Search

Diphyllin isolated from Haplophyllum bucharicum Litv. (Rutaceae), an endemic plant of Uzbekistan, displayed a moderate antiproliferative activity towards human monocytes (IC50 = 35.2 microM) and Leishmania promastigotes (IC50 = 14.4 microM), by a mechanism of action that involved interaction with macromolecules and resulted in cell cycle arrest in the S-phase and inhibition of protein synthesis. In the intracellular amastigote form of the parasite, diphyllin exerted a strong specific inhibitory activity (IC50 = 0.2 microM) resulting from the inhibition of parasite internalization within macrophages. This property was mainly due to modulation of macrophage phagocytosis and, to a lesser extent, it also involved interference with surface molecules of the promastigote membrane.

Some quassinoids (1-6) isolated previously as plant growth inhibitors from the leaves of Eurycoma longifolia Jack. (Simaroubaceae) were subjected to in vitro tests on anti-tumor promoting, antischistosomal and plasmodicidal activities. The most active compound for inhibition of tumor promoter-induced Epstein-Barr virus activation (anti-tumor promotion) was 14,15beta-dihydroxyklaineanone (5, IC(50) = 5 microM). Longilactone (1) gave significant antischistosomal effect at a concentration of 200 microg/ml. 11-Dehydroklaineanone (3) and 15beta-O-acetyl-14-hydroxyklaineanone (6) showed potent plasmodicidal activity (IC(50) = 2 microg/ml). Thus it was suggested that E. longifolia possesses high medicinal values due to the occurrence of a variety of quassinoids., (Copyright 2002 Elsevier Science Ireland Ltd.)