Understanding the characteristics of phytofabricated silver nanoparticles and their leishmanicidal potential against Indian strain of Leishmania donovani

The present study was implemented to synthesize green silver nanoparticles from aqueous leaf extract of Nyctanthes arbor-tristis (AgNPs) and to analyze their physicochemical properties in evaluating their antileishmanial activity. Formation of AgNPs from leaf extract (LE) was evidenced by the change of peak intensity in the fluorescence spectrum. The particles were nearly monodispersed (PDI = 0.134) with hydrodynamic diameter of 67.83 nm and appeared quite stable (zeta potential = −19.1 mV). FESEM study demonstrated nearly spherical shape of AgNPs and apparently smooth surface area was identified by AFM. The diameter of AgNPs (~ 21 nm) was measured by HRTEM. The amorphous crystal nature, polycrystallinity and low grain size of AgNPs were comprehended by the XRD. The crystalline nature was supported from SAED profile. The EDX spectra identified the constituents of AgNPs whereas the XPS spectra unraveled the AgO state. The FTIR analysis implemented the phytofabricating agent(s) to be attached to the Ag via carboxyl group. The leishmanicidal activity of AgNPs on Leishmania donovani (MHOM/IN/1983/AG83) was compared with commercial silver nanoparticles (AgNPs), AgNO, miltefosine and leaf extract (LE). The AgNO (IC = 0.469 ± 0.116 μg/ml), AgNPs (IC = 4.74 ± 0.221 μg/ml), miltefosine (IC = 0.87 ± 0.038 μg/ml) proved their better leishmanicidal efficacy than AgNPs (IC = 11.46 ± 0.120 μg/ml) and LE was found to be incompetent as parasiticidal. However, AgNPs showed greater safety level (IC = 136.33 ± 0.881 μg/ml) in normal macrophages (Raw 264.7) than AgNO (IC = 1.81 ± 0.133 μg/ml), AgNPs (IC = 10.06 ± 0.719 μg/ml) and miltefosine (IC = 18.73 ± 0.9 μg/ml). Altogether, this study revealed the physicochemical properties of AgNPs and their biocompatibility in killing L. donovani promastigotes indicating their new identity as potential antileishmanial agent.