Acute and Sub-Acute Toxicity of Ethanolic Leaf Extracts of Rumex abyssinica Jacq. (Polygonaceae) and Mentha spicata L. (Lamiaceae)

Abstract

Rumex abyssinica Jacq. (Polygonaceae) is locally used in management of allergies and female reproductive healthcare; whereas Mentha spicata L. (Lamiaceae) is used to treat gastrointestinal and respiratory distress, dandruff, halitosis and malaria in Uganda. Owing to the paucity of data on their safety profiles, this study evaluated the acute and sub-acute toxicities of 70% ethanolic leaf extracts of both plants in mice and Wistar albino rats. The oral acute toxicity of both plants was evaluated in Swiss mice of 7 - 8 weeks old (16 - 22 g) body weight and LD50 determined. Sub-acute toxicity was evaluated in Wistar albino rats (6 per group) at dose rates of 500, 1000 and 1500 mg/kg for 28 days. The LD50 of R. abyssinica and M. spicata in mice was 7727 mg/kg and 13,606 mg/kg body weight, respectively. General signs of toxicity due to large doses of both plants extract included hyperurination, abdominal muscle twitches and convulsions. In the sub-acute toxicity test, rats treated with both extracts did not exhibit any clinical signs of toxicity; no mortality and changes in body weight were observed. R. abyssinica did not cause significant changes in haematological indices, except a significant increase in HCT (p < 0.05). However, a dose dependant significant decrease in HCT (p < 0.05) and a significant increase (p < 0.05) in the levels of WBC, LMY and MCHC were observed in rats treated with M. spicata extract. Biochemical test showed that both extracts caused a significant dose dependent increase (p < 0.05) in levels of ALT and ALP. Marked increase in the levels of AST was also observed in rats treated with M. spicata extract. Of the two extracts, only rats treated with R. abyssinica revealed congestion, hemorrhages and cellular infiltration in vital organs. In conclusion, the LD50 values of both plant extracts were above 5000 mg/kg suggesting that they are experimentally safe, thus justifying their use in traditional medicine. However, prolonged exposure to higher doses may cause observable alterations in histopathological, biochemical, and haematological parameters, particularly with R. abyssinica.