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Hamburger M. HPLC-based activity profiling for pharmacologically and toxicologically relevant natural products - principles and recent examples. PHARMACEUTICAL BIOLOGY 2019; 57:328-334. [PMID: 31057026 PMCID: PMC6507960 DOI: 10.1080/13880209.2019.1606261] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Accepted: 04/02/2019] [Indexed: 05/30/2023]
Abstract
CONTEXT Discovery of pharmacologically active natural products as starting points for drug development remains important and, for reasons of consumer safety, the identification of toxicologically relevant compounds in herbal drugs. OBJECTIVE To explain, with the aid of relevant examples from our own research, how these goals can be achieved. METHODS An in-house technology platform comprising pre-formatted extract libraries in 96-well format, miniaturized tracking of activity in extracts via HPLC-activity profiling, structure elucidation with microprobe NMR, and in vitro and in vivo pharmacological methods were used. RESULTS Piperine was identified as a new scaffold for allosteric GABAA receptor modulators with in vivo activity that interacts at a benzodiazepine-independent binding site. Selectivity and potency were improved by iterative optimization towards synthetic piperine analogues. Dehydroevodiamine and hortiamine from the traditional Chinese herbal drug Evodiae fructus were identified as potent hERG channel blockers in vitro. The compounds induced torsades de pointes arrhythmia in animal models. CONCLUSIONS The allosteric binding site for piperine analogues remains to be characterized and cardiac risks of herbal drugs need to be further evaluated to ensure consumer safety.
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Affiliation(s)
- Matthias Hamburger
- Pharmaceutical Biology, Pharmacenter, University of Basel, Basel, Switzerland
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Atwood CS, Ekstein SF. Human versus non-human sex steroid use in hormone replacement therapies part 1: Preclinical data. Mol Cell Endocrinol 2019; 480:12-35. [PMID: 30308266 DOI: 10.1016/j.mce.2018.10.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Revised: 03/12/2018] [Accepted: 10/04/2018] [Indexed: 11/24/2022]
Abstract
Prior to 2002, hormone replacement therapy (HRT) was considered to be an important component of postmenopausal healthcare. This was based on a plethora of basic, epidemiological and clinical studies demonstrating the health benefits of supplementation with human sex steroids. However, adverse findings from the Women's Health Initiative (WHI) studies that examined the 2 major forms of HRT in use in the US at that time - Premarin (conjugated equine estrogens; CEE) and Prempro (CEE + medroxyprogesterone acetate; MPA), cast a shadow over the use of any form of HRT. Here we review the biochemical and physiological differences between the non-human WHI study hormones - CEE and MPA, and their respective human counterparts 17β-estradiol (E2) and progesterone (P4). Preclinical data from the last 30 years demonstrate clear differences between human and non-human sex steroids on numerous molecular, physiological and functional parameters in brain, heart and reproductive tissue. In contrast to CEE supplementation, which is not always detrimental although certainly not as optimal as E2 supplementation, MPA is clearly not equivalent to P4, having detrimental effects on cognitive, cardiac and reproductive function. Moreover, unlike P4, MPA is clearly antagonistic of the positive effects of E2 and CEE on tissue function. These data indicate that minor chemical changes to human sex steroids result in physiologically distinct actions that are not optimal for tissue health and functioning.
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Affiliation(s)
- Craig S Atwood
- Division of Geriatrics and Gerontology, Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, USA; Geriatric Research, Education and Clinical Center, Veterans Administration Hospital, Madison, WI, 53705, USA; School of Exercise, Biomedical and Health Sciences, Edith Cowan University, Joondalup, 6027, WA, Australia.
