Measurement of antioxidant synergy between phenolic bioactives in traditional food combinations (legume/non-legume/fruit) of (semi) arid regions: insights into the development of sustainable functional foods

Abstract

Numerous under-researched edible plants are present in the desert regions of the world. These plants could be potential candidates to ensure food security and provide valuable bioactive compounds through diet. In general, the bioactives present in food manifest synergistic, additive, or antagonistic interactions. The current study investigates such interactions between food combinations traditionally consumed in (semi) arid regions. Five edible plants (representing three food categories) were selected: Prosopis cineraria and Acacia senegal (legume), Capparis decidua and Cordia dichotoma (non-legume), and Mangifera indica (fruit), in which the first four are largely underutilized. The antioxidant capacities of individual plant extracts and their binary mixtures were analyzed by DPPH free radical scavenging and FRAP assays. The total phenolic content (TPC) and total flavonoid content (TFC) were also determined. The highest antioxidant activity was obtained for Prosopis cineraria extract (EC50—1.24 ± 0.02 mg/ml, FRAP value—380.58 ± 11.17 μM/g), while Mangifera indica exhibited the lowest antioxidant activity (EC50—2.54 ± 0.05 mg/ml, FRAP value—48.91 ± 4.34 μM/g). Binary mixture of Prosopis cineraria (legume) and Mangifera indica (fruit) manifested maximum synergy (experimental EC50—0.89 ± 0.01 mg/ml, theoretical EC50—3.79 ± 0.05 mg/ml). Correlation studies [Pearson’s correlation coefficient (r) and Principal component analysis (PCA)] showed a high correlation of TFC with DPPH and TPC with FRAP values. LC–MS analysis of methanolic plant extracts detected 43 phenolic compounds (including phenolic acids, flavonoids, and isoflavonoids), possibly responsible for the observed food synergy. For edible plants of the (semi) arid zones, this study is a first-of-its-kind and provides scientific validation to the traditional wisdom of consuming these foods together. Such indigenous food combinations derived from desert flora could offer valuable insights into development of sustainable functional foods and nutraceuticals.