Abstract

Silver Nanoparticles (Ag-NPs) are progressively exercised as an antimicrobial agent among myriad applications. The rapid emergence of microbial resistance to conventional antibiotics by multidrug-resistant pathogens has become a threat to the global health community. Traditionally used herbal plants are good sources of bioactive phytochemicals and Galinsoga formosa is one of them. Thus, Ag-NPs are biologically synthesized, intending to evaluate the antibacterial activity of G. formosa. Disc diffusion assay was used to assess the antibacterial activity of leaf and flower crude extracts distinctly as well as of green synthesized Ag-NPs in vitro. The biosynthesis of Ag-NPs was primarily confirmed by brownish color solution and later by UV-Visible spectrophotometer. Ag-NPs synthesized from G. formosa leaf, and flower extract showed antibacterial activity against gram-positive (S. aureus, S. mutans, and S. epidermidis) and gram-negative (K. pneumoniae and P. aeruginosa) bacteria, where gram-negative bacteria were more sensitive than gram-positive bacteria. The highest zone of inhibition was observed against P. aeruginosa (13.33±0.58 mm) by applying Ag-NPs synthesized from G. formosa flower extract. In contrast, the lowest zone of inhibition was observed against S. epidermidis (6.33±0.58 mm). Antibacterial activity of Ag-NPs from flower and leaf extracts was considerably higher as compared to their respective crude extract. Further, Ag-NPs from the flower extract was exhibited more growth inhibitory response than the leaf extract. Hence, the findings of this research suggested that the synthesized Ag-NPs from G. formosa leaf and flower extract were exhibited antibacterial activity. Such synthesized Ag-NPs might help to develop new drug for combating against various diseases.

Key words: G. formosa, leaf and flower extracts, silver nanoparticle, antibacterial activity