Increased Tyrosinase Activity Research Articles

Low-concentration imiquimod treatment promotes enhanced skin barrier functions through epidermal melanization reaction regulation.

The primary function of the skin is to form a mechanical, permeability, antimicrobial, and ultraviolet radiation barrier, which is essential for maintaining physiological homeostasis. Our previous studies demonstrated that cutaneous pigmentation could promote skin barrier function in addition to providing anti-ultraviolet irradiation defense. The present study aimed to develop a new regimen that enhances skin barrier function by regulating skin pigmentation using low-concentration imiquimod. Results showed that topical application of low-concentration imiquimod effectively induced skin hyperpigmentation in the dorsal skin and external ear of mice without inducing inflammatory cell infiltration. An in vitro study also revealed that low-concentration imiquimod did not induce any cytotoxic effects on melanoma cells but triggered excessive melanin synthesis. In coculture systems, low-concentration imiquimod was noted to increase tyrosinase activity in a broader cellular context, revealing the potential role of neighboring cells in melanin production. The next-generation sequencing result indicated that PKCη and Dnm3 might regulate melanin synthesis and release during imiquimod treatment. Overall, our study presents new insights into the regulation of melanin production by low-concentration imiquimod, both in a mice model and cultured cells. Furthermore, our study highlights the potential benefits of imiquimod in promoting melanin synthesis without causing skin disruptions or inducing inflammation, validating its potential to serve as a method for enhancing skin barrier functions by regulating the epidermal melanization reaction.

Putrescine Upregulates Melanogenesis Through Modulation of MITF Transcription Factor in B16F1 Mouse Melanoma Cells.

Ageing is a biochemical, metabolic and genetic physiological phenomenon. The suppression of melanin biosynthesis, evident in the greying of the hair, is a hallmark of ageing resulting from translation failure, reduced enzyme activity and cellular senescence. Putrescine, the smallest member of the polyamine family and an organic chemical, is present in living mammalian cells and plays a crucial role in regulating skin melanogenesis. Therefore, the purpose of this study is to explore the effect of putrescine on the signalling pathways of melanogenesis in melanoma cells. Melanin production capacity of putrescine was analysed using a tyrosinase activity assay. To assess the cell viability of B16F1 cells exposed to putrescine, a tetrazolium dye MTT assay was performed. The effect of putrescine on melanin synthesis in the presence of H2O2 was evaluated using various in vitro assays in B16F1 cells. The effect of putrescine on melanin production in B16F1 cells was determined using a specific melanin production assay. Gene expression was analysed using real-time polymerase chain reaction (RT-PCR). Furthermore, the effect of putrescine on the expression of proteins related to melanin production in the cells treated with H2O2 was analysed by immunofluorescence and Western blot analysis. Putrescine increased tyrosinase activity and showed no cytotoxicity in B16F1 cells. In addition, putrescine effectively scavenged H2O2, as shown by the reduction of intracellular H2O2 amounts in 2',7'-dichlorofluorescin diacetate analysis, and promoted melanin production in living cells. The stimulation of melanogenesis by putrescine was attributed to the increased expression of Mitf, Tyr, Trp-1 and Trp-2 genes. Immunofluorescence assays revealed that putrescine enhanced the expression of proteins associated with melanogenesis and upregulated TYR, TRP-1 and TRP-2 via the microphthalmia-associated transcription factor (MITF) and increased the expression of methionine sulfoxide reductases A (MSRA) and B (MSRB) in the cells treated with H2O2, effectively promoting melanogenesis. These results suggest that putrescine can be used to stimulate melanin synthesis. This is the first study to investigate the effect of putrescine on the signalling pathways of melanogenesis in B16F1 melanoma cells. The results confirm that putrescine can promote melanogenesis through the expression of TYR, TRP-1 and TRP-2 via the MITF in cells treated with H2O2. Putrescine can be used exclusively as a cosmetic product to prevent premature greying of hair.

