Eumelanin is a heteropolymer that is generally composed of hydroxylated indole residues and plays diverse protective functions in various species. Melanin is derived from the amino acid tyrosine and production of melanin is a highly complex oxidative process with a number of steps that can either proceed enzymatically or non-enzymatically. Although melanin plays important protective roles in many species, during melanization, particularly in steps that can proceed non-enzymatically, many toxic intermediates are produced, including semiquinones, dopaquinone, indole-quinones and moreover, the production of many reactive oxygen species. To mitigate the production of reactive species, a number of proteins that regulate the biochemical process of melanization have evolved in various living species, which is closely related to adaptation and physiological requirements. In this communication, we discuss differences between non-enzymatic and enzymatic processes of melanization and the enzymatic regulation of melanization in difference species with an emphasis on differences between mammals and insects. Comparison between melanization and insect sclerotization is also emphasized which raises some interesting questions about the current models of these pathways.
Animals ; Biological Evolution ; Humans ; Insecta ; metabolism ; Mammals ; metabolism ; Melanins ; biosynthesis ; chemistry ; Models, Biological ; Species Specificity

BACKGROUND: Melanin is detectable in various sense organs including the skin in animals. It has been reported that melanin adsorbs toxic elements such as mercury, cadmium, and lead. In this study, we investigated the adsorption of molybdenum, which is widely recognized as a toxic element, by melanin. METHODS: Molybdenum level of the mouse skin was measured by inductively coupled plasma mass spectrometry. The pigmentation level of murine skin was digitalized as the L* value by using a reflectance spectrophotometer. An in vitro adsorption assay was performed to confirm the interaction between molybdenum and melanin. RESULTS: Our analysis of hairless mice with different levels of skin pigmentation showed that the level of molybdenum increased with an increase in the level of skin pigmentation (L* value). Moreover, our analysis by Spearman's correlation coefficient test showed a strong correlation (r = - 0.9441, p < 0.0001) between L* value and molybdenum level. Our cell-free experiment using the Langmuir isotherm provided evidence for the adsorption of molybdenum by melanin. The maximum adsorption capacity of 1 mg of synthetic melanin for molybdenum was 131 μg in theory. CONCLUSION Our in vivo and in vitro results showed a new aspect of melanin as an adsorbent of molybdenum.
Adsorption ; Animals ; Melanins ; chemistry ; metabolism ; Mice ; Mice, Hairless ; Mice, Transgenic ; Molybdenum ; chemistry ; metabolism ; pharmacology ; Skin ; chemistry ; drug effects ; Skin Pigmentation ; drug effects ; Water Pollutants, Chemical ; chemistry ; metabolism ; pharmacology

Tea contains polyphenols and is one of the most popular beverages consumed worldwide. Because most tyrosinase inhibitors that regulate melanogenesis are phenol/catechol derivatives, this study investigated the inhibitory effects of Camellia sinensis water extracts (CSWEs), including black tea, green tea, and white tea extracts, on melanogenesis using immortalized melanocytes. CSWEs inhibited melanin accumulation and melanin synthesis along with tyrosinase activity in a concentration-dependent manner. These inhibitory effects were superior to those of arbutin, a well-known depigmenting agent. The anti-melanogenic activity of black (fermented) tea was higher than that of a predominant tea catecholamine, epigallocatechin gallate. CSWEs, especially black tea extract, decreased tyrosinase protein levels in a concentration-dependent manner. These results suggest that the anti-melanogenic effect of CSWEs is mediated by a decrease in both tyrosinase activity and protein expression, and may be augmented by fermentation. Thus, CSWEs could be useful skin-whitening agents in the cosmetic industry.
Animals ; Catechin/analogs & derivatives/metabolism ; Cell Line ; Melanins/*metabolism ; Melanocytes/enzymology/*metabolism ; Mice ; Monophenol Monooxygenase/*metabolism ; Plant Extracts/*pharmacology ; Plant Leaves/chemistry ; Tea/*chemistry

OBJECTIVETo investigate the effects of Liuwei Dihuang (LWDH) decoction on serotonine (5-HTs), melatonin and the activity of the rate-limiting enzymes ANNAT and HIOMT in cultured human melanocytes and in melanocytes co-cultured with keratinocytes.

