Abstract
Phytochemical investigation of the ethyl acetate extract of the stem of Dendrosicyos socotrana Balf. f. resulted in the isolation of a new pentacyclic cucurbitane glycoside Socotroside, in addition to the three known cucurbitacins, dihydrocucurbitacin D, dihydrocucurbitacin F and cucurbitacin G. The structures of the isolated compounds were established on the basis of their spectral data. The isolated cucurbitacin aglycones showed marked cytotoxic activity.