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Sample records for alcohols structure-activity relationship

  1. Ecological Structure Activity Relationships

    EPA Science Inventory

    Ecological Structure Activity Relationships, v1.00a, February 2009
    ECOSAR (Ecological Structure Activity Relationships) is a personal computer software program that is used to estimate the toxicity of chemicals used in industry and discharged into water. The program predicts...

  2. Ecotoxicity quantitative structure-activity relationships for alcohol ethoxylate mixtures based on substance-specific toxicity predictions.

    PubMed

    Boeije, G M; Cano, M L; Marshall, S J; Belanger, S E; Van Compernolle, R; Dorn, P B; Gümbel, H; Toy, R; Wind, T

    2006-05-01

    Traditionally, ecotoxicity quantitative structure-activity relationships (QSARs) for alcohol ethoxylate (AE) surfactants have been developed by assigning the measured ecotoxicity for commercial products to the average structures (alkyl chain length and ethoxylate chain length) of these materials. Acute Daphnia magna toxicity tests for binary mixtures indicate that mixtures are more toxic than the individual AE substances corresponding with their average structures (due to the nonlinear relation of toxicity with structure). Consequently, the ecotoxicity value (expressed as effects concentration) attributed to the average structures that are used to develop the existing QSARs is expected to be too low. A new QSAR technique for complex substances, which interprets the mixture toxicity with regard to the "ethoxymers" distribution (i.e., the individual AE components) rather than the average structure, was developed. This new technique was then applied to develop new AE ecotoxicity QSARs for invertebrates, fish, and mesocosms. Despite the higher complexity, the fit and accuracy of the new QSARs are at least as good as those for the existing QSARs based on the same data set. As expected from typical ethoxymer distributions of commercial AEs, the new QSAR generally predicts less toxicity than the QSARs based on average structure. PMID:16256196

  3. MOLECULAR TOPOLOGY AND NARCOSIS - A QUANTITATIVE STRUCTURE-ACTIVITY RELATIONSHIP (QSAR) STUDY OF ALCOHOLS USING COMPLEMENTARY INFORMATION CONTENT (CIC)

    EPA Science Inventory

    A newly formulated information -theoretic topological index - complementary information content (CIC) - defined for the planar chemical graph of molecules is applied in the QSAR studies of congeneric series of alcohols. Results show that CIC can quantitatively predict the LC50 va...

  4. Mechanistic insight into aerobic alcohol oxidation using NOx-nitroxide catalysis based on catalyst structure-activity relationships.

    PubMed

    Shibuya, Masatoshi; Nagasawa, Shota; Osada, Yuji; Iwabuchi, Yoshiharu

    2014-11-01

    The mechanism of an NOx-assisted, nitroxide(nitroxyl radical)-catalyzed aerobic oxidation of alcohols was investigated using a set of sterically and electronically modified nitroxides (i.e., TEMPO, AZADO (1), 5-F-AZADO (2), 5,7-DiF-AZADO (3), 5-MeO-AZADO (4), 5,7-DiMeO-AZADO (5), oxa-AZADO (6), TsN-AZADO (7), and DiAZADO (8)). The motivation for the present study stemmed from our previous observation that the introduction of an F atom at a remote position from the nitroxyl radical moiety on the azaadamantane nucleus effectively enhanced the catalytic activity under typical NOx-mediated aerobic-oxidation conditions. The kinetic profiles of the azaadamantane-N-oxyl-[AZADO (1)-, 5-F-AZADO (2)-, and 5,7-DiF-AZADO (3)]-catalyzed aerobic oxidations were closely investigated, revealing that AZADO (1) showed a high initial reaction rate compared to 5-F-AZADO (2) and 5,7-DiF-AZADO (3); however, AZADO-catalyzed oxidation exhibited a marked slowdown, resulting in ∼90% conversion, whereas 5-F-AZADO-catalyzed oxidation smoothly reached completion without a marked slowdown. The reasons for the marked slowdown and the role of the fluoro group are discussed. Oxa-AZADO (6), TsN-AZADO (7), and DiAZADO (8) were designed and synthesized to confirm their comparable catalytic efficiency to that of 5-F-AZADO (2), providing supporting evidence for the electronic effect on the catalytic efficiency of the heteroatoms under NOx-assisted aerobic-oxidation conditions. PMID:25286356

  5. Peptide Bacteriocins--Structure Activity Relationships.

    PubMed

    Etayash, Hashem; Azmi, Sarfuddin; Dangeti, Ramana; Kaur, Kamaljit

    2015-01-01

    With the growing concerns in the scientific and health communities over increasing levels of antibiotic resistance, antimicrobial peptide bacteriocins have emerged as promising alternatives to conventional small molecule antibiotics. A substantial attention has recently focused on the utilization of bacteriocins in food preservation and health safety. Despite the fact that a large number of bacteriocins have been reported, only a few have been fully characterized and structurally elucidated. Since knowledge of the molecular structure is a key for understanding the mechanism of action and therapeutic effects of peptide, we centered our focus in this review on the structure-activity relationships of bacteriocins with a particular focus in seven bacteriocins, namely, nisin, microcin J25, microcin B17, microcin C, leucocin A, sakacin P, and pediocin PA-1. Significant structural changes responsible for the altered activity of the recent bacteriocin analogues are discussed here. PMID:26265354

  6. THE PRACTICE OF STRUCTURE ACTIVITY RELATIONSHIPS (SAR) IN TOXICOLOGY

    EPA Science Inventory

    Both qualitative and quantitative modeling methods relating chemical structure to biological activity, called structure-activity relationship analyses or SAR, are applied to the prediction and characterization of chemical toxicity. This minireview will discuss some generic issue...

  7. DEVELOPMENT OF STRUCTURE ACTIVITY RELATIONSHIPS FOR ASSESSING ECOLOGICAL RISKS

    EPA Science Inventory

    In the field of environmental toxicology, structure activity relationships (SARs) have developed as scientifically-credible tools for predicting the effects of chemicals when little or no empirical data are available.

  8. Structure-activity relationship of anthelmintic cyclooctadepsipeptides.

    PubMed

    Ohyama, Makoto; Okada, Yumiko; Takahashi, Masaaki; Sakanaka, Osamu; Matsumoto, Maki; Atsumi, Kunio

    2011-01-01

    The relationship between cyclooctadepsipeptides and their anthelmintic efficacy was examined by converting the natural products, PF1022A, PF1022E and PF1022H. Some analogues substituted at the para position of the phenyllactate moiety showed higher or equivalent activity against the parasitic nematode, Ascaridia galli in chicken when compared with the parent compounds. It is suggested that lipophilicity and the polar surface area, in addition to structural requirements of the derivatives, influenced the anthelmintic efficacy in vivo. PMID:21737929

  9. Quantitative structure-activity relationships for fluoroelastomer/chlorofluorocarbon systems

    SciTech Connect

    Paciorek, K.J.L.; Masuda, S.R.; Nakahara, J.H. ); Snyder, C.E. Jr.; Warner, W.M. )

    1991-12-01

    This paper reports on swell, tensile, and modulus data that were determined for a fluoroelastomer after exposure to a series of chlorofluorocarbon model fluids. Quantitative structure-activity relationships (QSAR) were developed for the swell as a function of the number of carbons and chlorines and for tensile strength as a function of carbon number and chlorine positions in the chlorofluorocarbons.

  10. Structure-Activity Relationships in Nitro-Aromatic Compounds

    NASA Astrophysics Data System (ADS)

    Vogt, R. A.; Rahman, S.; Crespo-Hernández, C. E.

    Many nitro-aromatic compounds show mutagenic and carcinogenic properties, posing a potential human health risk. Despite this potential health hazard, nitro-aromatic compounds continue to be emitted into ambient air from municipal incinerators, motor vehicles, and industrial power plants. As a result, understanding the structural and electronic factors that influence mutagenicity in nitro-aromatic compounds has been a long standing objective. Progress toward this goal has accelerated over the years, in large part due to the synergistic efforts among toxicology, computational chemistry, and statistical modeling of toxicological data. The concerted influence of several structural and electronic factors in nitro-aromatic compounds makes the development of structure-activity relationships (SARs) a paramount challenge. Mathematical models that include a regression analysis show promise in predicting the mutagenic activity of nitro-aromatic compounds as well as in prioritizing compounds for which experimental data should be pursued. A major challenge of the structure-activity models developed thus far is their failure to apply beyond a subset of nitro-aromatic compounds. Most quantitative structure-activity relationship papers point to statistics as the most important confirmation of the validity of a model. However, the experimental evidence shows the importance of the chemical knowledge in the process of generating models with reasonable applicability. This chapter will concisely summarize the structural and electronic factors that influence the mutagenicity in nitro-aromatic compounds and the recent efforts to use quantitative structure-activity relationships to predict those physicochemical properties.

  11. Structure-activity relationship of crustacean peptide hormones.

    PubMed

    Katayama, Hidekazu

    2016-04-01

    In crustaceans, various physiological events, such as molting, vitellogenesis, and sex differentiation, are regulated by peptide hormones. To understanding the functional sites of these hormones, many structure-activity relationship (SAR) studies have been published. In this review, the author focuses the SAR of crustacean hyperglycemic hormone-family peptides and androgenic gland hormone and describes the detailed results of our and other research groups. The future perspectives will be also discussed. PMID:26624010

  12. Partitioning and lipophilicity in quantitative structure-activity relationships.

    PubMed Central

    Dearden, J C

    1985-01-01

    The history of the relationship of biological activity to partition coefficient and related properties is briefly reviewed. The dominance of partition coefficient in quantitation of structure-activity relationships is emphasized, although the importance of other factors is also demonstrated. Various mathematical models of in vivo transport and binding are discussed; most of these involve partitioning as the primary mechanism of transport. The models describe observed quantitative structure-activity relationships (QSARs) well on the whole, confirming that partitioning is of key importance in in vivo behavior of a xenobiotic. The partition coefficient is shown to correlate with numerous other parameters representing bulk, such as molecular weight, volume and surface area, parachor and calculated indices such as molecular connectivity; this is especially so for apolar molecules, because for polar molecules lipophilicity factors into both bulk and polar or hydrogen bonding components. The relationship of partition coefficient to chromatographic parameters is discussed, and it is shown that such parameters, which are often readily obtainable experimentally, can successfully supplant partition coefficient in QSARs. The relationship of aqueous solubility with partition coefficient is examined in detail. Correlations are observed, even with solid compounds, and these can be used to predict solubility. The additive/constitutive nature of partition coefficient is discussed extensively, as are the available schemes for the calculation of partition coefficient. Finally the use of partition coefficient to provide structural information is considered. It is shown that partition coefficient can be a valuable structural tool, especially if the enthalpy and entropy of partitioning are available. PMID:3905374

  13. Penoxsulam--structure-activity relationships of triazolopyrimidine sulfonamides.

    PubMed

    Johnson, Timothy C; Martin, Timothy P; Mann, Richard K; Pobanz, Mark A

    2009-06-15

    The discovery of the sulfonamide herbicides, which inhibit the enzyme acetolactate synthase (ALS), has resulted in many investigations to exploit their herbicidal activity. One area which proved particularly productive was the N-aryltriazolo[1,5-c]pyrimidine sulfonamides, providing three commercial herbicides, cloransulam-methyl, diclosulam and florasulam. Additional structure-activity investigations by reversing the sulfonamide linkage resulted in the discovery of triazolopyrimidine sulfonamides with cereal crop selectivity and high levels of grass and broadleaf weed control. Research efforts to exploit these high levels of weed activity ultimately led to the discovery of penoxsulam, a new herbicide developed for grass, sedge and broadleaf weed control in rice. Synthetic efforts and structure-activity relationships leading to the discovery of penoxsulam will be discussed. PMID:19464188

  14. Structure-activity relationship of indoloquinoline analogs anti-MRSA.

    PubMed

    Zhao, Min; Kamada, Tomonori; Takeuchi, Aya; Nishioka, Hiromi; Kuroda, Teruo; Takeuchi, Yasuo

    2015-12-01

    Indolo[3,2-b]quinoline analogs (3a-3s), 4-(acridin-9-ylamino) phenol hydrochloride (4), benzofuro[3,2-b]quinoline (3t), indeno[1,2-b]quinolines (3u and 3v) have been synthesized. Those compounds were found to exhibit anti-bacterial activity towards Methicillin-resistant Staphylococcus aureus (anti-MRSA activity). Structure-activity relationship studies were conducted that indoloquinoline ring, benzofuroquinoline ring and 4-aminophenol group are essential structure for anti-MRSA activity. PMID:26522949

  15. STRUCTURE-ACTIVITY RELATIONSHIP STUIDES AND THEIR ROLE IN PREDICTING AND INVESTIGATING CHEMICAL TOXICITY

    EPA Science Inventory

    Structure-Activity Relationship Studies and their Role in Predicting and Investigating Chemical Toxicity

    Structure-activity relationships (SAR) represent attempts to generalize chemical information relative to biological activity for the twin purposes of generating insigh...

  16. CONSIDERATION OF REACTION INTERMEDIATES IN STRUCTURE-ACTIVITY RELATIONSHIPS: A KEY TO UNDERSTANDING AND PREDICTION

    EPA Science Inventory

    Consideration of Reaction Intermediates in Structure- Activity Relationships: A Key to Understanding and Prediction

    A structure-activity relationship (SAR) represents an empirical means for generalizing chemical information relative to biological activity, and is frequent...

  17. Autotaxin Structure Activity Relationships Revealed through Lysophosphatidylcholine Analogs

    PubMed Central

    North, E. Jeffrey; Osborne, Daniel A.; Bridson, Peter K.; Baker, Daniel L.; Parrill, Abby L.

    2009-01-01

    Autotaxin (ATX) catalyzes the hydrolysis of lysophosphatidylcholine (LPC) to form the bioactive lipid lysophosphatidic acid (LPA). LPA stimulates cell proliferation, cell survival, and cell migration and is involved in obesity, rheumatoid arthritis, neuropathic pain, atherosclerosis and various cancers, suggesting that ATX inhibitors have broad therapeutic potential. Product feedback inhibition of ATX by LPA has stimulated structure activity studies focused on LPA analogs. However, LPA displays mixed mode inhibition, indicating it can bind to both the enzyme and the enzyme-substrate complex. This suggests that LPA may not interact solely with the catalytic site. In this report we have prepared LPC analogs to help map out substrate structure activity relationships. The structural variances include length and unsaturation of the fatty tail, choline and polar linker presence, acyl versus ether linkage of the hydrocarbon chain, and methylene and nitrogen replacement of the choline oxygen. All LPC analogs were assayed in competition with the synthetic substrate, FS-3, to show the preference ATX has for each alteration. Choline presence and methylene replacement of the choline oxygen were detrimental to ATX recognition. These findings provide insights into the structure of the enzyme in the vicinity of the catalytic site as well as suggesting that ATX produces rate enhancement, at least in part, by substrate destabilization. PMID:19345587

  18. Synthesis and Structural Activity Relationship Study of Antitubercular Carboxamides

    PubMed Central

    Ugwu, D. I.; Ezema, B. E.; Eze, F. U.; Ugwuja, D. I.

    2014-01-01

    The unusual structure and chemical composition of the mycobacterial cell wall, the tedious duration of therapy, and resistance developed by the microorganism have made the recurrence of the disease multidrug resistance and extensive or extreme drug resistance. The prevalence of tuberculosis in synergy with HIV/AIDS epidemic augments the risk of developing the disease by 100-fold. The need to synthesize new drugs that will shorten the total duration of effective treatment and/or significantly reduce the dosage taken under DOTS supervision, improve on the treatment of multidrug-resistant tuberculosis which defies the treatment with isoniazid and rifampicin, and provide effective treatment for latent TB infections which is essential for eliminating tuberculosis prompted this review. In this review, we considered the synthesis and structure activity relationship study of carboxamide derivatives with antitubercular potential. PMID:25610646

  19. Structure-Activity Relationship of Fluoroquinolones Against K. pneumoniae

    NASA Astrophysics Data System (ADS)

    Li, Xiao-hong; Zhang, Rui-zhou; Cheng, Xin-lu; Yang, Xiang-dong

    2007-04-01

    The structure-activity relationship of fluoroquinolones, which show anti-K. pneumoniae activity, was studied by using principal component analysis (PCA) and hierarchical cluster analysis (HCA). The PCA results showed that the lowest unoccupied molecular orbital energy, energy difference between the highest occupied and the lowest unoccupied molecular orbital, dipole moment, net atomic charge on atom I, molecular polarizability, partition coefficient and molecular refractivity of these compounds are responsible for the separation between high-activity and low-activity groups. The HCA results were similar to those obtained with PCA. By using the chemometric results, four synthetic compounds were analyzed through PCA and HCA, and three of them are proposed as active molecules against K. pneumoniae which is consistent with the results of clinical experiments. The methodologies of PCA and HCA provide a reliable rule for classifying new fluoroquinolones with anti-K. pneumoniae activity.

  20. Structure-activity relationships of glutamate carboxypeptidase II (GCPII) inhibitors.

    PubMed

    Ferraris, D V; Shukla, K; Tsukamoto, T

    2012-01-01

    Glutamate carboxypeptidase II (GCPII, EC 3.4.17.21) is a zinc metallopeptidase that hydrolyzes N-acetylaspartylglutamate (NAAG) into N-acetylaspartate (NAA) and glutamate in the nervous system. Inhibition of GCPII has the potential to reduce extracellular glutamate and represents an opportune target for treating neurological disorders in which excess glutamate is considered pathogenic. Furthermore, GCPII was found to be identical to a tumor marker, prostate-specific membrane antigen (PSMA), and has drawn significant interest as a diagnostic and/or therapeutic target in oncology. Over the past 15 years, tremendous efforts have been made in the discovery of potent GCPII inhibitors, particularly those with phosphorus-, urea- and thiol-based zinc binding groups. In addition, significant progress has been made in understanding the three-dimensional structural characteristics of GCPII in complex with various ligands. The purpose of this review article is to analyze the structure-activity relationships (SAR) of GCPII inhibitors reported to date, which are classified on the basis of their zinc-binding group. SAR and crystallographic data are evaluated in detail for each of these series to highlight the future challenges and opportunities to identify clinically viable GCPII inhibitors. PMID:22304717

  1. Structure activity relationships to assess new chemicals under TSCA

    SciTech Connect

    Auletta, A.E.

    1990-12-31

    Under Section 5 of the Toxic Substances Control Act (TSCA), manufacturers must notify the US Environmental Protection Agency (EPA) 90 days before manufacturing, processing, or importing a new chemical substance. This is referred to as a premanufacture notice (PMN). The PMN must contain certain information including chemical identity, production volume, proposed uses, estimates of exposure and release, and any health or environmental test data that are available to the submitter. Because there is no explicit statutory authority that requires testing of new chemicals prior to their entry into the market, most PMNs are submitted with little or no data. As a result, EPA has developed special techniques for hazard assessment of PMN chemicals. These include (1) evaluation of available data on the chemical itself, (2) evaluation of data on analogues of the PMN, or evaluation of data on metabolites or analogues of metabolites of the PMN, (3) use of quantitative structure activity relationships (QSARs), and (4) knowledge and judgement of scientific assessors in the interpretation and integration of the information developed in the course of the assessment. This approach to evaluating potential hazards of new chemicals is used to identify those that are most in need of addition review of further testing. It should not be viewed as a replacement for testing. 4 tabs.

  2. Synthesis and structure-activity relationships of neuromuscular blocking agents.

    PubMed

    Tuba, Zoltan; Maho, Sandor; Vizi, E Sylvester

    2002-08-01

    The first use of neuromuscular blocking agents (muscle relaxants) in clinical practice (1942) revolutionised the practice of anaesthesia and started the modern era of surgery. Since 1942 introduction of tubocurarine (18) neuromuscular blocking agents have been used routinely to provide skeletal muscle relaxation during surgical procedures allowing access to body cavities without hindrance from voluntary or reflex muscle movement. After the introduction of tubocurarine and the depolarizing suxamethonium chloride (4) (1949) several nondepolarizing steroidal and nonsteroidal neuromuscular blocking agents with different onset time and duration of effect were introduced e.g. gallamine triethiodide (1) (1949), methocurine (2) (1949), alcuronium chloride (3) (1963), pancuronium bromide (9) (1968), vecuronium bromide (11) (1982), pipecuronium bromide (10) (1982), atracurium besylate (5) (1982), doxacurium chloride (6) (1991), mivacurium chloride (8) (1992), rocuronium bromide (12) (1994) cisatracurium besylate (7) (1996), and rapacuronium bromide (13) (2000). SZ 1677 (14) a steroid type nondepolarizing neuromuscular blocking agent under development (preclinical phase). This review article deals with a comprehensive survey of the progress in chemical, pharmacological and, in some respects, of clinical studies of neuromuscular blocking agents used in the clinical practice and under development, including the synthesis, structure elucidation, pharmacological actions, structure activity relationships studies of steroidal and nonsteroidal derivatives. PMID:12171561

  3. The structure-activity relationship in herbicidal monosubstituted sulfonylureas

    SciTech Connect

    Li, Zheng-Ming; Ma, Yi; Guddat, Luke; Cheng, Pei-Quan; Wang, Jian-Guo; Pang, Siew S; Dong, Yu-Hui; Lai, Cheng-Ming; Wang, Ling-Xiu; Jia, Guo-Feng; Li, Yong-Hong; Wang, Su-Hua; Liu, Jie; Zhao, Wei-Guang; Wang, Bao-Lei

    2012-05-24

    The herbicide sulfonylurea (SU) belongs to one of the most important class of herbicides worldwide. It is well known for its ecofriendly, extreme low toxicity towards mammals and ultralow dosage application. The original inventor, G Levitt, set out structure-activity relationship (SAR) guidelines for SU structural design to attain superhigh bioactivity. A new approach to SU molecular design has been developed. After the analysis of scores of SU products by X-ray diffraction methodology and after greenhouse herbicidal screening of 900 novel SU structures synthesized in the authors laboratory, it was found that several SU structures containing a monosubstituted pyrimidine moiety retain excellent herbicidal characteristics, which has led to partial revision of the Levitt guidelines. Among the novel SU molecules, monosulfuron and monosulfuron-ester have been developed into two new herbicides that have been officially approved for field application and applied in millet and wheat fields in China. A systematic structural study of the new substrate-target complex and the relative mode of action in comparison with conventional SU has been carried out. A new mode of action has been postulated.

  4. Development of structure-activity relationship for metal oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Liu, Rong; Zhang, Hai Yuan; Ji, Zhao Xia; Rallo, Robert; Xia, Tian; Chang, Chong Hyun; Nel, Andre; Cohen, Yoram

    2013-05-01

    Nanomaterial structure-activity relationships (nano-SARs) for metal oxide nanoparticles (NPs) toxicity were investigated using metrics based on dose-response analysis and consensus self-organizing map clustering. The NP cellular toxicity dataset included toxicity profiles consisting of seven different assays for human bronchial epithelial (BEAS-2B) and murine myeloid (RAW 264.7) cells, over a concentration range of 0.39-100 mg L-1 and exposure time up to 24 h, for twenty-four different metal oxide NPs. Various nano-SAR building models were evaluated, based on an initial pool of thirty NP descriptors. The conduction band energy and ionic index (often correlated with the hydration enthalpy) were identified as suitable NP descriptors that are consistent with suggested toxicity mechanisms for metal oxide NPs and metal ions. The best performing nano-SAR with the above two descriptors, built with support vector machine (SVM) model and of validated robustness, had a balanced classification accuracy of ~94%. An applicability domain for the present data was established with a reasonable confidence level of 80%. Given the potential role of nano-SARs in decision making, regarding the environmental impact of NPs, the class probabilities provided by the SVM nano-SAR enabled the construction of decision boundaries with respect to toxicity classification under different acceptance levels of false negative relative to false positive predictions.Nanomaterial structure-activity relationships (nano-SARs) for metal oxide nanoparticles (NPs) toxicity were investigated using metrics based on dose-response analysis and consensus self-organizing map clustering. The NP cellular toxicity dataset included toxicity profiles consisting of seven different assays for human bronchial epithelial (BEAS-2B) and murine myeloid (RAW 264.7) cells, over a concentration range of 0.39-100 mg L-1 and exposure time up to 24 h, for twenty-four different metal oxide NPs. Various nano-SAR building models were

  5. Quantitative structure-activity relationships for organophosphates binding to acetylcholinesterase.

    PubMed

    Ruark, Christopher D; Hack, C Eric; Robinson, Peter J; Anderson, Paul E; Gearhart, Jeffery M

    2013-02-01

    Organophosphates are a group of pesticides and chemical warfare nerve agents that inhibit acetylcholinesterase, the enzyme responsible for hydrolysis of the excitatory neurotransmitter acetylcholine. Numerous structural variants exist for this chemical class, and data regarding their toxicity can be difficult to obtain in a timely fashion. At the same time, their use as pesticides and military weapons is widespread, which presents a major concern and challenge in evaluating human toxicity. To address this concern, a quantitative structure-activity relationship (QSAR) was developed to predict pentavalent organophosphate oxon human acetylcholinesterase bimolecular rate constants. A database of 278 three-dimensional structures and their bimolecular rates was developed from 15 peer-reviewed publications. A database of simplified molecular input line entry notations and their respective acetylcholinesterase bimolecular rate constants are listed in Supplementary Material, Table I. The database was quite diverse, spanning 7 log units of activity. In order to describe their structure, 675 molecular descriptors were calculated using AMPAC 8.0 and CODESSA 2.7.10. Orthogonal projection to latent structures regression, bootstrap leave-random-many-out cross-validation and y-randomization were used to develop an externally validated consensus QSAR model. The domain of applicability was assessed by the William's plot. Six external compounds were outside the warning leverage indicating potential model extrapolation. A number of compounds had residuals >2 or <-2, indicating potential outliers or activity cliffs. The results show that the HOMO-LUMO energy gap contributed most significantly to the binding affinity. A mean training R (2) of 0.80, a mean test set R (2) of 0.76 and a consensus external test set R (2) of 0.66 were achieved using the QSAR. The training and external test set RMSE values were found to be 0.76 and 0.88. The results suggest that this QSAR model can be used in

  6. Sedative effects of inhaled essential oil components of traditional fragrance Pogostemon cablin leaves and their structure-activity relationships.

    PubMed

    Ito, Ken; Akahoshi, Yasuko; Ito, Michiho; Kaneko, Shuji

    2016-04-01

    Plants rich in essential oils, such as Pogostemon cablin (P. cablin; guǎng huò xiāng), have been used for aromas and as herbal medicines since ancient times because of their sedative effects. We investigated the sedative effects of hexane extract from P. cablin using locomotor activity in mice. Inhalation of P. cablin hexane extract exhibited significant sedative activity in a dose-dependent manner. In order to isolate the active constituents, the extract was fractionated and diacetone alcohol was identified as an active compound. Inhalation of diacetone alcohol significantly reduced murine locomotor activity in a dose-dependent manner, and this effect was not observed in olfaction-impaired mice. We examined the structure-activity relationship of diacetone alcohol and similar compounds. The ketone group at the two-position and number of carbons may play important roles in the sedative activity of diacetone alcohol. PMID:27114936

  7. Relationship between Alcohol Consumption and Alcohol Problems in Young Adults.

    ERIC Educational Resources Information Center

    Werch, Chudley E.; And Others

    1987-01-01

    Examined relationship among alcohol problems and alcohol consumption variables in 410 college students. Total alcohol-related problems, drinking and driving problems, and school problems increased significantly when subjects drank moderately. Physical illness problems increased during light drinking, while interpersonal and legal problems…

  8. Quantitative Structure--Activity Relationship Modeling of Rat Acute Toxicity by Oral Exposure

    EPA Science Inventory

    Background: Few Quantitative Structure-Activity Relationship (QSAR) studies have successfully modeled large, diverse rodent toxicity endpoints. Objective: In this study, a combinatorial QSAR approach has been employed for the creation of robust and predictive models of acute toxi...

  9. PREDICTING TOXICOLOGICAL ENDPOINTS OF CHEMICALS USING QUANTITATIVE STRUCTURE-ACTIVITY RELATIONSHIPS (QSARS)

    EPA Science Inventory

    Quantitative structure-activity relationships (QSARs) are being developed to predict the toxicological endpoints for untested chemicals similar in structure to chemicals that have known experimental toxicological data. Based on a very large number of predetermined descriptors, a...

  10. STRUCTURE-ACTIVITY RELATIONSHIPS FOR SCREENING ORGANIC CHEMICALS FOR POTENTIAL ECOTOXICITY EFFECTS

    EPA Science Inventory

    The paper presents structure-activity relationships (QSAR) for estimating the bioconcentration factor and acute toxicity of some classes of industrial chemicals using only the n-octanol/water partition coefficient (Log P) which is derived from chemical structure. The bioconcentra...

  11. Structure-activity relationships of aromatic diamines in the Ames Salmonella typhimurium assay. Part II.

    PubMed

    Kalopissis, G

    1992-09-01

    Structure-activity relationships in the case of aromatic monoamines, diversely substituted on the ring, using the mutagenic activity in the Ames test were studied in part I. This part II is based on the same general principles but applied to phenylene diamines (ortho, para and meta) diversely substituted on the ring. PMID:1381475

  12. STRUCTURE-ACTIVITY RELATIONSHIPS (SARS) AMONG MUTAGENS AND CARCINOGENS: A REVIEW

    EPA Science Inventory

    The review is an introduction to methods for evaluating structure-activity relationships (SARs), and, in particular, to those methods that have been applied to study mutagenicity and carcinogenicity. A brief history and some background material on the earliest attempts to correla...

  13. Total Synthesis and Structure-Activity Relationship of Glycoglycerolipids from Marine Organisms

    PubMed Central

    Zhang, Jun; Li, Chunxia; Yu, Guangli; Guan, Huashi

    2014-01-01

    Glycoglycerolipids occur widely in natural products, especially in the marine species. Glycoglycerolipids have been shown to possess a variety of bioactivities. This paper will review the different methodologies and strategies for the synthesis of biological glycoglycerolipids and their analogs for bioactivity assay. In addition, the bioactivities and structure-activity relationship of the glycoglycerolipids are also briefly outlined. PMID:24945415

  14. STRUCTURE-ACTIVITY RELATIONSHIPS AND ESTIMATION TECHNIQUES FOR BIODEGRADATION OF XENOBIOTICS

    EPA Science Inventory

    The Current status of structure-activity relationships for the biodegradation of xenobiotics is reviewed. esults are presented of a pilot study on biodegradation Constants obtained from Computer databases. ew analyses for a relatively large number of anilines and phenols are pres...

  15. DEVELOPMENT OF QUANTITATIVE STRUCTURE-ACTIVITY RELATIONSHIPS FOR PREDICTING BIODEGRADATION KINETICS

    EPA Science Inventory

    Results have been presented on the development of a structure-activity relationship for biodegradation using a group contribution approach. sing this approach, reported results of the kinetic rate constant agree within 20% with the predicted values. dditional compound studies are...

  16. QUANTITATIVE STRUCTURE-ACTIVITY RELATIONSHIPS FOR CHEMICAL REDUCTIONS OF ORGANIC CONTAMINANTS

    EPA Science Inventory

    Sufficient kinetic data on abiotic reduction reactions involving organic contaminants are now available that quantitative structure-activity relationships (QSARs) for these reactions can be developed. Over 50 QSARs have been reported, most in just the last few years, and they ar...

  17. Structure-guided unravelling: Phenolic hydroxyls contribute to reduction of acrylamide using multiplex quantitative structure-activity relationship modelling.

    PubMed

    Zhang, Yu; Huang, Mengmeng; Wang, Qiao; Cheng, Jun

    2016-05-15

    We reported a structure-activity relationship study on unravelling phenolic hydroxyls instead of alcoholic hydroxyls contribute to the reduction of acrylamide formation by flavonoids. The dose-dependent study shows a close correlation between the number of phenolic hydroxyls of flavonoids and their reduction effects. In view of positions of hydroxyls, the 3',4'(ortho)-dihydroxyls in B cycle, 3-hydroxyl or hydroxyls of 3-gallate in C cycle, and 5,7(meta)-dihydroxyls in A cycle of flavonoid structures play an important role in the reduction of acrylamide. Flavone C-glycosides are more effective at reducing the formation of acrylamide than flavone O-glycosides when sharing the same aglycone. The current multiplex quantitative structure-activity relationship (QSAR) equations effectively predict the inhibitory rates of acrylamide using selected chemometric parameters (R(2): 0.835-0.938). This pioneer study opens a broad understanding on the chemoprevention of acrylamide contaminants on a structural basis. PMID:26776000

  18. Structure-activity relationship study between baicalein and wogonin by spectrometry, molecular docking and microcalorimetry.

    PubMed

    Tu, Bao; Li, Rong-Rong; Liu, Zhi-Juan; Chen, Zhi-Feng; Ouyang, Yu; Hu, Yan-Jun

    2016-10-01

    Flavones (e.g. baicalein and wogonin) extensively used worldwide in food preparation and traditional medicine. In this study, a systematically comparative study of their structure-activity relationships (SAR) on their interaction with BSA, antioxidant activity and antibacterial activity has been carried out by spectrometry, molecular docking and microcalorimetry. Our results show that the skeleton structure of flavones, the number of hydroxyl groups, the type of functional group, conjugated system and the steric hindrance may be responsible for their different biological activity. These findings not only would lay a scientific foundation for discovering and designing flavones-based food and drug, may also help us to understanding the structure-activity relationship between flavones at the molecular level. PMID:27132840

  19. Exploring the structure-activity relationships of ABCC2 modulators using a screening approach.

    PubMed

    Wissel, Gloria; Kudryavtsev, Pavel; Ghemtio, Leo; Tammela, Päivi; Wipf, Peter; Yliperttula, Marjo; Finel, Moshe; Urtti, Arto; Kidron, Heidi; Xhaard, Henri

    2015-07-01

    ABCC2 is a transporter with key influence on liver and kidney pharmacokinetics. In order to explore the structure-activity relationships of compounds that modulate ABCC2, and by doing so gain insights into drug-drug interactions, we screened a library of 432 compounds for modulators of radiolabeled β-estradiol 17-(β-d-glucuronide) (EG) and fluorescent 5(6)-carboxy-2',7'-dichlorofluorescein transport (CDCF) in membrane vesicles. Following the primary screen at 80μM, dose-response curves were used to investigate in detail 86 compounds, identifying 16 low μM inhibitors and providing data about the structure-activity relationships in four series containing 19, 24, 10, and eight analogues. Measurements with the CDCF probe were consistently more robust than for the EG probe. Only one compound was clearly probe-selective with a 50-fold difference in the IC50s obtained by the two assays. We built 24 classification models using the SVM and fused-XY Kohonen methods, revealing molecular descriptors related to number of rings, solubility and lipophilicity as important to distinguish inhibitors from inactive compounds. This study is to the best of our knowledge the first to provide details about structure-activity relationships in ABCC2 modulation. PMID:25935289

  20. Structure-activity relationship investigations of leishmanicidal N-benzylcytisine derivatives.

    PubMed

    Turabekova, Malakhat A; Vinogradova, Valentina I; Werbovetz, Karl A; Capers, Jeffrey; Rasulev, Bakhtiyor F; Levkovich, Mikhail G; Rakhimov, Shukhrat B; Abdullaev, Nasrulla D

    2011-07-01

    In vitro leishmanicidal activity of 16 N-benzylcytisine derivatives has been evaluated using Leishmania donovani axenic amastigotes. In general, halogen (bromo-, chloro-) derivatives appeared to be more toxic against parasites than their parent compounds. Quantum-chemical calculations helped to recognize certain patterns in the structure of frontier orbitals related to bioactivity of compounds. Thus, the presence of halogen atom is shown to have a significant effect on both distribution and the energy of LUMOs thereby on potent activity that was also confirmed by Quantitative-Structure Activity Relationship (QSAR) analysis. Experimentally and theoretically observed structure-cytotoxicity relationships are described. PMID:21457471

  1. HomoSAR: bridging comparative protein modeling with quantitative structural activity relationship to design new peptides.

