induced JNK and p38 activation by an aryl-substituted dihydropyrrolopyrazole quinoline and mixed lineage kinase 7 small interfering RNA.

PubMed

Wang, Xushan; Mader, Mary M; Toth, John E; Yu, Xiaohong; Jin, Najia; Campbell, Robert M; Smallwood, Jeffrey K; Christe, Michael E; Chatterjee, Arindam; Goodson, Theodore; Vlahos, Chris J; Matter, William F; Bloem, Laura J

2005-05-13

Mixed lineage kinase 7 (MLK7) is a mitogen-activated protein kinase kinase kinase (MAPKKK) that activates the pro-apoptotic signaling pathways p38 and JNK. A library of potential kinase inhibitors was screened, and a series of dihydropyrrolopyrazole quinolines was identified as highly potent inhibitors of MLK7 in vitro catalytic activity. Of this series, an aryl-substituted dihydropyrrolopyrazole quinoline (DHP-2) demonstrated an IC50 of 70 nM for inhibition of pJNK formation in COS-7 cell MLK7/JNK co-transfection assays. In stimulated cells, DHP-2 at 200 nM or MLK7 small interfering RNA completely blocked anisomycin and UV induced but had no effect on interleukin-1beta or tumor necrosis factor-alpha-induced p38 and JNK activation. Additionally, the compound blocked anisomycin and UV-induced apoptosis in COS-7 cells. Heart tissue homogenates from MLK7 transgenic mice treated with DHP-2 at 30 mg/kg had reduced JNK and p38 activation with no apparent effect on ERK activation, demonstrating that this compound can be used to block MLK7-driven MAPK pathway activation in vivo. Taken together, these data demonstrate that MLK7 is the MAPKKK required for modulation of the stress-activated MAPKs downstream of anisomycin and UV stimulation and that DHP-2 can be used to block MLK7 pathway activation in cells as well as in vivo.

Diastereoselective syntheses of 3-aryl-5-(arylalkyl)-6-methyl-1-(1-phenylethyl)thioxotetrahydropyrimidin-4(1H)-ones: a stereochemical perspective from endo and exocyclic chiral centres.

PubMed

Kumar, Varun; Raghavaiah, Pallepogu; Mobin, Shaikh M; Nair, Vipin A

2010-11-07

Diastereoselective syntheses of 3-aryl-(S/R)-6-methyl-1-[(S/R)-1-phenylethyl)]-2-thioxotetrahydro pyrimidin-4(1H)-ones were achieved in good yields by the condensation of aryl isothiocyanates with ethyl 3-(1-phenylethylamino)butanoate in a one-pot reaction. Benzylation of these substrates illustrated that the orientations of the exocylic and endocylic groups determine the stereochemical outcome of the product formed.

Substitution of the nitro group with Grignard reagents: facile arylation and alkenylation of pyridine N-oxides.

PubMed

Zhang, Fang; Zhang, Song; Duan, Xin-Fang

2012-11-02

The unprecedented substitution of a nitro group with aryl or alkenyl groups of Grignard reagents affords 2-aryl or alkenylpyridine N-oxides in modest to high yields with high chemoselectivity. This protocol allows a simple and clean synthesis of various 2-substituted pyridine N-oxides and the corresponding pyridine derivatives. Furthermore, straightforward one-pot iterative functionality of pyridine N-oxides could also be achieved simply by successive applications of two Grignard reagents.

Assembly of N,N-disubstituted hydrazines and 1-aryl-1H-indazoles via copper-catalyzed coupling reactions.

PubMed

Xiong, Xiaodong; Jiang, Yongwen; Ma, Dawei

2012-05-18

CuI-catalyzed coupling of N-acyl-N'-substituted hydrazines with aryl iodides takes place at 60-90 °C to afford N-acyl-N',N'-disubstituted hydrazines regioselectively and thereby gives a facile method for assembling N,N-diaryl hydrazines. N-Acyl-N'-substituted hydrazines can also react with 2-bromoarylcarbonylic compounds at 60-125 °C under the catalysis of CuI/4-hydroxy-l-proline to provide 1-aryl-1H-indazoles.

Photooxidation of Mixed Aryl and Biarylphosphines

PubMed Central

Zhang, Dong; Celaje, Jeff A.; Agua, Alon; Doan, Chad; Stewart, Timothy; Bau, Robert; Selke, Matthias

2010-01-01

Aryl phosphines and dialkylbiaryl phosphines react with singlet oxygen to form phosphinate esters. For mixed arylphosphines, the most electron-rich aryl group migrates to form the phosphinate, while for dialkylbiaryl phosphines migration of the alkyl group occurs. Dialkylbiaryl phosphines also yield arene epoxides, especially in electron rich systems. Phosphinate ester formation is increased at high temperature while protic solvents increase the yield of epoxide. The product distribution provides evidence for Buchwald’s recent conformational model for the aerobic oxidation of dialkylbiaryl phosphines. PMID:20527907

Reactivity of bromoselenophenes in palladium-catalyzed direct arylations.

PubMed

Skhiri, Aymen; Ben Salem, Ridha; Soulé, Jean-François; Doucet, Henri

2017-01-01

The reactivity of 2-bromo- and 2,5-dibromoselenophenes in Pd-catalyzed direct heteroarylation was investigated. From 2-bromoselenophene, only the most reactive heteroarenes could be employed to prepare 2-heteroarylated selenophenes; whereas, 2,5-dibromoselenophene generally gave 2,5-di(heteroarylated) selenophenes in high yields using both thiazole and thiophene derivatives. Moreover, sequential catalytic C2 heteroarylation, bromination, catalytic C5 arylation reactions allowed the synthesis of unsymmetrical 2,5-di(hetero)arylated selenophene derivatives in three steps from selenophene.

Access to 6a-Alkyl Aporphines: Synthesis of (±)-N-Methylguattescidine.

PubMed

Ku, Angela F; Cuny, Gregory D

2016-10-21

(-)-N-Methylguattescidine (3) is an alkaloid recently isolated from Fissistigma latifolium and assigned as a rare example of a 6a-alkyl aporphine. Herein, we report the synthesis of (±)-3 and the des-hydroxyl derivative 4 using our previously reported ortho-phenol arylation methodology mediated by the XPhos precatalyst as a key synthetic step. In addition, substituents on the aryl halide portion of the ortho-phenol arylation substrates significantly influenced the formation of an oxidized side product.

