Cissus antractica-ZnO NPs Induce Apoptosis in A549 Cells through ROS-Generated p53/Bcl-2/Bax Signaling Pathways and Inhibition of Inflammatory Cytokines

Abstract

Biogenic synthesis using medicinal plants has less harmful effects as compared to the chemical synthesis of nanoparticles. Here, for the first time, we successfully demonstrated the eco-friendly synthesis of zinc oxide nanoparticles (ZnO NPs) using an aqueous extract of Cissus antractica. The green synthesis method offers great potential for developing new medications that enhance drug bioavailability. The current work highlighted the cytotoxicity, cell death, and routes of apoptosis in lung cancer cells (A549) and inflammatory effects through synthesizing zinc oxide nanoparticles (ZnO NPs) from the Cissus antractica plant using an eco-friendly methodology. UV–visible (UV-Vis) spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FT-IR), and energy-dispersive X-ray spectroscopy (EDS) were also used to characterize the synthesized ZnO nanoparticles. The average size of the NPs was 100 nm, and the NPs were crystalline in nature, as confirmed by FE-TEM and XRD analysis, respectively. In addition, the morphology of the nanoparticles analyzed by FE-TEM showed a spherical shape. The cell viability assay indicated that CA-ZnO NPs are non-toxic to normal cell lines at concentrations up to 20 µg/mL but showed significant toxicity in the A549 cell line. The nanoformulation also increased the ROS generation level in A549 lung cancer cells, and cellular apoptosis was confirmed via Hoechst and PI staining. The CA-ZnO NPs showed significant colony inhibition as well as cell migration ability that highlighted the CA-ZnO NPs as an anticancer agent. Additionally, this study demonstrated that NPs reduced the production of reactive oxygen species (ROS) and enhanced the expression of genes for BAX accumulation by releasing Cyto-c, but decreased Bcl-2 gene expression via the mitochondrial-mediated apoptosis pathway. In addition, the anti-inflammatory effect was also investigated; the CA-ZnO NPs showed significant NO inhibition ability with suppression of pro-inflammatory cytokines (TNF-α, iNOS, COX-2, IL-6, IL-8). In conclusion, Cissus antractica can be a source of significant Nano drugs with more advanced research in order to develop future anti-inflammatory and anticancer medications.