Barleria acanthoides Vahl. Mediated Green Synthesis of Silver Nanoparticles and their Antibacterial Activity

Barleria acanthoides Vahl members of the Acanthaceae are plants of the old world, found in the regions of Africa, the Arab peninsula and Southeast Asia. The plant contains several phenolic compounds, antioxidants, and secondary metabolites that can assist in the synthesis of silver nanoparticles (SNPs). Therefore, in the present study, B. acanthoides was explored for the utilization of B. acanthoides extract for the synthesis of stable SNPs as well as for their antibacterial properties. The AgNO3 solution (5 mM) and plant leaf extract at a ratio of 9:1 were mixed for the preparation of reaction mixture. The green synthesis of SNPs was achieved when the reaction mixture was heated at 90oC for 5 min. The synthesized SNPs were characterized by UV-vis spectroscopy, FTIR, SEM, and DLS analysis. Furthermore, the SNPs were evaluated for their antibacterial potential by a well diffusion against Staphylococcus aureus ATCC 29213, Bacillus subtilis (ATCC 6633), Pseudomona aeruginosa (ATCC 27853), and Escherichia coli (ATCC 25922). The minimum inhibitory concentration (MIC) of the SNPs against bacteria was also evaluated. The SNP synthesis mediated by B. acanthoides was simple, quick, and risk-free. The characterization of SNPs by various analyses showed that the SNPs were spherical with an average size of 45.15 nm. The SNPs showed broad spectrum antibacterial properties. A maximum zone of inhibition was observed against E. coli (33.75 mm), followed by P. aeruginosa (16.67 mm), S. aureus (16.5 mm), and B. subtilis (14.33 mm). The MIC value of SNPs was found to be 1.56 μl /ml for E. coli, P. aeruginosa, and B. subtilis, while the MIC value for S. aureus was 3.125 μl /ml.

Conclusion: B. acanthoides can be explored further for the non-hazardous, eco-friendly synthesis of SNPs for medical and therapeutic uses.