Plasmon-mediated chemical surface functionalization at the nanoscale

NASA Astrophysics Data System (ADS)

Nguyen, Mai; Lamouri, Aazdine; Salameh, Chrystelle; Lévi, Georges; Grand, Johan; Boubekeur-Lecaque, Leïla; Mangeney, Claire; Félidj, Nordin

2016-04-01

Controlling the surface grafting of species at the nanoscale remains a major challenge, likely to generate many opportunities in materials science. In this work, we propose an original strategy for chemical surface functionalization at the nanoscale, taking advantage of localized surface plasmon (LSP) excitation. The surface functionalization is demonstrated through aryl film grafting (derived from a diazonium salt), covalently bonded at the surface of gold lithographic nanostripes. The aryl film is specifically grafted in areas of maximum near field enhancement, as confirmed by numerical calculation based on the discrete dipole approximation method. The energy of the incident light and the LSP wavelength are shown to be crucial parameters to monitor the aryl film thickness of up to ~30 nm. This robust and versatile strategy opens up exciting prospects for the nanoscale confinement of functional layers on surfaces, which should be particularly interesting for molecular sensing or nanooptics.Controlling the surface grafting of species at the nanoscale remains a major challenge, likely to generate many opportunities in materials science. In this work, we propose an original strategy for chemical surface functionalization at the nanoscale, taking advantage of localized surface plasmon (LSP) excitation. The surface functionalization is demonstrated through aryl film grafting (derived from a diazonium salt), covalently bonded at the surface of gold lithographic nanostripes. The aryl film is specifically grafted in areas of maximum near field enhancement, as confirmed by numerical calculation based on the discrete dipole approximation method. The energy of the incident light and the LSP wavelength are shown to be crucial parameters to monitor the aryl film thickness of up to ~30 nm. This robust and versatile strategy opens up exciting prospects for the nanoscale confinement of functional layers on surfaces, which should be particularly interesting for molecular sensing or nanooptics. Electronic supplementary information (ESI) available: Additional figures are displayed (from Fig. SI1-SI6) to illustrate the content of the paper, including the proposed mechanisms of diazonium-derived aryl film grafting, the AFM measurements of the aryl film thickness and the calculation by the DDA method. See DOI: 10.1039/C6NR00744A

Airborne polycyclic aromatic hydrocarbons trigger human skin cells aging through aryl hydrocarbon receptor.

PubMed

Qiao, Yuan; Li, Qiang; Du, Hong-Yang; Wang, Qiao-Wei; Huang, Ye; Liu, Wei

2017-07-01

Accumulating evidence suggests that polycyclic aromatic hydrocarbons (PAH) which adsorbed on the surface of ambient air particulate matters (PM), are the major toxic compound to cause cardiovascular and respiratory diseases, even cancer. However, its detrimental effects on human skin cell remain unclear. Here, we demonstrated that SRM1649b, a reference urban dust material of PAH, triggers human skin cells aging through cell cycle arrest, cell growth inhibition and apoptosis. Principally, SRM1649b facilitated Aryl hydrocarbon receptor (AhR) translocated into nucleus, subsequently activated ERK/MAPK signaling pathway, and upregulated aging-related genes expression. Most important, we found that AhR antagonist efficiently revert the aging of skin cells. Thus our novel findings firstly revealed the mechanism of skin aging under PAH contamination and provided potential strategy for clinical application. Copyright © 2017. Published by Elsevier Inc.

MOF-based catalysts for selective hydrogenolysis of carbon–oxygen ether bonds

DOE PAGES

Stavila, Vitalie; Parthasarathi, Ramakrishnan; Davis, Ryan W.; ...

2015-11-23

We demonstrate that metal–organic frameworks (MOFs) can catalyze hydrogenolysis of aryl ether bonds under mild conditions. Mg-IRMOF-74(I) and Mg-IRMOF-74(II) are stable under reducing conditions and can cleave phenyl ethers containing β-O-4, α-O-4, and 4-O-5 linkages to the corresponding hydrocarbons and phenols. Reaction occurs at 10 bar H 2 and 120 °C without added base. DFT-optimized structures and charge transfer analysis suggest that the MOF orients the substrate near Mg 2+ ions on the pore walls. Ti and Ni doping further increase conversions to as high as 82% with 96% selectivity for hydrogenolysis versus ring hydrogenation. Thus repeated cycling induces nomore » loss of activity, making this a promising route for mild aryl-ether bond scission.« less

Spiroborate Ester-Mediated Asymmetric Synthesis of β-Hydroxy Ethers and its Conversion to Highly Enantiopure β-Amino Ethers

PubMed Central

Huang, Kun; Ortiz-Marciales, Margarita; Correa, Wildeliz; Pomales, Edgardo; López, Xaira Y.

2009-01-01

Borane-mediated reduction of aryl and alkyl ketones with α-aryl- and α-pyridyloxy groups affords β-hydroxy ethers in high enantiomeric purity (up to 99% ee) and in good yield, using as catalyst 10 mol % of spiroborate ester 1 derived from (S)-diphenylprolinol. Representative β-hydroxy ethers are successfully converted to β-amino ethers, with minor epimerization, by phthalimide substitution under Mitsunobu’s conditions followed by hydrazinolysis, to obtain primary amino ethers or by imide reduction with borane to afford β-2,3-dihydro-1H-isoindol ethers. Non-racemic Mexiletine and nAChR analogues with potential biological activity are also synthesized in excellent yield by mesylation of key β-hydroxy pyridylethers and substitution with 5, 6 and 7 member ring heterocyclic amines. PMID:19413288

Z-Selective iridium-catalyzed cross-coupling of allylic carbonates and α-diazo esters.

PubMed

Thomas, Bryce N; Moon, Patrick J; Yin, Shengkang; Brown, Alex; Lundgren, Rylan J

2018-01-07

A well-defined Ir-allyl complex catalyzes the Z -selective cross-coupling of allyl carbonates with α-aryl diazo esters. The process overrides the large thermodynamic preference for E -products typically observed in metal-mediated coupling reactions to enable the synthesis of Z , E -dieneoates in good yield with selectivities consistently approaching or greater than 90 : 10. This transformation represents the first productive merger of Ir-carbene and Ir-allyl species, which are commonly encountered intermediates in allylation and cyclopropanation/E-H insertion catalysis. Potentially reactive functional groups (aryl halides, ketones, nitriles, olefins, amines) are tolerated owing to the mildness of reaction conditions. Kinetic analysis of the reaction suggests oxidative addition of the allyl carbonate to an Ir-species is rate-determining. Mechanistic studies uncovered a pathway for catalyst activation mediated by NEt 3 .

