Melanogenesis Inhibitory Activity, Chemical Components and Molecular Docking Studies of Prunus cerasoides Buch.-Ham. D. Don. Flowers.

Safe depigmenting agents are currently increasing in the cosmetic or pharmaceutical industry because various compounds have been found to have undesirable side effects. Therefore, the present study aimed to investigate the melanogenesis inhibitory effects of Prunus cerasoides Buch. -Ham. D. Don. flower extracts and their molecular mechanism in B16F10 mouse melanoma cells. Moreover, we also examined phenolic and flavonoid contents, antioxidant activity, chemical constituents of potential extracts, and molecular docking. The highest phenolic and flavonoid contents with the greatest scavenging activity were found in the butanol extract of the P. cerasoides flower compared to other extracts. From all extracts, only crude, diethyl ether, and butanol extracts showed an inhibition of mushroom tyrosinase activity, cellular tyrosinase activity, and melanin content as well as the downregulation of the gene expression of the microphthalmia-associated transcription factor (MITF), tyrosinase, tyrosinase-related protein-1 (TRP-1), and tyrosinase-related protein-2 (TRP-2) in α-MSH-stimulated B16F10 cells. Based on the molecular docking study, n-hexadecanoic acid, heptadecanoic acid, octadecanoic acid, 9,12-octadecadienoic acid, 9,12,15-octadecanoic acid, and eicosanoic acid might show an inhibitory effect against tyrosinase and MITF. In conclusion, this finding demonstrates that both the diethyl ether and butanol extracts of the P. cerasoides flower can effectively reduce tyrosinase activity and melanin synthesis through the downregulation of the melanogenic gene expression in B16F10 cells and through the molecular docking study. Taken together, the diethyl ether and butanol extracts of the P. cerasoides flower could be an anti-melanogenic ingredient for hyperpigmentary or melasma treatment.

Identification of Sitogluside as a Potential Skin-Pigmentation-Reducing Agent through Network Pharmacology.

Many traditional Chinese medicines (TCMs) with skin-whitening properties have been recorded in the Ben-Cao-Gang-Mu and in folk prescriptions, and some literature confirms that their extracts do have the potential to inhibit pigmentation. However, no systematic studies have identified the specific regulatory mechanisms of the potential active ingredients. The aim of this study was to screen the ingredients in TCMs that inhibit skin pigmentation through a network pharmacology system and to explore underlying mechanisms. We identified 148 potential active ingredients from 14 TCMs, and based on the average "degree" of the topological parameters, the top five TCMs (Fructus Ligustri Lucidi, Hedysarum multijugum Maxim., Ampelopsis japonica, Pseudobulbus Cremastrae Seu Pleiones, and Paeoniae Radix Alba) that were most likely to cause skin-whitening through anti-inflammatory processes were selected. Sitogluside, the most common ingredient in the top five TCMs, inhibits melanogenesis in human melanoma cells (MNT1) and murine melanoma cells (B16F0) and decreases skin pigmentation in zebrafish. Furthermore, mechanistic research revealed that sitogluside is capable of downregulating tyrosinase (TYR) expression by inhibiting the ERK and p38 pathways and inhibiting TYR activity. These results demonstrate that network pharmacology is an effective tool for the discovery of natural compounds with skin-whitening properties and determination of their possible mechanisms. Sitogluside is a novel skin-whitening active ingredient with dual regulatory effects that inhibit TYR expression and activity.

Antioxidant and Anti-Melanogenic Activities of Heat-Treated Licorice (Wongam, Glycyrrhiza glabra × G. uralensis) Extract.

