Oppositinines A and B: New vasorelaxant β-carboline alkaloids from Neisosperma oppositifolia

Abstract

A phytochemical study on the bark of Neisosperma oppositifolia (Apocynaceae) yielded two new β-carboline indole alkaloids, oppositinines A (1) and B (2), together with five known alkaloids, isoreserpiline, isocarapanaubine, vobasine, 10-methoxydihydrocorynantheol-N-oxide, and ochropposinine oxindole. Structural elucidation of 1 and 2 was performed using 2D NMR methods. Oppositinines A (1) and B (2) showed potent vasorelaxant effects on the rat aorta. © 2010 Pharmaceutical Society of Japan.