Regioselective reaction: synthesis and pharmacological study of Mannich bases containing ibuprofen moiety.

PubMed

Sujith, K V; Rao, Jyothi N; Shetty, Prashanth; Kalluraya, Balakrishna

2009-09-01

A series of 4-[(4-aryl)methylidene]amino-2-(substituted-4-ylmethyl)-5-{1-[4-(2-methylpropyl)phenyl]ethyl}-2,4-dihydro-3H-1,2,4-triazole-3-thione (6) were synthesized from an arylpropionic acid namely, ibuprofen by a three-component Mannich reaction. Aminomethylation of 4-[(4-aryl)methylidene]amino-5-{1-[4-(2-methylpropyl)phenyl] ethyl}-4H-1,2,4-triazole-3-thiol (5) with formaldehyde and a secondary amine furnished this novel series of Mannich bases (6). Both Schiff bases (5) and Mannich bases (6) were well characterized on the basis of IR, NMR, mass spectral data and elemental analysis. They were screened for their anti-inflammatory, analgesic, antibacterial and antifungal activities. Some of the Mannich bases (6) carrying morpholino and N-methylpiperazino residues were found to be promising anti-inflammatory and analgesic agents.

Fabrication and characterization of graphene/molecule/graphene vertical junctions with aryl alkane monolayers

NASA Astrophysics Data System (ADS)

Jeong, Inho; Song, Hyunwook

2017-11-01

In this study, we fabricated and characterized graphene/molecule/graphene (GMG) vertical junctions with aryl alkane monolayers. The constituent molecules were chemically self-assembled via electrophilic diazonium reactions into a monolayer on the graphene bottom electrode, while the other end physically contacted the graphene top electrode. A full understanding of the transport properties of molecular junctions is a key step in the realization of molecular-scale electronic devices and requires detailed microscopic characterization of the junction's active region. Using a multiprobe approach combining a variety of transport techniques, we elucidated the transport mechanisms and electronic structure of the GMG junctions, including temperature- and length-variable transport measurements, and transition voltage spectroscopy. These results provide criteria to establish a valid molecular junction and to determine the most probable transport characteristics of the GMG junctions.

Fluorine bearing sydnones with styryl ketone group: synthesis and their possible analgesic and anti-inflammatory activities.

PubMed

Deshpande, Shreenivas Ramachandrarao; Pai, Karkala Vasantakumar

2012-04-01

In continuation of structure activity relationship studies, a panel of fluorine containing sydnones with styryl ketone group 4-[1-oxo-3-(substituted aryl)-2-propenyl]-3-(3-chloro-4-fluorophenyl)sydnones 2a-i, was synthesized as better analgesic and anti-inflammatory agents. The title compounds were formed by condensing 4-acetyl-3-(3-chloro-4-fluorophenyl)sydnone with various substituted aryl aldehydes, characterized by spectral studies and evaluated at 100 mg\\kg b.w., p.o. for analgesic, anti-inflammatory and ulcerogenic activities. Compounds 2c and 2e showed good analgesic effect in acetic acid-induced writhing while none showed significant activity in hot plate assay in mice. In carrageenan-induced rat paw oedema test, compound 2c and 2f exhibited good anti-inflammatory effect at 3rd h, whereas compounds 2c, 2e, 2d, 2g and 2h showed activity in croton oil induced ear oedema assay in mice. Compounds 2c and 2e were less ulcerogenic than ibuprofen in rats, when tested by ulcer index method. Compounds with electron attracting substituents such as 2c and 2e were found to be promising in terms of the ratio of efficacy and adverse effect. These compounds generally exhibited better activity than those of earlier series signifying fluorine substitution.

Decreased Expression of the Aryl Hydrocarbon Receptor in Ocular Behcet's Disease

PubMed Central

Wang, Chaokui; Ye, Zi; Kijlstra, Aize; Zhou, Yan; Yang, Peizeng

2014-01-01

Recent studies show that the aryl hydrocarbon receptor (AhR) is involved in immune responses. AhR is activated following interaction with its ligands, such as 6-formylindolo[3,2-b]carbazole (FICZ) and 2-(1′H-indole-3′-carbonyl)-thiazole-4-carboxylic acid methyl ester (ITE). In this study, we investigated the role of AhR activation by its endogenous ligands in the pathogenesis of ocular Behcet's disease (BD). The expression of AhR was significantly decreased in active BD patients as compared to inactive BD patients and normal controls. Both FICZ and ITE inhibited Th1 and Th17 polarization and induced the expression of IL-22 by PBMCs and by CD4+T cells in active BD patients and normal controls. Stimulation of purified CD4+T cells with FICZ or ITE caused a decreased expression of RORC, IL-17, IL-23R, and CCR6 and an increased phosphorylation of STAT3 and STAT5. The present study suggests that a decreased AhR expression is associated with disease activity in BD patients. The activation of AhR by either FICZ or ITE was able to inhibit Th1 and Th17 cell polarization. Further studies are needed to investigate whether modulation of AhR might be used in the treatment of BD. PMID:25045206

High aryl acylamidase activity associated with cobra venom acetylcholinesterase: biological significance.

PubMed

Rajesh, Ramanna V; Layer, Paul G; Boopathy, Rathanam

2009-01-01

Investigation of the non-classical functions of cholinesterases (ChEs) has been the subject of interest in the past three decades. One of which is aryl acylamidase (AAA) activity associated with ChEs, but characterized in in vitro, as an enzyme, splitting the artificial substrate o-nitroacetanilide with unknown physiological function. In the present study, we have compared levels of AAA activity of AChE from different sources like goat brain, electric eel organ and from venoms of different snakes. Remarkably cobra venom showed the highest AAA activity and also high AAA/AChE ratio. Both serotonergenic and cholinergic inhibitors inhibited the cobra venom AAA activity in a concentration dependent manner, which also underlines the association of AAA with AChE of cobra venom. The study becomes interesting because of i) the cobra venom AChE exists in monomeric globular forms; ii) in Alzheimer's disease too the most abundant forms of cholinesterases are monomeric globular forms, thought to be involved in the pathogenesis of Alzheimer's disease; iii) the effect of Alzheimer's disease drugs on the AAA activity of cobra venom, indicated that AAA activity of cobra venom was more sensitive than AChE and iv) Huperzine and Tacrine showed more pronounced effect on AAA. Thus, this study elucidates the high AAA associated with cobra venom AChE may serve as one of the prominent activity to test the pharmacological effect of AD drugs, as other sources were found to have lower activity.