    PubMed

    Borkar, Mahesh R; Pissurlenkar, Raghuvir R S; Coutinho, Evans C

    2013-11-15

    Peptides play significant roles in the biological world. To optimize activity for a specific therapeutic target, peptide library synthesis is inevitable; which is a time consuming and expensive. Computational approaches provide a promising way to simply elucidate the structural basis in the design of new peptides. Earlier, we proposed a novel methodology termed HomoSAR to gain insight into the structure activity relationships underlying peptides. Based on an integrated approach, HomoSAR uses the principles of homology modeling in conjunction with the quantitative structural activity relationship formalism to predict and design new peptide sequences with the optimum activity. In the present study, we establish that the HomoSAR methodology can be universally applied to all classes of peptides irrespective of sequence length by studying HomoSAR on three peptide datasets viz., angiotensin-converting enzyme inhibitory peptides, CAMEL-s antibiotic peptides, and hAmphiphysin-1 SH3 domain binding peptides, using a set of descriptors related to the hydrophobic, steric, and electronic properties of the 20 natural amino acids. Models generated for all three datasets have statistically significant correlation coefficients (r(2)) and predictive r2 (r(pred)2) and cross validated coefficient ( q(LOO)2). The daintiness of this technique lies in its simplicity and ability to extract all the information contained in the peptides to elucidate the underlying structure activity relationships. The difficulties of correlating both sequence diversity and variation in length of the peptides with their biological activity can be addressed. The study has been able to identify the preferred or detrimental nature of amino acids at specific positions in the peptide sequences. PMID:24105965

  2. Uncoupling the Structure-Activity Relationships of β2 Adrenergic Receptor Ligands from Membrane Binding.

    PubMed

    Dickson, Callum J; Hornak, Viktor; Velez-Vega, Camilo; McKay, Daniel J J; Reilly, John; Sandham, David A; Shaw, Duncan; Fairhurst, Robin A; Charlton, Steven J; Sykes, David A; Pearlstein, Robert A; Duca, Jose S

    2016-06-23

    Ligand binding to membrane proteins may be significantly influenced by the interaction of ligands with the membrane. In particular, the microscopic ligand concentration within the membrane surface solvation layer may exceed that in bulk solvent, resulting in overestimation of the intrinsic protein-ligand binding contribution to the apparent/measured affinity. Using published binding data for a set of small molecules with the β2 adrenergic receptor, we demonstrate that deconvolution of membrane and protein binding contributions allows for improved structure-activity relationship analysis and structure-based drug design. Molecular dynamics simulations of ligand bound membrane protein complexes were used to validate binding poses, allowing analysis of key interactions and binding site solvation to develop structure-activity relationships of β2 ligand binding. The resulting relationships are consistent with intrinsic binding affinity (corrected for membrane interaction). The successful structure-based design of ligands targeting membrane proteins may require an assessment of membrane affinity to uncouple protein binding from membrane interactions. PMID:27239696

  3. Structure activity relationship study of curcumin analogues toward the amyloid-beta aggregation inhibitor.

    PubMed

    Endo, Hitoshi; Nikaido, Yuri; Nakadate, Mamiko; Ise, Satomi; Konno, Hiroyuki

    2014-12-15

    Inhibition of the amyloid β aggregation process could possibly prevent the onset of Alzheimer's disease. In this article, we report a structure-activity relationship study of curcumin analogues for anti amyloid β aggregation activity. Compound 7, the ideal amyloid β aggregation inhibitor in vitro among synthesized curcumin analogues, has not only potent anti amyloid β aggregation effects, but also water solubility more than 160 times that of curcumin. In addition, new approaches to improve water solubility of curcumin-type compounds are proposed. PMID:25467149

  4. Novel spiropyrazolone antitumor scaffold with potent activity: Design, synthesis and structure-activity relationship.

    PubMed

    Wu, Shanchao; Li, Yu; Xu, Guixia; Chen, Shuqiang; Zhang, Yongqiang; Liu, Na; Dong, Guoqiang; Miao, Chaoyu; Su, Hua; Zhang, Wannian; Sheng, Chunquan

    2016-06-10

    Phenotypic screening of high quality compound library is an effective strategy to discover novel bioactive molecules. Previously, we developed the divergent organocatalytic cascade approach to efficiently construct a focused library with scaffold diversity and successfully identified a novel spiropyrazolone antitumor scaffold. Herein, a series of spiropyrazolone derivatives were designed, synthesized and assayed. Most of them showed good in vitro antitumor activity with a broad spectrum. Preliminary structure-activity relationship for the substitutions and the stereo configuration were obtained. Compound 5k showed good antitumor activity and could effectively induce cancer cell apoptosis, which represents a good starting point for the development of novel antitumor agents. PMID:27016707

  5. Isothiocyanate synthetic analogs: biological activities, structure-activity relationships and synthetic strategies.

    PubMed

    Milelli, Andrea; Fimognari, Carmela; Ticchi, Nicole; Neviani, Paolo; Minarini, Anna; Tumiatti, Vincenzo

    2014-01-01

    Sulforaphane is a natural product that is constantly under biological investigation for its unique biological properties. This naturally occurring isothiocyanate (ITC) and its analogs are the main components of cruciferous vegetables, such as cauliflower, watercress, broccoli, cabbage, Brussels sprouts, widely used as chemopreventive agents. Due to their interesting biological profiles, natural ITCs have been exploited as starting point to develop new synthetic analogs. The present mini-review briefly highlights the most important biological actions of selected new synthetic ITCs focusing on their structure-activity relationships and related synthetic strategies. PMID:25373847

  6. Antibacterial structure-activity relationship studies of several tricyclic sulfur-containing flavonoids.

    PubMed

    Bahrin, Lucian G; Hopf, Henning; Jones, Peter G; Sarbu, Laura G; Babii, Cornelia; Mihai, Alina C; Stefan, Marius; Birsa, Lucian M

    2016-01-01

    A structure-activity relationship study concerning the antibacterial properties of several halogen-substituted tricyclic sulfur-containing flavonoids has been performed. The compounds have been synthesized by cyclocondensation of the corresponding 3-dithiocarbamic flavanones under acidic conditions. The influence of different halogen substituents on the antibacterial properties has been tested against Staphylococcus aureus and Escherichia coli. Amongst the N,N-dialkylamino-substituted flavonoids, those having an N,N-diethylamino moiety exhibited good to excellent antimicrobial properties against both pathogens. Fluorine-substituted flavonoids were found to be less active than those bearing other halogen atoms. PMID:27340492

  7. Cytochrome P450 Family 1 Inhibitors and Structure-Activity Relationships

    PubMed Central

    Liu, Jiawang; Sridhar, Jayalakshmi; Foroozesh, Maryam

    2014-01-01

    With the widespread use of O-alkoxyresorufin dealkylation assays since the 1990’s, thousands of inhibitors of cytochrome P450 family 1 enzymes (P450s 1A1, 1A2, and 1B1) have been identified and studied. Generally, planar polycyclic molecules such as polycyclic aromatic hydrocarbons, stilbenoids, and flavonoids are considered to potentially be effective inhibitors of these enzymes. However, the details of structure-activity relationships and selectivity of these inhibitors are still ambiguous. In this review, we thoroughly discuss the selectivity of many representative P450 family 1 inhibitors reported in the past 20 years through a meta-analysis. PMID:24287985

  8. Substrate Structure-Activity Relationships Guide Rational Engineering of Modular Polyketide Synthase Ketoreductases

    PubMed Central

    Bailey, Constance B.; Pasman, Marjolein E.; Keatinge-Clay, Adrian T.

    2015-01-01

    Modular polyketide synthase ketoreductases can set two chiral centers through a single reduction. To probe the basis of stereocontrol, a structure-activity relationship study was performed with three α-methyl, β-ketothioester substrates and four ketoreductases. Since interactions with the β-ketoacyl moiety were found to be most critical, residues implicated in contacting this moiety were mutated. Two mutations were sufficient to completely reverse the stereoselectivity of the model ketoreductase EryKR1, converting it from an enzyme that generates (2S,3R)-products into one that yields (2S,3S)-products. PMID:26568113

  9. Substrate structure-activity relationships guide rational engineering of modular polyketide synthase ketoreductases.

    PubMed

    Bailey, Constance B; Pasman, Marjolein E; Keatinge-Clay, Adrian T

    2016-01-14

    Modular polyketide synthase ketoreductases can set two chiral centers through a single reduction. To probe the basis of stereocontrol, a structure-activity relationship study was performed with three α-methyl, β-ketothioester substrates and four ketoreductases. Since interactions with the β-ketoacyl moiety were found to be most critical, residues implicated in contacting this moiety were mutated. Two mutations were sufficient to completely reverse the stereoselectivity of the model ketoreductase EryKR1, converting it from an enzyme that generates (2S,3R)-products into one that yields (2S,3S)-products. PMID:26568113

  10. Structure-activity relationship in high-performance iron-based electrocatalysts for oxygen reduction reaction

    NASA Astrophysics Data System (ADS)

    Song, Ping; Wang, Ying; Pan, Jing; Xu, Weilin; Zhuang, Lin

    2015-12-01

    A sustainable Iron (Fe), Nitrogen (N) co-doped high performance Fe-Nx/C electrocatalyst for oxygen reduction reaction (ORR) is synthesized simply based on nitric acid oxidation of cheap carbon black. The obtained optimal nonprecious metal electrocatalyst shows high ORR performance in both alkaline and acidic conditions and possesses appreciable performance/price ratio due to its low cost. Furthermore, the structure-activity relationship of different active sites on Fe-Nx/C is revealed systematically: Fe-N4/2-C > Fe4-N-C > N-C >> Fe4-C ≥ C, from both experimental and theoretical points of view.

  11. Structure-activity relationship study of EphB3 receptor tyrosine kinase inhibitors

    PubMed Central

    Qiao, Lixin; Choi, Sungwoon; Case, April; Gainer, Thomas G.; Seyb, Kathleen; Glicksman, Marcie A.; Lo, Donald C.; Stein, Ross L.; Cuny, Gregory D.

    2009-01-01

    A structure-activity relationship study for a 2-chloroanilide derivative of pyrazolo[1,5-a]pyridine revealed that increased EphB3 kinase inhibitory activity could be accomplished by retaining the 2-chloroanilide and introducing a phenyl or small electron donating substituents to the 5-position of the pyrazolo[1,5-a]pyridine. In addition, replacement of the pyrazolo[1,5-a]pyridine with imidazo[1,2-a]pyridine was well tolerated and resulted in enhanced mouse liver microsome stability. The structure-activity relationship for EphB3 inhibition of both heterocyclic series was similar. Kinase inhibitory activity was also demonstrated for representative analogs in cell culture. An analog (32, LDN-211904) was also profiled for inhibitory activity against a panel of two hundred and eighty eight kinases and found to be quite selective for tyrosine kinases. Overall, these studies provide useful molecular probes for examining the in vitro, cellular and potentially in vivo kinase-dependent function of EphB3 receptor. PMID:19783434

  12. Orthogonal chemistry for the synthesis of thiocoraline-triostin hybrids. Exploring their structure-activity relationship.

    PubMed

    Tulla-Puche, Judit; Auriemma, Sara; Falciani, Chiara; Albericio, Fernando

    2013-07-11

    The natural compounds triostin and thiocoraline are potent antitumor agents that act as DNA bisintercalators. From a pharmaceutical point of view, these compounds are highly attractive although they present a low pharmacokinetic profile, in part due to their low solubility. Synthetically, they represent a tour de force because no robust strategies have been developed to access a broad range of these bicyclic (depsi)peptides in a straightforward manner. Here we describe solid-phase strategies to synthesize new bisintercalators, such as thiocoraline-triostin hybrids, as well as analogues bearing soluble tags. Orthogonal protection schemes (up to five from: Fmoc, Boc Alloc, pNZ, o-NBS, and Troc), together with the right concourse of the coupling reagents (HOSu, HOBt, HOAt, Oxyma, EDC, DIPCDI, PyAOP, PyBOP, HATU, COMU), were crucial to establish the synthetic plan. In vitro studies and structure-activity relationships have been shown trends in the structure-activity relationship that will facilitate the design of new bisintercalators. PMID:23746132

  13. Synthesis, biological activities, and quantitative structure-activity relationship (QSAR) study of novel camptothecin analogues.

    PubMed

    Wu, Dan; Zhang, Shao-Yong; Liu, Ying-Qian; Wu, Xiao-Bing; Zhu, Gao-Xiang; Zhang, Yan; Wei, Wei; Liu, Huan-Xiang; Chen, An-Liang

    2015-01-01

    In continuation of our program aimed at the development of natural product-based pesticidal agents, three series of novel camptothecin derivatives were designed, synthesized, and evaluated for their biological activities against T. Cinnabarinus, B. brassicae, and B. xylophilus. All of the derivatives showed good-to-excellent activity against three insect species tested, with LC50 values ranging from 0.00761 to 0.35496 mmol/L. Remarkably, all of the compounds were more potent than CPT against T. Cinnabarinus, and compounds 4d and 4c displayed superior activity (LC50 0.00761 mmol/L and 0.00942 mmol/L, respectively) compared with CPT (LC50 0.19719 mmol/L) against T. Cinnabarinus. Based on the observed bioactivities, preliminary structure-activity relationship (SAR) correlations were also discussed. Furthermore, a three-dimensional quantitative structure-activity relationship (3D-QSAR) model using comparative molecular field analysis (CoMFA) was built. The model gave statistically significant results with the cross-validated q2 values of 0.580 and correlation coefficient r2 of 0.991 and  of 0.993. The QSAR analysis indicated that the size of the substituents play an important in the activity of 7-modified camptothecin derivatives. These findings will pave the way for further design, structural optimization, and development of camptothecin-derived compounds as pesticidal agents. PMID:25985362

  14. A categorical structure-activity relationship analysis of GPR119 ligands

    PubMed Central

    Kumar, Pritesh; Carrasquer, Carl A.; Carter, Arren; Song, Zhao-Hui; Cunningham, Albert R.

    2016-01-01

    The categorical structure-activity relationship (cat-SAR) expert system has been successfully used in the analysis of chemical compounds that cause toxicity. Herein we describe the use of this fragment-based approach to model ligands for the G protein-coupled receptor 119 (GPR119). Using compounds that are known GPR119 agonists and compounds that we have confirmed experimentally that are not GPR119 agonists, four distinct cat-SAR models were developed. Using a leave-one out validation routine, the best GPR119 model had an overall concordance of 99 %, a sensitivity of 99 %, and a specificity of 100 %. Our findings from the in-depth fragment analysis of several known GPR119 agonists were consistent with previously reported GPR119 structure-activity relationship (SAR) analyses. Overall, while our results indicate that we have developed a highly predictive cat-SAR model that can be potentially used to rapidly screen for prospective GPR119 ligands the applicability domain must be taken into consideration. Moreover, our study demonstrates for the first time, that the cat-SAR expert system can be used to model G protein-coupled receptor ligands, many of which are important therapeutic agents. PMID:25401513

  15. Toxicity challenges in environmental chemicals: Prediction of human plasma protein binding through quantitative structure-activity relationship (QSAR) models

    EPA Science Inventory

    The present study explores the merit of utilizing available pharmaceutical data to construct a quantitative structure-activity relationship (QSAR) for prediction of the fraction of a chemical unbound to plasma protein (Fub) in environmentally relevant compounds. Independent model...

  16. FISH ACUTE TOXICITY SYNDROMES: APPLICATION TO THE DEVELOPMENT OF MECHANISM-SPECIFIC QSARS (QUANTITATIVE STRUCTURE ACTIVITY RELATIONSHIPS)

    EPA Science Inventory

    Predictive models based on quantitative structure activity relationships (QSARs), are used as rapid screening tools to identify potentially hazardous chemicals. Several QSARs are now available that predict the acute toxicity of narcotic-industrial chemicals. Predictions for compo...

  17. THE USE OF STRUCTURE-ACTIVITY RELATIONSHIPS IN INTEGRATING THE CHEMISTRY AND TOXICOLOGY OF ENDOCRINE DISRUPTING CHEMICALS

    EPA Science Inventory

    Structure activity relationships (SARs) are based on the principle that structurally similar chemicals should have similar biological activity. SARs relate specifically-defined toxicological activity of chemicals to their molecular structure and physico-chemical properties. To de...

  18. ESTIMATION OF MICROBIAL REDUCTIVE TRANSFORMATION RATES FOR CHLORINATED BENZENES AND PHENOLS USING A QUANTITATIVE STRUCTURE-ACTIVITY RELATIONSHIP APPROACH

    EPA Science Inventory

    A set of literature data was used to derive several quantitative structure-activity relationships (QSARs) to predict the rate constants for the microbial reductive dehalogenation of chlorinated aromatics. Dechlorination rate constants for 25 chloroaromatics were corrected for th...

  19. Structure-activity relationships of polybiguanides with activity against human immunodeficiency virus type 1.

    PubMed

    Passic, Shendra R; Ferguson, Mary Lee; Catalone, Bradley J; Kish-Catalone, Tina; Kholodovych, Vladyslav; Zhu, Wei; Welsh, William; Rando, Robert; Howett, Mary K; Wigdahl, Brian; Labib, Mohamed; Krebs, Fred C

    2010-12-01

    Previous investigations showing that polydisperse biguanide (PDBG) molecules have activity against human immunodeficiency virus type 1 (HIV-1) also suggested a relationship between PDBG biologic activity and the lengths of hydrocarbon linkers surrounding the positively charged biguanide unit. To better define structure-activity relationships, PDBG molecules with select linker lengths were evaluated for cytotoxicity, anti-HIV-1 activity, and in vivo toxicity. Results of the in vitro experiments demonstrated that increases in linker length (and, therefore, increases in compound lipophilicity) were generally associated with increases in cytotoxicity and antiviral activity against HIV-1. However, a relationship between linker length asymmetry and in vitro therapeutic index (TI) suggested structural specificity in the mechanism of action against HIV-1. Polyethylene hexamethylene biguanide (PEHMB; biguanide units spaced between alternating ethylene and hexamethylene linkers) was found to have the highest in vitro TI (CC₅₀/IC₅₀) among the compounds examined. Recent improvements in PEHMB synthesis and purification have yielded preparations of PEHMB with in vitro TI values of 266 and 7000 against HIV-1 strains BaL and IIIB, respectively. The minimal toxicity of PEHMB relative to polyhexamethylene biguanide (PHMB; biguanide units alternating with hexamethylene linkers) in a murine model of cervicovaginal microbicide toxicity was consistent with considerable differences in cytotoxicity between PEHMB and PHMB observed during in vitro experiments. These structure-activity investigations increase our understanding of PDBG molecules as agents with activity against HIV-1 and provide the foundation for further preclinical studies of PEHMB and other biguanide-based compounds as antiviral and microbicidal agents. PMID:21106331

  20. Neurosteroid Structure-Activity Relationships for Functional Activation of Extrasynaptic δGABA(A) Receptors.

    PubMed

    Carver, Chase Matthew; Reddy, Doodipala Samba

    2016-04-01

    Synaptic GABAA receptors are primary mediators of rapid inhibition in the brain and play a key role in the pathophysiology of epilepsy and other neurologic disorders. The δ-subunit GABAA receptors are expressed extrasynaptically in the dentate gyrus and contribute to tonic inhibition, promoting network shunting as well as reducing seizure susceptibility. However, the neurosteroid structure-function relationship at δGABA(A) receptors within the native hippocampus neurons remains unclear. Here we report a structure-activity relationship for neurosteroid modulation of extrasynaptic GABAA receptor-mediated tonic inhibition in the murine dentate gyrus granule cells. We recorded neurosteroid allosteric potentiation of GABA as well as direct activation of tonic currents using a wide array of natural and synthetic neurosteroids. Our results shows that, for all neurosteroids, the C3α-OH group remains obligatory for extrasynaptic receptor functional activity, as C3β-OH epimers were inactive in activating tonic currents. Allopregnanolone and related pregnane analogs exhibited the highest potency and maximal efficacy in promoting tonic currents. Alterations at the C17 or C20 region of the neurosteroid molecule drastically altered the transduction kinetics of tonic current activation. The androstane analogs had the weakest modulatory response among the analogs tested. Neurosteroid potentiation of tonic currents was completely (approximately 95%) diminished in granule cells from δ-knockout mice, suggesting that δ-subunit receptors are essential for neurosteroid activity. The neurosteroid sensitivity of δGABA(A) receptors was confirmed at the systems level using a 6-Hz seizure test. A consensus neurosteroid pharmacophore model at extrasynaptic δGABA(A) receptors is proposed based on a structure-activity relationship for activation of tonic current and seizure protection. PMID:26857959

  1. Development of structure-activity relationship rules for predicting carcinogenic potential of chemicals.

    PubMed

    Woo, Y T; Lai, D Y; Argus, M F; Arcos, J C

    1995-09-01

    Since the inception of Section 5 (Premanufacturing/Premarketing Notification, PMN) of the Toxic Substances Control Act (TSCA), structure-activity relationship (SAR) analysis has been effectively used by U.S. Environmental Protection Agency's (EPA) Structure Activity Team (SAT) in the assessment of potential carcinogenic hazard of new chemicals for which test data are not available. To capture, systematize and codify the Agency's predictive expertise in order to make it more widely available to assessors outside the TSCA program, a cooperative project was initiated to develop a knowledge rule-based expert system to mimic the thinking and reasoning of the SAT. In this communication, we describe the overall structure of this expert system, discuss the scientific bases and principles of SAR analysis of chemical carcinogens used in the development of SAR knowledge rules, and delineate the major factors/rules useful for assessing the carcinogenic potential of fibers, polymers, metals/metalloids and several major classes of organic chemicals. An integrative approach using available short-term predictive tests and non-cancer toxicological data to supplement SAR analysis has also been described. PMID:7570659

  2. Discovery of KDM5A inhibitors: Homology modeling, virtual screening and structure-activity relationship analysis.

    PubMed

    Wu, Xiaoai; Fang, Zhen; Yang, Bo; Zhong, Lei; Yang, Qiuyuan; Zhang, Chunhui; Huang, Shenzhen; Xiang, Rong; Suzuki, Takayoshi; Li, Lin-Li; Yang, Sheng-Yong

    2016-05-01

    Herein we report the discovery of a series of new KDM5A inhibitors. A three-dimensional (3D) structure model of KDM5A jumonji domain was firstly established based on homology modeling. Molecular docking-based virtual screening was then performed against commercial chemical databases. A number of hit compounds were retrieved. Further structural optimization and structure-activity relationship (SAR) analysis were carried out to the most active hit compound, 9 (IC50: 2.3μM), which led to the discovery of several new KDM5A inhibitors. Among them, compound 15e is the most potent one with an IC50 value of 0.22μM against KDM5A. This compound showed good selectivity for KDM5A and considerable ability to suppress the demethylation of H3K4me3 in intact cells. Compound 15e could be taken as a good lead compound for further studies. PMID:27020306

  3. A quantitative structure-activity relationship approach for assessing toxicity of mixture of organic compounds.

    PubMed

    Chang, C M; Ou, Y H; Liu, T-C; Lu, S-Y; Wang, M-K

    2016-06-01

    Four types of reactivity indices were employed to construct quantitative structure-activity relationships for the assessment of toxicity of organic chemical mixtures. Results of analysis indicated that the maximum positive charge of the hydrogen atom and the inverse of the apolar surface area are the most important descriptors for the toxicity of mixture of benzene and its derivatives to Vibrio fischeri. The toxicity of mixture of aromatic compounds to green alga Scenedesmus obliquus is mainly affected by the electron flow and electrostatic interactions. The electron-acceptance chemical potential and the maximum positive charge of the hydrogen atom are found to be the most important descriptors for the joint toxicity of aromatic compounds. PMID:27426856

  4. Applications of genetic algorithms on the structure-activity relationship analysis of some cinnamamides.

    PubMed

    Hou, T J; Wang, J M; Liao, N; Xu, X J

    1999-01-01

    Quantitative structure-activity relationships (QSARs) for 35 cinnamamides were studied. By using a genetic algorithm (GA), a group of multiple regression models with high fitness scores was generated. From the statistical analyses of the descriptors used in the evolution procedure, the principal features affecting the anticonvulsant activity were found. The significant descriptors include the partition coefficient, the molar refraction, the Hammet sigma constant of the substituents on the benzene ring, and the formation energy of the molecules. It could be found that the steric complementarity and the hydrophobic interaction between the inhibitors and the receptor were very important to the biological activity, while the contribution of the electronic effect was not so obvious. Moreover, by construction of the spline models for these four principal descriptors, the effective range for each descriptor was identified. PMID:10529984

  5. Structure-Activity Relationship for the 4(3H)-Quinazolinone Antibacterials.

    PubMed

    Bouley, Renee; Ding, Derong; Peng, Zhihong; Bastian, Maria; Lastochkin, Elena; Song, Wei; Suckow, Mark A; Schroeder, Valerie A; Wolter, William R; Mobashery, Shahriar; Chang, Mayland

    2016-05-26

    We recently reported on the discovery of a novel antibacterial (2) with a 4(3H)-quinazolinone core. This discovery was made by in silico screening of 1.2 million compounds for binding to a penicillin-binding protein and the subsequent demonstration of antibacterial activity against Staphylococcus aureus. The first structure-activity relationship for this antibacterial scaffold is explored in this report with evaluation of 77 variants of the structural class. Eleven promising compounds were further evaluated for in vitro toxicity, pharmacokinetics, and efficacy in a mouse peritonitis model of infection, which led to the discovery of compound 27. This new quinazolinone has potent activity against methicillin-resistant (MRSA) strains, low clearance, oral bioavailability and shows efficacy in a mouse neutropenic thigh infection model. PMID:27088777

  6. Mechanisms of toxic action and structure-activity relationships for organochlorine and synthetic pyrethroid insecticides.

    PubMed Central

    Coats, J R

    1990-01-01

    The mechanisms and sites of action of organochlorine (DDT-types and chlorinated alicyclics) and synthetic pyrethroid insecticides are presented with discussion of symptoms, physiological effects, and selectivity. The structural requirements for toxicity are assessed, and structure-activity relationships are considered for each subclass. Lipophilicity is important for all the groups because it facilitates delivery of these neurotoxicants to the site of action in the nerve. Steric factors including molecular volume, shape, and isomeric configuration greatly influence toxicity. Electronic parameters also have been demonstrated to affect biological activity in some of the groups of insecticides, e.g., Hammett's sigma and Taft's sigma * as indicators of electronegativity. New synthetic pyrethroids continue to be developed, with varied structures and different physicochemical and biological properties. PMID:2176589

  7. Structure-activity relationships and in silico models of P-glycoprotein (ABCB1) inhibitors.

    PubMed

    Liu, Hongming; Ma, Zhiguo; Wu, Baojian

    2013-11-01

    1. The efflux pump p-glycoprotein (P-gp/ABCB1) has received enormous attention in drug (xenobiotic) disposition due to its role in modulation of the drug availability and in protection of sensitive organs. 2. P-gp mediated efflux is one of main mechanisms for multidrug resistance in cancer cells. A main approach to reverse the resistance and restore the drug efficacy is to use specific inhibitors of P-gp that suppress the efflux activity. 3. This review summarizes the binding capabilities of known chemical inhibitors based on the analyses of structure-activity relationships, and computational modeling of the inhibitors as well as the binding site of P-gp protein. 4. The molecular models will facilitate the design of lead inhibitors as drug candidates. Also, it helps scientists in early drug discovery phase to synthesize chemical series with better understanding of their P-gp binding liabilities. PMID:23617855

  8. Biosynthesis-driven structure-activity relationship study of premonensin-derivatives.

    PubMed

    Ismail-Ali, A; Fansa, E K; Pryk, N; Yahiaoui, S; Kushnir, S; Pflieger, M; Wittinghofer, A; Schulz, F

    2016-08-10

    The controlled derivatization of natural products is of great importance for their use in drug discovery. The ideally rapid generation of compound libraries for structure-activity relationship studies is of particular concern. We here use modified biosynthesis for the generation of such a library of reduced polyketides to interfere with the oncogenic KRas pathway. The polyketide is derivatized via side chain alteration, and variations in its redox pattern and in its backbone chain length through manipulation in the corresponding polyketide synthase. Structural and biophysical analyses revealed the nature of the interaction between the polyketides and KRas-interacting protein PDE6δ. Non-natural polyketides with low nanomolar affinity to PDE6δ were identified. PMID:27452503

  9. Quantitative structure-activity relationships of selective antagonists of glucagon receptor using QuaSAR descriptors.

    PubMed

    Manoj Kumar, Palanivelu; Karthikeyan, Chandrabose; Hari Narayana Moorthy, Narayana Subbiah; Trivedi, Piyush

    2006-11-01

    In the present paper, quantitative structure activity relationship (QSAR) approach was applied to understand the affinity and selectivity of a novel series of triaryl imidazole derivatives towards glucagon receptor. Statistically significant and highly predictive QSARs were derived for glucagon receptor inhibition by triaryl imidazoles using QuaSAR descriptors of molecular operating environment (MOE) employing computer-assisted multiple regression procedure. The generated QSAR models revealed that factors related to hydrophobicity, molecular shape and geometry predominantly influences glucagon receptor binding affinity of the triaryl imidazoles indicating the relevance of shape specific steric interactions between the molecule and the receptor. Further, QSAR models formulated for selective inhibition of glucagon receptor over p38 mitogen activated protein (MAP) kinase of the compounds in the series highlights that the same structural features, which influence the glucagon receptor affinity, also contribute to their selective inhibition. PMID:17077558

  10. The structure-activity relationships of L3MBTL3 inhibitors: flexibility of the dimer interface

    PubMed Central

    Camerino, Michelle A.; Zhong, Nan; Dong, Aiping; Dickson, Bradley M.; James, Lindsey I.; Baughman, Brandi M.; Norris, Jacqueline L.; Kireev, Dmitri B.; Janzen, William P.; Arrowsmith, Cheryl H.

    2013-01-01

    We recently reported the discovery of UNC1215, a potent and selective chemical probe for the L3MBTL3 methyllysine reader domain. In this article, we describe the development of structure-activity relationships (SAR) of a second series of potent L3MBTL3 antagonists which evolved from the structure of the chemical probe UNC1215. These compounds are selective for L3MBTL3 against a panel of methyllysine reader proteins, particularly the related MBT family proteins, L3MBTL1 and MBTD1. A co-crystal structure of L3MBTL3 and one of the most potent compounds suggests that the L3MBTL3 dimer rotates about the dimer interface to accommodate ligand binding. PMID:24466405

  11. Development of quantitative structure activity relationships for the binding affinity of methoxypyridinium cations for human acetylcholinesterase.

    PubMed

    Morrill, Jason A; Topczewski, Joseph J; Lodge, Alexander M; Yasapala, Nilanthi; Quinn, Daniel M

    2015-11-01

    Among the most toxic substances known are the organophosphorus (OP) compounds used as pesticides and chemical warfare agents. Owing to their high toxicity there is a number of efforts underway to develop effective therapies for OP agent exposure. To date all therapies in use treat inhibited acetylcholinesterase (AChE), but are ineffective for the treatment of inhibited AChE, which has undergone a subsequent hydrolysis process, referred to as aging. Toward developing a therapy for treating victims of OP intoxication in the aged state we have developed Quantitative Structure-Activity Relationships (QSARs) based on the AM1 semiempirical quantum mechanical method using the program, CODESSA (COmprehensive Descriptors for Structural and Statistical Analysis). Using this methodology we obtained a multiple correlation QSAR equation which gave R(2)=0.9359 for a random training set of 38 ligands and R(2)=0.9236 for prediction on a random test set of 9 ligands. PMID:26454505

  12. Amyloid-β probes: Review of structure-activity and brain-kinetics relationships.

    PubMed

    Eckroat, Todd J; Mayhoub, Abdelrahman S; Garneau-Tsodikova, Sylvie

    2013-01-01

    The number of people suffering from Alzheimer's disease (AD) is expected to increase dramatically in the coming years, placing a huge burden on society. Current treatments for AD leave much to be desired, and numerous research efforts around the globe are focused on developing improved therapeutics. In addition, current diagnostic tools for AD rely largely on subjective cognitive assessment rather than on identification of pathophysiological changes associated with disease onset and progression. These facts have led to numerous efforts to develop chemical probes to detect pathophysiological hallmarks of AD, such as amyloid-β plaques, for diagnosis and monitoring of therapeutic efficacy. This review provides a survey of chemical probes developed to date for AD with emphasis on synthetic methodologies and structure-activity relationships with regards to affinity for target and brain kinetics. Several probes discussed herein show particularly promising results and will be of immense value moving forward in the fight against AD. PMID:23766818

  13. In vivo structure-activity relationship studies support allosteric targeting of a dual specificity phosphatase.

    PubMed

    Korotchenko, Vasiliy N; Saydmohammed, Manush; Vollmer, Laura L; Bakan, Ahmet; Sheetz, Kyle; Debiec, Karl T; Greene, Kristina A; Agliori, Christine S; Bahar, Ivet; Day, Billy W; Vogt, Andreas; Tsang, Michael

    2014-07-01

    Dual specificity phosphatase 6 (DUSP6) functions as a feedback attenuator of fibroblast growth factor signaling during development. In vitro high throughput chemical screening attempts to discover DUSP6 inhibitors have yielded limited success. However, in vivo whole-organism screens of zebrafish identified compound 1 (BCI) as an allosteric inhibitor of DUSP6. Here we designed and synthesized a panel of analogues to define the structure-activity relationship (SAR) of DUSP6 inhibition. In vivo high-content analysis in transgenic zebrafish, coupled with cell-based chemical complementation assays, identified structural features of the pharmacophore of 1 that were essential for biological activity. In vitro assays of DUSP hyperactivation corroborated the results from in vivo and cellular SAR. The results reinforce the notion that DUSPs are druggable through allosteric mechanisms and illustrate the utility of zebrafish as a model organism for in vivo SAR analyses. PMID:24909879

  14. Synthesis and Structure Activity Relationship of 3-Hydroxypyridin-2-thione Based Histone Deacetylase Inhibitors

    PubMed Central

    Sodji, Quaovi H.; Patil, Vishal; Kornacki, James R.; Mrksich, Milan; Oyelere, Adegboyega K.

    2014-01-01

    We have previously identified 3-hydroxypyridin-2-thione (3HPT) as a novel zinc binding group for histone deacetylase (HDAC) inhibition. Early structure activity relationship (SAR) studies led to various small molecules possessing selective inhibitory activity against HDAC6 or HDAC8 but are devoid of HDAC1 inhibition. To further delineate the depth of the SAR of 3HPT-derived HDAC inhibitors (HDACi), we have extended the SAR studies to include the linker region and the surface recognition group to optimize the HDAC inhibition. The current efforts resulted in the identification of two lead compounds 10d and 14e with potent HDAC6 and HDAC8 activities, but that are inactive against HDAC1. These new HDACi possess anti-cancer activities against various cancer cell lines including Jurkat J-γ1 against which SAHA and the previously disclosed 3HPT-derived HDACi were inactive. PMID:24304348

  15. New structure-activity relationships of N-acetamide substituted pyrazolopyrimidines as pharmacological ligands of TSPO.

    PubMed

    Li, Jun; Schulte, Michael L; Nickels, Michael L; Manning, H Charles

    2016-08-01

    Translocator protein (TSPO) represents an attractive target for molecular imaging and therapy due to its prevalence and critical roles played in oncology and other pathologies. Based upon our previously optimized pyrazolopyrimidine scaffold, we elucidated new structure activity relationships related to N,N-disubstitutions of the terminal acetamide on pyrazolopyrimidines and further explored the impacts of these substituents on lipophilicity and plasma protein binding. Several novel chemical probes reported here exhibited significantly increased binding affinity, suitable lipophilicity and protein binding compared with contemporary TSPO ligands. We illustrate that N,N-acetamide disubstitution affords opportunities to introduce diverse chemical moieties distal to the central pyrazolopyrimidine core, without sacrificing TSPO affinity. We anticipate that further exploration of N-acetamide substitutions may yield additional TSPO ligands capable of furthering the field of precision medicine. PMID:27353534

  16. Structure-activity relationships of furazano[3,4-b]pyrazines as mitochondrial uncouplers.

    PubMed

    Kenwood, Brandon M; Calderone, Joseph A; Taddeo, Evan P; Hoehn, Kyle L; Santos, Webster L

    2015-11-01

    Chemical mitochondrial uncouplers are lipophilic weak acids that transport protons into the mitochondrial matrix via a pathway that is independent of ATP synthase, thereby uncoupling nutrient oxidation from ATP production. These uncouplers have potential for the treatment of diseases such as obesity, Parkinson's disease, and aging. We have previously identified a novel mitochondrial protonophore, named BAM15, which stimulates mitochondrial respiration across a broad dosing range compared to carbonyl cyanide p-trifluoromethoxyphenylhydrazone (FCCP). Herein, we report our investigations on the structure-activity relationship profile of BAM15. Our studies demonstrate the importance of the furazan, pyrazine, and aniline rings as well as pKa in maintaining its effective protonophore activity. PMID:26119501

  17. Antimalarial benzoheterocyclic 4-aminoquinolines: Structure-activity relationship, in vivo evaluation, mechanistic and bioactivation studies.

