Inhibitory effects of flavonoids in ginkgo biloba extract on aromatase activity

Program: Abstracts - Orals, Featured Poster Presentations, and Posters
Session: SAT 292-325-Breast & Prostate Cancer
Saturday, June 15, 2013: 1:45 PM-3:45 PM
Expo Halls ABC (Moscone Center)

Poster Board SAT-316
Yong Joo Park*1, Min Sun Yi1, Kyu Hyuck Chung1 and Seung Min Oh2
1Sungkyunkwan University, Suwon, South Korea, 2Hoseo University, Asan, South Korea
Ginkgo biloba extracts (GBE) is the world most popular phytomedicines and has been used for cardiovascular, renal, respiratory, circulatory disease and especially, disorder of central nervous system. In previous studies, we found that GBE played as selective estrogen receptor modulator (SERM) and inhibited aromatase activity. We assumed that GBE was possible aromatase inhibitor and we analyzed it to define major active compounds causing its inhibitory effects. GBE contains 24% of flavonols (kaempferol, quercetin, isorhamnetin) and 6% terpene lactones (ginkgolide, bilobalide). In this study, we tested inhibitory effects on aromatase activity with three major flavonols (kaempferol, quercetin, isorhamnetin) using JEG-3 cells (human placenta cells) and recombinant protein (human plancenta microsome). In both systems, kaempferol showed the strongest inhibition effects among three flavonols. 50 mM of kaempferol inhibited 95% aromatase activity in JEG-3 cells (IC50: 38.0 mM) and 31% aromatase activity in recombinant protein (IC50: 87.7 mM). 50 mM of isorhamnetin (29% in JEG-3 cells, 11% in recombinant protein) and 50 mM of quercetin (37% in JEG-3 cells, 15% in recombinant protein) also showed aromatase inhibitory effects, however, we concluded that kaempferol is a main active inhibitor among the GBE components. The inhibited aromatase activity was accompanied by decreasing CYP19 mRNA expression, and transcriptional suppression. They were revealed by real-time PCR using CYP19 CDS primer and CYP19 reporter gene assay with CYP19 1a promoter. The present study showed that kaempferol is a main component causing aromatase inhibitory effects in GBE and it works with CYP19 mRNA decreasing and transcriptional suppression.

Nothing to Disclose: YJP, MSY, KHC, SMO

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Sources of Research Support: National Research Foundation of Korea funded by238 the Korean government (MEST)