Aryl acylamidase activity exhibited by butyrylcholinesterase is higher in chick than in horse, but much lower than in fetal calf serum.

PubMed

Weitnauer, E; Robitzki, A; Layer, P G

1998-10-02

Several side activities have been attributed to butyrylcholinesterase (BChE), including aryl acylamidase (AAA) activity, which is an amidase-like activity with unknown physiological function splitting the artificial substrate o-nitroacetanilide. For avians, extensive developmental data have pointed to neurogenetic functions of BChE, however, a possible AAA activity of BChE has not been studied. In this study, we first compare the relative levels of AAA exhibited by BChE in whole sera from chick, fetal calves (FCS) and horse. Remarkably, FCS exhibits a 400-fold higher ratio of AAA/BChE than horse and 80-fold higher than chick serum. We then show that an immunoisolated preparation of BChE from chicken serum presents significant activity for AAA. Both in sera and with the purified enzyme, the AAA activity is fully inhibited by anticholinesterase drugs, showing that AAA activity is exclusively conveyed by the BChE molecule. Noticeably, AAA inhibition even occurs at lower drug concentrations than that of BChE activity itself. Moreover, AAA is sensitive to serotonin. These data indicate that (1) AAA is a general feature of serum BChE of vertebrates including avians, (2) AAA is effectively inhibited by cholinergic and serotonergic agents, and (3) AAA may have a developmental role, since it is much pronounced in a serum from fetal animals. Functionally, deamination of neuropeptides, a link between cholinergic and serotonergic neurotransmitter systems, and roles in lipoprotein metabolism could be relevant.

The tertiary structures of porcine AhR and ARNT proteins and molecular interactions within the TCDD/AhR/ARNT complex.

PubMed

Orlowska, Karina; Molcan, Tomasz; Swigonska, Sylwia; Sadowska, Agnieszka; Jablonska, Monika; Nynca, Anna; Jastrzebski, Jan P; Ciereszko, Renata E

2016-06-01

The aryl hydrocarbon receptor (AhR) is a ligand-dependent transcription factor that can be activated by structurally diverse synthetic and natural chemicals, including toxic environmental contaminant 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). In the present study, homology models of the porcine AhR-ligand binding domain (LBD) and the porcine aryl hydrocarbon receptor nuclear translocator-ligand binding domain (ARNT-LBD) were created on the basis of structures of closely related respective proteins i.e., human Hif-2α and ARNT. Molecular docking of TCDD to the porcine AhR-LBD model revealed high binding affinity (-8.8kcal/mol) between TCDD and the receptor. Moreover, formation of the TCDD/AhR-LBD complex was confirmed experimentally with the use of electrophoretic mobility shift assay (EMSA). It was found that TCDD (10nM, 2h of incubation) not only bound to the AhR in the porcine granulosa cells but also activated the receptor. The current study provides a framework for examining the key events involved in the ligand-dependent activation of the AhR. Copyright © 2016 Elsevier Inc. All rights reserved.

Pd-Catalyzed N-Arylation of Secondary Acyclic Amides: Catalyst Development, Scope, and Computational Study

PubMed Central

Hicks, Jacqueline D.; Hyde, Alan M.; Cuezva, Alberto Martinez; Buchwald, Stephen L.

2009-01-01

We report the efficient N-arylation of acyclic secondary amides and related nucleophiles with aryl nonaflates, triflates, and chlorides. This method allows for easy variation of the aromatic component in tertiary aryl amides. A new biaryl phosphine with P-bound 3,5-(bis)trifluoromethylphenyl groups was found to be uniquely effective for this amidation. The critical aspects of the ligand were explored through synthetic, mechanistic, and computational studies. Systematic variation of the ligand revealed the importance of (1) a methoxy group on the aromatic carbon of the “top ring” ortho to the phosphorus and (2) two highly electron-withdrawing P-bound 3,5-(bis)trifluoromethylphenyl groups. Computational studies suggest the electron-deficient nature of the ligand is important in facilitating amide binding to the LPd(II)(Ph)(X) intermediate. PMID:19886610

Aryl Polyenes, a Highly Abundant Class of Bacterial Natural Products, Are Functionally Related to Antioxidative Carotenoids.

PubMed

Schöner, Tim A; Gassel, Sören; Osawa, Ayako; Tobias, Nicholas J; Okuno, Yukari; Sakakibara, Yui; Shindo, Kazutoshi; Sandmann, Gerhard; Bode, Helge B

2016-02-02

Bacterial pigments of the aryl polyene type are structurally similar to the well-known carotenoids with respect to their polyene systems. Their biosynthetic gene cluster is widespread in taxonomically distant bacteria, and four classes of such pigments have been found. Here we report the structure elucidation of the aryl polyene/dialkylresorcinol hybrid pigments of Variovorax paradoxus B4 by HPLC-UV-MS, MALDI-MS and NMR. Furthermore, we show for the first time that this pigment class protects the bacterium from reactive oxygen species, similarly to what is known for carotenoids. An analysis of the distribution of biosynthetic genes for aryl polyenes and carotenoids in bacterial genomes is presented; it shows a complementary distribution of these protective pigments in bacteria. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Functional expression and regulation of drug transporters in monolayer- and sandwich-cultured mouse hepatocytes.

PubMed

Noel, Gregory; Le Vee, Marc; Moreau, Amélie; Stieger, Bruno; Parmentier, Yannick; Fardel, Olivier

2013-04-11

Primary hepatocyte cultures are now considered as convenient models for in vitro analyzing liver drug transport. However, if primary human and rat hepatocytes have been well-characterized with respect to drug transporter expression and regulation, much less is known for primary mouse hepatocytes. The present study was therefore designed to gain insights about this point. The profile of sinusoidal and canalicular drug transporter mRNA expression in short time (4h)-cultured mouse hepatocytes was found to be highly correlated with that of freshly isolated hepatocytes; by contrast, those of counterparts cultured for a longer time (until 4 days) either in monolayer configurations on plastic or collagen or in sandwich configuration with matrigel were profoundly altered: uptake drug transporters such as Oct1, Oatps and Oat2 were thus down-regulated, whereas most of efflux transporters such as Mdr1a/b, Mrp3, Mrp4 and Bcrp were induced. Moreover, short time-cultured hepatocytes exhibited the highest levels of sinusoidal influx transporter activities. Transporter-mediated drug secretion into canalicular networks was however only observed in sandwich-cultured hepatocytes. Mouse hepatocytes cultured either in monolayer or sandwich configurations were finally shown to exhibit up-regulation of referent transporters in response to exposure to prototypical activators of the drug sensing receptors pregnane X receptor, aryl hydrocarbon receptor or constitutive androstane receptor. Taken together, these data demonstrate the feasibility of using primary mouse hepatocytes for investigating potential interactions of xenobiotics with hepatic transporter activity or regulation, provided that adequate culture conditions are retained. Copyright © 2013 Elsevier B.V. All rights reserved.

