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Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has made significant impacts on global public health, including the development of several skin diseases that have arisen primarily as a result of the pandemic. Owing to the widespread expansion of coronavirus disease 19 (COVID-19), the development of effective treatments for these skin diseases is drawing attention as an important social issue. For many centuries, ginseng and its major active ingredients, ginsenosides and saponins, have been widely regarded as herbal medicines. Further, the anti-viral action of ginseng suggests its potential effectiveness as a therapeutic agent against COVID-19. Thus, the aim of this review was to examine the association of skin lesions with COVID-19 and the effect of ginseng as a therapeutic agent to treat skin diseases induced by COVID-19 infection. We classified COVID-19-related skin disorders into three categories: caused by inflammatory, immune, and complex (both inflammatory and immune) responses and evaluated the evidence for ginseng as a treatment for each category. This review offers comprehensive evidence on the improvement of skin disorders induced by SARS-CoV-2 infection using ginseng and its active constituents.

Olfactory receptors (ORs), which belong to the G-protein-coupled receptor family, have been widely studied as ectopically expressed receptors in various human tissues, including the skin. However, the physiological functions of only a few OR types have been elucidated in skin cells. All-trans retinoic acid (ATRA) is a well-known medication for various skin diseases. However, many studies have shown that ATRA can have adverse effects, resulting from the suppression of cell proliferation. Here, we investigated the involvement of OR7A17 in the ATRA-induced suppression of human keratinocyte (HaCaT) proliferation. We demonstrated that OR7A17 is expressed in HaCaT keratinocytes, and its expression was downregulated by ATRA. The ATRA-induced downregulation of OR7A17 was attenuated via RAR α or RAR γ antagonist treatment, indicating that the effects of ATRA on OR7A17 expression were mediated through nuclear retinoic acid receptor signaling. Moreover, we found that the overexpression of OR7A17 induced the proliferation of HaCaT cells while counteracting the antiproliferative effect of ATRA. Mechanistically, OR7A17 overexpression reversed the ATRA-induced attenuation of Ca2+ entry. Our findings indicated that ATRA suppresses cell proliferation through the downregulation of OR7A17 via RAR α- and γ-mediated retinoid signaling. Taken together, OR7A17 is a potential therapeutic target for ameliorating the anti-proliferative effects of ATRA.

Olfactory receptors (ORs), which belong to the G-protein-coupled receptor family, have been widely studied as ectopically expressed receptors in various human tissues, including the skin. However, the physiological functions of only a few OR types have been elucidated in skin cells. All-trans retinoic acid (ATRA) is a well-known medication for various skin diseases. However, many studies have shown that ATRA can have adverse effects, resulting from the suppression of cell proliferation. Here, we investigated the involvement of OR7A17 in the ATRA-induced suppression of human keratinocyte (HaCaT) proliferation. We demonstrated that OR7A17 is expressed in HaCaT keratinocytes, and its expression was downregulated by ATRA. The ATRA-induced downregulation of OR7A17 was attenuated via RAR α or RAR γ antagonist treatment, indicating that the effects of ATRA on OR7A17 expression were mediated through nuclear retinoic acid receptor signaling. Moreover, we found that the overexpression of OR7A17 induced the proliferation of HaCaT cells while counteracting the antiproliferative effect of ATRA. Mechanistically, OR7A17 overexpression reversed the ATRA-induced attenuation of Ca2+ entry. Our findings indicated that ATRA suppresses cell proliferation through the downregulation of OR7A17 via RAR α- and γ-mediated retinoid signaling. Taken together, OR7A17 is a potential therapeutic target for ameliorating the anti-proliferative effects of ATRA.

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.