Phenolic compounds characterisation and antioxidant activity of black plum (Vitex doniana) fruit pulp and peel from Côte d’Ivoire

Abstract

This study was conducted to first determine the phenolic compounds and then the antioxidant activity of black plum fruit pulp and peel. For these characterisations, classic methods were used. Moreover, the ability of extracts to scavenge free radicals and their reducing power were measured according to 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP) methods, respectively. The total polyphenol, flavonoid and anthocyanin contents of pulp and peel ranged from 202.51 ± 4.19 to 463.45 ± 6.85 mg gallic acid equivalent (GAE)/100 g of Dry Weight (DW), 75.71 ± 1.03 to 145.55 ± 1.03 mg quercetin equivalent (QE)/100 g DW, and from 1.91 ± 0.08 to 8.28 ± 0.83 mg cyanidin 3-O-β-D-glucoside equivalent (C3GE)/100 g DW respectively. However, these compounds were higher in peel extracts than in pulp extracts. In addition, peel extract showed the strongest antioxidant capacities. Significant correlations were found between methods applied to determine antioxidant activity (DPPH and FRAP) in black plum pulp and peel extracts and their total phenols and flavonoids contents. Cinnamic acid and gallic acid were mains phenols in pulp and peel extracts respectively, except fruits peel from Ferke where the main phenol was cinnamic acid. Thus, peel of black plum fruit could be used as an inexpensive and natural source of antioxidants and contribute to the prevention of degenerative diseases.