Liquid chromatography-electrospray ionization mass spectrometry study of the flavonoids of the roots of Astragalus mongholicus and A-membranaceus

High-performance liquid chromatography-electrospray ionization mass spectrometry has been applied to analyze the flavonoids of Huangqi, the roots of Astagalus mongholicus and A. membranaceus. Eight flavonoids were identified as calycosin-7-O-beta-D-glucoside, calycosin-7-O-beta-D-glucoside-6 -O-malonate (2), ononin, (6aR, 11aR)-3-hydroxy-9,10-dimethoxypterocarpan-3-O-beta-D-glucoside, calycosin, (3R)-7,2'-dihydroxy-3',4'-dimethoxyisoflavan-7-O-beta-D-glucoside formononetin-7-O-beta-D-glucoside-6 -O-malonate and formononetin by direct comparison with the isolated standards from Huangqi. The existence of (6aR,11aR)-3-hydroxy-9,10-dimethoxypterocarpan (3R)-7,2'-dihydroxy-3',4'-dimethoxyisoflavan, astrapterocarpanglucoside-6'-O-malonate and astraisoflavanglucoside-6'-O-malonate was detected. This is the first report of flavonoid glycoside malonates in these two Astragalus species, and malonate 2 is a structurally completely identified new compound. (C) 2000 Elsevier Science BN. All rights reserved.