Analgesic and anti-inflammatory activities of Torenia concolor Lindley var. formosana Yamazaki and betulin in mice.

The present study was intended to examine the analgesic effect of the 70% methanol extract of Torenia concolor Lindley var. formosana Yamazaki (TC(MeOH)) and betulin using models of acetic acid-induced writhing response and formalin test. In addition, we investigated the anti-inflammatory effect of TC(MeOH) and betulin using model of lambda-carrageenan-induced paw edema. We observed the activities of antioxidant enzymes (SOD, GPx and GR) in the liver and the levels of malondialdehyde (MDA) and nitric oxide (NO) in the edema paw. The results showed that TC(MeOH) (1.0 and 2.0 g/kg) and betulin (30 and 90 mg/kg), significantly inhibited the acetic acid-induced writhing response. TC(MeOH) (2.0 g/kg) and betulin (30 and 90 mg/kg) significantly inhibited formalin-induced licking time during both the early and late phases. TC(MeOH) (0.5, 1.0 and 2.0 g/kg) and betulin (30 and 90 mg/kg) also significantly decreased the paw edema at the 4th hour after lambda-carrageenan injection. Furthermore, TC(MeOH) and betulin treatment also significantly increased the activities of SOD, GR and GPx in the liver while decreasing the level of MDA in the edema paw. Finally, betulin (30 and 90 mg/kg) also caused considerable reduction of NO level in the edema paw. Taken together, the present results indicated that TC(MeOH) and betulin possessed analgesic and anti-inflammatory effects. The anti-inflammatory mechanism of TC(MeOH) and betulin may be related to decreasing the levels of MDA and NO in the edema paw by increasing the activities of antioxidant enzymes in the liver.