P23-19 Oxidative Effects of Silica and Carbon NanoparticleExposure in A549 Cells: Potential Protective Role of Melatonin

The potential diseases and health risks faced by miners are primarily associated with the inhalation of various dust particles that can lead to respiratory disorders. The atmosphere in coal mines contains numerous nanoparticles, including silica and carbon. This respir-able coal dust can induce lung toxicity through multiple mechanisms, resulting in chronic occupational diseases. In this study, we aimed to investigate the toxicity mechanisms – particularly oxidative stress -induced by such exposure, and to assess how combined exposure to silica and carbon nanoparticles influences toxicity. Additionally, we evaluated the potential protective effects of melatonin, known for its antioxidant properties. The effects of exposure to nano-carbon (24 hours), nano-silica (24 hours), and melatonin (6 hours) on cell viability were assessed using the MTT method (n=12). The exposure doses were selected based on the inhibitory concentration 20 (IC20) of each nanoparticle. To evaluate the protective effects of melatonin, pre-treatment with melatonin (at a concentration that does not affect cell viability) was applied to some groups for 6 hours. The experimental groups (n=3) were as follows: control, carbon, silica, carbon+silica, melatonin, melatonin/ carbon, melatonin/silica, and melatonin/carbon + silica. Oxidative damage in the groups was assessed by measuring levels of reactive oxygen species (ROS), glutathione (GSH), and 4-hydroxynonenal (4-HNE). Commercial kits were used for these measurements. Data were analyzed using GraphPad Prism Software (Version 10.2.3). Following 24-hour exposure of A549 cells, the IC20 concentrations were determined as 393.83 µM for nano-silica and 205.16 µM for nano-carbon. Additionally, a protective dose of melatonin (10 s mM) that did not affect cell viability was identified. At the defined doses and exposure durations, the results showed that both single and combined nanoparticle exposures significantly increased ROS levels in the cells compared to the control group, while GSH levels were significantly reduced in the nano-silica and combined exposure groups (p<0.05). Moreover, melatonin was found to exert a protective effect on these parameters. No significant changes were observed in 4-HNE levels among the groups. Overall, the findings suggest that exposure to coal dust containing combined nanoparticles may induce greater oxidative damage in the lungs of workers compared to control and single exposures, and that protective agents such as melatonin may be effective in preventing such damage.