Estrogenic activities of Ginkgo biloba extracts.
Ginkgo biloba extracts (GBE) are extracted from the leaves of Ginkgo biloba tree. GBE contains 24% of phytoestrogens, which is kaempferol, quercetin, and isorhamnetin. It has been reported that phytoestrogens could be a part of SERMs (Selective estrogen receptor modulators) and possibly the alternative HRT (Hormone replacement therapy) for postmenopausal women. The goal of this study was to investigate the potencies of GBE and its major components (quercetin, kaempferol, isorhamnetin) for estrogenic effect, which confirms the capacity as an alternative HRP. It was found that GBE and its major components exerted a dual action on ER-alpha and ER-beta in competitive binding assay. The binding affinity of these chemicals to ER-beta was higher than to ER-alpha. In the E-screen assay, these chemicals induced cell proliferation in ER-positive MCF-7 cell, but not in ER-negative MDA-MB-231 cells. The cell proliferation induced by these chemicals was blocked by tamoxifen. Also, GBE and its major components induced pS2 and PR (progesterone receptor) transcription in MCF-7 cells. Therefore these results indicated that GBE and its major components had the weak estrogenic activities through the estrogen response pathway by an interaction with the ER. In conclusion, we provided the evidence of potential estrogenic activities of GBE, which could be useful as an alternative HRP. However, further studies are required to assess the physiological significance of GBE in animals and humans.
Oh
Seung-Min
SM
College of Pharmacy, Sungkyunkwan University, 300, Chunchun-dong, Jangan-Ku, Suwon, Kyunggido 440-746, South Korea.
Chung
Kyu-Hyuck
KH
D001667:Binding, Competitive / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D004965:Estrogen Antagonists / Q000494:pharmacology; D047628:Estrogen Receptor alpha; D047629:Estrogen Receptor beta; D004968:Estrogens, Non-Steroidal; D005260:Female; D044948:Flavonols / Q000494:pharmacology; D015870:Gene Expression / Q000187:drug effects; D020441:Ginkgo biloba; D006801:Humans; D044949:Kaempferols / Q000494:pharmacology; D008565:Membrane Proteins / Q000235:genetics; D010936:Plant Extracts / Q000494:pharmacology; D053766:Presenilin-2; D011794:Quercetin / Q000494:pharmacology / Q000031:analogs & derivatives; D012333:RNA, Messenger / Q000096:biosynthesis; D011960:Receptors, Estrogen / Q000187:drug effects; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013629:Tamoxifen / Q000494:pharmacology
D004965:Estrogen Antagonists; D047628:Estrogen Receptor alpha; D047629:Estrogen Receptor beta; D004968:Estrogens, Non-Steroidal; D044948:Flavonols; D044949:Kaempferols; D008565:Membrane Proteins; C508861:PSEN2 protein, human; D010936:Plant Extracts; D053766:Presenilin-2; D012333:RNA, Messenger; D011960:Receptors, Estrogen; C047368:3-methylquercetin; D013629:Tamoxifen; C006552:kaempferol; D011794:Quercetin