Pueraria protein extract inhibits melanogenesis and promotes melanoma cell apoptosis through the regulation of MITF and mitochondrial­related pathways.

Pueraria Lobata Radix (P. Lobata Radix) is an edible traditional Chinese medicine that contains various active compounds. Proteins from P. Lobata Radix have become the subject of increased interest in recent years. In evaluating the whitening effect on the skin, the present study found that the P. Lobata Radix water­soluble total protein extract (PLP) had the strongest inhibitory effect on tyrosinase activity. In the present study, the anti­melanogenic effect of PLP and the inhibitory effect on B16 melanoma cells were investigated. PLP significantly reduced the tyrosinase activity and melanin content in B16 melanoma cells. Mechanistically, PLP inhibited melanogenesis by decreasing the expression of tyrosinase, tyrosinase­related protein (TRP)­1 and TRP­2 through downregulation of the microphthalmia­associated transcription factor (MITF) gene, which was mediated by inhibition of p38 mitogen­activated protein kinase signaling. In addition, PLP inhibited cell viability and triggered apoptosis of B16 cells in a dose­dependent manner. Exposure to PLP reduced the mitochondrial membrane potential (MMP) and decreased ATP generation, leading to mitochondria­related apoptosis of B16 melanoma cells. The expression levels of succinate dehydrogenase (SDH) and its two related subunits (SDHA and SDHB) were downregulated significantly by PLP, which may be associated with the regulation of mitochondrial energy metabolism by PLP. These results may explain why MMP collapse and reduced ATP generation were observed in B16 melanoma cells treated with PLP. Finally, the present study demonstrated that the inhibition of melanin synthesis by PLP was correlated with the regulation of antioxidant enzymes to reduce reactive oxygen species levels. These results suggested that PLP inhibits melanogenesis by downregulating the expression of MITF­related melanogenic enzymes and triggering apoptosis through mitochondria­related pathways.

The melanin inhibitory effect of plants and phytochemicals: A systematic review.

BACKGROUND: Melanin plays an important role in protecting human skin, while excessive synthesis of melanin can cause abnormal pigmentation and induce skin diseases. Long-term use of commercial whitening agents in managing skin melanin such as kojic acid and arbutin can lead to some negative effects such as dermatitis and liver cancer. Although past studies have researched the melanin inhibitory effect of plant extracts, the effective dose and mechanisms are not well summarized and discussed. This study aims to explore the melanin inhibitory property of phytochemicals and tries to answer the following research questions: (1) Which plant extracts and phytochemicals could inhibit melanin biosynthesis in the skin? what is the mechanism of action? (2) Have human trials been conducted to confirm their melanin inhibitory effect? (3) If not, which phytochemicals are recommended for further human trials? This article would provide information for future research to develop natural and safe skin whitening products. METHODS: A preferred reporting items for systematic reviews and meta-analyses (PRISMA) systematic review method and OHAT risk-of-bias tool were applied to screen literature from 2000 to 2021 and 50 research articles met the selection criteria. RESULTS: Flavonoids, phenolic acids, stilbenes and terpenes are main classes of phytochemicals responsible for the melanin inhibitory effects. The in vitro/in vivo melanin inhibitory effects of these plant extracts/phytochemicals are achieved via three main mechanisms: (1) the ethyl acetate extract of Oryza sativa Indica cv., and phytochemicals such as galangin and origanoside could manage melanin biosynthesis through competitive inhibition, non-competitive inhibition or mixed-type inhibition of tyrosinase; (2) phytochemicals such as ginsenoside F1, ginsenoside Rb1 and 4­hydroxy-3-methoxycinnamaldehyde could inhibit melanogenesis through down-regulating microphthalmia-related transcription factor (MITF) gene expression via different signalling pathways; (3) the ethanolic extracts of Dimorphandra gardneriana, Dimorphandra gardneriana, Lippia microphylla and Schinus terebinthifolius have a good ultraviolet absorption ability and high sun protective factor (SPF) values, thereby inhibiting UV induced melanogenesis in the skin. CONCLUSION: Although many plant extracts and phytochemicals have been found to inhibit melanin production, most of the results were only proved in cellular and/or animal models. Only the ethyl acetate extract of Oryza sativa Indica cv. panicle, and ginsenoside F1 were proved effective in human trials. Animal studies proved the effectiveness of galangin, origanoside, ginsenoside Rb1 and 4­hydroxy-3-methoxycinnamaldehyde with effective dose below 3 mM, and therefore recommended for future human trial. In addition, cellular studies have demonstrated the effectiveness of oxyresveratrol, mulberroside A, kurarinol, kuraridinol, plumbagin, (6aR,11aR)-3,8-dihydroxy-9­methoxy pterocarpan, ginsenoside Rh4, cardamonin, nobiletin, curcumin, ß-mangostin and emodin in inhibiting melanin synthesis at low concentrations of 20 µM and proved the low SPF values of Dimorphandra gardneriana, Dimorphandra gardneriana, Lippia microphylla and Schinus terebinthifolius extracts, and therefore recommended for further animal and human trials.

