Psoriasis is a chronic inflammatory skin disease that causes erythema, scale, and invasion due to excessive proliferation of keratinocyte and vascular deformation of the upper part of the dermis. Recently, it has been reported that brazilin, an active compound of Caesalpinia sappan L., possesses anti-inflammatory activity in mouse macrophage. However, little is known about its effect or anti-inflammatory activity on psoriasis dermatitis. Thus, the objective of this study was to determine anti-inflammatory activity of brazilin in TNF-α-induced human keratinocyte (HaCaT) widely used as a model of psoriatic dermatitis. First, CCK-8 assay was performed to determine cytotoxicity of brazilin in HaCaT cells and cytotoxicity was not observed up to 7 μg/mL concentrations. Brazilin decreased mRNA expression levels of inflammatory cytokines such as IL-1α, IL-1β, IL-6, IL-8 and TNF-α in a concentration dependent manner. Brazilin also significantly reduced phosphorylation of I-κB, Akt, and MAPKs such as ERK, JNK, p38 and STAT3 in immortalized human keratinocytes (HaCaT) induced by TNF-α. In addition, inflammation causes the weakness of the skin barrier structure and increase cell permeability, stimulating serious problems in skin moisturizing. Thus, we observed changes of skin permeability in TNF-α induced inflammatory condition through transepithelial electrical resistance (TEER) assay. While TNF-α induced inflammation caused reduction of TEER value (ohm (Ω) × cm 2 ), it was recovered by treatment with brazilin in a concentration-dependent manner. These results strongly imply that brazilin can reinforce the skin barrier due to its anti-inflammatory activity. Therefore, brazilin could be a promising candidate for treating psoriasis dermatitis. which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.
Rebaudioside A is a natural sweetener isolated from Stevia rebaudiana Bertoni, one of the glycosides based on steviol. Recent studies have shown that rebaudioside A inhibits the inflammatory response by inhibiting cytokines secretion such as interleukin-1α/1β in activated RAW264.7 mouse macrophage cells by LPS. However, the inhibitory mechanism of inflammation by rebaudioside A in the presence of LPS has not been fully elucidated. Therefore, in this study, we tried to investigate the antiinflammatory activity of rebaudioside A at the protein level when RAW264.7 cells were stimulated by LPS. The inducible nitric oxide synthase protein expression level was reduced in the group treated with 250 μM rebaudioside A compared to the LPS-treated group. In addition, the mRNA expression level of NF-κB, which is a representative nuclear transcription factor by inflammatory signal, was also decreased as compared with that of LPS-treated group. In addition, NF-κB and inhibitor-κB (I-κB) complexes that are known to be dissociated by I-κB phosphorylation and ubiquitination were less phosphorylated than LPS treated group in the presence rebaudioside A. Finally, we could find that rebaudioside A was involved in the NF-κB pathway through reducing extracellular signal-regulated kinase1/2 phosphorylation in a concentration-dependent manner. These results suggest that rebaudioside A might suppress inflammatory reaction through MAPK and NF-κB regulation in LPS-stimulated RAW264.7.
Ligustrum lucidum Aiton is a flowering plant of the Oleaceae family, and its fruits have been traditionally used for skin nourishment and the treatment of skin diseases. However, the anti-inflammatory constituents for skin disease are not well-characterized. Phytochemical investigation of L. lucidum fruits resulted in the isolation of a new secoiridoid, secoligulene (1), together with (E)-3-(1-oxobut-2-en-2-yl)pentanedioic acid (2) and trans-(E)-3-(1-oxobut-2-en-2-yl)glutaric acid (3). Secoligulene (1) displayed the potent inhibitory effect on NO production with an IC50 value of 12.0 μg/mL. Secoligulene (1) also downregulated mRNA transcriptional levels of pro-inflammatory cytokines such as IL-1 α, IL-1β, IL-6 and COX-2 in LPS-stimulated RAW264.7 cells. Further investigation showed that secoligulene (1) inhibited the phosphorylation of IκB and JNK activated by LPS. In addition, secoligulene (1) downregulated the expression of chemokines such as CXCL8 and CCL20 in the TNF-α/IL-17/IFN-γ induced HaCaT psoriasis model. Taken together, these findings support the beneficial effects of L. lucidum and its constituents on inflammation-related skin diseases and can be further developed as therapeutic treatments for related diseases.
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