ANTIPROLIFERATIVE EFFECT OF DEHYDRODIDEMNIN-B (DDB), A DEPSIPEPTIDE ISOLATED FROM MEDITERRANEAN TUNICATES

The biological effects of dehydrodidemnin B (DDB), a novel depsipeptid e isolated from Aplidium albicans, were studied on Ehrlich carcinoma g rowing in vivo and in primary cultures, and compared with those report ed for Didemnin B (DB). Daily administration of DB or DDB (2.5 mu g/mo use) almost duplicated the animal life-span and total number of tumour cells decreased by 70-90%. Results suggest a major effect of DDB when administered in the lag phase of growth. DDB behaved as a very potent inhibitor of protein synthesis; consequently, ornithine decarboxylase activity (ODC, EC 4.1.1.17) is drastically reduced by the DDB-treatme nt.