the suppression of adjuvant-induced inflammation and the inhibition of the serum and tissue il-17, tnf-α and il-1β levels by thymol and carvacrol

Background and aim: thymol and carvacrol are two important components of thyme that have multiple medicinal uses. this study investigates the in vivo effects of these natural products on adjuvant-induced inflammation and secretion of interleukin (il)-17 and key inflammatory cytokines in rats. materials and methods: we injected complete freund’s adjuvant (cfa) into the hind paws of rats in order to induce inflammation. each of the cfa-treated rat groups received gavages of thymol, carvacrol, or vehicle (cfa-only group). rats’ paws and ankle edema were measured and then we were able to determine an inflammatory score based on the results. after 72 h of inflammation induction, sera were collected and subsequently inflamed tissue extracts were prepared for cytokine assay by elisa. results: both components significantly decreased paw edema in rats (p<0.01). thymol decreased ankle edema to 61.6% of edema in cfa-only rats (p<0.001). we observed a decreased inflammatory score in the thymol and carvacrol-treated rats. the evaluation of the tissue and serum inflammatory cytokine levels showed that both components decreased tumor necrosis factor (tnf)-α levels (p<0.05). thymol and carvacrol reduced interleukin (il)-1β serum and tissue levels, respectively. these components reduced tissue levels of il-17 from 148.4±13.4pg/ml in cfa-only rats to 90.1±18.9pg/ml (thymol) and 82.3±9.2pg/ml (carvacrol). both components decreased serum il-17 levels in rats (p<0.05). in comparison, the anti-inflammatory drug, indomethacin, reduced the inflammatory score and decreased tissue tnf-α and il-1β levels but did not affect il-17 production. conclusion: carvacrol and thymol could relieve inflammation symptoms possibly by downregulating serum and tissue il-17 expression in addition to key pro-inflammatory cytokines, tnfα and il-1β.