Isoflavone C-glycosides isolated from the root of kudzu (Pueraria lobata) and their estrogenic activities

摘要

The chemical structures of six isoflavones (1-6) isolated from the kudzu root (Pueraria lobata) were elu-cidated on the basis of the NMR and MS analyses to be four isoflavone C-glycosides as 6"-O-α-D-glucopyr-anosylpuerarin (1), puerarin (2), 3'-methoxypuerarin (3), 6"-0-α-D-apiofranosylpuerarin (4), and two aglycons as biochanin A (5) and formononetin (6), respectively. The estrogenic activities of isolated com-pounds and related isoflavones were evaluated using a yeast two-hybrid assay. Genistein exhibited the highest activity among the evaluated compounds at 10-(-6) M followed by daidzein (10-(-5) M), baiochanin A (5) (lO-(-5) M), daidzin (10-(-5) M), 3',4',7-trihydroxyisoflavone (10-(-3) M), and formononetin (6) (10-(-2) M). The isoflavone C-glycosides (1-4) and 4',7-dimethoxyisoflavone showed no activities. In these results, it was found that the addition of 8-C-glucose or 3'-hydroxyl group to daidzein skeleton, or the substitu-tion of hydroxyl functions to methoxyl groups, decreased the estrogenic activity of daidzein, on the other hand, the addition of 7-O-glucose moiety had no influence on the activity.