Integrative pharmacology reveals the mechanisms of Erzhi pills, A traditional Chinese formulation, stimulating melanogenesis

Ethnopharmacological relevanceErzhi pills (EZP), a traditional Chinese medicine formula prescribed for the treatment of vitiligo, has shown promising efficacy. However, the oral bioactive components and mechanisms underlying the promotion of melanogenesis by EZP remain unclear. Aim of the studyThis study aimed to investigate the pharmacological basis and mechanism of EZP in promoting melanogenesis. Materials and methodsUHPLC-TOF-MS analysis was used to identify absorbed phytochemicals in serum after oral administration of EZP. Network pharmacology methods were used to predict potential targets and pathways involved in the melanogenic activity of EZP, resulting in the construction of a “compound-target-pathway” network. Zebrafish and B16F10 cells were used to evaluate the effects of EZP on tyrosinase activity and melanin content. Western blot and ELISA analyses were used to validate the effects of EZP on melanogenesis-related proteins, including MITF, TYR, CREB, p-CREB, and cAMP. ResultsUHPLC-TOF-MS analysis identified 36 compounds derived from EZP in serum samples. Network pharmacology predictions revealed 89 target proteins associated with the identified compounds and closely related to vitiligo. GO and KEGG analyses indicated the involvement of the cAMP/PKA signaling pathway in the promotion of melanogenesis by EZP. Experimental results showed that EZP increased tyrosinase activity and melanin content in zebrafish and B16F10 cells without inducing toxicity. Western blot and ELISA results suggested that the melanogenic effect of EZP may be related to the activation of the cAMP/PKA signaling pathway. These results confirm the feasibility of combining serum pharmacological and network pharmacological approaches. ConclusionsEZP have the potential to increase tyrosinase activity and melanin content in zebrafish and cells possibly through activation of the cAMP/PKA pathway.

Silencing of Amylomyces rouxii aspartic II protease by siRNA to increase tyrosinase activity

Amylomyces rouxii is a zygomycete that produces extracellular protease and tyrosinase. The tyrosinase activity is negatively regulated by the proteases and, which attempts to purify the tyrosinase (tyr) enzyme that has been hampered by the presence of a protease that co-purified with it. In this work we identified genes encoding aspartic protease II (aspII) and VI of A. rouxii. Using an RNAi strategy based on the generation of a siRNA by transcription from two opposite-orientated promoters, the expression of these two proteases was silenced, showing that this molecular tool is suitable for gene silencing in Amylomyces. The transformant strains showed a significant attenuation of the transcripts (determined by RT-qPCR), with respective inhibition of the protease activity. In the case of aspII, inhibition was in the range of 43–90 % in different transformants, which correlated well with up to a five-fold increase in tyr activity with respect to the wild type and control strains. In contrast, silencing of aspVI caused a 43-65 % decrease in protease activity but had no significant effect on the tyr activity. The results show that aspII has a negative effect on tyr activity, and that the silencing of this protease is important to obtain strains with high levels of tyr activity.

Isolation of Tyrosinase Producing Bacteria from Rhizosphere Soil Samples

The present study is based on the isolation and identification of the bacteria producing tyrosinase enzyme which play an important role in production of L-DOPA amino acid which is used to treat Parkinson’s disease. In the study, 42 rhizosphere soil samples were collected from Akola and Amravati district, out of which 15 isolates were found to be tyrosinase enzyme producers when screened on tyrosine agar medium. Two isolates NT and ST showed most prominent tyrosinase production which latter checked for the effect of parameters on tyrosinase activity. Results revealed that tyrosinase activity was optimum at temperature range 37℃ - 42°C, pH 6 for NT isolate and pH 9 for ST isolate and time course 72 hours. Further effect of nitrogen sources showed prominent increase in tyrosinase activity after addition of 1% sodium and potassium nitrate while addition of carbon sources did not show any remarkable increase in tyrosinase activity.

