Physicochemical characteristics and antioxidant activity of arginine-modified melanin from Lachnum YM-346

Characterization, physicochemical properties, antioxidant activity and hypolipidemic activities of a polysaccharides from Lachnum YM40

LEP-1a, a new polysaccharide fraction isolated and purified from Lachnum YM40, has a molecular weight of 24.29 kDa. LEP-1a's chemical composition investigation showed that mannose, galactose, and glucose made up the majority of its cosmetics. The methylation, nuclear magnetic resonance, and Fourier transform infrared investigations demonstrated that the (1 → 2)-β-D-Galp, (1 → 2,6)-α-D-Manp, glycosidic connections of LEP-1a were comprised of 1→)-α-D-Manp, (1 → 4)-α-D-Galp, (1 → 6)-α-D-Manp, (1 → 2)-β-D-Glcp, (1 → 4)-β-D-Glcp, (1 → 2)-α-D-Manp, and (1 → 3, 6)-β-D-Manp. LEP-1a has a linear microscopic morphology, as demonstrated by atomic force microscopy, scanning electron microscopy, and rheological property investigation. Moreover, the polysaccharide LEP-1a displayed bile acid- and cholesterol-binding capacities and inhibitory activity on lipase.

Neuroprotective effects of melanins and melanin derivatives from Calvatia Craniiformis and Xylaria plebeja against Parkinsonian toxins

Fungal melanins have remarkable bioactivities, but their practical applications are limited, partly due to their hydrophobic nature. Melanin modification with amino acids was reported to improve their water solubility. This research aimed to extract, and modify the melanins from Calvatia craniiformis and Xylaria plebeja with arginine, and to evaluate their neuroprotective effects against Parkinsonian toxins. MTT assay showed that all melanins and melanin derivatives could protect SH-SY5Y neuroblastoma cells from 1 mM H2O2. Xylaria plebeja melanin and melanin derivative at 100 µg/mL increased the cell viability about 16.0% compared to the negative control, whereas C. craniiformis melanin and its modified form enhanced the cell viability by 18.4% and 8.3%, respectively and that of the positive control (20 µM resveratrol) was 35.5%. Regarding neuroprotective effects against MPTP, the positive control, C. craniiformis melanin, and modified melanin increased the cell viability with approximately 5.0%, but that of X. plebeja melanin and modified melanin were 13.0%. Both melanins and melanin derivatives from C. craniiformis and X. plebeja showed significant neuroprotective effects against H2O2. However, only X. plebeja melanin and modified melanin displayed significant neuroprotective effects against MPTP and therefore they would be potential materials for follow-up research in Parkinson's disease prevention.

Biocompatible melanin from the marine black yeast Hortaea werneckii R23 with antioxidant and photoprotection property

Pigments from diverse sources have a great deal of interest due to its multifaceted applications. Hence, this study reports the physicochemical and functional characterization of the black pigment melanin from the marine black yeast Hortaea werneckii R23. In the present study, Hortaea werneckii R23, produced a black pigment in the yeast biomass. The pigment was extracted from the harvested yeast biomass and followed by pigment purification, characterization and identification was done. Physicochemical characterization of the pigment showed acid precipitation, alkali solubilization, insolubility in most organic solvents and water. The black pigment was confirmed as melanin based on ultraviolet-visible spectroscopy, Fourier-transform infrared, and Nuclear magnetic resonance spectroscopy analyses. Furthermore, the analyses of the elemental composition indicated that the pigment possessed a moderately high percentage of nitrogen and also detectable proportion of sulfur. All these Physicochemical properties indicated that H. werneckii melanin (HwM) mostly consisted of eumelanin. HwM exhibited strong antioxidant potential as reactive oxygen species (ROS) scavenger by in vitro DPPH (1,1-diphenyl-2-picryl hydrazyl) and ABTS (2,2-azinobis-3-ethyl-benzothiozoline-6-sulphonic acid) radical scavenging assay, and lipid peroxidation assay. The photoprotectant role of HwM on UV-irradiated human epithelial cells (HEp-2) revealed its potential effect in photoprotection. In addition, cytotoxicity study by XTT and SRB assay confirmed its biocompatibility with HEp-2 cells. From these findings, it is evident that the HwM from the marine black yeast possesses strong antioxidant and photoprotectant activity, moreover, it is biocompatible to human epithelial cells. So HwM could be used as a protective agent against oxidative stress associated disorders in an environment-friendly perspective.

