Human Hair Melanin Research Articles

Visible Light TiO2 Photocatalyst Composite Based on Carbon Microfiber Derived from Human Hair

AbstractThe present work reports titanium dioxide (TiO2) photocatalyst composite based on human hair that can operate efficiently under visible light. The human hair melanin structure contains active sites, which can be described as a carbon compound derived from a Quinone where one of two oxygen atoms is bonded to a hydrogen radical and that can be reversibly photogenerated under visible or ultraviolet irradiation. The human hair‐derived microfibers (HHDMs) were created by the pyrolyzing hair at 850 °C, resulting in a rod‐like hollow structure. TiO2 was immobilized on the pyrolyzed hair by a simple self‐template method. The resulting composite was calcined at five different temperatures (150 to 350 °C). The HHDM and HHDM‐TiO2 morphologies and the chemical compositions were characterized using scanning electron microscopy (SEM), Energy‐dispersive X‐ray spectroscopy (EDX), X‐ray photoelectron spectroscopy (XPS), Fourier‐transform infrared spectroscopy (FTIR), and X‐ray powder diffraction (XRD). The HHDM‐TiO2 photocatalytic efficiency in degrading methylene blue was investigated and compared to that of a conventional TiO2 catalyst (P25). HHDM‐TiO2 was more effective for methylene blue degradation under visible light than the conventional P25 catalyst suspension due to the unique photosensitivity and porous structure of the composite. The catalyst calcined at 300 °C showed the best performance, which was 71% higher than that of the P25 catalyst.

Compositional changes of human hair melanin resulting from bleach treatment investigated by nanoscale secondary ion mass spectrometry

It is important to understand the influence of bleach treatment on human hair because it is one of the most important chemical treatments in hair cosmetic processes. A comparison of the elemental composition of melanin between virgin hair and bleached hair would provide important information about the structural changes of melanin. To investigate the elemental composition of melanin granules in virgin black hair and bleached hair, these hair cross-sections are analyzed by using a nanoscale secondary ion mass spectrometry (NanoSIMS). The virgin black hair and bleached hair samples were embedded in resin and smooth hair cross-sections were obtained using an ultramicrotome. NanoSIMS measurements were performed using a Cs(+) primary ion beam to detect negative secondary ions. More intensive (16) O(-) ions were detected from the melanin granules of bleached hair than from those of virgin black hair in NanoSIMS (16) O(-) ion image. In addition, it was indicated that (16) O(-) ion intensity and (16) O(-) /(12) C(14) N(-) ion intensity ratio of melanin granules in bleached hair were higher than those in virgin black hair. Nanoscale secondary ion mass spectrometry analysis of the cross-sections of virgin black hair and bleached hair indicated that the oxygen content in melanin granules was increased by bleach treatment.

Usefulness of alkaline hydrogen peroxide oxidation to analyze eumelanin and pheomelanin in various tissue samples: application to chemical analysis of human hair melanins

Eumelanin and pheomelanin in tissue samples can be specifically measured as the markers pyrrole-2,3,5-tricarboxylic acid (PTCA) and 4-amino-3-hydroxyphenylalanine after acidic permanganate oxidation and hydroiodic acid hydrolysis, respectively. Those degradation methods, although widely applied, are not easily performed in most laboratories. To overcome this difficulty, we developed alkaline H(2)O(2) oxidation in 1 M K(2)CO(3) that produces, in addition to the eumelanin marker PTCA, thiazole-2,4,5-tricarboxylic acid (TTCA) and thiazole-4,5-dicarboxylic acid (TDCA) as markers for pheomelanin and pyrrole-2,3-dicarboxylic acid (PDCA) as a marker for 5,6-dihydroxyindole-derived eumelanin. Those four degradation products can be easily separated by HPLC and analyzed with ultraviolet detection. The alkaline H(2)O(2) oxidation method is simple, reproducible and applicable to all pigmented tissues. Its application to characterize eumelanin and pheomelanin in human hair shows that PTCA and TTCA serve as specific markers for eumelanin and pheomelanin, respectively, although some caution is needed regarding the artificial production of TTCA from eumelanic tissue proteins.

Human hair melanins: what we have learned and have not learned from mouse coat color pigmentation

Hair pigmentation is one of the most conspicuous phenotypes in humans. Melanocytes produce two distinct types of melanin pigment: brown to black, indolic eumelanin and yellow to reddish brown, sulfur-containing pheomelanin. Biochemically, the precursor tyrosine and the key enzyme tyrosinase and the tyrosinase-related proteins are involved in eumelanogenesis, while only the additional presence of cysteine is necessary for pheomelanogenesis. Other important proteins involved in melanogenesis include P protein, MATP protein, α-MSH, agouti signaling protein (ASIP), MC1R (the receptor for MSH and ASIP), and SLC7A11, a cystine transporter. Many studies have examined the effects of loss-of-function mutations of those proteins on mouse coat color pigmentation. In contrast, much less is known regarding the effects of mutations of the corresponding proteins on human hair pigmentation except for MC1R polymorphisms that lead to pheomelanogenesis. This perspective will discuss what we have/have not learned from mouse coat color pigmentation, with special emphasis on the significant roles of pH and the level of cysteine in melanosomes in controlling melanogenesis. Based on these data, a hypothesis is proposed to explain the diversity of human hair pigmentation.

