Antimalarial compounds from Goniothalamus tenuifolius

Abstract

In the search for antimalarial compounds from Goniothalamus tenuifolius, four aristolactam alkaloids, namely aristolactam BI, aristolactam BII, velutinam and aristolactam AII were isolated along with a 4, 5-dioxoaporphine alkaloid named norcepharadione B, and an ethyl ester of 2, 4-dihydroxy-6-methylbenzoic acid. The structure identifications of all of the isolated compounds, including their unequivocal 13C NMR assignments, were achieved by analysis of their UV, IR, MS and NMR data. All compounds were evaluated for their antimalarial activity against Plasmodium falciparum T9/94 by radioisotope microdilution technique. The ethyl ester of 2, 4-dihydroxy-6-methylbenzoic acid, aristolactam BI, aristolactam BII, velutinam, norcepharadione B and aristolactam AII showed EC50 values of 33, 10.5, 11, 7.5, 7.5 and 9.5 mug/ml, respectively, whereas those of chloroquine and pyrimethamine were 0.03 and 2.8 mug/ml, respectively. This investigation is the first report of antimalarial activity of aristolactam alkaloids.