<i>In vitro</i> antioxidant, hypoglycemic and oral glucose tolerance test of banana peels

Abstract

Banana fruit is claimed to have antidiabetic effects despite its high calorie content, and its peels also contain vital phytoconstituents including gallocatechin. Previously banana pulp has been studied for antihyperglycemic effects, and in the present investigation antihyperglycemic effect of ethanolic extract of inner peels of Musa sapientum (EMS), Musa paradisiaca (EMP), Musa cavendish (EMC) and Musa acuminata (EMA) fruit was evaluated using oral glucose tolerance test in normoglycemic rats. In vitro antioxidant study was conducted using DPPH, H₂O₂ radical scavenging assay and ferric reducing power assay. Wistar rats were divided into fourteen groups and twelve groups received different doses of aforementioned extracts, while control group received gum acacia solution and remaining group received standard drug, glimepiride. All the rats received glucose load at a dose of 2 g/kg body weight. Groups treated with EMC and EMA showed significant decrease in glucose level (p< 0.01) at 150 min as compared to control group. In hypoglycemic study, only EMP 500 mg/kg, p.o. treated group revealed a significant decrease (p< 0.05) in glucose level at 120 min, while other groups did not show any sign of hypoglycemia. In glucose tolerance test, animals treated with EMC and EMA depicted dose dependent antihyperglycemic effect at 150 min while EMS and EMP showed significant reduction in plasma glucose at higher doses. In a similar fashion, EMA i.e. M. acuminata demonstrated highest antioxidant activity followed by EMC against DPPH radical. In ferric reducing power and H₂O₂ scavenging assay, EMA demonstrated maximal antioxidant activity when compared with other extracts.

Keywords:  In-vitro antioxidant; Musa sapientum; Musa paradisiaca; Musa cavendish; Musa acuminata; Oral glucose tolerance test