    PubMed

    Ongarora, Dennis S B; Strydom, Natasha; Wicht, Kathryn; Njoroge, Mathew; Wiesner, Lubbe; Egan, Timothy J; Wittlin, Sergio; Jurva, Ulrik; Masimirembwa, Collen M; Chibale, Kelly

    2015-09-01

    A novel class of benzoheterocyclic analogues of amodiaquine designed to avoid toxic reactive metabolite formation was synthesized and evaluated for antiplasmodial activity against K1 (multidrug resistant) and NF54 (sensitive) strains of the malaria parasite Plasmodium falciparum. Structure-activity relationship studies led to the identification of highly promising analogues, the most potent of which had IC50s in the nanomolar range against both strains. The compounds further demonstrated good in vitro microsomal metabolic stability while those subjected to in vivo pharmacokinetic studies had desirable pharmacokinetic profiles. In vivo antimalarial efficacy in Plasmodium berghei infected mice was evaluated for four compounds, all of which showed good activity following oral administration. In particular, compound 19 completely cured treated mice at a low multiple dose of 4×10mg/kg. Mechanistic and bioactivation studies suggest hemozoin formation inhibition and a low likelihood of forming quinone-imine reactive metabolites, respectively. PMID:26264839

  18. Structure activity relationships of 4-hydroxy-2-pyridones: A novel class of antituberculosis agents.

    PubMed

    Ng, Pearly Shuyi; Manjunatha, Ujjini H; Rao, Srinivasa P S; Camacho, Luis R; Ma, Ngai Ling; Herve, Maxime; Noble, Christian G; Goh, Anne; Peukert, Stefan; Diagana, Thierry T; Smith, Paul W; Kondreddi, Ravinder Reddy

    2015-12-01

    Pyridone 1 was identified from a high-throughput cell-based phenotypic screen against Mycobacterium tuberculosis (Mtb) including multi-drug resistant tuberculosis (MDR-TB) as a novel anti-TB agent and subsequently optimized series using cell-based Mtb assay. Preliminary structure activity relationship on the isobutyl group with higher cycloalkyl groups at 6-position of pyridone ring has enabled us to significant improvement of potency against Mtb. The lead compound 30j, a dimethylcyclohexyl group on the 6-position of the pyridone, displayed desirable in vitro potency against both drug sensitive and multi-drug resistant TB clinical isolates. In addition, 30j displayed favorable oral pharmacokinetic properties and demonstrated in vivo efficacy in mouse model. These results emphasize the importance of 4-hydroxy-2-pyridones as a new chemotype and further optimization of properties to treat MDR-TB. PMID:26544629

  19. Synthesis, Structure-Activity Relationship, and Mechanistic Investigation of Lithocholic Acid Amphiphiles for Colon Cancer Therapy

    PubMed Central

    Bhargava, Priyanshu; Singh, Ashima; Motiani, Rajender K.; Shyam, Radhey; Sreekanth, Vedagopuram; Sengupta, Sagar; Bajaj, Avinash

    2014-01-01

    We report a structure-activity relationship of lithocholic acid amphiphiles for their anticancer activities against colon cancer. We synthesized ten cationic amphiphiles differing in nature of cationic charged head groups using lithocholic acid. We observed that anticancer activities of these amphiphiles against colon cancer cell lines are contingent on nature of charged head group. Lithocholic acid based amphiphile possessing piperidine head group (LCA-PIP1) is ~10 times more cytotoxic as compared to its precursor. Biochemical studies revealed that enhanced activity of LCA-PIP1 as compared to lithocholic acid is due to greater activation of apoptosis.LCA-PIP1 induces sub G0 arrest and causes cleavage of caspases. A single dose of lithocholic acid-piperidine derivative is enough to reduce the tumor burden by 75% in tumor xenograft model. PMID:25685308

  20. Synthesis, evaluation and structure-activity relationship of new 3-carboxamide coumarins as FXIIa inhibitors.

    PubMed

    Bouckaert, Charlotte; Serra, Silvia; Rondelet, Grégoire; Dolušić, Eduard; Wouters, Johan; Dogné, Jean-Michel; Frédérick, Raphaël; Pochet, Lionel

    2016-03-01

    Inhibitors of the coagulation factor XIIa (FXIIa) are attractive to detail the roles of this protease in hemostasis and thrombosis, to suppress artifact due to contact pathway activation in blood coagulation assays, and they are promising as antithrombotic therapy. The 3-carboxamide coumarins have been previously described as small-molecular-weight FXIIa inhibitors. In this study, we report a structure-activity relationship (SAR) study around this scaffold with the aim to discover new selective FXIIa inhibitors with an improved physico-chemical profile. To better understand these SAR, docking experiments were undertaken. For this purpose, we built an original hybrid model of FXIIa. This model has the advantage to gather the best features from the recently published crystal structure of FXIIa in its zymogen form and a more classical homology model. Results with the hybrid model are encouraging as they help understanding the activity and selectivity of our best compounds. PMID:26827162

  1. Quantitative structure-activity relationship of antifungal activity of rosin derivatives.

    PubMed

    Wang, Hui; Nguyen, Thi Thanh Hien; Li, Shujun; Liang, Tao; Zhang, Yuanyuan; Li, Jian

    2015-01-15

    To develop new rosin-based wood preservatives with good antifungal activity, 24 rosin derivatives were synthesized, bioassay tested with Trametes versicolor and Gloeophyllum trabeum, and subjected to analysis of their quantitative structure-activity relationships (QSAR). A QSAR analysis using Ampac 9.2.1 and Codessa 2.7.16 software built two QSAR models of antifungal ratio for T. versicolor and G. trabeum with values of R(2)=0.9740 and 0.9692, respectively. Based on the models, tri-N-(3-hydroabietoxy-2-hydroxy) propyl-triethyl ammonium chloride was designed and the bioassay test result proved its better inhibitory effect against the two selected fungi as expected. PMID:25466709

  2. Quantitative structure-activity relationships for cellular uptake of surface-modified nanoparticles.

    PubMed

    Liu, Rong; Rallo, Robert; Bilal, Muhammad; Cohen, Yoram

    2015-01-01

    Quantitative structure-activity relationships (QSARs) were developed, for cellular uptake of nanoparticles (NPs) of the same iron oxide core but with different surface-modifying organic molecules, based on linear and non-linear (epsilon support vector regression (ε-SVR)). A linear QSAR provided high prediction accuracy of R2=0.751 (coefficient of determination) using 11 descriptors selected from an initial pool of 184 descriptors calculated for the NP surfacemodifying molecules, while a ε-SVR based QSAR with only 6 descriptors improved prediction accuracy to R2=0.806. The linear and ε-SVR based QSARs both demonstrated good robustness and well spanned applicability domains. It is suggested that the approach of evaluating pertinent descriptors and their significance, via QSAR analysis, to cellular NP uptake could support planning and interpretation of toxicity studies as well as provide guidance for the tailor-design NPs with respect to targeted cellular uptake for various applications. PMID:25747434

  3. Structure-Activity Relationships of Retro-dihydrochalcones Isolated from Tacca sp

    PubMed Central

    Peng, Jiangnan; Risinger, April L.; Da, Chenxiao; Fest, Gary A.; Kellogg, Glen E.; Mooberry, Susan L.

    2014-01-01

    Several biologically active compounds have been identified from Tacca species, including glycosides, diarylheptanoids, saponins, withanolides, and the taccalonolide class of microtubule stabilizers. More recently, two cytotoxic retro-dihydrochalcones named evelynin A (7) and taccabulin A (6) were isolated and their biological activities characterized, including the finding that taccabulin has microtubule destabilizing effects. Here we describe the identification and characterization of five new retro-chalcones, named taccabulins B – E (1–4) and evelynin B (5) from Tacca sp. extracts. Their structures were determined using 1D and 2D NMR as well as mass spectroscopic data and modeled into the colchicine binding site of tubulin. The antiproliferative and microtubule effects of each compound were determined experimentally and found to be well correlated with modeling studies. The isolation and biological characterization of several retro-dihydrochalcones facilitated preliminary structure-activity relationships for this compound class concerning its antiproliferative and microtubule depolymerizing activities. PMID:24303844

  4. Monitoring the Progression of Structure-Activity Relationship Information during Lead Optimization.

    PubMed

    Shanmugasundaram, Veerabahu; Zhang, Liying; Kayastha, Shilva; de la Vega de León, Antonio; Dimova, Dilyana; Bajorath, Jürgen

    2016-05-12

    Lead optimization (LO) in medicinal chemistry is largely driven by hypotheses and depends on the ingenuity, experience, and intuition of medicinal chemists, focusing on the key question of which compound should be made next. It is essentially impossible to predict whether an LO project might ultimately be successful, and it is also very difficult to estimate when a sufficient number of compounds has been evaluated to judge the odds of a project. Given the subjective nature of LO decisions and the inherent optimism of project teams, very few attempts have been made to systematically evaluate project progression. Herein, we introduce a computational framework to follow the evolution of structure-activity relationship (SAR) information over a time course. The approach is based on the use of SAR matrix data structures as a diagnostic tool and enables graphical analysis of SAR redundancy and project progression. This framework should help the process of making decisions in close-in analogue work. PMID:26569348

  5. Synthesis, Antifungal Activity, and Structure Activity Relationships of Coruscanone A Analogs

    PubMed Central

    Babu, K. Suresh; Li, Xing-Cong; Jacob, Melissa R.; Zhang, Qifeng; Khan, Shabana I.; Ferreira, Daneel; Clark, Alice M.

    2008-01-01

    Coruscanone A, a plant derived cyclopentenedione derivative, showed potent in vitro antifungal activity against Candida albicans and Cryptococcus neoformans, comparable to amphotericin B and fluconazole. A series of analogs have been synthesized by modification of the cyclopentenedione ring, the enolic methoxy functionality, and the side chain styryl moiety of this natural product lead. A structurally close 1,4-benzoquinone analog was also prepared. All the compounds were examined for their in vitro activity against major opportunistic fungal pathogens including C. albicans, C. neoformans and Aspergillus fumigatus, and fluconazole-resistant C. albicans strains, with several analogs demonstrating potent antifungal activity. Structure activity relationship studies indicate that the 2-methoxymethylene-cyclopent-4-ene-1,3-dione structural moiety is the pharmacophore responsible for the antifungal activity of this class of compounds, while the side chain styryl-like moiety plays an important complementary role, presumably contributing to target binding. PMID:17181171

  6. Structure-Activity Relationships of Novel Tryptamine-Based Inhibitors of Bacterial Transglycosylase.

    PubMed

    Sosič, Izidor; Anderluh, Marko; Sova, Matej; Gobec, Martina; Mlinarič Raščan, Irena; Derouaux, Adeline; Amoroso, Ana; Terrak, Mohammed; Breukink, Eefjan; Gobec, Stanislav

    2015-12-24

    Penicillin-binding proteins represent well-established, validated, and still very promising targets for the design and development of new antibacterial agents. The transglycosylase domain of penicillin-binding proteins is especially important, as it catalyzes polymerization of glycan chains, using the peptidoglycan precursor lipid II as a substrate. On the basis of the previous discovery of a noncovalent small-molecule inhibitor of transglycosylase activity, we systematically explored the structure-activity relationships of these tryptamine-based inhibitors. The main aim was to reduce the nonspecific cytotoxic properties of the initial hit compound and concurrently to retain the mode of its inhibition. A focused library of tryptamine-based compounds was synthesized, characterized, and evaluated biochemically. The results presented here show the successful reduction of the nonspecific cytotoxicity, and the retention of the inhibition of transglycosylase enzymatic activity, as well as the ability of these compounds to bind to lipid II and to have antibacterial actions. PMID:26588190

  7. Defensive sesquiterpenes from Senecio candidans and S. magellanicus, and their structure-activity relationships.

    PubMed

    Reina, Matías; Santana, Omar; Domínguez, Dulce M; Villarroel, Luis; Fajardo, Víctor; Rodríguez, Matías L; González-Coloma, Azucena

    2012-03-01

    Eleven eremophilanolides, 1-3 and 6-13, and two eremophilanes, 24 and 25, were isolated from Senecio candidans and S. magellanicus from the Magallanes Region (Chile). Compounds 2, 3, 9, and 10 have not been previously reported as natural products. Their structures were established by NMR spectroscopic analysis and chemical transformations. The X-ray analysis of compounds 11, 13, and 17 were also performed. Different semisynthetic analogs from eremophilanolide 11 were generated to carry out a structure-activity relationship study. Their possible plant defensive role was tested against herbivorous insects (Spodoptera littoralis, Rhopalosiphum padi, and Myzus persicae) and plants (Lactuca sativa). Additionally, their effects on insect (Sf9) and mammalian (CHO) cell lines were tested. PMID:22422530

  8. Indolo[3,2-b]quinolines: Synthesis, Biological Evaluation and Structure Activity-Relationships

    PubMed Central

    Kumar, Eyunni V.K. Suresh; Etukala, Jagan R.; Ablordeppey, Seth Y.

    2013-01-01

    The tetracyclic indolo[3,2-b]quinoline ring system constitutes an important structural moiety in natural products exhibiting numerous biological activities. In particular, indolo [3, 2-b]quinoline, commonly known as linear quindo-line is of particular interest, because of its rigid structure and scope of derivatization. Although the core linear quindoline skeleton shows little or no activity in several biological systems, introduction of a methyl group on the N-5 atom leading to cryptolepine induces remarkable activity against a broad spectrum of biological targets. A number of analogs of quindoline and cryptolepine have been synthesized, incorporating various functional groups on the core quindoline skeleton leading to improved biological activities. In this review, we describe various synthetic methodologies leading to the quindoline scaffold, the biological activities and the structure activity relationships (SAR) of quindoline derivatives toward different disease states to give a better picture of the importance of this moiety in medicinal chemistry. PMID:18537709

  9. Bioisosterism of urea-based GCPII inhibitors. Synthesis and structure activity relationship studies

    SciTech Connect

    Wang, Haofan; Byun, Youngjoo; Barinka, Cyril; Pullambhatla, Mrudula; Bhang, Hyo-eun C; Fox, James J; Lubkowski, Jacek; Mease, Ronnie C; Pomper, Martin G

    2010-10-28

    We report a strategy based on bioisosterism to improve the physicochemical properties of existing hydrophilic, urea-based GCPII inhibitors. Comprehensive structure-activity relationship studies of the P1prime site of ZJ-43- and DCIBzL-based compounds identified several glutamate-free inhibitors with Ki values below 20 nM. Among them, compound 32d (Ki = 11 nM) exhibited selective uptake in GCPII-expressing tumors by SPECT-CT imaging in mice. A novel conformational change of amino acids in the S1prime pharmacophore pocket was observed in the X-ray crystal structure of GCPII complexed with 32d.

  10. Olfactory sensitivity and odor structure-activity relationships for aliphatic ketones in CD-1 mice.

    PubMed

    Laska, Matthias

    2014-06-01

    Using a conditioning paradigm, the olfactory sensitivity of CD-1 mice for a homologous series of aliphatic 2-ketones (2-butanone to 2-nonanone) and several of their isomeric forms was investigated. With all 11 odorants, the animals significantly discriminated concentrations as low as 0.01 ppm (parts per million) from the solvent, and with two odorants (2-octanone and 5-nonanone), the best-scoring animals even detected concentrations as low as 3 ppt (parts per trillion). Analysis of odor structure-activity relationships showed that the correlation between olfactory detection thresholds of the mice for the 2-ketones and carbon chain length can best be described as a U-shaped function with the lowest threshold values at 2-octanone. Similarly, the correlation between olfactory sensitivity and carbon chain length of symmetrical ketones (3-pentanone to 6-undecanone) can best be described as a U-shaped function. In contrast, no significant correlation was found between olfactory detection thresholds of the mice and position of the functional carbonyl group attached to a C7 backbone. A comparison between the olfactory detection thresholds obtained here with those obtained in earlier studies suggests that mice are significantly more sensitive for 2-ketones than for n-carboxylic acids of the same carbon chain length. Across-species comparisons suggest that mice are significantly more sensitive for aliphatic ketones than squirrel monkeys and pigtail macaques, whereas the ranges of human olfactory detection threshold values overlap with those of the mice with seven of the 11 ketones tested. Further comparisons suggest that odor structure-activity relationships are both substance class and species specific. PMID:24621664

  11. Novel 3-hydroxy-4-pyridinonato oxidovanadium(IV) complexes to investigate structure/activity relationships.

    PubMed

    Rangel, Maria; Amorim, M João; Nunes, Ana; Leite, Andreia; Pereira, Eulália; de Castro, Baltazar; Sousa, Carla; Yoshikawa, Yutaka; Sakurai, Hiromu

    2009-04-01

    A previous evaluation of the insulin-like activity of three 3-hydroxy-4-pyridinonato oxidovanadium(IV) complexes raised questions about structure/activity relationships, namely the influence of the hydrophilic/lipophilic balance of the complex and the capacity of the ligand to stabilize the +4 oxidation state of vanadium ion, on achieving an positive effect. To address these questions, we synthesized six new oxidovanadium(IV) complexes with variable hydrophilic/lipophilic balance, obtained by introducing different substituents on the nitrogen atom, and used two 3-hydroxy-4-pyrones as starting reagents to provide methyl and ethyl groups in the ortho position of the ring. For the new and previously reported complexes, we studied the oxidation-reduction properties and insulin-like activity in terms of inhibitory effect on Free fatty acid (FFA) release in isolated rat adipocytes. The results obtained show that only one of the complexes, Bis(3-hydroxy-1(H)-2-methyl-4-pyridonato)oxidovanadium(IV), VO(mpp)(2), exhibits a significantly greater capacity to inhibit FFA release than VOSO(4) and consequently is worthy to be considered for further studies. The establishment of structure activity relationships was not attainable but this study brings new information about the influence of some properties of the compounds on the achievement of an insulin-like effect. The results reveal that: (i) the oxidation-reduction cycles of the complexes are identical; (ii) the presence of more lipophilic substituents on the nitrogen atom does not enhance insulin-like properties; (iii) a high solubility in water proved to be not sufficient for a positive activity in inhibiting FFA release; (iv) a small molecular size may be an important property for reaching the right targets. PMID:19195710

  12. Quantitative structure-activity relationship correlation between molecular structure and the Rayleigh enantiomeric enrichment factor.

    PubMed

    Jammer, S; Rizkov, D; Gelman, F; Lev, O

    2015-08-01

    It was recently demonstrated that under environmentally relevant conditions the Rayleigh equation is valid to describe the enantiomeric enrichment - conversion relationship, yielding a proportional constant called the enantiomeric enrichment factor, εER. In the present study we demonstrate a quantitative structure-activity relationship model (QSAR) that describes well the dependence of εER on molecular structure. The enantiomeric enrichment factor can be predicted by the linear Hansch model, which correlates biological activity with physicochemical properties. Enantioselective hydrolysis of sixteen derivatives of 2-(phenoxy)propionate (PPMs) have been analyzed during enzymatic degradation by lipases from Pseudomonas fluorescens (PFL), Pseudomonas cepacia (PCL), and Candida rugosa (CRL). In all cases the QSAR relationships were significant with R(2) values of 0.90-0.93, and showed high predictive abilities with internal and external validations providing QLOO(2) values of 0.85-0.87 and QExt(2) values of 0.8-0.91. Moreover, it is demonstrated that this model enables differentiation between enzymes with different binding site shapes. The enantioselectivity of PFL and PCL was dictated by electronic properties, whereas the enantioselectivity of CRL was determined by lipophilicity and steric factors. The predictive ability of the QSAR model demonstrated in the present study may serve as a helpful tool in environmental studies, assisting in source tracking of unstudied chiral compounds belonging to a well-studied homologous series. PMID:26153539

  13. Conceptualizing the Suicide-Alcohol Relationship.

    ERIC Educational Resources Information Center

    Rogers, James R.

    Despite the strong empirical evidence linking alcohol use across varying levels to suicidal behavior, the field is lacking a unifying theoretical framework in this area. The concept of alcohol induced myopia to explain the varied effects of alcohol on the behaviors of individuals who drink has been proposed. The term "alcohol myopia" refers to its…

  14. Percutaneous absorption of herbicides derived from 2,4-dichlorophenoxyacid: structure-activity relationship.

    PubMed

    Beydon, Dominique; Payan, Jean-Paul; Ferrari, Elisabeth; Grandclaude, Marie-Christine

    2014-08-01

    Ethyl to octyl esters of 2,4-dichlorophenoxy-acetic acids (2,4DAA), 2,4-dichlorophenoxy-propionic acids (2,4DPA) or 2,4-dichlorophenoxy-butyric acids (2,4DBA) are present in the most commonly used herbicides. Their use involves a significant risk of skin exposure, but little is known about the percutaneous flux of these substances. Studies have shown that percutaneous transition of esters may be dependent on their hydrolysis by esterases present in the skin. In this study, we describe ex vivo percutaneous absorption of seven pure esters (methyl to decyl) with a 2,4DA structure for rats (n=6) and humans (n=7). Esters were applied at 50 μL cm(-2) to dermatomed skin (approximately 0.5 mm thick) for 24 h. The enzymatic constants for hydrolysis of each ester by skin esterases were determined in vitro using skin homogenates from both species. Structure-activity relationships linking the evolution of the ex vivo percutaneous flux of esters and the 2,4D structure with enzymatic (Vmax; Km) and/or physical parameters (molecular weight, molecular volume, size of the ester, log(kow)) were examined to develop a good flux estimation model. Although the percutaneous penetration of all of the esters of the 2,4D family are "esterase-dependent", the decreasing linear relationship between percutaneous penetration and hyrophobicity defined by the logarithm for the octanol-water partition coefficient (log(kow)) is the most pertinent model for estimating the percutaneous absorption of esters for both species. The mean flux of the free acid production by the esterases of the skin is not the limiting factor for percutaneous penetration. The rate of hydrolysis of the esters in the skin decreases linearly with log(kow), which would suggest that either the solubility of the esters in the zones of the skin that are rich in esterases or the accessibility to the active sites of the enzyme is the key factor. The structure-activity relationship resulting from this study makes it possible, in

  15. Structure-Activity Relationship for Fe(III)-Salen-Like Complexes as Potent Anticancer Agents

    PubMed Central

    Ghanbari, Zahra; Housaindokht, Mohammad R.; Izadyar, Mohammad; Bozorgmehr, Mohammad R.; Eshtiagh-Hosseini, Hossein; Bahrami, Ahmad R.; Matin, Maryam M.; Khoshkholgh, Maliheh Javan

    2014-01-01

    Quantitative structure activity relationship (QSAR) for the anticancer activity of Fe(III)-salen and salen-like complexes was studied. The methods of density function theory (B3LYP/LANL2DZ) were used to optimize the structures. A pool of descriptors was calculated: 1497 theoretical descriptors and quantum-chemical parameters, shielding NMR, and electronic descriptors. The study of structure and activity relationship was performed with multiple linear regression (MLR) and artificial neural network (ANN). In nonlinear method, the adaptive neuro-fuzzy inference system (ANFIS) was applied in order to choose the most effective descriptors. The ANN-ANFIS model with high statistical significance (R2train = 0.99, RMSE = 0.138, and Q2LOO = 0.82) has better capability to predict the anticancer activity of the new compounds series of this family. Based on this study, anticancer activity of this compound is mainly dependent on the geometrical parameters, position, and the nature of the substituent of salen ligand. PMID:24955417

  16. A quantitative structure-activity relationship model for radical scavenging activity of flavonoids.

    PubMed

    Om, A; Kim, J H

    2008-03-01

    A quantitative structure-activity relationship (QSAR) study has been carried out for a training set of 29 flavonoids to correlate and predict the 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity (RSA) values obtained from published data. Genetic algorithm and multiple linear regression were employed to select the descriptors and to generate the best prediction model that relates the structural features to the RSA activities using (1) three-dimensional (3D) Dragon (TALETE srl, Milan, Italy) descriptors and (2) semi-empirical descriptor calculations. The predictivity of the models was estimated by cross-validation with the leave-one-out method. The result showed that a significant improvement of the statistical indices was obtained by deleting outliers. Based on the data for the compounds used in this study, our results suggest a QSAR model of RSA that is based on the following descriptors: 3D-Morse, WHIM, and GETAWAY. Therefore, satisfactory relationships between RSA and the semi-empirical descriptors were found, demonstrating that the energy of the highest occupied molecular orbital, total energy, and energy of heat of formation contributed more significantly than all other descriptors. PMID:18361735

  17. Method for the evaluation of structure-activity relationship information associated with coordinated activity cliffs.

    PubMed

    Dimova, Dilyana; Stumpfe, Dagmar; Bajorath, Jürgen

    2014-08-14

    Activity cliffs are generally defined as pairs of active compounds having a large difference in potency. Although this definition of activity cliffs focuses on compound pairs, the vast majority of cliffs are formed in a coordinated manner. This means that multiple highly and weakly potent compounds form series of activity cliffs, which often overlap. In activity cliff networks, coordinated cliffs emerge as disjoint activity cliff clusters. Recently, we have identified all cliff clusters from current bioactive compounds and analyzed their topologies. For structure-activity relationship (SAR) analysis, activity cliff clusters are of high interest, since they contain more SAR information than cliffs that are individually considered. For medicinal chemistry applications, a key question becomes how to best extract SAR information from activity cliff clusters. This represents a challenging problem, given the complexity of many activity cliff configurations. Herein we introduce a generally applicable methodology to organize activity cliff clusters on the basis of structural relationships, prioritize clusters, and systematically extract SAR information from them. PMID:25014781

  18. Structure-activity relationship for Fe(III)-salen-like complexes as potent anticancer agents.

    PubMed

    Ghanbari, Zahra; Housaindokht, Mohammad R; Izadyar, Mohammad; Bozorgmehr, Mohammad R; Eshtiagh-Hosseini, Hossein; Bahrami, Ahmad R; Matin, Maryam M; Khoshkholgh, Maliheh Javan

    2014-01-01

    Quantitative structure activity relationship (QSAR) for the anticancer activity of Fe(III)-salen and salen-like complexes was studied. The methods of density function theory (B3LYP/LANL2DZ) were used to optimize the structures. A pool of descriptors was calculated: 1497 theoretical descriptors and quantum-chemical parameters, shielding NMR, and electronic descriptors. The study of structure and activity relationship was performed with multiple linear regression (MLR) and artificial neural network (ANN). In nonlinear method, the adaptive neuro-fuzzy inference system (ANFIS) was applied in order to choose the most effective descriptors. The ANN-ANFIS model with high statistical significance (R (2) train = 0.99, RMSE = 0.138, and Q (2) LOO = 0.82) has better capability to predict the anticancer activity of the new compounds series of this family. Based on this study, anticancer activity of this compound is mainly dependent on the geometrical parameters, position, and the nature of the substituent of salen ligand. PMID:24955417

  19. Development and Validation of Quantitative Structure-Activity Relationship Models for Compounds Acting on Serotoninergic Receptors

    PubMed Central

    Żydek, Grażyna; Brzezińska, Elżbieta

    2012-01-01

    A quantitative structure-activity relationship (QSAR) study has been made on 20 compounds with serotonin (5-HT) receptor affinity. Thin-layer chromatographic (TLC) data and physicochemical parameters were applied in this study. RP2 TLC 60F254 plates (silanized) impregnated with solutions of propionic acid, ethylbenzene, 4-ethylphenol, and propionamide (used as analogues of the key receptor amino acids) and their mixtures (denoted as S1–S7 biochromatographic models) were used in two developing phases as a model of drug-5-HT receptor interaction. The semiempirical method AM1 (HyperChem v. 7.0 program) and ACD/Labs v. 8.0 program were employed to calculate a set of physicochemical parameters for the investigated compounds. Correlation and multiple linear regression analysis were used to search for the best QSAR equations. The correlations obtained for the compounds studied represent their interactions with the proposed biochromatographic models. The good multivariate relationships (R2 = 0.78–0.84) obtained by means of regression analysis can be used for predicting the quantitative effect of biological activity of different compounds with 5-HT receptor affinity. “Leave-one-out” (LOO) and “leave-N-out” (LNO) cross-validation methods were used to judge the predictive power of final regression equations. PMID:22619602

  20. Applying quantitative structure-activity relationship approaches to nanotoxicology: current status and future potential.

    PubMed

    Winkler, David A; Mombelli, Enrico; Pietroiusti, Antonio; Tran, Lang; Worth, Andrew; Fadeel, Bengt; McCall, Maxine J

    2013-11-01

    The potential (eco)toxicological hazard posed by engineered nanoparticles is a major scientific and societal concern since several industrial sectors (e.g. electronics, biomedicine, and cosmetics) are exploiting the innovative properties of nanostructures resulting in their large-scale production. Many consumer products contain nanomaterials and, given their complex life-cycle, it is essential to anticipate their (eco)toxicological properties in a fast and inexpensive way in order to mitigate adverse effects on human health and the environment. In this context, the application of the structure-toxicity paradigm to nanomaterials represents a promising approach. Indeed, according to this paradigm, it is possible to predict toxicological effects induced by chemicals on the basis of their structural similarity with chemicals for which toxicological endpoints have been previously measured. These structure-toxicity relationships can be quantitative or qualitative in nature and they can predict toxicological effects directly from the physicochemical properties of the entities (e.g. nanoparticles) of interest. Therefore, this approach can aid in prioritizing resources in toxicological investigations while reducing the ethical and monetary costs that are related to animal testing. The purpose of this review is to provide a summary of recent key advances in the field of QSAR modelling of nanomaterial toxicity, to identify the major gaps in research required to accelerate the use of quantitative structure-activity relationship (QSAR) methods, and to provide a roadmap for future research needed to achieve QSAR models useful for regulatory purposes. PMID:23165187

  1. Prediction of compounds in different local structure-activity relationship environments using emerging chemical patterns.

    PubMed

    Namasivayam, Vigneshwaran; Gupta-Ostermann, Disha; Balfer, Jenny; Heikamp, Kathrin; Bajorath, Jürgen

    2014-05-27

    Active compounds can participate in different local structure-activity relationship (SAR) environments and introduce different degrees of local SAR discontinuity, depending on their structural and potency relationships in data sets. Such SAR features have thus far mostly been analyzed using descriptive approaches, in particular, on the basis of activity landscape modeling. However, compounds in different local SAR environments have not yet been predicted. Herein, we adapt the emerging chemical patterns (ECP) method, a machine learning approach for compound classification, to systematically predict compounds with different local SAR characteristics. ECP analysis is shown to accurately assign many compounds to different local SAR environments across a variety of activity classes covering the entire range of observed local SARs. Control calculations using random forests and multiclass support vector machines were carried out and a variety of statistical performance measures were applied. In all instances, ECP calculations yielded comparable or better performance than controls. The approach presented herein can be applied to predict compounds that complement local SARs or prioritize compounds with different SAR characteristics. PMID:24803014

  2. Young People and Alcohol in Italy: An Evolving Relationship

    ERIC Educational Resources Information Center

    Beccaria, Franca; Prina, Franco

    2010-01-01

    In Italy, commonly held opinions and interpretations about the relationship between young people and alcohol are often expressed as generalizations and approximations. In order to further understanding of the relationship between young people and alcohol in contemporary Italy, we have gathered, compared and discussed all the available data, both…

  3. Introducing Spectral Structure Activity Relationship (S-SAR) Analysis. Application to Ecotoxicology

    PubMed Central

    Putz, Mihai V.; Lacrămă, Ana-Maria

    2007-01-01

    A novel quantitative structure-activity (property) relationship model, namely Spectral-SAR, is presented in an exclusive algebraic way replacing the old-fashioned multi-regression one. The actual S-SAR method interprets structural descriptors as vectors in a generic data space that is further mapped into a full orthogonal space by means of the Gram-Schmidt algorithm. Then, by coordinated transformation between the data and orthogonal spaces, the S-SAR equation is given under simple determinant form for any chemical-biological interactions under study. While proving to give the same analytical equation and correlation results with standard multivariate statistics, the actual S-SAR frame allows the introduction of the spectral norm as a valid substitute for the correlation factor, while also having the advantage to design the various related SAR models through the introduced “minimal spectral path” rule. An application is given performing a complete S-SAR analysis upon the Tetrahymena pyriformis ciliate species employing its reported eco-toxicity activities among relevant classes of xenobiotics. By representing the spectral norm of the endpoint models against the concerned structural coordinates, the obtained S-SAR endpoints hierarchy scheme opens the perspective to further design the ecotoxicological test batteries with organisms from different species.

  4. Structure-activity relationships of novel substituted naphthalene diimides as anticancer agents.

    PubMed

    Milelli, Andrea; Tumiatti, Vincenzo; Micco, Marialuisa; Rosini, Michela; Zuccari, Guendalina; Raffaghello, Lizzia; Bianchi, Giovanna; Pistoia, Vito; Fernando Díaz, J; Pera, Benet; Trigili, Chiara; Barasoain, Isabel; Musetti, Caterina; Toniolo, Marianna; Sissi, Claudia; Alcaro, Stefano; Moraca, Federica; Zini, Maddalena; Stefanelli, Claudio; Minarini, Anna

    2012-11-01

    Novel 1,4,5,8-naphthalenetetracarboxylic diimide (NDI) derivatives were synthesized and evaluated for their antiproliferative activity on a wide number of different tumor cell lines. The prototypes of the present series were derivatives 1 and 2 characterized by interesting biological profiles as anticancer agents. The present investigation expands on the study of structure-activity relationships of prototypes 1 and 2, namely, the influence of the different substituents of the phenyl rings on the biological activity. Derivatives 3-22, characterized by a different substituent on the aromatic rings and/or a different chain length varying from two to three carbon units, were synthesized and evaluated for their cytostatic and cytotoxic activities. The most interesting compound was 20, characterized by a linker of three methylene units and a 2,3,4-trimethoxy substituent on the two aromatic rings. It displayed antiproliferative activity in the submicromolar range, especially against some different cell lines, the ability to inhibit Taq polymerase and telomerase, to trigger caspase activation by a possible oxidative mechanism, to downregulate ERK 2 protein and to inhibit ERKs phosphorylation, without acting directly on microtubules and tubuline. Its theoretical recognition against duplex and quadruplex DNA structures have been compared to experimental thermodynamic measurements and by molecular modeling investigation leading to putative binding modes. Taken together these findings contribute to define this compound as potential Multitarget-Directed Ligands interacting simultaneously with different biological targets. PMID:22819507

  5. Pyrazole derivatives as photosynthetic electron transport inhibitors: new leads and structure-activity relationship.

    PubMed

    Vicentini, Chiara B; Guccione, Salvatore; Giurato, Laura; Ciaccio, Rebecca; Mares, Donatella; Forlani, Giuseppe

    2005-05-18

    Four series of new pyrazoles, namely, 5 4-carboxypyrazolo-3-tert-butylcarboxamide and 6 4-carboxypyrazolo-3-cyclopropylcarboxamide derivatives and 10 pyrazolo[3,4-d][1,3]thiazine-4-one and 9 pyrazolo[3,4-d][1,3]thiazine-4-thione derivatives, were synthesized and screened as potential inhibitors of photosynthetic electron transport. The structures were confirmed by 1H NMR, elemental, and IR analyses. Their biological activity was evaluated in vitro as the ability to interfere with the light-driven reduction of ferricyanide by isolated spinach chloroplasts. Only a few compounds exhibited excellent inhibitory properties in the micromolar range, comparable to those of commercial herbicides sharing the same target, such as diuron, lenacil, and hexazinone. Nevertheless, most of the remaining molecules exerted a remarkable inhibition in the millimolar range. Combined with previous results on 6 pyrazolo[1,5-a][1,3,5]triazine-2,4-dione and 4 pyrazolo[1,5-c][1,3,5]thiadiazine-2-one derivatives, these data allowed a comprehensive analysis of structure-activity relationship. Molecular modeling studies were undertaken to rationalize the structural determinants of activity in terms of shape, size, and molecular fields. Results suggested that the inhibitory potential of these compounds is associated mainly with their electrostatic properties. PMID:15884806

  6. Synthesis, biological evaluation and structure-activity relationship of 2-styrylquinazolones as anti-tubercular agents.

    PubMed

    Jadhavar, Pradeep S; Dhameliya, Tejas M; Vaja, Maulikkumar D; Kumar, Dinesh; Sridevi, Jonnalagadda Padma; Yogeeswari, Perumal; Sriram, Dharmarajan; Chakraborti, Asit K

    2016-06-01

    2-Styrylquinazolones are reported as a novel class of potent anti-mycobacterial agents. Forty-six target compounds have been synthesized using one pot reaction involving isatoic anhydride, amine, and triethyl orthoacetate followed by aldehyde to construct the 2-styrylquinazolone scaffold. The anti-mycobacterial potency of the compounds was determined against H37Rv strain. Twenty-six compounds exhibited anti-Mtb activity in the range of 0.40-6.25μg/mL. Three compounds 8c, 8d and 8ab showed MIC of 0.78μg/mL and were found to be non-toxic (<50% inhibition at 50μg/mL) to HEK 293T cell lines with the therapeutic index >64. The most potent compound 8ar showed MIC of 0.40μg/mL with the therapeutic index >125. An early structure activity relationship for this class of compounds has been established. The computational studies indicate the possibility of these compounds binding to the penicillin binding proteins (PBPs). PMID:27095514

  7. The expert system for toxicity prediction of chemicals based on structure-activity relationship.

    PubMed Central

    Nakadate, M; Hayashi, M; Sofuni, T; Kamata, E; Aida, Y; Osada, T; Ishibe, T; Sakamura, Y; Ishidate, M

    1991-01-01

    The prediction systems of chemical toxicity has been developed by means of structure-activity relationship based on the computerized fact database (BL-DB). Numbers and ratio of elements, side chains, bonding, position, and microenvironment of side chains were used as structural factors of the chemical for the prediction. Such information was obtained from the BL-DB database by Wiswesser line-formula chemical notation. In the present study, the Salmonella/microsome assay was chosen as indicative of the target toxicity of chemicals. A set of chemicals specified with mutagenicity data was retrieved, and necessary information was extracted and transferred to the working file. Rules of the relations between characteristics of chemical structure and the assay result are extracted as parameters for rules by experts on the rearranged data set. These were analyzed statistically by the discriminant analysis and the prediction with the rules were evaluated by the elimination method. Eight kinds of rules to predict Salmonella/microsome assay were constructed, and currently results of the assay on aliphatic and heterocyclic compounds can be predicted as accurately as +90%. PMID:1820282

  8. Antimicrobial profile of some novel keto esters: Synthesis, crystal structures and structure-activity relationship studies.

    PubMed

    Khan, Imtiaz; Saeed, Aamer; Arshad, Mohammad Ifzan; White, Jonathan Michael

    2016-01-01

    Rapid increase in bacterial resistance has become a major public concern by escalating alongside a lack of development of new anti-infective drugs. Novel remedies in the battle against multidrug-resistant bacterial strains are urgently needed. So, in this context, the present work is towards the investigation of antimicrobial efficacy of some novel keto ester derivatives, which are prepared by the condensation of substituted benzoic acids with various substituted phenacyl bromides in dimethylformamide at room temperature using triethylamine as a catalyst. The structural build-up of the target compounds was accomplished by spectroscopic techniques including FTIR, (1)H and (13)C NMR spectroscopy and mass spectrometry. The purity of the synthesized compounds was ascertained by elemental analysis. The molecular structures of compounds (4b) and (4l) were established by X-ray crystallographic analysis. The prepared analogues were evaluated for their antimicrobial activity against Gram-positive (Staphylococcus aureus, Micrococcus leuteus) and Gram-negative (Pseudomonas picketti, Salmonella setuball) bacteria and two fungal pathogenic strains (Aspergillus niger, Aspergillus flavus), respectively. Among the screened derivatives, several compounds were found to possess significant activity but (4b) and (4l) turned out to be lead molecules with remarkable antimicrobial efficacy. The structure-activity relationship analysis of this study also revealed that structural modifications on the basic skeleton affected the antimicrobial activity of the synthesized compounds. PMID:26826838

  9. Structure-Activity Relationship Study of Novel Peptoids That Mimic the Structure of Antimicrobial Peptides

    PubMed Central

    Mojsoska, Biljana; Zuckermann, Ronald N.

