Depigmenting Mechanisms of All-Trans Retinoic Acid and Retinol on B16 Melanoma Cells

Peptide and peptidomimetic tyrosinase inhibitors

Melanin, which is produced by melanocytes and spread over keratinocytes, is responsible for human skin browning. There are several processes involved in melanogenesis, mostly prompted by enzymatic activities. Tyrosinase (TYR), a copper containing metalloenzyme, is considered the main actor in melanin production, as it catalyzes two crucial steps that modify tyrosine residues in dopaquinone. For this reason, TYR inhibition has been exploited as a possible mechanism of modulation of hyper melanogenesis. There are various types of molecules used to block TYR activity, principally used as skin whitening agents in cosmetic products, e.g., tretinoin, hydroquinone, azelaic acid, kojic acid, arbutin and peptides. Peptides are highly valued for their versatile nature, making them promising candidates for various functions. Their specificity often leads to excellent safety, tolerability, and efficacy in humans, which can be considered their primary advantage over traditional small molecules. There are several examples of tyrosinase inhibitor peptides (TIPs) operating as possible hypo-pigmenting agents, which can be classified according to their origin: natural, hybrid or synthetically produced. Moreover, the possibility of variating their backbones, introducing non-canonical amino acids or modifying one or more peptide bond(s), to obtain peptidomimetic molecules, is an added value to avoid or delay proteolytic activity, while the possibility of conjugation with other bioactive peptides or organic moieties can bring other specific activity leading to dual-functional peptides.

Treatment of Periorbital Vascularity, Erythema, and Hyperpigmentation

Periorbital hyperpigmentation (POH) is a common aesthetic concern that impacts patients' emotional well-being and quality of life. POH can be difficult to manage as the etiology is often multifactorial or difficult to elucidate. An understanding of different contributing factors and ability to classify hyperpigmentation can aid in the management of POH. Classification of POH is divided into pigmented, vascular, structural, and mixed subtypes. A wide array of treatment options has been proposed belying the challenges inherent to improving POH. Modalities vary from topical therapies, chemical peels, dermal fillers, and lasers, to surgical intervention. Because POH can be multifactorial, successful management of POH will depend on elucidating the etiology and often requires a combination of therapies.

TMT-Based Quantitative Proteomic and Physiological Analyses on Serums of Chinese Patients with Active Vitiligo

Purpose

Vitiligo is an acquired depigmented skin disorder. Though genetic background, autoimmune dysregulation, and oxidative stress were reported involved in the development of vitiligo, the exact pathogenesis remains largely unknown. This study aimed to investigate potential functional proteins, pathways, and serum biomarkers involved in active vitiligo.

Patients and Methods

Tandem Mass Tags (TMT) method was used to determine differentially expressed proteins (DEPs) in serum samples between 11 active vitiligo patients and 7 healthy controls of Chinese Han population.

Results

A total of 31 DEPs were identified (P < 0.05, fold change >1.2), with 21 proteins upregulated and 10 proteins downregulated in the vitiligo group. DEPs were enriched in GO terms such as "extracellular exosome" and "immunoglobulin receptor binding", as well as KEGG pathways including "cysteine and methionine metabolism" and other immune-related pathways. Furthermore, ALDH1A1 and EEF1G achieved areas under receiver-operating characteristic (ROC) curve of 0.9221 and 0.8571, respectively. The expression levels of these 2 proteins were validated in another active vitiligo patient group.

Conclusion

Our research provided novel insight into serum proteomic profile for vitiligo patients, detecting ALDH1A1 and EEF1G as potential biomarkers for active vitiligo and therapeutic intervention. Our work also detected several DEPs and associated pathways in the serum of active vitiligo patients, reinforcing the roles of retinoic acid and exosome processes in vitiligo pathogenesis.

