Reconnoitring the antioxidant and antibacterial potential of different fruits after tannin acyl hydrolase mediated biotransformation

ABSTRACT Condensed and hydrolyzable tannins are secondary metabolites present in almost every plant part. Tannase enzyme acts on hydrolyzable tannins to produce gallic acid and tannase‐mediated end‐products with immense therapeutic potential. Seven different fruits with significant presence of hydrolyzable tannin content were selected to check for phenol, tannin, and hydrolyzable tannin contents. Prunus domestica had the maximum phenol content, that is, 85.4 ± 0.207, followed by Syzygium cumini, Fragaria ananassa, Rubus fruticosus, and Psidium guajava. Plum showed the maximum number of hydrolyzable tannins. Fruit extracts were subjected to tannase hydrolysis and their antimicrobial and antioxidant activities were determined. There was a significant increase in the antioxidant abilities of the fruits with Punica granatum extract, displaying the highest decline of 132 units of IC50 followed by F. ananassa hydrolyzable extract, showing a decrease from 224.75 to 119.98 μg/mL. The extracts also depicted a significant increase in antibacterial activity after hydrolysis against Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis, and Staphylococcus aureus with Rubus idaeus aqueous extract observed to be most effective against E. coli. The increase in antioxidant and antibacterial activity can be attributed to the production of tannase‐mediated products formed after the biotransformation of hydrolyzable tannins present in the aqueous extracts.