Anti-inflammatory And Analgesic Fraction Of The Miao’s Herb Oxalis Corniculata

Objective: To determine the anti-inflammatory and analgesic fraction of Oxalis corniculata and to chemically characterize the effective fraction.Methods: Water, 50% aqueous ethanol, 70% aqueous ethanol and 95% aqueous ethanol were used in the extraction for solvent selection. The anti-inflammatory activity and analgesic activity of the obtained extracts were assessed by the acetic acid-induced celiac capillary permeability and the acetic acid-induced writhing tests in mice. Combined analysis of the above biological activity and HPLC-based chemical information was used for selection of the extraction solvent. The possible indicators concerned with the anti-inflammatory and analgesic activities were evaluated by testing the serum superoxide dismutase(SOD) and malondiadehyde(MDA) levels in mice. Four fractions were prepared successively from the 70%aqueous ethanol extract by petroleum ether, chloroform, ethyl acetate, n-butanol. The effective fraction were then determined through anti-inflammatory and analgesic activities evaluation. PGE2 assay was conducted to see whether the anti-inflammatory and analgesic activities of effective fraction were correlated to the PGE signaling pathway. The chemical components of the effective fraction were analyzed by UHPLC-Q-TOF-MS and UPLC-PDA-MS. Results: The 70% aqueous ethanol was adopted for extraction as its extract gave more abundant chemical information, and more remarkably suppressed the increase of peritoneal capillary permeability, and reduced the times of writhing. The extract significantly increased the serum SOD level and reduced MDA level. The chemical information of ethyl acetate and n-butanol fractions are much richer, but many common peaks exist in both fractions.The serum PGE2 levels of mice after oral administration of a combination of the two fractions were significantly reduced in a dose dependent manner. UHPLC-Q-TOF-MS and UPLC-PDA-MS methods provide formulas, UV absorption wavelength, and MS fragmentation ions for 20 main peaks of the combined active fraction. Among them three chemical components were structurally identified by standards. Chemical analysis showed that effective fraction contain a variety of acyl quinic acids and phenolic compounds such as flavonoids. Conclusion: Anti-inflammatory and analgesic effects of 70% aqueous ethanol extract was better; The fraction that ethyl acetate fraction combined n-butanol fraction is the anti-inflammatory and analgesic fraction. The anti-inflammatory and analgesic effects of the active fraction might be attributed to antioxidation and PGE2 production inhibition. Phenolic compounds,particularly flavonoids glycosides including C-glycosides and O-glycosides are the main chemical components of the active fraction, which might be responsible for the anti-inflammatory and analgesic effects of the Oxalis corniculata. The present study provides the experimental basis for the research and development of Oxalis corniculata and its active substances.