Assessment of Median Lethal Dose and Target Organ Toxicity of Oral Sub-chronic Administration of Newbouldia laevis in Mice and Rat Model of Toxicity

The acute and sub-chronic toxicities of the leaf extract of Newbouldia laevis, an ethnomedicinal herb use in the management of diabetes mellitus was investigated. For the acute toxicity study, 10 – 5000 mg/kg of the extract were administered orally to mice and obvious signs of toxic symptoms and mortality monitored for 24 h post extract administration. In the sub-chronic study, 302 and 604 mg/kg of the extract were orally administered daily for 90 days. Body weight changes as well as haematological and biochemical parameters were determined periodically. Qualitative phytochemistry was also conducted. Presence of flavonoids, saponins, tannins, reducing sugar, steroids, terpenoids, alkaloids and glycosides phytocompounds in the extract were detected. The oral LD50 was estimated to be above 5,000 mg/kg in mice. Ninety days oral administration of ethanol extract of N. laevis produced a significant (P<0.05) reduction in body weight at 604 mg/kg on the 31st day and at both 302 and 604 mg/kg on the 61st and 91st days compared to 5% Tween 20 vehicle control group. For liver function enzymes, the extract at both doses (302 and 604 mg/kg) produced significant (P<0.05) reduction in serum ALT enzyme activity at the 91st day with non-significant reduction in other liver function enzymes compared to vehicle control group. Non-significant changes were also recorded for haematological and kidney function markers. The results from this study provide evidence for safety profile of the ethanol leaves extract of N. laevis thus supportive of its validity in the use for treatment of chronic diseases like diabetes.