    2015-01-01

    The constant emergence of new bacterial strains that resist the effectiveness of marketed antimicrobials has led to an urgent demand for and intensive research on new classes of compounds to combat bacterial infections. Antimicrobial peptoids comprise one group of potential candidates for antimicrobial drug development. The present study highlights a library of 22 cationic amphipathic peptoids designed to target bacteria. All the peptoids share an overall net charge of +4 and are 8 to 9 residues long; however, the hydrophobicity and charge distribution along the abiotic backbone varied, thus allowing an examination of the structure-activity relationship within the library. In addition, the toxicity profiles of all peptoids were assessed in human red blood cells (hRBCs) and HeLa cells, revealing the low toxicity exerted by the majority of the peptoids. The structural optimization also identified two peptoid candidates, 3 and 4, with high selectivity ratios of 4 to 32 and 8 to 64, respectively, and a concentration-dependent bactericidal mode of action against Gram-negative Escherichia coli. PMID:25941221

  10. Structure-Activity Relationships of the Peptide Kappa Opioid Receptor Antagonist Zyklophin.

    PubMed

    Joshi, Anand A; Murray, Thomas F; Aldrich, Jane V

    2015-11-25

    The dynorphin (Dyn) A analogue zyklophin ([N-benzyl-Tyr(1)-cyclo(d-Asp(5),Dap(8))]dynorphin A(1-11)NH2) is a kappa opioid receptor (KOR)-selective antagonist in vitro, is active in vivo, and antagonizes KOR in the CNS after systemic administration. Hence, we synthesized zyklophin analogues to explore the structure-activity relationships of this peptide. The synthesis of selected analogues required modification to introduce the N-terminal amino acid due to poor solubility and/or to avoid epimerization of this residue. Among the N-terminal modifications, the N-phenethyl and N-cyclopropylmethyl substitutions resulted in analogues with the highest KOR affinities. Pharmacological results for the alanine-substituted analogues indicated that Phe(4) and Arg(6), but interestingly not the Tyr(1) phenol, are important for zyklophin's KOR affinity and that Arg(7) was important for KOR antagonist activity. In the GTPγS assay, while all of the cyclic analogues exhibited negligible KOR efficacy, the N-cyclopropylmethyl-Tyr(1) and N-benzyl-Phe(1) analogues were 28- and 11-fold more potent KOR antagonists, respectively, than zyklophin. PMID:26491810

  11. Selective COX-2 Inhibitors: A Review of Their Structure-Activity Relationships

    PubMed Central

    Zarghi, Afshin; Arfaei, Sara

    2011-01-01

    Non-steroidal anti-inflammatory drugs (NSAIDs) are the competitive inhibitors of cyclooxygenase (COX), the enzyme which mediates the bioconversion of arachidonic acid to inflammatory prostaglandins (PGs). Their use is associated with the side effects such as gastrointestinal and renal toxicity. The therapeutic anti-inflammatory action of NSAIDs is produced by the inhibition of COX-2, while the undesired side effects arise from inhibition of COX-1 activity. Thus, it was though that more selective COX-2 inhibitors would have reduced side effects. Based upon a number of selective COX-2 inhibitors (rofecoxib, celecoxib, valdecoxibetc.) were developed as safer NSAIDs with improved gastric safety profile. However, the recent market removal of some COXIBs such as rofecoxib due to its adverse cardiovascular side effects clearly encourages the researchers to explore and evaluate alternative templates with COX-2 inhibitory activity. Recognition of new avenues for selective COX-2 inhibitors in cancer chemotherapy and neurological diseases such as Parkinson and Alzheimer’s diseases still continues to attract investigations on the development of COX-2 inhibitors. This review highlights the various structural classes of selective COX-2 inhibitors with special emphasis on their structure-activity relationships. PMID:24250402

  12. Structure-activity relationships for substrate-based inhibitors of human complement factor B.

    PubMed

    Ruiz-Gómez, Gloria; Lim, Junxian; Halili, Maria A; Le, Giang T; Madala, Praveen K; Abbenante, Giovanni; Fairlie, David P

    2009-10-01

    Human complement is a cascading network of plasma proteins important in immune defense, cooperatively effecting recognition, opsonization, destruction, and removal of pathogens and infected/damaged cells. Overstimulated or unregulated complement activation can result in immunoinflammatory diseases. Key serine proteases in this cascade are difficult to study due to their multiprotein composition, short lifetimes, formation on membranes, or serum circulation as inactive zymogens. Factor B is inactive at pH 7, but a catalytically active serine protease under alkaline conditions, enabling structure-activity relationship studies for 63 substrate-based peptide inhibitors with 4-7 residues and a C-terminal aldehyde. A potent factor B inhibitor was hexpeptide Ac-RLTbaLAR-H (IC(50) 250 nM, pH 9.5), which at pH 7 also blocked formation of membrane attack complex via the "alternative pathway" of complement activation and inhibited human complement mediated lysis of rabbit erythrocytes. Inhibitors of factor B may be valuable probes and drug leads for complement mediated immunity and disease. PMID:19743866

  13. Structure-activity relationship studies on clinically relevant HIV-1 NNRTIs.

    PubMed

    Rawal, R K; Murugesan, V; Katti, S B

    2012-01-01

    In addition to the nucleoside reverse transcriptase inhibitors (NRTIs), protease inhibitors (PIs) and integrase inhibitors (INIs), nonnucleoside reverse transcriptase inhibitors (NNRTIs) have contributed significantly in the treatment of HIV-1 infections. More than 60 structurally different classes of compounds have been identified as NNRTIs, which are specifically inhibiting HIV-1 reverse transcriptase (RT). Five NNRTIs (nevirapine, delavirdine, efavirenz, etravirine and rilpivirine) have been approved by US Food and Drug Administration (FDA) for clinical use. The NNRTIs bind with a specific 'pocket' site of HIV-1 RT (allosteric site) that is closely associated with the NRTI binding site. Due to mutations of the amino acid residues surrounding the NNRTI-binding site, NNRTIs are notorious for rapidly eliciting resistance. Though, the emergence of resistant HIV strains can be circumvented if the NNRTIs are used either alone or in combination with NRTIs (AZT, 3TC, ddI, ddC, TVD or d4T) and PIs (Indinavir, nelfinavir, saquinavir, ritonavir and lopinavir etc.) as shown by both a decrease in plasma HIV-1 RNA levels and increased CD4 T-cells. Here we are going to discuss recent advances in structure activity relationship studies on nevirapine, delavirdine, efavirenz, etravirine, rilpivirine and 4-thiazolidinones (privileged scaffold) HIV-1 NNRTIs. PMID:22998569

  14. A structure-activity relationship for induction of meningeal inflammation by muramyl peptides.

    PubMed Central

    Burroughs, M; Rozdzinski, E; Geelen, S; Tuomanen, E

    1993-01-01

    Components of bacterial peptidoglycans have potent biological activities, including adjuvant effects, cytotoxicity, and induction of sleep. Mixtures of peptidoglycan components also induce inflammation in the lung, subarachnoid space, and joint, but the structural requirements for activity are unknown. Using a rabbit model for meningitis, we determined the biological activities of 14 individual muramyl peptides constituting > 90% of the peptidoglycan of the gram-negative pediatric pathogen Haemophilus influenzae. Upon intracisternal inoculation, most of the muropeptides induced leukocytosis in cerebrospinal fluid (CSF), influx of protein into CSF, or brain edema, alone or in combination. The disaccharide-tetrapeptide, the major component of all gram-negative peptidoglycans, induced CSF leukocytosis and protein influx at doses as low as 0.4 microgram (0.42 nM). Modification of the N-acetyl muramic acid or substitution of the alanine at position four in the peptide side chain decreased leukocytosis but enhanced brain edema. As the size of the muropeptide increased, the inflammatory activity decreased. Muropeptide carrying the diaminopimelyl-diaminopimelic acid cross-link specifically induced cytotoxic brain edema. These findings significantly expand the spectrum of biological activities of natural muramyl peptides and provide the basis for a structure-activity relationship for the inflammatory properties of bacterial muropeptides. PMID:8325996

  15. Synthesis and Structure-Activity Relationships of Substituted Urea Derivatives on Mouse Melanocortin Receptors.

    PubMed

    Singh, Anamika; Kast, Johannes; Dirain, Marvin L S; Huang, Huisuo; Haskell-Luevano, Carrie

    2016-02-17

    The melanocortin system is involved in the regulation of several complex physiological functions. In particular, the melanocortin-3 and -4 receptors (MC3R/MC4R) have been demonstrated to regulate body weight, energy homeostasis, and feeding behavior. Synthetic and endogenous melanocortin agonists have been shown to be anorexigenic in rodent models. Herein, we report synthesis and structure-activity relationship (SAR) studies of 27 nonpeptide small molecule ligands based on an unsymmetrical substituted urea core. Three templates containing key residues from the lead compounds, showing diversity at three positions (R(1), R(2), R(3)), were designed and synthesized. The syntheses were optimized for efficient microwave-assisted chemistry that significantly reduced total syntheses time compared to a previously reported room temperature method. The pharmacological characterization of the compounds on the mouse melanocortin receptors identified compounds 1 and 12 with full agonist activity at the mMC4R, but no activity was observed at the mMC3R when tested up to 100 μM concentrations. The SAR identified compounds possessing aliphatic or saturated cyclic amines at the R(1) position, bulky aromatic groups at the R(2) position, and benzyl group at the R(3) position resulted in mMC4R selectivity over the mMC3R. The small molecule template and SAR knowledge from this series may be helpful in further design of MC3R/MC4R selective small molecule ligands. PMID:26645732

  16. Natural and Synthetic Flavonoids: Structure-Activity Relationship and Chemotherapeutic Potential for the Treatment of Leukemia.

    PubMed

    Menezes, José C J M D S; Orlikova, Barbora; Morceau, Franck; Diederich, Marc

    2016-07-29

    Flavonoids and their derivatives are polyphenolic secondary metabolites with an extensive spectrum of pharmacological activities, including antioxidants, antitumor, anti-inflammatory, and antiviral activities. These flavonoids can also act as chemopreventive agents by their interaction with different proteins and can play a vital role in chemotherapy, suggesting a positive correlation between a lower risk of cancer and a flavonoid-rich diet. These agents interfere with the main hallmarks of cancer by various individual mechanisms, such as inhibition of cell growth and proliferation by arresting the cell cycle, induction of apoptosis and differentiation, or a combination of these mechanisms. This review is an effort to highlight the therapeutic potential of natural and synthetic flavonoids as anticancer agents in leukemia treatment with respect to the structure-activity relationship (SAR) and their molecular mechanisms. Induction of cell death mechanisms, production of reactive oxygen species, and drug resistance mechanisms, including p-glycoprotein efflux, are among the best-described effects triggered by the flavonoid polyphenol family. PMID:26463658

  17. Gold(I) thiolates containing amino acid moieties. Cytotoxicity and structure-activity relationship studies.

    PubMed

    Gutiérrez, Alejandro; Gracia-Fleta, Lucia; Marzo, Isabel; Cativiela, Carlos; Laguna, Antonio; Gimeno, M Concepción

    2014-12-01

    Several gold(I) complexes containing a thiolate ligand functionalised with several amino acid or peptide moieties of the type [Au(SPyCOR)(PPh2R')] (where R = OH, amino acid or dipeptide and R' = Ph or Py) were prepared. These thiolate gold complexes bearing biological molecules possess potential use as antitumor agents. Cytotoxicity assays in different tumour cell lines such as A549 (lung carcinoma), Jurkat (T-cell leukaemia) and MiaPaca2 (pancreatic carcinoma) revealed that the complexes exhibit good antiproliferative activity, with IC50 values in the low micromolar range. Several structural modifications such as in the type of phosphine, number of metal atoms and amino acid (type, stereochemistry and functionalisation) were carried out in order to establish the structure-activity relationship in this family of complexes, which has led to the design of new and more potent cytotoxic complexes. Observations of different cellular events after addition of the complexes indicated the possible mechanism of action or the biological targets of this type of new gold(I) drug. PMID:25302929

  18. Structure-Activity Relationships in Human Toll-like Receptor 7-Active Imidazoquinoline Analogues

    PubMed Central

    Shukla, Nikunj M.; Malladi, Subbalakshmi S.; Mutz, Cole A.; Balakrishna, Rajalakshmi; David, Sunil A.

    2010-01-01

    Engagement of toll-like receptors serve to link innate immune responses with adaptive immunity and can be exploited as powerful vaccine adjuvants for eliciting both primary and anamnestic immune responses. TLR7 agonists are highly immunostimulatory without inducing dominant proinflammatory cytokine responses. A structure-activity study was conducted on the TLR7-agonistic imidazoquinolines, starting with 1-(4-amino-2-((ethylamino)methyl)-1H-imidazo[4,5-c]quinolin-1-yl)-2-methylpropan-2-ol as a lead. Modifications of the secondary amine of the C2 ethylaminomethylene sidechain are poorly tolerated. The 4-amino group must be retained for activity. Replacement of the imidazole ring of the scaffold with triazole or cyclic urea led to complete loss of activity. A systematic exploration of N1-benzyl-C2-alkyl substituents showed a very distinct relationship between alkyl length and TLR7-agonistic potency with the optimal compound bearing a C2-n-butyl group. Transposition of the N1 and C2 substituents led to the identification of an extremely active TLR7-agonistic compound with an EC50 value of 8.6 nM. The relative potencies in human TLR7-based primary reporter gene assays were paralleled by interferon-α induction activities in whole human blood models. PMID:20481492

  19. Quantitative structure-activity relationships and the prediction of MHC supermotifs.

    PubMed

    Doytchinova, Irini A; Guan, Pingping; Flower, Darren R

    2004-12-01

    The underlying assumption in quantitative structure-activity relationship (QSAR) methodology is that related chemical structures exhibit related biological activities. We review here two QSAR methods in terms of their applicability for human MHC supermotif definition. Supermotifs are motifs that characterise binding to more than one allele. Supermotif definition is the initial in silico step of epitope-based vaccine design. The first QSAR method we review here--the additive method--is based on the assumption that the binding affinity of a peptide depends on contributions from both amino acids and the interactions between them. The second method is a 3D-QSAR method: comparative molecular similarity indices analysis (CoMSIA). Both methods were applied to 771 peptides binding to 9 HLA alleles. Five of the alleles (A*0201, A*0202, A*0203, A*0206 and A*6802) belong to the HLA-A2 superfamily and the other four (A*0301, A*1101, A*3101 and A*6801) to the HLA-A3 superfamily. For each superfamily, supermotifs defined by the two QSAR methods agree closely and are supported by many experimental data. PMID:15542370

  20. Structure-activity relationship study at C9 position of kaitocephalin.

    PubMed

    Yasuno, Yoko; Hamada, Makoto; Yoshida, Yuya; Shimamoto, Keiko; Shigeri, Yasushi; Akizawa, Toshifumi; Konishi, Motomi; Ohfune, Yasufumi; Shinada, Tetsuro

    2016-08-01

    Kaitocephalin (KCP) isolated from Eupenicillium shearii PF1191 is an unusual amino acid natural product in which serine, proline, and alanine moieties are liked with carbon-carbon bonds. KCP exhibits potent and selective binding affinity for one of the ionotropic glutamate receptor subtypes, NMDA receptors (Ki=7.8nM). In this study, new structure-activity relationship studies at C9 of KCP were implemented. Eleven new KCP analogs with different substituents at C9 were prepared and employed for binding affinity tests using native ionotropic glutamate receptors. Replacement of the 3,5-dichloro-4-hydroxybenzoyl group of KCP with a 3-phenylpropionyl group resulted in significant loss of binding affinity for NMDARs (Ki=1300nM), indicating an indispensable role of the aromatic ring of KCP in the potent and selective binding to NMDARs. Other analogs showed potent binding affinity in a range of 11-270nM. These findings would directly link to develop useful chemical tools toward imaging and labeling of NMDARs. PMID:27329796

  1. Predicting Cell Association of Surface-Modified Nanoparticles Using Protein Corona Structure - Activity Relationships (PCSAR).

    PubMed

    Kamath, Padmaja; Fernandez, Alberto; Giralt, Francesc; Rallo, Robert

    2015-01-01

    Nanoparticles are likely to interact in real-case application scenarios with mixtures of proteins and biomolecules that will absorb onto their surface forming the so-called protein corona. Information related to the composition of the protein corona and net cell association was collected from literature for a library of surface-modified gold and silver nanoparticles. For each protein in the corona, sequence information was extracted and used to calculate physicochemical properties and statistical descriptors. Data cleaning and preprocessing techniques including statistical analysis and feature selection methods were applied to remove highly correlated, redundant and non-significant features. A weighting technique was applied to construct specific signatures that represent the corona composition for each nanoparticle. Using this basic set of protein descriptors, a new Protein Corona Structure-Activity Relationship (PCSAR) that relates net cell association with the physicochemical descriptors of the proteins that form the corona was developed and validated. The features that resulted from the feature selection were in line with already published literature, and the computational model constructed on these features had a good accuracy (R(2)LOO=0.76 and R(2)LMO(25%)=0.72) and stability, with the advantage that the fingerprints based on physicochemical descriptors were independent of the specific proteins that form the corona. PMID:25961528

  2. Quantitative structure-activity relationship models for prediction of the toxicity of polybrominated diphenyl ether congeners.

    PubMed

    Wang, Yawei; Liu, Huanxiang; Zhao, Chunyan; Liu, Hanxia; Cai, Zongwei; Jiang, Guibin

    2005-07-01

    Levels of polybrominated diphenyl ethers (PBDEs) are increasing in the environment and may cause long-term health problems in humans. The similarity in the chemical structures of PBDEs and other halogenated aromatic pollutants hints on the possibility that they might share similar toxicological effects. In this work, three-dimensional quantitative structure activity relationships (3-D-QSAR) models, using comparative molecular field analysis (CoMFA) and comparative similarity indices analysis (CoMSIA), were built based on calculated structural indices and a reported experimental toxicology index (aryl hydrocarbon receptor relative binding affinities, RBA) of 18 PBDEs congeners, to determine the factors required for the RBA of these PBDEs. After performing leave-one-out cross-validation, satisfactory results were obtained with cross-validation O2 and R2 values of 0.580 and 0.995 by the CoMFA model and 0.680 and 0.982 by the CoMSIA model, respectively. The results showed clearly that the nonplanar conformations of PBDEs result in the lowest energy level and that the electrostatic index was the main factor reflecting the RBA of PBDEs. The two QSAR models were then used to predict the RBA value of 46 PBDEs for which experimental values are unavailable at present. PMID:16053097

  3. A Categorical Structure-Activity Relationship Analysis of the Developmental Toxicity of Antithyroid Drugs

    PubMed Central

    Cunningham, Albert R.; Carrasquer, C. Alex; Mattison, Donald R.

    2009-01-01

    The choice of therapeutic strategies for hyperthyroidism during pregnancy is limited. Surgery and radioiodine are typically avoided, leaving propylthiouracil and methimazole in the US. Carbimazole, a metabolic precursor of methimazole, is available in some countries outside of the US. In the US propylthiouracil is recommended because of concern about developmental toxicity from methimazole and carbimazole. Despite this recommendation, the data on developmental toxicity of all three agents are extremely limited and insufficient to support a policy given the broad use of methimazole and carbimazole around the world. In the absence of new human or animal data we describe the development of a new structure-activity relationship (SAR) model for developmental toxicity using the cat-SAR expert system. The SAR model was developed from data for 323 compounds evaluated for human developmental toxicity with 130 categorized as developmental toxicants and 193 as nontoxicants. Model cross-validation yielded a concordance between observed and predicted results between 79% to 81%. Based on this model, propylthiouracil, methimazole, and carbimazole were observed to share some structural features relating to human developmental toxicity. Thus given the need to treat women with Graves's disease during pregnancy, new molecules with minimized risk for developmental toxicity are needed. To help meet this challenge, the cat-SAR method would be a useful in screening new drug candidates for developmental toxicity as well as for investigating their mechanism of action. PMID:20111734

  4. Red Wine Tannin Structure-Activity Relationships during Fermentation and Maceration.

    PubMed

    Yacco, Ralph S; Watrelot, Aude A; Kennedy, James A

    2016-02-01

    The correlation between tannin structure and corresponding activity was investigated by measuring the thermodynamics of interaction between tannins isolated from commercial red wine fermentations and a polystyrene divinylbenzene HPLC column. Must and/or wine samples were collected throughout fermentation/maceration from five Napa Valley wineries. By varying winery, fruit source, maceration time, and cap management practice, it was considered that a reasonably large variation in commercially relevant tannin structure would result. Tannins were isolated from samples collected using low pressure chromatography and were then characterized by gel permeation chromatography and acid-catalyzed cleavage in the presence of excess phloroglucinol (phloroglucinolysis). Corresponding tannin activity was determined using HPLC by measuring the thermodynamics of interaction between isolated tannin and a polystyrene divinylbenzene HPLC column. This measurement approach was designed to determine the ability of tannins to hydrophobically interact with a hydrophobic surface. The results of this study indicate that tannin activity is primarily driven by molecular size. Compositionally, tannin activity was positively associated with seed tannins and negatively associated with skin and pigmented tannins. Although measured indirectly, the extent of tannin oxidation as determined by phloroglucinolysis conversion yield suggests that tannin oxidation at this stage of production reduces tannin activity. Based upon maceration time, this study indicates that observed increases in perceived astringency quality, if related to tannin chemistry, are driven by tannin molecular mass as opposed to pigmented tannin formation or oxidation. Overall, the results of this study give new insight into tannin structure-activity relationships which dominate during extraction. PMID:26766301

  5. A quantitative structure--activity relationship model for the intrinsic activity of uncouplers of oxidative phosphorylation.

    PubMed

    Spycher, Simon; Escher, Beate I; Gasteiger, Johann

    2005-12-01

    A quantitative structure-activity relationship (QSAR) has been derived for the prediction of the activity of phenols in uncoupling oxidative and photophosphorylation. Twenty-one compounds with experimental data for uncoupling activity as well as for the acid dissociation constant, pKa, and for partitioning constants of the neutral and the charged species into model membranes were analyzed. From these measured data, the effective concentration in the membrane was derived, which allowed the study of the intrinsic activity of uncouplers within the membrane. A linear regression model for the intrinsic activity could be established using the following three descriptors: solvation free energies of the anions, an estimate for heterodimer formation describing transport processes, and pKa values describing the speciation of the phenols. In a next step, the aqueous effect concentrations were modeled by combining the model for the intrinsic uncoupling activity with descriptors accounting for the uptake into membranes. Results obtained with experimental membrane-water partitioning data were compared with the results obtained with experimental octanol-water partition coefficients, log Kow, and with calculated log Kow values. The properties of these different measures of lipophilicity were critically discussed. PMID:16359176

  6. Quantitative structure-activity relationships for weak acid respiratory uncouplers to Vibrio fisheri

    SciTech Connect

    Schultz, T.W.; Cronin, M.T.D.

    1997-02-01

    Acute toxicity values of 16 organic compounds thought to elicit their response via the weak acid respiratory uncoupling mechanism of toxic action were secured from the literature. Regression analysis of toxicities revealed that a measured 5-min V. fisheri potency value can be used as a surrogate for the 30-min value. Regression analysis of toxicity versus hydrophobicity, measured as the 1-octanol/water partition coefficient (log K{sub ow}), was used to formulate a quantitative structure-activity relationship (QSAR). The equation log pT{sub 30}{sup {minus}1} = 0.489(log K{sub ow}) + 0.126 was found to be a highly predictive model. This V. fisheri QSAR is statistically similar to QSARs generated from weak acid uncoupler potency data for Pimephales promelas survivability and Tetrahymena pyriformis population growth impairment. This work, therefore, suggests that the weak acid respiratory uncoupling mechanism of toxic action is present in V. fisheri, and as such is not restricted to mitochondria-containing organisms.

  7. Structure-Activity Relationships in Toll-like Receptor-2 agonistic Diacylthioglycerol Lipopeptides

    PubMed Central

    Wu, Wenyan; Li, Rongti; Malladi, Subbalakshmi S.; Warshakoon, Hemamali J.; Kimbrell, Matthew R.; Amolins, Michael W.; Ukani, Rehman; Datta, Apurba; David, Sunil A.

    2010-01-01

    The N-termini of bacterial lipoproteins are acylated with a (S)-(2,3-bisacyloxypropyl)cysteinyl residue. Lipopeptides derived from lipoproteins activate innate immune responses by engaging Toll-like receptor 2 (TLR2), and are highly immunostimulatory and yet without apparent toxicity in animal models. The lipopeptides may therefore be useful as potential immunotherapeutic agents. Previous structure-activity relationships in such lipopeptides have largely been obtained using murine cells and it is now clear that significant species-specific differences exist between human and murine TLR responses. We have examined in detail the role of the highly conserved Cys residue as well as the geometry and stereochemistry of the Cys-Ser dipeptide unit. (R)-diacylthioglycerol analogues are maximally active in reporter gene assays using human TLR2. The Cys-Ser dipeptide unit represents the minimal part-structure, but its stereochemistry was found not to be a critical determinant of activity. The thioether bridge between the diacyl and dipeptide units is crucial, and replacement by an oxoether bridge results in a dramatic decrease in activity. PMID:20302301

  8. Acute toxicity estimation by calculation--Tubifex assay and quantitative structure-activity relationships.

    PubMed

    Tichý, Milon; Rucki, Marian; Hanzlíková, Iveta; Roth, Zdenek

    2008-11-01

    A quantitative structure-activity relationship (QSAR) model dependent on log P(n - octanol/water), or log P(OW), was developed with acute toxicity index EC50, the median effective concentration measured as inhibition of movement of the oligochaeta Tubifex tubifex with 3 min exposure, EC50(Tt) (mol/L): log EC50(Tt) = -0.809 (+/-0.035) log P(OW) - 0.495 (+/-0.060), n=82, r=0.931, r2=0.867, residual standard deviation of the estimate 0.315. A learning series for the QSAR model with the oligochaete contained alkanols, alkenols, and alkynols; saturated and unsaturated aldehydes; aniline and chlorinated anilines; phenol and chlorinated phenols; and esters. Three cross-validation procedures proved the robustness and stability of QSAR models with respect to the chemical structure of compounds tested within a series of compounds used in the learning series. Predictive ability was described by q2 .801 (cross-validated r2; predicted variation estimated with cross-validation) in LSO (leave-a structurally series-out) cross-validation. PMID:18522479

  9. Structure-Activity Relationships for the Antifungal Activity of Selective Estrogen Receptor Antagonists Related to Tamoxifen

    PubMed Central

    Butts, Arielle; Martin, Jennifer A.; DiDone, Louis; Bradley, Erin K.; Mutz, Mitchell; Krysan, Damian J.

    2015-01-01

    Cryptococcosis is one of the most important invasive fungal infections and is a significant contributor to the mortality associated with HIV/AIDS. As part of our program to repurpose molecules related to the selective estrogen receptor modulator (SERM) tamoxifen as anti-cryptococcal agents, we have explored the structure-activity relationships of a set of structurally diverse SERMs and tamoxifen derivatives. Our data provide the first insights into the structural requirements for the antifungal activity of this scaffold. Three key molecular characteristics affecting anti-cryptococcal activity emerged from our studies: 1) the presence of an alkylamino group tethered to one of the aromatic rings of the triphenylethylene core; 2) an appropriately sized aliphatic substituent at the 2 position of the ethylene moiety; and 3) electronegative substituents on the aromatic rings modestly improved activity. Using a cell-based assay of calmodulin antagonism, we found that the anti-cryptococcal activity of the scaffold correlates with calmodulin inhibition. Finally, we developed a homology model of C. neoformans calmodulin and used it to rationalize the structural basis for the activity of these molecules. Taken together, these data and models provide a basis for the further optimization of this promising anti-cryptococcal scaffold. PMID:26016941

  10. Phytotoxicity of umbelliferone and its analogs: Structure-activity relationships and action mechanisms.

    PubMed

    Pan, Le; Li, Xiu-Zhuang; Yan, Zhi-Qiang; Guo, Hong-Ru; Qin, Bo

    2015-12-01

    Two coumarins, umbelliferone and daphnoretin, were isolated from roots of Stellera chamaejasme L; the former had been identified as one of the main allelochemicals in our previous studies. Both of them have the skeleton of 7-hydroxycoumarin, but showed different phytotoxic effects. Umbelliferone and its analogs were then prepared to investigate the structure-activity relationship of hydroxycoumarins and screened for phytotoxicity. The inhibitory effects varied observably in response to the coumarin derivatives, especially umbelliferone (1), 7-hydroxy-4-methylcoumarin (3) and coumarin (10) displayed strong inhibition of lettuce and two field weeds, Setaria viridis and Amaranthus retroflexus, and compounds 11 and 12 also exhibited phytotoxic activity with species specificity. The number and location of hydroxyl groups were importantly responsible for the phytotoxicity. A C7 hydroxyl group was considered to be a potentially active site and methyl substitution at the C4 position contributed significantly to the activity. The phytotoxic mechanism was briefly studied with umbelliferone by evaluating the reactive oxygen species (ROS) and chlorophylls level in lettuce seedlings. The results showed that umbelliferone induced the accumulation of ROS in the root tip and significantly decreased the chlorophyll content in the leaves. Thus, a ROS-mediated regulation pathway and the inhibition of photosynthesis were definitely involved in the phytotoxicity of umbelliferone. PMID:26509496

  11. Targeted Mutations of Bacillus anthracis Dihydrofolate Reductase Condense Complex Structure-Activity Relationships

    SciTech Connect

    J Beierlein; N Karri; A Anderson

    2011-12-31

    Several antifolates, including trimethoprim (TMP) and a series of propargyl-linked analogues, bind dihydrofolate reductase from Bacillus anthracis (BaDHFR) with lower affinity than is typical in other bacterial species. To guide lead optimization for BaDHFR, we explored a new approach to determine structure-activity relationships whereby the enzyme is altered and the analogues remain constant, essentially reversing the standard experimental design. Active site mutants of the enzyme, Ba(F96I)DHFR and Ba(Y102F)DHFR, were created and evaluated with enzyme inhibition assays and crystal structures. The affinities of the antifolates increase up to 60-fold with the Y102F mutant, suggesting that interactions with Tyr 102 are critical for affinity. Crystal structures of the enzymes bound to TMP and propargyl-linked inhibitors reveal the basis of TMP resistance and illuminate the influence of Tyr 102 on the lipophilic linker between the pyrimidine and aryl rings. Two new inhibitors test and validate these conclusions and show the value of the technique for providing new directions during lead optimization.

  12. Derivatives of Ergot-alkaloids: Molecular structure, physical properties, and structure-activity relationships

    NASA Astrophysics Data System (ADS)

    Ivanova, Bojidarka B.; Spiteller, Michael

    2012-09-01

    A comprehensive screening of fifteen functionalized Ergot-alkaloids, containing bulk aliphatic cyclic substituents at D-ring of the ergoline molecular skeleton was performed, studying their structure-active relationships and model interactions with α2A-adreno-, serotonin (5HT2A) and dopamine D3 (D3A) receptors. The accounted high affinity to the receptors binding loops and unusual bonding situations, joined with the molecular flexibility of the substituents and the presence of proton accepting/donating functional groups in the studied alkaloids, may contribute to further understanding the mechanisms of biological activity in vivo and in predicting their therapeutic potential in central nervous system (CNS), including those related the Schizophrenia. Since the presented correlation between the molecular structure and properties, was based on the comprehensively theoretical computational and experimental physical study on the successfully isolated derivatives, through using routine synthetic pathways in a relatively high yields, marked these derivatives as 'treasure' for further experimental and theoretical studied in areas such as: (a) pharmacological and clinical testing; (b) molecular-drugs design of novel psychoactive substances; (c) development of the analytical protocols for determination of Ergot-alkaloids through a functionalization of the ergoline-skeleton, and more.

  13. Quantitative structure-activity relationships for the mutagenicity of propylene oxides with Salmonella.

    PubMed

    Hooberman, B H; Chakraborty, P K; Sinsheimer, J E

    1993-04-01

    A quantitative structure-activity relationship approach was used to investigate the mutagenicity of a series of seventeen-monosubstituted propylene oxides in Salmonella typhimurium strains TA100 and TA1535. Mutagenicity in strain TA100, using a liquid suspension assay, was found to correlate with chemical reactivity, as measured by the rates of reaction with two model bionucleophiles, nicotinamide and 4-(4-nitrobenzyl)pyridine. However, since the reactivity of three of the epoxides did not correlate to their Taft sigma * values, as a measure of the electronic effects of substituent groups, neither was their mutagenicity predicted by this substituent constant. The relative mutagenicity for the propylene oxides was different in the liquid suspension assay than that determined by the standard plate incorporation assay and also differed between the two bacterial strains. The assay differences were attributed to epoxide stability. The differences between strains was observed to be due to the response of the error-prone repair system, found only in TA100, to the stronger alkylating agents. PMID:7680427

  14. Utilization of quantitative structure-activity relationships (QSARs) in risk assessment: Alkylphenols

    SciTech Connect

    Beck, B.D.; Toole, A.P.; Callahan, B.G.; Siddhanti, S.K. )

    1991-12-01

    Alkylphenols are a class of environmentally pervasive compounds, found both in natural (e.g., crude oils) and in anthropogenic (e.g., wood tar, coal gasification waste) materials. Despite the frequent environmental occurrence of these chemicals, there is a limited toxicity database on alkylphenols. The authors have therefore developed a 'toxicity equivalence approach' for alkylphenols which is based on their ability to inhibit, in a specific manner, the enzyme cyclooxygenase. Enzyme-inhibiting ability for individual alkylphenols can be estimated based on the quantitative structure-activity relationship developed by Dewhirst (1980) and is a function of the free hydroxyl group, electron-donating ring substituents, and hydrophobic aromatic ring substituents. The authors evaluated the toxicological significance of cyclooxygenase inhibition by comparison of the inhibitory capacity of alkylphenols with the inhibitory capacity of acetylsalicylic acid, or aspirin, a compound whose low-level effects are due to cyclooxygenase inhibition. Since nearly complete absorption for alkylphenols and aspirin is predicted, based on estimates of hydrophobicity and fraction of charged molecules at gastrointestinal pHs, risks from alkylphenols can be expressed directly in terms of 'milligram aspirin equivalence,' without correction for absorption differences. They recommend this method for assessing risks of mixtures of alkylphenols, especially for those compounds with no chronic toxicity data.38 references.

  15. The Structure-Activity Relationship between Marine Algae Polysaccharides and Anti-Complement Activity.

    PubMed

    Jin, Weihua; Zhang, Wenjing; Liang, Hongze; Zhang, Quanbin

    2016-01-01

    In this study, 33 different polysaccharides were prepared to investigate the structure-activity relationships between the polysaccharides, mainly from marine algae, and anti-complement activity in the classical pathway. Factors considered included extraction methods, fractionations, molecular weight, molar ratio of galactose to fucose, sulfate, uronic acid (UA) content, linkage, branching, and the type of monosaccharide. It was shown that the larger the molecular weights, the better the activities. The molar ratio of galactose (Gal) to fucose (Fuc) was a positive factor at a concentration lower than 10 µg/mL, while it had no effect at a concentration more than 10 µg/mL. In addition, sulfate was necessary; however, the sulfate content, the sulfate pattern, linkage and branching had no effect at a concentration of more than 10 µg/mL. Moreover, the type of monosaccharide had no effect. Laminaran and UA fractions had no activity; however, they could reduce the activity by decreasing the effective concentration of the active composition when they were mixed with the active compositions. The effect of the extraction methods could not be determined. Finally, it was observed that sulfated galactofucan showed good anti-complement activity after separation. PMID:26712768

  16. Extracellular melanogenesis inhibitory activity and the structure-activity relationships of ugonins from Helminthostachys zeylanica roots.

    PubMed

    Yamauchi, Kosei; Mitsunaga, Tohru; Itakura, Yuki; Batubara, Irmanida

    2015-07-01

    Ugonin J, K, and L, which are luteolin derivatives, were isolated from Helminthostachys zeylanica roots by a series of chromatographic separations of a 50% ethanol/water extract. They were identified using nuclear magnetic resonance (NMR), ultraviolet (UV) spectra, and ultra-performance liquid chromatography coupled to time-of-flight mass spectrometry (UPLC-TOF-MS). In this study, the intra and extracellular melanogenic activity of the ugonins were determined using B16 melanoma cells. The results showed that ugonin J at 12.5, 25, and 50μM reduced extracellular melanin contents to 75, 16, and 14%, respectively, compared to the control. This indicates that ugonin J showed a stronger activity than arbutin, used as the positive control. Moreover, ugonin K showed a more potent inhibition with 19, 8, and 9% extracellular melanin reduction at the same concentrations, than that shown by ugonin J. In contrast, ugonin L did not inhibit intra- or extracellular melanogenic activity. Furthermore, in order to investigate the structure-activity relationships of the ugonins, the intra- and extracellular melanogenic activity of luteolin, methylluteolin, quercetin, eriodictyol, apigenin, and chrysin were determined. Consequently, it was suggested that the catechol and flavone skeleton of ugonin K is essential for the extracellular melanogenic inhibitory activity, and the low polarity substituent groups on the A ring of ugonin K may increase the activity. PMID:25979512

  17. Structure-Activity Relationships of the Bioactive Thiazinoquinone Marine Natural Products Thiaplidiaquinones A and B

    PubMed Central

    Harper, Jacquie L.; Khalil, Iman M.; Shaw, Lisa; Bourguet-Kondracki, Marie-Lise; Dubois, Joëlle; Valentin, Alexis; Barker, David; Copp, Brent R.

