Glycemic Responses, Enzyme Activity, and Sub-Acute Toxicity Evaluation of Unripe Plantain Peel Extract in Rats

Plantain (Musa paradisiaca L.) is a tropical monocotyledonous, succulent plant of the Musaceae family commonly grown for food in the tropical regions of the African, Asian, and South American continents, where its parts are also sought for ethnomedicinal purposes in the treatment of burns, inflammation, and diabetes, among others. In the present preliminary exploratory study, the ethanol extract of the underutilized Musa paradisiaca peel (MPE) was evaluated for its in vitro inhibitory effects on α-amylase and α-glucosidase, as well as its in vivo hypoglycemic activity and potential biochemical toxicity. MPE (100, 200, 400 mg/kg) was orally administered to normal experimental rats for 30 days, following which the lipid profile, antioxidant status, and serum/tissue indices of hepatic, renal, and cardiac functions were evaluated. MPE produced significant inhibition (p < 0.05) of α-amylase (37%) and α-glucosidase (46%) at 120 µg/mL in vitro. The effect was lower than that of acarbose (IC50 = 44.4 ± 1.14 and 15.60 ± 0.01 µg/mL, respectively). A modest blood glucose-lowering effect of MPE was observed at the highest tested dose (400 mg/kg) following subacute oral administration. During this treatment period, no biochemical alterations of toxicological importance were caused by MPE, as the organ–body weight ratio and serum/tissue indicators of organ function/damage were not adversely altered. In conclusion, MPE demonstrated inhibitory activity against both α-amylase and α-glucosidase, which may contribute to its potential hypoglycemic effects. Additionally, the findings indicate that the peel extract is non-toxic in rats following sub-acute administration at doses up to 400 mg/kg body weight. Further studies involving diabetic models and chronic exposure will substantiate and extend these preliminary observations.