α-Phellandrene, a cyclic monoterpene, attenuates inflammatory response through neutrophil migration inhibition and mast cell degranulation

AimsWe aimed to investigate the modulating effect of α-phellandrene on neutrophil migration and mast cell degranulation processes.Main methodsMale Wistar rats or Swiss mice were treated p.o. with vehicle (3% Tween 80, p.o.), α-phellandrene (50, 100, or 200 mg/kg, p.o.), or dexamethasone (0.5 mg/kg, p.o.) 1 h before carrageenan injection. Then, the neutrophil migration in 6-day-old air pouches or peritoneal cavities. The leukocyte rolling and adhesion were measured in real time and assessed by intravital microscopy. ELISA was used to detect TNF-α and IL-6 in peritoneal lavage. Compound 48/80–induced mast cell degranulation was assessed in mesenteric rat tissues.Key findingsIn all the tested doses, α-phellandrene prevented carrageenan-induced neutrophil accumulation (P < 0.05). As detected by intravital microscopy, α-phellandrene also inhibited leukocyte rolling and adhesion, as well as significantly inhibited the production of the pro-inflammatory cytokines TNF-α and IL-6. Moreover, the degranulation of compound 48/80–induced mast cells was also inhibited by α-phellandrene (P < 0.001).SignificanceThese results suggest that α-phellandrene plays an important role as an anti-inflammatory agent through neutrophil migration modulation and mast cell stabilization.