Melanin is a brown or black pigment that protects skin from ultraviolet radiation and reactive oxygen species (ROS). However, overproduction of melanin is associated with lentigines, melasma, freckles and skin cancer. Licorice has shown antioxidant, anti-tumor, anti-platelet, anti-inflammatory and immunomodulatory activities and is used as a natural treatment for skin whitening. We aimed to confirm the potential of Wongam, a new cultivar of licorice developed by the Rural Development Administration (RDA), as a whitening agent in cosmetics. In addition, we verified the effect of heat treatment on the bioactivity of licorice by comparing antioxidant and anti-melanogenic activities of licorice extract before and after heating (130 °C). The heat-treated licorice extract (WH-130) showed higher radical-scavenging activities in the ABTS+ (2,2'-azino-bis-(3-ethylbenzothiazolin-6-sulfonic acid) diammonium salt) and DPPH (2,2-diphenyl-1-picrylhydrazyl) assays. In addition, WH-130 inhibited melanogenesis more effectively due to downregulation of tyrosinase in B16F10 melanoma cells than non-heated licorice extract. Moreover, heat treatment increased total phenolic content. In particular, isoliquiritigenin, an antioxidant and anti-melanogenic compound of licorice, was produced by heat treatment. In conclusion, WH-130, with increased levels of bioactive phenolics such as isoliquiritigenin, has potential for development into a novel skin whitening material with applications in cosmetics.

Identification of Tyrosinase Inhibitors and Their Structure-Activity Relationships via Evolutionary Chemical Binding Similarity and Structure-Based Methods.

Tyrosinase is an enzyme that plays a crucial role in the melanogenesis of humans and the browning of food products. Thus, tyrosinase inhibitors that are useful to the cosmetic and food industries are required. In this study, we have used evolutionary chemical binding similarity (ECBS) to screen a virtual chemical database for human tyrosinase, which resulted in seven potential tyrosinase inhibitors confirmed through the tyrosinase inhibition assay. The tyrosinase inhibition percentage for three of the new actives was over 90% compared to 61.9% of kojic acid. From the structural analysis through pharmacophore modeling and molecular docking with the human tyrosinase model, the pi-pi interaction of tyrosinase inhibitors with conserved His367 and the polar interactions with Asn364, Glu345, and Glu203 were found to be essential for tyrosinase-ligand interactions. The pharmacophore features and the docking models showed high consistency, revealing the possible essential binding interactions of inhibitors to human tyrosinase. We have also presented the activity cliff analysis that successfully revealed the chemical features related to substantial activity changes found in the new tyrosinase inhibitors. The newly identified inhibitors and their structure-activity relationships presented here will help to identify or design new human tyrosinase inhibitors.

Evaluation of the effect of narrow band-ultraviolet B on the expression of tyrosinase, TYRP-1, and TYRP-2 mRNA in vitiligo skin and their correlations with clinical improvement: A retrospective study.

Narrowband-ultraviolet B (NB-UVB) is considered one of the main therapeutic tools in vitiligo, which is able to induce repigmentation and halt depigmentation. However, little remains known about the effect of NB-UVB on TYR gene family, the main pigmentary genes, in vitiligo patients. To assess the effect of NB-UVB on expression of some genes related to the pigmentary problem of vitiligo; tyrosinase (TYR), tyrosinase related protein 1 (TYRP1) and tyrosinase related protein 2 (TYRP2), mRNA levels of those genes were quantitatively evaluated by Real-Time quantitative Polymerase Chain Reaction (RT-qPCR) in skin biopsies obtained from 30 patients with nonsegmental vitiligo and five healthy controls. Vitiligo patients were classified into two groups; group 1, involving 12 untreated vitiligo patients and group 2, including 18 vitiligo patients treated by NB-UVB. The levels of TYR, TYRP-1, and TYRP-2 mRNAs in untreated group were significantly lower than in control subjects (P < .001). In NB-UVB treated group, the three genes were significantly higher than in group 1 (P < .001), however, they were still significantly lower than in the control subjects (P < .001). A significant positive correlation was detected between TYR and TYRP-2 genes in group 2 (P = .03). This study demonstrated that mRNA level of TYR, TYRP-1, and TYRP-2, which decreased in vitiligo, was significantly increased upon treatment with NB-UVB. Accordingly, the mechanism of depigmentation in vitiligo disease and repigmentation by NB-UVB treatment may be related to the changes in the expression of these genes.

Soluble Pearl Extract provides effective skin lightening by antagonizing endothelin.

