title: Effects of flavonoid phytochemicals on cortisol production and on activities of steroidogenic enzymes in human adrenocortical H295R cells.
abstract: Inhibitory effects of flavonoid phytochemicals, flavones, flavonols and isoflavones on cortisol production were examined in human adrenal H295R cells stimulated with di-buthylyl cAMP. In addition, the inhibitory effects of these chemicals on the activity of P450scc, 3beta-HSD type II (3beta-HSD II), P450c17, P450c21 and P45011beta, steroidogenic enzymes involved in cortisol biosynthesis, were examined in the same cells. Exposure to 12.5 microM of the flavonoids 6-hydroxyflavone, 4'-hydroxyflavone, apigenin, daidzein, genistein and formononetin significantly decreased cortisol production (by 6.3, 69.6, 47.5, 26.6, 13.8 and 11.3%, respectively), and biochanin A significantly decreased cortisol production (by 47.3%) at a concentration of 25 microM without any significant cytotoxic effects or changes in cell number. Daidzin, the 7-glucoside of daidzein, did not alter cortisol production by H295R cells at concentrations over 10 microg/ml (24 microM). Daidzein-induced reduction of cortisol production by H295R cells was not inhibited by the estrogen receptor antagonist ICI 182,780. The flavonoids 6-hydroxyflavone, daidzein, genistein, biochanin A and formononetin strongly and significantly inhibited microsomal 3beta-HSD II activity at concentrations from 1 to 25 microM, and I(50) values were estimated to be 1.3, 2, 1, 0.5 and 2.7 microM, respectively. In addition, these flavonoids significantly inhibited microsomal P450c21 activity at 12.5 and/or 25 microM. In addition, 6-hydroxyflavone inhibited activity of microsomal P450c17 and mitochondrial P45011beta at 12.5 and/or 25 microM. Results of Lineweaver-Burk's plot analysis indicate that daidzein is a competitive inhibitor of the activity of 3beta-HSD II and P450c21. K(m) and V(max) values of 3beta-HSD II for DHEA were estimated to be 6.6 microM and 328pmol/minmg protein, respectively. K(m) and V(max) values of P450c21 for progesterone were estimated to be 2.8 microM and 16pmol/minmg protein, respectively. K(i) values of 3beta-HSD II and P450c21 for daidzein were estimated to be 2.9 and 33.3 microM, respectively.
authors.affiliation: Department of Biochemistry, Faculty of Pharmaceutical Sciences, Hoshi University, 2-4-41 Ebara, Shinagawa-ku, Tokyo 142-8501, Japan.
authors.forename: Shuji
authors.initials: S
authors.lastname: Ohno
authors.forename: Satoshi
authors.initials: S
authors.lastname: Shinoda
authors.forename: Satoshi
authors.initials: S
authors.lastname: Toyoshima
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Nakazawa
authors.forename: Tsunehisa
authors.initials: T
authors.lastname: Makino
authors.forename: Shizuo
authors.initials: S
authors.lastname: Nakajin
mesh_terms: D015096:3-Hydroxysteroid Dehydrogenases / Q000037:antagonists & inhibitors / Q000378:metabolism; D000302:Adrenal Cortex / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology; D002460:Cell Line; D065607:Cytochrome P-450 Enzyme Inhibitors; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D004958:Estradiol / Q000031:analogs & derivatives* / Q000494:pharmacology; D020847:Estrogen Receptor Modulators / Q000494:pharmacology; D005419:Flavonoids / Q000494:pharmacology*; D000077267:Fulvestrant; D006801:Humans; D006854:Hydrocortisone / Q000096:biosynthesis*; D007529:Isoflavones / Q000494:pharmacology; D007700:Kinetics
chemical_list: D065607:Cytochrome P-450 Enzyme Inhibitors; D020847:Estrogen Receptor Modulators; D005419:Flavonoids; D007529:Isoflavones; D000077267:Fulvestrant; C013908:daidzin; D004958:Estradiol; D003577:Cytochrome P-450 Enzyme System; D015096:3-Hydroxysteroid Dehydrogenases; D006854:Hydrocortisone