Neuroprotective Limonoids of Root Bark of Dictamnus dasycarpus

A methanolic extract of Dictamnus dasycarpus root bark afforded four new degraded limonoids, 9alpha-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), 9beta-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 microM.