Green synthesis of silver nanoparticles from medicinal plants and evaluation of their antiviral potential against chikungunya virus.

The exploration of nanoscale materials for their therapeutic potential against emerging and re-emerging infections has been increased in recent years. Silver nanoparticles (AgNPs) are known to possess antimicrobial activities against different pathogens including viruses and provide an excellent opportunity to develop new antivirals. The present study focused on biological synthesis of AgNPs from Andrographis paniculata, Phyllanthus niruri, and Tinospora cordifolia and evaluation of their antiviral properties against chikungunya virus. Synthesized plants AgNPs were characterized to assess their formation, morphology, and stability. The cytotoxicity assays in Vero cells revealed that A. paniculata AgNPs were most cytotoxic with maximum non-toxic dose (MNTD) value of 31.25 μg/mL followed by P. niruri (MNTD, 125 μg/mL) and T. cordifolia AgNPs (MNTD, 250 μg/mL). In vitro antiviral assay of AgNPs based on degree of inhibition of cytopathic effect (CPE) showed that A. paniculata AgNPs were most effective, followed by T. cordifolia and P. niruri AgNPs. The results of antiviral assay were confirmed by cell viability test using 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) dye, which revealed that A. paniculata AgNPs inhibited the virus to a maximum extent. The cell viability of CHIKV-infected cells significantly increased from 25.69% to 80.76 and 66.8%, when treated with A. paniculata AgNPs at MNTD and ½MNTD, respectively. These results indicated that use of plants AgNPs as antiviral agents is feasible and could provide alternative treatment options against viral diseases which have no specific antiviral or vaccines available yet.