Mechanisms of antioxidants in the treatment of vitiligo in vivo: a systematic review

Vitiligo is characterized by skin discoloration in different body regions, and its prevalence in the world population can reach 1%. Its cause is still undefined but possibly related to biochemical, environmental, immunological, and genetic events. In addition, individuals with vitiligo present electrolyte disturbances in the melanocytes, and it has been one of the targets of studies for treating this pathology. This systematic review aimed to gather and evaluate in vivo studies that described the mechanism of action of antioxidants in vitiligo. PubMed, Web of Science, Embase, Science Direct, LILACS, Open Grey and Google Scholar were used as research sources. The search included all articles up to October 16, 2021, with no start date restrictions. The search yielded 390 articles, and 7 of these were selected according to the inclusion criteria. The compounds studied in the articles selected for this review were curcumin, Cold Atmospheric Plasma, butin, galangin, 2',3,4,4'-tetrahydrochalcone and its derivatives, 6-benzylaminopurine, piperine, chrysin, kaempferol, scopoletin, vitamin D3, caffeic acid, and luteolin. The results showed that the main mechanisms of action of antioxidants in the treatment of vitiligo are the increase in tyrosinase activity by increasing the synthesis of TYR and TRP-1, the positive regulation of the number of epidermal cells, the redox balance, activation and regulation of MITF, and malondialdehyde and cholinesterase/acetylcholinesterase content. Thus, these pathways can be considered targets for evaluating different antioxidant compounds to act in treating vitiligo.

640 Exploring the synergic effects of a plant and a peptide on hair follicle pigmentation

Canities is an age-linked loss of bulb melanocyte and hair follicle (HF) pigmentation. Canities can significantly alter the physical appearance of a person and negatively impact their well-being, which drives the search and demand for new anti-greying agents. αMSH is pro-pigmentary hormone of the melanocortin family, which stimulates melanogenesis through its target receptor, MC1. GreyverseTM (Gv) is a biomimetic synthetic peptide derived to mimic αMSH and is an established promoter of HF melanogenesis with redox properties. Preliminary studies revealed that cotreatment of Gv and Paeonia Suffruticosa root bark extract (PS) synergically induces mitochondrial E3 ligase (MITOL) and melanogenesis in human melanocytes in vitro. Thus, this study investigated the additive effects of PS and Gv on hair pigmentation ex vivo. HFs were cultured in serum-free medium, supplemented with PS and/or Gv for 4 days, then assessed for protein expression and enzymatic changes associated to melanogenesis. Quantitative immune-histomorphometry revealed that PS and Gv cotreatment led to an additive increase in melanin content (p<0.05) that derived from a synergic increase in Gp100 expression (p<0.05), an increase in tyrosinase activity, and αMSH and TYRP expression within the hair follicle pigmentary unit. Taken together, PS and Gv showed synergic effects in promoting hair pigmentation, primarily through melanosome maturation. Thus, this combinational treatment deserves further pre-clinical and clinical exploration for the reversal of hair greying.

Advanced Glycation End Products Promote Melanogenesis by Activating NLRP3 Inflammasome in Human Dermal Fibroblasts

Advanced glycation end product (AGE) accumulation is significantly increased in the dermis of photoaged skin and plays crucial roles in photoaging. Although AGEs have been found to contribute to the yellowish discoloration of photoaged skin, their roles in photoaging-associated hyperpigmentation disorders have not been extensively studied. In this study, we observed that AGEs, NLRP3, and IL-18 were increased in the dermis of sun-exposed skin and lesions of melasma and solar lentigo and that dermal deposition of AGE was positively correlated with epidermal melanin levels. In addition, we found that AGE-BSA potently activated NLRP3 inflammasome and promoted IL-18 production and secretion in cultured fibroblasts, which was mediated by receptor for AGE/NF-κB pathway. Moreover, AGE-BSA significantly promoted melanogenesis by increasing tyrosinase activity and expression of microphthalmia-associated transcription factor and tyrosinase, which was dependent on NLRP3 inflammasome activation and IL-18 secretion in fibroblasts. Notably, AGE-collagen could activate NLRP3 inflammasome in fibroblasts and enhance melanogenesis. Furthermore, we found that IL-18 enhanced melanogenesis by binding to its receptor and activating p38 MAPK and extracellular signal‒regulated kinase 1/2 signaling pathways in melanocytes. Importantly, the promelanogenesis of AGE-BSA was verified in exvivo cultured skin and mouse models. These findings suggest that dermal AGEs stimulate melanogenesis and contribute to the development of photoaging-associated hyperpigmentation disorders.

