BACKGROUND

Ageratum conyzoides Linn (Asteraceae), a tropical plant that is very common in West Africa and some parts of Asia and South America, has been used to treat inflammatory disorders. In Brazil, teas made from A. conyzoides L. are used as anti-inflammatory, analgesic and anti-diarrheic agents. Therefore, it is necessary to study the mechanism of anti-inflammatory action of A. conyzoides L. to support its medicinal use for treating inflammatory conditions. These studies will also support the development of effective pharmacological agents with potent anti-inflammatory properties.

OBJECTIVE

To evaluate the anti-inflammatory effects of the crude extract (CE), its derived fractions: ethanol (EtOH-F), hexane (HEX-F), ethyl acetate (EtOAc-F) and dichloromethane (DCM-F) and isolated compounds, such as 5'-methoxy nobiletin (MeONOB), 1,2-benzopyrone and eupalestin, which are obtained from the aerial parts of A. conyzoides L.

METHODS

These evaluations were performed using an animal model of inflammation induced by carrageenan. The following inflammatory parameters were analysed: leukocyte influx, protein concentration of the exudate, myeloperoxidase (MPO), adenosine deaminase (ADA) and nitric oxide metabolites (NOx) concentrations, interleukin 10 (IL-10), interleukin 17A (IL-17A), interleukin 6 (IL-6), tumor necrosis factor (TNF), interferon gamma (IFN-γ) and phosphorylation of p65 subunit of NF-κB (p-p65 NF-κB), p38 mitogen-activated protein kinases (p-p38 MAPK) were also analysed.

RESULTS

CE, its EtOH-F, HEX-F, EtOAc-F and DCM-F and the isolated compounds, including MeONOB, 1,2-benzopyrone and eupalestin, significantly reduced leukocyte influx, protein concentration of the exudate, MPO, ADA, and NOx concentrations (p<0.05). CE, EtOH-F and isolated compounds significantly reduced IL-17A, IL-6, TNF and IFN-γ levels (p<0.05). CE, EtOH-F and isolated compound 1,2-benzopyrone also increased IL-10 levels (p<0.05). Isolated compounds, MeONOB, 1,2-benzopyrone and eupalestin, reduced p-p65 NF-κB and p-p38 MAPK (p<0.01).

CONCLUSIONS

This study demonstrates that A. conyzoides L. exerts its important anti-inflammatory properties by inhibiting leukocyte influx and protein concentration of the exudate, as well as reducing the levels of several pro-inflammatory mediators. The anti-inflammatory action of A. conyzoides L. may be because of the inhibition of p65 NF-κB and MAPK activation by the isolated compounds.