METHODSCCK-8 assay was used to assess the proliferation of melanocytes and melanocytes co-cultured with keratinocytes after treatment with the serum from rabbits fed with LWDH decoction. High-performance liquid chromatography was used to determine 5-HT and melatonin contents, and real-time fluorescent PCR was employed to evaluate the ANNAT and HIOMT activities in the cell cultures.

RESULTSThe serum from rabbits fed with LWDH Decoction at low doses did not affect the proliferation of melanocytes co-cultured with keratinocytes, but at the concentrations of 20%-40%, the serum significantly inhibited the proliferation of melanocytes, and the effect was optimal with a concentration of 40% (P<0.05). 5-HT and melatonin contents in the cell culture decreased as the serum concentration increased (P<0.05), which was the most obvious with a serum concentration of 40% (P<0.01). Exposure of the cells to low and moderate doses of the serum caused a dose-dependent decrease in AANAT activity (P<0.05), but the serum produced no significant changes in the level of HIOMT mRNA expression in the cells.

COUCLUSIONSThe serotoninergic/melatoninergic system mediate the regulation of melanin metabolism by LWDH Decoction, the mechanism of which may involve 5-HTs, melatonin and ANNAT.

Animals ; Cells, Cultured ; Coculture Techniques ; Drugs, Chinese Herbal ; pharmacology ; Humans ; Keratinocytes ; Melanins ; metabolism ; Melanocytes ; drug effects ; metabolism ; Melatonin ; metabolism ; Rabbits ; Serotonin ; metabolism ; Serum ; chemistry

This study aimed to evaluate the biological effect and mechanism of Vernonia anthelmintica Injection(VAI) on melanin accumulation. The in vivo depigmentation model was induced by propylthiouracil(PTU) in zebrafish, and the effect of VAI on melanin accumulation was evaluated based on the in vitro B16F10 cell model. The chemical composition of VAI was identified according to the high-performance liquid chromatography quadrupole-time-of-flight tandem mass spectrometry(UPLC-Q-TOF-MS). Network pharmaco-logy was applied to predict potential targets and pathways of VAI. A "VAI component-target-pathway" network was established, and the pharmacodynamic molecules were screened out based on the topological characteristics of the network. The binding of active molecules to key targets was verified by molecular docking. The results showed that VAI promoted tyrosinase activity and melanin production in B16F10 cells in a dose-and time-dependent manner and could restore the melanin in the body of the zebrafish model. Fifty-six compounds were identified from VAI, including flavonoids(15/56), terpenoids(10/56), phenolic acids(9/56), fatty acids(9/56), steroids(6/56), and others(7/56). Network pharmacological analysis screened four potential quality markers, including apigenin, chrysoeriol, syringaresinol, and butein, involving 61 targets and 65 pathways, and molecular docking verified their binding to TYR, NFE2L2, CASP3, MAPK1, MAPK8, and MAPK14. It was found that the mRNA expression of MITF, TYR, TYRP1, and DCT in B16F10 cells was promoted. By UPLC-Q-TOF-MS and network pharmacology, this study determined the material basis of VAI against vitiligo, screened apigenin, chrysoeriol, syringaresinol, and butein as the quality markers of VAI, and verified the efficacy and internal mechanism of melanogenesis, providing a basis for quality control and further clinical research.
Animals ; Vernonia/chemistry* ; Melanins/metabolism* ; Zebrafish/metabolism* ; Network Pharmacology ; Molecular Docking Simulation ; Apigenin/pharmacology* ; Drugs, Chinese Herbal/pharmacology* ; Chromatography, High Pressure Liquid