Tinted Sunscreens: Consumer Preferences Based on Light, Medium, and Dark Skin Tones

Visible light (VL) has been shown to increase tyrosinase activity and induce immediate erythema in light-skinned individuals and long-lasting pigmentation in dark-skinned individuals. Tinted sunscreens (TSs) formulated with iron oxides (IOs) and/or pigmentary titanium dioxide (PTD) provide functional and cosmetic benefits and are a safe, effective, and convenient way to protect against both UV and high-energy VL. We conducted an analysis of over-the-counter TSs with the objective of investigating the factors that influence consumer preference when choosing TS depending on underlying skin tone. Descriptive data for each product were collected from an online supplier that provides reviewer information. The top 10 most helpful reviews were analyzed and coded by a consensus qualitative coding scheme, which included positive and negative descriptors in 5 major categories. Most products provided only one color shade, and tone incompatibility was the most commonly cited negative feature, with the vast majority of these comments being from consumers of dark skin tones. Top recommended products corresponded with increased shade options, indicating the dearth of shade diversity in products to be a potential area of improvement in tinted sunscreen options.

Development of piperine nanoemulsions: an alternative topical application for hypopigmentation

This study, it was aimed to develop a topical piperine nanoemulsion (P-NE) using an ultrasonic emulsification process to find an alternative treatment option for some hypopigmentation disorders such as vitiligo. Results showed that 150 mg piperine loaded NE with 1:2 oil phase to S mix ratio and manufactured with 20 min ultrasonication duration with the pre-emulsification step was the most durable formulation with a mean globule size of 216.00 ± 2.65, a PdI value of 0.094 ± 0.02 and a zeta potential value of −27.50 ± 2.48 mV. After three months of storage, the selected P-NE (coded as F3P2) remained kinetically stable without visual changes. This formulation displayed a sustained release pattern with a release of 81.92% ± 3.04% piperine after 72 h. According to our in vitro activity experiments, it was determined that the P-NE had no toxic effect including the dose of 5 mg/mL, and the highest P-NE formulation dose of 5 mg/mL increased tyrosinase activity by 32.77% ± 9.09% and melanogenesis activity by 34.90% ± 0.73%. In conclusion, it was demonstrated that the P-NE formulation may serve as a promising therapy for the efficient treatment of vitiligo. Moreover, P-NE formulation may also help in preventing irregular pigmentation and skin cancer, associated with the conventional treatment methods.

Development of Ultrasound-Assisted Extraction to Produce Skin-Whitening and Anti-Wrinkle Substances from Safflower Seed.

In this study, ultrasound-assisted extraction (UAE) was applied to extract bioactive substances with skin-whitening, anti-wrinkle, and antioxidant effects from safflower seeds, and the extraction conditions were optimized by a central composite design. The independent variables, including extraction time (5.0~55.0 min), extraction temperature (26.0~94.0 °C), and ethanol concentration (0.0~100%), were optimized to increase tyrosinase activity inhibitory (TAI), collagenase activity inhibitory (CAI), and radical scavenging activity (RSA), which are indicators of skin-whitening, anti-wrinkle, and antioxidant effects. An extraction time of 26.4 min, extraction temperature of 52.1 °C, and ethanol concentration of 50.7% were found to be optimum conditions of UAE, under which TAI, CAI, and RSA were 53.3%, 91.5%, and 27.7%, respectively. The extract produced by UAE was analyzed by LC-MS/MS, and maleic acid and levulinic acid were identified as the main substances. Therefore, UAE is evaluated as an effective process to extract skin-whitening, anti-wrinkle, and antioxidant substances from safflower seeds at lower temperatures and shorter extraction times compared to the conventional extraction methods. Overall, safflower seeds extract can be used as a material for value-added cosmetics, including maleic acid and levulinic acid, which have bioactive functions.

