Genases (and other inflammatory mediators) [36]. This hypothesis is in accordance with
Genases (and other inflammatory mediators) [36]. This hypothesis is in accordance with those of Adeyemi et al. [37] and Zhang et al. [38], who have postulated that acetic acid-induced writhing is a highly sensitive and useful test for analgesic drug development, especially peripherally acting analgesics. Acetic acid induces pain by liberating endogenous substances (bradykinin, serotonin,histamine, substance P) [39], which in turn excite the pain nerve endings. In our observation, aqueous, methanolic, ethyl acetate and TOF-enriched extracts significantly (P < 0.001) reduced the abdominal constriction response induced by the acetic acid in a dose-dependent manner. TOF-enriched extract exhibited the most analgesic potency, whereas methanolic extract showed the weakest one. This result could be explained by the presence of active compounds diluted and/or masked by various components in the methanolic extract and which are more accessible and/or more concentrated in the TOFenriched extract. Besides, this test is useful for the evaluation of mild analgesic non steroidal, anti-inflammatory compounds [40,41]. This suggests a peripherally induced mechanism of the analgesic action for Cyperus rotundus extracts [42]. Therefore, one possible mechanism of the analgesic activity by C. rotundus extracts could be due to the blockage of the effect, or the release of endogenous substances (arachidonic acid metabolites) that excite pain nerve endings by the pharmacologically active principles of C. rotundus extracts. From a mechanistic point of view, the lack of specificity in acetic acid-induced writhing test suggests the involvement of different nociceptive mechanisms in the reduction of muscular constriction, such as sympathetic system, through the release of biogenic amines, cyclooxygenases and their metabolites inhibition, and through opioids receptors mechanisms [43]. In evaluating the anti-inflammatory effect, it is important to estimate the activities of the extracts in the acute phase as well as in the chronic phase of inflammation. Xylene-induced ear oedema in mice was selected to evaluate acute anti-inflammatory activity and is a good in vivo PubMed ID:https://www.ncbi.nlm.nih.gov/pubmed/25636517 test useful for evaluating lipoxygenase inhibitors and partially associated with substance P [44]. The AG-490MedChemExpress AG-490 results in Table 3 showed that the different extracts of C. rotundus caused significant inhibition of oedema as compared to the control group. These results may suggest that the plant extracts exert significant antiinflammatory activity, especially in the acute inflammatory response. The suppression of this response is aSoumaya et al. BMC Complementary and Alternative Medicine 2013, 13:28 http://www.biomedcentral.com/1472-6882/13/Page 8 ofFigure 2 PubMed ID:https://www.ncbi.nlm.nih.gov/pubmed/27741243 Effects of different extracts from Cyperus rotundus on in vitro proliferation response of splenocytes: (A) Cells were incubated with extract without mitogens, (B) cells were treated with extracts in the presence of 5 g/ml lectin, and (C) Cells were treated with extracts in the presence of 5 g/ml LPS. Cell proliferation was assessed by the MTT test. The data plotted represent average ?standard deviation of triplicates. Values in each line with asterisks (*) are significantly different (P<0.05).Soumaya et al. BMC Complementary and Alternative Medicine 2013, 13:28 http://www.biomedcentral.com/1472-6882/13/Page 9 oflikely indication of the antiphlogistic effect [45]. The topical anti-inflammatory effect suggests that constituents of the extract may relieve rheumatis.