The increased amount of melanin leads to skin disorders such as age spots, freckles, melasma and malignant melanoma. Tyrosinase is known to be the key enzyme in melanin production. Plants and their extracts are inexpensive and rich resources of active compounds that can be utilized to inhibit tyrosinase as well as can be used for the treatment of dermatological disorders associated with melanin hyperpigmentation. Using in vitro tyrosinase inhibitory activity assay, extracts from 13 plant species from Brazilian Cerrado were evaluated. The results showed that Pouteria torta and Eugenia dysenterica extracts presented potent in vitro tyrosinase inhibition compared to positive control kojic acid. Ethanol extract of Eugenia dysenterica leaves showed significant (p<0.05) tyrosinase inhibitory activity exhibiting the IC50 value of 11.88 µg/mL, compared to kojic acid (IC50 value of 13.14 µg/mL). Pouteria torta aqueous extract leaves also showed significant inhibitory activity with IC50 value of 30.01 µg/mL. These results indicate that Pouteria torta and Eugenia dysenterica extracts and their isolated constituents are promising agents for skin-whitening or antimelanogenesis formulations.

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Plants from Brazilian Cerrado with Potent Tyrosinase Inhibitory Activity

The aim of this work was to investigate the anticancer cytotoxic effects of natural compound subamolide E on the human skin cancer melanoma A375.S2 cells. Subamolide E was isolated from Cinnamomum subavenium and demonstrated cytotoxicities in the cell-growth assay at concentration ranges from 0 to 100 μM at 24 h. Propidium iodide staining and flow cytometry analyses were used to evaluate cell-cycle distribution and found that subamolide E caused DNA damage in the sub-G1 phase with a dose-dependent manner after 24 h of treatment. According to the western blot result, subamolide-E-treated cells with the increase of caspase-dependent apoptotic proteins induced related pathway mechanisms. Subamolide E also showed antimigratory activities of A375.S2 cells on the wound-healing assay. Finally, subamolide E demonstrated minor cytotoxicities to normal human skin cells (keratinocytes, melanocytes, and fibroblasts); therefore, it is a potential chemotherapeutic agent against skin melanoma.

Subamolide E from Cinnamomum subavenium induces sub-G1 cell-cycle arrest and caspase-dependent apoptosis and reduces the migration ability of human melanoma cells.

In this work, one of Zingiber officinale components, 10-shogaol, was tested with 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging, metal chelating ability, and reducing power to show antioxidant activity. 10-Shogaol promoted human normal epidermal keratinocytes and dermal fibroblasts cell growths. 10-Shogaol enhanced growth factor production in transforming growth factor-β (TGF-β), platelet derived growth factor-αβ (PDGF-αβ) and vascular endothelial growth factors (VEGF) of both cells. In the in vitro wound healing assay for 12 or 24 h, with 10-shogaol, the fibroblasts and keratinocytes migrated more rapidly than the vehicle control group. Thus, this study substantiates the target compound, 10-shogaol, as an antioxidant for human skin cell growth and a migration enhancer with potential to be a novel wound repair agent.

10-Shogaol, an Antioxidant from Zingiber officinale for Skin Cell Proliferation and Migration Enhancer

Polygonum cuspidatum extracts as bioactive antioxidaion, anti-tyrosinase, immune stimulation and anticancer agents.

Equisetum ramosissimum, a genus of Equisetaceae, is a medicinal plant that can be separated into ethyl acetate (EA), dichloromethane (DM), n-hexane (Hex), methanol (MeOH), and water extracts. EA extract was known to have potent antioxidative properties, reducing power, DPPH scavenging activity, and metal ion chelating activity. This study compared these five extracts in terms of their inhibiting effects on three human malignant melanomas: A375, A375.S2, and A2058. MTT assay presented the notion that both EA and DM extracts inhibited melanoma growth but did not affect the viabilities of normal dermal keratinocytes (HaCaT) or fibroblasts. Western blot analyses showed that both EA and DM extracts induced overexpression of caspase proteins in all three melanomas. To determine their roles in melanogenesis, this study analyzed their in vitro suppressive effects on mushroom tyrosinase. All extracts except for water revealed moderate suppressive effects. None of the extracts affected B16-F10 cells proliferation. EA extract inhibited cellular melanin production whereas DM extract unexpectedly enhanced cellular pigmentation in B16-F10 cells. Data for modulations of microphthalmia-associated transcription factor, tyrosinase, tyrosinase-related protein 1, and tyrosinase-related protein 2 showed that EA extract inhibited protein expression mentioned above whereas DM extract had the opposite effect. Overall, the experiments indicated that the biofunctional activities of EA extract contained in food and cosmetics protect against oxidation, melanoma, and melanin production.

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Biofunctional Activities of Equisetum ramosissimum Extract: Protective Effects against Oxidation, Melanoma, and Melanogenesis.

A new amide, dihydro-feruloyl-5-methoxytyramine ( 1 ), along with 13 known compounds, including (+)-syringaresinol ( 2 ), (+)- epi -syringaresinol ( 3 ), 4-acetonyl-3,5-dimethoxy- p -quinol ( 4 ), cis - p -coumaric acid ( 5 ), trans - p -coumaric acid ( 6 ), p -hydroxybenzoic acid ( 7 ), syringic acid ( 8 ), vanillic acid ( 9 ), veratric acid ( 10 ), N - cis -feruloyltyramine ( 11 ), N - trans -feruloyltyramine ( 12 ) and N - cis -caffeoyltyramine ( 13 ), were isolated from the stems of Synsepalum dulcificum Daniell (Sapotaceae). The structures of these compounds were established on the basis of spectroscopic analysis. One of the purposes of this study was to survey the antioxidant properties of 13 pure constituents. The radical scavenging and antioxidant activities were investigated by: scavenging of 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radicals; metal chelating power was completed by ferrous ions; and reducing power was demonstrated by iron ions reduction reaction. In addition, all compounds were evaluated for their cell proliferation inhibition activities on human skin melanoma cells and tyrosinase inhibitions. The anti-tyrosinase effects were to calculate the hydroxylation of l -tyrosine to l -dopa according to in vitro mushroom tyrosinase assay. In sum, the inhibition effects of compounds ( 2 – 3 ) on human melanoma cells were significant. Besides, DPPH, ABTS radical scavenging, metal chelating and reducing power were found to be moderate compared with the positive controls.

Bioconstituents from stems of Synsepalum dulcificum Daniell (Sapotaceae) inhibit human melanoma proliferation, reduce mushroom tyrosinase activity and have antioxidant properties

Woei-Ling Yang

Papers

Bioconstituents from stems of Synsepalum dulcificum Daniell (Sapotaceae) inhibit human melanoma proliferation, reduce mushroom tyrosinase activity and have antioxidant properties

A novel homosesquiterpenoid from the stems of Cinnamomum burmanii