1
|
Fathimunnisa M, Manikandan H, Neelakandan K, Rajendra Prasad N, Selvanayagam S, Sridhar B. Synthesis, characterization, biological evaluation and docking studies of 2′-[(2″,4″-difluorobiphenyl-4-yl)carbonyl]-1′-aryl-1′,2′,5′,6′,7′,7a′-hexahydrospiro[indole-3,3′-pyrrolizin]-2(1H)-ones. J Mol Struct 2016. [DOI: 10.1016/j.molstruc.2016.06.012] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
2
|
Çabuk A, Sidir YG, Aytar P, Gedikli S, Sidir İ. Dechlorination of chlorinated compounds by Trametes versicolor ATCC 200801 crude laccase and quantitative structure-activity relationship of toxicity. JOURNAL OF ENVIRONMENTAL SCIENCE AND HEALTH. PART A, TOXIC/HAZARDOUS SUBSTANCES & ENVIRONMENTAL ENGINEERING 2012; 47:1938-1947. [PMID: 22755541 DOI: 10.1080/03601234.2012.676517] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Chlorinated compounds constitute an important class of xenobiotics. Crude laccase was produced using Trametes versicolor ATCC (200801) in potato dextrose broth, with wheat bran as an inducing medium, and its ability to dechlorinate eight compounds was determined. The compounds were 2-chlorophenol, 4-chlorophenol, 2,4-dichlorophenol, 2,6-dichlorophenol, 2,4,5-trichlorophenol, 2,4,6-trichlorophenol, heptachlor and pentachlorophenol. A range of parameters for the dechlorination of some compounds was tested, including incubation period, pH, initial substrate concentration, temperature, and enzyme quantity. The oxygen consumption was determined during each dechlorination process, under pre-determined optimum conditions. The changes in chemical structure of the compounds were also determined, by using FTIR analysis, following dechlorination of test chlorophenolics. Strong interactions were found to lead to the reactivity of hydroxyl groups in some cases and chlorine atoms were released from the benzene ring. The changes in compound toxicity were monitored before and after enzymatic treatment, using Microtox. Quantitative structure-activity relationships for the toxicity of the chlorinated compounds were developed. Consequently, the toxic activity of the test compounds was controlled by electrophilic index and electronic properties.
Collapse
Affiliation(s)
- Ahmet Çabuk
- Department of Biology, Eskişehir Osmangazi University, Eskişehir, Turkey.
| | | | | | | | | |
Collapse
|
3
|
Punt A, Schiffelers MJWA, Jean Horbach G, van de Sandt JJM, Groothuis GMM, Rietjens IMCM, Blaauboer BJ. Evaluation of research activities and research needs to increase the impact and applicability of alternative testing strategies in risk assessment practice. Regul Toxicol Pharmacol 2011; 61:105-14. [PMID: 21782875 DOI: 10.1016/j.yrtph.2011.06.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2010] [Revised: 06/07/2011] [Accepted: 06/29/2011] [Indexed: 11/20/2022]
Abstract
The present paper aims at identifying strategies to increase the impact and applicability of alternative testing strategies in risk assessment. To this end, a quantitative and qualitative literature evaluation was performed on (a) current research efforts in the development of in vitro methods aiming for alternatives to animal testing, (b) the possibilities and limitations of in vitro methods for regulatory purposes and (c) the potential of physiologically-based kinetic (PBK) modeling to improve the impact and applicability of in vitro methods in risk assessment practice. Overall, the evaluation showed that the focus of state-of-the-art research activities does not seem to be optimally directed at developing in vitro alternatives for those endpoints that are most animal-demanding, such as reproductive and developmental toxicity, and carcinogenicity. A key limitation in the application of in vitro alternatives to such systemic endpoints is that in vitro methods do not provide so-called points of departure, necessary for regulators to set safe exposure limits. PBK-modeling could contribute to overcoming this limitation by providing a method that allows extrapolation of in vitro concentration-response curves to in vivo dose-response curves. However, more proofs of principle are required.