BACKGROUND: Incidence of skin pigmentation disorders has been on the rise globally. This calls for safer and more effective topical skin lightening and freckle-removing products. In this study, we hypothesized that Soluble Pearl Extract (SPE) may possess endothelin antagonizing compounds with good skin whitening effects. OBJECTIVES: (a) To determine the effect and mechanisms of SPE on ET-1-treated B16 melanoma cells. (b) To explore the cytotoxic effects of SPE on B16 melanoma cells. METHODS: CCK-8 assay was performed to determine how SPE and ET-1 affect the proliferation rate of B16 melanoma cells, the NaOH lysis assay was conducted to quantify the content of melanin while the tyrosinase activity was determined by DOPA oxidation test. The mRNA and protein expression levels of TYR and TRP-1 were determined by qRT-PCR assay and Western blot assay, respectively. RESULTS: We found that SPE at 0.1 and 1 µg/mL concentrations has no effect on the proliferation of the cells and 10 nmol/L ET-1 promoted B16 melanoma cells proliferation. Notably, B16 melanoma cells treated with 10 nmol/L ET-1 exhibited significantly higher melanin synthesis, tyrosinase activity, TYR, and TRP-1 mRNA expression levels compared with untreated cells. Of note, the effects of 10 nmol/L ET-1 treatment were abolished with SPE in a dose-dependent manner. CONCLUSIONS: SPE inhibits endothelin thereby safely and effectively lightening lightens the skin by antagonizing endothelin. Moreover, SPE is safe and effective.

Capsaicin Inhibits the Expression of Melanogenic Proteins in Melanocyte via Activation of TRPV1 Channel: Identifying an Inhibitor of Skin Melanogenesis.

Chili pepper belongs to the genus Capsicum of Solanaceae family. Capsaicin is the primary capsaicinoid in placenta and flesh of chili pepper fruit, which has been shown to have various pharmacological functions, including gastric protection, anti-inflammation, and obesity treatment. Here, we revealed that capsaicin as well as chilli extract was able to inhibit synthesis of melanin in melanocytes. In cultured melanocytes, the melanin content was reduced to 54 ± 6.55% and 42 ± 7.41% with p < 0.001 under treatment of 50 µM capsaicin for 24 and 72 h, respectively. In parallel, the protein levels of tyrosinase and tyrosinase-related protein-1 were reduced to 62 ± 8.35% and 48 ± 8.92% with p < 0.001. Such an inhibitory effect of capsaicin was mediated by activation of transient receptor potential vanilloid 1-induced phosphorylation of extracellular signal-regulated kinase. This resulted in a degradation of microphthalmia-associated transcription factor, leading to reduction of melanogenic enzymes and melanin. These results revealed that capsaicin could be an effective inhibitor for skin melanogenesis. Hence, chili pepper, as our daily food, has potential in dermatological application, and capsaicin should be considered as a safe agent in treating hyperpigmentation problems.

Lectins from the Edible Mushroom Agaricus bisporus and Their Therapeutic Potentials.

The mushroom Agaricus bisporus secretes biologically active compounds and proteins with benefits for human health. Most reported proteins from A. bisporus are tyrosinases and lectins. Lectins are of therapeutic or pharmaceutical interest. To date, only limited information is available on A. bisporus lectins and lectin-like proteins. No therapeutic products derived from A. bisporus lectin (ABL) are available on the market despite its extensive exploration. Recently, A. bisporus mannose-binding protein (Abmb) was discovered. Its discovery enriches the information and increases the interest in proteins with therapeutic potential from this mushroom. Furthermore, the A. bisporus genome reveals the possible occurrence of other lectins in this mushroom that may also have therapeutic potential. Most of these putative lectins belong to the same lectin groups as ABL and Abmb. Their relationship is discussed. Particular attention is addressed to ABL and Abmb, which have been explored for their potential in medicinal or pharmaceutical applications. ABL and Abmb have anti-proliferative activities toward cancer cells and a stimulatory effect on the immune system. Possible scenarios for their use in therapy and modification are also presented.

Melochia corchorifolia extract inhibits melanogenesis in B16F10 mouse melanoma cells via activation of the ERK signaling.

