Investigation of antinociceptive activity of methanolic extract of Persicaria orientalis leaves in rodents.

BACKGROUND: This study aims to evaluate the scientific basis of traditional application of Persicaria orientalis for reducing pain and inflammation. METHODS: An in vitro method was performed to investigate the presence of the anti-inflammatory activity of methanolic crude extract of P. orientalis. In addition, an in vivo study was conducted in which the hot-plate and tail immersion methods were applied to explore the acute effect of P. orientalis on analgesia. The potency to inhibit chronic inflammation in mice was justified by the carrageenan-induced paw edema and formalin-induced edema methods. For all in vivo testing in animal models (albino mice and rats), plant extract was given via the oral route at doses of 250 mg/kg and 500 mg/kg. RESULTS: The methanolic extract of P. orientalis produced a significant (p<0.001) inhibition of analgesia with a prolongation of pain response time by 61.80% at 500 mg/kg. The extract also exhibited a potential anti-inflammatory (56.99%) effect, which was also statistically significant (p<0.001). The present study suggests that the methanolic extract of P. orientalis has potential anti-inflammatory as well as analgesic activity and this extract is effective in the treatment of both acute and chronic pain. CONCLUSIONS: Our current study revealed pharmacological properties of the methanolic extract of P. orientalis and also gave a solid scientific platform against its traditional use. The protecting ability of P. orientalis against inflammatory stimuli may be due to phenolic or flavonoid compounds which we have found through phytochemical analysis.