Antioxidant Efficacy of Selected Underutilized Fruit Species Grown in Sri Lanka

The present study was carried out to determine the vitamin C content, total phenolic content (TPC), antioxidant efficacy and total monomeric anthocyanin content (TMAC) of twenty-one underutilized fruit species grown in Sri Lanka. Approximately 5g of fruit homogenates was used to determine the vitamin C content while lyophilized aqueous extracts were used to perform in-vitro antioxidant assays. Folin-Ciocalteu’s colorimetric assay was used to determine TPC. The 2,2-diphenyl-1-pycrylehydrazyl (DPPH) radical scavenging, 2,2’- azinobis- 3- ethylbenzothiazoline-6-sulphonic acid (ABTS) total antioxidant activity and ferric reducing antioxidant power (FRAP) assays were used to determine antioxidant efficacy of fruit extracts, while the pH differential method was used to determine TMAC. The highest TPC (104 mg of gallic acid equivalents/g on dry weight (DW) basis), reducing power (155μmol of ferrous sulphate equivalents/g DW), and the lowest IC₅₀ (0.0004 g of DW/mL) were recorded in Phyllanthus emblica and obtained the first rank in overall antioxidative properties among the tested fruit species. Fruits with the highest total antioxidant activity were Flacourtia indica, Morus alba, Phyllanthus emblica and Syzygium caryophyllatum. The highest TMAC was found in S. caryophyllatum (79 mg of cyanidin-3-glucoside (C3G)/g DW) and the lowest in Elaeocarpus. serratus (0.29 mg C3G/g DW). Results obtained in this study can be used as baseline data to carry out further research and formulation of food compositional tables. The underutilized fruit species tested could be used assources of natural antioxidants in nutraceuticals and in novel food product development.