    2015-01-01

    In an effort to more accurately define the mechanism of cell death and to establish structure-activity relationship requirements for the marine meroterpenoid alkaloids thiaplidiaquinones A and B, we have evaluated not only the natural products but also dioxothiazine regioisomers and two precursor quinones in a range of bioassays. While the natural products were found to be weak inducers of ROS in Jurkat cells, the dioxothiazine regioisomer of thiaplidiaquinone A and a synthetic precursor to thiaplidiaquinone B were found to be moderately potent inducers. Intriguingly, and in contrast to previous reports, the mechanism of Jurkat cell death (necrosis vs. apoptosis) was found to be dependent upon the positioning of one of the geranyl sidechains in the compounds with thiaplidiaquinone A and its dioxothiazine regioisomer causing death dominantly by necrosis, while thiaplidiaquinone B and its dioxothiazine isomer caused cell death via apoptosis. The dioxothiazine regioisomer of thiaplidiaquinone A exhibited more potent in vitro antiproliferative activity against human tumor cells, with NCI sub-panel selectivity towards melanoma cell lines. The non-natural dioxothiazine regioisomers were also more active in antiplasmodial and anti-farnesyltransferase assays than their natural product counterparts. The results highlight the important role that natural product total synthesis can play in not only helping understand the structural basis of biological activity of natural products, but also the discovery of new bioactive scaffolds. PMID:26266415

  18. Quantitative structure-activity relationships for the toxicity of nitrobenzenes to Tetrahymena thermophila.

    PubMed

    Xu, Jing-Bo; Jing, Ti-Song; Pauli, W; Berger, S

    2002-01-01

    In this study IGC50 (50% inhibitory growth concentration) values of 26 nitrobenzenes were determined for population growth endpoint of Tetrahymena thermophila. The toxicity order of the observed compounds has been found as follows: dinitro compounds > mono-nitro compounds; dichloronitrobenzenes > monochloronitrobenzenes; and meta-substituted nitrobenzenes > ortho-/para-substituted nitrobenzenes (NT, NPh, NAnis) except for the dinitrobenzenes and nitroanilines (DNB, NAn). Quantitative structure activity relationships (QSARs) were developed using log of the inverse of the IGC50 (logIGC50(-1)) in mole liter as the dependent variable and six molecular descriptors--logP, 1X(V), I, K alpha, sigma sigma- and E(LUMO) as the independent variables. Through multiplicate regression analysis, one best equation was obtained: log IGC50(-1) = 2.93 + 0.830sigma sigma- + 0.350I, n = 26, r = 0.923, r2 = 0.852, s = 0.265, f = 66.4 The equation was used to estimate IGC50 for seven analogues. PMID:12046656

  19. Structure-Activity Relationships of the Bioactive Thiazinoquinone Marine Natural Products Thiaplidiaquinones A and B.

    PubMed

    Harper, Jacquie L; Khalil, Iman M; Shaw, Lisa; Bourguet-Kondracki, Marie-Lise; Dubois, Joëlle; Valentin, Alexis; Barker, David; Copp, Brent R

    2015-08-01

    In an effort to more accurately define the mechanism of cell death and to establish structure-activity relationship requirements for the marine meroterpenoid alkaloids thiaplidiaquinones A and B, we have evaluated not only the natural products but also dioxothiazine regioisomers and two precursor quinones in a range of bioassays. While the natural products were found to be weak inducers of ROS in Jurkat cells, the dioxothiazine regioisomer of thiaplidiaquinone A and a synthetic precursor to thiaplidiaquinone B were found to be moderately potent inducers. Intriguingly, and in contrast to previous reports, the mechanism of Jurkat cell death (necrosis vs. apoptosis) was found to be dependent upon the positioning of one of the geranyl sidechains in the compounds with thiaplidiaquinone A and its dioxothiazine regioisomer causing death dominantly by necrosis, while thiaplidiaquinone B and its dioxothiazine isomer caused cell death via apoptosis. The dioxothiazine regioisomer of thiaplidiaquinone A exhibited more potent in vitro antiproliferative activity against human tumor cells, with NCI sub-panel selectivity towards melanoma cell lines. The non-natural dioxothiazine regioisomers were also more active in antiplasmodial and anti-farnesyltransferase assays than their natural product counterparts. The results highlight the important role that natural product total synthesis can play in not only helping understand the structural basis of biological activity of natural products, but also the discovery of new bioactive scaffolds. PMID:26266415

  20. Synthesis and antioxidant evaluation of isochroman-derivatives of hydroxytyrosol: structure-activity relationship.

    PubMed

    Mateos, Raquel; Madrona, Andrés; Pereira-Caro, Gema; Domínguez, Vanessa; Cert, Rosa M A; Parrado, Juan; Sarriá, Beatriz; Bravo, Laura; Espartero, José Luis

    2015-04-15

    Isochroman-derivatives of the natural olive oil phenol hydroxytyrosol (HT) have been synthesised via Oxa-Pictet-Spengler reaction in high yields. Lipophilicity and antioxidant activity were determined to establish the structure-activity relationship of isochromans compared to HT, BHT and α-tocopherol. Antioxidant capacity was tested in two different media: bulk oils, using the Rancimat test, and brain homogenates, by measuring malondialdehyde (MDA) levels as a lipoperoxidation biomarker. In addition, other antioxidant assays (FRAP, ABTS and ORAC) were carried out. Rancimat and MDA results show that antioxidant activity was related with lipophilicity, directly in brain homogenates and inversely in the oils, in agreement with the polar paradox. Free o-diphenolic groups positively determined the activity in the oils, whereas reducing and radical-scavenging activities were related to the number of free hydroxyl moieties. BHT and α-tocopherol showed lower antioxidant activity than isochromans and HT. We conclude that HT-isochromans present significant potential as bioactive compounds. PMID:25466028

  1. Quorum Sensing Inhibition and Structure-Activity Relationships of β-Keto Esters.

    PubMed

    Forschner-Dancause, Stephanie; Poulin, Emily; Meschwitz, Susan

    2016-01-01

    Traditional therapeutics to treat bacterial infections have given rise to multi-drug resistant pathogens, which pose a major threat to human and animal health. In several pathogens, quorum sensing (QS)-a cell-cell communication system in bacteria-controls the expression of genes responsible for pathogenesis, thus representing a novel target in the fight against bacterial infections. Based on the structure of the autoinducers responsible for QS activity and other QS inhibitors, we hypothesize that β-keto esters with aryl functionality could possess anti-QS activity. A panel of nineteen β-keto ester analogs was tested for the inhibition of bioluminescence (a QS-controlled phenotype) in the marine pathogen Vibrio harveyi. Initial screening demonstrated the need of a phenyl ring at the C-3 position for antagonistic activity. Further additions to the phenyl ring with 4-substituted halo groups or a 3- or 4-substituted methoxy group resulted in the most active compounds with IC50 values ranging from 23 µM to 53 µM. The compounds additionally inhibit green fluorescent protein production by E. coli JB525. Evidence is presented that aryl β-keto esters may act as antagonists of bacterial quorum sensing by competing with N-acyl homoserine lactones for receptor binding. Expansion of the β-keto ester panel will enable us to obtain more insight into the structure-activity relationships needed to allow for the development of novel anti-virulence agents. PMID:27463706

  2. Deep neural nets as a method for quantitative structure-activity relationships.

    PubMed

    Ma, Junshui; Sheridan, Robert P; Liaw, Andy; Dahl, George E; Svetnik, Vladimir

    2015-02-23

    Neural networks were widely used for quantitative structure-activity relationships (QSAR) in the 1990s. Because of various practical issues (e.g., slow on large problems, difficult to train, prone to overfitting, etc.), they were superseded by more robust methods like support vector machine (SVM) and random forest (RF), which arose in the early 2000s. The last 10 years has witnessed a revival of neural networks in the machine learning community thanks to new methods for preventing overfitting, more efficient training algorithms, and advancements in computer hardware. In particular, deep neural nets (DNNs), i.e. neural nets with more than one hidden layer, have found great successes in many applications, such as computer vision and natural language processing. Here we show that DNNs can routinely make better prospective predictions than RF on a set of large diverse QSAR data sets that are taken from Merck's drug discovery effort. The number of adjustable parameters needed for DNNs is fairly large, but our results show that it is not necessary to optimize them for individual data sets, and a single set of recommended parameters can achieve better performance than RF for most of the data sets we studied. The usefulness of the parameters is demonstrated on additional data sets not used in the calibration. Although training DNNs is still computationally intensive, using graphical processing units (GPUs) can make this issue manageable. PMID:25635324

  3. Representation of molecular structure using quantum topology with inductive logic programming in structure-activity relationships.

    PubMed

    Buttingsrud, Bård; Ryeng, Einar; King, Ross D; Alsberg, Bjørn K

    2006-06-01

    The requirement of aligning each individual molecule in a data set severely limits the type of molecules which can be analysed with traditional structure activity relationship (SAR) methods. A method which solves this problem by using relations between objects is inductive logic programming (ILP). Another advantage of this methodology is its ability to include background knowledge as 1st-order logic. However, previous molecular ILP representations have not been effective in describing the electronic structure of molecules. We present a more unified and comprehensive representation based on Richard Bader's quantum topological atoms in molecules (AIM) theory where critical points in the electron density are connected through a network. AIM theory provides a wealth of chemical information about individual atoms and their bond connections enabling a more flexible and chemically relevant representation. To obtain even more relevant rules with higher coverage, we apply manual postprocessing and interpretation of ILP rules. We have tested the usefulness of the new representation in SAR modelling on classifying compounds of low/high mutagenicity and on a set of factor Xa inhibitors of high and low affinity. PMID:17054018

  4. Structure-Activity Relationships in Toll-like Receptor 2-Agonists Leading to Simplified Monoacyl Lipopeptides

    PubMed Central

    Agnihotri, Geetanjali; Crall, Breanna M.; Lewis, Tyler C.; Day, Timothy P.; Balakrishna, Rajalakshmi; Warshakoon, Hemamali J.; Malladi, Subbalakshmi S.; David, Sunil A.

    2011-01-01

    Toll-like receptor 2-agonistic lipopeptides typified by S-[2,3-bis(palmitoyloxy)-(2RS)-propyl]-R-cysteinyl-S-serine (PAM2CS) compounds are potential vaccine adjuvants. In continuation of previously reported structure-activity relationships on this chemotype, we have determined that at least one acyl group of optimal length (C16) and an appropriately orientated ester carbonyl group is essential for TLR2-agonistic activity. The spacing between one of the palmitoyl ester carbonyl and the thioether is crucial to allow for an important H-bond, which observed in the crystal structure of the lipopeptide:TLR2 complex; consequently, activity is lost in homologated compounds. Penicillamine-derived analogues are also inactive, likely due to unfavorable steric interactions with the carbonyl of Ser 12 in TLR2. The thioether in this chemotype can be replaced with a selenoether. Importantly, the thioglycerol motif can be dispensed with altogether, and can be replaced with a thioethanol bridge. These results have led to a structurally simpler, synthetically more accessible, and water-soluble analogue possessing strong TLR2-agonistic activities in human blood. PMID:22007676

  5. The Structure Activity Relationship of Urea Derivatives as Anti-Tuberculosis Agents

    PubMed Central

    Brown, Joshua R.; North, Elton J.; Hurdle, Julian G.; Morisseau, Christophe; Scarborough, Jerrod S.; Sun, Dianqing; Korduláková, Jana; Scherman, Michael S.; Jones, Victoria; Grzegorzewicz, Anna; Crew, Rebecca M.; Jackson, Mary; McNeil, Michael R.; Lee, Richard E.

    2011-01-01

    The treatment of tuberculosis is becoming more difficult due to the ever increasing prevalence of drug resistance. Thus, it is imperative that novel anti-tuberculosis agents, with unique mechanisms of action, be discovered and developed. The direct anti-tubercular testing of a small compound library led to discovery of adamantyl urea hit compound 1. In this study, the hit was followed up through the synthesis of an optimization library. This library was generated by systematically replacing each section of the molecule with a similar moiety until a clear structure activity relationship was obtained with respect to anti-tubercular activity. The best compounds in this series contained a 1-adamantyl-3-phenyl urea core and had potent activity against Mycobacterium tuberculosis plus an acceptable therapeutic index. It was noted that the compounds identified and the pharmacophore developed is consistent with inhibitors of epoxide hydrolase family of enzymes. Consequently, the compounds were tested for inhibition of representative epoxide hydrolases: M. tuberculosis EphB and EphE; and human soluble epoxide hydrolase. Many of the optimized inhibitors showed both potent EphB and EphE inhibition suggesting the antitubercular activity is through inhibition of multiple epoxide hydrolyase enzymes. The inhibitors also showed potent inhibition of humans soluble expoxide hydrolyase, but limited cytotoxicity suggesting that future studies must be towards increasing the selectivity of epoxide hydrolyase inhibition towards the M. tuberculosis enzymes. PMID:21840723

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

    PubMed

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

    2016-05-17

    New energetic compounds are designed to minimize their potential environmental impacts, which includes their transformation and the fate and effects of their transformation products. The nitro groups of energetic compounds are readily reduced to amines, and the resulting aromatic amines are subject to oxidation and coupling reactions. Manganese dioxide (MnO2) is a common environmental oxidant and model system for kinetic studies of aromatic amine oxidation. In this study, a training set of new and previously reported kinetic data for the oxidation of model and energetic-derived aromatic amines was assembled and subjected to correlation analysis against descriptor variables that ranged from general purpose [Hammett σ constants (σ(-)), pKas of the amines, and energies of the highest occupied molecular orbital (EHOMO)] to specific for the likely rate-limiting step [one-electron oxidation potentials (Eox)]. The selection of calculated descriptors (pKa, EHOMO, and Eox) was based on validation with experimental data. All of the correlations gave satisfactory quantitative structure-activity relationships (QSARs), but they improved with the specificity of the descriptor. The scope of correlation analysis was extended beyond MnO2 to include literature data on aromatic amine oxidation by other environmentally relevant oxidants (ozone, chlorine dioxide, and phosphate and carbonate radicals) by correlating relative rate constants (normalized to 4-chloroaniline) to EHOMO (calculated with a modest level of theory). PMID:27074054

  7. The Structure-Activity Relationship between Marine Algae Polysaccharides and Anti-Complement Activity

    PubMed Central

    Jin, Weihua; Zhang, Wenjing; Liang, Hongze; Zhang, Quanbin

    2015-01-01

    In this study, 33 different polysaccharides were prepared to investigate the structure-activity relationships between the polysaccharides, mainly from marine algae, and anti-complement activity in the classical pathway. Factors considered included extraction methods, fractionations, molecular weight, molar ratio of galactose to fucose, sulfate, uronic acid (UA) content, linkage, branching, and the type of monosaccharide. It was shown that the larger the molecular weights, the better the activities. The molar ratio of galactose (Gal) to fucose (Fuc) was a positive factor at a concentration lower than 10 µg/mL, while it had no effect at a concentration more than 10 µg/mL. In addition, sulfate was necessary; however, the sulfate content, the sulfate pattern, linkage and branching had no effect at a concentration of more than 10 µg/mL. Moreover, the type of monosaccharide had no effect. Laminaran and UA fractions had no activity; however, they could reduce the activity by decreasing the effective concentration of the active composition when they were mixed with the active compositions. The effect of the extraction methods could not be determined. Finally, it was observed that sulfated galactofucan showed good anti-complement activity after separation. PMID:26712768

  8. Trainable structure-activity relationship model for virtual screening of CYP3A4 inhibition.

    PubMed

    Didziapetris, Remigijus; Dapkunas, Justas; Sazonovas, Andrius; Japertas, Pranas

    2010-11-01

    A new structure-activity relationship model predicting the probability for a compound to inhibit human cytochrome P450 3A4 has been developed using data for >800 compounds from various literature sources and tested on PubChem screening data. Novel GALAS (Global, Adjusted Locally According to Similarity) modeling methodology has been used, which is a combination of baseline global QSAR model and local similarity based corrections. GALAS modeling method allows forecasting the reliability of prediction thus defining the model applicability domain. For compounds within this domain the statistical results of the final model approach the data consistency between experimental data from literature and PubChem datasets with the overall accuracy of 89%. However, the original model is applicable only for less than a half of PubChem database. Since the similarity correction procedure of GALAS modeling method allows straightforward model training, the possibility to expand the applicability domain has been investigated. Experimental data from PubChem dataset served as an example of in-house high-throughput screening data. The model successfully adapted itself to both data classified using the same and different IC₅₀ threshold compared with the training set. In addition, adjustment of the CYP3A4 inhibition model to compounds with a novel chemical scaffold has been demonstrated. The reported GALAS model is proposed as a useful tool for virtual screening of compounds for possible drug-drug interactions even prior to the actual synthesis. PMID:20814717

  9. Docking and quantitative structure-activity relationship of oxadiazole derivates as inhibitors of GSK3β.

    PubMed

    Quesada-Romero, Luisa; Caballero, Julio

    2014-02-01

    The binding modes of 42 oxadiazole derivates inside glycogen synthase kinase 3 beta (GSK3β were determined using docking experiments; thus, the preferred active conformations of these inhibitors are proposed. We found that these compounds adopt a scorpion-shaped conformation and they accept a hydrogen bond (HB) from the residue Val135 of the GSK3β ATP-binding site hinge region. In addition, quantitative structure-activity relationship (QSAR) models were constructed to explain the trend of the GSK3β inhibitory activities for the studied compounds. In a first approach, three-dimensional (3D) vectors were calculated using docking conformations and, by using multiple-linear regression, we assessed that GETAWAY vectors were able to describe the reported biological activities. In other QSAR approach, SMILES-based optimal descriptors were calculated. The best model included three-SMILES elements SSSβ leading to the identification of key molecular features that contribute to a high GSK3β inhibitory activity. PMID:24081608

  10. Synthesis, insecticidal activity, and structure-activity relationship (SAR) of anthranilic diamides analogs containing oxadiazole rings.

    PubMed

    Li, Yuhao; Zhu, Hongjun; Chen, Kai; Liu, Rui; Khallaf, Abdalla; Zhang, Xiangning; Ni, Jueping

    2013-06-28

    A series of anthranilic diamides analogs (3–11, 16–24) containing 1,2,4- or 1,3,4-oxadiazole rings were synthesized and characterized by (1)H NMR, MS and elemental analyses. The structure of 3-bromo-N-(2-(3-(4-bromophenyl)-1,2,4-oxadiazol-5-yl)-4-chloro-6-methylphenyl)-1-(3-chloropyridin-2-yl)-1H-pyrazole-5-carboxamide (18, CCDC-) was determined by X-ray diffraction crystallography. The insecticidal activities against Plutella xylostella and Spodoptera exigua were evaluated. The results showed that most of title compounds displayed good larvicidal activities against P. xylostella, especially compound 3-bromo-N-(4-chloro-2-methyl-6-(5-(methylthio)-1,3,4-oxadiazol-2-yl)phenyl)-1-(3-chloropyridin-2-yl)-1H-pyrazole-5-carboxamide (6), which displayed 71.43% activity against P. xylostella at 0.4 μg mL(-1) and 33.33% against S. exigua at 1 μg mL(-1). The structure-activity relationship showed that compounds decorated with a 1,3,4-oxadiazole were more potent than compounds decorated with a 1,2,4-oxadiazole, and different substituents attached to the oxadiazole ring also affected the insecticidal activity. This work provides some hints for further structure modification and the enhancement of insecticidal activity. PMID:23657615

  11. Automated Structure-Activity Relationship Mining: Connecting Chemical Structure to Biological Profiles.

    PubMed

    Wawer, Mathias J; Jaramillo, David E; Dančík, Vlado; Fass, Daniel M; Haggarty, Stephen J; Shamji, Alykhan F; Wagner, Bridget K; Schreiber, Stuart L; Clemons, Paul A

    2014-06-01

    Understanding the structure-activity relationships (SARs) of small molecules is important for developing probes and novel therapeutic agents in chemical biology and drug discovery. Increasingly, multiplexed small-molecule profiling assays allow simultaneous measurement of many biological response parameters for the same compound (e.g., expression levels for many genes or binding constants against many proteins). Although such methods promise to capture SARs with high granularity, few computational methods are available to support SAR analyses of high-dimensional compound activity profiles. Many of these methods are not generally applicable or reduce the activity space to scalar summary statistics before establishing SARs. In this article, we present a versatile computational method that automatically extracts interpretable SAR rules from high-dimensional profiling data. The rules connect chemical structural features of compounds to patterns in their biological activity profiles. We applied our method to data from novel cell-based gene-expression and imaging assays collected on more than 30,000 small molecules. Based on the rules identified for this data set, we prioritized groups of compounds for further study, including a novel set of putative histone deacetylase inhibitors. PMID:24710340

  12. Modular Synthesis of Heparan Sulfate Oligosaccharides for Structure-Activity Relationship Studies

    PubMed Central

    Arungundram, Sailaja; Al-Mafraji, Kanar; Asong, Jinkeng; Leach, Franklin E.; Amster, I. Jonathan; Venot, Andre; Turnbull, Jeremy E.; Boons, Geert-Jan

    2010-01-01

    Although hundreds of heparan sulfate binding proteins have been identified, and implicated in a myriad of physiological and pathological processes, very little information is known about ligand requirements for binding and mediating biological activities by these proteins. This difficulty results from a lack of technology for establishing structure-activity-relationships, which in turn is due to the structural complexity of natural heparan sulfate (HS) and difficulties of preparing well-defined HS-oligosaccharides. To address this deficiency, we have developed a modular approach for the parallel combinatorial synthesis of HS oligosaccharides that utilizes a relatively small number of selectively protected disaccharide building blocks, which can easily be converted into glycosyl donors and acceptors. The utility of the modular building blocks has been demonstrated by the preparation of a library of twelve oligosaccharides, which has been employed to probe structural features of HS for inhibiting the protease, BACE-1. The complex variations in activity with structural changes support the view that important functional information is embedded in HS sequences. Furthermore, the most active derivative provides an attractive lead compound for the preparation of more potent compounds, which may find use as a therapeutic agent for Alzheimer's disease. PMID:19904943

  13. Synthesis, Structure-Activity Relationships (SAR) and in Silico Studies of Coumarin Derivatives with Antifungal Activity

    PubMed Central

    de Araújo, Rodrigo S. A.; Guerra, Felipe Q. S.; de O. Lima, Edeltrudes; de Simone, Carlos A.; Tavares, Josean F.; Scotti, Luciana; Scotti, Marcus T.; de Aquino, Thiago M.; de Moura, Ricardo O.; Mendonça, Francisco J. B.; Barbosa-Filho, José M.

    2013-01-01

    The increased incidence of opportunistic fungal infections, associated with greater resistance to the antifungal drugs currently in use has highlighted the need for new solutions. In this study twenty four coumarin derivatives were screened in vitro for antifungal activity against strains of Aspergillus. Some of the compounds exhibited significant antifungal activity with MICs values ranging between 16 and 32 μg/mL. The structure-activity relationships (SAR) study demonstrated that O-substitutions are essential for antifungal activity. It also showed that the presence of a short aliphatic chain and/or electron withdrawing groups (NO2 and/or acetate) favor activity. These findings were confirmed using density functional theory (DFT), when calculating the LUMO density. In Principal Component Analysis (PCA), two significant principal components (PCs) explained more than 60% of the total variance. The best Partial Least Squares Regression (PLS) model showed an r2 of 0.86 and q2cv of 0.64 corroborating the SAR observations as well as demonstrating a greater probe N1 interaction for active compounds. Descriptors generated by TIP correlogram demonstrated the importance of the molecular shape for antifungal activity. PMID:23306152

  14. Structure-Activity Relationships of the Human Immunodeficiency Virus Type 1 Maturation Inhibitor PF-46396

    PubMed Central

    Murgatroyd, Christopher; Pirrie, Lisa; Tran, Fanny; Smith, Terry K.

    2016-01-01

    ABSTRACT HIV-1 maturation inhibitors are a novel class of antiretroviral compounds that consist of two structurally distinct chemical classes: betulinic acid derivatives and the pyridone-based compound PF-46396. It is currently believed that both classes act by similar modes of action to generate aberrant noninfectious particles via inhibition of CA-SP1 cleavage during Gag proteolytic processing. In this study, we utilized a series of novel analogues with decreasing similarity to PF-46396 to determine the chemical groups within PF-46396 that contribute to antiviral activity, Gag binding, and the relationship between these essential properties. A spectrum of antiviral activity (active, intermediate, and inactive) was observed across the analogue series with respect to CA-SP1 cleavage and HIV-1 (NL4-3) replication kinetics in Jurkat T cells. We demonstrate that selected inactive analogues are incorporated into wild-type (WT) immature particles and that one inactive analogue is capable of interfering with PF-46396 inhibition of CA-SP1 cleavage. Mutations that confer PF-46396 resistance can impose a defective phenotype on HIV-1 that can be rescued in a compound-dependent manner. Some inactive analogues retained the capacity to rescue PF-46396-dependent mutants (SP1-A3V, SP1-A3T, and CA-P157S), implying that they can also interact with mutant Gag. The structure-activity relationships observed in this study demonstrate that (i) the tert-butyl group is essential for antiviral activity but is not an absolute requirement for Gag binding, (ii) the trifluoromethyl group is optimal but not essential for antiviral activity, and (iii) the 2-aminoindan group is important for antiviral activity and Gag binding but is not essential, as its replacement is tolerated. IMPORTANCE Combinations of antiretroviral drugs successfully treat HIV/AIDS patients; however, drug resistance problems make the development of new mechanistic drug classes an ongoing priority. HIV-1 maturation

  15. Fundamental Structure-Activity Relationships of Titanium Dioxide-Based Photocatalysts

    NASA Astrophysics Data System (ADS)

    Roberts, Charles A.

    Heterogeneous photocatalysis has been identified as a means of using renewable solar energy to produce the sustainable, non-carbon fuel H 2 and a variety of useful chemical intermediates. Currently, however, heterogeneous photocatalytic reactions are too inefficient to be industrially relevant and a deeper understanding of the effect of fundamental photocatalytic material properties on photoactivity is needed to further enhance the yields of desired products. In the general field of heterogeneous catalysis, structure-activity relationships aid in the rational design of improved catalysts and this ideology was applied to photocatalytic reactions over TiO2 based photocatalysts and model supported TiO2/SiO2 catalysts in this study. The model supported TiO2/SiO2 catalysts contain well-defined TiOx nanodomain structures that vary in domain size and electronic structure and greatly facilitate the determination of structure-photoactivity relationships. These catalysts were used in reactor studies during photocatalytic water splitting and cyclohexane photo-oxidation, and were monitored for production of H2 and cyclohexanone, respectively. It was found that for both reactions the trend in photoactivity for the TiOx nanodomains proceeded as: pure TiO2 (anatase) (24 nm) > TiO2 (anatase) nanoparticles (4--11 nm) > polymeric surface TiO5 (˜1 nm) > surface isolated TiO4 (˜0.4 nm). Photoluminescence (PL) spectroscopy was employed to yield insight into how exciton generation and recombination are related to TiOx domain size and, thus, to the photoactivity of the examined reactions. Transient PL decay studies determined that the larger bulk structure found in TiO 2 (anatase) nanoparticles (NPs) acts as a reservoir for excitons exhibiting slow recombination kinetics, which have an increased opportunity to participate in photochemistry at the surface active sites. The reactions were also studied using in situ attenuated total reflectance (ATR) Fourier transform infrared

  16. Relocating alcohol advertising research: examining socially mediated relationships with alcohol.

    PubMed

    Cherrington, Jane; Chamberlain, Kerry; Grixti, Joe

    2006-03-01

    This article reviews, critiques and politicises the positivist approaches that presently dominate alcohol advertising health research, and considers the benefits of a culturalist alternative. Positivist research in this area is identified as: (1) atheoretical and methods-driven; (2) restricted in focus, leaving critical issues unconsidered; and (3) inappropriately conceptualizing the 'normal' drinking person as rational and safe. The culturist alternative proposed is argued to present a more adequate framework, which can include and address problematic issues that are presently excluded, including: the pleasures associated with alcohol use, the involvements of 'normal' people in problem drinking, the inadequacy of present risk categories and the complexities of wider mediatory processes about alcohol in society. We argue for the adoption of more informed, culturalist approaches to alcohol advertising research. PMID:16464920

  17. Three dimensional quantitative structure-activity relationships of sulfonamides binding monoclonal antibody by comparative molecular field analysis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The three-dimensional quantitative structure-activity relationship (3D-QSAR) model of sulfonamide analogs, binding a monoclonal antibody (MabSMR) produced against sulfamerazine was carried out by comparative molecular field analysis (CoMFA). The affinities of MabSMR, expressed as Log10IC50, for 17 ...

  18. Synthesis and structure-activity relationships of novel furazan-3,4-diamide analogs as potent anti-cancer agents.

    PubMed

    Li, Wen-Shan; More, Shivaji V; Wang, Chie-Hong; Jen, Ya Ching; Yao, Ching-Fa; Wang, Tein-Fu; Hung, Chin-Chun; Jao, Shu-Chuan

    2010-02-01

    This study describes the synthesis and structure-activity relationships of a series of furazan-3,4-diamide analogs. 1,2,5-Oxadiazole ring and electron-withdrawing substituent on the phenyl ring are proposed to be the important elements which contribute to a significant extent maximal potency of anti-proliferation effect. PMID:20022505

  19. Structure Activity Relationships of α-L-LNA Modified Phosphorothioate Gapmer Antisense Oligonucleotides in Animals.

    PubMed

    Seth, Punit P; Jazayeri, Ali; Yu, Jeff; Allerson, Charles R; Bhat, Balkrishen; Swayze, Eric E

    2012-01-01

    We report the structure activity relationships of short 14-mer phosphorothioate gapmer antisense oligonucleotides (ASOs) modified with α-L-locked nucleic acid (LNA) and related modifications targeting phosphatase and tensin homologue (PTEN) messenger RNA in mice. α-L-LNA represents the α-anomer of enantio-LNA and modified oligonucleotides show LNA like binding affinity for complementary RNA. In contrast to sequence matched LNA gapmer ASOs which showed elevations in plasma alanine aminotransferase (ALT) levels indicative of hepatotoxicity, gapmer ASOs modified with α-L-LNA and related analogs in the flanks showed potent downregulation of PTEN messenger RNA in liver tissue without producing elevations in plasma ALT levels. However, the α-L-LNA ASO showed a moderate dose-dependent increase in liver and spleen weights suggesting a higher propensity for immune stimulation. Interestingly, replacing α-L-LNA nucleotides in the 3'- and 5'-flanks with R-5'-Me-α-L-LNA but not R-6'-Me- or 3'-Me-α-L-LNA nucleotides, reversed the drug induced increase in organ weights. Examination of structural models of dinucleotide units suggested that the 5'-Me group increases steric bulk in close proximity to the phosphorothioate backbone or produces subtle changes in the backbone conformation which could interfere with recognition of the ASO by putative immune receptors. Our data suggests that introducing steric bulk at the 5'-position of the sugar-phosphate backbone could be a general strategy to mitigate the immunostimulatory profile of oligonucleotide drugs. In a clinical setting, proinflammatory effects manifest themselves as injection site reactions and flu-like symptoms. Thus, a mitigation of these effects could increase patient comfort and compliance when treated with ASOs.Molecular Therapy - Nucleic Acids (2012) 1, e47; doi:10.1038/mtna.2012.34; published online 18 September 2012. PMID:23344239

  20. Quantitative structure activity relationship and risk analysis of some pesticides in the goat milk

    PubMed Central

    2013-01-01

    The detection and quantification of different pesticides in the goat milk samples collected from different localities of Faisalabad, Pakistan was performed by HPLC using solid phase microextraction. The analysis showed that about 50% milk samples were contaminated with pesticides. The mean±SEM levels (ppm) of cyhalothrin, endosulfan, chlorpyrifos and cypermethrin were 0.34±0.007, 0.063±0.002, 0.034±0.002 and 0.092±0.002, respectively; whereas, methyl parathion was not detected in any of the analyzed samples. Quantitative structure activity relationship (QSAR) models were suggested to predict the residues of unknown pesticides in the goat milk using their known physicochemical characteristics including molecular weight (MW), melting point (MP), and log octanol to water partition coefficient (Ko/w) in relation to the characteristics such as pH, % fat, specific gravity and refractive index of goat milk. The analysis revealed good correlation coefficient (R2 = 0.985) for goat QSAR model. The coefficients for Ko/w and refractive index for the studied pesticides were higher in goat milk. This suggests that these are better determinants for pesticide residue prediction in the milk of these animals. Based upon the determined pesticide residues and their provisional tolerable daily intakes, risk analysis was also conducted which showed that daily intake levels of pesticide residues including cyhalothrin, chlorpyrifos and cypermethrin in present study are 2.68, 5.19 and 2.71 times higher, respectively in the goat milk. This intake of pesticide contaminated milk might pose health hazards to humans in this locality. PMID:23369514

  1. Structure-Activity Relationships of Constrained Phenylethylamine Ligands for the Serotonin 5-HT2 Receptors

    PubMed Central

    Isberg, Vignir; Paine, James; Leth-Petersen, Sebastian; Kristensen, Jesper L.; Gloriam, David E.

    2013-01-01

    Serotonergic ligands have proven effective drugs in the treatment of migraine, pain, obesity, and a wide range of psychiatric and neurological disorders. There is a clinical need for more highly 5-HT2 receptor subtype-selective ligands and the most attention has been given to the phenethylamine class. Conformationally constrained phenethylamine analogs have demonstrated that for optimal activity the free lone pair electrons of the 2-oxygen must be oriented syn and the 5-oxygen lone pairs anti relative to the ethylamine moiety. Also the ethyl linker has been constrained providing information about the bioactive conformation of the amine functionality. However, combined 1,2-constriction by cyclization has only been tested with one compound. Here, we present three new 1,2-cyclized phenylethylamines, 9–11, and describe their synthetic routes. Ligand docking in the 5-HT2B crystal structure showed that the 1,2-heterocyclized compounds can be accommodated in the binding site. Conformational analysis showed that 11 can only bind in a higher-energy conformation, which would explain its absent or low affinity. The amine and 2-oxygen interactions with D3.32 and S3.36, respectively, can form but shift the placement of the core scaffold. The constraints in 9–11 resulted in docking poses with the 4-bromine in closer vicinity to 5.46, which is polar only in the human 5-HT2A subtype, for which 9–11 have the lowest affinity. The new ligands, conformational analysis and docking expand the structure-activity relationships of constrained phenethylamines and contributes towards the development of 5-HT2 receptor subtype-selective ligands. PMID:24244317

  2. Quantitative structure-activity relationships (QSARs) for the transformation of organic micropollutants during oxidative water treatment.

    PubMed

    Lee, Yunho; von Gunten, Urs

    2012-12-01

    Various oxidants such as chlorine, chlorine dioxide, ferrate(VI), ozone, and hydroxyl radicals can be applied for eliminating organic micropollutant by oxidative transformation during water treatment in systems such as drinking water, wastewater, and water reuse. Over the last decades, many second-order rate constants (k) have been determined for the reaction of these oxidants with model compounds and micropollutants. Good correlations (quantitative structure-activity relationships or QSARs) are often found between the k-values for an oxidation reaction of closely related compounds (i.e. having a common organic functional group) and substituent descriptor variables such as Hammett or Taft sigma constants. In this study, we developed QSARs for the oxidation of organic and some inorganic compounds and organic micropollutants transformation during oxidative water treatment. A number of 18 QSARs were developed based on overall 412 k-values for the reaction of chlorine, chlorine dioxide, ferrate, and ozone with organic compounds containing electron-rich moieties such as phenols, anilines, olefins, and amines. On average, 303 out of 412 (74%) k-values were predicted by these QSARs within a factor of 1/3-3 compared to the measured values. For HO(·) reactions, some principles and estimation methods of k-values (e.g. the Group Contribution Method) are discussed. The developed QSARs and the Group Contribution Method could be used to predict the k-values for various emerging organic micropollutants. As a demonstration, 39 out of 45 (87%) predicted k-values were found within a factor 1/3-3 compared to the measured values for the selected emerging micropollutants. Finally, it is discussed how the uncertainty in the predicted k-values using the QSARs affects the accuracy of prediction for micropollutant elimination during oxidative water treatment. PMID:22939392

  3. Quantitative Structure--Activity Relationship (QSAR) for the Oxidation of Trace Organic Contaminants by Sulfate Radical.

