Melanin biosynthesis inhibitory effects of calycosin-7-O-β-d-glucoside isolated from astragalus (Astragalus membranaceus)

To discover an active skin depigmentation agent, we isolated a melanin biosynthesis inhibitor from the methanol extract of astragalus (Astragalus membranaceus) using a bioactivity-guided fractionation and identified it as calycosin-7-O-β-d-glucoside via spectroscopic analysis. The active compound exhibited tyrosinase inhibitory activity with an IC₅₀ value of 68 μM. In addition, calycosin-7-O-β-d-glucoside showed a melanin biosynthesis inhibition zone in a culture plate of Streptomyces bikiniensis. Furthermore, 75.78 μM of calycosin-7-O-β-d-glucoside dramatically decreased 50% of the melanin content on Melan-a cells without any apparent cytotoxicity. Theses results indicate that the calycosin-7-O-β-d-glucoside isolated from astragalus may be a good candidate for skin-whitening agent.     

Effects of aloesin on melanogenesis in pigmented skin equivalents

Reconstituted 3-dimensional human skin equivalents in vitro are gaining popularity for studies of skin metabolism and depigmenting agents because they exhibit morphological and growth characteristics similar to human skin. The effects of aloesin on melanogenesis, however, have never been examined with the pigmented skin equivalent. The purpose of the study was to construct the skin equivalent and observe the effects of aloesin on melanogenesis in the model. We constructed an in vitro pigmented skin equivalent and examined the general structure and condition of the pigmented skin equivalent with H&E staining and Fontana Masson staining. Then, we examined the effects of aloesin on tyrosinase activity and formation of melanin in the model. Such a pigmented skin model demonstrated morphology similar to that seen in normal skin and can be used to assess the regulation of pigmentation by melanogenic compounds. The results suggested that aloesin had direct inhibitory effects on melanogenesis and showed dose-dependent reductions in tyrosinase activity (P < 0.05) and melanin content (P < 0.05). In conclusion, our study indicated that skin equivalents provided a convenient and cost-effective alternative to animal testing for evaluating the regulation of pigmentation. Aloesin showed promise as a pigmentation-altering agent for cosmetic or therapeutic applications.     

Inhibitory effects of chestnut inner skin extracts on melanogenesis

Antioxidant capacities (ABTS radical scavenging assay and ferric reducing/antioxidant power assay), mushroom tyrosinase inhibitory effect, and α-melanocyte stimulating hormone (α-MSH) induced melanogenesis inhibitory effect of 60% methanol extracts and ethylacetate fractions from chestnut inner skin in B16F10 cells were investigated to inspect whitening effect. Above research showed that 60% methanol extracts and ethylacetate fractions from chestnut inner skin resulted in a dose-dependent manner on in vitro antioxidant effects. Especially, the ethylacetate fractions inhibited enzyme activity of mushroom tyrosinases with an IC₅₀ value of 160 μg/mL. Ethylacetate fractions from chestnut inner skin also decreased cellular melanin synthesis in B16F10 melanoma cells. Expression of tyrosinase showed that ethylacetate fractions from chestnut inner skin significantly decreased cellular melanogenesis. Consequently, these results suggest that chestnut inner skin extracts can be considered for a whitening agent of human skin.     

Kinetic analysis of melanogenesis by means of Agaricus bisporus tyrosinase

Melanins are a heterogeneous group of polymers formed by enzymatic reactions in vegetable tissues that contain phenolic or polyphenolic molecules. Recent studies have discovered some beneficial properties of melanins on health, making that not only its elimination should be reconsidered, but also its addition could be proposed to functional food of new creation. A further knowledge about the kinetic mechanism of melanogenesis is required prior to its possible industrial utilization. In this work, the kinetics of melanogenesis from 4-methylcatechol using mushroom tyrosinase and measuring the absorbance of the solution has been analyzed. The reaction pathway has been divided in two steps, and a mathematical expression has been developed to describe each one of them. The first one, an enzymatic reaction from the o-diphenol to colorless intermediate products. The second one, a polymerization of these intermediates leading to melanin chains. These expressions allow describing melanin formation as a function of reaction time, including some important parameters such as the extinction coefficient. In addition, the effect of pH and substrate concentration has been assayed in melanogenesis from two kinds of tyrosinase substrates: monophenolic (l-tyrosine) and o-diphenolic (4-methylcatechol).     

