Antinociceptive and anti-inflammatory activities of standardized extract of polymethoxyflavones from Ageratum conyzoides

Ethnopharmacological relevance: Ageratum conyzoides L. is a plant widely used in traditional medicine in tropical and subtropical regions of the world due to its anti-inflammatory, antinociceptive and Antibacterial properties.

Aim of the study: To characterize the standardized extract of polymethoxyflavones (SEPAc) from the plant and evaluate its antinociceptive and anti-inflammatory effects.

Materials and methods: The SEPAc purified from the ethanol extract of the plant leaves was characterized by high resolution mass spectrometry and the methoxyflavones were quantified by a validated UPLC-PDA method. The antinociceptive and anti-inflammatory activities of the SEPAc were evaluated after oral administration on the acute nocifensive behavior of mice induced by formalin, prostaglandin E2 (PGE2) and proinflammatory cytokines (interleukin-1beta (IL-1β)) and tumor necrosis factor-alpha (TNF-α) in mice.

Results: Qualitative analyses revealed the presence of seven methoxyflavones in the SEPAc, also a simple UPLC-PDA method was developed and validated for the quantification of 5,6,7,3',4',5'-hexametoxyflavone; nobiletin; 5'-methoxynobiletin and eupalestin, major compounds in the extract. The SEPAc exhibited antinociceptive and anti-inflammatory activities in both formalin phases, with significant inhibition of the paw edema formation and significant reduction of the nocifensive response induced by an intraplantar injection of PGE2 and intrathecal injection of interleukin-1β.

Conclusions: The SEPAc exhibited significant antinociceptive and anti-inflammatory effects. These results provided scientific suggestion of its potential as a source of new medicines to treat inflammatory diseases, such rheumatoid arthritis.

3′-Hydroxy-5,6,7,8,4′,5′-hexamethoxyflavone (PubChem CID: 44258654); 5,6,7,3′,4′,5′-Hexamethoxyflavone (PubChem CID: 185670); 5′-Methoxynobiletin (PubChem CID: 72815); Ageratum conyzoides; Anti-inflammatory; Antinociceptive; Eupalestin (PubChem CID: 331149); Linderoflavone B (PubChem CID: 97151); Methoxyflavones; Nobiletin (PubChem CID: 72344); Quercetin (PubChem CID: 5280343); Sinensetin (PubChem CID: 145659).