All-trans retinoic acid modulates pigmentation, neuroretinal maturation, and corneal transparency in human multiocular organoids

BACKGROUND

All-trans retinoic acid (ATRA) plays an essential role during human eye development, being temporally and spatially adjusted to create gradient concentrations that guide embryonic anterior and posterior axis formation of the eye. Perturbations in ATRA signaling can result in severe ocular developmental diseases. Although it is known that ATRA is essential for correct eye formation, how ATRA influences the different ocular tissues during the embryonic development of the human eye is still not well studied. Here, we investigated the effects of ATRA on the differentiation and the maturation of human ocular tissues using an in vitro model of human-induced pluripotent stem cells-derived multiocular organoids.

METHODS

Multiocular organoids, consisting of the retina, retinal pigment epithelium (RPE), and cornea, were cultured in a medium containing low (500 nM) or high (10 µM) ATRA concentrations for 60 or 90 days. Furthermore, retinal organoids were cultured with taurine and T3 to further study photoreceptor modulation during maturation. Histology, immunochemistry, qPCR, and western blot were used to study gene and protein differential expression between groups.

RESULTS

High ATRA levels promote the transparency of corneal organoids and the neuroretinal development in retinal organoids. However, the same high ATRA levels decreased the pigmentation levels of RPE organoids and, in long-term cultures, inhibited the maturation of photoreceptors. By contrast, low ATRA levels enhanced the pigmentation of RPE organoids, induced the opacity of corneal organoids-due to an increase in collagen type IV in the stroma- and allowed the maturation of photoreceptors in retinal organoids. Moreover, T3 promoted rod photoreceptor maturation, whereas taurine promoted red/green cone photoreceptors.

CONCLUSION

ATRA can modulate corneal epithelial integrity and transparency, photoreceptor development and maturation, and the pigmentation of RPE cells in a dose-dependent manner. These experiments revealed the high relevance of ATRA during ocular tissue development and its use as a potential new strategy to better modulate the development and maturation of ocular tissue through temporal and spatial control of ATRA signaling.

By-product of Korean liquor fermented by Saccharomyces cerevisiae exhibits skin whitening activity

Herein, the skin whitening effect of the fermentation residue of Saccharomyces cerevisiae was investigated. The fermentation residue showed radical scavenging activity and attenuated tyrosinase activity. Furthermore, the fermentation residue of S. cerevisiae significantly suppressed melanin generation in B16F10 cells. Interestingly, the sample-containing formulation exhibited increased skin whitening activity compared with that by the control formulation in a clinical study. Notably, the endogenous tyrosinase expression was not altered by the fermentation residue of S. cerevisiae; however, the enzymatic activity of tyrosinase was inhibited. Furthermore, the sample did not change TRP1 and TRP2 expression in B16F10 cells. Thus, the fermentation residue of S. cerevisiae was assumed to directly suppress the tyrosinase enzyme. It was confirmed that the fermentation residue of S. cerevisiae was a competitive inhibitor of tyrosinase. Taken together, the fermentation residue of S. cerevisiae could be a novel skin whitening agent originating from the traditional Korean liquor production process.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10068-022-01062-7.

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.

Sapindus mukorossiSeed Oil Changes Tyrosinase Activity of α-MSH-Induced B16F10 Cells Via the Antimelanogenesic Effect of Eicosenoic Acid

