The monoterpene position isomers estragole and anethole attenuates zymosan-induced arthritis in mice

Abstract

The isomers estragole (EST) and anethole (ANT) has been reported to present anti-inflammatory activity in different experimental models of inflammation. This study investigated the effects of EST and ANT on leukocytes migration into the knee joint, the activity of myeloperoxidase (MPO), the levels of nitric oxide (NO), cytokines and the oxidative status in the joint tissue. EST and ANT equally inhibit the zymosan-induced neutrophils influx and the levels of NO and MPO activity into the joint. EST reduced the levels of TNF-α, IL-1β, IL-6 at the dose of 250 mg/kg and500 mg/kg. Only 500 mg/kg ANT reduced in minor extension the levels of TNF-α and IL-6. In contrast, the IL-10 joint levels were increased in mice treated with both ANT and EST. In addition, both EST and ANT reduced the zymosan-induced oxidative stress in the joint; however, ANT was more potent than EST to this respect. The latter could be attributed to an additional reactive species scavenging due to the double bond of the propenyl chain conjugated with the aromatic ring in ANT, but not present in EST. This same structural difference should be responsible by the distinct modulation of zymosan-induced cytokine production in the joint.