Antioxidant, neuroprotective, and neuroblastoma cells (SH-SY5Y) differentiation effects of melanins and arginine-modified melanins from Daedaleopsis tricolor and Fomes fomentarius

BACKGROUND

Microbial melanins possess a broad spectrum of biological activities. However, there is little understanding of their neuroprotective and neuronal cell differentiation properties. This study aimed to extract, purify, and modify melanins from two medicinal fungi (Daedaleopsis tricolor and Fomes fomentarius), and to evaluate their antioxidant activity, as well as their cell protective ability against neurotoxins. In addition, the study also investigated the feasibility of combining melanins or modified melanins with retinoic acid (RA) to induce neuronal differentiation.

METHODS

Melanin was extracted and purified using alkaline acid-based methods. Antioxidant activities and neuroprotective effects were evaluated using the DPPH (1,1-diphenyl-2-picrylhydrazyl) and MTT (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) assays, respectively. In addition, morphological changes of SH-SY5Y cells were recorded by using a Pannoramic MIDI scanner.

RESULTS

All melanins and arginine-modified melanins displayed mild DPPH scavenging activities, which were statistically lower than that of ascorbic acid (p < 0.05). In terms of neuroprotection, both melanins and arginine-modified melanins exhibited significant cell protection against H2O2 after 24 h exposure (p < 0.05). Notably, there is no significant difference between F. fomentarius melanin and its modified form as they both increased cell viability by about 20%. Contrarily, while D. tricolor melanin enhanced the cell viability with 16%, its modified form increased the cell viability with 21%. These activities, however, are significantly lower than the positive control (N-acetylcysteine, p < 0.05). Regarding MPTP, only the arginine-modified melanins of the two fungi significantly protected the cells after 24 h exposure to the toxin (p < 0.05). Specifically, F. fomentarius and D. tricolor modified melanins enhanced the cell viability with 10.2% and 11.1%, respectively, whereas that of the positive control was 13.2%. Interestingly, combining RA (10 µM) with 20 µg/mL of either F. fomentarius, or especially D. tricolor arginine-modified melanin, significantly promoted neuroblastoma cell differentiation into mature neuronal cells compared to using RA alone (p < 0.05).

CONCLUSIONS

The arginine-modified melanins of D. tricolor and F. fomentarius have potential for neuroprotection against Parkinsonian neurotoxins. In addition, the arginine-modified melanin of D. tricolor may serve as an excellent material for research in neuroblastoma treatment.

Anti-ultraviolet, antibacterial, and biofilm eradication activities against Cutibacterium acnes of melanins and melanin derivatives from Daedaleopsis tricolor and Fomes fomentarius

Fomes fomentarius and Daedaleopsis tricolor produced significant amounts of water-insoluble melanins, and our previous study successfully enhanced their water solubility by arginine modification. This research aimed to investigate the anti-ultraviolet, antibacterial, and biofilm eradication activities of both the melanins and arginine-modified melanin (melanin derivatives) from these two fungi against an acne-causing bacterium (Cutibacterium acnes). Apart from these, the cytotoxicity of the melanins and melanin derivatives on human skin cells was also evaluated. Melanin derivatives of both two fungi showed significantly higher antibacterial and biofilm eradication activities compared with their original forms. Specifically, the MIC50 values of the melanin derivatives (1,000 μg/mL) are the same as those of erythromycin. Regarding biofilm eradication capacity, the MBEC50 value of D. tricolor melanin derivative (250 μg/mL) was just half of both erythromycin and F. fomentarius melanin derivative. However, it required a 2-fold higher concentration of melanin derivatives than erythromycin to inhibit 90% of the bacterial population and eradicate 90% of their biofilm. Regarding anti-ultraviolet activity, blending melanins or melanin derivatives with a moisturizer/sunscreen enhanced their UV light absorption and the sun protection factor (SPF) values. In addition, melanins showed better effects than their derivatives, and those of D. tricolor were better than F. fomentarius. Remarkably, adding D. tricolor melanin (10%) to a Nivea pure cream could turn this cream into a broad-spectrum sunscreen, with its SPF value and critical wavelength increasing from 7.74 and 338.67 to 14.02 and 377.0, respectively. In addition, adding melanin or a melanin derivative of D. tricolor to an Olay sunscreen enhanced the SPF and the critical wavelength of the sunscreen from 17.25 and 371.67 to 23.82 and 374 and 23.38 and 372, respectively. Notably, melanins and melanin derivatives showed no toxicity in human fibroblasts. The obtained data suggest that arginine modification significantly enhanced the antibacterial and biofilm eradication activities of melanins from D. tricolor and F. fomentarius. However, this is not the case when it comes to their anti-ultraviolet activities. In addition, melanin and melanin derivatives from D. tricolor are potential candidates for anti-acne sunscreen products and are worth further investigation.

