Phytochemical and toxicological studies of leaf extracts of Gambeya boiviniana Pierre (Sapotaceae) a medicinal plant

A toxic activity was found in a leaf extract of Gambeya boiviniana (Chrysophyllum bovinianum), an endemic medicinal Sapotaceae of Madagascar. A purification process including a butanol fractionation and neutral lead acetate precipitation allowed to obtain a partially purified toxic extract (E2) from a clear, brick-red crude hydro-alcoholic extract (CE) with a bitter taste. The toxic principles were bitter, thermostable, soluble in water, in ethanol and in butanol. They were not precipitable by lead neutral acetate. They could be flavonons, unsaturated sterol, triterpenes or phenol compounds. Both CE and E2 were toxic to mice, in which E2 induced symptoms suggestive of central nervous system damage. The 24 h Lethal Dose 50% (LD50) was comprised between 118.15 mg/kg and 122.39 mg/kg of the mouse weight. It caused histological lesions characterized by vascular congestion and hemorrhage in various organs. CE and E2 caused an hemolytic activity on red cells of sheep. E2 was toxic in frog (Ptychadena mascareniensis) tadpoles, a dose effect was observed and Lethal Concentration 50% (LC50) was of 41.66 μg/ml. On fish (Gambusia holbrooki), at 9.2 mg/ml, the mortality rate was 0% but at 9.34 mg/ml it was 100%. E2 had no effect on mosquito (Culex quinquefasciatus) larvae.