title: In vitro inhibition of cytochrome P-450 reductases from pig liver microsomes by garlic extracts.
abstract: The activity of microsomal NADPH-cytochrome-P-450-reductase and NADH-cytochrome-b5-reductase are inhibited after the addition of an aqueous extract of a pharmaceutical preparation of garlic (Allium sativum, L.) to buffer-suspended microsomes. Incubation of garlic extract with isolated pig liver microsomes also decreases the activity of cytochrome P-450-dependent ethoxycoumarin deethylation. As measured by malondialdehyde release, the effects on the enzyme system are evidently not due to lipid peroxidation. No loss of cytochrome P-450 pigment is observed. Moreover, it could be shown that addition of garlic extract displays no protective effect on microsomal lipids when oxidation occurs spontaneously or is enforced by short-wave UV-irradiation. The above findings were reproduced after applying a HPLC-purified preparation of alliin to the incubation mixtures, suggesting that alliin is the active principle for the inhibitory effects observed in vitro.
authors.affiliation: Abteilung Biophysik, Fachbereich 1, Universität Bremen, Fed. Rep. of Germany.
authors.forename: B
authors.initials: B
authors.lastname: Oelkers
authors.forename: H
authors.initials: H
authors.lastname: Diehl
authors.forename: H
authors.initials: H
authors.lastname: Liebig
mesh_terms: D000818:Animals; D002851:Chromatography, High Pressure Liquid; D003579:Cytochrome Reductases / Q000037:antagonists & inhibitors / Q000378:metabolism; D042966:Cytochrome-B(5) Reductase; D005260:Female; D005737:Garlic; D066298:In Vitro Techniques; D015227:Lipid Peroxidation / Q000187:drug effects; D008297:Male; D008862:Microsomes, Liver / Q000187:drug effects / Q000201:enzymology*; D009245:NADH Dehydrogenase / Q000037:antagonists & inhibitors; D009251:NADPH-Ferrihemoprotein Reductase / Q000037:antagonists & inhibitors*; D010936:Plant Extracts / Q000494:pharmacology; D010946:Plants, Medicinal; D013552:Swine
chemical_list: D010936:Plant Extracts; D003579:Cytochrome Reductases; D042966:Cytochrome-B(5) Reductase; D009251:NADPH-Ferrihemoprotein Reductase; D009245:NADH Dehydrogenase