Anethole reduces inflammation and joint damage in rats with adjuvant-induced arthritis.

AIM: This study evaluated whether anethole attenuates the inflammatory response and joint damage in a model of adjuvant-induced arthritis (AIA) in rats. METHODS: The animals were treated with 62.5-, 125-, or 250-mg/kg anethole daily for 21 days after AIA and necropsied on days 14 and 21 to evaluate the number of serum and synovial leukocytes (total and differential), serum cytokines (IL-2, IL-6, IL-12, IL-17, and TNF-α), and nitric oxide concentrations. Morphologic changes in the cartilage and bone of the femorotibial articulation in both left paw and right paw were studied in hematoxylin/eosin and Sirius Red-hematoxylin sections. RESULTS: Different doses of anethole suppressed paw swelling and the number of serum and synovial leukocytes. However, 250 mg/kg of anethole more effectively controlled local and systemic inflammation. Histological evaluation revealed significant prevention of cartilage damage and inflammatory infiltrate scores. Morphometric analysis showed pannus formation, the thickness of the articular cartilage, and bone resorption lower in the anethole-treated AIA group compared to untreated AIA group on both days 14 and 21. These significant anti-inflammatory effects in the anethole-treated AIA group were associated with downregulation of cytokines and nitric oxide levels. CONCLUSION: Therefore, anethole may be a useful intervention to treat inflammatory arthritis.

Fish Oil and Adjuvant-Induced Arthritis: Inhibitory Effect on Leukocyte Recruitment.

Fish oil, a rich source of n-3 fatty acids, has been studied for its beneficial effects in many diseases. Recent studies have shown the robust anti-inflammatory activity of fish oil (FO), when administered orally to rats, in models of acute inflammation. Herein, we investigated if treatment with fish oil preparation (FOP) could interfere with the recruitment of leukocytes into the joint cavity of arthritic rats. We also evaluated the effect of treatment on rolling behavior and leukocyte adhesion in vivo and on leukocyte chemotaxis in vitro. Treatment with FOP (75, 150, and 300 mg/kg) initiated on the day of induction of arthritis (day 0) and maintained for 21 days reduced the total number of leukocytes recruited into the joint cavity, the number of rolling and adhered leukocytes in arthritic rats, and leukocyte migration in response to stimulation with N-formyl-methionyl-leucyl-phenylalanine (fMLP) and leukotriene B4 (LTB4). Together, our data provide evidence that FOP plays an important inhibitory role in the recruitment of leukocytes into the joint cavity of arthritic rats.

Anethole and eugenol reduce in vitro and in vivo leukocyte migration induced by fMLP, LTB4, and carrageenan.

The aim of this study was to investigate the effect of anethole (AN) and eugenol (EUG) on leukocyte migration using in vitro chemotaxis and in situ microcirculation assays. BALB/c mice were used for the in vitro chemotaxis assay, and Wistar rats for the in situ microcirculation assay. We evaluated (a) the in vitro leukocyte migration in response to chemotactic factors (formyl-methionyl-leucyl-phenylalanine [fMLP] and leukotriene B4 [LTB4]) and (b) the rolling, adhesion, and migration of leukocytes induced by an injection of carrageenan (100 µg/cavity) into the scrotum of the animal. In the in vitro chemotaxis assay, AN and EUG at doses of 1, 3, 9, and 27 µg/ml significantly inhibited leukocyte migration when stimulated by the chemotactic agents fMLP and LTB4. In the in situ microcirculation assay, AN at doses of 125 and 250 mg/kg and EUG at a dose of 250 mg/kg significantly decreased the number of leukocytes that rolled, adhered, and migrated to perivascular tissue. The results indicate that AN and EUG exert inhibitory effects on leukocyte migration, highlighting their possible use to diminish excessive leukocyte migration in the inflammatory process.

Evaluation of Anti-Inflammatory Activity of Citrus latifolia Tanaka Essential Oil and Limonene in Experimental Mouse Models.

The genus Citrus (Rutaceae) includes several species of plants that produce some of the most cultivated fruits in the world, providing an appreciable content of essential oil. In folk medicine, they are used as a cholagogue, antipyretic, anti-inflammatory, sedative, and antitoxic effects. Lemon essential oil has been used since ancient times for its antiseptic, carminative, diuretic, and eupeptic effects. In this study, we investigated the anti-inflammatory activity of Citrus latifolia Tanaka essential oil (CLEO) and its main constituent LIM. In the cell viability assay, CLEO and LIM (3, 10, 30, and 90 µ g/mL) had low cytotoxicity. In zymosan-induced peritonitis, LIM (500 mg/kg) decreased the infiltration of peritoneal exudate leukocytes and decreased the number of polymorphonuclear leukocytes. In vitro chemotaxis revealed that CLEO and LIM (1, 3, and 10 µg/mL) promoted a significant reduction of neutrophil migration toward fMLP and LTB4. LIM (500 mg/kg) also reduced TNF- α levels but did not alter IL-10 levels in the peritoneal exudate. In conclusion, this study showed that LIM isolated from CLEO had potential anti-inflammatory effects, likely by inhibiting proinflammatory mediators present in inflammatory exudate and leukocyte chemotaxis.

Inhibitory effect of anethole in nonimmune acute inflammation.

Anethole [1-methoxy-4-(1-propenyl)benzene] occurs naturally as a major component of the essential oil of star anise (Illicium verum Hook.f., family Illiciaceae), comprising more than 90 % of its volatile components. Studies showed that this substance has antioxidant, antibacterial, antifungal, and anesthetic properties. In this study, the anti-inflammatory properties of anethole in animal models of nonimmune acute inflammation such as croton oil-induced ear edema and carrageenan-induced pleurisy were investigated. The investigated parameters were edema formation, leukocyte migration, and inflammatory mediators involved. Oral administration of anethole at a dose of 250 and 500 mg/kg reduced both the volume of pleural exudates and the number of migrated leukocytes. Levels of nitric oxide (NO) and prostaglandins (PGE2) in the inflammatory exudate were reduced by treatment with anethole, but levels of tumor necrosis factor-α and interleukin-1ß were not significantly altered. In ear edema, the oral treatment with anethole inhibited the formation of exudate and the activity of myeloperoxidase, but not after topical administration. These results suggest that the anethole may be effective in controlling some nonimmune acute inflammation-related disease, probably by an inhibitory action on production and/or release of PGE2 and NO.

Effects of Thymol and Carvacrol, Constituents of Thymus vulgaris L. Essential Oil, on the Inflammatory Response.

Thyme (Thymus vulgaris L., Lamiaceae) is an aromatic and medicinal plant that has been used in folk medicine, phytopharmaceutical preparations, food preservatives, and as an aromatic ingredient. The effect of Thymus vulgaris essential oil (TEO) and its isolated constituents thymol and cavacrol (CVL) were studied in the following experimental models: ear edema, carrageenan-induced pleurisy, and chemotaxis in vitro. In the pleurisy model, TEO, CVL, and thymol significantly inhibited inflammatory edema. However, only TEO and CVL inhibited leukocyte migration. In the in vitro chemotaxis experiment, CVL inhibited leukocyte migration, whereas thymol exerted a potent chemoattractant effect. In the ear edema model, CVL (10 mg/ear), applied topically, reduced edema formation, exerting a topical anti-inflammatory effect. Thymol did not reduce edema formation but rather presented an irritative response, probably dependent on histamine and prostanoid release. Our data suggest that the antiinflammatory effects of TEO and CVL are attributable to the inhibition of inflammatory edema and leukocyte migration.