Evaluation of the safety of oral intake of aqueous extract of Stigma maydis (corn silk) in rats

Abstract

Background. Corn silk (Stigma madyis) is used in ethnomedicine for the management of diabetes, kidney stones, depression, fatigue, urinary infections and as a slimming tea. However, there is limited literature on its effect on body weight, lipid, hematological, hepatocellular, nephrological and histopathological indices which the present study evaluated. Materials and methods. In the acute toxicity test, aqueous extract of Stigma madyis was orally administered to rats using a gavage, in doses of up to 5 g/kg body weight. The rats were observed for any behavioral changes, signs of toxicity or mortality. In the sub-acute toxicity, rats were orally administered 500, 1000 and 2000 mg/kg Stigma madyis extract for 28 days. On the 29th day, the rats were euthanized and the following parameters measured; lipid profile, hematology, serum chemistry and histopathology of the liver and kidney. Results. In the acute toxicity test, Stigma madyis did not cause any mortality and was non-toxic at the dose of up to 5 g/kg body weight. In the sub-acute study, the extract caused an observable significant increase (p<0.05) in triglycerides (TAG), low density lipoprotein (LDL) and very low density lipoprotein (VLDL), while the concentration of high density lipoprotein (HDL) decreased significantly (p<0.05) when compared to the control group. AST and ALT increased significantly (p<0.05) in rats treated with 1000 and 2000 mg/kg of Stigma maydis compared to their control. The histopathological results revealed degenerative changes in the liver at 2000 mg/kg body weight extract. Conclusion. In long term treatment, toxic effects were observed in liver at the doses of 1000 and 2000 mg/kg. This study suggests that prolonged use of higher doses of aqueous extract of Stigma maydis ≥1000 mg/kg could be hepatotoxic. Therefore, only lower doses should be encouraged for therapeutic use.