Fermented Tea as a Food with Functional Value-Its Microbiological Profile, Antioxidant Potential and Phytochemical Composition

Kombucha is a fermented tea drink produced by a symbiotic culture of bacteria and yeast, known as SCOBY. Its base has traditionally been black tea, which has been recognized for its health-promoting properties, particularly its antioxidant activity based on its high content of pol-yphenolic compounds. A number of previous studies have demonstrated the equally favourable biochemical and phytochemical composition of green tea. The aim of this study was to analyse and compare the basic biochemical composition, microbiological composition and antioxidant properties of black and green tea-based Kombucha. The green tea-based Kombucha showed a quantitatively more abundant microbial composition (Lactic Acid Bacteria, Acetobacter sp., Yeast), a higher reducing potential (FRAP-4326.58 Fe(II)µM/L) and a higher content of total polyphenols (23.84 mg GAE/100 mL, reducing sugars (3212.00 mg/100 mL) as well as free amino acids (849.00 mg GLY/mL). Kombucha made from black tea, on the other hand, showed a higher anti-oxidant potential (1.17 Trolox (mM) TEAC), neutralising the DPPH radical at 94.33% and ABTS at 97.74%. It also had a higher level of acetic acid (0.08 g/100 mL). Green tea kombucha had a higher scavenging capacity of 90.6% for superoxide radical (O2-) and 69.28% for hydroxyl radical (·OH) than black tea kombucha. In the present study, both kombucha drinks tested were shown to be source of potent antioxidants. In addition, green tea, as a kombucha base, has proven to be as beneficial a raw material that will provide full nutritional and health-promoting values as traditional kombucha.

Comprehensive Regulation of Liquid-Liquid Phase Separation of Polypeptides

The elucidation of the molecular driving forces responsible for Liquid-liquid Phase Separation (LLPS) of proteins and nucleic acids within living cells is crucial for understanding its biological functions and its role in related diseases. In the present study, we investigated the regulation of LLPS in a series of polypeptides with repetitive proline and arginine (PR) sequences by modifying their length and the salt concentration in the solution. Our findings indicate that higher salt concentrations are necessary for LLPS of repetitive PR peptides longer than eight PRs, which emerges as a threshold value. To pinpoint the molecular forces driving the LLPS in peptides, we sequentially introduced various concentrations of hydrophobic disruptors, such as 1,6-hexanediol, and electrostatic regulators, such as ethyl alcohol and 6-Aminocaproic acid. We further modulated the electrostatic interaction by introducing ethyl alcohol and 6-Aminocaproic acid to alter the dielectric constant of the solution. The inclusion of ethyl alcohol intensified the electrostatic interaction between arginine molecules, facilitating LLPS of PR15, while 6-Aminocaproic acid yielded the reverse effect. We deduced that the phase separation in peptide systems is conjointly driven by hydrophobicity and electrostatic interactions. These insights can guide the regulation of LLPS in other peptide and protein systems, and could be pivotal in addressing abnormal aggregations of proteins and nucleic acids.

Recent Advances in Characterization of Melanin Pigments in Biological Samples

The melanin pigments eumelanin (EM) and pheomelanin (PM), which are dark brown to black and yellow to reddish-brown, respectively, are widely found among vertebrates. They are produced in melanocytes in the epidermis, hair follicles, the choroid, the iris, the inner ear, and other tissues. The diversity of colors in animals is mainly caused by the quantity and quality of their melanin, such as by the ratios of EM versus PM. We have developed micro-analytical methods to simultaneously measure EM and PM and used these to study the biochemical and genetic fundamentals of pigmentation. The photoreactivity of melanin has become a major focus of research because of the postulated relevance of EM and PM for the risk of UVA-induced melanoma. Our biochemical methods have found application in many clinical studies on genetic conditions associated with alterations in pigmentation. Recently, besides chemical degradative methods, other methods have been developed for the characterization of melanin, and these are also discussed here.

