New Isoflavone and Triterpene Glycosides from Soybeans

Chemical investigation of a soybean phytochemical concentrate resulted in the isolation and identification of two new isoflavanones, dihydrodaidzin (1) and dihydrogenistin (2), a new isoflavone, 2‘ ‘,6‘ ‘-O-diacetyloninin (3), and two new triterpenoid saponins (13 and 14). Nine known isoflavonoids (4−12) and three known saponins (15−17) were also identified. Structures of the new compounds were established by a combination of extensive NMR (DEPT, DQF-COSY, HMBC, HMQC, and ROESY) studies and chemical degradation. Cytotoxic activities (ED50) of various extracts and selected isoflavonoids and saponins were measured against human stomach carcinoma (Hs 740.T, Hs 756 T), breast adenocarcinoma (Hs 578 T, Hs 742.T), and prostate carcinoma (DU 145, LNCaP-FGC) cell lines. Isoflavonoids 3 and 5 were more active than 1 and 2 versus at least one of the three cell lines examined, indicating the importance of the 2,3-double bond in cytotoxicity. Saponins 13, 14, and 15 were slightly more active than saponins 16 and 17, indicating that sugar attachments at position-22 enhance cytotoxic activity.