Antioxidant Activity of the Isoflavonoids from the Roots of Maackia amurensis
Seven isoflavonoids, including a new glycoside, (6a R,11a R)-medicarpin-3- O-gentiobioside (6), were isolated from the roots of Maackia amurensis using repeated column chromatography on a Toyopearl HW-50F sorbent and identified by HPLC–PDA–MS, 1H NMR, 13C, 1H–1H COSY, HSQC NMR and HMBC NMR analyses as daidzin (1), genistein-7- O-gentiobioside (2), pseudobaptigenin-7- O-gentiobioside (3), formononetin-7- O-gentiobioside (4), (6a R,11a R)-maackiain-3- O-gentiobioside (5), and 5- O-methylgenistein-7- O-gentiobioside (7). In the model of oxidative stress induced by formalin injection, the isolated isoflavone and pterocarpan glucosides 1-7 were shown to reduce the formation of malondialdehyde (MDA) and other thiobarbituric acid reactive substances (TBARS), as well as glutathione peroxidase (GPO) activity in rats.