Antileishmanial, antioxidant and anti-hemolytic activities of green synthesized ZnO nanoparticles mediated by Teucrium stocksianum Boiss leaf extract

Cutaneous leishmaniasis is the most common form of the vector borne parasitic disease, causing skin lesion and ulcer. Several studies have reported the resistance of cutaneous leishmaniasis parasite to antimonial drugs. Hence, there is a need to develop cheaper and effective alternative therapies for resistance breakdown. In the current study we report the effectiveness of Teucrium stocksianum extract mediated green synthesized zinc oxide nanoparticles (ZnONPs) against Leishmania tropica (KMU25), a causative species of cutaneous leishmanaisis. ZnONPs was successfully synthesised at 70 °C by continuous stirring (2 h) of aqueous extract (5 mg/mL) and Zinc acetate solution (2 g/50 mL, pH: 8) in 1:9. The characterization of these NPs showed a UV-Vis surface plasmon resonance at 365 nm, hexagonal morphology with irregular shapes through scanning electron microscopy, average crystal size 21.48 ± 5.2 nm through XRD analysis and the complex metabolites attachments to the surface of the particles was confirmed by FTIR. The DPPH (2,2-diphenyl-1-picrylhydrazyl) assay-based antioxidant activity showed 50% free radical scavenging at 624.94 µg/mL and 798.45 µg/mL for extract and ZnONPs, respectively. The hemolysis assay revealed moderate cytotoxicity with a LD50 value of 3807.54 µg/mL and 1537.16 µg/mL for the extract and ZnONPs, respectively. The antileishmanial activities were examined at different concentration (50, 100, 250, 500, and 1000 µg/mL) using MTT cell viability assays. The LD50 values 1895.63 µg/mL (for extract) and 837.07 µg/mL (for extract mediated ZnONPs) were estimated, showing enhanced antileishmanial activity of ZnONPs compared to the extract. Moreover, the ZnONPs were nontoxic towards normal RBCs, making it a potential candidate as an interesting topical nanomedicine against cutaneous leishmaniasis.