Therapeutic potential of biogenic silver nanoparticles in murine cutaneous leishmaniasis

In the last years, silver nanoparticles have appeared as novel antimicrobial agents. In this work, we evaluated the therapeutic potential of silver nanoparticles prepared by two different processes: 1) chemical synthesis (Chem-AgNP); and 2) biosynthesis from the fungus Fusarium oxysporum (Bio-AgNP), in the treatment of cutaneous leishmaniasis. When tested in vitro against Leishmania amazonensis promastigotes, Bio-AgNP was 4-fold more potent than Chem-AgNP (IC50 = 25 uM and 100 uM, respectively). In vivo studies in mice infected in the ear showed that bi-weekly intralesional injections with only 6.5 ug/Kg of body weight of Bio-AgNP during 4 weeks were equally effective as 300-fold higher doses of the reference drug amphotericin B, and more effective than 3-fold higher doses of Chem-AgNP. Contrary to the hepato- and nephrotoxicity that resulted from amphotericin B treatment, and the slight hepatotoxicity produced by Chem-AgNP, no changes in serum levels of AST, ALT and creatinine were detected with Bio-AgNP. Together, these findings show that the biogenic synthesis resulted in enhanced in vitro and in vivo antileishmanial activities, and safer silver nanoparticles as compared with the chemical synthesis.