Collapse
Affiliation(s)
- Ans Punt
- Institute for Risk Assessment Sciences (IRAS), Utrecht University, P.O. Box 80176, 3508 TD Utrecht, The Netherlands.
| | | | | | | | | | | | | |
Collapse
|
4
|
Chan K, Jensen NS, Silber PM, O'Brien PJ. Structure–activity relationships for halobenzene induced cytotoxicity in rat and human hepatoctyes. Chem Biol Interact 2007; 165:165-74. [PMID: 17229414 DOI: 10.1016/j.cbi.2006.12.004] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2006] [Revised: 12/04/2006] [Accepted: 12/07/2006] [Indexed: 11/19/2022]
Abstract
Halobenzenes are ubiquitous environmental contaminants, which are hepatotoxic in both rodents and humans. The molecular mechanism of halobenzene hepatotoxicity was investigated using Quantitative structure-activity relationships (QSAR) and accelerated cytotoxicity mechanism screening (ACMS) techniques in rat and human hepatocytes. The usefulness of isolated hepatocytes for prediciting in vivo xenobiotic toxicity was reassessed by correlating the LC(50) of 12 halobenzene congeners in phenobarbital (PB) induced rat hepatocytes in vitro determined by ACMS to the hepatotoxicities reported in vivo in PB-induced male Sprague-Dawely (SD) rats. A high correlation (r(2)=0.90) confirmed the application of hepatocytes as a "gold standard" for toxicity testing in vitro. QSARs were derived to determine the physico-chemcial variables that govern halobenzene toxicity in PB-induced rat, normal rat and human hepatocytes. We found that toxicity in normal rat and normal human hepatocytes both strongly correlate with hydrophobicity (logP), ease of oxidation (E(HOMO), energy of the highest molecular orbital) and on the asymmetric charge distribution according to arrangement of halogen substituents (dipole moment, mu). This suggests that halobenzene interaction with cytochrome P450 for oxidation is the metabolic activating path for toxicity and is similar in both species. In PB-induced rat hepatocytes the QSAR derivation is changed, where halobenzene toxicity strongly correlates to logP and dipole moment, but not E(HOMO). The changed QSAR suggests that oxidation is no longer the rate-limiting step in the cytotoxic mechanism when CYP2B/3A levels are increased, confirming CYP450 oxidation as the metabolic activating step under normal conditions.
Collapse
Affiliation(s)
- Katie Chan
- University of Toronto, Faculty of Pharmacy, Toronto, Ont., Canada M5S 2S2
| | | | | | | |
Collapse
|
5
|
Lewis DFV, Lake BG, Ito Y, Anzenbacher P. Quantitative structure-activity relationships (QSARs) within cytochromes P450 2B (CYP2B) subfamily enzymes: the importance of lipophilicity for binding and metabolism. ACTA ACUST UNITED AC 2006; 21:213-31. [PMID: 16841514 DOI: 10.1515/dmdi.2006.21.3-4.213] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The results of qualitative structure-activity relationship (QSAR) analysis are reported for several series of compounds which act as substrates for mammalian CYP2B subfamily enzymes, together with a homologous series of aliphatic primary amines which are known to inhibit CYP2B enzymes. It is found that the compound lipophilicity in the form of the log P value (where P is the octanol/water partition coefficient) is related, either linearly or quadratically, to equilibrium constants of inhibition (Ki), binding (Ks) or metabolism (Km) depending on the series of compounds in question. In some instances, the difference between frontier orbital energy levels (deltaE) also features in several of the log P expressions with biological activity. Also present in a small number of correlations are parameters which are likely to be related to logP: namely, Rm, which is the partitioning factor derived from thin layer chromatography (TLC) retention times, and also the compound molecular weight (Mr). All of these three parameters ((log P, Rm and Mr) are thought to be related to the compound's ability to desolvate the P450 active site when they bind to the enzyme. Although the linear relationships between lipophilicity and CYP2B-related activity point to a major role for desolvation of the enzyme binding site in the overall interaction, it is noted that there may be an optimal log P value displayed by preferred substrates as shown by parabolic relationships with this lipophilic parameter. In addition, there is a remarkable similarity in the coefficients for the log P term of any QSAR expression, which suggests that the hydrophobicity of CYP2B active sites may be broadly equivalent between the various mammalian species.
Collapse
Affiliation(s)
- David F V Lewis
- School of Biomedical and Molecular Sciences, University of Surrey, Guildford, Surrey, UK.
| | | | | | | |
Collapse
|
6
|
Lewis DFV. Quantitative structure-activity relationships (QSARs) within the cytochrome P450 system: QSARs describing substrate binding, inhibition and induction of P450s. Inflammopharmacology 2004; 11:43-73. [PMID: 15035734 DOI: 10.1163/156856003321547112] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Quantitative structure-activity relationships (QSARs) within substrates, inducers and inhibitors of cytochromes P450 involved in xenobiotic metabolism are reported, together with QSARs associated with induction, inhibition and metabolic rate. The importance of frontier orbitals and shape descriptors, such as planarity (estimated by the area/depth(2) parameter) and rectangularity (estimated by the length/width parameter) is discussed, particularly in the context of the COMPACT system which discriminates between several P450 families associated with the activation and detoxication of xenobiotics. The use of parameters, particularly those derived from homology modelling of mammalian (especially human) P450s that are involved in exogenous metabolism, in generating QSARs for P450 substrates is discussed in the context of explaining differences in the binding affinities of human P450 substrates which are pharmacologically active.
