Structural Elucidation and Antiplasmodial Activities of Some Compounds Isolated from The Rhizome of Cochlospermum Tinctorium

Abstract

Cochlospernum tinctorium A. Rich was investigated for its chemical constituents and its antiplasmodial activities. The chemical constituents of petroleum ether, dichloromethane and ethyl acetate extracts of the rhizome of the plant were successively studied. The in vitro antiplasmodial activities for petroleum ether, dichloromethane, ethyl acetate, ethanol and water extracts as well as the isolated compounds were determined. Three compounds isolated from the dichloromethane extract have been identified by spectroscopic methods to be triacontanol, triacontanyl p-coumarate and triacontanyl ferulate. This is the first report of the isolation of the two esters and the long chain saturated alcohol from the plant. Another compound was obtained from the dichloromethane extract and coded D9. The petroleum ether extract of the rhizome yielded stigmasterol and two compounds which were coded PE6 and PE11. The ethyl acetate extract of the rhizome yielded two compounds which were coded E13 and E166 Using an in vitro technique, the inhibition of growth of Plasmodium falciparum (chloroquine sensitive, 3D7 and chloroquine resistance DD2, strains,) were investigated based on the principle of uptake of 3H-hypoxanthine by viable parasites on various extracts of Cochlospermum tinctorium and also on the isolated compounds with chloroquine as standard. The percentage inhibition for all the extracts and isolated compounds were found to be dose-dependant, with the aqueous and dichloromethane extracts being more active with IC50 values 32.27 (ig/ml and 24.34 |J.g/ml for the chloroqiune sensitive and 30.90 jig/ml and 23.45 |j.g/m! for the chloroquine resistant strains respectively.