Toxicity Study of Pittosporum ochrosiaefolium Bojer (Pittosporaceae) a Medicinal Plant of Madagascar

Abstract

The present work aimed to assess the leaf toxicity of Pittosporum ochrosiaefolium Bojer, a well-known medicinal plant endemic to Madagascar. Leaf methanolic extract (LME), obtained after successive extractions by hexan and methanol, was tested in vivo on warm and cold-blooded animals and in vitro on isolated atria of guinea-pig. LME was toxic to mice with a LD50 of about 46.69 mg/kg of body weight by intraperitoneal route. It induced mainly nervous disorders (body fasciculation, clonic convulsions), respiratory troubles (reduction of respiration frequency and cyanosis) and diarrheas. By intraperitoneal route, LME (46.69 mg/kg) caused histopathological lesions in lungs, liver, kidneys, small and large intestines but had no effects on brain, heart and stomach. Vascular congestion, inflammatory infiltrates, edema and necrosis were frequently observed. LME had a positive inotropic effect but no significant chronotropic one on isolated atria. It did not alter renal and hepatic functions at 21.24 mg/kg. It was highly toxic to the frog Ptychadena mascareniensis (LC50 of 13.51 µg/mL) and the fish Cyprinus carpio (LC50 of 8.2 µg/mL). It was also toxic to mosquito larvae Culex quinquefasciatus and Aedes albopictus with LC50 of 720 ppm and 910 ppm respectively. Different chemical compound groups were found in LME but only saponins proved to be toxic. Under certain conditions, P. ochrosiaefolium might be exploited as source of pesticides or therapeutic molecules.