Melanogenesis is a complex process that can lead to pigmentation defects. Various chemical skin-lightening products have been developed to treat pigmentation disorders. However, these chemical products can cause harmful adverse effects. Therefore, the development of safer, natural bleaching ingredients is a trend for sustainability. It has been reported that unsaturated fatty acids exhibit significant antimelanogenic effects. Sapindus mukorossi seed oils contain abundant unsaturated fatty acids; however, these have not yet been investigated for beneficial effects on skin tone evenness. In this study, we tested the possibility of using S. mukorossi oil for the treatment of hyperpigmentation in an in vitro model. Free fatty acid compositions and β-sitosterol were determined by gas chromatography-mass spectrometry and high-pressure liquid chromatography, respectively. The effect of S. mukorossi oil on melanoma B16F10 cell viability was detected using the 3-(4,5-dimethylthiazol-2-yl)- 2,5-diphenyl-tetrazolium bromide assay. The inhibitive effects of fatty acids and β-sitosterol in S. mukorossi oil on α-melanocyte-stimulating hormone (MSH)-induced melanogenesis was evaluated by detecting melanin formation and tyrosinase activity. Our results showed that S. mukorossi oil produced no significant cytotoxicity in B16F10 cells at various concentrations compared with the control group. The enhancement of melanin formation induced by α-MSH was reduced by S. mukorossi oil. We also found that the primary fatty acid contributing to the antimelanogenesis effect was eicosenoic acid. These results suggest that S. mukorossi seed oil can effectively inhibit melanogenesis and has the potential for future development as a de-hyperpigmentation product within a waste utilization context.

Pleurochrysis carterae Hot-Water Extract Inhibits Melanogenesis in Murine Melanoma Cells

In this study, we examined the effect of a hot-water extract of coccolithophore Pleurochrysis carterae on melanogenesis in B16F1 and B16F10 melanoma cells. P. carterae extract inhibited the α-melanocyte-stimulating hormone (α-MSH)-enhanced melanin synthesis in B16F1 melanoma cells. P. carterae also inhibited unstimulated melanin synthesis in B16F10 melanoma cells. Western blotting showed that the P. carterae extract inhibited tyrosinase and microphthalmia-associated transcription factor (MITF) in a dose-dependent manner. The reporter assay also revealed a decline in the tyrosinase promoter activity in the presence of P. carterae extract. Furthermore, quantitative real-time RT-PCR analysis showed that P. carterae extract downregulated the mRNA levels of tyrosinase and MITF. Finally, our study demonstrated that the hot-water extract of P. carterae inhibits melanin synthesis via the down-regulation of MITF mRNA level. Our findings indicate that P. carterae extract could be a possible cosmetic ingredient.

Discovery of new depigmenting compounds and their efficacy to treat hyperpigmentation: Evidence from in vitro study

Human skin pigmentation is a result of constitutive and facultative pigmentation. Facultative pigmentation is frequently stimulated by UV radiation, pharmacologic drugs, and hormones whereby leads to the development of abnormal skin hyperpigmentation. To date, many state-of-art depigmenting compounds have been studied using in vitro model to treat hyperpigmentation problems for cosmetic dermatological applications; little attention has been made to compare the effectiveness of these depigmenting compounds and their mode of actions. In this present article, new and recent depigmenting compounds, their melanogenic pathway targets, and modes of action are reviewed. This article compares the effectiveness of these new depigmenting compounds to modulate several melanogenesis-regulatory enzymes and proteins such as tyrosinase (TYR), TYR-related protein-1 (TRP1), TYR-related protein-2 (TRP2), microphthalmia-associated transcription factor (MITF), extracellular signal-regulated kinase (ERK) and N-terminal kinases (JNK) and mitogen-activated protein kinase p38 (p38 MAPK). Other evidences from in vitro assays such as inhibition on melanosomal transfer, proteasomes, nitric oxide, and inflammation-induced melanogenesis are also highlighted. This article also reviews analytical techniques in different assays performed using in vitro model as well as their advantages and limitations. This article also provides an insight on recent finding and re-examination of some protocols as well as their effectiveness and reliability in the evaluation of depigmenting compounds. Evidence and support from related patents are also incorporated in this present article to give an overview on current patented technology, latest trends, and intellectual values of some depigmenting compounds and protocols, which are rarely highlighted in the literatures.