Physicochemical properties, molecular structure, antioxidant activity, and biological function of extracellular melanin from Ascosphaera apis

Ascosphaera apis spores containing a dark-colored pigment infect honeybee larvae, resulting in a large-scale collapse of the bee colony due to chalkbrood disease. However, little is known about the pigment or whether it plays a role in bee infection caused by A. apis. In this study, the pigment was isolated by alkali extraction, acid hydrolysis, and repeated precipitation. Ultraviolet (UV) analysis revealed that the pigment had a color value of 273, a maximum absorption peak at 195 nm, and a high alkaline solubility (7.67%) and acid precipitability. Further chemical structure analysis of the pigment, including elemental composition, Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, mass spectrometry, and nuclear magnetic resonance (NMR), proved that it was a eumelanin with a typical indole structure. The molecular formula of melanin is C₁₀H₆O₄N₂, and its molecular weight is 409 Da. Melanin has hydroxyl, carboxyl, amino, and phenolic groups that can potentially chelate to metal ions. Antioxidant function analyses showed that A. apis melanin had a high scavenging activity against superoxide, hydroxyl, and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals, and a high reducing ability to Fe³⁺. Indirect immunofluorescence assay (IFA), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) analyses showed that A. apis melanin was located on the spore wall. The spore wall localization, antioxidant activity, and metal ion chelating properties of fungal melanin have been suggested to contribute to spore pathogenicity. However, further infection experiments showed that melanin-deficient spores did not reduce the mortality of bee larvae, indicating that melanin does not increase the virulence of A. apis spores. This study is the first report on melanin produced by A. apis, providing an important background reference for further study on its role in A. apis.

Pyomelanin produced by Streptomyces sp. ZL-24 and its protective effects against SH-SY5Y cells injury induced by hydrogen peroxide

A soluble melanin pigment produced by Streptomyces sp. ZL-24 was purified and named StrSM. The elemental analysis of StrSM showed it consists of carbon, hydrogen, and oxygen. The spectrum analysis, including ultraviolet-visible absorption spectrum, Fourier-transform infrared spectrum, and pyrolysis-gas chromatography-mass spectrometry, indicated that StrSM might be pyomelanin. High performance liquid chromatography and liquid chromatography-mass spectra analysis of intermediate metabolite showed the presence of homogentisic acid (HGA). Moreover, the enzyme 4-hydroxyphenylpyruvate dioxygenase, involved in HGA biosynthesis, showed high activity during melanin production. Subsequently, a tyrosinase gene (melC2) and hydroxyphenylpyruvate dioxygenase gene double mutant demonstrated StrSM is pyomelanin. In vitro bioactivity assay showed that StrSM had excellent protective capability against SH-SY5Y cell oxidative injury. To our knowledge, the results firstly provide comprehensive data on Streptomyces pyomelanin identification and a promising candidate compound to treat oxidative injury of neurocytes.

Synthesis, anticancer evaluation and mechanism studies of novel indolequinone derivatives of ursolic acid

A series of novel indolequinone derivatives of ursolic acid bearing ester, hydrazide, or amide moieties were designed, synthesized, and screened for their in vitro antiproliferative activities against three cancer cell lines (MCF-7, HeLa, and HepG2) and a normal gastric mucosal cell line (Ges-1). A number of compounds showed significant activity against tested cancer cell lines. Among them, compound 6t exhibited the most potent activity against three cancer cell lines with IC50 values of 1.66 ± 0.21, 3.16 ± 0.24, and 10.35 ± 1.63 µM, respectively, and considerably lower cytotoxicity to Ges-1 cells. Especially, compound 6t could arrest cell cycle at S phase, suppress the migration of MCF-7 cells, elevate intracellular reactive oxygen species (ROS) level, and decrease mitochondrial membrane potential. Western blot analysis showed that compound 6t upregulated Bax, cleaved caspase-3/9, cleaved PARP levels and downregulated Bcl-2 level of MCF-7 cells. All these results indicated that compound 6t could significantly induce the apoptosis of MCF-7 cells. Meanwhile, compound 6t markedly decreased p-AKT and p-mTOR expression, which revealed that compound 6t probably exerted its cytotoxicity through targeting PI3K/AKT/mTOR signaling pathway. Therefore, compound 6t could be a promising lead for the discovery of novel anticancer agents.

