Acute and sub-chronic oral GLP toxicity of Withania somnifera root extract in Sprague Dawley rats.

Objectives: Withania somnifera (WS) is a valuable medicinal plant that has been used against several ailments. The medicinal properties of WS are ascribed to existence of secondary metabolites which are in great demand in herbal nutraceutical industry. Despite well-known therapeutic effects of WS, it is necessary to assess preclinical toxicity of WS plant on rats and further explore its potential application against treatment of various disorders in humans. The existing study assessed oral acute and sub-chronic toxicities of WS root extract in Sprague Dawley (SD) rats (male and female) for 14 and 90 days, respectively under OECD-423 and -408 guidelines as well as GLP compliance.

Methods: In acute toxicity, rats of either sex were orally fed a dose of 2,000 mg/kg. In sub-chronic toxicity, animals were orally administered repeated doses of WS root extract at 250, 500, 1,000 mg/kg for 90 days with an additional 14-day recovery period. Two more groups (n=5 animals each) receiving vehicle and 1,000 mg/kg of WS root extract for 90 days were also observed.

Results: In acute toxicity, the results revealed that LD₅₀ of WS root extract in SD rats was higher than 2,000 mg/kg. In sub-chronic toxicity, oral administration of extract for 90 days showed no significant toxicological changes in rats. Haematological and serum chemistry markers were found within normal range. Terminal necropsy showed no gross or histopathological outcomes.

Conclusions: The no-observed-adverse-effect level (NOAEL) of WS root extract was 1,000 mg/kg body weight, and safe to use at this dose in rats.