Antidiabetics, antioxidant, enzyme inhibitory activity and polyphenolic profile of polyphenol rich extracts from three underutilized and indigenous vegetables (UIVs) from Nigeria

Background: Dietary diversity is one of the major ways to end hidden hunger and micronutrient deficiencies in developing countries i.e. Nigeria. This work was to evaluate and assess the nutritional advantage of underutilized and indigenous vegetables (UIVs) that grows in Dutsin-Ma metropolis in the Northern part of Nigeria, to emphasize the importance of dietary diversity for rural populace. This was achieved by documenting the polyphenolic profile, antioxidant, antidiabetes and enzyme inhibitory activity of polyphenolic rich extracts of three UIVs i.e. Cyphostemma adenocaule, Anchomanes difformis, Ampelocissus Africana. Results: The leaves of Anchomanes difformis possessed the highest total polyphenolic content (mg GAEs/g extract) 26.34 +/- 0.50, total flavonoid content (mg GAEs/g extract) 49.13 +/- 0.51 and total iridoid content (mg AUCs/g extract) 23.86 +/- 0.18 in that order. The various antioxidant assays (in vitro) employed, the polyphenolic extract of A. difformis displayed the most significant ability in terms of DPPH radical scavenging (mu g 43.64 +/- 0.94 mg GAEs/g extract), H2O2 reducing power (64.28 +/- 0.90 mg GAEs/g extract) and in ABTS radical cation assay (mg TEs/g extract) 98.79 +/- 1.95. These extracts displayed insignificant enzymatic inhibition on AChE (mg GALAEs/g extract) 1.77 +/- 0.07-2.29 +/- 0.04; alpha-amylase (mmol ACEs/g extract) 0.56 +/- 0.01- 0.60 +/- 0.01. Whereas, the polyphenolic extract of A. difformis displayed an average effective inhibition towards alpha-glucosidase (mmol ACEs/g extract) 3.66 +/- 0.02-22.81 +/- 0.01. Conclusion: The study shows that these UIVs may be contemplated as a new springboard for antidiabetics, antioxidant and enzyme inhibitory compounds in diets and food formulated products. The study further reiterates that neglected plant food and vegetables have immersed benefits to nutrition and health. (C) 2020 The Authors. Published by Elsevier B.V. on behalf of African Institute of Mathematical Sciences / Next Einstein Initiative.