Cytoprotective Effects of Microalgal Extracts on H 2 O 2 -Induced Oxidative Stress in Human Lung Adenocarcinoma A549 Cell Line

The body's innate defences often fall short in combating oxidative stress in cells, highlighting the importance of integrating antioxidants from natural sources for preventative healthcare and nutrition. Microalgae-derived compounds like carotenoids and EPA-rich fatty acids play a critical role in protecting cells from oxidative stress. This study evaluated the antioxidant and cytoprotective properties of diethyl ether (Et ₂ O) extracts prepared from the biomass of the microalgae Cyanophora paradoxa, Tetraselmis chuii and Phaeodactylum tricornutum , which were supplemented to human lung cancer cells (A549) experiencing oxidative stress. The extracts of T. chuii and C. paradoxa exhibited higher antioxidant content (123 and 150 µmol Trolox equivalent mg/Recovered Dried Material (RDM)) as compared to P. tricornutum when analysed using the FC assay. All extracts (150 µg mL ^− 1 ) demonstrated protective effects by attenuating H ₂ O ₂ -induced oxidative stress in A549 cells, as confirmed by the MTS (≤ 105% increase in cell growth) and DCF-DA assays (≤ 58% decrease in ROS production). RT-qPCR analysis revealed significant changes in the expression of apoptosis regulatory genes, with a decrease in the pro-apoptotic BAX gene (< 50%) and an increase in the anti-apoptotic Bcl-2 gene expression (> 200%), when cells were treated with extracts compared to cells treated with medium only after exposure to H ₂ O ₂ . These findings suggest that the microalgal extracts successfully mitigated the H ₂ O ₂ -induced oxidative stress in the A459 cells, likely attributable to their inherent antioxidative and apoptosis regulating properties. These attributes, which appear to restore homeostasis, present promising avenues for use in cosmetics and therapeutic contexts.