Antioxidative activity of the olive oil constituent hydroxy-1-aryl-isochromans in cells and cell-free systems.

PubMed

Schönfeld, Peter; Kruska, Nicol; Reiser, Georg

2009-12-01

Hydroxy-1-aryl-isochromans (HAIC) are newly emerging natural polyphenolic antioxidants, enriched in extravirgin olive oil, whose antioxidative potency was only scarcely characterized using cell-free systems and cells. We characterized the activity of HAIC to inactivate reactive oxygen species (ROS) generated by the xanthine/xanthine oxidase system, mitochondria (rat brain) and neural cells. ROS levels were estimated using ROS-sensitive probes, such as Amplex Red, MitoSOXRED. HAIC (with 2, 3 or 4 hydroxyl substituents) effectively scavenge ROS released from mitochondria. EC50 values estimated with mitochondria and submitochondrial particles were around 20 microM. Moreover, in PC12 and cultured neural primary cells, HAIC buffered cytosolic ROS. Although HAIC permeate biological membranes, HAIC fail to buffer matrix ROS in isolated mitochondria. We show that hydrogen peroxide was effectively abolished by HAIC, whereas the production of superoxide was not affected. HAIC exert high antioxidative activity to reduce hydrogen peroxide. The antioxidative activity of HAIC is comparable with that of the stilbene-like, polyphenolic resveratrol, but much higher than that of trolox, N-acetylcysteine or melatonin. Unlike resveratrol, HAIC do not impair mitochondrial ATP synthesis or Ca2+ retention by mitochondria. Thus, HAIC have the decisive advantage to be potent antioxidants with no detrimental side effects on mitochondrial functions.

Binding Mode and Structure-Activity Relationships of ITE as an Aryl Hydrocarbon Receptor (AhR) Agonist.

PubMed

Dolciami, Daniela; Gargaro, Marco; Cerra, Bruno; Scalisi, Giulia; Bagnoli, Luana; Servillo, Giuseppe; Fazia, Maria Agnese Della; Puccetti, Paolo; Quintana, Francisco J; Fallarino, Francesca; Macchiarulo, Antonio

2018-02-06

Discovered as a modulator of the toxic response to environmental pollutants, aryl hydrocarbon receptor (AhR) has recently gained attention for its involvement in various physiological and pathological pathways. AhR is a ligand-dependent transcription factor activated by a large array of chemical compounds, which include metabolites of l-tryptophan (l-Trp) catabolism as endogenous ligands of the receptor. Among these, 2-(1'H-indole-3'-carbonyl)thiazole-4-carboxylic acid methyl ester (ITE) has attracted interest in the scientific community, being endowed with nontoxic, immunomodulatory, and anticancer AhR-mediated functions. So far, no information about the binding mode and interactions of ITE with AhR is available. In this study, we used docking and molecular dynamics to propose a putative binding mode of ITE into the ligand binding pocket of AhR. Mutagenesis studies were then instrumental in validating the proposed binding mode, identifying His 285 and Tyr 316 as important key residues for ligand-dependent receptor activation. Finally, a set of ITE analogues was synthesized and tested to further probe molecular interactions of ITE to AhR and characterize the relevance of specific functional groups in the chemical structure for receptor activity. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

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.

Oxidative coupling of sp 2 and sp 3 carbon-hydrogen bonds to construct dihydrobenzofurans.

PubMed

Shi, Jiang-Ling; Wang, Ding; Zhang, Xi-Sha; Li, Xiao-Lei; Chen, Yu-Qin; Li, Yu-Xue; Shi, Zhang-Jie

2017-08-10

Metal-catalyzed cross-couplings provide powerful, concise, and accurate methods to construct carbon-carbon bonds from organohalides and organometallic reagents. Recent developments extended cross-couplings to reactions where one of the two partners connects with an aryl or alkyl carbon-hydrogen bond. From an economic and environmental point of view, oxidative couplings between two carbon-hydrogen bonds would be ideal. Oxidative coupling between phenyl and "inert" alkyl carbon-hydrogen bonds still awaits realization. It is very difficult to develop successful strategies for oxidative coupling of two carbon-hydrogen bonds owning different chemical properties. This article provides a solution to this challenge in a convenient preparation of dihydrobenzofurans from substituted phenyl alkyl ethers. For the phenyl carbon-hydrogen bond activation, our choice falls on the carboxylic acid fragment to form the palladacycle as a key intermediate. Through careful manipulation of an additional ligand, the second "inert" alkyl carbon-hydrogen bond activation takes place to facilitate the formation of structurally diversified dihydrobenzofurans.Cross-dehydrogenative coupling is finding increasing application in synthesis, but coupling two chemically distinct sites remains a challenge. Here, the authors report an oxidative coupling between sp 2 and sp 3 carbons by sequentially activating the more active aryl site followed by the alkyl position.

Synthesis, in vitro β-glucuronidase inhibitory activity and in silico studies of novel (E)-4-Aryl-2-(2-(pyren-1-ylmethylene)hydrazinyl)thiazoles.

PubMed

Salar, Uzma; Khan, Khalid Mohammed; Syed, Shazia; Taha, Muhammad; Ali, Farman; Ismail, Nor Hadiani; Perveen, Shahnaz; Wadood, Abdul; Ghufran, Mehreen

2017-02-01

Current research is based on the synthesis of novel (E)-4-aryl-2-(2-(pyren-1-ylmethylene)hydrazinyl)thiazole derivatives (3-15) by adopting two steps route. First step was the condensation between the pyrene-1-carbaldehyde (1) with the thiosemicarbazide to afford pyrene-1-thiosemicarbazone intermediate (2). While in second step, cyclization between the intermediate (2) and phenacyl bromide derivatives or 2-bromo ethyl acetate was carried out. Synthetic derivatives were structurally characterized by spectroscopic techniques such as EI-MS, 1 H NMR and 13 C NMR. Stereochemistry of the iminic double bond was confirmed by NOESY analysis. All pure compounds 2-15 were subjected for in vitro β-glucuronidase inhibitory activity. All molecules were exhibited excellent inhibition in the range of IC 50 =3.10±0.10-40.10±0.90μM and found to be even more potent than the standard d-saccharic acid 1,4-lactone (IC 50 =48.38±1.05μM). Molecular docking studies were carried out to verify the structure-activity relationship. A good correlation was perceived between the docking study and biological evaluation of active compounds. Copyright © 2016 Elsevier Inc. All rights reserved.

