Synergistic Antioxidant and Cytoprotective Effects of Thunbergia laurifolia Lindl and Zingiber officinale Extracts Against PM2.5-Induced Oxidative Stress in A549 and HepG2 Cells

PM2.5, a fine particulate matter, poses considerable health risks. When inhaled, PM2.5 can deeply penetrate the lungs, triggering respiratory issues such as pneumonia and bronchitis, aggravating heart and lung conditions, increasing the risk of lung cancer, causing cardiovascular problems, and affecting the nervous, immune, and reproductive systems. This study investigated the protective effects of the combination extract (CRGE) of <i>Thunbergia laurifolia</i> Lindl. (Rang Chuet) water extract (RWE), and <i>Zingiber officinale</i> (ginger) ethanol extract (GEE) against PM2.5-induced oxidative stress in A549 and HepG2 cells. CRGE exhibited superior cytoprotective effects compared to the single extracts (RWE and GEE) by significantly reducing PM2.5-induced cytotoxicity and reactive oxygen species production while enhancing antioxidant enzyme activity. To investigate the effects of PM2.5 exposure on cellular responses, gene expression analysis was conducted on a panel of antioxidant enzymes (heme oxygenase 1, superoxide dismutase, catalase, and glutathione peroxidase), the phase II detoxification enzyme NQO1, and the inflammatory markers interleukin (IL)-6 and IL-8 using the A549 and HepG2 cell lines. CRGE treatment effectively reversed the PM2.5-mediated changes in gene expression in both cell lines, suggesting that it may help restore cellular antioxidant defense mechanisms and mitigate PM2.5-induced oxidative stress. This study showed that CRGE holds promise as a natural antioxidant and cytoprotective agent against PM2.5-induced oxidative stress. Further studies are required to investigate the underlying mechanisms and confirm the efficacy of CRGE in vivo.