Ferroptosis and Apoptosis Are Involved in the Formation of L-Selenomethionine-Induced Ocular Defects in Zebrafish Embryos.

Selenium is an essential trace element for humans and other vertebrates, playing an important role in antioxidant defense, neurobiology and reproduction. However, the toxicity of excessive selenium has not been thoroughly evaluated, especially for the visual system of vertebrates. In this study, fertilized zebrafish embryos were treated with 0.5 µM L-selenomethionine to investigate how excessive selenium alters zebrafish eye development. Selenium-stressed zebrafish embryos showed microphthalmia and altered expression of genes required for retinal neurogenesis. Moreover, ectopic proliferation, disrupted mitochondrial morphology, elevated ROS-induced oxidative stress, apoptosis and ferroptosis were observed in selenium-stressed embryos. Two antioxidants-reduced glutathione (GSH) and N-acetylcysteine (NAC)-and the ferroptosis inhibitor ferrostatin (Fer-1) were unable to rescue selenium-induced eye defects, but the ferroptosis and apoptosis activator cisplatin (CDDP) was able to improve microphthalmia and the expression of retina-specific genes in selenium-stressed embryos. In summary, our results reveal that ferroptosis and apoptosis might play a key role in selenium-induced defects of embryonic eye development. The findings not only provide new insights into selenium-induced cellular damage and death, but also important implications for studying the association between excessive selenium and ocular diseases in the future.

Inhibitory effects and underlying mechanisms of Artemisia capillaris essential oil on melanogenesis in the B16F10 cell line.

The present study investigated the anti­melanogenic activity of 10 essential oils using the B16F10 cell model. Initially, a wide range of concentrations of these essential oils were screened in order to determine their toxicity levels. The assigned non­toxic concentrations of the tested essential oils were then used to evaluate their effects on melanogenesis. The effects of the essential oils with potent anti­melanogenic activity on cell proliferation, protection against H2O2­induced cell death and the expression of certain melanogenesis­related genes, including MITF, tyrosinase, tyrosinase related protein (TRP)­1 and TRP­2 were also evaluated. The results revealed that the essential oils extracted from Citrus unshiu, Juniperus chinensis L., Zanthoxylum piperitum and Artemisia capillaris (A. capillaris) inhibited melanogenesis. However, among these four extracts, only A. capillaris extract enhanced cell proliferation, exhibited anti­H2O2 activities and decreased the expression level of TRP­1. It was demonstrated that A. capillaris extract inhibited melanin synthesis via the downregulation of the TRP­1 translational level. These essential oil extracts, particularly that of A. capillaris, may thus be used as natural anti­melanogenic agents for therapeutic purposes and in the cosmetic industry for skin whitening effects with beneficial proliferative properties. However, further studies using in vivo models are required to validate these findings and to examine the effects of these extracts on various molecular pathways.

The Incoherent Fluctuation of Folate Pools and Differential Regulation of Folate Enzymes Prioritize Nucleotide Supply in the Zebrafish Model Displaying Folate Deficiency-Induced Microphthalmia and Visual Defects.