Dual inhibitions of lemon balm (<Emphasis Type="Italic">Melissa officinalis</Emphasis>) ethanolic extract on melanogenesis in B16-F1 murine melanocytes: Inhibition of tyrosinase activity and its gene expression

The effects of wild type and UV-irradiated lemon balm (Melissa officinalis) ethanolic extracts (MOE and UMOE) on melanogenesis in vitro were examined. UMOE showed potent antioxidant activity and significantly inhibited the mushroom and melanocyte tyrosinase activity, and lowered cellular melanin content by 49% at 200 μg/mL in B16-F1 melanocytes. The key gene and protein expression of tyrosinase, tyrosinase-related protein (TRP)-1, and TRP-2 were reduced (−73% for TRP-1 protein at 200 μg/mL UMOE, p<0.05). MOE showed similar results to a slightly lesser degree. We found that myo-inositol, a major compound in lemon balm extracts, significantly reduced cellular melanin synthesis and its effect was greater than arbutin at 1 mM. These suggest that both MOE and UMOE have anti-melanogenic role by both direct inhibition of tyrosinase and down-regulation of gene expressions in melanogenesis. UV-irradiation slightly improved the anti-melanogenic activities. UMOE may be useful as natural anti-melanogenic biomaterials for functional foods and cosmetics.     

The melanogenesis and mechanisms of skin-lightening agents--existing and new approaches

Skin-lightening products are commercially available for cosmetic purposes to obtain lighter skin complexion. Clinically, they are also used for treatment of hyperpigmentary disorders such as melasma, café au lait spot and solar lentigo. All of these target naturally melanin production, and many of the commonly used agents are known as competitive inhibitors of tyrosinase, one of the key enzymes in melanogenesis. In this review, we present an overview of commonly used skin-whitening ingredients that are commercialized, but we also hypothesize on other mechanisms that could be important targets to control skin pigmentation such as for example regulation of the adrenergic and glutaminergic signalling and also control of tetrahydrobiopterins in the human skin.     

Effects of protein hydrolysate from chicken feather meal on tyrosinase activity and melanin formation in B16F10 murine melanoma cells

Tyrosinase is a copper-containing enzyme that controls mammalian melanogenesis. Tyrosinase inhibitors are important for their potential application in cosmetic products. Chicken feather meal is a rich source of amino acids, which have been linked with tyrosinase inhibition activity. This study investigated the tyrosinase inhibitory properties of protein hydrolysates prepared from chicken feather meal. Protein hydrolysates prepared by pepsin-pancreatin with MW <3 kDa exhibited strong tyrosinase inhibition activity for both monophenolase (IC₅₀ 5.780 ± 0.188 µg/mL) and diphenolase activities (IC₅₀ 0.040 ± 0.024 µg/mL) in a cell-free mushroom tyrosinase system. These samples were uncompetitive inhibitors with Ki values of 18.149 and 27.189 µg/mL in monophenolase and diphenolase activities, respectively. A cell culture model showed that this hydrolysate had the strongest inhibition on the viability of B16F10 cells (IC₅₀ 1.124 ± 0.288 µg/mL) and 0.210 µg/mL of the sample exhibited inhibition of tyrosinase activity by 50.493% and melanin synthesis by 14.680% compared to the control.     

Comparative evaluation of rosmarinic acid,methyl rosmarinate and pedalitin isolated from Rabdosia serra (MAXIM.) HARA as inhibitors of tyrosinase and α-glucosidase

Rabdosia serra has been used in traditional Chinese medicine for centuries. In order to illustrate the pharmaceutical activity of R. serra as hypoglycaemic and skin-whitening agents, rosmarinic acid (confirmed as the major compound in R. serra), methyl rosmarinate and pedalitin isolated from R. serra were evaluated for their inhibitory effects and mechanisms on tyrosinase and α-glucosidase. The inhibitory effects on both tyrosinase and α-glucosidase were in decreasing order, pedalitin > methyl rosmarinate > rosmarinic acid. The IC₅₀ values for the tyrosinase and α-glucosidase activity inhibited by pedalitin were 0.28 and 0.29 mM, respectively. Both rosmarinic acid and methyl rosmarinate were considered as noncompetitive inhibitors of tyrosinase, while pedalitin was suggested to be a mixed-type inhibitor of tyrosinase. In the assay of α-glucosidase inhibition, rosmarinic acid was found to be a competitive inhibitor, whereas both methyl rosmarinate and pedalitin were considered as mixed-type inhibitors.     

Antimelanogenic and antioxidative effects of residual powders from Shochu distillation remnants

Shochu distillation remnants (SDR) are by-products in the manufacturing process of the Japanese liquor Shochu and include various useful organic compounds derived from the fermentation of grains. In this study, we investigated the inhibitory effects of barley-, black rice-, rice-, and sweet potato-powder from Shochu distillation remnants (PSDR) on the melanogenesis of B16 cells. Barley- and black rice-PSDR showed significant decrease in the intracellular melanin content and tyrosinase activity without cytotoxicity in the concentration range of 500–1000 μg/mL. Significantly, the antioxidative capacity of PSDR correlated well with the antimelanogenesis on the basis of a radical-scavenging assay. Furthermore, some antioxidant polyphenols in PSDR were identified by HPLC and the amount of the polyphenols was in good agreement with the antimelanogenic effects of PSDR. These results indicated that the polyphenols are the active components of PSDR for the antimelanogenesis of B16 cells. This study suggests that barley- and black rice-PSDR could be novel antimelanogenic materials for skin whitening.     

