An Investigation of the Cytotoxicity and Caspase-Mediated Apoptotic Effect of Green Synthesized Zinc Oxide Nanoparticles Using Eclipta prostrata on Human Liver Carcinoma Cells

Abstract

Cancer is a leading cause of death worldwide and sustained focus is on the discovery and development of newer and better tolerated anticancer drugs, especially from plants. In the present study, a simple, eco-friendly, and inexpensive approach was followed for the synthesis of zinc oxide nanoparticles (ZnO NPs) using the aqueous leaf extract of Eclipta prostrata. The synthesized ZnO NPs were characterized by UV-visible absorption spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX), High-resolution transmission electron microscopy (HRTEM), and Selected area (electron) diffraction (SAED). The HRTEM images confirmed the presence of triangle, radial, hexagonal, rod, and rectangle, shaped with an average size of 29 ± 1.3 nm. The functional groups for synthesized ZnO NPs were 3852 cm^-1 for H-H weak peak, 3138 cm^-1 for aromatic C-H extend, and 1648 cm^-1 for Aromatic ring stretch. The 3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide (MTT), caspase and DNA fragmentation assays were carried out using various concentrations of ZnO NPs ranging from 1 to 100 mg/mL. The synthesized ZnO NPs showed dose dependent cytopathic effects in the Hep-G2 cell line. At 100 mg/mL concentration, the synthesized ZnO NPs exhibited significant cytotoxic effects and the apoptotic features were confirmed through caspase-3 activation and DNA fragmentation assays.

Keywords: Eclipta prostrata; anticancer actions; caspase study; zinc oxide nanoparticles.

Figure 1

UV-Vis spectral analysis and color intensity of biosynthesized NPs at various time intervals of synthesized ZnO NPs at 120 min. The inset shows the color change from yellow to ruby-red in color.

Figure 2

(a) X-ray diffraction (XRD) patterns of biosynthesis of ZnO NPs using aqueous extract of E. prostrate;(b) Fourier transform infrared spectroscopy (FTIR) peaks of synthesized ZnO NPs using E. prostrata aqueous leaf extract.

Figure 3

(a) SEM micrograph showed the synthesized of ZnO NPs using E. prostrata leaf aqueous extract; (b) EDX analysis showing the chemical composition of synthesized ZnO NPs.

Figure 4

(a) High-resolution transmission electron microscopy (HRTEM) image showing synthesized ZnO NPs from E. prostrata leaf extract; (b) Selected area of electron diffraction pattern (SAED) of the synthesized ZnO NPs showing the rings.

Figure 5

(a) Caspase-3, Caspase-8 and Caspase-9 activity of synthesized ZnO NPs; (b) DNA fragmentation: M is 100 bp DNA ladder used as a marker DNA; 1-Control (medium); 2-Camptothecin treated; 3-Doxorubicin treated and 4-DNA of ZnO NPs treated cells showing a large DNA ladder indicates more apoptosis.