Inhibitory effect of an ellagic acid-rich pomegranate extract on tyrosinase activity and ultraviolet-induced pigmentation

The use of botanical extracts as topical skin-lightening agents for the improvement of skin pigmentation disorders

Both physicians and dermatology patients are searching for long-term topical skin care solutions (both cosmetic and cosmeceutical) to address problems presented by skin hyperpigmentation. Specifically, some women often express a desire to "lighten" skin tone by achieving improved visible tone, reduction in yellowness (or sallow tone), and reduction in the appearance of hyperpigmented spots ("age" or "sun" spots). Traditional depigmenting agents, such as hydroquinone, corticosteroids, and kojic acid, although highly effective, can raise several safety concerns (for example, ochronosis, atrophy, carcinogenesis, and other local or systemic side effects) with long-term exposure. An understanding of the benefits of natural and botanical extracts provides opportunities to develop new products to address pigmentation problems. Active compounds isolated from plants, such as arbutin, aloesin, gentisic acid, flavonoids, hesperidin, licorice, niacinamide, yeast derivatives, and polyphenols, inhibit melanogenesis without melanocytotoxicity by different mechanisms. This review presents an overview of trends in the application of plant extracts as topical treatments for hyperpigmentation disorders. It highlights some of the most relevant natural extracts, providing in vitro screening results and relevant available clinical study trial findings supporting their efficacy.

Effects on tyrosinase activity by the extracts of Ganoderma lucidum and related mushrooms

The inhibitory effects on tyrosinase activity by extracts of several mushrooms belonging to Basidiomycetes were evaluated. Among the tested mushrooms (Ganoderma lucidum, Antrodia camphorata, Agaricus brasiliensis, and Cordyceps militaris), G. lucidum exhibited significant inhibition of tyrosinase activity (IC(50) value 0.32 mg/ml), compared to those prepared from other Basidiomycetes. Tyrosinase inhibitors are effective components of skin-lightening compounds and other cosmetics; currently many of the facial mask cosmetics in the market contain Ganoderma extracts in their ingredients. The finding that mushroom extracts contain tyrosinase activity inhibition will contribute to better understanding of how their 'healing' properties in various Chinese traditional herbal on skin care products.

Byelyankacin: a novel melanogenesis inhibitor produced by Enterobacter sp. B20

A novel melanogenesis inhibitor, byelyankacin (1), was isolated from the fermentation broth of a bacterial strain. The producing organism, designated B20, was identified as a member of the genus Enterobacter based on taxonomic characteristics. 1 was obtained as a white powder from the culture medium by solvent extraction and serial chromatographic purification. The structure of 1 was determined as (E)-4-(2-isocyanovinyl)phenyl alpha-L-rhamnopyranoside on the basis of spectroscopic data. 1 potently inhibited mushroom tyrosinase and melanogenesis of B16-2D2 melanoma cells with IC50 value of 2.1 nM and 30 nM, respectively.

Hypopigmenting agents: an updated review on biological, chemical and clinical aspects

An overview of agents causing hypopigmentation in human skin is presented. The review is organized to put forward groups of biological and chemical agents. Their mechanisms of action cover (i) tyrosinase inhibition, maturation and enhancement of its degradation; (ii) Mitf inhibition; (iii) downregulation of MC1R activity; (iv) interference with melanosome maturation and transfer; (v) melanocyte loss, desquamation and chemical peeling. Tyrosinase inhibition is the most common approach to achieve skin hypopigmentation as this enzyme catalyses the rate-limiting step of pigmentation. Despite the large number of tyrosinase inhibitors in vitro, only a few are able to induce effects in clinical trials. The gap between in-vitro and in-vivo studies suggests that innovative strategies are needed for validating their efficacy and safety. Successful treatments need the combination of two or more agents acting on different mechanisms to achieve a synergistic effect. In addition to tyrosinase inhibition, other parameters related to cytotoxicity, solubility, cutaneous absorption, penetration and stability of the agents should be considered. The screening test system is also very important as keratinocytes play an active role in modulating melanogenesis within melanocytes. Mammalian skin or at least keratinocytes/melanocytes co-cultures should be preferred rather than pure melanocyte cultures or soluble tyrosinase.

Coenzyme Q_{10} effects on manganese superoxide dismutase and glutathione peroxidase in the hairless mouse skin induced by ultraviolet B irradiation

Coenzyme Q_{10} (CoQ_{10}) is a naturally occurring antioxidant and a prominent component of mitochondrial electron transport chain. In the present study, we investigated the effect of CoQ_{10} nanoparticle against photoaging using immunohistochemistry and Western blot analysis in the hairless mouse skin induced by ultraviolet B (UVB) irradiation (300 mJ/cm;{2}, 3 min/day for 21 days). In the UVB-irradiated distilled water (DW)-treated group, manganese superoxide dismutase (SOD2) and glutathione peroxidase (GPx) immunoreactivity and their protein levels in the skin were significantly lower than those in the control group. However, SOD2 and GPx immunoreactivity and their protein levels in the skin of the UVB-irradiated CoQ_{10}-treated group were higher than those in the UVB-irradiated DW-treated group. GPx activity in the skin in the UVB-irradiated DW-treated group significantly decreased compared to that in the control group; whereas GPx activity in the UVB-irradiated CoQ_{10}-treated group was similar to that in the control group. These results suggest that CoQ_{10} strongly inhibits oxidative stress in the skin induced by UVB via increasing SOD2 and GPx.

Effects of Oral Administration of Ellagic Acid-Rich Pomegranate Extract on Ultraviolet-Induced Pigmentation in the Human Skin

We performed a double-blind, placebo-controlled trial to clinically evaluate the protective and ameliorative effects of ellagic acid-rich pomegranate extract on pigmentation in the skin after ultraviolet ray (UV) irradiation, using female subjects in their 20s to 40s. Thirteen healthy volunteers per group were randomly assigned to three groups; namely, high dose (200 mg/d ellagic acid), low dose (100 mg/d ellagic acid) and control (0 mg/d ellagic acid: placebo). Each group received the respective test foods for 4 wk. Each subject received a 1.5 MED (minimum erythema dose) of UV irradiation on an inside region of the right upper arm, based on the MED value measured on the previous day. Luminance (L), melanin and erythema values were measured before the start of the test food intake, and after 1, 2, 3 and 4 wk following the start of the test food intake. Further, questionnaires were conducted regarding the condition of the skin before the start of the test food intake and at the termination of the test food intake. As a result, decreasing rates of L values from the baseline in the low- and high-dose groups were inhibited by 1.35% and 1.73% respectively, as compared to the control group. Further, a stratified analysis using subjects with a slight sunburn revealed an inhibited decrease of L values compared with the control group at 1, 2 (p<0.01, respectively) and 4 wk (p<0.05) after the start of the test food intake in the low-dose group, and at 2 and 3 wk (p<0.05) in the high-dose group. Furthermore, the results of questionnaires showed ameliorating tendencies due to the test food, in some items such as "brightness of the face" and "stains and freckles." Based on the above-mentioned results, it is suggested that ellagic acid-rich pomegranate extract, ingested orally, has an inhibitory effect on a slight pigmentation in the human skin caused by UV irradiation.