Peroxisome proliferator-activated receptor α (PPARα) contributes to control of melanogenesis in B16 F10 melanoma cells

Recent studies revealed the cooperation between peroxisome proliferator-activated receptor gamma (PPARγ) and α-MSH signaling, which results in enhanced melanogenesis in melanocytes and melanoma cells. However, the agonists of PPARα, such as fenofibrate, exert depigmenting effect. Therefore, we aimed to check how the PPARα expression level affects the antimelanogenic activity of fenofibrate and whether PPARα modulates melanogenesis independently of its agonist. To answer these questions, we used three B16 F10-derived cell lines, which varied in the PPARα expression level and were developed by stable transfection with plasmids driving shRNA-based PPARα silencing or overexpression of PPARα-emerald GFP fusion protein. Melanin contents were assessed with electron paramagnetic resonance spectroscopy along with color component image analysis-a novel approach to pigment content characteristics in melanoma cells. B16 F10 wt and Ctrl shRNA lines showed intermediate pigmentation, whereas the pigmentation of the B16 F10-derived cell lines was inversely correlated with the PPARα expression level. We observed that cells overexpressing PPARα were almost amelanotic and cells with reduced PPARα protein level were heavily melanized. Furthermore, fenofibrate down-regulated the melanogenic apparatus (MITF, tyrosinase, and tyrosinase-related proteins) in the cells with the regular PPARα expression level resulting in their visibly lower total melanin content in all the cell lines. From these observations, we conclude that fenofibrate works as a strong depigmenting agent, which acts independently of PPARα, but in an additive fashion. Our results also indicate that alterations in PGC-1a acetylation and expression level might contribute to the regulation of melanogenesis by PPARα and fenofibrate.

2-Ethoxybenzamide stimulates melanin synthesis in B16F1 melanoma cells via the CREB signaling pathway

Non-steroidal anti-inflammatory drugs are frequently used for the treatment of inflammation, pain, and fever. In this study, we found that 2-ethoxybenzamide (ETZ) significantly enhanced melanin synthesis in B16F1 melanoma cells, and also induced melanosome formation. Therefore, we investigated the mechanism by which ETZ up-regulated melanin synthesis. Western blot analysis demonstrated that ETZ increased melanogenic protein levels, except that for TRP-2. Moreover, semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) and real-time RT-PCR analyses showed that ETZ enhanced the mRNA levels of melanogenic genes, including microphthalmia-associated transcription factor and melanocortin 1 receptor. We also observed phosphorylation of cAMP response element-binding protein (CREB) following ETZ treatment. However, ETZ did not affect intracellular cAMP levels. ERK was also activated by ETZ treatment, and melanin content was enhanced upon treatment with the specific ERK inhibitor PD98059. Together, our results indicate that ETZ induces melanin synthesis via CREB phosphorylation.

Dual effects of acetylsalicylic acid on ERK signaling and Mitf transcription lead to inhibition of melanogenesis

Acetylsalicylic acid (ASA) is widely used as an analgesic/antipyretic drug. It exhibits a wide range of biological effects, including preventative effects against heart attack and stroke, and the induction of apoptosis in various cancer cells. We previously found that ASA inhibits melanogenesis in B16 melanoma cells. However, the mechanisms of how ASA down-regulates melanin synthesis remain unclear. Here, we investigated the effect of ASA on melanogenic pathways, such as extracellular signal-regulated kinase (ERK) and microphthalmia-associated transcription factor (Mitf) transcription. ASA significantly inhibited melanin synthesis in a dose-dependent manner without oxidative stress and cell death. Semi-quantitative reverse transcription-polymerase chain reaction analysis showed that the inhibitory effect of ASA might be due to the inhibition of Mitf gene transcription. Interestingly, ASA also induced ERK phosphorylation. Additionally, treatment with PD98059, a specific ERK phosphorylation inhibitor, abolished the anti-melanogenic effect of ASA. These results suggest that the depigmenting effect of ASA results from down-regulation of Mitf, which is induced by both the induction of ERK phosphorylation and the inhibition of Mitf transcription.