OBJECTIVE: Congenital eye diseases are multi-factorial and usually cannot be cured. Therefore, proper preventive strategy and understanding the pathomechanism underlying these diseases become important. Deficiency in folate, a water-soluble vitamin B, has been associated with microphthalmia, a congenital eye disease characterized by abnormally small and malformed eyes. However, the causal-link and the underlying mechanism between folate and microphthalmia remain incompletely understood. METHODS: We examined the eye size, optomotor response, intracellular folate distribution, and the expression of folate-requiring enzymes in zebrafish larvae displaying folate deficiency (FD) and ocular defects. RESULTS: FD caused microphthalmia and impeded visual ability in zebrafish larvae, which were rescued by folate and dNTP supplementation. Cell cycle analysis revealed cell accumulation at S-phase and sub-G1 phase. Decreased cell proliferation and increased apoptosis were found in FD larvae during embryogenesis in a developmental timing-specific manner. Lowered methylenetetrahydrofolate reductase (mthfr) expression and up-regulated methylenetetrahydrofolate dehydrogenase (NADP+-dependent)-1-like (mthfd1L) expression were found in FD larvae. Knocking-down mthfd1L expression worsened FD-induced ocular anomalies; whereas increasing mthfd1L expression provided a protective effect. 5-CH3-THF is the most sensitive folate pool, whose levels were the most significantly reduced in response to FD; whereas 10-CHO-THF levels were less affected. 5-CHO-THF is the most effective folate adduct for rescuing FD-induced microphthalmia and defective visual ability. CONCLUSION: FD impeded nucleotides formation, impaired cell proliferation and differentiation, caused apoptosis and interfered active vitamin A production, contributing to ocular defects. The developmental timing-specific and incoherent fluctuation among folate adducts and increased expression of mthfd1L in response to FD reflect the context-dependent regulation of folate-mediated one-carbon metabolism, endowing the larvae to prioritize the essential biochemical pathways for supporting the continuous growth in response to folate depletion.

Antioxidant Compounds, Kirenol and Methyl ent-16α, 17-dihydroxy-kauran-19-oate Bioactivity-Guided Isolated from Siegesbeckia glabrescens Attenuates MITF-Mediated Melanogenesis via Inhibition of Intracellular ROS Production.

Siegesbeckia glabrescens (Compositae), an annual herb indigenous to Korean mountainous regions and has been eaten as a food in Korea. This study investigated ABTS, DPPH and nitric oxide (NO) radical-scavenging activities, and melanin production and TYR inhibitory effects-guided fractionation to identify therapeutic phytochemicals from S. glabrescens that can attenuate oxidation and melanogenesis in murine melanoma B16F10 cells. Nine compounds with inhibitory effects on melanin production, and TYR activity, and ABTS, DPPH, and NO radical scavenging activity were isolated from the 100% ethanol fraction from S. glabrescens. Among the nine compounds, kirenol (K), methyl ent-16α, 17-dihydroxy-kauran-19-oate (MDK) had strong inhibitory effects on melanin production and TYR activity with antioxidant effects. Western blot analysis revealed that K and MDK suppressed tyrosinase-related protein (TYRP)-1, TYRP-2 and microphthalmia-associated transcription factor (MITF) expression. Moreover, these two compounds inhibited intracellular reactive oxygen species (ROS) level in tert-butyl hydroperoxide (t-BHP)-treated B16F10 cells. Our results suggest that S. glabrescens containing active compounds such as K and MDK, which has antioxidant and antimelanogenesis effects, is the potent therapeutic and functional material for the prevention of oxidation-induced hyperpigmentation.

A prepared platelet-rich plasma extract, namely Self-Growth Colony, inhibits melanogenesis by down-regulating microphthalmia-associated transcription factor in skin melanocyte.

BACKGROUND: During melanogenesis, melanocytes produce melanin through enzymatic reactions. Microphthalmia-associated transcription factor (MITF) is a major regulator in controlling the expressions of melanogenic enzymes tyrosinase (TYR), tyrosine-related protein-1 (TRP1), and dopachrome tautomerase (DCT). Self-Growth Colony (SGC) is prepared from human platelet-rich plasma (PRP) having an enrichment of growth factors, and which has claimed skin regeneration function. AIM: In this study, we aim to identify and investigate the novel role of SGC in skin melanogenesis. METHODS: MTT assay was performed to determine the cytotoxicity of applied SGC. Melanin assay was adopted to quantify the intracellular melanin after SGC treatment. Promoter-driven luciferase assay, real-time PCR, and Western blotting were performed to determine the expressions of melanogenic enzymes and MITF in SGC-treated cultured Melan-A cells, being treated with or without UV induction. Ex vivo mouse skin was treated with SGC, and then was subjected to Western blotting and histochemical staining. RESULTS: We identified that SGC inhibited melanogenesis in cultured melanocytes and ex vivo mouse skin. The phenomena were attributed to a reduction of MITF expression, which subsequently down-regulated the melanogenic enzymes, that is, TYR, TRP1, and DCT. Moreover, ERK signaling was activated in the SGC-inhibited melanogenesis. CONCLUSIONS: The findings suggest that SGC extracting from human blood can be a safe and potential agent in promoting skin whitening.

