Fermented dried <i>Citrus unshiu</i> peel extracts exert anti-inflammatory activities in LPS-induced RAW264.7 macrophages and improve skin moisturizing efficacy in immortalized human HaCaT keratinocytes

Abstract

<b>Context:</b> <i>Citrus unshiu</i> Markovich (Rutaceae) peel is known to contain high concentrations of flavonoids and exerts pharmacological effects on antioxidant, anti-inflammation, allergies, diabetes and viral infections. <b>Objective:</b> Very little is known about potential activity of fermented dried <i>Citrus unshiu</i> peel extracts (FCU) using <i>Bacillus subtilis</i>, as well as its mechanism of action. We investigated the effects of FCU on the anti-inflammatory activities in murine macrophages and moisturizing effects in human keratinocytes. <b>Materials and methods:</b> We isolated the <i>Bacillus subtilis</i> from Cheonggukjang and FCU using these <i>Bacillus subtilis</i> to prepare samples. The cells were pre-treated with various extracts for 2 h and then induced with LPS for 22 h. We determined the NO assay, TNF-α, IL-6 and PGE₂ in RAW 264.7 ells. The expression of SPT and Filaggrin by FCU treatment was measured in HaCaT cells. <b>Result:</b> We found that two types of FCU highly suppressed LPS-induced nitric oxide (NO) without exerting cytotoxic effects on RAW 264.7 cells (21.9 and 15.4% reduction). FCU inhibited the expression of LPS-induced iNOS and COX-2 proteins and their mRNAs in a concentration-dependent manner. TNF-α (59 and 30.9% reduction), IL-6 (39.1 and 65.6% reduction), and PGE₂ secretion (78.6 and 82.5% reduction) were suppressed by FCU in LPS-stimulated macrophages. Furthermore, FCU can induce the production of hyaluronic acid (38 and 38.9% induction) and expression of Filaggrin and SPT in HaCaT keratinocyte cells. <b>Discussion and conclusion:</b> FCU potentially inhibits inflammation, improves skin moisturizing efficacy, and it may be a therapeutic candidate for the treatment of inflammation and dry skin.