IDENTIFICATION OF ISOFLAVONES IN THE ROOTS OF PUERARIA-LOBATA

The isoflavones of the roots of Pueraria lobata (Willd.) Ohwi (Puerari ae Radix) were investigated by high-performance liquid chromatography (HPLC) coupled to photodiode array (PDA) and to mass spectroscopy (MS) using atmospheric pressure chemical ionization (APCI) or electrospray ionization (ESI) in combination with collision-activated decompositio n (CAD) (HPLC-APCI-CAD-MS or ESI-CAD-MS) for identification of glycosi des and HPLC-APCI-CAD-MS for identification of aglycones. The major gl ycosides are derived from daidzein (9) and most are 8-C-glycosides. 3' -Hydroxypuerarin-4'-O-deoxyhexoside (2b) and 3'-methoxy-6 ''-O-D-xylos ylpuerarin (6) were identified as new constituents. MS data were obtai ned for puerarin-4'-O-D-glucoside (1), 3'-hydroxypuerarin (2a), puerar in (3), 3'-methoxypuerarin (4), 6 ''-O-D-xylosylpuerarin (5), daidzin (7) and 3'-methoxydaidzin (8), which were previously characterized by NMR analysis. Isoflavones identified in Puerariae Radix comprise 3'-me thoxydaidzein (10), genistein (12), daidzein-7-O-methyl ether (13a), 3 '-methoxydaidzein-7-O-methyl ether or 3'-methoxyformononetin (13b) and biochanin A (15), while previous characterization of daidzein (9) and formononetin (14) was substantiated by MS data. The structure of comp ound 11 could not be established by MS techniques. The estrogenic acti vity was mainly located in the aglycone fraction.