A new flavonol glycoside and activity of compounds from the flower of Nymphaea candida.

A new compound, kaempferol 3-O-(2''-O-galloylrutinoside) (1), was isolated from the white flower of Nymphaea candida, together with nine known flavonol glycosides, kaempferol (2), kaempferol 3-O-beta-D-glucopyranoside (3), kaempferol 3-O-alpha-l-rhamnopyranoside (4), kaempferol 3-O-alpha-l-rhamnopyranosylglucopyranoside (5), kaempferol 7-O-beta-D-glucopyranoside 3-(O-alpha-l-rhamnopyranosylglucopyranoside) (6), quercetin (7), quercetin 3-O-beta-D-xylopyranoside (8), myricetin (9), myricetin 3'-O-beta-D-xylopyranoside (10). The structure of 1 was established on the basis of the analysis of its 1D and 2D NMR spectral data. Compounds 1-7 and 9 exhibited moderate to significant antioxidant activities, which were evaluated by measurement of low-density lipoprotein (LDL) and malondialdehyde (MDA) levels in vitro. Compounds 1, 3, 4, 6 and 9 exhibited promising neuroprotective effects on ischemic injury model of cultured rat cortical neurons treated with sodium dithionite in glucose-free medium. Furthermore, compounds 1, 5, and 9 had distinct cytotoxicity to adrenal gland pheochromocytoma, PC12 cells, being treated by the same way.