Anti-nociceptive and anti-inflammatory effects of the methanolic extract of Opuntia humifusa stem

Objective: Opuntia humifusa (O. humifusa) Raf. has been used for the prevention and treatment of rheumatoid arthritis, inflammation, and cancer. Our study was designed to unveil the anti-nociceptive and anti-inflammatory effects of the methanolic extract of O. humifusa Raf stem (OHS). Material and Methods: The anti-nociceptive effect was measured by hot plate, acetic acid-induced writhing, and tail flick assays in mice and rats. Moreover, the anti-inflammatory effect was measured by vascular permeability and carrageenan and serotonin-induced paw edema tests in rats. Furthermore, anti-inflammatory effect was also measured using macrophage-like LPS-induced RAW 264.7 cells. Results: OHS extract inhibited acetic acid-induced writhing (p<0.0001), and delayed the reaction time of mice to the hot plate-induced thermal stimulation (p<0.0001) and tail flick tests (p<0.05). OHS extract attenuated the carrageenan and serotonin-induced paw edema in rats (p<0.001). Similarly, OHS extract significantly decreased Evans blue concentration in acetic acid induced vascular permeability test (p<0.0001), revealing its strong anti-inflammatory effect. Finally, among four different fractions of OHS extract, n-butanol fraction strongly decreased NO production (p<0.0001) and iNOS expression in LPS-induced RAW 264.7 cells. Conclusion: Our results suggest that the methanolic extract of O. humifusa stem can be used to develop a therapeutic or supportive drug and/or functional food against pain and inflammation related diseases. Keywords