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

Hypoxia perturbs aryl hydrocarbon receptor signaling and CYP1A1 expression induced by PCB 126 in human skin and liver-derived cell lines

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

Vorrink, Sabine U.; Department of Radiation Oncology, The University of Iowa, Iowa City, IA; Severson, Paul L.

2014-02-01

The aryl hydrocarbon receptor (AhR) is an important mediator of toxic responses after exposure to xenobiotics including 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and dioxin-like polychlorinated biphenyls (PCBs). Activation of AhR responsive genes requires AhR dimerization with the aryl hydrocarbon receptor nuclear translocator (ARNT), a heterodimeric partner also shared by the hypoxia-inducible factor-1α (HIF-1α) protein. TCDD-stimulated AhR transcriptional activity can be influenced by hypoxia; however, it less well known whether hypoxia interferes with AhR transcriptional transactivation in the context of PCB-mediated AhR activation in human cells. Elucidation of this interaction is important in liver hepatocytes which extensively metabolize ingested PCBs and experience varying degreesmore » of oxygen tension during normal physiologic function. This study was designed to assess the effect of hypoxia on AhR transcriptional responses after exposure to 3,3′,4,4′,5-pentachlorobiphenyl (PCB 126). Exposure to 1% O{sub 2} prior to PCB 126 treatment significantly inhibited CYP1A1 mRNA and protein expression in human HepG2 and HaCaT cells. CYP1A1 transcriptional activation was significantly decreased upon PCB 126 stimulation under conditions of hypoxia. Additionally, hypoxia pre-treatment reduced PCB 126 induced AhR binding to CYP1 target gene promoters. Importantly, ARNT overexpression rescued cells from the inhibitory effect of hypoxia on XRE-luciferase reporter activity. Therefore, the mechanism of interference of the signaling crosstalk between the AhR and hypoxia pathways appears to be at least in part dependent on ARNT availability. Our results show that AhR activation and CYP1A1 expression induced by PCB 126 were significantly inhibited by hypoxia and hypoxia might therefore play an important role in PCB metabolism and toxicity. - Highlights: • Significant crosstalk exists between AhR and HIF-1α signaling. • Hypoxia perturbs PCB 126 induced AhR function and target gene expression. • PCB 126 mediated activation of AhR activity inhibits HIF-1α signaling. • AhR binding to CYP1A1 and CYP1B1 promoters is inhibited by hypoxia. • ARNT overexpression relieves hypoxic inhibition of AhR function.« less

Improved synthesis of aryltrialkoxysilanes via treatment of aryl Grignard or lithium reagents with tetraalkyl orthosilicates.

PubMed

Manoso, Amy S; Ahn, Chuljin; Soheili, Arash; Handy, Christopher J; Correia, Reuben; Seganish, W Michael; Deshong, Philip

2004-11-26

General reaction conditions for the synthesis of aryl(trialkoxy)silanes from aryl Grignard and lithium reagents and tetraalkyl orthosilicates (Si(OR)(4)) have been developed. Ortho-, meta-, and para-substituted bromoarenes underwent efficient metalation and silylation at low temperature to provide aryl siloxanes. Mixed results were obtained with heteroaromatic substrates: 3-bromothiophene, 3-bromo-4-methoxypyridine, 5-bromoindole, and N-methyl-5-bromoindole underwent silylation in good yield, whereas a low yield of siloxane was obtained from 2-bromofuran, and 2-bromopyridine failed to give silylated product. The synthesis of siloxanes via organolithium and magnesium reagents was limited by the formation of di- and triarylated silanes (Ar(2)Si(OR)(2) and Ar(3)SiOR, respectively) and dehalogenated (Ar-H) byproducts. Silylation at low temperature gave predominantly monoaryl siloxanes, without requiring a large excess of the electrophile. Optimal reaction conditions for the synthesis of siloxanes from aryl Grignard reagents entailed addition of arylmagnesium reagents to 3 equiv of tetraethyl- or tetramethyl orthosilicate at -30 degrees C in THF. Aryllithium species were silylated using 1.5 equiv of tetraethyl- or tetramethyl orthosilicate at -78 degrees C in ether.

Synthesis of 8-Aryl-O-methylcyanidins and Their Usage for Dye-Sensitized Solar Cell Devices

PubMed Central

Kimura, Yuki; Oyama, Kin-ichi; Murata, Yasujiro; Wakamiya, Atsushi; Yoshida, Kumi

2017-01-01

Anthocyanins as natural pigments are colorful and environmentally compatible dyes for dye-sensitized solar cells (DSSCs). To increase the efficiency, we designed and synthesized unnatural O-methylflavonols and O-methylcyanidins that possess an aryl group at the 8-position. We synthesized per-O-methylquercetin from quercetin, then using selective demethylation prepared various O-methylquercetins. Using the Suzuki-Miyaura coupling reaction, 8-arylation of per-O-methylquercetin was achieved. Using a LiAlH4 reduction or Clemmensen reduction, these flavonols were transformed to the corresponding cyanidin derivatives in satisfactory yields. Using these dyes, we fabricated DSSCs, and their efficiency was investigated. The efficiency of tetra-O-methylflavonol was 0.31%. However, the introduction of the 8-aryl residue increased the efficiency to 1.04%. In comparison to these flavonols, O-methylcyanidins exhibited a lower efficiency of 0.05% to 0.52%. The introduction of the 8-aryl group into the cyanidin derivatives did not result in a remarkable increase in the efficiency. These phenomena may be due to the poor fit of the HOMO-LUMO level of the dyes to the TiO2 conduction band. PMID:28212330

In situ diazonium-modified flexible ITO-coated PEN substrates for the deposition of adherent silver-polypyrrole nanocomposite films.

