Assessing the biomedical applicability of biogenically synthesized AuNPs using Salvia splendens extract

Abstract

This study reports the multifunctional potential of gold nanoparticles (AuNPs) biosynthesized by using Salvia splendens leaf extract (SSLE). The biosynthesized AuNPs were characterized by UV–Visible spectroscopy, transmission electron microscopy (TEM), and dynamic light scattering, followed by the assessment of their anti-cancer, anti-oxidant, anti-inflammatory and anti-bacterial potentials. The biosynthesized SSLE-AuNPs showed a characteristic absorbance peak at 559 nm that corresponds to the surface plasmon resonance (SPR) band of the AuNPs. The zeta potential of SSLE-AuNPs was estimated to be ‒ 21 ± 1.9 mV, and TEM analysis confirmed the particles to be spherical with an average size of 94.8 ± 5.1 nm. The SSLE-AuNPs exhibited dose-dependent antioxidant activity, with IC50 values of 218.5 ± 4.2 µg/mL (DPPH) and 185.3 ± 3.7 µg/mL (ABTS), compared to ascorbic acid (32.1 ± 1.8 µg/mL and 28.6 ± 1.5 µg/mL, respectively. In addition, SSLE-AuNPs exerted potent anti-bacterial effect against Staphylococcus aureus (MIC50 68 ± 2.1 μg/mL) and Klebsiella pneumoniae (MIC50 82 ± 2.3 μg/mL), which was comparable to that of the standard antibacterial agent, tetracycline. Moreover, SSLE-AuNPs induced significant reduction in cellular viability of A549 cells at concentrations of 100, 200 and 400 μg/mL, respectively (p < 0.001). Such cytotoxic potential of SSLE-AuNPs was accompanied by considerable instigation of nuclear fragmentation and condensation, caspase activation, and ROS generation in A549 cells. Furthermore, in vitro studies highlighted the anti-inflammatory potential of SSLE-AuNPs on murine alveolar macrophages (J774A.1) via deflating inflammatory mediators such as the proinflammatory cytokines. To sum up, the present findings have substantiated the antioxidant, antibacterial, anticancer and antiphlogistic properties of SSLE-AuNPs, paving the way for subsequent investigations into green synthesized nano-formulations.