ABSTRACT
Calophyllum brasiliense is used as anti-inflammatory and analgesic in Brazilian traditional medicine. Thus, the main purpose of this study is to evaluate the antinociceptive effect of the chloroform fraction of C. brasiliense (CFCB) roots and to investigate its main mechanism of action. The antinociceptive effect of CFCB was evaluated in mice using acetic acid-induced writhing, formalin-induced paw licking, and hot-plate tests and capsaicin- and glutamate-induced nociception. Brasiliensic acid and 1,2-dimethoxyxanthone were isolated and evaluated in writhing test. The amount of 1,2-dimethoxyxanthone was determined in the fraction by UPLC-DAD. CFCB inhibited abdominal constrictions induced by acetic acid up to 97%, with an ID50 of 9.4 mg/kg (i.p.) and 131.8 mg/kg (p.o.). In the formalin test, CFCB impaired paw licking with an ID50 of 26.3 mg/kg for the first phase and 27.5 mg/kg for the second phase (i.p.). The painful response evoked by capsaicin and glutamate was significantly reduced (ID50 26.7 and 47.9 mg/kg, i.p.). The latency time was increased up to 76% at 60 mg/kg (i.p.) in the hot-plate test. 1,2-Dimethoxyxanthone was almost three times more potent (ID50 27.6 µmol/kg, i.p.) than brasiliensic acid (72.0 µmol/kg) in acetic acid-induced writhing test. The amount of the xanthone was estimated as 92.5 mg/g in the extract. CFCB inhibited the nociceptive response associated to several agents. TRPV1 channels play an important role in the mechanism of action of the fraction. In addition, 1,2-dimethoxyxanthone largely contributes to the antinociceptive effect of CFCB.
