Phytochemical Composition, Antioxidant Activity, Biochemical Properties and Blood Glucose Lowering Potential of Unblanched and Blanched Wild Lettuce Leaf

Abstract

Wild lettuce, an underutilized leafy vegetable, contains essential nutrients and bioactive compounds to manage diseases. This study evaluated the phytochemical composition, antioxidant activity, biochemical properties and blood glucose lowering potential of unblanched and blanched wild lettuce leaf. Fresh wild lettuce leaves were processed into flours to obtain blanched (95±1^oC, 2 min.) (BF) and unblanched leaf flour (UBF) samples. The UBF and BF were respectively used to substitute 20, 30 and 40% of maize flour. The chemical composition, antioxidant activity and in vivo hypoglycaemic effects of the samples were evaluated. The crude protein and fibre contents of the UBF and BF ranged from 34.0-35.6 and 8.9-9.9 g/100g, respectively. The phosphorous (255.8-283.0 mg/100g) was the most abundant element in the blends. The Ca/P and Na/K molar ratios for the UBF and BF samples were 0.64-0.93 and 0.84-0.92, respectively. The concentrations of the phytochemicals in the BF were lower than those of the UBF, except for oxalate and flavonoid. The antioxidant activities of UBF were higher for the 2, 2-diphenyl-1-picryhydrazyl and ferric-reducing than those of the BF, but lower in iron chelating and nitric oxide radicals. The blood glucose reduction (%) potential of the UBF and the BF in Alloxan-induced diabetic rats were dose dependent, and the values varied from 46.4 - 82.7 and 28.8 - 83.4, respectively. Wild lettuce leaf flour contained bioactive compounds with antioxidant and blood glucose lowering potential. Hence, wild lettuce leaf may be suitable as an antidiabetic agent.

Keywords: Phytochemicals, antioxidant, hypoglycaemic, wild lettuce biochemical parameters.