In vitro and in vivo anti-parasitic activity of biogenic antimony sulfide nanoparticles on Leishmania major (MRHO/IR/75/ER).

The aims of this study were to produce biogenic antimony sulfide nanoparticles (NPs) using Serratia marcescens (S. marcescens) and investigate the potential anti-leishmanial effects of these NPs on Leishmania major (L. major) (MRHO/IR/75/ER) in both in vitro and in vivo experiments. Biogenic antimony sulfide NPs were synthesized through intracellular biological methods using S. marcescens. The efficiency of various concentrations of antimony sulfide NPs was assessed using in vitro experiments on amastigotes of L. major at various times post-infection. In vivo experiments were carried out in BALB/c mice inoculated subcutaneously with 2 × 106L. major promastigotes (MHROM/IR/75/ER) and treated with antimony sulfide NPs (70 μg/mL, tropically), meglumine antimoniate (glucantime) as positive control and sterile phosphate-buffered saline (PBS, pH 7.4) as vehicle control. Results of in vitro experiments revealed that the anti-leishmanial activity increased when the antimony sulfide NPs concentration increased. The IC50 (50% inhibitory concentration) of antimony sulfide NPs against amastigotes was calculated as 62.5 μg/mL. In in vivo experiments, the average size of lesions significantly decreased to 8.6 ± 2.7 mm2 in mice inoculated with L. major promastigotes and treated with antimony sulfide NPs, compared with that in the negative control group (P = 0.015). Furthermore, results showed that antimony sulfide NPs significantly decreased the parasite load in the test group, compared with the negative control group (P = 0.001). Various concentrations of antimony sulfide NPs showed a great anti-leishmanial efficiency against L. major (MRHO/IR/75/ER), with the greatest efficiency shown by a concentration of 62.5 μg/mL in in vitro and in vivo experiments.