Abstract

Facile synthesis of silver nanoparticles was attempted using soil derived Streptomyces sp. KBR3 and its antimicrobial, antioxidant and antiproliferiative properties were evaluated in vitro. The extracellular synthesis of silver nanoparticles by the biomass of Streptomyces sp. KBR3 was confirmed through visual color change and ultraviolet-visible spectral analysis. Results of transmission electron microscopy, selected area electron diffraction and X-ray diffraction analysis showed the crystalline polydispersed spherical shaped nanoparticles with the size of 36 nm. Fourier-transform infrared spectroscopy analysis suggested the role of water soluble polyols present in the Streptomyces sp. KBR3 in mediating the synthesis of silver nanoparticles. The synthesized silver nanoparticles showed significant antibacterial activity against Staphylococcus aureus and Escherichia coli. In antioxidant studies, the silver nanoparticles showed maximum scavenging effects of 84 %±1.22 %, 95.8 %±1.32 % and 57.85 %±0.54 % at 1000 μg/ml in 2,2-diphenyl-1-picrylhydrazyl, 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) and metal chelating assay with the half-maximal inhibitory concentration value of 40 μg/ml, 15 μg/ml and 53 μg/ml, respectively. In antiproliferiative study on H357 oral cancer cell line, the silver nanoparticles showed 77.21 %±0.43 % reduction in cell viability at 250 μg/ml with the half-maximal inhibitory concentration values of 9.431 μg/ml. The present study showed that the silver nanoparticles synthesized using the Streptomyces sp. KBR3 might be a promising material for different biomedical applications.