BACKGROUND: Numerous researches have focused on discovering available inhibitors of melanogenesis from natural medicinal plants with stable efficacy and safety to resolve cutaneous hyperpigmentary problems. Melochia corchorifolia Linn. (MC) has been used as folk medicine to treat various diseases. However, the effect of MC on melanogenesis remains unknown. AIM: In this study, we investigated the effect of MC extract on melanogenesis and its underlying mechanisms in B16F10 mouse melanoma cells. METHODS: B16F10 cells were treated with MC extract, and then, cell viability, melanin content, and tyrosinase activity were analyzed. The mRNA and protein expression of tyrosinase and microphthalmia-associated transcription factor (MITF) were evaluated using real-time quantitative polymerase chain reaction (RT-qPCR) and Western blotting, respectively. Phosphorylated or total protein levels in MC extract-induced signaling pathways were analyzed by Western blotting. RESULTS: Treatment of B16F10 cells with MC extract inhibited melanin synthesis and intracellular tyrosinase activity in a dose-dependent manner with no cytotoxicity. Protein and mRNA expressions of tyrosinase and MITF were also significantly decreased by MC extract treatment. In addition, phosphorylated level of extracellular signal-regulated kinase (ERK) was obviously increased by MC extract, but AKT pathway was not activated. Inhibited ERK phosphorylation by pretreatment with a selective ERK inhibitor PD98059 significantly reversed the decreased melanin content induced by treatment with MC extract in B16F10 cells. CONCLUSION: MC extract inhibits melanogenesis in B16F10 mouse melanoma cells through suppression of MITF-tyrosinase signaling pathway by ERK activation.

Reversing UVB-induced photoaging with Hibiscus sabdariffa calyx aqueous extract.

BACKGROUND: Hibiscus sabdariffa is commonly used in daily life and its extract is applied widely in food and cosmetics. However, it has not been evaluated for its anti-aging effects. RESULTS: Hibiscus sabdariffa calyx aqueous extract (HSCAE) has shown potential collagenase activity suppression effects, together with tyrosinase activity inhibition, and anti-oxidation as a free radical scavenger. The current investigation demonstrated that HSCAE was not cytotoxic in skin fibroblasts, and it significantly decreased ultraviolet B (UVB)-induced reactive oxygen species (ROS) on a flow cytometry assay. Moreover, HSCAE reduced matrix metalloproteinase (MMP) expression, increased tissue inhibition of metalloproteinase (TIMP)-1 level, and enhanced collagen content by inhibiting collagenase activity. It also blocked mRNA and protein expressions of melanin production pathway key factors, including the microphthalmia-associated transcription factor (MITF), tyrosinase, tyrosinase-related protein-1 (TRP-1), and dopachrome tautomerase-2 (TRP-2). CONCLUSION: These results demonstrated, for the first time, the potential of HSCAE as a natural antioxidant with the ability to maintain collagen production and to decrease melanin syntheses under UVB radiation, for anti-aging effects. © 2019 Society of Chemical Industry.

Flower extracts from Paeonia decomposita and Paeonia ostii inhibit melanin synthesis via cAMP-CREB-associated melanogenesis signaling pathways in murine B16 melanoma cells.

This investigation seeks to identify the effects of the EtOAc fractions of different flower parts of Paeonia decomposita (Pd) and Paeonia ostii (Po) on melanogenesis and their mechanisms of action in B16 melanoma cells. Cell viability assay showed that Pd-1, Po-1 (the petals of Pd or Po), Pd-3 and Po-3 (the stamens of Pd or Po) at 25 µg/ml produced lower toxic activities in B16 cells. Pd-1 and Po-1 extracts considerably reduced the melanin content and inhibited tyrosinase and DOPA oxidase activity. Moreover, Pd-1 and Po-1 down-regulated the expressions of MC1R, MITF, TRP-1, TRP-2, and tyrosinase. These extracts also reduce cAMP levels and inhibited the phosphorylation of CREB, which might be due to the presence of high concentrations of phenolic compounds and flavonoids. Our results suggested that Pd-1 and Po-1 are able to modulate the cAMP-CREB signaling pathway and down-regulate the melanogenesis-related proteins resulting in the observed anti-melanogenic effects. PRACTICAL APPLICATIONS: In China, the flower of Paeonia is often consumed as a dietary supplement and as an additive in skin whitening products. In November 2013, the National Health and Family Planning Commission of the People's Republic of China has approved the flower of Paeonia ostii as a novel food resource. The current study firstly demonstrated that the effects of EtOAc fractions of the petals of Paeonia decomposita (Pd) and Paeonia ostii (Po) considerably reduced the melanin content in B16 cells, which is due to the modulation of the cAMP-CREB signaling pathway followed by the down-regulation of melanogenesis-related proteins. Pd and Po extracts, as natural tyrosinase inhibitors, may serve as good candidates in food additives, cosmetic materials, or even in treating hyperpigmentation diseases.