| | - Samuel F Ekstein
- Division of Geriatrics and Gerontology, Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, USA
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Bolton JL, Dunlap T. Formation and Biological Targets of Quinones: Cytotoxic versus Cytoprotective Effects. Chem Res Toxicol 2016; 30:13-37. [PMID: 27617882 PMCID: PMC5241708 DOI: 10.1021/acs.chemrestox.6b00256] [Citation(s) in RCA: 248] [Impact Index Per Article: 31.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Quinones represent a class of toxicological intermediates, which can create a variety of hazardous effects in vivo including, acute cytotoxicity, immunotoxicity, and carcinogenesis. In contrast, quinones can induce cytoprotection through the induction of detoxification enzymes, anti-inflammatory activities, and modification of redox status. The mechanisms by which quinones cause these effects can be quite complex. The various biological targets of quinones depend on their rate and site of formation and their reactivity. Quinones are formed through a variety of mechanisms from simple oxidation of catechols/hydroquinones catalyzed by a variety of oxidative enzymes and metal ions to more complex mechanisms involving initial P450-catalyzed hydroxylation reactions followed by two-electron oxidation. Quinones are Michael acceptors, and modification of cellular processes could occur through alkylation of crucial cellular proteins and/or DNA. Alternatively, quinones are highly redox active molecules which can redox cycle with their semiquinone radical anions leading to the formation of reactive oxygen species (ROS) including superoxide, hydrogen peroxide, and ultimately the hydroxyl radical. Production of ROS can alter redox balance within cells through the formation of oxidized cellular macromolecules including lipids, proteins, and DNA. This perspective explores the varied biological targets of quinones including GSH, NADPH, protein sulfhydryls [heat shock proteins, P450s, cyclooxygenase-2 (COX-2), glutathione S-transferase (GST), NAD(P)H:quinone oxidoreductase 1, (NQO1), kelch-like ECH-associated protein 1 (Keap1), IκB kinase (IKK), and arylhydrocarbon receptor (AhR)], and DNA. The evidence strongly suggests that the numerous mechanisms of quinone modulations (i.e., alkylation versus oxidative stress) can be correlated with the known pathology/cytoprotection of the parent compound(s) that is best described by an inverse U-shaped dose-response curve.
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Affiliation(s)
- Judy L Bolton
- Department of Medicinal Chemistry and Pharmacognosy (M/C 781), College of Pharmacy, University of Illinois at Chicago , 833 S. Wood Street, Chicago, Illinois 60612-7231, United States
| | - Tareisha Dunlap
- Department of Medicinal Chemistry and Pharmacognosy (M/C 781), College of Pharmacy, University of Illinois at Chicago , 833 S. Wood Street, Chicago, Illinois 60612-7231, United States
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Mahajan MK, Uttamsingh V, Daniels JS, Gan LS, LeDuc BW, Williams DA. In vitro metabolism of oxymetazoline: evidence for bioactivation to a reactive metabolite. Drug Metab Dispos 2010; 39:693-702. [PMID: 21177487 DOI: 10.1124/dmd.110.036004] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Oxymetazoline (6-tert-butyl-3-(2-imidazolin-2-ylmethyl)-2,4-dimethylphenol) has been widely used as a nonprescription nasal vasoconstrictor for >40 years; however, its metabolic pathway has not been investigated. This study describes the in vitro metabolism of oxymetazoline in human, rat, and rabbit liver postmitochondrial supernatant fraction from homogenized tissue (S9) fractions and their microsomes supplemented with NADPH. The metabolites of oxymetazoline identified by liquid chromatography (LC)/UV/tandem mass spectrometry (MS/MS), included M1 (monohydroxylation of the t-butyl group), M2 (oxidative dehydrogenation of the imidazoline to an imidazole moiety), M3 (monohydroxylation of M2), M4 (dihydroxylation of oxymetazoline), and M5 (dihydroxylation of M2). Screening with nine human expressed cytochromes P450 (P450s) identified CYP2C19 as the single P450 isoform catalyzing the formation of M1, M2, and M3. Glutathione conjugates of oxymetazoline (M6) and M2 (M7) were identified in the liver S9 fractions, indicating the capability of oxymetazoline to undergo bioactivation to reactive intermediate species. M6 and M7 were not detected in those liver S9 incubations without NADPH. Cysteine conjugates (M8 and M9) derived from glutathione conjugates and hydroxylated glutathione conjugates (M10 and M11) were also identified. The reactive intermediate of oxymetazoline was trapped with glutathione and N-acetyl cysteine and identified by LC/MS/MS. M6 was isolated and identified by one-dimensional or two-dimensional NMR as the glutathione conjugate of a p-quinone methide. We have shown the tendency of oxymetazoline to form p-quinone methide species via a bioactivation mechanism involving a CYP2C19-catalyzed two-electron oxidation. Nevertheless, we conclude that the formation of this reactive species might not be a safety concern for oxymetazoline nasal products because of the typical low-dose and brief dosage regimen limited to nasal delivery.
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Affiliation(s)
- Mukesh K Mahajan
- Department of Pharmaceutical Sciences, Massachusetts College of Pharmacy and Health Sciences, Boston, Massachusetts, USA.
