This study was carried out to investigate the antimelanogenic effects of a Polygonum tinctorium flower extract obtained using red nuruk, a traditional Jeju barley-based fermentation starter. We also studied the mechanism of action of the P. tinctorium fermented flower extract (PTFFE) in mouse melanoma cells (B16F10). Cells were treated with various concentrations (62.5, 125 and 250 μg/mL) of PTFFE and the results showed that PTFFE significantly decreased the melanin content and tyrosinase activity without being cytotoxic. In addition, PTFFE strongly inhibited the expression of tyrosinase and tyrosinase-related protein 2 by decreasing the expression of the microphthalmia-associated transcription factor, as shown by a western blot assay. Furthermore, PTFFE inhibited melanogenesis via upregulation of the phosphorylation of extracellular signal-regulated kinase (ERK) and protein kinase B, also known as AKT. We also used inhibitors such as PD98059 (a specific ERK inhibitor) or LY294002 (an AKT inhibitor) to determine whether the signaling pathways are involved. High-performance liquid chromatography fingerprinting showed the presence of a quercetin glucoside (isoquercitrin) and quercetin in PTFFE. To test the potential for PTFFE application as a cosmetic material, we also performed a primary skin irritation test on human skin. In this assay, PTFFE did not induce any adverse reactions at the treatment dose. Based on these results, we suggest that PTFFE may be considered a potential antimelanogenesis candidate for topical applications.
In this study, the anti-inflammatory effects of nonyl 8-acetoxy-6-methyloctanoate (NAMO), isolated from the cultured marine diatom, Phaeodactylum tricornutum Bohlin, against LPS-induced RAW 264.7 macrophages were evaluated. NAMO has indicated the strongest inhibitory effects against nitric oxide (NO) and prostaglandin E 2 (PGE 2 ) production, dosedependently, on lipopolysaccharide (LPS)-induced RAW 264.7 cells. The 50% NO production inhibitory concentration (IC 50 ) of NAMO was 24.8 µM with the least cytotoxic effect in both LDH and MTT assays. Inflammatory stimulators such as LPS, which induce cytokines in the process of macrophage activation and mediate tissue response in different phases of inflammation, were studied. NAMO showed significant and strong suppression of pro-inflammatory cytokine and interleukin-1β (IL-1β) production, but no significant inhibitory effect on the production of cytokines including tumor necrosis factor-α (THF-α) and interleukin-6 (IL-6) at the tested concentrations against LPS treatment on RAW macrophages. Western blot analysis was carried out to determine the protein expressions of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) proteins which mediate the suppression effect of NAMO on NO and PGE 2 production. The Western blot assay confirmed the suppression of iNOS and COX-2 protein expressions against LPS-stimulated RAW264.7 cells. Collectively, NAMO isolated from the cultured marine diatom, P. tricornutum exhibited a profound anti-inflammatory effect in vitro, suggesting that the compound might have a beneficial effect during the treatment of inflammatory diseases and can be used in functional food applications.
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