Effect of Sucrier Banana Peel Extracts on Inhibition of Melanogenesis through the ERK Signaling Pathway.

Hyperpigmentation is a type of pigmentary disorder induced by overexpression of melanin content activated severe esthetic problems as melasma, freckle, ephelides, lentigo and other forms on human skin. Several whitening agents have restricted use because of their side effects or stability such as kojic acid, ascorbic acid and hydroquinone can act as cytotoxic substance which associated to dermatitis and skin cancer. To find for the safe substance, this study aimed to find for the ability of several components in Sucrier banana peel (SBP) extracts to inhibit melanogenesis process through p38 signaling pathway in B16F10 mouse melanoma cells. Tyrosinase activity and the cellular melanin content were dose dependent manner decreasing after SBP treatment. Furthermore, SBP decreased the expression of melanogenesis relate protein as microphthalmia-associated transcription factor (MITF) and tyrosinase protein after 24 hours incubation with α-melanocyte stimulating hormones (MSH) stimulating. The findings demonstrated that SBP contained an effective agent for hyperpigmentation inhibitor through p38 signaling pathways without any effect to ERK pathway, and subsequent down-regulate MITF expression and tyrosinase enzyme family production.

Effects of six compounds with different chemical structures on melanogenesis.

Several chemical compounds can restore pigmentation in vitiligo through mechanisms that vary according to disease etiology. In the present study, we investigated the melanogenic activity of six structurally distinct compounds, namely, scopoletin, kaempferol, chrysin, vitamin D3, piperine, and 6-benzylaminopurine. We determined their effectiveness, toxicity, and mechanism of action for stimulating pigmentation in B16F10 melanoma cells and in a zebrafish model. The melanogenic activity of 6-benzylaminopurine, the compound identified as the most potent, was further verified by measuring green fluorescent protein concentration in tyrp1 a: eGFP (tyrosinase-related protein 1) zebrafish and mitfa: eGFP (microphthalmia associated transcription factor) zebrafish and antioxidative activity. All the tested compounds were found to enhance melanogenesis responses both in vivo and in vitro at their respective optimal concentration by increasing melanin content and expression of TYR and MITF. 6-Benzyamino-purine showed the strongest re-pigmentation action at a concentration of 20 µmol·L-1in vivo and 100 µmol·L-1in vitro, and up-regulated the strong fluorescence expression of green fluorescent protein in tyrp1a: eGFP and mitfa: eGFP zebrafish in vitro. However, its relative anti-oxidative activity was found to be very low. Overall, our results indicated that 6-benzylaminopurine stimulated pigmentation through a direct mechanism, by increasing melanin content via positive regulation of tyrosinase activity in vitro, as well as up-regulating the expression of the green fluorescent protein in transgenic zebrafish in vivo.

Downregulation of α-Melanocyte-Stimulating Hormone-Induced Activation of the Pax3-MITF-Tyrosinase Axis by Sorghum Ethanolic Extract in B16F10 Melanoma Cells.

