Premium
Inhibition of Aromatase Activity by Tannins and Flavonoids from Sorghum bicolor
Author(s) -
Dowd Christopher,
Hargrove James,
Hartle Diane,
Greenspan Phillip
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.1_supplement.700.4
Subject(s) - tannin , chemistry , aromatase , sorghum , proanthocyanidin , bran , biochemistry , food science , enzyme , pharmacology , polyphenol , biology , medicine , antioxidant , agronomy , raw material , organic chemistry , cancer , breast cancer
Aromatase catalyzes the conversion of testosterone to estradiol and is a target for chemotherapy of breast and prostate cancers. We compared in vitro inhibition of human aromatase and porcine α‐amylase by bran extracts from two sorghum cultivars that have similar phenolic levels but differ in tannin content. Tannin‐rich sumac sorghum inhibited α‐amylase more strongly (IC 50 = 1.4 μg/mL) than did black sorghum (IC 50 = 11.4 μg/mL), which lacks tannins. Sumac inhibited aromatase activity slightly more than did black sorghum (IC 50 = 10.8 μg/mL v. 12.2 μg/mL). Bovine serum albumin (BSA), which binds tannins, reduced inhibition by sumac but not black sorghum in both enzymatic reactions. Sumac tannins, separated from other flavonoids on Sephadex LH‐20, inhibited both enzymes but showed reduced inhibition in the presence of BSA. Non‐tannin flavonoids from either cultivar had higher IC 50 values for both enzymes than the tannins, and BSA had little effect on their inhibition. We conclude that aromatase is inhibited both by non‐tannin flavonoids and by the tannins of sorghum. Only non‐tannin flavonoids are expected to be bioavailable to prostate or breast tissue. (Supported by USDA Grant # 5854304363)