TUMOR PROMOTER-LIKE ACTIVITY OF THE MOLLUSCICIDAL LATEX OF CROWN-OF-THORNS (EUPHORBIA-MILII VAR HISLOPII) IN THE V79 COOPERATION ASSAY

The latex of 'Crown-of-Thorns' (Euphorbia miliivar. hislopii, syn. E. splendens) has been shown to be a potent plant molluscicide that could be used against the snails which are intermediate hosts of Schistosom a trematodes. However, a comprehensive toxicological evaluation of the latex is necessary before its large-scale use in schistosomiasis cont rol becomes possible. In fact, one cause for concern is the presence o f tumor-promoting phorbol esters in several plants of the Euphorbiacea e family. Phorbol esters as well as a number of other known tumor prom oters share the common property of inhibiting metabolic cooperation (i .e., exchange of low molecular weight molecules via gap junctions) bet ween Chinese hamster V79 cells in monolayer cultures. The present stud y was undertaken to determine if latex of E. milli presents tumor prom oter-like activity in this shortterm in vitro assay. Samples of lyophi lized E. milii latex were tested at a noncytotoxic concentration range (1, 10, 50 and 100 mu g/ml) in three independent experiments. 12-O-Te tradecanoylphorbol-13-acetate (10 ng/ml) was used as positive control. In all three assays, E. milli latex consistently inhibited metabolic cooperation between V79 cells at concentrations greater than or equal to 10 mu g/ml. These results indicate that E. milli latex contains tum or-promoting substances. These findings suggest that the use of crude latex as a molluscicide may pose a carcinogenic hazard to people who a re continuously exposed to the product.