Anti-Inflammatory Activity of Dichondra micrantha Extract and Its Potential as a Functional Cosmetic Ingredient

This study aimed to evaluate the anti-inflammatory activity of <i>Dichondra micrantha</i> ethanol extract (DM-EE) and to elucidate its regulatory effects on the NF-κB and AP-1 signaling pathways in vitro. Ethanolic extract of <i>Dichondra micrantha</i> was prepared and tested in RAW264.7 macrophages. Cell viability was assessed using the MTT assay, and nitric oxide (NO) production was measured in cells stimulated with lipopolysaccharide (LPS), polyinosinic–polycytidylic acid [Poly I:C], and Pam3CSK4. In addition, AP-1 and NF-κB luciferase reporter assays, RT-PCR analysis of inflammatory mediators, and Western blot analysis of phosphorylated signaling proteins were performed. DM-EE exhibited no significant cytotoxicity within the tested concentration range. It significantly inhibited LPS-, Poly I:C-, and Pam3CSK4-induced NO production in a concentration-dependent manner, with the strongest inhibitory effect observed at 200 μg/mL. Moreover, DM-EE suppressed LPS- and Poly I:C-induced AP-1 and NF-κB transcriptional activity. RT-PCR analysis revealed that DM-EE downregulated the mRNA expression of inflammatory mediators, including iNOS, COX-2, and IL-1β, in LPS-stimulated RAW264.7 cells. Consistently, Western blot analysis showed that DM-EE reduced the phosphorylation levels of p65 and c-Jun, indicating inhibition of NF-κB and AP-1 activation. These findings demonstrate that DM-EE exerts significant anti-inflammatory effects by attenuating macrophage-mediated inflammatory responses through suppression of the NF-κB and AP-1 signaling pathways. Therefore, <i>Dichondra micrantha</i> extract showed potential as a natural bioactive material with anti-inflammatory properties under in vitro conditions.