Antioxidant and Carbohydrate-Hydrolysing Enzymes Potential of Sechium edule (Jacq.) Swartz (Cucurbitaceae) Peel, Leaves and Pulp Fresh and Processed

Sechum edule peel, leaves and pulp were investigated for their chemical composition (total phenol, flavonoid, carotenoid and vitamin C content), and for antioxidant activity and carbohydrate-hydrolysing enzymes (alpha-amylase and alpha-glucosidase) inhibition. In order to evaluate the incidence of cooking process on retention of healthy phytochemicals, the pulp was subjected to different treatments (grill roasting, domestic oven baking, microwave cooking, blanching and steaming). Cooking processes reduced the total phenol content (58.5 mg/g extract for fresh pulp vs 26.3 and 29.3 mg/g extract for roasted and steamed samples, respectively). Pulp was found to be the most active in 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) (IC50 of 0.1 mg/mL), whereas peel showed the highest activity in 2,2-diphenyl-1-picrylhydrazyl (DPPH) test (IC50 of 0.4 mg/mL). Moreover, peel exhibited the highest inhibitory activity against alpha-amylase with an IC50 of 0.2 mg/mL, except for steamed cooking process, which drastically influenced the bioactivity against both enzymes.