PubMed

Samanta, Soumen; Bakas, Idriss; Singh, Ajay; Aswal, Dinesh K; Chehimi, Mohamed M

2014-08-12

In this paper, we report a simple and versatile process of electrografting the aryl multilayers onto indium tin oxide (ITO)-coated flexible poly(ethylene naphthalate) (PEN) substrates using a diazonium salt (4-pyrrolylphenyldiazonium) solution, which was generated in situ from a reaction between the 4-(1H-pyrrol-1-yl)aniline precursor and sodium nitrite in an acidic medium. The first aryl layer bonds with the ITO surface through In-O-C and Sn-O-C bonds which facilitate the formation of a uniform aryl multilayer that is ∼8 nm thick. The presence of the aryl multilayer has been confirmed by impedance spectroscopy as well as by electron-transfer blocking measurements. These in situ diazonium-modified ITO-coated PEN substrates may find applications in flexible organic electronics and sensor industries. Here we demonstrate the application of diazonium-modified flexible substrates for the growth of adherent silver/polpyrrole nanocomposite films using surface-confined UV photopolymerization. These nanocomposite films have platelet morphology owing to the template effect of the pyrrole-terminated aryl multilayers. In addition, the films are highly doped (32%). This work opens new areas in the design of flexible ITO-conductive polymer hybrids.

Flavonoids and Asthma

PubMed Central

Tanaka, Toshio; Takahashi, Ryo

2013-01-01

Asthma is a chronic disease, characterized by airway inflammation, airflow limitation, hyper-reactivity and airway remodeling. It is believed that asthma is caused by the interaction between genetic and environmental factors. The prevalence of allergic diseases, including asthma, has increased worldwide during the past two decades. Although the precise reasons that have caused this increase remain unknown, dietary change is thought to be one of the environmental factors. Flavonoids, which are polyphenolic plant secondary metabolites ubiquitously present in vegetables, fruits and beverages, possess antioxidant and anti-allergic traits, as well as immune-modulating activities. Flavonoids are powerful antioxidants and anti-allergic nutrients that inhibit the release of chemical mediators, synthesis of Th2 type cytokines, such as interleukin (IL)-4 and IL-13, and CD40 ligand expression by high-affinity immunoglobulin E (IgE) receptor-expressing cells, such as mast cells and basophils. They also inhibit IL-4-induced signal transduction and affect the differentiation of naïve CD4+ T cells into effector T-cells through their inhibitory effect on the activation of the aryl hydrocarbon receptor. Various studies of flavonoids in asthmatic animal models have demonstrated their beneficial effects. The results of several epidemiological studies suggest that an increase in flavonoid intake is beneficial for asthma. Moreover, clinical trials of flavonoids have shown their ameliorative effects on symptoms related to asthma. However, these human studies are currently limited; further validation is required to clarify whether an appropriate intake of flavonoids may constitute dietary treatment and for part of a preventive strategy for asthma. PMID:23752494

Toxicogenomic assessment of 6-OH-BDE47 induced developmental toxicity in chicken embryo

EPA Science Inventory

Hydroxylated and methoxylated polybrominated diphenyl ethers (OH-/MeO-PBDEs) are analogs of PBDEs with hundreds of possible structures and many of them can activate aryl hydrocarbon receptor (AhR), however, the in vivo evidence on the toxicity of OH-/MeO-PBDEs are still very limi...

Rhodium-Catalyzed Boron Arylation of 1,2-Azaborines**

PubMed Central

Rudebusch, Gabriel E.; Zakharov, Lev N.; Liu, Shih-Yuan

2013-01-01

A Sn-phony in B! BN isosteres of biphenyl compounds are prepared through Rh-catalyzed cross-coupling between 2-chloro-1,2-azaborines and arylstannanes (see scheme). The synthetic method should enable investigations of structure–activity relationships (SARs) by expanding the chemical space of the pharmaceutically relevant biphenyl structure through BN/CC isosterism. PMID:23832871

Identification of the stereochemical requirements in the 4-aryl-2-cycloalkylidenhydrazinylthiazole scaffold for the design of selective human monoamine oxidase B inhibitors.

PubMed

D'Ascenzio, Melissa; Carradori, Simone; Secci, Daniela; Mannina, Luisa; Sobolev, Anatoly P; De Monte, Celeste; Cirilli, Roberto; Yáñez, Matilde; Alcaro, Stefano; Ortuso, Francesco

2014-05-15

Exploring the effect that substituents on the cycloaliphatic ring had on the inhibitory activity against human monoamine oxidase B of a series of 4-aryl-2-cycloalkylidenhydrazinylthiazoles led to the synthesis of a new series of 2-methylcyclopentyl and 3-methylcyclopentyl derivatives which were tested in vitro as mixtures of diastereoisomers. In fact, due to the presence of a chiral center on the cycloaliphatic ring and a trisubstituted CN bond, they exist as four diastereoisomers ((E)-(R), (E)-(S), (Z)-(R), (Z)-(S)). 4-(2,4-Difluorophenyl)-2-(2-(3-methylcyclopentylidene)hydrazinyl)thiazole was chosen as a model to investigate the influence of stereochemical requirements on the inhibitory activity against hMAO-B of these derivatives after a stereoconservative synthesis and semi-preparative HPLC diastereoseparation. (R)-(Z) isomer of this compound was endowed with a potent and selective hMAO-B inhibition higher than that of reference drugs as also corroborated by molecular modeling studies. Copyright © 2014 Elsevier Ltd. All rights reserved.

Cytotoxic Activity and Structure-Activity Relationship of Triazole-Containing Bis(Aryl Ether) Macrocycles.

PubMed

Hernández-Vázquez, Eduardo; Chávez-Riveros, Alejandra; Romo-Pérez, Adriana; Ramírez-Apán, María Teresa; Chávez-Blanco, Alma D; Morales-Bárcenas, Rocío; Dueñas-González, Alfonso; Miranda, Luis D

2018-05-17

Cancer continues to be a worldwide health problem. Certain macrocyclic molecules have become attractive therapeutic alternatives for this disease because of their efficacy and, frequently, their novel mechanisms of action. Herein, we report the synthesis of a series of 20-, 21-, and 22-membered macrocycles containing triazole and bis(aryl ether) moieties. The compounds were prepared by a multicomponent approach from readily available commercial substrates. Notably, some of the compounds displayed interesting cytotoxicity against cancer (PC-3) and breast (MCF-7) cell lines, especially those bearing an aliphatic or a trifluoromethyl substituent on the N-phenyl moiety (IC 50 <13 μm). Additionally, some of the compounds were able to induce apoptosis relative to the solvent control; in particular, (Z)-N-cyclohexyl-7-oxo-6-[4-(trifluoromethyl)phenyl]-1 1 H-3,10-dioxa-6-aza-1(4,1)-triazola-4(1,3),9(1,4)-dibenzenacyclotridecaphane-5-carboxamide (12 f) was the most potent in this regard (22.7 % of apoptosis). © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Discovery of 4-aryl-N-arylcarbonyl-2-aminothiazoles as Hec1/Nek2 inhibitors. Part I: optimization of in vitro potencies and pharmacokinetic properties.

