| The chloroform extract of the leaves of Muntingia calabura L. (Elaeocarpaceae) exhibited a demonstrable cytotoxic activity when evaluated against the P-388 lymphocytic leukemia cell system in vitro. Bioactivity-directed fractionation of this extract led to the isolation of a cytotoxic compound, ;Bioassay-directed chromatographic fractionation of the cytotoxic chloroform extract of the stems of M. calabura afforded one compound, galangin-3,7-dimethyl ether, as an active constituent. However, this isolate was cytotoxic only for P-388 cells in vitro, among the systems in which it was tested. This rare flavonol, which was originally isolated as a natural product from a fern, is now reported for the first time as a constituent of a higher plant. From an 1-butanol-soluble extract of M. calabura stems, kaempferol-7-;Fractionation of the ethyl acetate of M. calabura leaves resulted in the isolation of three known flavonols, kaempferol, quercetin, and tiliroside. While the first two of the compounds were significantly active against P-388 cells, tiliroside was found to be noncytotoxic in all the cancer cell lines tested. Unambiguous NMR data were determined for tiliroside, using a combination of one- and two-dimensional NMR techniques. |