Isolation,Purification, and Structural Features of a Polysaccharide from Phellinus linteus and Its Hypoglycemic Effect in Alloxan‐Induced Diabetic Mice

Phellinus linteus is a medicinal mushroom that has been used in Oriental countries for centuries for its antitumor, antioxidant, immunomodulatory, and biological activity on hyperglycemia. A water‐soluble crude polysaccharide was extracted using hot water from P. linteus mycelia grown under submerged culture. An orthogonal experiment was used to optimize the extraction conditions of P. linteus mycelia polysaccharides (PLP). The crude polysaccharide was purified using DEAE Sephadex A‐50 and Sephadex G‐200 chromatography. Fourier transform infrared (FT‐IR) spectroscopy and nuclear magnetic resonance (¹H NMR) spectroscopy were used to investigate the structure of the purified P. linteus polysaccharide (PLP‐I), revealing that it was mainly a branched‐type glycan with both α‐ and β‐linkages and a pyranoid sugar ring conformation. PLP orally administered at 100 mg/kg body weight/d could significantly reduce the blood glucose level by 35.60% in alloxan‐induced diabetic mice. The results of an oral glucose tolerance test (OGTT) revealed that PLP had an effect on glucose disposal after 28 d of treatment. The result revealed that PLP from a submerged culture of P. linteus mycelia possessed potent hypoglycemic properties. The polysaccharide may be useful as a functional food additive and a hypoglycemic agent.     

Flaniostatin, a new isoflavonoid glycoside isolated from the leaves of Cudrania tricuspidata as a tyrosinase inhibitor

In the course of screening program for skin whitening compounds, flaniostatin (FST) was isolated from the leaves of Cudrania tricuspidata as a novel inhibitor of tyrosinase. The structure of FST was determined by ESI-MS and NMR spectroscopic analyses as a new isoflavone glycoside. The FST was exhibited a tyrosinase inhibitory effect in a dose-dependent manner. This effect was higher than that of arbutin at the same concentrations. These results indicated that FST isolated from C. tricuspidata may be a positive tool for skin-whitening agent research.     

Antioxidant activity and melanogenesis inhibitory effect of the acetonic extract of Osmanthus fragrans: A potential natural and functional food flavor additive

Osmanthus fragrans, a common flavor additive for tea and other beverages, has potential applications in biomedical science. In this study, we investigated O. fragrans acetonic extract (OFE) for its total phenolic and flavonoid contents, radical-scavenging activity, and potential anti-tyrosinase ability. OFE possessed considerable amounts of phenolics (264.7 mg gallic acid equivalent/g of extract) and flavonoids (190.7 mg catechin equivalent/g of extract). The antioxidation activities, measured in terms of EC₅₀ values using DPPH and ABTS⁺ assays, were 304.9 mg ascorbic acid equivalent/g of extract and 516.3 mg trolox equivalent/g of extract, respectively. LC-MS results discovered the presence of luteolin in the extract, and a kinetic study revealed an uncompetitive inhibitory effect of OFE upon the oxidation of tyrosine (IC₅₀ = 2.314 mg/mL) and l-DOPA (IC₅₀ = 44.20 mg/mL). In addition, we tested OFE in vitro (B16F10 cells) for its anti-tyrosinase activity and anti-melanin formation and found that OFE was able to reduce the tyrosinase activity and melanin formation of B16F10 cells in a dose-dependent manner. Our findings support that O. fragrans is a potential natural, functional antioxidant food favor additive. Additionally, because OFE inhibits melanin formation, it appears to have potential use as an anti-browning food additive, in skin-whitening cosmetics, or as a new drug for treating melanoma.     

Anti-proliferative properties of ethyl acetate extract of Phellinus linteus grown on ginseng (Panax ginseng) on HT-29 human colon carcinoma cells through inducing apoptosis

Phellinus linteus (PL) and ginseng (Panax ginseng, PG) have been widely used as traditional herbal medicines in East Asia. In this study, we evaluated whether the extract of P. linteus grown on ginseng (PGP) exhibited an more enhanced anti-proliferative activity on HT-29 human colon carcinoma cells than PL or PG extract. PGP EtOAc extract inhibited HT-29 cancer cell viability stronger than PG or PL EtOAc extract. FACS analysis revealed that PGP EtOAc extract increased sub-G1 (apoptotic) HT-29 cell population. The nuclear structures of HT-29 cells were disrupted, resulting in apoptotic fragments (45 kDa) of lamin B after treating PGP EtOAc extract. PGP EtOAc extract induced activation of caspase-8 and -9 in HT-29 cells. These results suggest that the PGP EtOAc extract has a direct anti-cancer effect through apoptosis and cell cycle blockade in HT-29 human colon carcinoma cells.