Acute and Sub-chronic (28-day) Oral Toxicity Studies of Hydroalcohol Leaf Extract of Ageratum conyzoides L (Asteraceae)

Purpose: Ageratum conyzoides is an annual herbaceous plant commonly used in African traditional medicine as a purgative, antipyretic, anti-ulcer and wound dressing agent. The objective of this study was to investigate the acute and sub-chronic toxicity of A. conyzoides leaves in Wistar rats. Methods: In the acute test, the limit test dose of 5000 mg/kg was administered to Wistar rats and then observed individually 1 h post-dosing, and at least once daily for 14 days. Sub-chronic toxicity was evaluated after administering daily oral doses of 500 and 1000 mg/kg body wt., for 28 days to the rats, Biochemical and haematological assessments as well as body and relative organ weights of the rats were carried out Results: The limit dose of 5000 mg/kg did not cause any mortality or signs of acute toxicity in the rats tested during the observation period. In the sub-chronic tests, the results did not show any treatment– related abnormalities in terms of haematological and biochemical parameters. However, urea was significantly (p < 0.05) lower in the group treated with 500 mg/kg of A. conyzoides extract. The weekly body and organ weight of the rats showed no significant differences between the control and the rats treated with the extract except for liver where there was a significant increase (p < 0.05) in rats that received 1000 mg/kg, i.e., 3 ± 0.2 g as against 2.5 ± 0.1 g for the control. Conclusion: Our results suggest that the hydroalcohol extract of A. conyzoides is relatively safe when administered orally in rats.