A new antitumour substance, 7-oxabicyclo (2.2.1)-5-heptene-2,3-dicarboxylic anhydride.

7-Oxabicyclo(2.2.1)-5-heptene-2,3-dicarboxylic anhydride has been found to possess antitumour activity against Ehrlich ascites carcinoma cells. The tumour cells incubated with the drug showed a decrease in the viable counts and cell proliferation. These effects were confirmed by in vivo studies in Swiss albino mice. The compound has a direct cytotoxic effect on the tumour cells. Vacuolization and disruption of the cytoplasm accompanied by unequal nuclear division and scattered chromosomes were recorded. In addition, 250 and 10 mg/kg were found to be the MTD and MED respectively. A dose of 25 mg/kg injected i.p. for 5 consecutive days in the tumour-transplanted animals caused a significant increase in their survival period. The compound has been shown to have a significant inhibitory effect on the DNA and RNA biosynthesis of EAC cells after 3 hr of administration; the protein biosynthesis was less affected. Meanwhile, the cellular contents of these metabolites were significantly reduced.