Biosynthesis of Zinc Oxide Nanoparticles Using Hertia intermedia and Evaluation of its Cytotoxic and Antimicrobial Activities

The unique properties of zinc oxide nanoparticles (ZnO-NPs) produced using plant extract make them attractive for use in medical as well as industrial applications. In this study, ZnO-NPs were synthesized using Hertia intermedia extract as the reducing and stabilizing agent followed by characterization and evaluation of its biological potency. Field emission scanning electron microscopy (FESEM) image showed spherical nanoparticles with a size range of 20–80 nm. UV-vis spectroscopy displayed absorption peaks at 362.67 nm which is one of the characteristic features of ZnO-NPs. FT-IR spectra confirmed the presence of some phytoconstituents as capping agents to stabilize the nanoparticles. MTT assay showed cytotoxicity of ZnO-NPs against Caco-2 (IC50 177 μg/mL), SH-SY5Y (IC50 184 μg/mL), MDA-MB-231 (IC50 168 μg/Ml, and HEK-293 (IC50 240 μg/mL) cell lines. Using 7-dichlorodihydrouorescein diacetate (DCFH-DA) assay, significant production of reactive oxygen species (ROS) was measured after 24 h of treatment with 200 μg/mL ZnO-NPs that is indicative of ZnO-NP-mediated oxidative stress. Induction of apoptosis/necrosis in ZnO-NPs-treated cells was determined using annexin V-PE/7-AAD staining. Furthermore, expression analysis of pro-apoptotic gene Bax and anti-apoptotic gene Bcl-2 by real-time PCR showed 10-fold increase in expression of Bax and 16-fold decrease in expression of Bcl-2 after exposure of cells to ZnO-NPs. Well diffusion method did not show effective antibacterial activities of synthesized ZnO-NPs against both gram-negative and gram-positive bacteria. All the results confirm that the ZnO-NPs synthesized in the present work are a potential candidate to induce ROS and oxidative stress that lead to cytotoxicity in cell lines.