Preparation and Characterization of Carboxymethyl Cellulose-Based Bioactive Composite Films Modified with Fungal Melanin and Carvacrol

Preparation of biodegradable packaging materials and valorisation of food industry residues to achieve "zero waste" goals is still a major challenge. Herein, biopolymer-based (carboxymethyl cellulose-CMC) bioactive films were prepared by the addition, alone or in combination, of carvacrol and fungal melanin isolated from champignon mushroom (Agaricus bisporus) agro-industrial residues. The mechanical, optical, thermal, water vapour, and UV-Vis barrier properties were studied. Fourier-transform infrared (FT-IR) spectroscopy studies were carried out to analyse the chemical composition of the resulting films. Antibacterial, antifungal, and antioxidant activities were also determined. Both CMC/melanin and CMC/melanin/carvacrol films showed some antimicrobial activity against Escherichia coli, Staphylococcus aureus, and Candida albicans. The addition of melanin increased the UV-blocking, mechanical, water vapour barrier, and antioxidant properties without substantially reducing the transparency of the films. The addition of carvacrol caused loss of transparency, however, composite CMC/melanin/carvacrol films showed excellent antioxidant activity and enhanced mechanical strength. The developed bioactive biopolymer films have a good potential to be green bioactive alternatives to plastic films in food packaging applications.

Comparison of physicochemical and biochemical properties of natural and arginine-modified melanin from medicinal mushroom Ganoderma lucidum

Melanin is a hydrophobic biomolecule produced widely in fungi. Compared with other fungi, health benefits have been associated with medicinal mushrooms, which may provide an excellent source of natural melanin. Nevertheless, the hydrophobicity of melanin may limit its applications. Consequently, the present study was carried out on isolation of melanin from the medicinal mushroom Ganoderma lucidum (GLM) and modification with arginine to improve its solubility. The physicochemical and biochemical properties of melanin were evaluated including structural characterization, solubility, stability, antioxidant activities, and inhibitory effect on pancreatic lipase activity. Arginine-modified melanin showed better solubility, higher color value, stronger antioxidant activity, and stronger inhibitory effect on pancreatic lipase activity in vitro than GLM. In addition, both have good stability in the dark and natural light. These results opened possibilities for providing an excellent source of natural melanin in health food or food additives fields.

Whey Protein Concentrate/Isolate Biofunctional Films Modified with Melanin from Watermelon (Citrullus lanatus) Seeds

Valorization of food industry waste and plant residues represents an attractive path towards obtaining biodegradable materials and achieving "zero waste" goals. Here, melanin was isolated from watermelon (Citrullus lanatus) seeds and used as a modifier for whey protein concentrate and isolate films (WPC and WPI) at two concentrations (0.1% and 0.5%). The modification with melanin enhanced the ultraviolet (UV) blocking, water vapor barrier, swelling, and mechanical properties of the WPC/WPI films, in addition to affecting the apparent color. The modified WPC/WPI films also exhibited high antioxidant activity, but no cytotoxicity. Overall, the effects were melanin concentration-dependent. Thus, melanin from watermelon seeds can be used as a functional modifier to develop bioactive biopolymer films with good potential to be exploited in food packaging and biomedical applications.

Biotransformation of Flaxseed Oil Cake into Bioactive Camembert-Analogue Using Lactic Acid Bacteria, Penicillium camemberti and Geotrichum candidum

This study aimed at investigating the antioxidant activity, oxidative stability, physicochemical and microbial changes of innovative vegan Camembert-analogue based on flaxseed oil cake (FOC) which was produced using lactic acid bacteria (LAB), mold Penicillium camemberti (PC) and yeast Geotrichum candidum (GC). Two variants were prepared, namely with LAB + PC and LAB + PC + GC. After fermentation for 24 h at room temperature, the samples were stored for 14 days at 12 °C and maturated for 14 days at 6 °C. Changes in microbial population, polyphenolics, flavonoids, radical scavenging capacity were evaluated. Additionally, textural changes, pH, acidity, levels of proteins, free amino acids, reducing sugars, oil content and its oxidative stability were determined. Results showed that LAB as well as fungi were capable of growing well in the FOC without any supplementation and the products were characterized by a high antioxidant potential (high polyphenolics and flavonoids contents as well as 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), superoxide (O2-) and hydroxyl (·OH) radicals scavenging activity). This study has demonstrated that bioactivity as well as the physicochemical properties depend on the starter culture used. Due to functional and biochemical characteristics conferred to the obtained Camembert-analogues, the use of P. camemberti and G. candidum showed a potential for industrial application. There is a potential for these products to be used where non-dairy alternatives are desired.