Linear Skin Defects with Multiple Congenital Anomalies (LSDMCA): An Unconventional Mitochondrial Disorder.

Mitochondrial disorders, although heterogeneous, are traditionally described as conditions characterized by encephalomyopathy, hypotonia, and progressive postnatal organ failure. Here, we provide a systematic review of Linear Skin Defects with Multiple Congenital Anomalies (LSDMCA), a rare, unconventional mitochondrial disorder which presents as a developmental disease; its main clinical features include microphthalmia with different degrees of severity, linear skin lesions, and central nervous system malformations. The molecular basis of this disorder has been elusive for several years. Mutations were eventually identified in three X-linked genes, i.e., HCCS, COX7B, and NDUFB11, which are all endowed with defined roles in the mitochondrial respiratory chain. A peculiar feature of this condition is its inheritance pattern: X-linked dominant male-lethal. Only female or XX male individuals can be observed, implying that nullisomy for these genes is incompatible with normal embryonic development in mammals. All three genes undergo X-inactivation that, according to our hypothesis, may contribute to the extreme variable expressivity observed in this condition. We propose that mitochondrial dysfunction should be considered as an underlying cause in developmental disorders. Moreover, LSDMCA should be taken into consideration by clinicians when dealing with patients with microphthalmia with or without associated skin phenotypes.

A feasibility study of circulating melanoma cells in the perioperative context of hyperthermic isolated limb perfusion (HILP) in 20 patients.

INTRODUCTION: Hyperthermic Ιsolated Limb Perfusion using melphalan and TNFα (TM-HILP) is a regional chemotherapy method for advanced melanoma. PURPOSE: To explore the feasibility of the study of Circulating Melanoma Cells (CMCs) in the context of acute physiological changes induced by TM-HILP and their association with oncological outcomes. METHODS: The study included 20 patients undergoing TM-HILP for unresectable in-transit melanoma of the limbs, stage III(B/C/D). CMCs in the peripheral blood were analyzed at 5-time points from the preoperative day until day 7 from surgery using the following biomarkers: MITF, Tyrosinase mRNA, Melan-A and S100b, through quantitative RT-PCR. RESULTS: No CMCs according to Tyrosinase and Melan-A biomarkers were found in any sample. Friedman test showed significant alterations perioperatively for MITF (p < .001) and S100b (p = .001). Pairwise tests showed a significant increase of MITF levels on postoperative day 7 compared with postoperative day 1, intraoperative and preoperative levels (p < .05). Pairwise tests for S100b showed a significant difference between intraoperative sample and postoperative day 7 (p < .0001). Patients who experienced a complete response to TM-HILP (n = 12) had higher mean levels of MITF and the difference was significant at the time point immediately after the operation (0.29 ± 0.27 vs. 0.06 ± 0.06, p = .014) and on postoperative day 1 (1.48 ± 2.24 vs. 0.41 ± 0.65, p = .046). There was no association of MITF or S100b levels with 4-year disease specific survival. CONCLUSION: TM-HILP is associated with increased levels of CMCs, but there was no association of this increase with survival. Patients with complete response to HILP demonstrate higher values of MITF shortly after the operation.

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.

A chemical compound from fruit extract of Juglans mandshurica inhibits melanogenesis through p-ERK-associated MITF degradation.

