Cytotoxic Cardenolides from the Leaves of Calotropis gigantea

Two 15beta-hydroxycardenolides (1,2) and a 16alpha-hydroxycalactinic acid methyl ester (3) along with eleven known compounds including 16alpha-hydroxycalotropagenin, coroglaucigenin, 16alpha-hydroxycalotropin, calactinic acid, calotoxin, 6'-O-(E-4-hydroxycinnamoyl)desglucouzarin, 12beta-hydroxycoroglaucigenin, frugoside, calotropagenin, 9,12,13-trihydroxyoctadeca-10(E),15(Z)-dienoic acid and R-(-)-mevalonolactone were isolated from the polar fraction of the CH(2)Cl(2) extract, and n-BuOH extract of the leaves of this plant. The isolated compounds were evaluated for their inhibitory activities against a panel of cell lines.