Lack of antidiabetic activity of the methanol extract of Costus spicatus in rats

Resumo

Costus spicatus (Costaceae), popularly known as "cana-do-brejo" in folk medicine is used as a diuretic, for urinary tract infections and as antidiabetic agent. The aim of the present work was to evaluate the antidiabetic activity potential of the methanol extract os Costus spicatus (MECS) in rats. The antihyperglycemic effect was evaluated in normoglycemic male Wistar rats (150-200 g). These animals were divided into five groups of five animals each and were treated orally with saline solution (0.9%), metformin 500 mg/kg (reference drug) or MECS at the doses of 100, 200, and 400 mg/kg. After treatments, animals received orally glucose (3g/Kg) and their blood glucose levels were measured during 120 min. The average blood glucose before treatment was 82 ± 2 mg/dL. Metformin was able to inhibit significantly the hyperglycemia after glucose administration. However, these effects were not observed with MECS. In order to evaluate the hypoglycemic activity MECS was tested in alloxan-induced diabetic rats. These animals showed average fasting blood glucose of 453 ± 14 mg/dL. Metformin was able to reduce 51 ± 11% glucose levels in diabetic rats, however, MECS not showed significantly effect. In conclusion, these results suggest that methanol extract obtained from Costus spicatus leaves not presents antidiabetic activity, at least in the experimental model tested in this study. Other experiments are required to confirm these results.