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Ge X, Wakim B, Sem DS. Chemical proteomics-based drug design: target and antitarget fishing with a catechol-rhodanine privileged scaffold for NAD(P)(H) binding proteins. J Med Chem 2008; 51:4571-80. [PMID: 18616236 DOI: 10.1021/jm8002284] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Drugs typically exert their desired and undesired biological effects by virtue of binding interactions with protein target(s) and antitarget(s), respectively. Strategies are therefore needed to efficiently manipulate and monitor cross-target binding profiles (e.g., imatinib and isoniazid) as an integrated part of the drug design process. Herein we present such a strategy, which reverses the target --> lead rational drug design paradigm. Enabling this approach is a catechol-rhodanine privileged scaffold for dehydrogenases, which is easily tuned for affinity and specificity toward desired targets. This scaffold crosses bacterial (E. coli) cell walls, and proteome-wide studies demonstrate it does indeed bind to and identify NAD(P)(H)-binding proteins that are potential drug targets in Mycobacterium tuberculosis and antitargets (or targets) in human liver. This approach to drug discovery addresses key difficulties earlier in the process by only pursuing targets for which a chemical lead and optimization strategy are available, to permit rapid tuning of target/antitarget binding profiles.
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Affiliation(s)
- Xia Ge
- Department of Chemistry, Chemical Proteomics Facility at Marquette, Marquette University, PO Box 1881, Milwaukee, Wisconsin 53201, USA
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Molecular modeling and spectroscopic studies on the binding of guaiacol to human serum albumin. J Photochem Photobiol A Chem 2006. [DOI: 10.1016/j.jphotochem.2006.02.004] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Li Y, Yang X, van Breemen RB, Bolton JL. Characterization of two new variants of human catechol O-methyltransferase in vitro. Cancer Lett 2005; 230:81-9. [PMID: 16253764 DOI: 10.1016/j.canlet.2004.12.022] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2004] [Revised: 12/13/2004] [Accepted: 12/18/2004] [Indexed: 10/25/2022]
Abstract
Catechol O-methyltransferase (COMT) plays an important role in the inactivation of biologically active and toxic catechols. It has been shown that human soluble COMT (S-COMT) is genetically polymorphic with a wild type and at least one variant in which a valine has been substituted with a methionine at codon 108. This polymorphism has been the subject of intense molecular epidemiological studies because of the important role of COMT in the metabolism of catecholamines and catechol estrogens. Several epidemiological studies have shown that women, homozygous with the Val108Met variant, have an increased risk of developing estrogen-associated cancers. However, some other studies have shown that this COMT polymorphism is not associated with increased risk of developing cancers. These conflicting data suggest that additional COMT genetic variants might contribute to the increased risk of developing cancers. Although two new single nucleotide polymorphisms (SNP) that cause amino acid substitutions Ala22Ser and Ala52Thr have been identified recently, they have not been fully characterized. In the present study, Ala22Ser and Ala52Thr variants of human S-COMT were produced using recombinant DNA techniques, and then COMT properties were measured including enzymatic activity, thermostability, and sensitivity to inhibition mediated by 4-hydroxyequilenin (4-OHEN). The Ala22Ser variant showed lower methylation capacity and higher thermolability. In addition, this variant is sensitive to 4-OHEN mediated irreversible inhibition. Our data indicate that the Ala22Ser polymorphism might also be of functional significance and might play a role in susceptibility to estrogen-associated cancers.
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Affiliation(s)
- Yan Li
- Department of Medicinal Chemistry and Pharmacognosy (M/C 781), College of Pharmacy, University of Illinois at Chicago, 833 S. Wood St., Chicago, IL 60612-7231, USA
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Nematollahi D, Tammari E. Electrooxidation of 4-methylcatechol in the presence of barbituric acid derivatives. Electrochim Acta 2005. [DOI: 10.1016/j.electacta.2005.01.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Li Y, Yang X, Chang M, Yager JD, van Breemen RB, Bolton JL. Functional and structural comparisons of cysteine residues in the Val108 wild type and Met108 variant of human soluble catechol O-methyltransferase. Chem Biol Interact 2005; 152:151-63. [PMID: 15840388 DOI: 10.1016/j.cbi.2005.03.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2005] [Revised: 03/04/2005] [Accepted: 03/05/2005] [Indexed: 11/22/2022]
Abstract
Catechol O-methyltransferase (COMT) plays an important role in the inactivation of biologically active and toxic catechols. This enzyme is genetically polymorphic with a wild type and a variant form. Numerous epidemiological studies have shown that the variant form is associated with an increased risk of developing estrogen-associated cancers and a wide spectrum of mental disorders. There are seven cysteine residues in human S-COMT, all of which exist as free thiols and are susceptible to electrophilic attack and/or oxidative damage leading to enzyme inactivation. Here, the seven cysteine residues were systematically replaced by alanine residues by means of site-directed mutagenesis. The native forms and cysteine/alanine mutants were assayed for enzymatic activity, thermal stability, methylation regioselectivity, and reactivity of cysteine residues to thiol reagent. Our data showed that although there is only one encoding base difference between these two COMT forms, this difference might induce structural changes in the local area surrounding some cysteine residues, which might further contribute to the different roles they might play in enzymatic activity, and to the different susceptibility to enzyme inactivation.