Hair dyes resorcinol and lawsone reduce production of melanin in melanoma cells by tyrosinase activity inhibition and decreasing tyrosinase and microphthalmia-associated transcription factor (MITF) expression

Hair coloring products are one of the most important cosmetics for modern people; there are three major types of hair dyes, including the temporary, semi-permanent and permanent hair dyes. The selected hair dyes (such as ammonium persulfate, sodium persulfate, resorcinol and lawsone) are the important components for hair coloring products. Therefore, we analyzed the effects of these compounds on melanogenesis in B16-F10 melanoma cells. The results proved that hair dyes resorcinol and lawsone can reduce the production of melanin. The results also confirmed that resorcinol and lawsone inhibit mushroom and cellular tyrosinase activities in vitro. Resorcinol and lawsone can also downregulate the protein levels of tyrosinase and microphthalmia-associated transcription factor (MITF) in B16-F10 cells. Thus, we suggest that frequent use of hair dyes may have the risk of reducing natural melanin production in hair follicles. Moreover, resorcinol and lawsone may also be used as hypopigmenting agents to food, agricultural and cosmetic industry in the future.

Rationale of using hypopigmenting drugs and their clinical application in melasma

Among the pigmentary disorders, melasma is the prototype disorder characterized by hyperpigmentation. Although, conventionally, triple combination creams are used, there is a need for alternatives to hydroquinone as the drug has restrictions on its widespread use. This needs an understanding of the steps involved in the melanogenesis and the drugs that inhibit the key steps. The data on in vitro inhibition need to be then translated into clinical in vivo results, before a rationale compounded fixed drug preparation is marketed that inhibits the major steps in the pigmentation pathway. There is also a need to look for drugs that are superior to hydroquinone, as only then will they have a meaningful clinical utility. For now, a few drugs like deoxyarbutin, ellagic acid, dioic acid, n-butylresorcinol and azelaic acid have such properties in clinical trials, while metformin is a recent addition.

Inhibition of peroxisome proliferator-activated receptor gamma prevents the melanogenesis in murine B16/F10 melanoma cells

The purpose of this study was to investigate if PPARγ plays a role in the melanogenesis. B16/F10 cells were divided into five groups: control, melanin stimulating hormone (α-MSH), α-MSH+retinol, α-MSH+GW9662 (PPARγ antagonist), and GW9662. Cells in the control group were cultured in the Dulbecco's modified Eagle's medium (DMEM) for 48 hrs. To initiate the melanogenesis, cells in all α-MSH groups were cultured in medium containing α-MSH (10 nM) for 48 hrs. Cells were treated simultaneously with retinol (5 μM) in the α-MSH+retinol group. Instead of retinol, GW9662 (10 μM) was cocultured in the α-MSH+GW9662 group. Cells in the final group were cultured in the DMEM with GW9662. All the analyses were carried out 48 hours after treatments. The α-MSH was able to increase cell number, melanin production, and the activity of tyrosinase, the limiting enzyme in melanogenesis. These α-MSH-induced changes were prevented either by retinol or by GW9662. Further analyses of the activities of antioxidant enzymes including glutathione, catalase, and the superoxide dismutase (SOD) showed that α-MSH treatment raised the activity of SOD which was dependent on PPARγ level. According to our results, the α-MSH-induced melanogenesis was PPARγ dependent, which also modulated the expression of SOD.

Fermented broth in tyrosinase- and melanogenesis inhibition

Fermented broth has a long history of applications in the food, pharmaceutical and cosmetic industries. Recently, the use of fermented broth in skin care products is in ascendance. This review investigates the efficacy of fermented broth in inhibiting tyrosinase and melanogenesis. Possible active ingredients and hypopigmentation mechanisms of fermented broth are discussed, and potential applications of fermented broth in the cosmetic industry are also addressed.

