Melasma is a difficult disorder to treat. With the removal of hydroquinone from the cosmetic market and the prevalence of dyschromia, new skin lightening ingredients are being sought and many new discoveries are coming from Asia.
There are more than 500 species of the genus Artemisia (of the Astraceae or Compositae family) dispersed throughout the temperate areas of Asia, Europe, and North America.1 Various parts of the shrub Artemisia capillaris, found abundantly in China, Japan, and Korea, have been used in traditional medicine in Asia for hundreds of years. A. capillaris (Yin-Chen in Chinese) has been deployed in traditional Chinese medicine as a diuretic, to protect the liver, and to treat skin inflammation.2,3 Antioxidant, anti-inflammatory, antisteatotic, antitumor, and antiviral properties have been associated with this plant,3 and hydrating effects have been recently attributed to it. In Korean medicine, A. capillaris (InJin in Korean) has been used for its hepatoprotective, analgesic, and antipyretic activities.4,5 In this column, the focus will be on recent evidence that suggests possible applications in skin care.
Chemical constituents
In 2008, Kim et al. studied the anticarcinogenic activity of A. capillaris, among other medicinal herbs, using the 7,12-dimethylbenz[a]anthracene (DMBA)-induced mouse skin carcinogenesis model. The researchers found that A. capillaris exhibited the most effective anticarcinogenic activity compared to the other herbs tested, with such properties ascribed to its constituent camphor, 1-borneol, coumarin, and achillin. Notably, the chloroform fraction of A. capillaris significantly lowered the number of tumors/mouse and tumor incidence compared with the other tested herbs.6
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The wide range of biological functions associated with A. capillaris, including anti-inflammatory, antioxidant, antidiabetic, antisteatotic, and antitumor activities have, in various studies, been attributed to the bioactive constituents scoparone, scopoletin, capillarisin, capillin, and chlorogenic acids.3
Tyrosinase-related protein 1 (TYRP-1) and its role in skin pigmentation
Tyrosinase related protein 1 (TYRP-1) is structurally similar to tyrosinase, but its role is still being elucidated. Mutations in TYR-1 results in oculocutaneous albinism. TYRP-1 is involved in eumelanin synthesis, but not in pheomelanin synthesis. Mutations in TYRP-1 affect the quality of melanin synthesized rather than the quantity.4 TYRP-1 is being looked at as a target for treatment of hyperpigmentation disorders such as melasma.
Effects on melanin synthesis
A. capillaris reduces the expression of TYRP-1, making it attractive for use in skin lightening products. Although there are not a lot of data, this is a developing area of interest and the following will discuss what is known so far.
Dr. Leslie S. Baumann
Kim et al. investigated the antimelanogenic activity of 10 essential oils, including A. capillaris, utilizing the B16F10 cell line model. A. capillaris was among four extracts found to hinder melanogenesis, and the only one that improved cell proliferation, displayed anti-H2O2 activity, and reduced tyrosinase-related protein (TRP)-1 expression. The researchers determined that A. capillaris extract suppressed melanin production through the downregulation of the TRP 1 translational level. They concluded that while investigations using in vivo models are necessary to buttress and validate these results, A. capillaris extract appears to be suitable as a natural therapeutic antimelanogenic agent as well as a skin-whitening ingredient in cosmeceutical products.7
Tabassum et al. screened A. capillaris for antipigmentary functions using murine cultured cells (B16-F10 malignant melanocytes). They found that the A. capillaris constituent 4,5-O-dicaffeoylquinic acid significantly and dose-dependently diminished melanin production and tyrosinase activity in the melanocytes. The expression of tyrosinase-related protein-1 was also decreased. Further, the researchers observed antipigmentary activity in a zebrafish model, with no toxicity demonstrated by either A. capillaris or its component 4,5-O-dicaffeoylquinic acid. They concluded that this compound could be included as an active ingredient in products intended to address pigmentation disorders.8