Neuroprotective constituents from Hedyotis diffusa

In a bioassay-guided search for neuroprotective compounds from medicinal plants, a MeOH extract of whole plants of Hedoytis diffusa yielded five flavonol glycosides, kaempferol 3-O-[2-O-(6-O-E-feruloyl)-beta -D-glucopyranosyl] -beta -D-galactopyranoside (1), quercetin 3-O-[2-O-(6-O-E-feruloyl)-beta -D-glucopyranosyl]P-D-galactopyranoside (2), quercetin 3-O-[2-O-(6-O-E-feruloyl)-beta -D-glucopyranoside (3), kaempferol 3-O-(2-O-beta -D-glucopyranosyl)-beta -D-galactopyranoside (4), and quercetin 3-O-(2-O-beta -D-glucopyranosyl)-beta -D-galactopyranoside (5), and four O-acylated iridoid glycosides (6-9). Compounds 1 and 2 are previously unreported natural products, and all nine compounds exhibited significant neuroprotective activity in primary cultures of rat cortical cells damaged by L-glutamate.