Synthesis and Melanogenesis Effect of 7,8-Dimethoxy-4-Methylcoumarin via MAPK Signaling-Mediated Microphthalmia-Associated Transcription Factor Upregulation

Tyrosinase ultimately controls the melanogenesis rate of the skin, and tanning and haircare products generally induce the activation of tyrosinase. Moreover, various enzymes, including tyrosinase, tyrosinase-related protein 1 (TRP1), and tyrosinase-related protein 2 (TRP2), mediate melanogenesis in which microphthalmia-associated transcription factor (MITF) is a master regulator. One coumarin family member 7,8-dihydroxy-4-methylcoumarin (DHMC) shows extensive biological activities with beneficial health effects; however, it also induces cytotoxicity and its melanogenic effect has not been reported yet. Therefore, we first synthesized DHMC derivatives via methylation to obtain 7,8-dimethoxy-4-methylcoumairn (DMMC), and investigated the pro- or anti-melanogenic effects of DHMC and DMMC in B16-F10 melanoma cells as well as the underlying mechanism. DHMC showed cytotoxicity at all tested concentrations, whereas DMMC did not reduce cell viability, even at the high concentration. DMMC also drives the significant increase in intracellular melanin and tyrosinase activity. Moreover, DMMC induced MITF expression by significantly increasing tyrosinase activity, which activates the gene expression of TRP1 and TRP2. Western blotting confirmed that DMMC induced the activation of mitogen-activated protein kinase (MAPK) signaling by the phosphorylation of C-Jun N-terminal kinase (JNK), resulting in the increased melanin production and the decreased phosphorylation of protein kinase B. Collectively, this study showed the pro-melanogenic effect of DMMC and its potential as a safe tanning and dyeing agent.

Serum Micronutrient Levels In Premature Canities: A Systematic Review and Meta-analysis.

Background: Premature canities, also known as premature graying of hair, is the graying of hair before 20 years old in Caucasians, before 25 years old in Asians, and before 30 years old in African–Americans. The risk factors for premature canities are multifactorial. The role of micronutrient deficiency has long been suggested to be involved in the etiopathogenesis of premature canities. The management of premature canities remains limited and far from satisfactory; hence, knowing what vitamins and minerals can help in treating premature canities is vital. Aim: This study aims to analyze serum vitamin B12, iron, ferritin, copper, calcium, and zinc levels in premature canities. Methods: The MEDLINE/PubMed electronic database, Cochrane library, ClinicalTrials.gov, EBSCO, Scopus, ProQuest, Cambridge Core, reference lists, conference proceedings, and researchers in fields of eligible studies were searched. Twelve studies (n = 1791 subjects) were included in qualitative analysis of which nine studies (n = 1381 subjects) were included in meta-analysis. Serum levels of micronutrients (vitamin B12, iron, ferritin, copper, calcium, and zinc) were compared in the premature canities and nonpremature canities groups. Result: Pooling of data using fixed-effects model found the overall effect mean difference serum vitamin B12 level was −0.697 ± 0.105 (95% CI = −0.904 to −0.490), p &lt; 0.001. The overall mean difference serum iron level was 0.146 ± 0.105 (95% CI = −0.058 to 0.350), p = 0.161. The overall mean difference serum ferritin level was 0.720 ± 0.071 (95% CI = 0.585 to 0.854), p &lt; 0.001. The overall mean difference serum copper level was 0.230 ± 0.118 (95% CI = −0.003 to 0.463, p = 0.053. The overall mean difference serum calcium level was −0.443 ± 0.114 (95% CI = −0.655 to −0.212), p &lt; 0.001. The overall mean difference serum zinc level was −0.104 ± 0.138 (95% CI = 0.377 to 0.170, p = 0.457. Qualitative analysis showed that vitamin B12 plays an important role in DNA synthesis in the proliferation of hair follicle cells and in melanogenesis. Iron, ferritin, copper, calcium, and zinc also play important roles in stabilizing and increasing tyrosinase activity in several stages of the melanogenesis process. Conclusion: The meta-analysis showed that serum levels of vitamin B12, ferritin, and calcium were significantly lower in premature canities. Although the lower serum iron, copper, and zinc levels were not significantly different in premature canities compared with nonpremature canities. Qualitative analysis found that deficiency of vitamin B12, iron, ferritin, zinc, copper, and calcium can affect the physiology of hair melanogenesis that causing premature canities.

A colorimetric fluorescent probe for the detection of tyrosinase and its application for the food industry

A colorimetric fluorescent probe for the detection of tyrosinase was developed. The quantitative range of tyrosinase activity detection was 0–10 U/mL and the LOD was 0.23 U/mL. In addition, the light yellow of the probe solution gradually turned to bright yellow with the increase of tyrosinase activity. In addition, the G and R pixel values of photos of the solutions had linear relationships with the tyrosinase activity. The probe successfully quantified the tyrosinase activity in real food samples. This research shows that this method could allow for the semi-quantitative detection of tyrosinase by smartphones, without the need for any further equipment.