From Extraction to Advanced Analytical Methods: The Challenges of Melanin Analysis

The generic term "melanin" describes a black pigment of biological origin, although some melanins can be brown or even yellow. The pigment is characterized as a heterogenic polymer of phenolic or indolic nature, and the classification of eu-, pheo- and allo- melanin is broadly accepted. This classification is based on the chemical composition of the monomer subunit structure of the pigment. Due to the high heterogeneity of melanins, their analytical characterization can be a challenging task. In the present work, we synthesized the current information about the analytical methods which can be applied in melanin analysis workflow, from extraction and purification to high-throughput methods, such as matrix-assisted laser desorption/ionization mass-spectrometry or pyrolysis gas chromatography. Our thorough comparative evaluation of analytical data published so far on melanin analysis has proven to be a difficult task in terms of finding equivalent results, even when the same matrix was used. Moreover, we emphasize the importance of prior knowledge of melanin types and properties in order to select a valid experimental design using analytical methods that are able to deliver reliable results and draw consistent conclusions.

The Ustilago maydis null mutant strains of the RNA-binding protein UmRrm75 accumulate hydrogen peroxide and melanin

Ustilago maydis is a dimorphic fungus that has emerged as a model organism for the study of fungal phytopathogenicity and RNA biology. In a previous study, we isolated the U. maydis UmRrm75 gene. The deletion of the UmRrm75 gene affected morphogenesis and pathogenicity. UmRrm75 gene encodes a protein containing three RNA recognition motifs. Here we determined that UmRrm75 has chaperone activity in Escherichia coli using the transcription anti-termination assay. Subsequently, we analyzed the growth of ΔUmRrm75 mutants at 15 °C and 37 °C, observing that mutant strains had reduced growth in comparison to parental strains. UmRrm75 gene expression was induced under these non-optimal temperatures. ΔUmRrm75 mutant colonies displayed a dark-brown color at 28 °C, which was confirmed to be melanin based on spectroscopic analysis and spectrometric data. Furthermore, ΔUmRrm75 mutant strains showed the presence of peroxisomes, and increased H₂O₂ levels, even at 28 °C. The ΔUmRrm75 mutant strains displayed a higher expression of redox-sensor UmYap1 gene and increased catalase activity than the parental strains. Our data show that deletion of the UmRrm75 gene results in higher levels of H₂O₂, increased melanin content, and abiotic stress sensitivity.

Characterization of natural melanin from Auricularia auricula and its hepatoprotective effect on acute alcohol liver injury in mice

This study characterized the natural melanin from Auricularia auricula and investigated its hepatoprotective effect on mice with acute alcoholic liver injury. The characterization of the melanin was analyzed based on elemental analysis, gel permeation chromatography (GPC), UV-visible spectroscopy (UV-visible), infrared spectrum (IR) and nuclear magnetic resonance spectra (NMR). To determine the liver protective effect of Auricularia auricula melanin, mice were administered with the melanin once daily for 3 weeks before ethanol induced liver injury. Biochemical parameters of liver function, histopathological sections, mRNA and protein expression of antioxidant enzyme were compared between mice with or without the melanin administered. Results showed that A. auricula melanin was a eumelanin and the average molecular weight was 48.99 kDa. The melanin can protect the mice from ethanol-induced liver injury by extending the duration of the righting reflex, and shortening the duration of the recovery. The liver index, serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), γ-glutamyl transpeptidase (γ-GT) and liver malondialdehyde (MDA) levels in mice treated with the melanin were significantly decreased. At the same time, the levels of liver alcohol dehydrogenase (ADH), and antioxidase such as catalase (CAT), and superoxide dismutase (SOD) were increased. Its protective effect may be related to the activation of nuclear factor E2-related factor 2 (Nrf2) and its downstream antioxidant enzymes such as glutamate cysteine ligase catalytic (GCLC), glutamate cysteine ligase modifier (GCLM), and NADP(H) quinine oxidoreductase 1 (NQO-1). These results suggested that A. auricula melanin may be an effective strategy to alleviate alcohol-induced liver damage.

