Three new cardenolides (3, 9 and 10), along with eight known ones, were isolated from the latex of
Calotropis procera. The structural determination was accomplished by the 1D- and 2D-NMR spectra as
well as HRESIMS analysis. The growth inhibitory activity of the latex and its sub-fractions as well as
isolated compounds was evaluated against human A549 and Hela cell lines. The results exhibited that
latex had strong growth inhibitory activity with IC50s of (3.37 lM, A-549) and (6.45 lM, Hela). Among
the four extracts (hexane, chloroform, ethyl acetate and aqueous), chloroform extract displayed the
highest potential cytotoxic activity, with IC50s of (0.985 lM, A-549) and (1.471 lM, Hela). All the isolated
compounds displayed various degrees of cytotoxic activity and the highest activity was observed by
calactin (1) with IC50s values of (0.036 lM, A-549) and (0.083 lM, Hela). None of these isolated
compounds exhibited good antimicrobial activity evaluated by determination of their MICs using the
broth microdilution method against various infectious pathogens. The structure–activity relationships
for cytotoxic activity were also discussed.