Green synthesis of silver nanoparticles using phlomis leaf extract and investigation of their antibacterial activity

In recent years, the green synthesis of silver nanoparticles using various plant extracts has attracted great attention. This is because, these methods are simple, inexpensive and, eco-friendly. In this study, it was observed that silver ions were reduced by phlomis leaf extract after 5 min, leading to the formation of crystalline silver nanoparticles. Phlomis species is known as a rich source of flavonoids, phenylpropanoids and other phenolic compounds. The silver nanoparticles produced by the phlomis extract were characterized by different techniques including UV-vis spectrophotometry, X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and FT-IR. The SEM and TEM results indicated that AgNPs were predominantly spherical in shape with an average particle size of 25 nm. In addition, the antibacterial activity of biologically synthesized nanopartilcles against Gram-positive (Staphyloccocus aureus and Bacillus cereus) and Gram-negative (Salmonella typhimurium and Escherichia coli) bacteria was proved. This study, therefore, showed that the phlomis leaf extract could be used for the green synthesis of silver nanoparticles with the appropriate antibacterial activity.