Phytochemical Analysis and Antibacterial Activity of Tannins Extracted from Salix alba L. Against Different Gram-Positive and Gram-Negative Bacterial Strains

Abstract

The present study was aimed to extract tannins from methanolic extracts of Salix alba and determination of their antimicrobial potential. Antibacterial activity of tannins extracted from S. alba leaves and stem bark methanolic extracts was determined by using agar well diffusion assay against seven Gram-positive and Gram-negative bacterial strains including Streptococcus pyogenes, Staphylococcus aureus (1), S. aureus (2), Shigella sonnei, Escherichia coli (1), E. coli (2), and Neisseria gonorrhoeae, and zone of inhibition was measured in terms of millimeter. The highest inhibition zone was recorded at 17.33 ± 1.15 by using bark tannins (100 mg/ml) against S. aureus (2) after an incubation period of 48 h while no activity was reported against S. sonnei by using leaves tannins. It was observed that the tannins from the bark of the S. alba were more effective to kill all bacterial pathogens and the inhibition percentage increased with increasing the concentration of the tannins. Major classes of secondary metabolites were determined qualitatively and quantitatively. Leaves fraction of S. alba methanolic extract was enriched with Tannins, Quinones, Steroids, Resins, and Phenols while stem bark extracts were embellished with Flavonoids, Tannins, Quinones, and Phenols. Findings from this study will help to develop formulation from S. alba tannins and endorse the ethnopharmacological utilization of the evaluated plant.