    PubMed

    Xiao, Ruiyang; Ye, Tiantian; Wei, Zongsu; Luo, Shuang; Yang, Zhihui; Spinney, Richard

    2015-11-17

    The sulfate radical anion (SO4•–) based oxidation of trace organic contaminants (TrOCs) has recently received great attention due to its high reactivity and low selectivity. In this study, a meta-analysis was conducted to better understand the role of functional groups on the reactivity between SO4•– and TrOCs. The results indicate that compounds in which electron transfer and addition channels dominate tend to exhibit a faster second-order rate constants (kSO4•–) than that of H–atom abstraction, corroborating the SO4•– reactivity and mechanisms observed in the individual studies. Then, a quantitative structure activity relationship (QSAR) model was developed using a sequential approach with constitutional, geometrical, electrostatic, and quantum chemical descriptors. Two descriptors, ELUMO and EHOMO energy gap (ELUMO–EHOMO) and the ratio of oxygen atoms to carbon atoms (#O:C), were found to mechanistically and statistically affect kSO4•– to a great extent with the standardized QSAR model: ln kSO4•– = 26.8–3.97 × #O:C – 0.746 × (ELUMO–EHOMO). In addition, the correlation analysis indicates that there is no dominant reaction channel for SO4•– reactions with various structurally diverse compounds. Our QSAR model provides a robust predictive tool for estimating emerging micropollutants removal using SO4•– during wastewater treatment processes. PMID:26451961

  4. Quantitative structure-activity relationships (QSARs) using the novel marine algal toxicity data of phenols.

    PubMed

    Ertürk, M Doğa; Saçan, Melek Türker; Novic, Marjana; Minovski, Nikola

    2012-09-01

    The present study reports for the first time in its entirety the toxicity of 30 phenolic compounds to marine alga Dunaliella tertiolecta. Toxicity of polar narcotics and respiratory uncouplers was strongly correlated to hydrophobicity as described by the logarithm of the octanol/water partition coefficient (Log P). Compounds expected to act by more reactive mechanisms, particularly hydroquinones, were shown to have toxicity in excess of that predicted by Log P. A quality quantitative structure-activity relationship (QSAR) was obtained with Log P and a 2D autocorrelation descriptor weighted by atomic polarizability (MATS3p) only after the removal of hydroquinones from the data set. In an attempt to model the whole data set including hydroquinones, 3D descriptors were included in the modeling process and three quality QSARs were developed using multiple linear regression (MLR). One of the most significant results of the present study was the superior performance of the consensus MLR model, obtained by averaging the predictions from each individual linear model, which provided excellent prediction accuracy for the test set (Q(test)²=0.94). The four-parameter Counter Propagation Artificial Neural Network (CP ANN) model, which was constructed using four out of six descriptors that appeared in the linear models, also provided an excellent external predictivity (Q(test)²=0.93). The proposed algal QSARs were further tested in their predictivity using an external set comprising toxicity data of 44 chemicals on freshwater alga Pseudokirchneriella subcapitata. The two-parameter global model employing a 3D descriptor (Mor24m) and a charge-related descriptor (C(ortho)) not only had high external predictivity (Q(ext)²=0.74), but it also had excellent external data set coverage (%97). PMID:23085159

  5. Structure-Activity Relationship of Benzophenanthridine Alkaloids from Zanthoxylum rhoifolium Having Antimicrobial Activity

    PubMed Central

    Tavares, Luciana de C.; Zanon, Graciane; Weber, Andréia D.; Neto, Alexandre T.; Mostardeiro, Clarice P.; Da Cruz, Ivana B. M.; Oliveira, Raul M.; Ilha, Vinicius; Dalcol, Ionara I.; Morel, Ademir F.

    2014-01-01

    Zanthoxylum rhoifolium (Rutaceae) is a plant alkaloid that grows in South America and has been used in Brazilian traditional medicine for the treatment of different health problems. The present study was designed to evaluate the antimicrobial activity of the steam bark crude methanol extract, fractions, and pure alkaloids of Z. rhoifolium. Its stem bark extracts exhibited a broad spectrum of antimicrobial activity, ranging from 12.5 to 100 µg/mL using bioautography method, and from 125 to 500 µg/mL in the microdilution bioassay. From the dichloromethane basic fraction, three furoquinoline alkaloids (1–3), and nine benzophenanthridine alkaloids (4–12) were isolated and the antimicrobial activity of the benzophenanthridine alkaloids is discussed in terms of structure-activity relationships. The alkaloid with the widest spectrum of activity was chelerythrine (10), followed by avicine (12) and dihydrochelerythrine (4). The minimal inhibitory concentrations of chelerythrine, of 1.50 µg/mL for all bacteria tested, and between 3.12 and 6.25 µg/mL for the yeast tested, show this compound to be a more powerful antimicrobial agent when compared with the other active alkaloids isolated from Z. rhoifolium. To verify the potential importance of the methylenedioxy group (ring A) of these alkaloids, chelerythrine was selected to represent the remainder of the benzophenanthridine alkaloids isolated in this work and was subjected to a demethylation reaction giving derivative 14. Compared to chelerythrine, the derivative (14) was less active against the tested bacteria and fungi. Kinetic measurements of the bacteriolytic activities of chelerythrine against the bacteria Bacillus subtilis (Gram-positive) and Escherichia coli (Gram-negative) were determined by optical density based on real time assay, suggesting that its mechanism of action is not bacteriolytic. The present study did not detect hemolytic effects of chelerythrine on erythrocytes and found a protective effect

  6. Quantitative structure activity relationship and risk analysis of some pesticides in the goat milk.

    PubMed

    Muhammad, Faqir; Awais, Mian Muhammad; Akhtar, Masood; Anwar, Muhammad Irfan

    2013-01-01

    The detection and quantification of different pesticides in the goat milk samples collected from different localities of Faisalabad, Pakistan was performed by HPLC using solid phase microextraction. The analysis showed that about 50% milk samples were contaminated with pesticides. The mean±SEM levels (ppm) of cyhalothrin, endosulfan, chlorpyrifos and cypermethrin were 0.34±0.007, 0.063±0.002, 0.034±0.002 and 0.092±0.002, respectively; whereas, methyl parathion was not detected in any of the analyzed samples. Quantitative structure activity relationship (QSAR) models were suggested to predict the residues of unknown pesticides in the goat milk using their known physicochemical characteristics including molecular weight (MW), melting point (MP), and log octanol to water partition coefficient (Ko/w) in relation to the characteristics such as pH, % fat, specific gravity and refractive index of goat milk. The analysis revealed good correlation coefficient (R2 = 0.985) for goat QSAR model. The coefficients for Ko/w and refractive index for the studied pesticides were higher in goat milk. This suggests that these are better determinants for pesticide residue prediction in the milk of these animals. Based upon the determined pesticide residues and their provisional tolerable daily intakes, risk analysis was also conducted which showed that daily intake levels of pesticide residues including cyhalothrin, chlorpyrifos and cypermethrin in present study are 2.68, 5.19 and 2.71 times higher, respectively in the goat milk. This intake of pesticide contaminated milk might pose health hazards to humans in this locality. PMID:23369514

  7. Molecular characterization of the receptor binding structure-activity relationships of influenza B virus hemagglutinin.

    PubMed

    Carbone, V; Kim, H; Huang, J X; Baker, M A; Ong, C; Cooper, M A; Li, J; Rockman, S; Velkov, T

    2013-01-01

    Selectivity of α2,6-linked human-like receptors by B hemagglutinin (HA) is yet to be fully understood. This study integrates binding data with structure-recognition models to examine the impact of regional-specific sequence variations within the receptor-binding pocket on selectivity and structure activity relationships (SAR). The receptor-binding selectivity of influenza B HAs corresponding to either B/Victoria/2/1987 or the B/Yamagata/16/88 lineages was examined using surface plasmon resonance, solid-phase ELISA and gel-capture assays. Our SAR data showed that the presence of asialyl sugar units is the main determinant of receptor preference of α2,6 versus α2,3 receptor binding. Changes to the type of sialyl-glycan linkage present on receptors exhibit only a minor effect upon binding affinity. Homology-based structural models revealed that structural properties within the HA pocket, such as a glyco-conjugate at Asn194 on the 190-helix, sterically interfere with binding to avian receptor analogs by blocking the exit path of the asialyl sugars. Similarly, naturally occurring substitutions in the C-terminal region of the 190-helix and near the N-terminal end of the 140-loop narrows the horizontal borders of the binding pocket, which restricts access of the avian receptor analog LSTa. This study helps bridge the gap between ligand structure and receptor recognition for influenza B HA; and provides a consensus SAR model for the binding of human and avian receptor analogs to influenza B HA. PMID:24020757

  8. Structure-activity relationship of synthetic branched-chain distearoylglycerol (distearin) as protein kinase C activators

    SciTech Connect

    Zhou, Qingzhong; Raynor, R.L.; Wood, M.G. Jr.; Menger, F.M.; Kuo, J.F. )

    1988-09-20

    Several representative branched-chain analogues of distearin (DS) were synthesized and tested for their abilities to activate protein kinase C (PKC) and to compete for the binding of ({sup 3}H)phorbol 12,13-dibutyrate (PDBu) to the enzyme. Substitutions of stearoyl moieties at sn-1 and sn-2 with 8-methylstearate decreased activities on these parameters, relative to those of the parental diacylglycerol DS, a weak PKC activator. Substitutions with 8-butyl, 4-butyl, or 8-phenyl derivatives, on the other hand, increased activities of the resulting analogues to levels comparable to those seen for diolein (DO), a diacylglycerol prototype shown to be a potent PKC activator. Kinetic analysis indicated that 8-methyldistearin (8-MeDS) acted by decreasing, whereas 8-butyldistearin (8-BuDS) and 8-phenyldistearin (8-PhDS) acted by increasing, the affinities of PKC for phosphatidylserine (PS, a phospholipid cofactor) and Ca{sup 2+} compared to the values seen in the absence or presence of DS. The stimulatory effect of 8-BuDS and 8-PhDS on PKC, as DO, was additive to that of 1,2-(8-butyl)distearoylphosphatidylcholine (1,2(8-Bu)DSPC) and, moreover, they abolished the marked inhibition of the enzyme activity caused by high concentrations of 1,2(8-Bu)DSPC. The present findings demonstrated a structure-activity relationship of the branched-chain DS analogues in the regulation of PKC, perhaps related to their abilities to specifically modify interactions of PKC with PS and/or Ca{sup 2+} critically involved in enzyme activation/inactivation.

  9. Toward a class-independent quantitative structure--activity relationship model for uncouplers of oxidative phosphorylation.

    PubMed

    Spycher, Simon; Smejtek, Pavel; Netzeva, Tatiana I; Escher, Beate I

    2008-04-01

    A mechanistically based quantitative structure-activity relationship (QSAR) for the uncoupling activity of weak organic acids has been derived. The analysis of earlier experimental studies suggested that the limiting step in the uncoupling process is the rate with which anions can cross the membrane and that this rate is determined by the height of the energy barrier encountered in the hydrophobic membrane core. We use this mechanistic understanding to develop a predictive model for uncoupling. The translocation rate constants of anions correlate well with the free energy difference between the energy well and the energy barrier, Delta G well-barrier,A (-) , in the membrane calculated by a novel approach to describe internal partitioning in the membrane. An existing data set of 21 phenols measured in an in vitro test system specific for uncouplers was extended by 14 highly diverse compounds. A simple regression model based on the experimental membrane-water partition coefficient and Delta G well-barrier,A (-) showed good predictive power and had meaningful regression coefficients. To establish uncoupler QSARs independent of chemical class, it is necessary to calculate the descriptors for the charged species, as the analogous descriptors of the neutral species showed almost no correlation with the translocation rate constants of anions. The substitution of experimental with calculated partition coefficients resulted in a decrease of the model fit. A particular strength of the current model is the accurate calculation of excess toxicity, which makes it a suitable tool for database screening. The applicability domain, limitations of the model, and ideas for future research are critically discussed. PMID:18358007

  10. Quantitative structure-activity relationships for organophosphates binding to trypsin and chymotrypsin.

    PubMed

    Ruark, Christopher D; Hack, C Eric; Robinson, Peter J; Gearhart, Jeffery M

    2011-01-01

    Organophosphate (OP) nerve agents such as sarin, soman, tabun, and O-ethyl S-[2-(diisopropylamino) ethyl] methylphosphonothioate (VX) do not react solely with acetylcholinesterase (AChE). Evidence suggests that cholinergic-independent pathways over a wide range are also targeted, including serine proteases. These proteases comprise nearly one-third of all known proteases and play major roles in synaptic plasticity, learning, memory, neuroprotection, wound healing, cell signaling, inflammation, blood coagulation, and protein processing. Inhibition of these proteases by OP was found to exert a wide range of noncholinergic effects depending on the type of OP, the dose, and the duration of exposure. Consequently, in order to understand these differences, in silico biologically based dose-response and quantitative structure-activity relationship (QSAR) methodologies need to be integrated. Here, QSAR were used to predict OP bimolecular rate constants for trypsin and α-chymotrypsin. A heuristic regression of over 500 topological/constitutional, geometric, thermodynamic, electrostatic, and quantum mechanical descriptors, using the software Ampac 8.0 and Codessa 2.51 (SemiChem, Inc., Shawnee, KS), was developed to obtain statistically verified equations for the models. General models, using all data subsets, resulted in R(2) values of .94 and .92 and leave-one-out Q(2) values of 0.9 and 0.87 for trypsin and α-chymotrypsin. To validate the general model, training sets were split into independent subsets for test set evaluation. A y-randomization procedure, used to estimate chance correlation, was performed 10,000 times, resulting in mean R(2) values of .24 and .3 for trypsin and α-chymotrypsin. The results show that these models are highly predictive and capable of delineating the complex mechanism of action between OP and serine proteases, and ultimately, by applying this approach to other OP enzyme reactions such as AChE, facilitate the development of biologically based

  11. Structure-activity Relationships of Peptidomimetics that Inhibit PPI of HER2-HER3

    PubMed Central

    Kanthala, Shanthi; Gauthier, Ted; Satyanarayanajois, Seetharama

    2014-01-01

    Human epidermal growth factor receptor-2 (HER2) is a tyrosine kinase family protein receptor that is known to undergo heterodimerization with other members of the family of epidermal growth factor receptors (EGFR) for cell signaling. Overexpression of HER2 and deregulation of signaling has implications in breast, ovarian, and lung cancers. We have designed several peptidomimetics to block the HER2-mediated dimerization, resulting in antiproliferative activity for cancer cells. In the present work we have investigated the structure-activity relationships of peptidomimetic analogs of compound 5. Compound 5 was conformationally constrained by N- and C-terminal modification and cyclization as well as by substitution with D-amino acids at the N-and C-termini. Among the compounds studied in this work, a peptidomimetic compound 21 with D-amino acid substitution and its N- and C-termini capped with acetyl and amide functional groups and a reversed sequence compared to that of compound 5 exhibited better antiproliferative activity in HER2-overexpressed breast, ovarian, and lung cancer cell lines. Compound 21 was further evaluated for its protein-protein interaction (PPI) inhibition ability using enzyme fragment complementation (EFC) assay, proximity ligation assay (PLA), and Western blot analysis. Results suggested that compound 21 is able to block HER2:HER3 interaction and inhibit phosphorylation of the kinase domain of HER2. The mode of binding of compound 21 to HER2 protein was modeled using a docking method. Compound 21 seems to bind to domain IV of HER2 near the PPI site of EGFR:HER2 and HER:HER3 and inhibit PPI. PMID:24222531

  12. Design and prediction of new acetylcholinesterase inhibitor via quantitative structure activity relationship of huprines derivatives.

    PubMed

    Zhang, Shuqun; Hou, Bo; Yang, Huaiyu; Zuo, Zhili

    2016-05-01

    Acetylcholinesterase (AChE) is an important enzyme in the pathogenesis of Alzheimer's disease (AD). Comparative quantitative structure-activity relationship (QSAR) analyses on some huprines inhibitors against AChE were carried out using comparative molecular field analysis (CoMFA), comparative molecular similarity indices analysis (CoMSIA), and hologram QSAR (HQSAR) methods. Three highly predictive QSAR models were constructed successfully based on the training set. The CoMFA, CoMSIA, and HQSAR models have values of r (2) = 0.988, q (2) = 0.757, ONC = 6; r (2) = 0.966, q (2) = 0.645, ONC = 5; and r (2) = 0.957, q (2) = 0.736, ONC = 6. The predictabilities were validated using an external test sets, and the predictive r (2) values obtained by the three models were 0.984, 0.973, and 0.783, respectively. The analysis was performed by combining the CoMFA and CoMSIA field distributions with the active sites of the AChE to further understand the vital interactions between huprines and the protease. On the basis of the QSAR study, 14 new potent molecules have been designed and six of them are predicted to be more active than the best active compound 24 described in the literature. The final QSAR models could be helpful in design and development of novel active AChE inhibitors. PMID:26832327

  13. Synthesis and structure-activity relationships of potent antitumor active quinoline and naphthyridine derivatives.

    PubMed

    Srivastava, Sanjay K; Jha, Amrita; Agarwal, Shiv K; Mukherjee, Rama; Burman, Anand C

    2007-11-01

    The disease of cancer has been ranked second after cardiovascular diseases and plant-derived molecules have played an important role for the treatment of cancer. Nine cytotoxic plant-derived molecules such as vinblastine, vincristine, navelbine, etoposide, teniposide, taxol, taxotere, topotecan and irinotecan have been approved as anticancer drugs. Recently, epothilones are being emerging as future potential anti-tumor agents. However, targeted cancer therapy has now been rapidly expanding and small organic molecules are being exploited for this purpose. Amongst target specific small organic molecules, quinazoline was found as one of the most successful chemical class in cancer chemotherapy as three drugs namely Gefitinib, Erlotinib and Canertinib belong to this series. Now, quinazoline related chemical classes such as quinolines and naphthyridines are being exploited in cancer chemotherapy and a number of molecules such as compounds EKB-569 (52), HKI-272 (78) and SNS-595 (127a) are in different phases of clinical trials. This review presents the synthesis of quinolines and naphthyridines derivatives, screened for anticancer activity since year 2000. The synthesis of most potent derivatives in each prototype has been delineated. A brief structure activity relationship for each prototype has also been discussed. It has been observed that aniline group at C-4, aminoacrylamide substituents at C-6, cyano group at C-3 and alkoxy groups at C-7 in the quinoline ring play an important role for optimal activity. While aminopyrrolidine functionality at C-7, 2'-thiazolyl at N-1 and carboxy group at C-3 in 1,8-naphthyridine ring are essential for eliciting the cytotoxicity. This review would help the medicinal chemist to design and synthesize molecules for targeted cancer chemotherapy. PMID:18045063

  14. Multiobjective optimization in quantitative structure-activity relationships: deriving accurate and interpretable QSARs.

    PubMed

    Nicolotti, Orazio; Gillet, Valerie J; Fleming, Peter J; Green, Darren V S

    2002-11-01

    Deriving quantitative structure-activity relationship (QSAR) models that are accurate, reliable, and easily interpretable is a difficult task. In this study, two new methods have been developed that aim to find useful QSAR models that represent an appropriate balance between model accuracy and complexity. Both methods are based on genetic programming (GP). The first method, referred to as genetic QSAR (or GPQSAR), uses a penalty function to control model complexity. GPQSAR is designed to derive a single linear model that represents an appropriate balance between the variance and the number of descriptors selected for the model. The second method, referred to as multiobjective genetic QSAR (MoQSAR), is based on multiobjective GP and represents a new way of thinking of QSAR. Specifically, QSAR is considered as a multiobjective optimization problem that comprises a number of competitive objectives. Typical objectives include model fitting, the total number of terms, and the occurrence of nonlinear terms. MoQSAR results in a family of equivalent QSAR models where each QSAR represents a different tradeoff in the objectives. A practical consideration often overlooked in QSAR studies is the need for the model to promote an understanding of the biochemical response under investigation. To accomplish this, chemically intuitive descriptors are needed but do not always give rise to statistically robust models. This problem is addressed by the addition of a further objective, called chemical desirability, that aims to reward models that consist of descriptors that are easily interpretable by chemists. GPQSAR and MoQSAR have been tested on various data sets including the Selwood data set and two different solubility data sets. The study demonstrates that the MoQSAR method is able to find models that are at least as good as models derived using standard statistical approaches and also yields models that allow a medicinal chemist to trade statistical robustness for chemical

  15. Inhibition of Angiotensin-Converting Enzyme Activity by Flavonoids: Structure-Activity Relationship Studies

    PubMed Central

    Guerrero, Ligia; Castillo, Julián; Quiñones, Mar; Garcia-Vallvé, Santiago; Arola, Lluis; Pujadas, Gerard; Muguerza, Begoña

    2012-01-01

    Previous studies have demonstrated that certain flavonoids can have an inhibitory effect on angiotensin-converting enzyme (ACE) activity, which plays a key role in the regulation of arterial blood pressure. In the present study, 17 flavonoids belonging to five structural subtypes were evaluated in vitro for their ability to inhibit ACE in order to establish the structural basis of their bioactivity. The ACE inhibitory (ACEI) activity of these 17 flavonoids was determined by fluorimetric method at two concentrations (500 µM and 100 µM). Their inhibitory potencies ranged from 17 to 95% at 500 µM and from 0 to 57% at 100 µM. In both cases, the highest ACEI activity was obtained for luteolin. Following the determination of ACEI activity, the flavonoids with higher ACEI activity (i.e., ACEI >60% at 500 µM) were selected for further IC50 determination. The IC50 values for luteolin, quercetin, rutin, kaempferol, rhoifolin and apigenin K were 23, 43, 64, 178, 183 and 196 µM, respectively. Our results suggest that flavonoids are an excellent source of functional antihypertensive products. Furthermore, our structure-activity relationship studies show that the combination of sub-structures on the flavonoid skeleton that increase ACEI activity is made up of the following elements: (a) the catechol group in the B-ring, (b) the double bond between C2 and C3 at the C-ring, and (c) the cetone group in C4 at the C-ring. Protein-ligand docking studies are used to understand the molecular basis for these results. PMID:23185345

  16. Disturbed Sleep and Its Relationship to Alcohol Use

    PubMed Central

    Stein, Michael D.; Friedmann, Peter D.

    2009-01-01

    Study Objectives To review evidence of an association between disturbed sleep and alcohol use. Design We searched MEDLINE, PSYCHINFO, ETOH, BIBLIOSLEEP and the Rutgers Alcohol Studies databases between January 1966 and August 2002. Search terms included alcohol-related disorders or alcoholism in combination with sleep, sleep initiation and maintenance disorders, or sleep apnea syndromes. The search produced over 440 citations. We reviewed 107 relevant articles, of which 60 included quantitative measures of both alcohol use and sleep. Measurements and Results Behavioral studies suggest that up to 2 to 3 standard drinks before bedtime initially promotes sleep, but these effects diminish in as few as 3 days of continued use. Clinical investigations support a relationship between sleep disturbance and alcohol use, but variability in the definition and measurement of these domains and a preponderance of cross-sectional studies make uncertain the strength and direction of the association. Conclusions The association of insomnia with alcohol use disorders suggests that the clinical evaluation of patients with sleep problems should include a careful assessment of alcohol use. Future studies of this relationship should employ prospective designs with standardized, validated measures of both sleep and alcohol use. Rigorous treatment studies for chronic insomnia in alcohol dependent patients are also needed. PMID:16492658

  17. Aquatic toxicity of acrylates and methacrylates: quantitative structure-activity relationships based on Kow and LC50

    SciTech Connect

    Reinert, K.H.

    1987-12-01

    Recent EPA scrutiny of acrylate and methacrylate monomers has resulted in restrictive consent orders and Significant New Use Rules under the Toxic Substances Control Act, based on structure-activity relationships using mouse skin painting studies. The concern is centered on human health issues regarding worker and consumer exposure. Environmental issues, such as aquatic toxicity, are still of concern. Understanding the relationships and environmental risks to aquatic organisms may improve the understanding of the potential risks to human health. This study evaluates the quantitative structure-activity relationships from measured log Kow's and log LC50's for Pimephales promelas (fathead minnow) and Carassius auratus (goldfish). Scientific support of the current regulations is also addressed. Two monomer classes were designated: acrylates and methacrylates. Spearman rank correlation and linear regression were run. Based on this study, an ecotoxicological difference exists between acrylates and methacrylates. Regulatory activities and scientific study should reflect this difference.

  18. Difficult Temperament, Parental Relationships, and Adolescent Alcohol Use Disorder Symptoms.

    ERIC Educational Resources Information Center

    Neighbors, Bryan D.; Clark, Duncan B.; Donovan, John E.; Brody, Gene H.

    2000-01-01

    Study tested the hypothesis that the quality of the parent-adolescent relationship mediates the association between difficult temperament and alcohol use disorder (AUD) symptoms. Results suggest that alcohol abuse prevention and treatment programs should consider the role of basic temperamental characteristics in pathological drinking, and the…

  19. Bringing "Booze" Back In: The Relationship between Alcohol and Homicide.

    ERIC Educational Resources Information Center

    Parker, Robert Nash

    1995-01-01

    Tested hypotheses concerning the relationship between alcohol and homicide from four major theoretical perspectives; specific predictions on the causes of types of homicide were also derived. Findings revealed that alcohol consumption rates change the way important predictors, such as poverty and deterrence, are related to specific types of…

  20. Quantitative structure-activity relationship of the curcumin-related compounds using various regression methods

    NASA Astrophysics Data System (ADS)

    Khazaei, Ardeshir; Sarmasti, Negin; Seyf, Jaber Yousefi

    2016-03-01

    Quantitative structure activity relationship were used to study a series of curcumin-related compounds with inhibitory effect on prostate cancer PC-3 cells, pancreas cancer Panc-1 cells, and colon cancer HT-29 cells. Sphere exclusion method was used to split data set in two categories of train and test set. Multiple linear regression, principal component regression and partial least squares were used as the regression methods. In other hand, to investigate the effect of feature selection methods, stepwise, Genetic algorithm, and simulated annealing were used. In two cases (PC-3 cells and Panc-1 cells), the best models were generated by a combination of multiple linear regression and stepwise (PC-3 cells: r2 = 0.86, q2 = 0.82, pred_r2 = 0.93, and r2m (test) = 0.43, Panc-1 cells: r2 = 0.85, q2 = 0.80, pred_r2 = 0.71, and r2m (test) = 0.68). For the HT-29 cells, principal component regression with stepwise (r2 = 0.69, q2 = 0.62, pred_r2 = 0.54, and r2m (test) = 0.41) is the best method. The QSAR study reveals descriptors which have crucial role in the inhibitory property of curcumin-like compounds. 6ChainCount, T_C_C_1, and T_O_O_7 are the most important descriptors that have the greatest effect. With a specific end goal to design and optimization of novel efficient curcumin-related compounds it is useful to introduce heteroatoms such as nitrogen, oxygen, and sulfur atoms in the chemical structure (reduce the contribution of T_C_C_1 descriptor) and increase the contribution of 6ChainCount and T_O_O_7 descriptors. Models can be useful in the better design of some novel curcumin-related compounds that can be used in the treatment of prostate, pancreas, and colon cancers.

  1. A Binding Site Model and Structure-Activity Relationships for the Rat A3 Adenosine Receptor

    PubMed Central

    VAN GALEN, PHILIP J. M.; VAN BERGEN, ANDREW H.; GALLO-RODRIGUEZ, CAROLA; MELMAN, NELI; OLAH, MARK E.; IJZERMAN, AD P.; STILES, GARY L.; JACOBSON, KENNETH A.

    2012-01-01

    SUMMARY A novel adenosine receptor, the A3 receptor, has recently been cloned. We have systematically investigated the hitherto largely unexplored structure-activity relationships (SARs) for binding at A3 receptors, using 125I-N6-2-(4-aminophenyl)ethyladenosine as a radioligand and membranes from Chinese hamster ovary cells stably transfected with the rat A3-cDNA. As is the case for A1 and A2a, receptors, substitutions at the N6 and 5′ positions of adenosine, the prototypic agonist ligand, may yield fairly potent compounds. However, the highest affinity and A3 selectivity is found for N6,5′-disubstituted compounds, in contrast to A1 and A2a receptors. Thus, N6-benzyladenosine-5′-N-ethylcarboxamide is highly potent (Ki, 6.8 nM) and moderately selective (13- and 14-fold versus A1 and A2a). The N6 region of the A3 receptor also appears to tolerate hydrophilic substitutions, in sharp contrast to the other subtypes. Potencies of N6,5′-disubstituted compounds in inhibition of adenylate cyclase via A3 receptors parallel their high affinity in the binding assay. None of the typical xanthine or nonxanthine (A1/A2) antagonists tested show any appreciable affinity for rat A3 receptors. 1,3-Dialkylxanthines did not antagonize the A3 agonist-induced inhibition of adenylate cyclase. A His residue in helix 6 that is absent in A3 receptors but present in A1/A2 receptors may be causal in this respect. In a molecular model for the rat A3 receptor, this mutation, together with an increased bulkiness of residues surrounding the ligand, make antagonist binding unfavorable when compared with a previously developed A1 receptor model. Second, this A3 receptor model predicted similarities with A1 and A2 receptors in the binding requirements for the ribose moiety and that xanthine-7-ribosides would bind to rat A3 receptors. This hypothesis was supported experimentally by the moderate affinity (Ki 6 μM) of 7-riboside of 1,3-dibutylxanthine, which appears to be a partial agonist at

  2. Structure Activity Relationship of Dendrimer Microbicides with Dual Action Antiviral Activity

    PubMed Central

    Tyssen, David; Henderson, Scott A.; Johnson, Adam; Sterjovski, Jasminka; Moore, Katie; La, Jennifer; Zanin, Mark; Sonza, Secondo; Karellas, Peter; Giannis, Michael P.; Krippner, Guy; Wesselingh, Steve; McCarthy, Tom; Gorry, Paul R.; Ramsland, Paul A.; Cone, Richard; Paull, Jeremy R. A.; Lewis, Gareth R.; Tachedjian, Gilda

    2010-01-01

    Background Topical microbicides, used by women to prevent the transmission of HIV and other sexually transmitted infections are urgently required. Dendrimers are highly branched nanoparticles being developed as microbicides. However, the anti-HIV and HSV structure-activity relationship of dendrimers comprising benzyhydryl amide cores and lysine branches, and a comprehensive analysis of their broad-spectrum anti-HIV activity and mechanism of action have not been published. Methods and Findings Dendrimers with optimized activity against HIV-1 and HSV-2 were identified with respect to the number of lysine branches (generations) and surface groups. Antiviral activity was determined in cell culture assays. Time-of-addition assays were performed to determine dendrimer mechanism of action. In vivo toxicity and HSV-2 inhibitory activity were evaluated in the mouse HSV-2 susceptibility model. Surface groups imparting the most potent inhibitory activity against HIV-1 and HSV-2 were naphthalene disulfonic acid (DNAA) and 3,5-disulfobenzoic acid exhibiting the greatest anionic charge and hydrophobicity of the seven surface groups tested. Their anti-HIV-1 activity did not appreciably increase beyond a second-generation dendrimer while dendrimers larger than two generations were required for potent anti-HSV-2 activity. Second (SPL7115) and fourth generation (SPL7013) DNAA dendrimers demonstrated broad-spectrum anti-HIV activity. However, SPL7013 was more active against HSV and blocking HIV-1 envelope mediated cell-to-cell fusion. SPL7013 and SPL7115 inhibited viral entry with similar potency against CXCR4-(X4) and CCR5-using (R5) HIV-1 strains. SPL7013 was not toxic and provided at least 12 h protection against HSV-2 in the mouse vagina. Conclusions Dendrimers can be engineered with optimized potency against HIV and HSV representing a unique platform for the controlled synthesis of chemically defined multivalent agents as viral entry inhibitors. SPL7013 is formulated as Viva

  3. Quantitative structure-activity relationship models of clinical pharmacokinetics: clearance and volume of distribution.

    PubMed

    Gombar, Vijay K; Hall, Stephen D

    2013-04-22

    Reliable prediction of two fundamental human pharmacokinetic (PK) parameters, systemic clearance (CL) and apparent volume of distribution (Vd), determine the size and frequency of drug dosing and are at the heart of drug discovery and development. Traditionally, estimated CL and Vd are derived from preclinical in vitro and in vivo absorption, distribution, metabolism, and excretion (ADME) measurements. In this paper, we report quantitative structure-activity relationship (QSAR) models for prediction of systemic CL and steady-state Vd (Vdss) from intravenous (iv) dosing in humans. These QSAR models avoid uncertainty associated with preclinical-to-clinical extrapolation and require two-dimensional structure drawing as the sole input. The clean, uniform training sets for these models were derived from the compilation published by Obach et al. (Drug Metab. Disp. 2008, 36, 1385-1405). Models for CL and Vdss were developed using both a support vector regression (SVR) method and a multiple linear regression (MLR) method. The SVR models employ a minimum of 2048-bit fingerprints developed in-house as structure quantifiers. The MLR models, on the other hand, are based on information-rich electro-topological states of two-atom fragments as descriptors and afford reverse QSAR (RQSAR) analysis to help model-guided, in silico modulation of structures for desired CL and Vdss. The capability of the models to predict iv CL and Vdss with acceptable accuracy was established by randomly splitting data into training and test sets. On average, for both CL and Vdss, 75% of test compounds were predicted within 2.5-fold of the value observed and 90% of test compounds were within 5.0-fold of the value observed. The performance of the final models developed from 525 compounds for CL and 569 compounds for Vdss was evaluated on an external set of 56 compounds. The predictions were either better or comparable to those predicted by other in silico models reported in the literature. To

  4. Novel Inhibitors of Influenza Virus Fusion: Structure-Activity Relationship and Interaction with the Viral Hemagglutinin▿

    PubMed Central

    Vanderlinden, Evelien; Göktaş, Fusun; Cesur, Zafer; Froeyen, Matheus; Reed, Mark L.; Russell, Charles J.; Cesur, Nesrin; Naesens, Lieve

    2010-01-01

    A new class of N-(1-thia-4-azaspiro[4.5]decan-4-yl)carboxamide inhibitors of influenza virus hemagglutinin (HA)-mediated membrane fusion that has a narrow and defined structure-activity relationship was identified. In Madin-Darby canine kidney (MDCK) cells infected with different strains of human influenza virus A/H3N2, the lead compound, 4c, displayed a 50% effective concentration of 3 to 23 μM and an antiviral selectivity index of 10. No activity was observed for A/H1N1, A/H5N1, A/H7N2, and B viruses. The activity of 4c was reduced considerably when added 30 min or later postinfection, indicating that 4c inhibits an early step in virus replication. 4c and its congeners inhibited influenza A/H3N2 virus-induced erythrocyte hemolysis at low pH. 4c-resistant virus mutants, selected in MDCK cells, contained either a single D112N change in the HA2 subunit of the viral HA or a combination of three substitutions, i.e., R220S (in HA1) and E57K (in HA2) and an A-T substitution at position 43 or 96 of HA2. The mutants showed efficiency for receptor binding and replication similar to that of wild-type virus yet displayed an increased pH of erythrocyte hemolysis. In polykaryon assays with cells expressing single-mutant HA proteins, the E57K, A96T, and D112N mutations resulted in 4c resistance, and the HA proteins containing R220S, A96T, and D112N mutations displayed an increased fusion pH. Molecular modeling identified a binding cavity for 4c involving arginine-54 and glutamic acid-57 in the HA2 subunit. Our studies with the new fusion inhibitor 4c confirm the importance of this HA region in the development of influenza virus fusion inhibitors. PMID:20181685

  5. Benzimidazole-Based Quinazolines: In Vitro Evaluation, Quantitative Structure-Activity Relationship, and Molecular Modeling as Aurora Kinase Inhibitors.

    PubMed

    Sharma, Alka; Luxami, Vijay; Saxena, Sanjai; Paul, Kamaldeep

    2016-03-01

    A series of benzimidazole-based quinazoline derivatives with different substitutions of primary and secondary amines at the C2 position (1-12) were evaluated for their Aurora kinase inhibitory activities. All compounds except for 3 and 6 showed good activity against Aurora kinase inhibitors, with IC50 values in the range of 0.035-0.532 μM. The ligand efficiency (LE) of the compounds with Aurora A kinase was also determined. The structure-activity relationship and the quantitative structure-activity relationship revealed that the Aurora inhibitory activities of these derivatives primarily depend on the different substitutions of the amine present at the C2 position of the quinazoline core. Molecular docking studies in the active binding site also provided theoretical support for the experimental biological data acquired. The current study identifies a novel class of Aurora kinase inhibitors, which can further be used for the treatment of cancer. PMID:26773437

  6. Structure-Activity Relationship Studies and Biological Characterization of Human NAD+-dependent 15-Hydroxyprostaglandin Dehydrogenase Inhibitors

    PubMed Central

    Duveau, Damien Y.; Yasgar, Adam; Wang, Yuhong; Hu, Xin; Kouznetsova, Jennifer; Brimacombe, Kyle R.; Jadhav, Ajit; Simeonov, Anton; Thomas, Craig J.; Maloney, David J.

    2014-01-01

    The structure-activity relationship (SAR) study of two chemotypes identified as inhibitors of the human NAD+-dependent 15-hydroxyprostaglandin dehydrogenase (HPGD, 15-PGDH) was conducted. Top compounds from both series displayed potent inhibition (IC50 <50 nM), demonstrate excellent selectivity towards HPGD and potently induce PGE2 production in A549 lung cancer and LNCaP prostate cancer cells. PMID:24360556

  7. How the quality of peer relationships influences college alcohol use

    PubMed Central

    BORSARI, BRIAN; CAREY, KATE B.

    2008-01-01

    Peer relationships are consistently linked to alcohol use in college students. However, this disparate literature often reveals contradictory findings regarding the precise mechanisms of peer influence. In this review, we use an organisational framework based on social learning theory (SLT) to demonstrate how the quality of peer relationships may influence personal alcohol use. We propose that the quality of peer relationships enhance the influence of social reinforcement, modelling and cognitive processes on personal alcohol use. Research indicates that the quality of peer relationships influences drinking via three pathways: the lack or breakdown of quality peer relationships, alcohol use being an integral part of peer interactions, and if peers disapprove of alcohol use or do not drink. This conceptualisation of peer influence informs the consistent finding of gender differences in college student drinking. Limitations of the reviewed research include reliance on cross-sectional surveys, self-report and homogeneous populations. Future directions for research on quality peer relationships involve detailed longitudinal assessment and the application of advanced statistical methods. PMID:16854663

  8. Marihuana, Alcohol and Tobacco: Reassessment of a Presumed Relationship.

    ERIC Educational Resources Information Center

    Dull, R. Thomas; Williams, Franklin P., III

    1981-01-01

    Concludes little relationship exists between the three substances marihuana, alcohol and tobacco. Youthful subjects tend to overestimate the relationships between the three substances and cannot be generalized to other populations. Suggests an explanation of this youthful association focuses on simultaneous experimentation rather than causal…

  9. Structure-activity relationships (SAR) and structure-kinetic relationships (SKR) of bicyclic heteroaromatic acetic acids as potent CRTh2 antagonists II: lead optimization.

