Yellow Chaste Weed and Its Components, Apigenin and Galangin, Affect Proliferation and Oxidative Stress in Blue Light-Irradiated HaCaT Cells.

While harmful effects of blue light on skin cells have been recently reported, there are few studies regarding natural products that alleviate its negative effects. Therefore, we investigated ameliorating effects of yellow chaste weed (YCW) (Helichrysum arenarium) extract and its components, apigenin and galangin, on blue light-irradiated HaCaT cells. In this study, we found that YCW extract improved the reduced proliferation of HaCaT cells induced by blue light-irradiation and reduced blue light-induced production of reactive oxygen species (ROS) levels. We also found that apigenin and galangin, the main components of YCW extract, showed the same activities as YCW extract. In experiments examining molecular mechanisms of YCW extract and its components such as apigenin and galangin, they all reduced expression of transient receptor potential vanilloid member 1 (TRPV1), its phosphorylation, and calcium ion (Ca2+) influx induced by blue light irradiation. In addition, apigenin and galangin regulated phosphorylation of mitogen-activated protein kinases (MAPKs). They also reduced phosphorylation of mammalian sterile 20-like kinase-1/2 (MST-1/2), inducing phosphorylation of Akt (protein kinase B), one downstream molecule of MST-1/2. Moreover, apigenin and galangin promoted translocation of Forkhead box O3 (FoxO3a) from the nucleus to the cytosol by phosphorylating FoxO3a. Besides, apigenin and galangin interrupted blue light influences on expression of nuclear and secretory clusterin. Namely, they attenuated both upregulation of nuclear clusterin and downregulation of secretory clusterin induced by blue light irradiation. We also found that they downregulated apoptotic protein Bcl-2 associated X protein (Bax) and conversely upregulated anti-apoptotic protein B-cell lymphoma 2 (Bcl-2). Collectively, these findings indicate that YCW extract and its components, apigenin and galangin, antagonize the blue light-induced damage to the keratinocytes by regulating TRPV1/clusterin/FoxO3a and MAPK signaling.

Effect of Camellia japonica oil on human type I procollagen production and skin barrier function.

Type I collagen is the primary component of the skin dermis. Both the quantity and quality of extracellular collagen are primarily related to skin ageing. In this study, we investigated the possibility that Camellia japonica oil (CJ oil) may be introduced as an anit-wrinkle agent. As a first step to this end, human COL1A2 promoter luciferase assay was performed in human dermal fibroblast cells. CJ oil was determined to activate human COL1A2 promoter in a concentration-dependent manner. In consistency with this result, while matrix metalloproteinase (MMP)-1 activity was inhibited by CJ oil, human type I procollagen synthesis was also induced by CJ oil. These results suggest the possibility that CJ oil may be involved in the skin ageing. For the evaluation of CJ oil's safety and efficiency on human skin, human skin primary irritation test and trans-epidermal water loss (TEWL) were performed. Transepidermal water loss (TEWL) was measured before treatment then, 1h and 2h after treatment; the forearm site was selected to measure TEWL. Also, a human skin primary irritation test was performed on the normal skin (upper back) in 30 volunteers to see if a certain material included in CJ oil has irritation or sensitization potential. In these assays, CJ oil reduced trans-epidermal water loss (TEWL) and did not induce any adverse reactions. Therefore, based on these results, we suggest the possibility that CJ oil may be considered as possible wrinkle-reducing candidates for topical application.