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

In this study, the essential oil from lotus flower extract, including petals and stamens, was assessed with regard to its effects on melanogenesis in human melanocytes. The lotus flower essential oil was shown to stimulate melanin synthesis and tyrosinase activity in a dose-dependent manner. The lotus flower essential oil induced the expression of tyrosinase, microphthalmia-associated transcription factor M (MITF-M), and tyrosinase-related proten-2 (TRP-2) proteins, but not tyrosinase mRNA. Moreover, it increased the phosphorylation of ERK and cAMP response element binding protein (CREB). In order to verify the effective components of the lotus flower oil, its lipid composition was assessed. It was found to be comprised of palmitic acid methyl ester (22.66%), linoleic acid methyl ester (11.16%), palmitoleic acid methyl ester (7.55%) and linolenic acid methyl ester (5.16%). Among these components, palmitic acid methyl ester clearly induced melanogenesis as the result of increased tyrosinase expression, thereby indicating that it may play a role in the regulation of melanin content. Thus, our results indicate that lotus flower oil may prove useful in the development of gray hair prevention agents or tanning reagents.
Blotting, Western ; Cell Proliferation ; Cyclic AMP/metabolism ; Cyclic AMP Response Element-Binding Protein/genetics/metabolism ; Flowers/*chemistry ; Gas Chromatography-Mass Spectrometry ; Humans ; Intramolecular Oxidoreductases/genetics/metabolism ; Lotus/*chemistry ; Melanins/*biosynthesis ; Melanocytes/*drug effects/metabolism ; Microphthalmia-Associated Transcription Factor/genetics/metabolism ; Monophenol Monooxygenase/genetics/metabolism ; Phosphorylation ; Plant Oils/*pharmacology ; RNA, Messenger/genetics/metabolism ; Reverse Transcriptase Polymerase Chain Reaction ; Skin/cytology/drug effects/metabolism

The anti-melanogenesis effect of glyceollins was examined by melanin synthesis, tyrosinase activity assay in zebrafish embryos and in B16F10 melanoma cells. When developing zebrafish embryos were treated with glyceollins, pigmentation of the embryos, melanin synthesis and tyrosinase activity were all decreased compared with control zebrafish embryos. In situ expression of a pigment cell-specific gene, Sox10, was dramatically decreased by glyceollin treatment in the neural tubes of the trunk region of the embryos. Stem cell factor (SCF)/c-kit signaling pathways as well as expression of microphthalmia-associated transcription factor (MITF) were determined by western blot analysis. Glyceollins inhibited melanin synthesis, as well as the expression and activity of tyrosinase induced by SCF, in a dose-dependent manner in B16F10 melanoma cells. Pretreatment of B16F10 cells with glyceollins dose-dependently inhibited SCF-induced c-kit and Akt phosphorylation. Glyceollins significantly impaired the expression and activity of MITF. An additional inhibitory function of glyceollins was to effectively downregulate intracellular cyclic AMP levels stimulated by SCF in B16F10 cells. Glyceollins have a depigmentation/whitening activity in vitro and in vivo, and that this effect may be due to the inhibition of SCF-induced c-kit and tyrosinase activity through the blockade of downstream signaling pathway.
Animals ; Embryo, Nonmammalian/drug effects ; Melanins/*biosynthesis ; Melanoma, Experimental/metabolism/pathology ; Mice ; Monophenol Monooxygenase/metabolism ; Phosphorylation/drug effects ; Pigmentation/drug effects ; Proto-Oncogene Proteins c-kit/*metabolism ; Pterocarpans/chemistry/*pharmacology ; SOXE Transcription Factors/metabolism ; Sesquiterpenes/chemistry/*pharmacology ; Signal Transduction/*drug effects ; Soybeans/*chemistry ; Stem Cell Factor/*pharmacology ; Zebrafish/embryology/metabolism

Human skin color shows variations throughout life and influenced by various factors such as race, sex, age and hormones. Since the development of spectrophotometer, many studies on human skin color have been done. However, few studies have been carried out to measure the skin color of neonatal infants. The aim of our study was to assess the variations in skin color according to site, gestational age, birth weight and season of birth in Korean neonates. A total of 447 healthy neonates (3 days after birth, 213 males and 234 females) were enrolled in the present study. Skin pigmentation was measured by reflectance spectrophotometer (Derma-Spectrophotometer(R), Cortex technology, Hadsund, Denmark) at four different sites (forehead, upper arm, abdomen, and inguinal area). The forehead showed highest melanin index in all sites measured (p<0.05). There was no significant difference according to gestational age, birth weight, and season of birth. This result imply that the skin color in neonates is mainly determined genetically.
Arm/pathology ; Birth Weight ; Female ; Forehead/pathology ; Gestational Age ; Humans ; Infant, Newborn ; Korea ; Male ; Melanins/chemistry/*metabolism ; Seasons ; Sex Factors ; Skin/*pathology ; *Skin Physiology ; Skin Pigmentation ; Spectrophotometry ; Time Factors