Ultraviolet irradiation-induced hyperpigmentation of the skin is associated with excessive melanin production in melanocytes. Tyrosinase (TYR) is a key enzyme catalyzing the rate-limiting step in melanogenesis. TYR expression is controlled by microphthalmia-associated transcription factor (MITF) expression. Sorghum is a cereal crop widely used in a variety of foods worldwide. Sorghum contains many bioactive compounds and is beneficial to human health. However, the effects of sorghum in anti-melanogenesis have not been well characterized. In this study, the biological activity of sorghum ethanolic extract (SEE) on α-melanocyte-stimulating hormone (α-MSH)-induced TYR expression was evaluated in B16F10 melanoma cells. SEE attenuated α-MSH-induced TYR gene promoter activity through the downregulation of the transcription factor MITF. We found that paired box gene 3 (Pax3) contributes to the maximal induction of MITF gene promoter activity. Further analysis demonstrated that SEE inhibited α-MSH-induced Pax3 expression. The collective results indicate that SEE attenuates α-MSH-induced TYR expression through the suppression of Pax3-mediated MITF gene promoter activity. Targeting the Pax3-MITF axis pathway could be considered a potential strategy to increase the efficacy of anti-melanogenesis.

Poria cocos Wolf extracts represses pigmentation in vitro and in vivo.

In skin, melanocytes determine skin color using melanogenesis, which induces protective mechanism to oxidative stress and UV damage. However, when melanin is excessive produced by the various stimulus, the accumulated melanin induces hyperpigmentation disease such as melasma, freckles, Melanism ware induced. Therefore, it is implicated to finding potential agents for whitening to be used in cosmetic products. In our present study, we show that Poria cocos Wolf extracts decreased melanin synthesis in B16F10. And then this inhibition of melanogenesis was provoked by regulation of tyrosinase activity and tyrosinase and MITF expression. Moreover, Poria cocos Wolf extracts contained cream improved skin tone using increase of bright value. Overall, these results provide evidence to potential agent for whitening to be used in cosmetic products.

Brown Mycelial Mat as an Essential Morphological Structure of the Shiitake Medicinal Mushroom Lentinus edodes (Agaricomycetes).

We show here, to our knowledge for the first time, that the brown mycelial mat of the xylotrophic shiitake medicinal mushroom, Lentinus edodes, not only performs a protective function owing to significant changes in the ultrastructure (thickening of the cell wall, increased density, and pigmentation of the fungal hyphae) but also is a metabolically active stage in the development of the mushroom. The cells of this morphological structure exhibit repeated activation of expression of the genes lcc4, tir, exp1, chi, and exg1, coding for laccase, tyrosinase, a specific transcription factor, chitinase, and glucanase, which are required for fungal growth and morphogenesis. This study revealed the maximum activity of functionally important proteins with phenol oxidase and lectin activities, and the emergence of additional laccases, tyrosinases, and lectins, which are typical of only this stage of morphogenesis and have a regulatory function in the development and formation of fruiting bodies.

The Extracts of Astragalus membranaceus Inhibit Melanogenesis through the ERK Signaling Pathway.

Melanin is a normal production protecting skin from environment-causing damage. Plants produce some agents in response to their environment. These agents could be applied in cosmetic production. Some Chinese herbals have immunomodulatory activities and modulate the symptoms of several diseases. Melanogenesis represents a complex group of conditions that are thought to be mediated through a complex network of regulatory processes. Previously, some studies found that the extracts of Astragalus membranaceus (PG2) regulated immunity and supported hematopoiesis. Herein, we want to determine the molecular mechanisms by which PG2 inhibits melanogenesis in B16F10 melanoma cells. The cellular melanin contents and expression of melanogenesis-related protein, including microphthalmia associated transcription factor (MITF) and tyrosinase were significantly reduced after PG2 treatment. Moreover, PG2 increased phosphorylation of ERK, without affecting phosphorylation of p38. These results suggested that PG2 as a new target in reducing hyperpigmentation through the ERK signal pathway. PG2 has potential for cosmetic usage in the future.

Melanogenesis in uveal melanoma cells: Effect of argan oil.

