Planta Med. 2003 Apr; 69(4): 350-5.

New antimicrobial alkaloids from the roots of Polyalthia longifolia var. pendula.

Faizi S, Khan RA, Azher S, Khan SA, Tauseef S, Ahmad A.

H.E.J. Research Institute of Chemistry, International Center for Chemical Sciences, University of Karachi, Karachi, Pakistan. shaheen@khi.comsats.net.pk

Bioassay-guided isolation studies on the root extract of Polyalthia longifolia var. pendula possessing significant antibacterial activity led to the isolation of three new alkaloids pendulamine A (1), pendulamine B (2) and penduline (3) along with stigmasterol 3-O-beta-D-glucoside, allantoin, the known diterpenoid kolavenic acid, and the azafluorene alkaloid isoursuline. The structures of these compounds have been elucidated with the help of spectroscopic studies including 2D NMR experiments. Compounds 1 and 2, which are the only protoberberine alkaloids having a monosubstituted A ring with a hydroxy group at C-3, were found to be the active antibacterial principles of the roots. Their MIC values ranged between 0.02-20 microg against the tested bacteria.