Effects of Growth Hormone in Human Melanoma Drug Resistance

Melanoma, an extremely drug resistant form of cancer, displays elevated levels of growth hormone (GH) and growth hormone receptor (GHR) expression. We have described a GH dependent mechanism of chemoresistance in melanoma through a series of earlier studies. In GHR overexpressing human melanoma, GH action drives active drug efflux and phenotype switching by upregulating ATP-binding cassette transporters (ABC-transporters) and epithelial-to-mesenchymal transition (EMT) markers. Inhibition of GHR activation reverses these effects, increases drug retention, and sensitizes the melanoma cells to chemotherapy. GH action in melanoma also appears to drive drug sequestration in melanosomes as we present here. GH action was found to modulate the levels of melanocyte-inducing transcription factor (MITF), the master regulator of melanosome synthesis and melanoma. Additionally, MITF target gene levels and drug sequestering ABC transporter expression were also elevated by GH treatment in vitro and in vivo in mouse tumor xenografts. This was corroborated by in silico analyses of tumor databases. Furthermore, we observed a dose dependent increase in tyrosinase activity and melanogenesis in human melanoma cells with GH, in the presence of chemotherapy, which was suppressed by siRNA mediated GHR inhibition. Thus, we describe an array of molecular mechanisms by which GH drives chemoresistance in melanoma. Therefore, GHR inhibition combined with chemotherapy should lead to better tumor clearance and improve overall survival.

541 Inhibition of soluble adenylyl cyclase (sAC) rescues defective melanosomal pH and pigmentation in oculocutaneous albinism type 2 (OCA2)

Oculocutaneous albinism type 2 (OCA2) results from a defective melanosomal anion channel leading to an acidic melanosomal pH, reduced tyrosinase activity and decreased melanin production. Reduced melanin production in OCA2 affected people leads to the development of skin cancers and other forms of damage due to ultraviolet radiation. Currently, pharmacological approaches to repair melanosomal pH and pigmentation do not exist. We have shown that inhibition of soluble adenylyl cyclase (sAC) in melanocytes alkalinizes melanosomal pH and enhances tyrosinase (TYR) activity. Therefore, we asked whether inhibition of sAC would restore wild type melanosomal pH and melanin production in OCA2 melanocytes and mice. OCA2 melanocytes had a more acidic melanosomal pH and sAC inhibitors restored wild type melanosomal pH and increased tyrosinase activity. We generated Oca2-/-, sAC floxed (f/f), Tyr-CRE-ERT2 mice and induced sAC knock out via post-natal (P2-4), topical application of 4-hydroxytamoxifen. The Oca2-/-; sAC-/- mice (n=23) had noticeably darker hair color at P28 as compared to OCA2-/-; sACf/f (n=14) littermates. HPLC analysis of the hair collected on P28 showed a significant increase in total melanin in Oca2-/-; sAC-/- mice corresponding to increased amounts of both eumelanin (PTCA) and pheomelanin (AHP). Individual hair strands of Oca2-/-; sAC -/- mice revealed distinctive banding patterns as compared to Oca2-/-; sACf/f littermates, and histology showed that the Oca2-/-; sAC -/- mice also had less overall hair follicles. Thus, loss of sAC in melanocytes may affect hair morphogenesis. In conclusion, our studies show that restoring melanosomal pH by inhibiting the sAC signaling pathway is a potential therapeutic approach for the treatment of OCA2 and related diseases.