    PubMed

    Alonso, Juan Antonio; Andrés, Miriam; Bravo, Mónica; Calbet, Marta; Eastwood, Paul R; Eichhorn, Peter; Esteve, Cristina; Ferrer, Manel; Gómez, Elena; González, Jacob; Mir, Marta; Moreno, Imma; Petit, Silvia; Roberts, Richard S; Sevilla, Sara; Vidal, Bernat; Vidal, Laura; Vilaseca, Pere; Zanuy, Miriam

    2014-11-01

    Extensive structure-activity relationship (SAR) and structure-kinetic relationship (SKR) studies in the bicyclic heteroaromatic series of CRTh2 antagonists led to the identification of several molecules that possessed both excellent binding and cellular potencies along with long receptor residence times. A small substituent in the bicyclic core provided an order of magnitude jump in dissociation half-lives. Selected optimized compounds demonstrated suitable pharmacokinetic profiles. PMID:25437505

  10. Structure-activity relationships of mineral dusts as heterogeneous nuclei for ammonium sulfate crystallization from supersaturated aqueous solutions.

    PubMed

    Martin, S T; Schlenker, J; Chelf, J H; Duckworth, O W

    2001-04-15

    Mineral inclusions, present in aqueous atmospheric salt droplets, regulate crystallization when relative humidity decreases by providing a surface for heterogeneous nucleation and thus reducing the critical supersaturation. Although laboratory studies have quantified these processes to some extent, the diverse atmospheric mineralogy presents more chemical systems than practically feasible for direct study. Structure--activity relationships are necessary. To that end, in the present work the interactions of ammonium sulfate with corundum, hematite, mullite, rutile, anatase, and baddeleyite were studied by diffuse reflectance fourier transform infrared spectroscopy (DRIFTS) and by epitaxial modeling. The spectroscopic results show that shifts in sulfate peak positions due to chemisorption are not a correlative indicator of the efficacy of heterogeneous nucleation. In contrast, epitaxial modeling results of unreconstructed surfaces explain the sequence of critical supersaturations for constant particle size. If validated by further work, this computer modeling method would provide an important structure--activity tool for the estimation of heterogeneous nucleation properties of the atmospheric mineralogy. PMID:11329712

  11. Relationships among Alcohol Outlet Density, Alcohol Use, and Intimate Partner Violence Victimization among Young Women in the United States

    ERIC Educational Resources Information Center

    Waller, Martha W.; Iritani, Bonita J.; Christ, Sharon L.; Clark, Heddy Kovach; Moracco, Kathryn E.; Halpern, Carolyn Tucker; Flewelling, Robert L.

    2012-01-01

    Greater access to alcohol has been widely found to be associated with many negative outcomes including violence perpetration. This study examines the relationship between alcohol outlet density, alcohol use, and intimate partner violence (IPV) victimization among young women in the United States. A direct association between alcohol outlet density…

  12. Antimicrobial peptides with potential for biofilm eradication: synthesis and structure activity relationship studies of battacin peptides.

    PubMed

    De Zoysa, Gayan Heruka; Cameron, Alan James; Hegde, Veena V; Raghothama, Srinivasarao; Sarojini, Vijayalekshmi

    2015-01-22

    We report on the first chemical syntheses and structure-activity analyses of the cyclic lipopeptide battacin which revealed that conjugation of a shorter fatty acid, 4-methyl-hexanoic acid, and linearization of the peptide sequence improves antibacterial activity and reduces hemolysis of mouse blood cells. This surprising finding of higher potency in linear lipopeptides than their cyclic counterparts is economically beneficial. This novel lipopeptide was membrane lytic and exhibited antibiofilm activity against Pseudomonas aeruginosa, Staphylococcus aureus, and, for the first time, Pseudomonas syringe pv. actinidiae. The peptide was unstructured in aqueous buffer and dimyristoylphosphatidylcholine-polymerized diacetylene vesicles, with 12% helicity induced in 50% v/v of trifluoroethanol. Our results indicate that a well-defined secondary structure is not essential for the observed antibacterial activity of this novel lipopeptide. A truncated pentapeptide conjugated to 4-methyl hexanoic acid, having similar potency against Gram negative and Gram positive pathogens was identified through alanine scanning. PMID:25495219

  13. Simulated Screens of DNA Encoded Libraries: The Potential Influence of Chemical Synthesis Fidelity on Interpretation of Structure-Activity Relationships.

    PubMed

    Satz, Alexander L

    2016-07-11

    Simulated screening of DNA encoded libraries indicates that the presence of truncated byproducts complicates the relationship between library member enrichment and equilibrium association constant (these truncates result from incomplete chemical reactions during library synthesis). Further, simulations indicate that some patterns observed in reported experimental data may result from the presence of truncated byproducts in the library mixture and not structure-activity relationships. Potential experimental methods of minimizing the presence of truncates are assessed via simulation; the relationship between enrichment and equilibrium association constant for libraries of differing purities is investigated. Data aggregation techniques are demonstrated that allow for more accurate analysis of screening results, in particular when the screened library contains significant quantities of truncates. PMID:27116029

  14. Quantitative structure-activity relationship modeling on in vitro endocrine effects and metabolic stability involving 26 selected brominated flame retardants.

    PubMed

    Harju, Mikael; Hamers, Timo; Kamstra, Jorke H; Sonneveld, Edwin; Boon, Jan P; Tysklind, Mats; Andersson, Patrik L

    2007-04-01

    In this work, quantitative structure-activity relationships (QSARs) were developed to aid human and environmental risk assessment processes for brominated flame retardants (BFRs). Brominated flame retardants, such as the high-production-volume chemicals polybrominated diphenyl ethers (PBDEs), tetrabromobisphenol A, and hexabromocyclododecane, have been identified as potential endocrine disruptors. Quantitative structure-activity relationship models were built based on the in vitro potencies of 26 selected BFRs. The in vitro assays included interactions with, for example, androgen, progesterone, estrogen, and dioxin (aryl hydrocarbon) receptor, plus competition with thyroxine for its plasma carrier protein (transthyretin), inhibition of estradiol sulfation via sulfotransferase, and finally, rate of metabolization. The QSAR modeling, a number of physicochemical parameters were calculated describing the electronic, lipophilic, and structural characteristics of the molecules. These include frontier molecular orbitals, molecular charges, polarities, log octanol/water partitioning coefficient, and two- and three-dimensional molecularproperties. Experimental properties were included and measured for PBDEs, such as their individual ultraviolet spectra (200-320 nm) and retention times on three different high-performance liquid chromatography columns and one nonpolar gas chromatography column. Quantitative structure-activity relationship models based on androgen antagonism and metabolic degradation rates generally gave similar results, suggesting that lower-brominated PBDEs with bromine substitutions in ortho positions and bromine-free meta- and para positions had the highest potencies and metabolic degradation rates. Predictions made for the constituents of the technical flame retardant Bromkal 70-5DE found BDE 17 to be a potent androgen antagonist and BDE 66, which is a relevant PBDE in environmental samples, to be only a weak antagonist. PMID:17447568

  15. Structure-activity relationship of triazafluorenone derivatives as potent and selective mGluR1 antagonists.

    PubMed

    Zheng, Guo Zhu; Bhatia, Pramila; Daanen, Jerome; Kolasa, Teodozyj; Patel, Meena; Latshaw, Steven; El Kouhen, Odile F; Chang, Renjie; Uchic, Marie E; Miller, Loan; Nakane, Masaki; Lehto, Sonya G; Honore, Marie P; Moreland, Robert B; Brioni, Jorge D; Stewart, Andrew O

    2005-11-17

    SAR (structure-activity relationship) studies of triazafluorenone derivatives as potent mGluR1 antagonists are described. The triazafluorenone derivatives are non-amino acid derivatives and noncompetitive mGluR1 antagonists that bind at a putative allosteric recognition site located within the seven-transmembrane domain of the receptor. These triazafluorenone derivatives are potent, selective, and systemically active mGluR1 antagonists. Compound 1n, for example, was a very potent mGluR1 antagonist (IC50 = 3 nM) and demonstrated full efficacy in various in vivo animal pain models. PMID:16279797

  16. Extended Functional Groups (EFG): An Efficient Set for Chemical Characterization and Structure-Activity Relationship Studies of Chemical Compounds.

    PubMed

    Salmina, Elena S; Haider, Norbert; Tetko, Igor V

    2015-01-01

    The article describes a classification system termed "extended functional groups" (EFG), which are an extension of a set previously used by the CheckMol software, that covers in addition heterocyclic compound classes and periodic table groups. The functional groups are defined as SMARTS patterns and are available as part of the ToxAlerts tool (http://ochem.eu/alerts) of the On-line CHEmical database and Modeling (OCHEM) environment platform. The article describes the motivation and the main ideas behind this extension and demonstrates that EFG can be efficiently used to develop and interpret structure-activity relationship models. PMID:26703557

  17. Discovery of potent CCR4 antagonists: Synthesis and structure-activity relationship study of 2,4-diaminoquinazolines.

    PubMed

    Yokoyama, Kazuhiro; Ishikawa, Noriko; Igarashi, Susumu; Kawano, Noriyuki; Hattori, Kazuyuki; Miyazaki, Takahiro; Ogino, Shin-ichi; Matsumoto, Yuzo; Takeuchi, Makoto; Ohta, Mitsuaki

    2008-07-15

    A new series of quinazolines that function as CCR4 antagonists were discovered during the screening of our corporate compound libraries. Subsequent compound optimization elucidated the structure-activity relationships and led the identification of 2-(1,4'-bipiperidine-1'-yl)-N-cycloheptyl-6,7-dimethoxyquinazolin-4-amine 14a, which showed potent inhibition in the [(35)S]GTPgammaS-binding assay (IC(50)=18nM). This compound also inhibited the chemotaxis of human and mouse CCR4-expressing cells (IC(50)=140nM, 39nM). PMID:18539035

  18. Chemical modification and structure-activity relationships of pyripyropenes. 3. Synthetic conversion of pyridine-pyrone moiety.

    PubMed

    Obata, R; Sunazuka, T; Tian, Z; Tomoda, H; Harigaya, Y; Omura, S

    1997-03-01

    Structure-activity relationships of the pyridine-pyrone moiety in pyripyropene A (1), a potent acyl-CoA: cholesterol acyltransferase (ACAT) inhibitor of fungal origin, were studied. Several kinds of aromatic or hetero ring substituents for the pyridine moiety were synthesized using unique degradation reaction, following by gamma-acylation. All the six synthesized analogs decreased the inhibitory activity with 20 to 200 times larger IC50 values than that of 1. Furthermore, the pyridine-pyrone substituent also dramatically decrease the inhibitory activity. Thus, the pyridine-pyrone moiety is important for eliciting potent ACAT inhibition. PMID:9127194

  19. Chemical modification and structure-activity relationships of pyripyropenes. 3. Synthetic conversion of pyridine-pyrone moiety

    PubMed

    Obata; Sunazuka; Tian; Tomoda; Harigaya; Omura

    1997-03-01

    Structure-activity relationships of the pyridine-pyrone moiety in pyripyropene A (1), a potent acyl-CoA : cholesterol acyltransferase (ACAT) inhibitor of fungal origin, were studied. Several kinds of aromatic or hetero ring substituents for the pyridine moiety were synthesized using unique degradation reaction, following by gamma-acylation. All the six synthesized analogs decreased the inhibitory activity with 20 to 200 times larger IC50 values than that of 1. Furthermore, the pyridine-pyrone substituent also dramatically decrease the inhibitory activity. Thus, the pyridine-pyrone moiety is important for eliciting potent ACAT inhibition. PMID:9439694

  20. Design, Synthesis and Structure-Activity Relationship Studies of Novel 4 (1-adamantyl) Phenyl Analogues as HIF-1α Inhibitors.

    PubMed

    Xia, Yan; Duan, Qiong; Zhao, Bao-Hua; Li, Dong-Feng; Hou, Rui-Bin

    2016-01-01

    Hypoxia inducible factor-1 (HIF-1) is a key mediator during cancer cells to adapt tumor hypoxic condition. In this study, a series of adamantane-based compounds were synthesized and evaluated as potential inhibitors of HIF-1α. Examination of their structure-activity relationship (SAR) identified the adamantane-containing indole derivative 20a as a potent inhibitor of HIF-1α in Hep3B cell lines under tumor hypoxia (IC50 = 0.02 µM). The study herein may provide valuable information for the development of novel therapeutics against cancer and tumor angiogenesis. PMID:26548744

  1. MOLECULAR INTERACTION POTENTIALS FOR THE DEVELOPMENT OF STRUCTURE-ACTIVITY RELATIONSHIPS

    EPA Science Inventory

    Abstract
    One reasonable approach to the analysis of the relationships between molecular structure and toxic activity is through the investigation of the forces and intermolecular interactions responsible for chemical toxicity. The interaction between the xenobiotic and the bio...

  2. Structure-activity relationship of lipid core peptide-based Group A Streptococcus vaccine candidates.

    PubMed

    Chan, Amy; Hussein, Waleed M; Ghaffar, Khairunnisa Abdul; Marasini, Nirmal; Mostafa, Ahmed; Eskandari, Sharareh; Batzloff, Michael R; Good, Michael F; Skwarczynski, Mariusz; Toth, Istvan

    2016-07-15

    Infection with Group A Streptococcus (GAS) can result in a range of different illnesses, some of which are fatal. Currently, our efforts to develop a vaccine against GAS focuses on the lipid core peptide (LCP) system, a subunit vaccine containing a lipoamino acid (LAA) moiety which allows the stimulation of systemic antibody activity. In the present study, a peptide (J14) representing the B-cell epitope from the GAS M protein was incorporated alongside a universal T-helper epitope (P25) in four LCP constructs of different spatial orientation or LAA lengths. Through structure-activity studies, it was discovered that while the alteration of the LCP orientation had a weaker effect on immunostimulation, increasing the LAA side chain length within the construct increased antibody responses in murine models. Furthermore, the mice immunised with the lead LCP construct were also able to maintain antibody activity throughout the course of five months. These findings highlight the importance of LAA moieties in the development of intranasal peptide vaccines and confirmed that its side chain length has an effect on the immunogenicity of the structure. PMID:27246859

  3. Probing the structure-activity relationship of endogenous histone deacetylase complexes with immobilized peptide-inhibitors.

    PubMed

    Sindlinger, Julia; Bierlmeier, Jan; Geiger, Lydia-Christina; Kramer, Katharina; Finkemeier, Iris; Schwarzer, Dirk

    2016-05-01

    Histone deacetylases (HDACs) are key regulators of numerous cellular proteins by removing acetylation marks from modified lysine residues. Peptide-based HDAC probes containing α-aminosuberic acid ω-hydroxamate have been established as useful tools for investigating substrate selectivity and composition of endogenous HDAC complexes in cellular lysates. Here we report a structure-activity study of potential HDAC-probes containing derivatives of the hydroxamate moieties. While most of these probes did not recruit significant amounts of endogenous HDACs from cellular lysates, peptides containing Nε-acetyl-Nε-hydroxy-L-lysine served as HDAC probe. The recruitment efficiency varied between HDACs and was generally lower than that of α-aminosuberic acid ω-hydroxamate probes, but showed a similar global interaction profile. These findings indicate that Nε-acetyl-Nε-hydroxy-L-lysine might be a useful tool for investigations on HDAC complexes and the development of HDAC inhibitors. Copyright © 2016 European Peptide Society and John Wiley & Sons, Ltd. PMID:27071932

  4. The structure-activity relationships of the antiviral chemotherapeutic activity of isatin β-thiosemicarbazone

    PubMed Central

    Bauer, D. J.; Sadler, P. W.

    1960-01-01

    As part of an investigation devoted to the development of new antiviral agents a compound of established antiviral activity has been subjected to systematic structural modification. The structure-activity data so obtained have been used in the design of new compounds, some of which are described. The compound chosen was isatin β-thiosemicarbazone, which has high activity against neurovaccinia infection in mice, and a 4-point parallel-line assay of in vivo chemotherapeutic activity has been developed, which has enabled the activity of the derivatives to be determined against isatin β-thiosemicarbazone as a standard. The overall dimensions of the isatin β-thiosemicarbazone molecule appear to be nearly maximal for the retention of high activity, as all substituents in the aromatic ring decrease the activity irrespective of their nature or position. The projection of the -CS.NH2 group in relation to the ring nitrogen was found to be critical, as the α-thiosemicarbazone was inactive. A number of modifications of the side-chain were investigated:all led to reduction or loss of antiviral activity. The antiviral activity showed a positive correlation with chloroform solubility over a considerable range. The most active compound encountered was 1-ethylisatin β-thiosemicarbazone, with an activity of 286 (isatin β-thiosemicarbazone≡100). Isatin β-thiosemicarbazone showed no activity against 15 other viruses, and 20 related compounds showed on activity against ectromelia. PMID:13797622

  5. COMPUTER-ASSISTED STRUCTURE ACTIVITY RELATIONSHIPS OF NITROGENOUS CYCLIC COMPOUNDS TESTED IN SALMONELLA ASSAYS FOR MUTAGENICITY

    EPA Science Inventory

    Study of the relationship between mutagenicity and molecular structure for a data set of nitrogenous cyclic compounds is reported. A computerized SAR system (ADAPT) was utilized to classify a data set of 114 nitrogenous cyclic compounds with 19 molecular descriptors. All of the d...

  6. Structural interpretation of activity cliffs revealed by systematic analysis of structure-activity relationships in analog series.

    PubMed

    Sisay, Mihiret T; Peltason, Lisa; Bajorath, Jürgen

    2009-10-01

    Discontinuity in structure-activity relationships (SARs) is caused by so-called activity cliffs and represents one of the major caveats in SAR modeling and lead optimization. At activity cliffs, small structural modifications of compounds lead to substantial differences in potency that are essentially unpredictable using quantitative structure-activity relationship (QSAR) methods. In order to better understand SAR discontinuity at the molecular level of detail, we have analyzed different compound series in combinatorial analog graphs and determined substitution patterns that introduce activity cliffs of varying magnitude. So identified SAR determinants were then analyzed on the basis of complex crystal structures to enable a structural interpretation of SAR discontinuity and underlying activity cliffs. In some instances, SAR discontinuity detected within analog series could be well rationalized on the basis of structural data, whereas in others a structural explanation was not possible. This reflects the intrinsic complexity of small molecule SARs and suggests that the analysis of short-range receptor-ligand interactions seen in X-ray structures is insufficient to comprehensively account for SAR discontinuity. However, in other cases, SAR information extracted from ligands was incomplete but could be deduced taking X-ray data into account. Thus, taken together, these findings illustrate the complementarity of ligand-based SAR analysis and structural information. PMID:19761254

  7. Design and analysis of structure-activity relationship of novel antimicrobial peptides derived from the conserved sequence of cecropin.

    PubMed

    Hao, Gang; Shi, Yong-Hui; Han, Jing-Hui; Li, Qi-Hui; Tang, Ya-Li; Le, Guo-Wei

    2008-03-01

    We have de novo designed four antimicrobial peptides AMP-A/B/C/D, the 51-residues peptides, which are based on the conserved sequence of cecropin. In the present study, the four peptides were chemically synthesized and their activities assayed. Their secondary structure, amphipathic property, electric field distribution and transmembrane domain were subsequently predicted by bioinformatics tools. Finally, the structure-activity relationship was analyzed from the results of activity experiments and prediction. The results of activity experiments indicated that AMP-B/C/D clearly possessed excellent broad-spectrum activity against bacteria, whereas AMP-A was almost inactive against most of the bacterial strains tested. AMP-B/C/D showed more potent activity against Gram-positive bacteria than against Gram-negative bacteria. By utilizing bioinformatics analysis tools, we found that the secondary structure of the four cation peptides was mainly alpha-helix, and the result of CD spectrum also displayed that all the peptides had considerable alpha-helix in the presence of either 50% TFE or SDS micelles. AMP-C showed much better activity than other peptides against most of the bacteria tested, owing to its remarkable cation property and the amphipathic character of its N-terminal. The study of structure-activity relationship of the designed peptides confirmed that amphipathic structure and high net positive charge were prerequisites for maintaining their activities. PMID:17929330

  8. Folate-vinca alkaloid conjugates for cancer therapy: a structure-activity relationship.

    PubMed

    Leamon, Christopher P; Vlahov, Iontcho R; Reddy, Joseph A; Vetzel, Marilynn; Santhapuram, Hari Krishna R; You, Fei; Bloomfield, Alicia; Dorton, Ryan; Nelson, Melissa; Kleindl, Paul; Vaughn, Jeremy F; Westrick, Elaine

    2014-03-19

    Vintafolide is a potent folate-targeted vinca alkaloid small molecule drug conjugate (SMDC) that has shown promising results in multiple clinical oncology studies. Structurally, vintafolide consists of 4 essential modules: (1) folic acid, (2) a hydrophilic peptide spacer, (3) a disulfide-containing, self-immolative linker, and (4) the cytotoxic drug, desacetylvinblastine hydrazide (DAVLBH). Here, we report a structure-activity study evaluating the biological impact of (i) substituting DAVLBH within the vintafolide molecule with other vinca alkaloid analogues such as vincristine, vindesine, vinflunine, or vinorelbine; (ii) substituting the naturally (S)-configured Asp-Arg-Asp-Asp-Cys peptide with alternative hydrophilic spacers of varied composition; and (iii) varying the composition of the linker module. A series of vinca alkaloid-containing SMDCs were synthesized and purified by HPLC and LCMS. The SMDCs were screened in vitro against folate receptor (FR)-positive cells, and anti-tumor activity was tested against well-established subcutaneous FR-positive tumor xenografts. The cytotoxic and anti-tumor activity was directly compared to that produced by vintafolide. Among all the folate vinca alkaloid SMDCs tested, DAVLBH-containing SMDCs were active, while those constructed with vincristine, vindesine, or vinorelbine analogues failed to produce meaningful biological activity. Within the DAVLBH series, having a bioreleasable, self-immolative linker system was found to be critical for activity since multiple analogues constructed with thioether-based linkers all failed to produce meaningful activity both in vitro and in vivo. Substitutions of some or all of the natural amino acids within vintafolide's hydrophilic spacer module did not significantly change the in vitro or in vivo potency of the SMDCs. Vintafolide remains one of the most potent folate-vinca alkaloid SMDCs produced to date, and continued clinical development is warranted. PMID:24564229

  9. Reconsidering the Relationship between Alcohol and Lethal Violence

    ERIC Educational Resources Information Center

    Phillips, Scott; Matusko, Jacqueline; Tomasovic, Elizabeth

    2007-01-01

    Prior event-based research regarding the relationship between alcohol and violence suffers from important limitations, including the absence of a comparison group, an inappropriate comparison group, or a comparison group that could be considered appropriate but does not control for potential confounders. To overcome such limitations, we use a…

  10. Problems involved in the specification and interpretation of quantitative structure-activity relationships. Part 1: A modified type of structure-activity equations.

    PubMed

    Mager, H; Barth, A

    1979-01-01

    It has been demonstrated that ordinary regression coefficients of a quantitative structure-activity equation depend strongly on the scaling both of the biological parameter and the explanatory variables (regressors). Even in the case of only two regressors this fact may lead to challengable interpretations regarding the relative performances of the explanatory variables, say physicochemical parameters. The use of standardized variables and, consequently, of standardized regression coefficients is proposed in order to get a better insight into the mechanistic features of the mode of action of the congeneric series under investigation. The procedure has been illustrated with examples adapted from the literature. PMID:396534

  11. Toll-like receptor 4-related immunostimulatory polysaccharides: Primary structure, activity relationships, and possible interaction models.

    PubMed

    Zhang, Xiaorui; Qi, Chunhui; Guo, Yan; Zhou, Wenxia; Zhang, Yongxiang

    2016-09-20

    Toll-like receptor (TLR) 4 is an important polysaccharide receptor; however, the relationships between the structures and biological activities of TLR4 and polysaccharides remain unknown. Many recent findings have revealed the primary structure of TLR4/MD-2-related polysaccharides, and several three-dimensional structure models of polysaccharide-binding proteins have been reported; and these models provide insights into the mechanisms through which polysaccharides interact with TLR4. In this review, we first discuss the origins of polysaccharides related to TLR4, including polysaccharides from higher plants, fungi, bacteria, algae, and animals. We then briefly describe the glucosidic bond types of TLR4-related heteroglycans and homoglycans and describe the typical molecular weights of TLR4-related polysaccharides. The primary structures and activity relationships of polysaccharides with TLR4/MD-2 are also discussed. Finally, based on the existing interaction models of LPS with TLR4/MD-2 and linear polysaccharides with proteins, we provide insights into the possible interaction models of polysaccharide ligands with TLR4/MD-2. To our knowledge, this review is the first to summarize the primary structures and activity relationships of TLR4-related polysaccharides and the possible mechanisms of interaction for TLR4 and TLR4-related polysaccharides. PMID:27261743

  12. Relationship Between the Thyroid Axis and Alcohol Craving

    PubMed Central

    Aoun, Elie G.; Lee, Mary R.; Haass-Koffler, Carolina L.; Swift, Robert M.; Addolorato, Giovanni; Kenna, George A.; Leggio, Lorenzo

    2015-01-01

    Aims: A few studies have suggested a relationship between thyroid hormones and alcohol dependence (AD) such as a blunted increase of thyroid stimulating hormone (TSH) in response to thyrotropin-releasing hormone (TRH), lower levels of circulating free triiodothyronine (fT3) and free thyroxine (fT4) levels and down regulation of the TRH receptors. The current study aimed to explore the relationship between the hormones of the thyroid axis and alcohol-seeking behaviors in a sample of alcohol-dependent patients. Methods: Forty-two treatment-seeking alcohol-dependent individuals enrolled in a 12-week treatment study were considered. The Timeline Follow Back (TLFB) was used to assess the number of drinks consumed during the 12-week period. Blood levels of thyroid hormones (TSH, fT3 and fT4) were measured prior to and at the end of treatment. Questionnaires were administered to evaluate craving for alcohol [Penn Alcohol Craving Scale (PACS) and the Obsessive Compulsive Drinking Scale (OCDS) and its two subscales ODS for obsessions and CDS for compulsions] as well as anxiety [State and Trait Inventory (STAI)], depression [the Zung Self-Rating Depression Scale (Zung)] and aggression [the Aggressive Questionnaire (AQ)]. Results: At baseline, we found significant positive correlations between fT3 and OCDS (r = 0.358, P = 0.029) and CDS (r = 0.405, P = 0.013) and negative correlations between TSH levels and STAI (r = −0.342, P = 0.031), and AQ (r = −0.35, P = 0.027). At the end of the 12-week study period, abstinent patients had a greater change in TSH than those who relapsed (−0.4 vs. −0.25, F(1,24) = 5.4, P = 0.029). Conclusion: If confirmed in larger samples, these findings could suggest that the thyroid axis might represent a biomarker of alcohol craving and drinking. PMID:25433251

  13. Quantitative structure-activity relationships for skin sensitization potential of urushiol analogues.

    PubMed

    Roberts, D W; Benezra, C

    1993-08-01

    The relative alkylation index (RAI), a theoretically derived parameter intended to quantify the relative extent of carrier haptenation resulting from a given dose of a given sensitizer, has previously been successfully applied to the analysis of relative sensitization potential and dose-response data for a variety of contact allergens which are directly electrophilic. Here the RAI concept is applied to analysis of data on compounds related to urushiol (i.e., 3-substituted catechols), the naturally occurring mixture of allergens responsible for contact allergy to poison ivy and poison oak. These allergens are believed to act as pro-electrophiles, being oxidized to electrophilic orthoquinones in vivo. It is found that the various types of urushiol derivatives fit the same sort of RAI-sensitization relationships as expected theoretically and as found previously with direct acting electrophiles. There is evidence that in many cases, the test conditions were such that overload effects, whereby the degree of sensitization induced decreases with increasing carrier haptenation, applied. It is also concluded that the question as to the relative sensitization potencies of the naturally occurring urushiols remains open. The commonly held view that with these materials, sensitization potential increases with increasing unsaturation in the 3-hydrocarbyl chain of the 3-hydrocarbyl catechols, is based on evidence that is capable of alternative interpretation. PMID:8365181

  14. Neuroprotective and Antioxidant Activities of 4-Methylcoumarins: Development of Structure-Activity Relationships.

    PubMed

    Malhotra, Shashwat; Tavakkoli, Marjan; Edraki, Najmeh; Miri, Ramin; Sharma, Sunil Kumar; Prasad, Ashok Kumar; Saso, Luciano; Len, Christophe; Parmar, Virinder Singh; Firuzi, Omidreza

    2016-01-01

    Coumarins are a major class of polyphenols that are abundantly present in many dietary plants and possess different biological activities. Neuroprotective effect of 28 variously substituted 4-methylcoumarins was evaluated in a cell model of oxidative stress-induced neurodegeneration, which measures viability in PC12 cells challenged with hydrogen peroxide by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The inhibitory activity of these compounds against intracellular reactive oxygen species (ROS) formation was also determined by 2',7'-dichlorofluorescein diacetate method in the same cells. Chemical redox-based assays including 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP) tests were employed to explore structure-antioxidant activity relationships in a cell-free environment. The results demonstrated that 4-methylcoumarins containing ortho-dihydroxy or ortho-diacetoxy substituents on the benzenoid ring possess considerable neuroprotective effects. ortho-Dihydroxy compounds inhibited cytotoxicity (44.7-62.9%) and ROS formation (41.6-71.1%) at 50 µM and showed considerable antioxidant effects. We conclude that 4-methylcoumarins are promising neuroprotective and antioxidant scaffolds potentially usefull for management of neurodegenerative diseases. PMID:27582333

  15. Design, structure activity relationship, cytotoxicity and evaluation of antioxidant activity of curcumin derivatives/analogues.

    PubMed

    Sahu, Pramod K

    2016-10-01

    New fourteen 3,4-dihydropyrimidine derivatives/analogues of curcumin (2a-2n) were designed, synthesized and biologically evaluated for their cytotoxicity and antioxidant activity. Cytotoxicity effect has been evaluated against three cell lines HeLa, HCT-116 and QG-56 by MTT assay method. From SAR study, it has been revealed that particularly, compound 2e and 2j (IC50 value 12.5 μM) have shown better cytotoxicity effect against three cell lines. According to results of SAR study, it was found that 3,4-dihydropyrimidines of curcumin, 2c, 2d, 2j and 2n exhibited better antioxidant activity than curcumin. A correlation of structure and activities relationship of these compounds with respect to drug score profiles and other physico-chemical properties of drugs are described and verified experimentally. Therefore, we conclude that physico-chemical analyses may prove structural features of curcumin analogues with their promising combined cytotoxicity/antioxidant activity and it is also concluded from virtual and practical screening that the compounds were varied to possess a broad range of lipophilic character, revealed by Log P values. PMID:27318975

  16. Investigation of the Structure-Activity Relationships of Aza-A-Ring Indenoisoquinoline Topoisomerase I Poisons.

    PubMed

    Beck, Daniel E; Reddy, P V Narasimha; Lv, Wei; Abdelmalak, Monica; Tender, Gabrielle S; Lopez, Sophia; Agama, Keli; Marchand, Christophe; Pommier, Yves; Cushman, Mark

    2016-04-28

    Several indenoisoquinolines have shown promise as anticancer agents in clinical trials. Incorporation of a nitrogen atom into the indenoisoquinoline scaffold offers the possibility of favorably modulating ligand-binding site interactions, physicochemical properties, and biological activities. Four series of aza-A-ring indenoisoquinolines were synthesized in which the nitrogen atom was systematically rotated through positions 1, 2, 3, and 4. The resulting compounds were tested to establish the optimal nitrogen position for topoisomerase IB (Top1) enzyme poisoning activity and cytotoxicity to human cancer cells. The 4-aza compounds were the most likely to yield derivatives with high Top1 inhibitory activity. However, the relationship between structure and cytotoxicity was more complicated since the potency was influenced strongly by the side chains on the lactam nitrogen. The most cytotoxic azaindenoisoquinolines 45 and 46 had nitrogen in the 2- or 3-positions and a 3'-dimethylaminopropyl side chain, and they had MGM GI50 values that were slightly better than the corresponding indenoisoquinoline 64. PMID:27070999

  17. Angiotensin-converting enzyme inhibitory effects by plant phenolic compounds: a study of structure activity relationships.

    PubMed

    Al Shukor, Nadin; Van Camp, John; Gonzales, Gerard Bryan; Staljanssens, Dorien; Struijs, Karin; Zotti, Moises J; Raes, Katleen; Smagghe, Guy

    2013-12-01

    In this study, 22 phenolic compounds were investigated to inhibit the angiotensin-converting enzyme (ACE). Tannic acid showed the highest activity (IC50 = 230 μM). The IC50 values obtained for phenolic acids and flavonoids ranged between 0.41 and 9.3 mM. QSAR analysis confirmed that the numbers of hydroxyl groups on the benzene ring play an important role for activity of phenolic compounds and that substitution of hydroxyl groups by methoxy groups decreased activity. Docking studies indicated that phenolic acids and flavonoids inhibit ACE via interaction with the zinc ion and this interaction is stabilized by other interactions with amino acids in the active site. Other compounds, such as resveratrol and pyrogallol, may inhibit ACE via interactions with amino acids at the active site, thereby blocking the catalytic activity of ACE. These structure-function relationships are useful for designing new ACE inhibitors and potential blood-pressure-lowering compounds based on phenolic compounds. PMID:24219111

  18. Flavonoids as CDK1 Inhibitors: Insights in Their Binding Orientations and Structure-Activity Relationship

    PubMed Central

    Navarro-Retamal, Carlos

    2016-01-01

    In the last years, the interactions of flavonoids with protein kinases (PKs) have been described by using crystallographic experiments. Interestingly, different orientations have been found for one flavonoid inside different PKs and different chemical substitutions lead to different orientations of the flavonoid scaffold inside one PK. Accordingly, orientation predictions of novel analogues could help to the design of flavonoids with high PK inhibitory activities. With this in mind, we studied the binding modes of 37 flavonoids (flavones and chalcones) inside the cyclin-dependent PK CDK1 using docking experiments. We found that the compounds under study adopted two different orientations into the active site of CDK1 (orientations I and II in the manuscript). In addition, quantitative structure–activity relationship (QSAR) models using CoMFA and CoMSIA methodologies were constructed to explain the trend of the CDK1 inhibitory activities for the studied flavonoids. Template-based and docking-based alignments were used. Models developed starting from docking-based alignment were applied for describing the whole dataset and compounds with orientation I. Adequate R2 and Q2 values were obtained by each method; interestingly, only hydrophobic and hydrogen bond donor fields describe the differential potency of the flavonoids as CDK1 inhibitors for both defined alignments and subsets. Our current application of docking and QSAR together reveals important elements to be drawn for the design of novel flavonoids with increased PK inhibitory activities. PMID:27517610

  19. New imidazoquinoxaline derivatives: Synthesis, biological evaluation on melanoma, effect on tubulin polymerization and structure-activity relationships.

    PubMed

    Zghaib, Zahraa; Guichou, Jean-François; Vappiani, Johanna; Bec, Nicole; Hadj-Kaddour, Kamel; Vincent, Laure-Anaïs; Paniagua-Gayraud, Stéphanie; Larroque, Christian; Moarbess, Georges; Cuq, Pierre; Kassab, Issam; Deleuze-Masquéfa, Carine; Diab-Assaf, Mona; Bonnet, Pierre-Antoine

    2016-06-01

    Microtubules are considered as important targets of anticancer therapy. EAPB0503 and its structural imidazo[1,2-a]quinoxaline derivatives are major microtubule-interfering agents with potent anticancer activity. In this study, the synthesis of several new derivatives of EAPB0503 is described, and the anticancer efficacy of 13 novel derivatives on A375 human melanoma cell line is reported. All new compounds show significant antiproliferative activity with IC50 in the range of 0.077-122μM against human melanoma cell line (A375). Direct inhibition of tubulin polymerization assay in vitro is also assessed. Results show that compounds 6b, 6e, 6g, and EAPB0503 highly inhibit tubulin polymerization with percentages of inhibition of 99%, 98%, 90%, and 84% respectively. Structure-activity relationship studies within the series are also discussed in line with molecular docking studies into the colchicine-binding site of tubulin. PMID:27094151

  20. Synthesis and structure-activity relationship of α-keto amides as enterovirus 71 3C protease inhibitors.

    PubMed

    Zeng, Debin; Ma, Yuying; Zhang, Rui; Nie, Quandeng; Cui, Zhengjie; Wang, Yaxin; Shang, Luqing; Yin, Zheng

    2016-04-01

    α-Keto amide derivatives as enterovirus 71 (EV71) 3C protease (3C(pro)) inhibitors have been synthesized and assayed for their biochemical and antiviral activities. structure-activity relationship (SAR) study indicated that small moieties were primarily tolerated at P1' and the introduction of para-fluoro benzyl at P2 notably improved the potency of inhibitor. Inhibitors 8v, 8w and 8x exhibited satisfactory activity (IC50=1.32±0.26μM, 1.88±0.35μM and 1.52±0.31μM, respectively) and favorable CC50 values (CC50>100μM). α-Keto amide may represent a good choice as a warhead for EV71 3C(pro) inhibitor. PMID:26916437

  1. Structure-activity relationships for novel drug precursor N-substituted-6-acylbenzothiazolon derivatives: A theoretical approach

    NASA Astrophysics Data System (ADS)

    Sıdır, Yadigar Gülseven; Sıdır, İsa

    2013-08-01

    In this study, the twelve new modeled N-substituted-6-acylbenzothiazolon derivatives having analgesic analog structure have been investigated by quantum chemical methods using a lot of electronic parameters and structure-activity properties; such as molecular polarizability (α), dipole moment (μ), EHOMO, ELUMO, q-, qH+, molecular volume (Vm), ionization potential (IP), electron affinity (EA), electronegativity (χ), molecular hardness (η), molecular softness (S), electrophilic index (ω), heat of formation (HOF), molar refractivity (MR), octanol-water partition coefficient (log P), thermochemical properties (entropy (S), capacity of heat (Cv)); as to investigate activity relationships with molecular structure. The correlations of log P with Vm, MR, ω, EA, EHOMO - ELUMO (ΔE), HOF in aqueous phase, χ, μ, S, η parameters, respectively are obtained, while the linear relation of log P with IP, Cv, HOF in gas phase are not observed. The log P parameter is obtained to be depending on different properties of compounds due to their complexity.

