Dual anti-inflammatory and immunomodulatory effects of clove essential oil and eugenol: targeting neutrophil functions and experimental arthritis.

Polymorphonuclear neutrophils (PMNs) contribute to the pathogenesis of arthritis by releasing excessive reactive oxygen species (ROS) and proteolytic enzymes, leading to joint damage. Targeting PMNs activation represents a promising therapeutic approach. This study aimed to evaluate the immunomodulatory and anti-arthritic effects of clove essential oil (CEO) and its main constituent, eugenol, through in vitro, in vivo, and in silico approaches. CEO chemical composition was determined by GC-MS. In vitro assays assessed PMNs degranulation (lysozyme release) and oxidative burst (NBT reduction), along with antioxidant, anti-hemolytic, and antiplatelet activities. Arthritis was induced in mice by CFA injection, and therapeutic efficacy was evaluated by paw edema, histopathology, and body weight monitoring. Molecular docking was conducted to predict interactions with inflammatory targets (COX-1, COX-2, TNF-α). GC-MS revealed 77.67% eugenol in CEO. Both CEO and eugenol significantly inhibited PMN degranulation (52.81% and 57.54%) and oxidative burst (41.85% and 75.41%; p < 0.001). CEO and eugenol also displayed strong antioxidant and anti-hemolytic activities, and reduced collagen-induced platelet aggregation. In vivo, treatment markedly reduced paw edema and histopathological damage without hepatic toxicity. Docking analysis suggested potential inhibitory interactions with COX-2 and TNF-α. CEO and eugenol exert potent anti-inflammatory and immunomodulatory effects by modulating PMNs activity, preventing oxidative stress, and alleviating arthritis symptoms. These findings highlight their therapeutic potential as natural candidates for managing arthritis and related inflammatory conditions.