Inhibition of 17β-estradiol activation by CYP1A1: Genotype- and regioselective inhibition by St. John's Wort and several natural polyphenols

• Published in: Biochimica et biophysica acta 2011, Vol.1814 (1), p.168-174
• Main Authors: Schwarz, Dieter, Kisselev, Pyotr, Schunck, Wolf-Hagen, Roots, Ivar
• Format: Article
• Language: English
• Subjects: Amino Acid Substitution; Anti-Inflammatory Agents, Non-Steroidal - pharmacology; Biocatalysis - drug effects; CYP1A1; Cytochrome P-450 CYP1A1 - genetics; Cytochrome P-450 CYP1A1 - metabolism; Dose-Response Relationship, Drug; Estradiol; Estradiol - chemistry; Estradiol - metabolism; Flavonoids - pharmacology; Flavonols - pharmacology; Genotype; Humans; Hydroxylation - drug effects; Hypericum - chemistry; Hypericum perforatum; Inhibition; Metabolic activation; Perylene - analogs & derivatives; Perylene - pharmacology; Phenols - pharmacology; Plant Extracts - pharmacology; Polymorphism; Polyphenols; Quercetin - pharmacology; Recombinant Proteins - metabolism; Stereoisomerism; Stilbenes - pharmacology; Substrate Specificity
• ISSN: 1570-9639; 0006-3002; 1878-1454
• DOI: 10.1016/j.bbapap.2010.09.014

Several epidemiological studies associate certain CYP1A1 genotypes, alone or in combination, with an increased risk of estrogen-related cancers. Previously we demonstrated that metabolic activation of estrogens by CYP1A1 is a genotype-dependent reaction with the CYP1A1.2 (Ile462Val) variant being the most efficient catalyst (Kisselev et al.). To answer the question whether genotype-dependent inhibition of activation of estrogens by CYP1A1 could also contribute, we studied the inhibition of hydroxylation activity of the most common allelic variants of human CYP1A1 towards 17β-estradiol. We expressed and purified CYP1A1.1 (wild-type), CYP1A1.2 (Ile462Val), and CYP1A1.4 (Thr461Asn) and performed inhibition assays by natural polyphenols of our diet and drugs of NADPH-dependent estradiol hydroxylation in reconstituted CYP1A1 systems. From the polyphenols studied, a St. John's Wort ( Hypericum perforatum) extract, some of its main single constituents hypericin, pseudohypericin, and quercetin, as well as the flavonols kaempferol, myricetin and the phytoestrogens resveratrol and tetramethyl-stilbene exhibited strong inhibition. For the St. John's Wort extract and its single constituents hypericin, pseudohypericin, and quercetin, inhibition exhibited a remarkable dependency on the CYP1A1 genotype. Whereas (wild-type) CYP1A1.1 was most inhibited by the whole crude extract, the variant CYP1A1.2 (Ile462Val) was significantly stronger inhibited by the constituents in its pure form: IC 50 values for 2-hydroxylation was more than two times lower compared with the wild-type enzyme and the variant CYP1A1.4 (Thr461Asn). Besides this, the inhibition exhibited a remarkable regioselectivity. The data suggest that risk of estrogen-mediated diseases might be not only influenced by CYP1A1 genotype-dependent activation but also its inhibition by natural polyphenols of our diet and drugs. ► Inhibition of activation of estrogens by CYP1A1 is genotype-dependent. ► A St. John´s Wort extract and single constituents of it exhibited genotype-dependent inhibition. ► The CYP1A1.1 variant (wild type) was mostly inhibited by the crude extract. ► The CYP1A1.2 variant (Ile463Val) was mostly inhibited by single constituents of St. John's Wort extract.