Phenolic content and antioxidant capacity of selected underutilized fruits grown in Sri Lanka

The present study was carried out to evaluate the total phenolic content and antioxidant properties of four selected underutilized fruits species: Manilkara hexandra (Roxb.) Dubard (Palu), Salacia chinensis L. (Himbutu), Schleichera oleosa (Lour.) Oken (Koan) and Eugenia uniflora (Cherry) grown in Sri Lanka. Antioxidative constituents were extracted into water and the antioxidant activity of fruit extracts was assessed using biochemical assays: 1,1-diphenyl-2(2,4,6-trinitrophenyl) hydrazine (DPPH) radical scavenging assay (n=3) and ferric reducing power assay (FRAP)(n=3). The total phenolic content was estimated using Folin-Ciocalteu’s colorimetric assay and expressed as milligrams of gallic acid equivalents per 100 g of both fresh and dry weight of fruit. The fruit extracts tested exhibited a broad range of antioxidant activity as measured by DPPH radical scavenging and FRAP assays. The highest antioxidant activity was exhibited by Manilkara hexandra (Palu) in both assays performed. Furthermore, it was observed that the antioxidant activity as measured by the DPPH radical scavenging activity and FRAP assay strongly correlated (R² = 0.997) with total phenol content for extracts of all four underutilized fruit species tested. Therefore, the antioxidant activity of the fruits could be attributed to phenolic compounds present in the samples. This is the first time that antioxidant potential of some of the above fruits is reported.