Further Studies on the Antitumor Effect of Cucurbitacins

Incubation with elatericin A and B produced pronounced morphological alterations in Ehrlich ascites carcinoma, SBLl solid and SBLl ascites cells. Mouse spleen lymphocytes, chicken embryo fibroblasts, and human epithelial kidney cells showed similar changes when tenfold higher concentrations of cucurbitacins were applied. No morphological changes could be induced in rat leukocytes and in mouse erythrocytes. Intraperitoneal injection of elatericin A into Ehrlich ascites carcinoma-bearing mice produced morphological alterations in the carcinoma cells similar to those found in vitro. The reversible character of these alterations in vivo was demonstrated. In addition, morphological alterations, produced by elatericin A in Ehrlich ascites carcinoma cells in vitro, were reversed following their inoculation in vivo. The blistering of the tumor cells is considered to be a process of a pinocytotic rather than of a destructive type. Elaterin methylether (EME) was found to be the most active antitumor compound of the cucurbitacin derivatives studied. Absorption and excretion of the radioactive material following administration of EME-C¹⁴were rapid in normal mice and delayed in Ehrlich ascites carcinoma-bearing mice.