Biogenic fabrication and characterization of Silver nanoparticles using high altitude lichen Heteroderimia leucomela extract and its potential applications

Abstract

Lichens are symbionts formed from the intimate union of fungi and algae and are enriched with distinct phytocompounds. Plants, bacteria, fungi and algae have been extensively explored for metallic nanoparticle synthesis but the use of lichens in the field of nanotechnology remains less explored. In the present study, Silver nanoparticles (Ag NPs) were synthesized using Heteroderimia leucomela lichen extract and characterized using different techniques. GC–MS analysis was performed to identify the phytocompounds supporting the synthesis of Ag NPs as capping and reducing agents. The antioxidant and antimicrobial activities were evaluated by in-vitro assays. Results showed that the synthesized Ag NPs had an average particle size of 20 ± 0.2 nm and were predominantly spherical in shape. The synthesized Ag NPs exhibited significant free radical scavenging activity for 2,2-diphenyl-1-picrylhydrzyl (DPPH) radicals with an IC50 value of 7.5 ± 0.1 μg/ml. The antibacterial activity of the synthesized Ag NPs against the test organisms were observed as follows: E. coli ≥ B. subtilis ≥ V. cholera ≥ S. pneumonia ≥ P. aeruginosa and the results of anticandida activity revealed that the candida strains were susceptible in the following order: C. albicans ≥ C. glabrata ≥ C. parapsilosis ≥ C. krusei ≥ C. tropicalis. Thus Ag NPs synthesized from high altitude lichen extract demonstrated that it has potent antioxidant and antimicrobial activities with greater importance to the field of nanomedicine.