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

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.

METHODS: In the acute toxicity test, aqueous extract of Stigma madyis was orally adminis- tered 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,&nbsp; the extract caused an observable significant increase&nbsp;&nbsp; (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.

CONCLUSIONS: 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 &ge; 1000 mg/kg could be hepatotoxic. Therefore, only lower doses should be encouraged for therapeutic use.