Phytochemical Studies on Alstonia scholaris.

Reinvestigation of the flowers of Alstonia scholaris of Pakistan origin have resulted in the isolation of three new triterpenoids, two of the ursane type, 3β -acetate-24-nor-urs-4,12-diene ester triterpene (1) and 3β -hydroxy-24-nor-urs-4,12,28-triene triterpene (2), and one of the oleanane type, 3,28-β - diacetoxy-5-olea-triterpene (3), together with two known triterpenes,α-amyrin acetate (4) and ursolic acid (5). This is the first report of the isolation of 4 and 5 from the flower part of this species. The structures of 1 - 5 were elucidated with the aid of extensive NMR-spectroscopic studies.