PubMed

Lee, Ying-Shuan E; Chuang, Shih-Hsien; Huang, Lynn Y L; Lai, Chun-Liang; Lin, Yu-Hsiang; Yang, Ju-Ying; Liu, Chia-Wei; Yang, Sheng-chuan; Lin, Her-Sheng; Chang, Chia-chi; Lai, Jun-Yu; Jian, Pei-Shiou; Lam, King; Chang, Jia-Ming; Lau, Johnson Y N; Huang, Jiann-Jyh

2014-05-22

A series of 4-aryl-N-arylcarbonyl-2-aminothiazoles of scaffold 4 was designed and synthesized as Hec1/Nek2 inhibitors. Structural optimization of 4 led to compound 32 bearing C-4' 4-methoxyphenoxy and 4-(o-fluoropyridyl)carbonyl groups that showed low nanomolar in vitro antiproliferative activity (IC50: 16.3-42.7 nM), high intravenous AUC (64.9 μM·h, 2.0 mg/kg) in SD rats, and significant in vivo antitumor activity (T/C = 32%, 20 mg/kg, IV) in mice bearing human MDA-MB-231 xenografts. Cell responses resulting from Hec1/Nek2 inhibition were observed in cells treated with 32, including a reduced level of Hec1 coimmunoprecipitated with Nek2, degradation of Nek2, mitotic abnormalities, and apoptosis. Compound 32 showed selectivity toward cancer cells over normal phenotype cells and was inactive in a [(3)H]astemizole competitive binding assay for hERG liability screening. Therefore, 32 is as a good lead toward the discovery of a preclinical candidate targeting Hec1/Nek2 interaction.

Urea Derivatives of 2-Aryl-benzothiazol-5-amines: A New Class of Potential Drugs for Human African Trypanosomiasis.

PubMed

Patrick, Donald A; Gillespie, J Robert; McQueen, Joshua; Hulverson, Matthew A; Ranade, Ranae M; Creason, Sharon A; Herbst, Zackary M; Gelb, Michael H; Buckner, Frederick S; Tidwell, Richard R

2017-02-09

A previous publication from this lab (Patrick, et al. Bioorg. Med. Chem. 2016, 24 , 2451 - 2465 ) explored the antitrypanosomal activities of novel derivatives of 2-(2-benzamido)ethyl-4-phenylthiazole (1), which had been identified as a hit against Trypanosoma brucei, the causative agent of human African trypanosomiasis. While a number of these compounds, particularly the urea analogues, were quite potent, these molecules as a whole exhibited poor metabolic stability. The present work describes the synthesis of 65 new analogues arising from medicinal chemistry optimization at different sites on the molecule. The most promising compounds were the urea derivatives of 2-aryl-benzothiazol-5-amines. One such analogue, (S)-2-(3,4-difluorophenyl)-5-(3-fluoro-N-pyrrolidylamido)benzothiazole (57) was chosen for in vivo efficacy studies based upon in vitro activity, metabolic stability, and brain penetration. This compound attained 5/5 cures in murine models of both early and late stage human African trypanosomiasis, representing a new lead for the development of drugs to combat this neglected disease.

Sulfonamidation of Aryl and Heteroaryl Halides through Photosensitized Nickel Catalysis.

PubMed

Kim, Taehoon; McCarver, Stefan J; Lee, Chulbom; MacMillan, David W C

2018-03-19

Herein we report a highly efficient method for nickel-catalyzed C-N bond formation between sulfonamides and aryl electrophiles. This technology provides generic access to a broad range of N-aryl and N-heteroaryl sulfonamide motifs, which are widely represented in drug discovery. Initial mechanistic studies suggest an energy-transfer mechanism wherein C-N bond reductive elimination occurs from a triplet excited Ni II complex. Late-stage sulfonamidation in the synthesis of a pharmacologically relevant structure is also demonstrated. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

A New Route to Azafluoranthene Natural Products via Direct Arylation

PubMed Central

Ponnala, Shashikanth; Harding, Wayne W.

2013-01-01

Microwave-assisted direct arylation was successfully employed in the synthesis of azafluoranthene alkaloids for the first time. Direct arylation reactions on a diverse set of phenyltetrahydroisoquinolines produces the indeno[1,2,3-ij]isoquinoline nucleus en route to a high yielding azafluoranthene synthesis. The method was used as a key step in the efficient preparation of the natural products rufescine and triclisine. As demonstrated herein, this synthetic approach should be generally applicable to the preparation of natural and un-natural azafluoranthene alkaloids as well as “azafluoranthene-like” isoquinoline alkaloids. PMID:23503080

Selective Ether/Ester C–O Cleavage of an Acetylated Lignin Model via Tandem Catalysis

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

Lohr, Tracy L.; Li, Zhi; Marks, Tobin J.

2015-11-06

Lignin, a heterogeneous phenolic polymer which constitutes roughly 15 to 20 wt % of lignocellulosic biomass (cellulose, hemicellose, and lignin), represents one of the few renewable sources of aromatic monomers.(1) Current lignin depolymerization methodologies, including base-catalyzed,(2) acid-catalyzed,(3) metal-catalyzed,(4) ionic liquid (IL)-assisted,(5) and supercritical-fluid-assisted(2b, 6) approaches, typically afford low yields (~10–20% or less) of low molecular weight aromatics under relatively harsh reaction conditions (>300 °C).(7) Recent advances include using oxidized lignin and lignin models,(8) where oxidation of the Cα alcohol facilitates depolymerizaton, with aromatic monomer yields reaching up to 52% for aspen “hardwood” lignin.(9) The most common structural lignin motifs containmore » a β-O-4 aryl-ether linkage,(10) a primary alcohol in the γ skeletal position, and a secondary alcohol in the α position (Scheme 1). Our laboratory has previously demonstrated an effective strategy for thermodynamically leveraged etheric and esteric C–O bond hydrogenolysis using a tandem metal triflate + supported palladium catalytic system.(11) A homogeneous M(OTf)n catalyst mediates endothermic ether or near thermoneutral ester C–O bond scission (the reverse of hydroelementation), which is coupled to exothermic Pd-catalyzed hydrogenation of the resulting C=C unsaturation, driving the overall process downhill. We next asked whether this tandem system might be applicable to cleaving the β-O-4 aryl-ether bond in lignin and lignin models. The promising results of that investigation are communicated here.« less