Water and ethanol extracts of Piper nigrum in regulating thyroid function and lipid peroxidation in mice

An investigation was made to evaluate the effects of water and ethanol extracts of Piper nigrum L. fruits in the alteration of the serum thyroid hormone concentrations and tissue lipid peroxidation in liver, the main target organ of many drugs. The alcohol extract, at a dose of 4.0 mg/kg for 15 days, caused thyrotoxicosis as evidenced by increased concentrations of thyroxine and triiodothyronine. A concomitant increase in hepatic lipid peroxidation with a decrease in superoxide dismutase and/or catalase activities also indicated its peroxidative effect. However, a trial with the aqueous extract did not exhibit any toxic effect either on thyroid or in liver functions. Rather, the latter extract appeared to be antithyroidic and antiperoxidative in nature as it could decrease serum thyroid hormone concentrations and hepatic lipid peroxidation, respectively. It is suggested that the aqueous extract of Piper nigrum may be preferred over the alcohol extract for therapeutic uses.