Effect of Irradiation with Visible Light (Green, Red, Blue) on Inhibition of Melanin Biosynthesis

Purpose: This study aims to investigate the inhibitory effect and regulatory mechanism of melanin biosynthesis in mouse-derived B16 melanoma cells (B16F10), using a light emitting diode (LED) light source irradiation device of three single wavelengths (630, 470, 525 nm) for irradiation of visible light (green, red, blue). Methods: Using three single-wavelength LED light sources, cytotoxicity, tyrosinase activity, and melanin biosynthesis were measured. Results: LED irradiation with green, red, and blue wavelengths did not show cytotoxicity or changes in melanin content at each wavelength. When the wavelength was irradiated alone, the blue and green LED wavelengths caused a decrease in tyrosinase activity, blocking the intracellular signaling mechanism that caused the increase in tyrosinase activity induced by α-melanocyte-stimulating hormone (α-MSH). In addition, protein kinase A cascade, an intracellular signaling mechanism that causes an increase in tyrosinase activity induced by α-MSH, was blocked, as it was inhibited with cyclic adenosine monophosphate (cAMP). Red series wavelength LED did not lead to any reaction. Conclusion: The irradiation of blue and green series wavelength LEDs among visible lights controls the mechanism involved in melanin formation in skin cells and results in skin whitening, which suggests that it can be effective in the whitening and cosmetic industry using LED in the future.

Increase of tyrosinase activity at the wound site in zebrafish imaged by a new fluorescent probe.

Tyrosinase plays a pivotal role in the hyperpigmentation of wounds. Here, we develop a new fluorescent probe and with it, we reveal an increase of tyrosinase activity at the wound site in zebrafish.

Melanogenesis Effect of 7-acetoxy-4-methylcoumarin in B16F10 Melanoma Cells

The increased interest in anti-whitening dyes has enhanced the research interest to identify efficient melanogenic activators. Melanogenesis is the process of melanin production by melanocytes in the hair follicles and skin, which is mediated by several enzymes, such as microphthalmia-associated transcription factor (MITF), tyrosinase (TYR), tyrosinase-related protein (TRP)-1, and TRP-2. This study investigated the melanogenesis-stimulating effect of 4-Methylumbelliferone (4MUMB) and its synthetic derivatives, 7-acetoxy-4-methylcoumarin (7A4MC) and 4-methylheriniarin (4MH) in B16F10 melanoma cells. The cytotoxicity of these compounds was investigated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay, followed by the assessment of the melanin content and the intracellular TYR activity. Finally, the expression levels of the key enzymes involved in melanogenesis were investigated. 7A4MC increased melanin production in B16F10 cells relative to that by 4MUMB and 4MH treated cells in a dose-dependent manner without significant cytotoxicity. Concomitantly, 7A4MC significantly increased TYR activity and enhanced the expression of MITF, which significantly induced the expression of TRP-1, TRP-2, and TYR. Furthermore, 7A4MC stimulated melanogenesis via increased phosphorylation of c-Jun N-terminal kinases (JNK) and reduced phosphorylation of protein kinase B (AKT). These results confirmed the melanogenesis-inducing effects of 7A4MC and indicated its potential use as an anti-hair bleaching agent in cosmetics industries.

Protoporphyrin IX Stimulates Melanogenesis, Melanocyte Dendricity, and Melanosome Transport Through the cGMP/PKG Pathway.

Protoporphyrin IX (PPIX) is a heterocyclic organic compound that is the last intermediate in the heme biosynthetic pathway. PPIX, due to its photodynamic effects, is utilized in the treatment of skin diseases. Furthermore, PPIX has been utilized as a melanogenesis-stimulating agent in various studies. However, the exact function and mechanism underlying PPIX action in melanocytes remain to be elucidated. In the present study, we sought to further investigate how PPIX affects melanocyte melanogenesis, and whether PPIX is involved in melanin transport. Our findings demonstrated that PPIX increased melanocyte dendricity and melanosome transport, in addition to increasing melanogenesis. PPIX functions primarily by activating the guanylate cyclase (GC) and cyclic guanosine 3’, 5’-monophosphate/protein kinase G (cGMP/PKG) signaling pathways. Once activated, these pathways increase tyrosinase activity and the expression of microphthalmia-associated transcription factor (MITF), tyrosinase, tyrosinase-related protein-1 and -2 (TRP-1 and TRP-2), myosin Va, melanophinin, Ras-related protein Rab-27A (Rab27a), and cell division cycle 42 (Cdc42), promoting melanogenesis, melanocyte dendricity, and melanosome transport. Furthermore, the melanogenic effects of PPIX were confirmed in vivo in a zebrafish model system. Our results indicate that PPIX is not cytotoxic and may, thus, be utilized as a pigmentation enhancer.