The mechanisms underlying cutaneous melanogenesis have been widely studied; however, very little is known about uveal melanogenesis. Melanin is normally produced by uveal melanocytes and gives the color to the iris. A derangement from this normal production may occur, for instance, by iatrogenic events, such as glaucoma therapy with prostaglandins that may enhance cutaneous and iris pigmentation. In this study, we investigated the mechanisms that regulate uveal melanogenesis in human uveal melanoma cells (92.1) and murine cutaneous melanoma cells (B16-F1). In the first part of the study, we compared the effects of known cutaneous pigmenting agents on the B16-F1 and 92.1 cells, showing an opposite response of the two cell lines. Subsequently, using argan oil, a known depigmenting agent for murine cutaneous melanoma cells, on 92.1 cells, we found that in these cells, it also functioned as an inhibitor of melanogenesis and tyrosinase expression. From a molecular perspective, treatment of the 92.1 cells with argan oil decreased melanogenesis-associated transcription factor (MITF) gene expression by inducing MITF phosphorylation at Ser73, thus leading to MITF ubiquitination and disposal. It also led to the downregulation of the extracellular signal-regulated kinase (ERK)1/2 and Akt pathways, also known to be involved in cutaneous melanogenesis, although with an opposing function. Taken together, our data indicate that: ⅰ) some differences exist in the regulation of melanogenesis between cutaneous and uveal melanoma cells; and ⅱ) argan oil exerts a depigmenting effect on 92.1 cells through its action on the ERK1/2 and Akt pathways.

The Importance of 11α-OH, 15-oxo, and 16-en Moieties of 11α-Hydroxy-15-oxo-kaur-16-en-19-oic Acid in Its Inhibitory Activity on Melanogenesis.

Cosmetic industries have an interest in exploring and developing materials that have the potential to regulate melanin synthesis in human skin. Although melanin protects the skin from ultraviolet irradiation, excess melanin can be undesirable, particularly on the face where spots or freckles are associated with an appearance of aging. In this study, we found that ent-11α-hydroxy-15-oxo-kaur-16-en-19-oic acid (11α-OH KA) in Pteris dispar Kunze strongly inhibited melanin synthesis by suppressing tyrosinase gene expression. The melanogenic transcription factor microphthalmia-associated transcription factor (MITF) is required for this suppression. However, 11α-OH KA did not modulate the expression level or activity of MITF. Structure-activity relationship analyses suggested that the 11α-OH, 15-oxo, and 16-en moieties of 11α-OH KA are essential for the suppression of melanin synthesis. On the other hand, the 19-COOH moiety is important for preventing cellular toxicity associated with 11α-OH KA and its related compounds. These results suggest that 11α-OH KA is an attractive target for potential use in the production of cosmetic items.

Gamma-Irradiated Luteolin Inhibits 3-Isobutyl-1-Methylxanthine-Induced Melanogenesis Through the Regulation of CREB/MITF, PI3K/Akt, and ERK Pathways in B16BL6 Melanoma Cells.

Luteolin was gamma irradiated at doses of 0, 15, 30, 50, 70, and 100 kGy. We observed that the luteolin peak decreased simultaneously with the appearance of new radiolytic peaks, using high-performance liquid chromatography (HPLC). The highest new radiolytic peak (GLM) of radiolytic product in gamma-irradiated luteolin was observed at a dose of 70 kGy, and the GLM was identified by nuclear magnetic resonance and high-performance-liquid-chromatography-quadrupole-time-of-flight (HPLC-Q-TOF) mass spectrometry. We examined whether 70 kGy gamma-irradiated luteolin has more effective anti-melanogenic effects than intact luteolin. Seventy kilograys of gamma-irradiated luteolin inhibited melanin synthesis and intracellular tyrosinase activity without cytotoxicity, whereas the intact luteolin-treated group did not show anti-melanogenic activity in 3-isobutyl-1-methylxanthine-stimulated B16BL6 melanoma cells. The expression of melanogenic enzymes, such as tyrosinase, tyrosinase-related protein (TRP)-1, and TRP-2, was decreased by 70 kGy gamma-irradiated luteolin treatment, owing to the suppression of microphthalamia-associated transcription factor and 3',5'-cyclic adenosine monophosphate (cAMP) response element binding protein. In addition, gamma-irradiated luteolin decreased the phosphorylation of phosphoinositide 3-kinase (PI3K)/Akt and extracellular regulated kinase (ERK). The anti-melanogenic effects of 70 kGy gamma-irradiated luteolin were attenuated by the treatment of two specific inhibitors (PD98059 and LY294002), and these results indicate that the anti-melanogenic effects were mediated by ERK and PI3K signaling pathways. Therefore, our findings suggest that gamma-irradiated luteolin can be a potential cosmeceutical agent for skin whitening.