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Affiliation(s)
- Yan Li
- Department of Medicinal Chemistry and Pharmacognosy (M/C 781), College of Pharmacy, University of Illinois at Chicago, 833 South Wood St., Chicago, IL 60612-7231, USA
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Kim JW, Ryu KE, Jang HS, Ahn WS, Choi JO, Chun HJ. Cytotoxic Effect of Urushiol-ethanol Micro-particles on Human Cervical Carcinoma Cells. JOURNAL OF PHARMACEUTICAL INVESTIGATION 2004. [DOI: 10.4333/kps.2004.34.1.023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Foti MC, Johnson ER, Vinqvist MR, Wright JS, Barclay LRC, Ingold KU. Naphthalene diols: a new class of antioxidants intramolecular hydrogen bonding in catechols, naphthalene diols, and their aryloxyl radicals. J Org Chem 2002; 67:5190-6. [PMID: 12126405 DOI: 10.1021/jo020184v] [Citation(s) in RCA: 132] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
1,8-Naphthalenediol, 5, and its 4-methoxy derivative, 6, were found to be potent H-atom transfer (HAT) compounds on the basis of their rate constants for H-atom transfer to the 2,2-di(4-t-octylphenyl)-1-picrylhydrazyl radical (DOPPH*), k(ArOH/DOPPH)*, or as antioxidants during inhibited styrene autoxidation, k(ArOH/ROO)*, initiated with AIBN. The rate constants showed that 5 and 6 are more active HAT compounds than the ortho-diols, catechol, 1, 2,3-naphthalenediol, 2, and 3,5-di-tert-butylcatechol, 3. Compound 6 has almost twice the antioxidant activity, k(ArOH/ROO)* = 6.0 x 10(6) M(-)(1) s(-1), of that of the vitamin E model compound, 2,2,5,7,8-pentamethyl-6-chromanol, 4. Calculations of the O-H bond dissociation enthalpies compared to those of phenols, (deltaBDEs), of 1-6 predict a HAT order of reactivity of 2 < 1 < 3 approximately 4 < 5 < 6 in general agreement with kinetic results. Calculations on the diols show that intramolecular H-bonding stabilizes the radicals formed on H-atom transfer more than it does the parent diols, and this effect contributes to the increased HAT activity of 5 and 6 compared to the activities of the catechols. For example, the increased stabilization due to the intramolecular H-bond of 5 radical over 5 parent of 8.6 kcal/mol was about double that of 2 radical over 2 parent of 4.6 kcal/mol. Linear free energy plots of log k(ArOH/DOPPH)* and log k(ArOH/ROO)* versus deltaBDEs for compounds 1-6 along with available literature values for nonsterically hindered monophenols placed the compounds on common scales. The derived Evans-Polanyi constants from the plots for the two reactions, alpha(DOPPH)* = 0.48 > alpha(ROO)* = 0.32, gave the expected order, since the ROO* reaction is more exothermic than the DOPPH* reaction. Compound 6 is sufficiently reactive to react directly with oxygen, and it lies off the log k(ArOH/ROO)* versus deltaBDE plot.
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Affiliation(s)
- Mario C Foti
- Department of Chemistry, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario, K1S 5B6 Canada
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Grace SC, Yamasaki H, Pryor WA. Spin stabilizing approach to radical characterization of phenylpropanoid antioxidants: an ESR study of chlorogenic acid oxidation in the horseradish peroxidase, tyrosinase, and ferrylmyoglobin protein radical systems. BASIC LIFE SCIENCES 2000; 66:435-50. [PMID: 10800455 DOI: 10.1007/978-1-4615-4139-4_23] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Affiliation(s)
- S C Grace
- Biodynamics Institute, Louisiana State University, Baton Rouge 70803-1800, USA
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