Collapse
Affiliation(s)
- David F V Lewis
- School of Biomedical and Life Sciences, University of Surrey, Guildford, Surrey, GU2 7XH, UK.
| |
Collapse
|
7
|
Affiliation(s)
- Corwin Hansch
- Department of Chemistry, Pomona College, Claremont, California 91711, USA.
| | | | | | | |
Collapse
|
8
|
Lewis DFV, Dickins M. Factors influencing rates and clearance in P450-mediated reactions: QSARs for substrates of the xenobiotic-metabolizing hepatic microsomal P450s. Toxicology 2002; 170:45-53. [PMID: 11750082 DOI: 10.1016/s0300-483x(01)00524-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Various contributory factors associated with the kinetics of cytochrome P450-mediated catalytic activity and the metabolic clearance of drug substrates are discussed and evaluated, based on literature data and physicochemical parameters. Quantitative relationships between molecular structure and biological activity for several series of P450 substrates are presented which point to certain commonalities in P450-catalyzed reactions. In particular, it appears that frontier orbital energies are especially important for the estimation of reaction rates and clearance for many P450 substrates, although occasionally these have to be combined with other descriptors, such as compound lipophilicity (in the form of logP or logD(74)).
Collapse
Affiliation(s)
- D F V Lewis
- School of Biomedical and Life Sciences, University of Surrey, Guildford, GU2 7XH, Surrey, UK.
| | | |
Collapse
|
9
|
Thanikaivelan P, Subramanian V, Raghava Rao J, Unni Nair B. Application of quantum chemical descriptor in quantitative structure activity and structure property relationship. Chem Phys Lett 2000. [DOI: 10.1016/s0009-2614(00)00488-7] [Citation(s) in RCA: 168] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
|
10
|
Affiliation(s)
- S Ekins
- Department of Drug Disposition, Lilly Research Laboratories, Eli Lilly and Co., Lilly Corporate Center, Indianapolis, Indiana 46285, USA
| | | |
Collapse
|
11
|
Lewis DF. Frontier orbitals in chemical and biological activity: quantitative relationships and mechanistic implications. Drug Metab Rev 1999; 31:755-816. [PMID: 10461548 DOI: 10.1081/dmr-100101943] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Affiliation(s)
- D F Lewis
- School of Biological Sciences, University of Surrey, Guildford, UK
| |
Collapse
|
12
|
Affiliation(s)
- D F Lewis
- Molecular Toxicology Group, School of Biological Sciences, University of Surrey, Guilford, UK
| | | |
Collapse
|
13
|
Lewis DF, Ioannides C, Parke DV. An improved and updated version of the compact procedure for the evaluation of P450-mediated chemical activation. Drug Metab Rev 1998; 30:709-37. [PMID: 9844807 DOI: 10.3109/03602539808996328] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
- D F Lewis
- School of Biological Sciences, University of Surrey, Guildford, UK
| | | | | |
Collapse
|
14
|
Lewis DF, Eddershaw PJ, Dickins M, Tarbit MH, Goldfarb PS. Structural determinants of cytochrome P450 substrate specificity, binding affinity and catalytic rate. Chem Biol Interact 1998; 115:175-99. [PMID: 9851289 DOI: 10.1016/s0009-2797(98)00068-4] [Citation(s) in RCA: 69] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
The structural characteristics of cytochrome P450 substrates are summarised, showing that molecular descriptors can discriminate between chemicals of differing P450 isozyme specificity. Procedures for the estimation of P450 substrate binding interaction energies and rates of metabolism are described, providing specific examples in both individual compounds binding to P450s, including those of known crystal structure, and within series of structurally related chemicals. It is demonstrated that binding energy components are primarily hydrophobic/desolvation and electrostatic/hydrogen-bonded in nature, whereas electronic factors are of importance in determining variations in reaction rates. It is thus shown that the prediction of P450 substrate binding affinities and catalytic rates may be feasible, provided that sufficient structural information is available for the relevant enzyme-substrate complex.
