Acute and sub-chronic oral toxicity studies on the methanol leaf extract of Gnetum africanum Welw in wistar rats.

Abstract

Aim: Acute and sub-chronic toxicity studies were performed on Gnetum africanum Welw leaves using well established guidelines and methods. In spite of its use as a herbal remedy, there is dearth of data on toxicity studies of the plant extract. Methods: Gnetum africanum leaves were identified by a plant taxonomist, air-dried, pulverized and extracted with 80 % methanol for 48 hours in July, 2015. The extract was concentrated in-vacuo and stored as Gnetum africanum extract (GAE) at 4oC. Thirty five male albino rats randomly divided into 7 groups (n=5) were used for acute toxicity test which was done in August, 2015. Rats in groups 1-6 were given GAE at 500, 1000, 2000, 3000, 4000 and 5000 mg/kg, respectively while group 7 rats received 10 ml/kg distilled water. Feed and water were provided and they were observed for signs of toxicity for 48 h. A 90-day sub-chronic toxicity study was conducted using 56 rats of 4 groups (n=14) in December 2015-March, 2016. Group 1 received feed without GAE, while groups 2-4 were given feed with GAE at 10, 20 and 40 mg/kg respectively. Four rats from each group were bled on days 30, 60 and 90 for clinical biochemistry and sacrificed for histopathological examination. Results: LD50 was greater than 5000 mg/kg while no-observed-adverse-effect-level was 40 mg/kg. Serum marker enzymes and creatinine were not increased in rats given extract in feed while there were no histopathological lesions in the organs studied. Conclusions: The extract is safe at both acute and sub-chronic levels.