ANTIOXIDANT ACTIVITY AND CAPACITY OF SILVER NANOPARTICLES BIOSYNTHESIS OF COMMON FRUITS AQUEOUS EXTRACTS OF THE SUNDARBAN FOREST

Abstract

Fruits provide numerous health-promoting polyphenols and antioxidants. The Sundarbans mangrove forest of Bangladesh produces various fruits, and off them ten to twelve are known to be consumed or used as an ingredient in food preparations. These fruits were used in this study to evaluate the total polyphenols (TPH) contents following the method of Folin-Ciocalteu’s; and the antioxidant activity by measuring 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radicals scavenging, reducing power and total antioxidant capacity. Additionally, capacity of silver nanoparticles (AgNPs) biosynthesis of the fruits was determined spectrophotometrically. Sonneratia apetala fruit showed the highest TPH content (45.7 mg of gallic acid equivalent (GAE)/g powder). The fruit also showed the largest antioxidant activity attributed to the DPPH free radicals scavenging, reducing power, and total antioxidant capacity. Additionally, S. apetala fruit showed the highest capacity in the AgNPs biosynthesis (OD, 0.41; 10 mg powder/mL). Avicennia officinalis, Ceriops decandra, Heritiera fomes, and S. apetala fruits showed scavenging of 50% DPPH free radicals at 81, 34.7, 61.2, and 33.5 µg powder/mL, respectively. Contents of total polyphenols in these fruits displayed strong positive correlations with reducing power (r2 = 0.97), total antioxidant capacity (r2 = 0.85) and scavenging DPPH free radicals (r2 = 0.85) whereas that for the AgNPs biosynthesis capacity was small (r2 = 0.32). Thus, the aqueous extract of S. apetala fruit is the most potential in antioxidant activity and biosynthesis of AgNPs.