Studies on the antitumor effect of cucurbitacins.

The carcinostatic activity of elatericin A, elatericin B, elaterin, elaterin methylether, dihydroelatericin A, and tetrahydroelatericin A, all cucurbitacins of a triterpene structure, and of trans-4-hydroxy-4-methylpent-~-enoic acid, the isolated side chain of the cucurbitacin molecule, was studied. Three cucurbitacins, elatericin A, elatericin B, and elaterin produced a moderate inhibition of growth of Sarcoma 180, Sarcoma Black, and Ehrlich ascites carcinoma. Sarcoma 180 proved to be the most sensitive tumor. Morphological changes of Ehrlich ascites cells, consisting of blistering and thread formation without swelling or vacuolization, were obtained by incubation with low concentrations of elatericin A, elatericin B, elaterin methylether, and elaterin. Comparatively higher concentrations of cucurbitacins were needed to affect the tumor-producing capacity of these cells after in vitro incubation and to depress the rate of respiration measured by Warburg manometry.