Neuroprotective limonoids of root bark of Dictamnus dasycarpus

A methanolic extract of Dictamnus dasycarpus root bark afforded four new degraded limonoids, 9 alpha-hydroxyfraxinellone-9-O-beta-D-glucoside (1), dictamnusine (2), dictamdiol A (3), and dictamdiol B (4), together with eight known compounds, dictamdiol (5), fraxinellone (6), fraxinellonone (7), 9 beta-hydroxyfraxinellone (8), calodendrolide (9), obacunone (10), limonin (11), and rutaevin (12). Compounds, 2, 3, 6, 9, 10, and 11 showed significant neuroprotective activity against glutamate-induced neurotoxicity in primary cultures of rat cortical cells at a concentration of 0.1 mu M.