Green synthesis and antibacterial effect of silver nanoparticles using Mentha piperita L and Mentha spicata L. extracts.

Silver nanoparticles (AgNPs) are used as a medicinal tool for infections against microbes. Most bacteria have been resistant to antibiotics and in the near future, there is an urgent need to replace antibiotics with new substances with antibacterial properties. This study aimed to the biosynthesis of silver nanoparticles (AgNPs) using aqueous and methanol extract of Mentha piperita L and Mentha spicata L and determined of antibacterial activity of produced AgNPs.

An environmentally friendly extracellular biosynthetic technique was used for the production of AgNPs. The reducing agents used to produce the nanoparticles were from the aqueous and methanol extract of Mentha piperita L and Mentha spicata L. The AgNPs were characterized by color changes, FTIR analysis, and UV-visible spectroscopy. The antibacterial activity of AgNPs was investigated through bacteria disc fusion assays.

An absorption peak at 420 nm and the color change to dark brown were corresponding to the plasmon absorbance of AgNPs and then were performed by the FTIR method. Silver nanoparticles synthesized with Mentha piperita L and Mentha spicata L extracts against Staphylococcus aureus had better inhibitory activity than Escherichia coli. In the case of Staphylococcus aureus culture medium, aqueous and alcoholic extracts with 10 gr of extracted material, had the highest and lowest diameter of growth inhibition zone, respectively (P=0.05).

The results confirmed that extracellular synthesis of AgNPs mediated by Mentha piperita L and Mentha spicata L. extract indicated a good bactericidal activity against the tested bacteria and can be used in various fields as an antibacterial agent.