9-cis retinoic acid is the ALDH1A1 product that stimulates melanogenesis

Aldehyde dehydrogenase 1A1 (ALDH1A1), an enzyme that catalyses the conversion of lipid aldehydes to lipid carboxylic acids, plays pleiotropic roles in UV-radiation resistance, melanogenesis and stem cell maintenance. In this study, a combination of RNAi and pharmacologic approaches were used to determine which ALDH1A1 substrates and products regulate melanogenesis. Initial studies revealed that neither the UV-induced lipid aldehyde 4-hydroxy-2-nonenal nor the ALDH1A1 product all-trans retinoic acid appreciably induced melanogenesis. In contrast, both the ALDH1A1 substrate 9-cis retinal and its corresponding product 9-cis retinoic acid potently induced the accumulation of MITF mRNA, Tyrosinase mRNA and melanin. ALDH1A1 depletion inhibited the ability of 9-cis retinal but not 9-cis retinoic acid to stimulate melanogenesis, indicating that ALDH1A1 regulates melanogenesis by catalysing the conversion of 9-cis retinal to 9-cis retinoic acid. The addition of potent ALDH1A inhibitors (cyanamide or Angeli's salt) suppressed Tyrosinase and MITF mRNA accumulation in vitro and also melanin accumulation in skin equivalents, suggesting that 9-cis retinoids regulate melanogenesis in the intact epidermis. Taken together, these studies not only identify cyanamide as a potential novel treatment for hyperpigmentary disorders, but also identify 9-cis retinoic acid as a pigment stimulatory agent that may have clinical utility in the treatment of hypopigmentary disorders, such as vitiligo.

Identification of prognostic genes for recurrent risk prediction in triple negative breast cancer patients in Taiwan

Discrepancies in the prognosis of triple negative breast cancer exist between Caucasian and Asian populations. Yet, the gene signature of triple negative breast cancer specifically for Asians has not become available. Therefore, the purpose of this study is to construct a prediction model for recurrence of triple negative breast cancer in Taiwanese patients. Whole genome expression profiling of breast cancers from 185 patients in Taiwan from 1995 to 2008 was performed, and the results were compared to the previously published literature to detect differences between Asian and Western patients. Pathway analysis and Cox proportional hazard models were applied to construct a prediction model for the recurrence of triple negative breast cancer. Hierarchical cluster analysis showed that triple negative breast cancers from different races were in separate sub-clusters but grouped in a bigger cluster. Two pathways, cAMP-mediated signaling and ephrin receptor signaling, were significantly associated with the recurrence of triple negative breast cancer. After using stepwise model selection from the combination of the initial filtered genes, we developed a prediction model based on the genes SLC22A23, PRKAG3, DPEP3, MORC2, GRB7, and FAM43A. The model had 91.7% accuracy, 81.8% sensitivity, and 94.6% specificity under leave-one-out support vector regression. In this study, we identified pathways related to triple negative breast cancer and developed a model to predict its recurrence. These results could be used for assisting with clinical prognosis and warrant further investigation into the possibility of targeted therapy of triple negative breast cancer in Taiwanese patients.

The inhibitory effect of non-steroidal anti-inflammatory drugs (NSAIDs) on the monophenolase and diphenolase activities of mushroom tyrosinase

In the present work, we investigated the effect of non-steroidal anti-inflammatory drugs (NSAIDs) on the monophenolase and diphenolase activity of mushroom tyrosinase. The results showed that diflunisal and indomethacin inhibited both monophenolase and diphenolase activity. For monophenolase activity, the lag time was extended in the presence of diflunisal. In the presence of indomethacin, the lag time did not change. IC₅₀ values of monophenolase activity were estimated to be 0.112 mM (diflunisal) and 1.78 mM (indomethacin). Kinetic studies of monophenolase activity revealed that both diflunisal and indomethacin were non-competitive inhibitors. For diphenolase activity, IC₅₀ values were estimated to be 0.197 mM (diflunisal) and 0.509 mM (indomethacin). Diflunisal and indomethacin were also found to be non-competitive diphenolase inhibitors.

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.

Anti-pigmentary activity of fucoxanthin and its influence on skin mRNA expression of melanogenic molecules

OBJECTIVES

Carotenoids and retinoic acid derivatives are topically applied for sun-protective and whitening purposes. Fucoxanthin is a carotenoid derived from edible sea algae, but its effect on melanogenesis has not been established. Therefore, we examined the effect of fucoxanthin on melanogenesis.

