Insights on the Anti-Inflammatory and Anti-Melanogenic Effects of 2'-Hydroxy-2,6'-dimethoxychalcone in RAW 264.7 and B16F10 Cells.

Chalcones are recognized for their diverse pharmacological properties, including anti-inflammatory and anti-melanogenic effects. However, studies on 2'-hydroxy-2-methoxychalcone derivatives remain limited. This study investigated the anti-inflammatory and melanin synthesis-inhibitory effects of three derivatives: 2'-hydroxy-2,4-dimethoxychalcone (2,4-DMC), 2'-hydroxy-2,5'-dimethoxychalcone (2,5'-DMC), and 2'-hydroxy-2,6'-dimethoxychalcone (2,6'-DMC). In lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages, 2,6'-DMC demonstrated a superior inhibition of nitric oxide (NO) production, pro-inflammatory cytokines, and the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) compared to the other derivatives. A mechanistic analysis revealed that 2,6'-DMC modulates the NF-κB and MAPK signaling pathways to attenuate inflammation. Additionally, 2,6'-DMC exhibited a significant inhibition of α-melanocyte-stimulating hormone (α-MSH)-induced melanin synthesis in B16F10 melanoma cells by downregulating tyrosinase, TRP-1, TRP-2, and MITF expression. This regulation was achieved through the suppression of the Wnt/β-catenin, PI3K/AKT, MAPK, and PKA/CREB pathways. Compared to 2,4-DMC and 2,5'-DMC, 2,6'-DMC's structural configuration, characterized by methoxy groups at the 2- and 6'-positions, contributed to its enhanced molecular stability and binding affinity, amplifying its inhibitory effects. A primary skin irritation test confirmed that 2,6'-DMC exhibited minimal irritation, demonstrating its safety for dermal applications. These findings suggest that 2,6'-DMC holds promise as a dual-function agent for managing inflammatory conditions and hyperpigmentation-related disorders.