BACKGROUND: Trials for regulation of abnormal hyperpigmentation from the use of natural products have been going on for years. Leaf and root extracts from Juglans mandshurica are reported to function as antioxidants and to suppress allergic dermatitis. However, studies evaluating its fruit extract and the chemical compounds from the fruit extract are lacking in dermatology fields, including melanogenesis. PURPOSE: The aim of this study is to understand the effect of the fruit extract from J. mandshurica on pigmentation and to search for specific chemical compounds that affect melanogenesis. METHODS: After screening out any anti-melanotic effects of the fruit extract from J. mandshurica in B16F10 melanoma cells, three major phenolic compounds isolated from the fruit extract were tested by western blot analysis for expression of microphthalmia-associated transcription factor (MITF) and tyrosinase. Their effect on B16F10 melanoma cells with regard to melanogenesis was also confirmed in primary human epidermal melanocytes (PHEMs). PD98059 was tested to observe the compounds' signaling role in the extracellular signal-regulated protein kinase (ERK)-pathway. RESULTS: Fruit extract from J. mandshurica showed anti-melanotic effects in B16F10 melanoma cells. After chemical compounds were isolated from the fruit extracts, three phenolic compounds were evaluated for anti-melanotic effects. 2-[4-(3-hydroxypropyl)-2-methoxyphenoxy]-1,3-propanediol (compound 1) showed the highest suppression effect among the three compounds. In B16F10 melanoma cells and PHEMs, reduced melanin contents were observed after treatment with the compound (1). Experiments using a blocker of ERK showed that the inhibitory effect of the compound (1) on melanogenesis was dependent on ERK-associated MITF degradation. CONCLUSION: A chemical constituent of Juglans mandshurica Maxim. induces an inhibitory mechanism to melanogenesis. It has the potential to become a whitening agent in the medical field, though this requires further clinical investigation.

Anti-melanogenic and anti-oxidant activities of ethanol extract of Kummerowia striata: Kummerowia striata regulate anti-melanogenic activity through down-regulation of TRP-1, TRP-2 and MITF expression.

Kummerowia striata (K. striata) is used as a traditional medicine for inflammation-related therapy. To determine whether it has beneficial anti-melanogenic and anti-oxidant activities, we investigated the biological activities of the ethanol extract of Kummerowia striata (EKS) using a variety of in vitro and cell culture model systems. The anti-melanogenic activity was assessed in B16F10 melanoma cells in terms of melanin synthesis and in vitro tyrosinase inhibitory activity. The anti-oxidant assays were performed using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS). EKS showed strong anti-oxidant activities in DPPH and ABTS assays. The mRNA transcription levels and protein expression levels of tyrosinase, tyrosinase-related protein 1, tyrosinase-related protein 2, and microphthalmia-associated transcription factor decreased in a dose-dependent manner with EKS treatment. Additionally, EKS did not affect cell viability at different concentrations used in this study, indicating that the mechanism of action of EKS-mediated inhibition of melanin synthesis does not involve cytotoxicity. Also, we confirmed that p-coumaric acid and quercetin are important compounds for anti-melanogenesis and antioxidant properties of EKS. Collectively, our findings demonstrate for the first time that EKS possesses anti-melanogenic and anti-oxidant activities. Further evaluation and development of EKS as a functional supplement or cosmetic may be useful for skin whitening and reducing wrinkles.

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.

Evaluation of Antioxidant and Anti-Melanogenic Activity of Different Extracts of Aerial Parts of N. Sintenisii in Murine Melanoma B16F10 Cells.

Nepeta (Lamiaceae) is an important genus with beneficial medicinal properties. N. sintenisii Bornm. has been used in folk medicine of Iran to cure various diseases. We investigated the anti-melanogenesis effects of n-hexane, MeOH, CH2Cl2, n-BuOH, EtOAc, and H2O extracts isolated from the plant in B16 melanoma cells. Various assays including cytotoxicity, mushroom tyrosinase inhibition, inhibition of cellular tyrosinase, melanin content, the amount of reactive oxygen species and western blotting were done to assess the plant activities on melanogenesis inhibition. All extracts of N. sintenisii could significantly reduce both tyrosinase activity and the cellular melanin content. Reactive oxygen species were also significantly decreased following the treatment of cell with n-BuOH and EtOAc extracts with no cytotoxicity. The plant significantly decreased the amount of microphthalmia-associated transcription factor proteins. Collectively, N. sintenisii inhibited melanin synthesis and tyrosinase activity in B16 melanoma cells with no cytotoxic effects. Hence, it might merit further investigations for elucidation of anti-hyperpigmentation agents.

