New Flavonoid Glycosides from Pyrrosia petiolosa and their Neuroprotective Activities Against Glutamate-Induced Oxidative Stress in HT22 Hippocampal Cells

Pyrrosia petiolosa (Christ) Ching (Polypodiaceae) has been used for treating gonorrhea, asthma, hematuria, urolithiasis and diuresis in folk medicine. We investigated to isolate the active components from a methanolic extract of this species that showed neuroprotective activities against glutamate-induced oxidative stress in HT22 hippocampal cells. The extract of P. petiolosa was suspended in water and then fractionated with n-hexane, CHCl₃, EtOAc, and n-BuOH. Ten compounds were isolated from the BuOH fraction using various chromatographic techniques. The structures of six flavonol glycosides, three flavanone glycosides and one phenolic compound were identified as kaempferol 4'-O-[6'''-O-(3''-hydroxycinnamoyl)-β-D-glucopyranosyl(2→1)-β-D-glucopyranoside] (1), kaempferol 3-O-α-rhamnopyranosyl-7-O-α-arabinofuranoside (2), kaempferol 3-O-β-gluopyranosyl-7-O-apiofuranoside (3), astragalin (4), kaempferol 3,7-O-β-D-diglucopyranoside (5), huazhongilexone 7-O-β-D-glucopyranuronic acid (6), huazhongilexone 7-O-(methyl-β-D-glucopyranuronic acid) (7), naringenin 7-O-(methyl-β-D-glucopyranuronic acid) (8), gossypetin 7-O-β-D-glucopyranoside (9), and chlorogenic acid (10), respectively. Among them, compounds 1, 2, 3 and 6 are reported for the first time in nature, and compounds 7 and 8 are newly reported from P. petiolosa. The neuroprotective activities of the isolated compounds were evaluated in HT22 hippocampal cells [1]. Of the ten compounds, compounds 7 and 8 showed neuroprotective effect against glutamate induced-oxidative stress in HT22 cells. References: [1] Lee KY, Hwang L, et al. (2010) Biosci Biotechnol Biochem 74: 1704–1706.