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Introduction
Human skin is divided into epidermal, dermal and fatty subcutaneous tissues. The epidermis, which is comprised mainly of keratinocytes, is classified into multiple layers, the stratum corneum, granular layer, spinous layer and basal layer, based on the differentiation stage of the keratinocytes (1). Keratinocytes are known to have an important role in inflammation (2). Indeed, many inflammation-related skin diseases, such as allergic contact dermatitis, psoriasis and atopic dermatitis, are highly associated with the function of keratinocytes and cytokines (3). Keratinocytes are also a major source of inflammatory mediators, including members of the tumor necrosis factor (TNF)-α and interleukin (IL) families (2). Overproduction of pro-inflammatory mediators may lead to an abnormal inflammatory response. For this reason, potential anti-inflammatory agents can be used to suppress pro-inflammatory mediators (4).
Multiple studies have discovered anti-inflammatory and wound healing activities in substances extracted from plants (5,6). The effects of Ashwagandha (Withania Somnifera) leaves and roots, one of the most popular herbal treatments in the traditional Ayurvedic medicine in India, are considered to include enhancements in physical strength, energy, resistance to various stresses, and immunity. Since the roots of the Ashwagandha plant are also known to be beneficial in treating ulcers, leucoderma and scabies, they have also been applied topically to heal skin sores and reduce swelling (7). These findings suggest that one or more components of Ashwagandha have active physiological effects on the skin. Studies on topical treatment with Ashwagandha organic and aqueous extracts have confirmed their chemopreventive effects on skin cancer (8) and their melanin regulatory effects (9). In addition, Ashwagandha, in the form of a paste of boiled leaves and roots, is considered to have wound-healing abilities in Ayurveda (10).
It has been determined that the main organic solvent extract of Ashwagandha is the water-insoluble Withaferin-A, and that Withaferin-A exhibits anti-inflammatory, antiangiogenesis, antimetastasis and anticancer activities (11). In Ayurveda, however, most herbal remedies are applied as a hot-water extract. Whether the healing effects of Withaferin-A would be observed by applying a hot-water extract of Ashwagandha (ASH-WEX) to skin remains largely unexplored.
Recently, a report determined that ASH-WEX had physiological activities and effects that were different than those of Withaferin-A, and were unrelated to Withaferin-A (12). Bhat et al (13) also reported that Ashwagandha tea...