Bioactive compounds in the modulation of oxidative stress in monocytes and macrophages.

Human immunity involves both innate and adaptive defence mechanisms, with inflammation playing a central role in responding to cellular injury, pathogenic infections, and allergic stimuli. Reactive oxygen species (ROS) are closely associated with the onset and progression of inflammation. While moderate ROS levels function as crucial signalling molecules, excessive ROS can damage cellular components. This study aimed to evaluate the anti-inflammatory and antioxidant potential of plant-derived bioactive compounds including chlorogenic acid, oleuropein, tomatine, and tyrosol using human monocytic cell models (U-937 and THP-1). Differentiation of U-937 and THP-1 cells was induced prior to treatment with the selected bioactive compounds. Cell morphology and integrity were examined utilizing confocal microscopy. Gene expression stability was evaluated using reference genes β-actin and glyceraldehyde 3-phosphate dehydrogenase (GAPDH). Protein expression levels of key inflammatory markers were determined by Western blot analysis. In addition, molecular docking studies were conducted to assess the binding affinity of the compounds to human target proteins [Interleukin-4 (IL-4), 5-Lipoxygenase (LOX-5), Myeloperoxidase (MPO), and Tumor necrosis factor-alpha ( TNF-α)]. No cytotoxic effects were observed in treated cells, and GAPDH was confirmed as a stable reference gene under all experimental conditions. In U-937 cells, treatment with the bioactive compounds led to increased expression of the anti-inflammatory cytokine IL-4 and decreased expression of MPO. Notably, exposure to chlorogenic acid and tyrosol reduced MPO activity. Oleuropein and tyrosol demonstrated a strong suppressive effect on the expression of LOX-5, an enzyme responsible for leukotriene production. All tested bioactive compounds significantly reduced the phorbol 12-myristate 13-acetate (PMA) induced increase in LOX-5 activity. Molecular docking supported the potential of these compounds to interact with key inflammatory proteins, contributing to reduced oxidative stress. The plant-derived compounds, particularly oleuropein and tyrosol from olives, exhibit promising anti-inflammatory and antioxidant effects by modulating ROS-associated signalling pathways and downregulating inflammatory markers. These findings support the therapeutic potential of agricultural waste-derived bioactive in inflammation management and oxidative stress regulation.