Human hair melanins: what we have learned and have not learned from mouse coat color pigmentation

Hair pigmentation is one of the most conspicuous phenotypes in humans. Melanocytes produce two distinct types of melanin pigment: brown to black, indolic eumelanin and yellow to reddish brown, sulfur-containing pheomelanin. Biochemically, the precursor tyrosine and the key enzyme tyrosinase and the tyrosinase-related proteins are involved in eumelanogenesis, while only the additional presence of cysteine is necessary for pheomelanogenesis. Other important proteins involved in melanogenesis include P protein, MATP protein, α-MSH, agouti signaling protein (ASIP), MC1R (the receptor for MSH and ASIP), and SLC7A11, a cystine transporter. Many studies have examined the effects of loss-of-function mutations of those proteins on mouse coat color pigmentation. In contrast, much less is known regarding the effects of mutations of the corresponding proteins on human hair pigmentation except for MC1R polymorphisms that lead to pheomelanogenesis. This perspective will discuss what we have/have not learned from mouse coat color pigmentation, with special emphasis on the significant roles of pH and the level of cysteine in melanosomes in controlling melanogenesis. Based on these data, a hypothesis is proposed to explain the diversity of human hair pigmentation.

Purification, Characterization, and Gene Cloning ofCeriporiopsissp. Strain MD-1 Peroxidases That Decolorize Human Hair Melanin

Ceriporiopsis sp. strain MD-1, isolated from forest soil, produced several extracellular enzymes that decolorized human hair melanin. Among them, three enzymes (E1, E2-1, and E2-2) were purified to homogeneity and characterized. The enzymes required hydrogen peroxide in their enzyme reactions and, typical of other fungal peroxidases, oxidized various phenol compounds such as guaiacol, but not 3,4-dimethoxybenzyl alcohol. The spectra of the three enzymes showed an absorption maximum at 406 nm, indicating that they were heme proteins. However, the A(406)/A(280) values of the enzymes were below 0.4, which was lower than those of other peroxidases. E2-1 and E2-2 were similar to each other in their molecular and catalytic properties, and they possibly represent products of posttranslational modifications and/or allelic variants of the same gene, mdcA. The corresponding cDNA was cloned and sequenced; the deduced amino acid sequence showed high identities to the manganese peroxidases from other microorganisms. The specific activities and K(m) values of E2-1 and E2-2 for synthetic and human hair melanins were much higher than those of Phanerochaete chrysosporium manganese peroxidase and lignin peroxidase.

Characterization of human hair melanin and its degradation products by means of magnetic resonance techniques

Melanin granules (MGs) have been extracted from human Chinese black hairs by either acid hydrolysis (CH-type MGs) or enzymatic digestion (CP-type MGs), and their chemical structure investigated at the solid state by means of (13)C cross polarization magic angle spinning (CPMAS NMR) and EPR spectroscopy. Both types of MGs contain a large amount of protein that is tightly bound to the true melanin polymer, with CP-type MGs having a larger protein content than CH-type ones. Moreover, MGs may also contain variable amounts of lipid-like material. A high amount of paramagnetic metals is detected by EPR in CP-type MGs, in particular Fe(III). Iron can be bound in two chemical forms: as isolated high spin Fe(III) ions with rhombic symmetry and as small oxy-hydroxy Fe(III) aggregates. Iron is poorly available to chelators. CH-type MGs contain much fewer metals. CP-type MGs have then been subjected to partial bleaching by hydrogen peroxide in ammonia, yielding a residual solid, called residual oxidized melanin (ROM) and a soluble but still pigmented fraction called melanin free acid (MFA). MFA can be isolated by precipitation at acidic pH. The (13)C-CPMAS NMR and EPR spectra of these derivatives indicated that ROM has a structure very similar to that of parent MGs, whereas MFA shows a decrease of the protein content with respect to the melanin and a decreased amount of bound iron. Thus, the oxidative degradation of CP-type MGs is a process not involving the bulk of MGs, but rather it proceeds from the solvent-exposed outer parts to the interior.