Collapse
Affiliation(s)
- D F Lewis
- School of Biological Sciences, University of Surrey, Guildford, UK.
| | | | | | | | | |
Collapse
|
15
|
Hansch C, Gao H. Comparative QSAR: Radical Reactions of Benzene Derivatives in Chemistry and Biology. Chem Rev 1997; 97:2995-3060. [PMID: 11851484 DOI: 10.1021/cr9601021] [Citation(s) in RCA: 112] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Affiliation(s)
- Corwin Hansch
- Department of Chemistry, Pomona College, Claremont, California 91711
| | | |
Collapse
|
16
|
Lewis DF. Quantitative structure-activity relationships in substrates, inducers, and inhibitors of cytochrome P4501 (CYP1). Drug Metab Rev 1997; 29:589-650. [PMID: 9262943 DOI: 10.3109/03602539709037593] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- D F Lewis
- Molecular Toxicology Research Group, School of Biological Sciences, University of Surrey, Guildford, UK
| |
Collapse
|
17
|
Lewis DF, Bird MG, Parke DV. Molecular modelling of CYP2E1 enzymes from rat, mouse and man: an explanation for species differences in butadiene metabolism and potential carcinogenicity, and rationalization of CYP2E substrate specificity. Toxicology 1997; 118:93-113. [PMID: 9129165 DOI: 10.1016/s0300-483x(96)03583-4] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Molecular modelling of substrates of cytochrome P4502E1 (CYP2E1) within the putative active site region of CYP2E1 constructed from the CYP102 crystal structure is reported. Structural characteristics of CYP2E1 substrates, such as molecular size, energy levels and polarity, calculated via molecular orbital procedures provide correlations with toxicity and carcinogenicity; and species differences in CYP2E1-mediated metabolism are rationalized in terms of interactions with putative active site amino acid residues, including Thr-437 and Phe-181. In particular, the activation of buta-1,3-diene can be explained by active site modelling with CYP2E1 enzymes sequenced from rat, mouse and man, where there is a non-conservative change T437H between rodent and human isozymes, together with a conservative change I438V between mouse and rat CYP2E1.
Collapse
Affiliation(s)
- D F Lewis
- Molecular Toxicology Group, Centre for Toxicology, School of Biological Sciences, University of Surrey, Guildford, UK
| | | | | |
Collapse
|
18
|
Kourounakis AP, Rekka EA, Kourounakis PN. Effect of guaiazulene on some cytochrome P450 activities. Implication in the metabolic activation and hepatotoxicity of paracetamol. Arch Pharm (Weinheim) 1997; 330:7-11. [PMID: 9112807 DOI: 10.1002/ardp.19973300103] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The in vitro and in vivo effect of guaiazulene, a natural azulene derivative, on rat hepatic cytochrome P450 (CYP) is investigated. Furthermore, paracetamol hepatotoxicity is induced in rats and the activity of specific cytochrome P450 forms, involved in the metabolic activation of paracetamol to the toxic metabolite N-acetyl-p-benzoquinone imine (NAPQI) is examined, after the administration of guaiazulene, using diagnostic cytochrome P450 substrates. It is found that guaiazulene inhibited considerably CYP1A2 and CYP2B1 and had a weak effect on CYP1A1 in rat hepatic microsomal fractions. Guaiazulene administered to rats did not produce any macroscopic toxic effect and caused no change of liver weight, microsomal protein and total cytochrome P450 content. Guaiazulene inhibited CYP1A2 activity in rats with or without paracetamol intoxication. Considering that CYP1A2 participates in the formation of NAPQI, as well as in the metabolic activation of several toxic and carcinogenic compounds, these results, in combination with the antioxidant activity of guaiazulene that we have found in previous investigations, indicate potential useful applications of guaiazulene.
Collapse
Affiliation(s)
- A P Kourounakis
- Department of Pharmaceutical Chemistry, School of Pharmacy, Aristotelian University of Thessaloniki, Greece
| | | | | |
Collapse
|
19
|
Karelson M, Lobanov VS, Katritzky AR. Quantum-Chemical Descriptors in QSAR/QSPR Studies. Chem Rev 1996; 96:1027-1044. [PMID: 11848779 DOI: 10.1021/cr950202r] [Citation(s) in RCA: 925] [Impact Index Per Article: 33.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Mati Karelson
- Center for Heterocyclic Compounds, Department of Chemistry, University of Florida, P.O. Box 117200, Gainesville, Florida 32611-7200
| | | | | |
Collapse
|