METHODS

Inhibitory effects on tyrosinase activity, melanin formation in B16 melanoma and skin pigmentation in UVB-irradiated guinea-pigs were evaluated. To elucidate the action of fucoxanthin on melanogenesis, its effect on skin melanogenic mRNA expression was evaluated in UVB-irradiated mice. Fucoxanthin was given topically or orally to mice once a day and UVB irradiation was applied for 14 days. The effect of fucoxanthin on skin melanogenic mRNA expression was evaluated by real time reverse transcription polymerase chain reaction.

KEY FINDINGS

Fucoxanthin inhibited tyrosinase activity, melanogenesis in melanoma and UVB-induced skin pigmentation. Topical application of fucoxanthin (1%) significantly suppressed mRNA expression of cyclooxygenase (COX)-2, endothelin receptor A, p75 neurotrophin receptor (NTR), prostaglandin E receptor 1 (EP1), melanocortin 1 receptor (MC1R) and tyrosinase-related protein 1. The suppression of p75NTR, EP1 and MC1R expressions was observed at 0.01% application. Also, oral application of fucoxanthin (10 mg/kg) significantly suppressed expression of COX-2, p75NTR, EP1 and MC1R.

CONCLUSIONS

These results suggest that fucoxanthin exhibits anti-pigmentary activity by topical or oral application in UVB-induced melanogenesis. This effect of fucoxanthin may be due to suppression of prostaglandin (PG) E(2) synthesis and melanogenic stimulant receptors (neurotrophin, PGE(2) and melanocyte stimulating hormone expression).

Effects of vitamin C vs. multivitamin on melanogenesis: comparative study in vitro and in vivo

BACKGROUND

Vitamin C has been used for the treatment of hyperpigmented diseases. However, there is no study available on hypopigmenting effect of multivitamin.

OBJECTIVES

To investigate the inhibitory effects of multivitamin and vitamin C on melanogenesis.

METHODS

We assessed the effect of multivitamin and vitamin C on cell viability, melanogenesis, and mushroom tyrosinase. The antioxidant activity of multivitamin and vitamin C was measured. We performed the Western blot analysis to study the effect of multivitamin and vitamin C on the expression of tyrosinase, microphthalmia-associated transcription factor (MITF), extracellular signal-regulated kinase (ERK), and Akt/protein kinase B. In a clinical trial, 20 melasma patients were treated with split face iontophoresis using either multivitamin or vitamin C. We evaluated the hypopigmenting effects of multivitamin and vitamin C through colorimetric measurement.

RESULTS

Both vitamin C and multivitamin inhibited melanogenesis with low cytotoxicity. Multivitamin reduced melanin contents greater than vitamin C. However, the effects of vitamin C are greater than those of multivitamin on mushroom tyrosinase inhibition and antioxidation. In the Western blot, the reduced tyrosinase expression and MITF level were observed only in multivitamin-treated group, and not in vitamin C-treated group. No changes of ERK and Akt activation were observed in both multivitamin and vitamin C-treated groups. After 12 weeks of treatment with iontophoresis, both multivitamin and vitamin C were effective for melasma.

CONCLUSIONS

Multivitamin has shown more anti-melanogenic effect than vitamin C via the downregulation of MITF.

Current research and development of chemotherapeutic agents for melanoma

Cutaneous malignant melanoma is the most lethal form of skin cancer and an increasingly common disease worldwide. It remains one of the most treatment-refractory malignancies. The current treatment options for patients with metastatic melanoma are limited and in most cases non-curative. This review focuses on conventional chemotherapeutic drugs for melanoma treatment, by a single or combinational agent approach, but also summarizes some potential novel phytoagents discovered from dietary vegetables or traditional herbal medicines as alternative options or future medicine for melanoma prevention. We explore the mode of actions of these natural phytoagents against metastatic melanoma.