RESUMO
Bixin is the main natural apocarotenoid extracted from the seeds of Bixa orellana, widely used as a cosmetic and textile colorant. Despite the description of several pharmacological properties of B. orellana extracts, little has been studied regarding the pharmacological properties of bixin. Then we aimed to investigate the potential anti-inflammatory and antinociceptive effect of bixin in preclinical models of inflammation and acute pain. The anti-inflammatory activity of bixin (15 or 30 mg/kg, orally) was determined using carrageenan-induced paw edema and the myeloperoxidase (MPO) activity in male Wistar rats. The antinociceptive effect of bixin was assessed in the formalin and hot plate tests in rats (at same doses) and in the acetic acid-induced writhing test in Swiss albino male mice (at doses of 27 or 53 mg/kg). General locomotor activity was evaluated in the open field test. Only the higher dose of bixin significantly decreased the carrageenan-induced paw edema and the MPO activity and increased the latency time in the hot plate. Both doses of bixin significantly reduced the number of flinches in both phases of the formalin test and the number of acetic acid-induced writhings without changing the locomotor performance in the open field test. This study validates the use of bixin as an anti-inflammatory trough mechanism related to the reduction of neutrophil migration. Furthermore, this is the first report showing the antinociceptive property of bixin, which does not appear to be related to the sedative effect. Further studies are necessary to characterize the mechanisms involved in these effects.