Solid‐state cross‐polarization magic angle spinning 13C and 15N NMR characterization of Sepia melanin, Sepia melanin free acid and Human hair melanin in comparison with several model compounds

AbstractThis paper presents the high‐resolution 13C and 15N cross‐polarization magic angle spinning (CP/MAS) NMR spectra of three natural melanin solids: Sepia officinalis melanin, Sepia officinalis melanin free acid (MFA) and Human hair melanin. The functional group characterization of Human hair melanin by NMR is the first to date and the 13C CP/MAS NMR spectra reported here show improved resolution of chemically inequivalent sites. The observed spectral regions of the solid melanin samples can be assigned to the postulated structural unit of the polymer chain of Sepia MFA derived from solution‐state NMR studies. To assist in the assignment of functional groups in the spectra, the solid‐state CP/MAS NMR spectra are compared with high‐resolution 13C and 15N CP/MAS spectra of four model compounds, L‐dopa, dopamine, 2‐methoxycarbonyl‐3‐ethoxycarbonyl‐4‐methylpyrrole and ethyl 5,6‐dimethoxyindole‐2‐carboxylate. To aid further in the assignment of protonated and non‐protonated carbon atoms, CP contact time dependence and non‐quaternary carbon suppression (NQS) experiments were performed on the melanin samples. The 15N CP/MAS spectra of the melanin samples confirm the presence of indole and pyrrole units in the melanin polymer chain. The NMR peaks observed in all of the melanin samples are relatively broad, presumably owing to the presence of free radicals. Electron spin resonance (ESR) data shows that all three melanin samples contain localized free radicals (g = 2.007), with the Sepia melanin containing a 10‐fold higher free radical density than Human hair melanin. Copyright © 2003 John Wiley & Sons, Ltd.

1H NMR spectroscopic characterization of solutions of Sepia melanin, Sepia melanin free acid and human hair melanin.

A 1H nuclear magnetic resonance study of Sepia melanin, Sepia melanin free acid (Sepia MFA) and human hair melanin was carried out in deuterium oxide solution at pH 10-11. The empirical formula of Sepia MFA was calculated and used to estimate the number of protons in the aromatic region of the Sepia MFA polymeric chain and to suggest a possible monomeric unit profile.

On the structure of human hair melanins from an infrared spectroscopy analysis of their interactions with Cu 2+ ions

Melanins were isolated from dark and red human hair and complexed with copper ions at various pH values in a complexing medium. IR spectra of melanins and their Cu 2+-complexes for pellets with KBr were obtained. The IR spectra indicate that Cu 2+ ions bound to melanins are fixed by different carboxyl and hydroxyl (phenolic and/or alcoholic) groups in the macromolecule. From these results it is concluded that, generally, melanin carboxyl groups are responsible for interactions of metal ions with the melanin molecule. Complexes of melanins isolated from dark and red human hair show structural differences when analysed by IR spectroscopy. Conclusions from these investigations assist in the differentiation of structures of analysed hair melanins. IR spectral analysis of melanin samples and their complexes suggest that melanin samples obtained from red hair may contain eumelanin.

Laser desorption/ionisation mass spectrometry in the study of natural and synthetic melanins. III. Human hair melanins

Four samples of natural melanin extracted from red, fair, black and brown human head hair were studied by both laser desorption/ionisation (LDI) and matrix-assisted laser desorption/ionisation (MALDI) methods. Clear differences were found among the LDI and MALDI mass spectra of the four melanins. In red hair melanin, there was a major peak at m/z 842 attributed to an oligomeric cluster, together with lower-intensity peaks in the range 4000‐5000 Da. In fair hair melanin, only species with molecular masses from 300 to 600 Da were evidenced. In black hair melanin, clusters up to 25,000 Da were detectable, and in brown hair melanin, there were two main oligomeric clusters in the ranges 600‐900 Da and 3000‐5000 Da, respectively, and a large oligomer distribution from 11,000 to 16,000 Da. It is concluded that there is an increase in relative molecular masses of melanins on passing from fair to black hair, suggesting that in “dark” hair the colour is related to melanins with a higher degree of polymerisation.

A Study on Isolation and Solubilization of Human Hair Melanin and its Application for the Colorimetric Determination of Melanin in the Hair Bleached in Various Degrees

Melanins are widely distributed in the animal and vegetable kingdoms, and are insoluble polymeric pigment which contributes mainly to the color of our skin and hair. In this study, various conditions of hydrolysis with hydrochloric acid were examined in details to extract melanin effectively from human hair with least modifcation. As a result, HCl-refluxing for 24 hours was found to be the most desirable method for the extraction of melanin having almost constant C/N ratio and absorption at 400nm. Various solvents were also investigated to solubilize the extracted melanin and solution of dimethyl n-undecyl n-dodecyl ammonium hydroxide in toluene (“Soluene 100”) and aqueous solution of tetramethyl ammonium hydroxide were found to satisfy the requirement. This made it possible to detrmine the melain contents in hair samples bleached in various degrees by using colorimetry.