Nutrient intake in women before conception and risks of anophthalmia and microphthalmia in their offspring.

BACKGROUND: We previously explored associations between nutrients including folate and other macro and micronutrients and risks of anophthalmia or microphthalmia in the National Birth Defects Prevention Study. In the current study, we expand those previous results with larger sample sizes and conduct analyses with an additional diet quality index using more recent data. METHODS: The National Birth Defects Prevention Study is a population-based, multicenter case-control study of over 30 major birth defects, with estimated due dates from October 1997 to December 2011. Cases were 224 infants diagnosed with anophthalmia or microphthalmia. Controls were 11,109 live-born, nonmalformed infants randomly selected by each study center. Mothers completed a standardized, computer-assisted telephone interview between 6 weeks and 24 months after delivery. Mothers responded to a shortened food frequency questionnaire, assessing their nutrient intake for the year before pregnancy, and questions about periconceptional (2 months before to 2 months after conception) vitamin supplement use. Nutrient intake quartiles were based on the intake among controls. RESULTS: Among vitamin supplement users, odds of anophthalmia/microphthalmia were decreased for women with intake levels in the highest quartile of folate (0.56, 95% confidence interval [CI] 0.32-0.98), magnesium (0.42, 95% CI 0.22-0.82), and vitamin E (0.50, 95% CI 0.29-0.89). Among women not reporting vitamin supplement use, the odds were significantly increased for beta-carotene (2.5, 95% CI 1.10-5.68) and decreased for retinol (0.37, 95% CI 0.19-0.73). CONCLUSIONS: In this expanded analysis, we observed associations for a few nutrients, specifically forms of vitamin A. However, the heterogeneity of results by form and vitamin use necessitates further inquiry.

Antimelanogenic Effect of an Oroxylum indicum Seed Extract by Suppression of MITF Expression through Activation of MAPK Signaling Protein.

In this study, the antimelanogenic effect of an ethyl acetate fraction of Oroxylum indicum Vent. seeds (OISEA) and its underlying mechanisms in melan-a cells were investigated. Antimelanogenesis activity was confirmed by assessing inhibition of tyrosinase activity and melanin content in the cells. Both transcriptional and translational expression of microphthalmia-associated transcription factor (MITF), tyrosinase, and tyrosinase related protein-1 and 2 (TYRP-1 and TYRP-2), were also examined. The results depicted that pretreatment of OISEA significantly inhibits not only tyrosinase activity, but melanin production and intracellular tyrosinase activity. By repressing the expression of tyrosinase, TYRP-1, TYRP-2, and MITF, OISEA interrupted melanin production. Additionally, OISEA interfered with the phosphorylation of p38, extracellular signal-regulated kinase 1/2 (ERK1/2), and c-Jun N-terminal kinase (JNK), with the reversal of OISEA-induced melanogenesis inhibition after treatment with the specific inhibitors SB239063, U0126, and SP600125. Overall, these results suggest that OISEA can stimulate p38, ERK1/2, JNK phosphorylation, and subsequent suppression of melanin, leading to the inhibition of melanogenic enzymes and melanin production, possibly owing to the presence of polyphenolic compounds.

Sageretia thea fruit extracts rich in methyl linoleate and methyl linolenate downregulate melanogenesis via the Akt/GSK3ß signaling pathway.

