Evaluation of the antioxidant, antibacterial and anticancer (lung cancer cell line A549) activity of Punica granatum mediated silver nanoparticles

Abstract

This work aimed to synthesize silver nanoparticles via an environmentally benign route, using the aqueous extract of Punica granatum as a precursor as well as a stabilizing and reducing agent. The as-synthesized silver nanoparticles were confirmed using UV-visible spectroscopy with an absorbance peak at 450 nm and were thereafter further confirmed using dynamic light scattering (DLS), High Resolution Transmission Electron Microscopy (HR-TEM) and X-Ray Diffraction (XRD). TEM analysis revealed 6-45 nm and spherically dispersed nanoparticles and XRD showed the crystalline nature of the nanoparticles. The free radical scavenging activity of the nanoparticles for DPPH and intracellular reactive oxidative species (ROS) production were observed using dihydroethidium (DHE) non-fluorescent stain and a CellROX® Deep Red fluorescent probe. Antibacterial assays against the most common Gram negative (Escherichia coli) and Gram positive (Staphylococcus aureus) bacteria showed a higher zone of inhibition against S. aureus. Furthermore, the anti-cancerous activity of the biologically synthesized silver nanoparticles was revealed by the inhibited cell growth of lung cancer A549 cells and no cytotoxicity was observed. This may be due to their ability to arrest the cell cycle at G1 phase. Thus, this work provides a gateway to explore more about the anticancer properties of biogenically synthesized silver nanoparticles and these biologically prepared silver nanoparticles have the potential to be utilized in biomedical science.

Fig. 1. Visual representation of the formation of silver nanoparticles.

Fig. 2. UV-vis spectral representation of silver nanoparticles.

Fig. 3. Dynamic light scattering (DLS) of silver nanoparticles.

Fig. 4. X-ray diffraction pattern of silver nanoparticles.

Fig. 5. TEM images of biogenically synthesized silver nanoparticles.

Fig. 6. The antioxidant activity of the S4 AgNPs and the extract using a DPPH assay.

Fig. 7. Intracellular ROS generation. a. The effect of the AgNPs and the extract on H₂O₂ induced free radical production using a DHE assay and b. the effect of the AgNPs and the extract on H₂O₂ and pesticide induced free radical production using the fluorescent probe CellROX® Deep Red.

Fig. 8. Cell viability percentage upon treatment with S4 green AgNPs on (a) hPBMC and (b) A549 lung cancer cell lines at 24, 48 and 72 h.

Fig. 9. a. The effect of AgNPs and the extract on the cell cycle progression with respect to control treatment, b. the DNA content profile of the control, c. the DNA content profile of the AgNPs and d. the DNA content profile of the extract.