STUDY OF THE EMBRYOFETO-TOXICITY OF CROWN-OF-THORNS (EUPHORBIA-MILII)LATEX, A NATURAL MOLLUSCICIDE

The crude latex of Crown-of-Thorns (Euphorbia milli var. hislopii) is a potent plant molluscicide and a promising alternative to the synthet ic molluscicides used in schistosomiasis control. The present study wa s undertaken to investigate the embryofeto-toxic potential of E. milii latex. The study is part of a comprehensive safety evaluation of this plant molluscicide. Lyophilized latex (0, 125, 250 and 500 mg/kg body weight) in corn oil was given by gavage to Wistar rats (N = 100) from days 6 to 15 of pregnancy and cesarean sections were performed on day 21 of pregnancy. The numbers of implantation sites, living and dead f etuses, resorptions and corpora lutea were recorded. Fetuses were weig hed, examined for external malformations, and fixed for visceral exami nation, or cleared and stained with Alizarin red S for skeleton evalua tion. A reduction of body weight minus uterine weight at term indicate d that E. milii latex was maternally toxic over the dose range tested. No latex-induced embryolethality was noted at the lowest dose (125 mg /kg) but the resorption rate was markedly increased at 250 mg/kg (62.5 %) and 500 mg/kg (93.4%). A higher frequency of fetuses showing signs of delayed ossification (control: 17.4%; 125 mg/kg: 27.4% and 250 mg/k g: 62.8%; P<0.05 vs control) indicated that fetal growth was retarded at doses greater than or equal to 125 mg latex/kg body weight. No incr ease in the proportion of fetuses with skeletal anomalies was observed at the lowest dose but the incidence of minor skeletal malformations was higher at 250 mg/kg body weight (control: 13.7%; 125 mg/kg: 14.8%; 250 mg/kg: 45.7%; P<0.05 vs control). Since a higher frequency of min or malformations was noted only at very high doses of latex which are embryolethal and maternally toxic, it is reasonable to conclude that t his plant molluscicide poses no teratogenic hazard or, at least, that this possibility is of a considerably low order of magnitude.