Study on the Preparation and Chemical Structure Characterization of Melanin from Boletus griseus

In this study, melanin (BgM) was obtained from Boletus griseus. The chemical composition and structure of BgM were characterized by UV-visible absorption spectrum, Fourier transform infrared spectrum, elemental analysis, nuclear magnetic resonance, pyrolysis gas chromatography mass spectrometry, and ultra-performance liquid chromatography–high resolution mass spectrometry. The percentage contents of C, H, N, S and O elements were 56.38%, 5.86%, 6.17%, 2.44%, and 28.04%, and the S/N and C/N ratios were 0.17 and 10.66, respectively. The UV-vis spectrum of BgM showed a maximum absorption peak at 214 nm. Characteristic absorption peaks were observed at 3426, 1600 and 1105 cm⁻¹, and BgM contained phenolic hydroxyl, amidogen, carbonyl, methylene, and methyl groups. Moreover, BgM is an eumelanin, and its main skeleton has both a benzene ring and an indole, and the branched chain mainly consists of alkanes, alcohols, and fatty acids. BgM was hydrolyzed by H₂O₂ and four compounds were tentatively analyzed from the UPLC-MS/MS profile. The chemical structure of BgM was characterized as 5,6-dihydroxyindole eumelanin, and the condensed molecular formula is [C₂₈(OR₁)₄(OR₂)₃H₁₁O₆N₄]_n.

Antitumor effects of melanin from Lachnum YM226 and its derivative in H22 tumor-bearing mice

In the present study, we investigated the anti-tumor activities of the intracellular homogeneous melanin (LM) of Lachnum YM226 and its derivative (ALM) on liver cancer using murine H22 hepatocarcinoma model. The results showed that LM and ALM (50 and 200 mg kg-1) could effectively inhibit tumor growth of H22 tumour-bearing mice. The body weight, liver, spleen and thymus indices also improved in the LM and ALM treated groups. Moreover, the levels of alanine aminotransferase (ALT), aspartate aminotransaminase (AST), alkaline phosphatase (ALP), creatinine (CRE), blood urea nitrogen (BUN) and uric acid (UA) were lowered. Serum cytokines of interleukin-2 (IL-2), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α) and interferon-γ (IFN-γ) were increased on LM and ALM administration, while LM and ALM significantly decreased the vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) levels. The H&E staining indicated that LM and ALM exhibited antitumor activity in vivo by promoting apoptosis and inhibiting angiogenesis. The anti-tumor effect of ALM was more significant than that of LM for the same dose. In summary, the findings demonstrated that LM and ALM might be promising candidates for the prevention and treatment of HCC.

Synergistic antitumor effect of polysaccharide from Lachnum sp. in combination with cyclophosphamide in hepatocellular carcinoma

Combination therapy with chemotherapeutics is attracting increasing attention as an important treatment option for hepatocellular carcinoma (HCC) due to its complex pathological characteristics. In this study, as a new therapy strategy, combination treatment of LEP-2a (a non-toxic polysaccharide from Lachnum sp.) with cyclophosphamide (CTX) was investigated. Results showed that combination treatment with LEP-2a and CTX processed a significantly synergistic anti-tumor effect in H22 tumor-bearing mice through Fas/FasL mediated caspase-dependent death pathway and mitochondria apoptosis pathway. Moreover, our study indicated that LEP-2a played a crucial role in enhancement of immune response, inhibition of tumor angiogenesis and down-regulation of survival associated proteins. Notably, side effects induced by CTX were relieved after LEP-2a treatment. These results support the conception that LEP-2a has the potential as an ideal adjuvant agent for a more effective combination therapy with CTX against HCC.

