Microwave-assisted biosynthesis of zinc nanoparticles and their cytotoxic and antioxidant activity

The present study was designed for microwave assisted synthesis of zinc nanoparticles (Zn NPs) using Lavandula vera leaf extract in the presence of ZnSO4 (1 mM). The biogenic Zn NPs were then characterized using scanning electron microscopy (SEM), energy dispersive X-ray (EDX), X-ray diffraction spectroscopy (XRD), UV-visible spectroscopy, and Fourier transform infrared spectroscopy (FTIR) techniques. Thereafter, the cytotoxic effect of ZnSO4 and Zn NPs on different cell lines was investigated by MTT-based cytotoxicity assay and their antioxidant properties were assessed using DPPH scavenging activity and reducing power assay. The SEM micrograph showed that the Zn NPs had spherical shape with the size range of 30-80 nm. For A549, MCF-7, HT-29, and Caco-2 cell lines treated with Zn NPs, the concentration necessary causing 50% cell death (IC50) was found to be 22.3 +/- 1.1 mu g mL(-1), 86 +/- 3.7 mu g mL(-1), 10.9 +/- 0.5 mu g mL(-1), and 56.2 +/- 12.8 mu g mL(-1), respectively. In the case of ZnSO4, the same results (IC50) were observed at concentration of 81.6 +/- 1.3 mu g mL(-1) (A549), 121.0 +/- 2.4 mu g mL(-1) (MCF-7), 43.0 +/- 1.4 mu g mL(-1) (HT-29), and 85.7 +/- 2.3 mu g mL(-1) (Caco-2). The obtained results of antioxidant activity showed that the IC50 values of butylated hydroxyanisole (BHA) and Zn NPs were 44 mu g mL(-1) and 65.3 mu g mL(-1), respectively, while ZnSO4 at concentration of 200 mu g mL(-1) exhibited only 10.9% DPPH radical scavenging effect. Moreover, the reducing power of Zn NPs and BHA were significantly higher than ZnSO4 (p < 0.05). To sum up, application of L. vera leaf extract combined with microwave heating energy led to simple and fast formation of Zn nanostructures exhibited higher antioxidant and cytotoxic activity compared to soluble Zn+2 ions. However, identification of the related mechanisms merit further studies. (C) 2016 Published by Elsevier GmbH.