Evaluation of Toxicity of Strychnos henningsii (Gilg) (Loganiaceae) Leaves and Root Aqueous Extracts in Mice

Aim: Strychnos henningsii (Gilg) (Loganiaceae) has been used for treatment of various health conditions such as gastrointestinal complications, rheumatism and snake bites. However, the safety of extracts from S. henningsii has not been evaluated. This study was therefore carried out to evaluate the in vivo toxicity of S. henningsii leaves and root extracts with the view of determining if their use poses health risk.

Methodology: Acute and sub-acute toxicity was conducted in accordance with OECD guidelines. Swiss white mice were randomly selected and divided into 24 groups (n = 6) for acute (single administration) and sub-acute toxicity (28 days administration) studies. The mice were fasted overnight and graded doses of the aqueous extracts were orally administered to the tested groups at a dosage ranging from 75 to 2500 mg/kg. The control groups were orally administered with plain water. Clinical signs, mortality, fasting glucose levels, alanine transaminases, blood urea nitrogen and haemoglobin were evaluated. At the end of study, organs were harvested and processed for histopathology.

Results: In all the groups, there were no mortalities. The clinical signs which were noted in mice administered with extracts ranging from 750 mg/kg and above included: dullness, raised skin fur, staggering, reduction in locomotion and in food consumption, and mucoid stool. There were no significant (P>0.05) changes in body weight and the levels of fasting glucose, haemoglobin, blood urea nitrogen and alanine transaminases in the studied mice. Histopathology evaluation of organs of mice from sub-acute toxicity study administered dosages from 750 mg/kg showed mucoid enteritis and exfoliation. The loss of hepatolobular arrangement, periportal infiltration with inflammatory exudate in the liver and congestion of renal blood vessels was observed at a dosage of 2,500 mg/kg of root extract.

Conclusion: The study showed no mortality up to dose of 2,500 mg/kg. In addition sub-acute administration of dosages up to 750 mg/kg had no effect on the biochemical and hematological parameters. However, at histopathology dosages above 750 mg/kg bwt showed intestinal, hepatic and renal pathological alterations. The study recommends that the plant extracts may be safe at dosages below 750 mg/kg bwt.