Differential effects of IH636 grape seed proanthocyanidin extract and a DNA repair modulator 4-aminobenzamide on liver microsomal cytochrome 4502E1-dependent aniline hydroxylation.
Previous studies from our laboratories have linked the protective abilities of IH636 grape seed proanthocyanidin extract (GSPE) with inactivation of anti-apoptotic gene bcl-XL, and modification of several other critical molecular targets such as DNA-damage/DNA-repair, lipid peroxidation and intracellular Ca2+ homeostasis. Especially, GSPE provided dramatic protection against acetaminophen (APAP)-induced hepatotoxicity, significantly increased bcl-XL expression in the liver, and antagonized both necrotic and apoptotic deaths of liver cells in vivo. However, it was not clear from this study whether anti-apoptogenic and anti-necrotic effects of GSPE were: (i) due to its interference with endonuclease activity, (ii) due to its antioxidant effect, or, (iii) due to its ability to inhibit microsomal drug metabolizing enzyme(s), such as CYP-4502E1. Since CYP-4502E1 primarily metabolizes acetaminophen in mice and rats, this study specifically focused on CYP-4502E1's catalytic activity in vitro. Overall this investigation compared the in vitro aniline hydroxylation patterns of: (i) in vivo GSPE-exposed and unexposed (control) mouse liver microsomes, (ii) induced (1% acetone in drinking water for 3 days) and uninduced rat liver microsomes in the presence and absence of GSPE in vitro, and (iii) control rat liver microsomes in the presence of an anti-APAP agent 4-aminobenzamide (4-AB) in vitro. For the in vivo assessment, male B6C3F1 mice were fed GSPE diet (ADI 100 mg/kg body wt) for 4 weeks, and liver microsomes were isolated from both control and GSPE-fed mice for aniline hydroxylation, a specific marker of CYP-4502E1 activity. Data show that hydroxylation was 40% less in microsomes from GSPE-exposed livers compared to control microsomes. Similarly, when rat liver microsomes were incubated with various concentrations of GSPE in vitro (100 and 250 microg/ml), aniline hydroxylation was inhibited to various degrees (uninduced: 40 and 60% and induced: 25 and 50%, respectively with 100 and 250 microg/ml). Influence of GSPE on hydroxylation patterns were compared with another hepatoprotective agent 4-aminobenzamide (4-AB), a well-known modulator of nuclear enzyme poly(ADP-ribose) polymerase, and the data shows that 4-AB did not alter aniline hydroxylation at all. Collectively, these results may suggest that GSPE has the ability to inhibit CYP-4502E1, and this is an additional cytoprotective attribute, in conjunction with its novel antioxidant and/or antiendonucleolytic potential.
Ray
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Department of Pharmacology, Toxicology and Medicinal Chemistry, Arnold & Marie Schwartz College of Pharmacy and Health Sciences, Long Island University, Brooklyn, New York 11201, USA. sray@liu.edu
Parikh
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Hickey
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Bagchi
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Bagchi
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D010129:4-Aminobenzoic Acid / Q000494:pharmacology*; D000082:Acetaminophen / Q000494:pharmacology*; D000096:Acetone / Q000008:administration & dosage / Q000494:pharmacology; D000284:Administration, Oral; D000814:Aniline Compounds / Q000378:metabolism*; D000818:Animals; D001549:Benzamides; D001682:Biological Availability; D002384:Catalysis / Q000187:drug effects; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D019610:Cytoprotection / Q000187:drug effects*; D004260:DNA Repair; D004305:Dose-Response Relationship, Drug; D056604:Grape Seed Extract; D066298:In Vitro Techniques; D007527:Isoenzymes / Q000378:metabolism; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D008862:Microsomes, Liver / Q000187:drug effects*; D010936:Plant Extracts / Q000008:administration & dosage / Q000494:pharmacology*; D044945:Proanthocyanidins; D051381:Rats; D017207:Rats, Sprague-Dawley; D062366:para-Aminobenzoates
D000814:Aniline Compounds; D001549:Benzamides; D056604:Grape Seed Extract; C511402:Grape Seed Proanthocyanidins; D007527:Isoenzymes; D010936:Plant Extracts; D044945:Proanthocyanidins; D062366:para-Aminobenzoates; D000096:Acetone; D000082:Acetaminophen; C041338:4-aminobenzamide; D003577:Cytochrome P-450 Enzyme System; D010129:4-Aminobenzoic Acid