Anti-nociceptive and anti-inflammatory effects of Croton crassifolius ethanol extract.

ETHNOPHARMACOLOGICAL RELEVANCE: Croton crassifolius has been used to treat snake bites, stomach ache, sternalgia, joint pain, as well as pharyngitis, jaundice, and rheumatoid arthritis in traditional Chinese medicine. However, there is no scientific evidence which supports the use in the literature.

AIM OF THE STUDY: To investigate the anti-nociceptive and anti-inflammatory effects of ethanol extract of C. crassifolius.

MATERIALS AND METHODS: Anti-nociceptive actions of C. crassifolius were assessed in mice using the hot-plate test, acetic acid-induced writhing test, and formalin test. Anti-inflammatory effects of C. crassifolius were determined in three animal models: acetic acid-induced capillary permeability accentuation in mice, carrageenan-induced edema of the hind paw in rats, and cotton pellet-induced granuloma formation in rats.

RESULTS: Ethanol extract of C. crassifolius showed no significant anti-nociceptive activity in the hot-plate test. However, extract at dosages of 45, 90 and 180 mg/kg significantly reduced acetic acid-induced writhing by 28.89% (P<0.05), 38.37% (P<0.05), and 56.53% (P<0.001), respectively. The extract also caused marked dose-related inhibition of formalin-induced pain in the second phase (P<0.05 for 45 mg/kg, P<0.001 for 90 and 180 mg/kg extract). C. crassifolius extract at dosages of 45, 90 and 180 mg/kg significantly reduced acetic acid-induced capillary permeability accentuation in mice by 26.18% (P<0.05), 65.70% (P<0.001), and 79.19% (P<0.001), and suppressed carrageenan-induced paw edema by 21.28% (P<0.05), 30.69% (P<0.01), and 49.17% (P<0.001) at 6 h after carrageenan injection, respectively. 180 mg/kg of the extract also showed significant activity against carrageenan-induced paw edema at 4 h. At 90 and 180 mg/kg, the extract inhibited cotton pellet-induced granuloma formation in rats.

CONCLUSIONS: These results collectively demonstrate that the ethanol extract of C. crassifolius possesses peripheral anti-nociceptive and anti-inflammatory effects, providing evidence to rationalize the traditional use of C. crassifolius for the treatment of pain and inflammation.