Chemical investigations for secondary metabolites from bioactive extract of uvaria accuminata from misali island, Pemba

Biological screening of organic materials obtained from coastal plants collected from Misali island, Pemba showed dichloromethane extract from stem bark of Uvaria accuminata to be active against drug resistant strains, D6 of Plasmodium falciparum. Chemical components of this extract were separated using several chromatographic techniques, including open column chromatography, flash chromatography, gel filtration and the thin layer chromatography (TLC). Normal and reverse phase silica as well as sephadex was used as stationary phases in separation and purification of compounds. Advanced purification of some of the isolated compounds was afforded by recrystallization procedures. A total of three compounds were obtained. These included a known special flavone, dasytrichone, (5-hydroxy-6,8,8-trimethyl-2-phenylchromene-4,7-dione) and two new compounds which were found to be 5-methoxyderivatives of dasytrichone and a novel flavone named acuminavone, which is consisted of dasytrichone fused to a three membered ring sesquiterpene bearing an exomethylene moiety. Although dasytrichone has previously been isolated from plants belonging to the Annonaceae family, this is the first time to be obtained from Uvaria species. Chemical structures of all metabolites were identified on the basis of their ID- and 2D-NMR spectral data such as 1H- and 13C-NMR, COSY, HSQC, HMBC ROESY and both low and high resolution MS information. X-Ray analysis was also used in elucidation of chemical structures of some of the isolated compounds.