Protection effect of intracellular melanin from Lachnum YM156 and Haikunshenxi capsule combination on adenine-induced chronic renal failure in mice

This study aimed to elucidate the therapeutic effects of oral administration of intracellular melanin from Lachnum YM156 (LIM) on chronic renal failure (CRF) in mice. The cytotoxicity of LIM was evaluated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. CRF was induced in mice by chronic dietary adenine intake. We have used this intervention to explore the effects of oral treatment with LIM (100 and 200 mg kg^-1) in CRF mice. The treatment with LIM alone and a combination of Haikunshenxi capsule (HC) add LIM increased the concentration levels of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-PX), and glutathione reductase (GSH), reduced malonaldehyde (MDA) in the nephridial tissues and also reduced the nephridial levels of tumor necrosis factor (TNF)-α, interleukin-1β (IL-1β), and interleukin (IL)-6, and the activities of inducible nitric oxide synthase (iNOS). Interestingly, the HC and LIM combination produced a higher therapeutic effect than HC alone. The mechanism of the reported salutary effects of LIM in adenine-induced CRF is associated with amelioration of the adenine induced inflammation and oxidative stress. The present findings recommend that LIM is a useful natural product which can be used to enhance the protection function of HC in CRF mice.

Antioxidant activity of a Lachnum YM226 melanin-iron complex and its influence on cytokine production in mice with iron deficiency anemia

The present study aims to investigate the protective effects of an orally administered Lachnum YM226 melanin-iron complex (LM-Fe) against iron deficiency anemia (IDA) in mice. The IDA mouse model was established by feeding mice with iron-deficient food. Different doses of LM-Fe were given to the anaemic mice via intragastric administration, with FeCl3 and FeSO4 used as positive controls. After the iron supplement administration, it was observed that LM-Fe could significantly improve the decreased haemoglobin (Hb) level, and normalize the serum iron (SI) level, total iron-binding capacity (TIBC) and serum ferritin (SF) of the anaemic mice in a dose-dependent manner. In addition, treatment with LM-Fe significantly increased the antioxidant enzyme activities of superoxidase dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) in plasma to normal or better. Furthermore, the levels of tumour necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and interleukin-6 (IL-6) were obviously decreased in the LM-Fe supplemented groups compared with the model group, while the level of interleukin-2 (IL-2) was significantly increased. In conclusion, LM-Fe was efficient at ameliorating the anemia symptoms, improving the activities of antioxidant enzymes and adjusting the immune dysfunction of anaemic mice. Thus, these results demonstrated that LM-Fe might be exploited as an efficient and multifunctional iron supplement.

Structural characterization, molecular modification and hepatoprotective effect of melanin from Lachnum YM226 on acute alcohol-induced liver injury in mice

In this paper, we obtained the possible structural formula of the intracellular melanin of Lachnum YM226 and evaluated the protective effect of this melanin and itsd-glucosamine-modified product on acute alcohol-induced liver injury in mice.

On-column enzymatic synthesis of melanin nanoparticles using cryogenic poly(AAM-co-AGE) monolith and its free radical scavenging and electro-catalytic properties

“Novel approach for biosynthesis of melanin nanoparticles by sequestrial biotransformation of l-DOPA using immobilized tyrosinase enzyme in macroporous poly(AAm-co-AGE) monolith”.

Isolation, purification, and anti-aging activity of melanin from Lachnum singerianum

Intracellular melanin from Lachnum singerianum YM296 (LIM) was obtained by the method of microwave-assisted extraction. On the basis of single factor experiment, the optimum microwave-assisted extraction conditions of LIM using Box-Behnken design were as follows: NaOH concentration, 1.05 mol/L; ratio of raw material to liquid ratio, 1:14.72 (g/mL); microwave time, 118.70 s; and microwave power, 320 W. Under these conditions, the extraction yield of LIM was 11.08 %, and 40.43 % higher than that of extraction by alkali extraction and acid precipitation. The results showed that microwave-assisted extraction could increase the extraction yield of LIM. Three homogeneous components were fractionated from LIM by Sephadex G-15 column. LIM-a was the main homogeneous component, accounting for 75.7 % of the total content of the homogeneous components. Aged mice model were induced by injecting D-galactose, and the aged mice were given LIM-a of different dosages, respectively. The results showed that LIM-a can significantly increase body weight, thymus indexes, and spleen indexes of the aged mice; effectively elevate the levels of SOD, GSH-PX, and CAT; and decrease the level of MDA in mice liver homogenate, brain homogenate, and serum, indicating that LIM-a had significant anti-aging activity.