  2. New imidazo[1,2-b]pyrazoles as anticancer agents: synthesis, biological evaluation and structure activity relationship analysis.

    PubMed

    Grosse, Sandrine; Mathieu, Véronique; Pillard, Christelle; Massip, Stéphane; Marchivie, Mathieu; Jarry, Christian; Bernard, Philippe; Kiss, Robert; Guillaumet, Gérald

    2014-09-12

    Synthesis and functionalization strategies of the imidazo[1,2-b]pyrazole core were developed giving a rapid access to three series of novel imidazo[1,2-b]pyrazole type derivatives: C-2/C-6/C-7 trisubstituted, C-2/C-3/C-6 tri(hetero)arylated and C-2/C-3/C-6/C-7 tetrasubstituted imidazo[1,2-b]pyrazoles. 39 of the synthetized products were evaluated for in vitro anticancer activity using the MTT colorimetric assay against 5 human and 1 murine cancer cell lines. Promising in vitro growth inhibitory activities were exhibited by some of the target compounds. Of the 39 evaluated products, 4 displayed an IC50 ≤ 10 μM in the 6 cell lines analyzed (compounds 4d, 4g, 9a, 11a). A structure activity relationship analysis is also reported in this paper. PMID:25064349

  3. Cationic Membrane Peptides: Atomic-Level Insight of Structure-Activity Relationships from Solid-State NMR

    PubMed Central

    Su, Yongchao; Li, Shenhui; Hong, Mei

    2012-01-01

    Many membrane-active peptides, such as cationic cell-penetrating peptides (CPPs) and antimicrobial peptides (AMPs), conduct their biological functions by interacting with the cell membrane. The interactions of charged residues with lipids and water facilitate membrane insertion, translocation or disruption of these highly hydrophobic species. In this mini-review we will summarize high-resolution structural and dynamic findings towards the understanding of the structure-activity relationship of lipid membrane-bound CPPs and AMPs, as examples of the current development of solid-state NMR (SSNMR) techniques for studying membrane peptides. We will present the most recent atomic-resolution structure of the guanidinium-phosphate complex, as constrained from experimentally measured site-specific distances. These SSNMR results will be valuable specifically for understanding the intracellular translocation pathway of CPPs and antimicrobial mechanism of AMPs, and more generally broaden our insight into how cationic macromolecules interact with and cross the lipid membrane. PMID:23108593

  4. Synthesis and structure activity relationship study of N-substituted 3,5-diarylidenepiperidin- 4-ones as potential antitumor agents.

    PubMed

    El-Nassan, Hala Bakr

    2014-02-01

    A new series of N-substituted diarylidenepiperidin-4-ones was synthesized and screened for their possible anticancer activity at the NCI Developmental Therapeutic Program. Almost all the synthesized compounds showed more potent antiproliferative activity than curcumin. The most active compound in this study was 3,5-bis(4-bromobenzylidene)-1-propanoylpiperidin-4-one (8a) with MG-MID GI50, TGI, and LC50 values of 0.35, 1.62 and 9.12 µM, respectively. Compound 8a displayed broad spectrum antiproliferative activity with GI50 values below 1 µM in 81% of the tested cell lines and was found to be two folds more potent than EF-24. A detailed study of the structure activity relationship of the N-substitution was also described. PMID:24102314

  5. Mechanism of mitochondrial uncouplers, inhibitors, and toxins: focus on electron transfer, free radicals, and structure-activity relationships.

    PubMed

    Kovacic, Peter; Pozos, Robert S; Somanathan, Ratnasamy; Shangari, Nandita; O'Brien, Peter J

    2005-01-01

    The biology of the mitochondrial electron transport chain is summarized. Our approach to the mechanism of uncouplers, inhibitors, and toxins is based on electron transfer (ET) and reactive oxygen species (ROS). Extensive supporting evidence, which is broadly applicable, is cited. ROS can be generated either endogenously or exogenously. Generally, the reactive entities arise via redox cycling by ET functionalities, such as, quinones (or precursors), metal compounds, imines (or iminiums), and aromatic nitro compounds (or reduced metabolites). In most cases, the ET functions are formed metabolically. The toxic substances belong to many categories, e.g., medicinals, industrial chemicals, abused drugs, and pesticides. Structure-activity relationships are presented from the ET-ROS perspective, and also quantitatively. Evidence for the theoretical framework is provided by the protective effect of antioxidants. Among other topics addressed are proton flux, membrane pores, and apoptosis. There is support for the thesis that mitochondrial insult may contribute to illnesses and aging. PMID:16248817

  6. Calophyllum inophyllum and Calophyllum soulattri source of anti-proliferative xanthones and their structure-activity relationships.

    PubMed

    Mah, Siau Hui; Ee, Gwendoline Cheng Lian; Teh, Soek Sin; Sukari, Mohd Aspollah

    2015-01-01

    Extensive chromatographic isolation and purification of the extracts of the stem bark of Calophyllum inophyllum and Calophyllum soulattri have resulted in 11 xanthones. C. inophyllum gave inophinnin (1), inophinone (2), pyranojacareubin (5), rheediaxanthone A (6), macluraxanthone (7) and 4-hydroxyxanthone (8), while C. soulattri afforded soulattrin (3), phylattrin (4), caloxanthone C (9), brasixanthone B (10) and trapezifolixanthone (11). The structures of these compounds were determined on the basis of spectroscopic analyses such as 1D and 2D NMR, GC-MS, IR and UV. Cytotoxicity screening (MTT assay) carried out in vitro on all the xanthones using five human cancer cell lines indicated good activities for some of these xanthones. The structure-activity relationship study revealed that the inhibitory activities exhibited by these xanthone derivatives to be closely related to the existence and nature of the pyrano and the prenyl substituent groups on their skeleton. PMID:25229947

  7. Phomentrioloxin, a fungal phytotoxin with potential herbicidal activity, and its derivatives: a structure-activity relationship study.

    PubMed

    Cimmino, Alessio; Andolfi, Anna; Zonno, Maria Chiara; Boari, Angela; Troise, Ciro; Motta, Andrea; Vurro, Maurizio; Ash, Gavin; Evidente, Antonio

    2013-10-01

    Phomentrioloxin is a phytotoxic geranylcyclohexenetriol produced in liquid culture by Phomopsis sp. (teleomorph: Diaporthe gulyae), a potential mycoherbicide proposed for the control of the annual weed Carthamus lanatus. In this study, seven derivatives obtained by chemical modifications of the toxin were assayed for phytotoxic, antimicrobial, and zootoxic activities, and the structure-activity relationships were examined. Each compound was tested on nonhost weedy and agrarian plants, fungi, Gram+ and Gram- bacteria, and on brine shrimp larvae. The results provide insights into an investigation of the structural requirements for activity. The hydroxy groups at C-2 and C-4 appeared to be important features for the phytotoxicity, as well as an unchanged cyclohexentriol ring. A role seemed also to be played by the unsaturations of the geranyl side chain. These findings could be useful for understanding the mechanisms of action of new natural products, for identifying the active sites, and possibly in devising new herbicides of natural origin. PMID:24083323

  8. Small molecule non-peptide inhibitors of botulinum neurotoxin serotype E: Structure-activity relationship and a pharmacophore model.

    PubMed

    Kumar, Gyanendra; Agarwal, Rakhi; Swaminathan, Subramanyam

    2016-09-15

    Botulinum neurotoxins (BoNTs) are the most poisonous biological substance known to humans. They cause flaccid paralysis by blocking the release of acetylcholine at the neuromuscular junction. Here, we report a number of small molecule non-peptide inhibitors of BoNT serotype E. The structure-activity relationship and a pharmacophore model are presented. Although non-peptidic in nature, these inhibitors mimic key features of the uncleavable substrate peptide Arg-Ile-Met-Glu (RIME) of the SNAP-25 protein. Among the compounds tested, most of the potent inhibitors bear a zinc-chelating moiety connected to a hydrophobic and aromatic moiety through a carboxyl or amide linker. All of them show low micromolar IC50 values. PMID:27353886

  9. Enzymatic Methylation and Structure-Activity-Relationship Studies on Polycarcin V, a Gilvocarcin-Type Antitumor Agent

    PubMed Central

    Chen, Jhong-Min; Shepherd, Micah D.; Horn, Jamie; Leggas, Markos; Rohr, Jürgen

    2014-01-01

    Polycarcin V, a polyketide natural product of Streptomyces polyformus, was chosen to study structure-activity-relationships of the gilvocarcin group of antitumor antibiotics, because of a similar chemical structure and comparable bioactivity with gilvocarcin V, the principle compound of this group, and the feasibility of enzymatic modifications of its sugar moiety by auxiliary O-methyltransferases. Such enzymes were used to modify the interaction of the drug with histone H3, the biological target that interacts with the sugar moiety. Cytotoxicity assays revealed that a free 2’-OH group of the sugar moiety is essential to maintain the bioactivity of polycarcin V, apparently an important H-bond donor for the interaction with histone H3, while converting 3'-OH into an OCH3 group improved the bioactivity. Bis-methylated polycarcin derivatives revealed weaker activity than the parent compound, indicating that at least two H-bond donors in the sugar are necessary for optimal binding. PMID:25366963

  10. Studying the explanatory capacity of artificial neural networks for understanding environmental chemical quantitative structure-activity relationship models.

    PubMed

    Yang, Lei; Wang, Peng; Jiang, Yilin; Chen, Jian

    2005-01-01

    Although artificial neural networks (ANNs) have been shown to exhibit superior predictive power in the study of quantitative structure-activity relationships (QSARs), they have also been labeled a "black box" because they provide little explanatory insight into the relative influence of the independent variables in the predictive process so that little information on how and why compounds work can be obtained. Here, we have turned our interests to their explanatory capacities; therefore, a method was proposed for assessing the relative importance of variables indicating molecular structure, on the basis of axon connection weights and partial derivatives of the ANN output with respect to its input, which can identify variables that significantly contribute to network predictions, and providing a variable selection method for ANNs. We show that, by extending this approach to ANNs, the "black box" mechanics of ANNs can be greatly illuminated, thereby making it very useful in understanding environmental chemical QSAR models. PMID:16309287

  11. Semisynthesis and quantitative structure-activity relationship (QSAR) study of some cholesterol-based hydrazone derivatives as insecticidal agents.

    PubMed

    Yang, Chun; Shao, Yonghua; Zhi, Xiaoyan; Huan, Qu; Yu, Xiang; Yao, Xiaojun; Xu, Hui

    2013-09-01

    In continuation of our program aimed at the discovery and development of natural-product-based insecticidal agents, four series of novel cholesterol-based hydrazone derivatives were synthesized, and their insecticidal activity was tested against the pre-third-instar larvae of oriental armyworm, Mythimna separata (Walker) in vivo at 1mg/mL. All the derivatives showed the better insecticidal activity than their precursor cholesterol. Quantitative structure-activity relationship (QSAR) model demonstrated that six descriptors such as RDF085v, Mor06u, Mor11u, Dv, HATS0v and H-046, are likely to influence the insecticidal activity of these compounds. Among them, two important ones are the Mor06u and RDF085v. PMID:23891182

  12. Estimating the persistence of organic contaminants in indirect potable reuse systems using quantitative structure activity relationship (QSAR).

    PubMed

    Lim, Seung Joo; Fox, Peter

    2012-09-01

    Predictions from the quantitative structure activity relationship (QSAR) model EPI Suite were modified to estimate the persistence of organic contaminants in indirect potable reuse systems. The modified prediction included the effects of sorption, biodegradation, and oxidation that may occur during sub-surface transport. A retardation factor was used to simulate the mobility of adsorbed compounds during sub-surface transport to a recovery well. A set of compounds with measured persistent properties during sub-surface transport was used to validate the results of the modifications to the predictions of EPI Suite. A comparison of the predicted values and measured values was done and the residual sum of the squares showed the importance of including oxidation and sorption. Sorption was the most important factor to include in predicting the fates of organic chemicals in the sub-surface environment. PMID:22766422

  13. Study of structure-activity relationship of enantiomeric, protonated and deprotonated forms of warfarin via vibrational spectroscopy and DFT calculations

    NASA Astrophysics Data System (ADS)

    Mishra, Alok; Srivastava, Sunil Kumar; Swati, D.

    2013-09-01

    The structure-activity relationship of the anticoagulant drug warfarin were studied by studying two enantiomeric forms (S-form and R-form) of warfarin and its protonated as well as deprotonated structures in aqueous media using density functional theory (DFT). Theoretically computed Raman and IR spectra of all the computed structures were compared and their specific vibrational spectroscopic signatures were discussed. The percentage contributions of individual normal modes of warfarin, which provides direct evidence of the different molecular activity due to change in relative atomic position of atoms in molecule, were investigated through potential energy distribution (PED). The optimized energy and molecular electrostatic potential (MEP) maps show that the S-form of the drug molecules warfarin is energetically more stable than R-form and provides higher docking opportunity for the molecular binding with the receptors in the bio-systems.

  14. Quantitative Structure Activity Relationship for Inhibition of Human Organic Cation/Carnitine Transporter (OCTN2)

    PubMed Central

    Diao, Lei; Ekins, Sean; Polli, James E.

    2010-01-01

    Organic cation/carnitine transporter (OCTN2; SLC22A5) is an important transporter for L-carnitine homeostasis, but can be inhibited by drugs, which may cause L-carnitine deficiency and possibly other OCTN2-mediated drug-drug interactions. One objective was to develop a quantitative structure–activity relationship (QSAR) of OCTN2 inhibitors, in order to predict and identify other potential OCTN2 inhibitors and infer potential clinical interactions. A second objective was to assess two high renal clearance drugs that interact with OCTN2 in vitro (cetirizine and cephaloridine) for possible OCTN2-mediated drug-drug interactions. Using previously generated in vitro data of 22 drugs, a 3D quantitative pharmacophore model and a Bayesian machine learning model were developed. The four pharmacophore features include two hydrophobic groups, one hydrogen-bond acceptor, and one positive ionizable center. The Bayesian machine learning model was developed using simple interpretable descriptors and function class fingerprints of maximum diameter 6 (FCFP_6). An external test set of 27 molecules, including 15 newly identified OCTN2 inhibitors, and a literature test set of 22 molecules were used to validate both models. The computational models afforded good capability to identify structurally diverse OCTN2 inhibitors, providing a valuable tool to predict new inhibitors efficiently. Inhibition results confirmed our previously observed association between rhabdomyolysis and Cmax/Ki ratio. The two high renal clearance drugs cetirizine and cephaloridine were found not to be OCTN2 substrates and their diminished elimination by other drugs is concluded not to be mediated by OCTN2. PMID:20831193

  15. Antiproliferative and apoptotic activities of triterpenoid saponins from the roots of Platycodon grandiflorum and their structure-activity relationships.

    PubMed

    Chun, Jaemoo; Ha, In Jin; Kim, Yeong Shik

    2013-05-01

    The present study was undertaken to investigate the antiproliferative and apoptotic activities of Platycodon saponins, including platycodin D, 2''-O-acetylplatycodin D, 3''-O-acetylplatycodin D, polygalacin D, 2''-O-acetylpolygalacin D, and 3''-O-acetylpolygalacin D, isolated from Platycodon grandiflorum, and prosapogenins which lack the C-3 or C-28 sugar residues, obtained from hydrolysis of platycodin D. We also clarified the structure-activity relationships of these molecules to define structural features that are crucial for the biological activity of Platycodon saponins and prosapogenins. The results showed that all Platycodon saponins had antiproliferative effects on the seven types of cancer cell lines tested. In particular, O-acetylation at the C-2 or C-3 position of rhamnose and dehydroxylation at C-24 increase the compound's cytotoxicity, while the loss of sugar residues linked to C-3 or C-28 dramatically reduced cytotoxicity. This cytotoxicity was associated with apoptosis, which was indicated by DNA fragmentation, phosphatidylserine externalization, and the activation of caspases in AGS cells. Furthermore, Platycodon saponins suppressed the phosphorylation of Akt, which resulted in the inhibition of mTOR and NF-κB signaling following the inhibition of their downstream proteins. In conclusion, six Platycodon saponins have antiproliferative activity, and the presence of sugar residues, an O-acetyl group on the rhamnose, and a methyl group at C-4 contributes to their cytotoxicity and apoptotic activity. These findings may be useful in evaluating the structure-activity relationships of Platycodon saponins and modifying them as a potent apoptosis-inducing agent. PMID:23576176

  16. Structure-Activity Relationships of Novel Salicylaldehyde Isonicotinoyl Hydrazone (SIH) Analogs: Iron Chelation, Anti-Oxidant and Cytotoxic Properties

    PubMed Central

    Potůčková, Eliška; Hrušková, Kateřina; Bureš, Jan; Kovaříková, Petra; Špirková, Iva A.; Pravdíková, Kateřina; Kolbabová, Lucie; Hergeselová, Tereza; Hašková, Pavlína; Jansová, Hana; Macháček, Miloslav; Jirkovská, Anna; Richardson, Vera; Lane, Darius J. R.; Kalinowski, Danuta S.; Richardson, Des R.; Vávrová, Kateřina; Šimůnek, Tomáš

    2014-01-01

    Salicylaldehyde isonicotinoyl hydrazone (SIH) is a lipophilic, tridentate iron chelator with marked anti-oxidant and modest cytotoxic activity against neoplastic cells. However, it has poor stability in an aqueous environment due to the rapid hydrolysis of its hydrazone bond. In this study, we synthesized a series of new SIH analogs (based on previously described aromatic ketones with improved hydrolytic stability). Their structure-activity relationships were assessed with respect to their stability in plasma, iron chelation efficacy, redox effects and cytotoxic activity against MCF-7 breast adenocarcinoma cells. Furthermore, studies assessed the cytotoxicity of these chelators and their ability to afford protection against hydrogen peroxide-induced oxidative injury in H9c2 cardiomyoblasts. The ligands with a reduced hydrazone bond, or the presence of bulky alkyl substituents near the hydrazone bond, showed severely limited biological activity. The introduction of a bromine substituent increased ligand-induced cytotoxicity to both cancer cells and H9c2 cardiomyoblasts. A similar effect was observed when the phenolic ring was exchanged with pyridine (i.e., changing the ligating site from O, N, O to N, N, O), which led to pro-oxidative effects. In contrast, compounds with long, flexible alkyl chains adjacent to the hydrazone bond exhibited specific cytotoxic effects against MCF-7 breast adenocarcinoma cells and low toxicity against H9c2 cardiomyoblasts. Hence, this study highlights important structure-activity relationships and provides insight into the further development of aroylhydrazone iron chelators with more potent and selective anti-neoplastic effects. PMID:25393531

  17. Quantitative structure-activation barrier relationship modeling for Diels-Alder ligations utilizing quantum chemical structural descriptors

    PubMed Central

    2013-01-01

    Background In the present study, we show the correlation of quantum chemical structural descriptors with the activation barriers of the Diels-Alder ligations. A set of 72 non-catalysed Diels-Alder reactions were subjected to quantitative structure-activation barrier relationship (QSABR) under the framework of theoretical quantum chemical descriptors calculated solely from the structures of diene and dienophile reactants. Experimental activation barrier data were obtained from literature. Descriptors were computed using Hartree-Fock theory using 6-31G(d) basis set as implemented in Gaussian 09 software. Results Variable selection and model development were carried out by stepwise multiple linear regression methodology. Predictive performance of the quantitative structure-activation barrier relationship (QSABR) model was assessed by training and test set concept and by calculating leave-one-out cross-validated Q2 and predictive R2 values. The QSABR model can explain and predict 86.5% and 80% of the variances, respectively, in the activation energy barrier training data. Alternatively, a neural network model based on back propagation of errors was developed to assess the nonlinearity of the sought correlations between theoretical descriptors and experimental reaction barriers. Conclusions A reasonable predictability for the activation barrier of the test set reactions was obtained, which enabled an exploration and interpretation of the significant variables responsible for Diels-Alder interaction between dienes and dienophiles. Thus, studies in the direction of QSABR modelling that provide efficient and fast prediction of activation barriers of the Diels-Alder reactions turn out to be a meaningful alternative to transition state theory based computation. PMID:24171724

  18. Structure-activity relationships (SAR) and structure-kinetic relationships (SKR) of pyrrolopiperidinone acetic acids as CRTh2 antagonists.

    PubMed

    Andrés, Miriam; Buil, Maria Antonia; Calbet, Marta; Casado, Oscar; Castro, Jordi; Eastwood, Paul R; Eichhorn, Peter; Ferrer, Manel; Forns, Pilar; Moreno, Imma; Petit, Silvia; Roberts, Richard S

    2014-11-01

    Pyrrolopiperidinone acetic acids (PPAs) were identified as highly potent CRTh2 receptor antagonists. In addition, many of these compounds displayed slow-dissociation kinetics from the receptor. Structure-kinetic relationship (SKR) studies allowed optimisation of the kinetics to give potent analogues with long receptor residence half-lives of up to 23 h. Low permeability was a general feature of this series, however oral bioavailability could be achieved through the use of ester prodrugs. PMID:25437503

  19. Quantitative structure-activity relationships and mixture toxicity of organic chemicals in Photobacterium phosphoreum: the Microtox test

    SciTech Connect

    Hermens, J.; Busser, F.; Leeuwangh, P.; Musch, A.

    1985-02-01

    Quantitative structure-activity relationships were calculated for the inhibition of bioluminescence of Photobacterium phosphoreum by 22 nonreactive organic chemicals. The inhibition was measured using the Microtox test and correlated with the partition coefficient between n-octanol and water (Poct), molar refractivity (MR), and molar volume (MW/d). At log Poct less than 1 and greater than 3, deviations from linearity were observed. Introduction of MR and MW/d improved the quality of the relationships. The influences of MR or MW/d may be related with an interaction of the tested chemicals to the enzyme system which produces the light emission. The sensitivity of the Microtox test to the 22 tested compounds is comparable to a 14-day acute mortality test with guppies for chemicals with log Poct less than 4. The inhibition of bioluminescence by a mixture of the tested compounds was slightly less than was expected in case of concentration addition. The Microtox test can give a good estimate of the total aspecific minimum toxicity of polluted waters. When rather lipophilic compounds or pollutants with more specific modes of action are present, this test will underestimate the toxicity to other aquatic life.

  20. Parental Alcohol Use, Family Relationship Quality, Self-Esteem, and Depression in College Students.

    ERIC Educational Resources Information Center

    Kashubeck, Susan; Christensen, Sue A.

    1995-01-01

    Family relationship quality, not parental alcohol use, predicted levels of depression and self-esteem in 201 college students. Witnessing spousal abuse related to increased depression in adult children of alcoholics, whole poorer family relationship quality was associated with lower self-esteem, suggesting the experience of paternal alcoholism is…

  1. Moderators of the Relationship between Physical Activity and Alcohol Consumption in College Students

    ERIC Educational Resources Information Center

    Buscemi, Joanna; Martens, Matthew P.; Murphy, James G.; Yurasek, Ali M.; Smith, Ashley E.

    2011-01-01

    Objective: Among college students, several studies have found a positive relationship between physical activity and alcohol use. The current study tested gender, Greek status, and ethnicity as potential moderators of the physical activity-alcohol use relationship. Participants: Participants were college freshmen (n = 310) endorsing alcohol/drug…

  2. Relationships of impulsiveness and depressive symptoms in alcohol dependence

    PubMed Central

    Jakubczyk, Andrzej; Klimkiewicz, Anna; Topolewska-Wochowska, Aleksandra; Serafin, Piotr; Sadowska-Mazuryk, Joanna; Pupek-Pyzioł, Julia; Brower, Kirk J.; Wojnar, Marcin

    2011-01-01

    Background Depressive symptoms as well as high levels of impulsivity are subjects of special interest in alcohol dependence, as these factors are considered to influence the course of this disorder. However, until now mutual relationships between impulsivity and depression have not been investigated thoroughly in alcohol-dependent patients. Methods By means of the Barratt Impulsiveness Scale (BIS-11) and stop-signal task, levels of impulsivity among 304 alcohol-dependent patients were measured. The stop-signal task was used as a manipulation-free method of estimating the level of behavioral impulsiveness, and the BIS-11 is a self report measure of global as well as cognitive impulsivity. Patients were also asked to complete the Beck Depression Inventory (BDI) and Hopelessness Scale (BHS). The results were analyzed in order to examine relationships between impulsiveness and depressive symptoms. Results Statistical analyses revealed significant associations between impulsiveness and severity of depressive symptoms. Individuals with higher scores on the BDI were more impulsive on the BIS-11, whereas patients with higher scores on the BHS were more impulsive on both the stop-signal task and BIS-11. The strongest correlations were found with the attention impulsivity subscale of BIS-11. Adjusting for other variables, a linear regression analysis revealed that cognitive impulsivity was the strongest predictor of depression severity. Limitations The main limitation of the study is a not fully representative sample, with exclusion of patients with active mood disorders Conclusions The results indicate a strong association between depressive symptoms and impulsivity in alcohol-dependent patients, and suggest an important distinction between hopelessness and other depressive symptoms. PMID:22030134

  3. Structure-activity relationship study of biflavonoids on the Dengue virus polymerase DENV-NS5 RdRp.

    PubMed

    Coulerie, Paul; Nour, Mohammed; Maciuk, Alexandre; Eydoux, Cécilia; Guillemot, Jean-Claude; Lebouvier, Nicolas; Hnawia, Edouard; Leblanc, Karine; Lewin, Guy; Canard, Bruno; Figadère, Bruno

    2013-09-01

    Dengue virus is the world's most prevalent human pathogenic arbovirus. There is currently no treatment or vaccine, and solutions are urgently needed. We previously demonstrated that biflavonoids from Dacrydium balansae, an endemic gymnosperm from New Caledonia, are potent inhibitors of the Dengue virus NS5 RNA-dependent RNA polymerase. Herein we describe the structure-activity relationship study of 23 compounds: biflavonoids from D. balansae (1-4) and from D. araucarioides (5-10), hexamethyl-amentoflavone (11), cupressuflavone (12), and apigenin derivatives (13-23). We conclude that 1) over the four different biflavonoid skeletons tested, amentoflavone (1) and robustaflavone (5) are the most promising ones for antidengue drug development, 2) the number and position of methyl groups on the biflavonoid moiety modulate their inhibition of Dengue virus NS5 RNA-dependent RNA polymerase, and 3) the degree of oxygenation of flavonoid monomers influences their antidengue potential. Sotetsuflavone (8), with an IC50 = 0.16 µM, is the most active compound of this series and is the strongest inhibitor of the Dengue virus NS5 RNA-dependent RNA polymerase described in the literature. PMID:23929244

  4. CLEFMA- An Anti-Proliferative Curcuminoid from Structure Activity Relationship Studies on 3,5-bis(benzylidene)-4-piperidones

    PubMed Central

    Lagisetty, Pallavi; Vilekar, Prachi; Sahoo, Kaustuv; Anant, Shrikant; Awasthi, Vibhudutta

    2010-01-01

    3,5-bis(benzylidene)-4-piperidones are being advanced as synthetic analogs of curcumin for anticancer and anti-inflammatory properties. We performed structure-activity relationship studies, by testing several synthesized 3,5-bis(benzylidene)-4-piperidones for anti-proliferative activity in lung adenocarcinoma H441 cells. Compared to the lead compound 1, or 3,5-bis(2-fluorobenzylidene)-4-piperidone, five compounds were found to be more potent (IC50 < 30 μM), and sixteen compounds possessed reduced cell-killing efficacy (IC50 > 50 μM). Based on the observations, we synthesized 4-[3,5-bis(2-chlorobenzylidene-4-oxo-piperidine-1-yl)-4-oxo-2-butenoic acid] (29 or CLEFMA) as a novel analog of 1. CLEFMA was evaluated for anti-proliferative activity in H441 cells, and was found to be several folds more potent than compound 1. We did not find apoptotic cell population in flow cytometry, and the absence of apoptosis was confirmed by the lack of caspase cleavage. The electron microscopy of H441cells indicated that CLEFMA and compound 1 induce autophagic cell death that was inhibited by specific autophagy inhibitor 3-methyladenine. The results suggest that the potent and novel curcuminoid, CLEFMA, offers an alternative mode of cell death in apoptosis-resistant cancers. PMID:20638855

  5. Design, synthesis and structure-activity relationships of novel 4-phenoxyquinoline derivatives containing pyridazinone moiety as potential antitumor agents.

    PubMed

    Zhou, Shunguang; Liao, Huimin; He, Chao; Dou, Yanan; Jiang, Mingyan; Ren, Lixiang; Zhao, Yanfang; Gong, Ping

    2014-08-18

    A series of novel 4-phenoxyquinoline derivatives containing pyridazinone moiety were synthesized and evaluated for their in vitro cytotoxic activity against five cancer cell lines (HT-29, H460, A549, MKN-45, and U87MG). Most of the compounds exhibited moderate-to-significant cytotoxicity and high selectivity against one or more cell lines. Compounds 15a, 20a, 15b, 15c, 20d, and 16e were further examined for their inhibitory activity against c-Met kinase. The most promising compound 15a (c-Met half-maximal inhibitory concentration [IC50] = 2.15 nM) showed remarkable cytotoxicity against HT-29, H460, and A549 cell lines with IC50 values of 0.10 μM, 0.13 μM, and 0.05 μM, respectively, and thus it was 1.5- to 2.3-fold more potent than foretinib. Their preliminary structure-activity relationships (SARs) studies indicate that electron-withdrawing groups on the terminal phenyl rings are beneficial for improving the antitumor activity. PMID:24996144

  6. A Quantitative Structure Activity Relationship for acute oral toxicity of pesticides on rats: Validation, domain of application and prediction.

    PubMed

    Hamadache, Mabrouk; Benkortbi, Othmane; Hanini, Salah; Amrane, Abdeltif; Khaouane, Latifa; Si Moussa, Cherif

    2016-02-13

    Quantitative Structure Activity Relationship (QSAR) models are expected to play an important role in the risk assessment of chemicals on humans and the environment. In this study, we developed a validated QSAR model to predict acute oral toxicity of 329 pesticides to rats because a few QSAR models have been devoted to predict the Lethal Dose 50 (LD50) of pesticides on rats. This QSAR model is based on 17 molecular descriptors, and is robust, externally predictive and characterized by a good applicability domain. The best results were obtained with a 17/9/1 Artificial Neural Network model trained with the Quasi Newton back propagation (BFGS) algorithm. The prediction accuracy for the external validation set was estimated by the Q(2)ext and the root mean square error (RMS) which are equal to 0.948 and 0.201, respectively. 98.6% of external validation set is correctly predicted and the present model proved to be superior to models previously published. Accordingly, the model developed in this study provides excellent predictions and can be used to predict the acute oral toxicity of pesticides, particularly for those that have not been tested as well as new pesticides. PMID:26513561

  7. Structure-activity relationships of anthraquinone derivatives derived from bromaminic acid as inhibitors of ectonucleoside triphosphate diphosphohydrolases (E-NTPDases)

    PubMed Central

    Baqi, Younis; Weyler, Stefanie; Iqbal, Jamshed; Zimmermann, Herbert

    2008-01-01

    Reactive blue 2 (RB-2) had been characterized as a relatively potent ectonucleoside triphosphate diphosphohydrolase (E-NTPDase) inhibitor with some selectivity for NTPDase3. In search for the pharmacophore and to analyze structure-activity relationships we synthesized a series of truncated derivatives and analogs of RB-2, including 1-amino-2-sulfo-4-ar(alk)ylaminoanthraquinones, 1-amino-2-methyl-4-arylaminoanthraquinones, 1-amino-4-bromoanthraquinone 2-sulfonic acid esters and sulfonamides, and bis-(1-amino-4-bromoanthraquinone) sulfonamides, and investigated them in preparations of rat NTPDase1, 2, and 3 using a capillary electrophoresis assay. Several 1-amino-2-sulfo-4-ar(alk)ylaminoanthraquinone derivatives inhibited E-NTPDases in a concentration-dependent manner. The 2-sulfonate group was found to be required for inhibitory activity, since 2-methyl-substituted derivatives were inactive. 1-Amino-2-sulfo-4-p-chloroanilinoanthraquinone (18) was identified as a nonselective competitive blocker of NTPDases1, 2, and 3 (Ki 16–18 μM), while 1-amino-2-sulfo-4-(2-naphthylamino)anthraquinone (21) was a potent inhibitor with preference for NTPDase1 (Ki 0.328 μM) and NTPDase3 (Ki 2.22 μM). Its isomer, 1-amino-2-sulfo-4-(1-naphthylamino)anthraquinone (20), was a potent and selective inhibitor of rat NTPDase3 (Ki 1.5 μM). PMID:18528783

  8. Structure-Activity Relationships of Antimicrobial Gallic Acid Derivatives from Pomegranate and Acacia Fruit Extracts against Potato Bacterial Wilt Pathogen.

    PubMed

    Farag, Mohamed A; Al-Mahdy, Dalia A; Salah El Dine, Riham; Fahmy, Sherifa; Yassin, Aymen; Porzel, Andrea; Brandt, Wolfgang

    2015-06-01

    Bacterial wilts of potato, tomato, pepper, and or eggplant caused by Ralstonia solanacearum are among the most serious plant diseases worldwide. In this study, the issue of developing bactericidal agents from natural sources against R. solanacearum derived from plant extracts was addressed. Extracts prepared from 25 plant species with antiseptic relevance in Egyptian folk medicine were screened for their antimicrobial properties against the potato pathogen R. solancearum by using the disc-zone inhibition assay and microtitre plate dilution method. Plants exhibiting notable antimicrobial activities against the tested pathogen include extracts from Acacia arabica and Punica granatum. Bioactivity-guided fractionation of A. arabica and P. granatum resulted in the isolation of bioactive compounds 3,5-dihydroxy-4-methoxybenzoic acid and gallic acid, in addition to epicatechin. All isolates displayed significant antimicrobial activities against R. solanacearum (MIC values 0.5-9 mg/ml), with 3,5-dihydroxy-4-methoxybenzoic acid being the most effective one with a MIC value of 0.47 mg/ml. We further performed a structure-activity relationship (SAR) study for the inhibition of R. solanacearum growth by ten natural, structurally related benzoic acids. PMID:26080741

  9. Dihydro-β-agarofuran sesquiterpenes from celastraceae species as anti-tumour-promoting agents: Structure-activity relationship.

    PubMed

    Núñez, Marvin J; Jiménez, Ignacio A; Mendoza, Cristina R; Chavez-Sifontes, Marvin; Martinez, Morena L; Ichiishi, Eiichiro; Tokuda, Ryo; Tokuda, Harukuni; Bazzocchi, Isabel L

    2016-03-23

    Inhibition of tumour promotion in multistage chemical carcinogenesis is considered a promising strategy for cancer chemoprevention. In an ongoing investigation of bioactive secondary metabolites from Celastraceae species, five new dihydro-β-agarofuran sesquiterpenes (1-5), named Chiapens A-E, and seventeen known ones, were isolated from Maytenus chiapensis. Their structures were elucidated by extensive NMR spectroscopic and mass spectrometric techniques, and their absolute configurations were determined by circular dichroism studies, chemical correlations and biogenic means. The isolated compounds, along with twenty known sesquiterpenes, previously isolated from Zinowiewia costaricensis, have been tested for their inhibitory effects on Epstein-Barr virus early antigen (EBV-EA) activation induced by 12-O-tetradecanoylphorpol-13-acetate (TPA). Thirty three compounds from this series showed stronger effects than that of β-carotene, the reference inhibitor. The structure-activity relationship (SAR) analysis revealed that the type of substituent, in particular at the C-1 position of the sesquiterpene scaffold, was able to modulate the anti-tumour promoting activity. Compounds 3, 6, and 33 showed significant effects in an in vivo two-stage mouse-skin carcinogenesis model. PMID:26854381

  10. Synthetic cannabinoids: In silico prediction of the cannabinoid receptor 1 affinity by a quantitative structure-activity relationship model.

    PubMed

    Paulke, Alexander; Proschak, Ewgenij; Sommer, Kai; Achenbach, Janosch; Wunder, Cora; Toennes, Stefan W

    2016-03-14

    The number of new synthetic psychoactive compounds increase steadily. Among the group of these psychoactive compounds, the synthetic cannabinoids (SCBs) are most popular and serve as a substitute of herbal cannabis. More than 600 of these substances already exist. For some SCBs the in vitro cannabinoid receptor 1 (CB1) affinity is known, but for the majority it is unknown. A quantitative structure-activity relationship (QSAR) model was developed, which allows the determination of the SCBs affinity to CB1 (expressed as binding constant (Ki)) without reference substances. The chemically advance template search descriptor was used for vector representation of the compound structures. The similarity between two molecules was calculated using the Feature-Pair Distribution Similarity. The Ki values were calculated using the Inverse Distance Weighting method. The prediction model was validated using a cross validation procedure. The predicted Ki values of some new SCBs were in a range between 20 (considerably higher affinity to CB1 than THC) to 468 (considerably lower affinity to CB1 than THC). The present QSAR model can serve as a simple, fast and cheap tool to get a first hint of the biological activity of new synthetic cannabinoids or of other new psychoactive compounds. PMID:26795018