BACKGROUND/OBJECTIVES: Sageretia thea is traditionally used as a medicinal herb to treat various diseases, including skin disorders, in China and Korea. This study evaluated the inhibitory effect of Sageretia thea fruit on melanogenesis and its underlying mechanisms in B16F10 mouse melanoma cells. The active chemical compounds in anti-melanogenesis were determined in Sageretia thea. MATERIALS/METHODS: Solvent fractions from the crude extract were investigated for anti-melanogenic activities. These activities and the mechanism of anti-melanogenesis in B16F10 cells were examined by determining melanin content and tyrosinase activity, and by performing western blotting. RESULTS: The n-hexane fraction of Sageretia thea fruit (HFSF) exhibited significant anti-melanogenic activity among the various solvent fractions without reducing viability of B16F10 cells. The HFSF suppressed the expression of tyrosinase and tyrosinase-related protein 1 (TRP1). The reduction of microphthalmia-associated transcription factor (MITF) expression by the HFSF was mediated by the Akt/glycogen synthase kinase 3 beta (GSK3ß) signaling pathway, which promotes the reduction of ß-catenin. Treatment with the GSK3ß inhibitor 6-bromoindirubin-3'-oxime (BIO) restored HFSF-induced inhibition of MITF expression. The HFSF bioactive constituents responsible for anti-melanogenic activity were identified by bioassay-guided fractionation and gas chromatography-mass spectrometry analysis as methyl linoleate and methyl linolenate. CONCLUSIONS: These results indicate that HFSF and its constituents, methyl linoleate and methyl linolenate, could be used as whitening agents in cosmetics and have potential for treating hyperpigmentation disorders in the clinic.

Sageretia thea fruit extracts rich in methyl linoleate and methyl linolenate downregulate melanogenesis via the Akt/GSK3β signaling pathway

BACKGROUND/OBJECTIVES: Sageretia thea is traditionally used as a medicinal herb to treat various diseases, including skin disorders, in China and Korea. This study evaluated the inhibitory effect of Sageretia thea fruit on melanogenesis and its underlying mechanisms in B16F10 mouse melanoma cells. The active chemical compounds in anti-melanogenesis were determined in Sageretia thea. MATERIALS/METHODS: Solvent fractions from the crude extract were investigated for anti-melanogenic activities. These activities and the mechanism of anti-melanogenesis in B16F10 cells were examined by determining melanin content and tyrosinase activity, and by performing western blotting. RESULTS: The n-hexane fraction of Sageretia thea fruit (HFSF) exhibited significant anti-melanogenic activity among the various solvent fractions without reducing viability of B16F10 cells. The HFSF suppressed the expression of tyrosinase and tyrosinase-related protein 1 (TRP1). The reduction of microphthalmia-associated transcription factor (MITF) expression by the HFSF was mediated by the Akt/glycogen synthase kinase 3 beta (GSK3β) signaling pathway, which promotes the reduction of β-catenin. Treatment with the GSK3β inhibitor 6-bromoindirubin-3'-oxime (BIO) restored HFSF-induced inhibition of MITF expression. The HFSF bioactive constituents responsible for anti-melanogenic activity were identified by bioassay-guided fractionation and gas chromatography-mass spectrometry analysis as methyl linoleate and methyl linolenate. CONCLUSIONS: These results indicate that HFSF and its constituents, methyl linoleate and methyl linolenate, could be used as whitening agents in cosmetics and have potential for treating hyperpigmentation disorders in the clinic.

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.

N-(4-methoxyphenyl) caffeamide-induced melanogenesis inhibition mechanisms.

BACKGROUND: The derivative of caffeamide exhibits antioxidant and antityrosinase activity. The activity and mechanism of N-(4-methoxyphenyl) caffeamide (K36E) on melanogenesis was investigated. METHODS: B16F0 cells were treated with various concentrations of K36E; the melanin contents and related signal transduction were studied. Western blotting assay was applied to determine the protein expression, and spectrophotometry was performed to identify the tyrosinase activity and melanin content. RESULTS: Our results indicated that K36E reduced α-melanocyte-stimulating hormone (α-MSH)-induced melanin content and tyrosinase activity in B16F0 cells. In addition, K36E inhibited the expression of phospho-cyclic adenosine monophosphate (cAMP)-response element-binding protein, microphthalmia-associated transcription factor (MITF), tyrosinase, and tyrosinase-related protein-1 (TRP-1). K36E activated the phosphorylation of protein kinase B (AKT) and glycogen synthase kinase 3 beta (GSK3ß), leading to the inhibition of MITF transcription activity. K36E attenuated α-MSH induced cAMP pathways, contributing to hypopigmentation. CONCLUSIONS: K36E regulated melanin synthesis through reducing the expression of downstream proteins including p-CREB, p-AKT, p-GSK3ß, tyrosinase, and TRP-1, and activated the transcription factor, MITF. K36E may have the potential to be developed as a skin whitening agent.