Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 830
Filtrar
1.
J Microbiol Biotechnol ; 29(6): 973-983, 2019 Jun 28.
Artigo em Inglês | MEDLINE | ID: mdl-31216793

RESUMO

It is well known that iron is critical for bacterial growth and pathogenic virulence. Due to chemical similarity, Ga3+ competes with Fe3+ for binding to compounds that usually bind Fe3+, thereby interfering with various essential biological reactions. In our present study, gallium(III) nitrate [Ga(NO3)3] could repress the growth of V. splendidus Vs without complete inhibition. In the presence of Ga(NO3)3, the secretion of homogentisic acid-melanin (HGAmelanin) in V. splendidus Vs cells could be increased by 4.8-fold, compared to that in the absence of Ga(NO3)3. HGA-melanin possessed the ability to reduce Fe3+ to Fe2+. In addition, HGA-melanin increased the mRNA levels of feoA and feoB, genes coding Fe2+ transport system proteins to 1.86- and 6.1-fold, respectively, and promoted bacterial growth to 139.2%. Similarly, the mRNA expression of feoA and feoB was upregulated 4.11-fold and 2.71-fold in the presence of 640 µM Ga(NO3)3, respectively. In conclusion, our study suggested that although Ga(NO3)3 could interfere with the growth of V. splendidus Vs, it could also stimulate both the production of Fe3+-reducing HGA-melanin and the expression of feoA and feoB , which facilitate Fe2+ transport in V. splendidus Vs.


Assuntos
Gálio/farmacologia , Ferro/metabolismo , Vibrio/efeitos dos fármacos , Proteínas de Bactérias/genética , Transporte Biológico/efeitos dos fármacos , Proteínas de Transporte de Cátions/genética , Relação Dose-Resposta a Droga , Regulação Bacteriana da Expressão Gênica/efeitos dos fármacos , Ácido Homogentísico/química , Ácido Homogentísico/metabolismo , Ácido Homogentísico/farmacologia , Melaninas/química , Melaninas/metabolismo , Melaninas/farmacologia , Oxirredução , Sideróforos/metabolismo , Vibrio/crescimento & desenvolvimento , Vibrio/metabolismo
2.
Nat Commun ; 10(1): 2250, 2019 05 21.
Artigo em Inglês | MEDLINE | ID: mdl-31113945

RESUMO

Recent progress has been made in paleontology with respect to resolving pigmentation in fossil material. Morphological identification of fossilized melanosomes has been one approach, while a second methodology using chemical imaging and spectroscopy has also provided critical information particularly concerning eumelanin (black pigment) residue. In this work we develop the chemical imaging methodology to show that organosulfur-Zn complexes are indicators of pheomelanin (red pigment) in extant and fossil soft tissue and that the mapping of these residual biochemical compounds can be used to restore melanin pigment distribution in a 3 million year old extinct mammal species (Apodemus atavus). Synchotron Rapid Scanning X-ray Fluorescence imaging showed that the distributions of Zn and organic S are correlated within this fossil fur just as in pheomelanin-rich modern integument. Furthermore, Zn coordination chemistry within this fossil fur is closely comparable to that determined from pheomelanin-rich fur and hair standards. The non-destructive methods presented here provide a protocol for detecting residual pheomelanin in precious specimens.


Assuntos
Extinção Biológica , Fósseis , Melaninas/análise , Animais , Cabelo/química , Melaninas/química , Murinae , Imagem Óptica/instrumentação , Imagem Óptica/métodos , Paleontologia/métodos , Análise Espectral/instrumentação , Análise Espectral/métodos , Enxofre/química , Zinco/química
3.
Environ Health Prev Med ; 24(1): 36, 2019 May 17.
Artigo em Inglês | MEDLINE | ID: mdl-31101002

RESUMO

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.


Assuntos
Melaninas/química , Molibdênio/química , Poluentes Químicos da Água/química , Adsorção , Animais , Melaninas/metabolismo , Camundongos , Camundongos Pelados , Camundongos Transgênicos , Molibdênio/metabolismo , Molibdênio/farmacologia , Pele/química , Pele/efeitos dos fármacos , Pigmentação da Pele/efeitos dos fármacos , Poluentes Químicos da Água/metabolismo , Poluentes Químicos da Água/farmacologia
4.
Nanoscale ; 11(13): 6285-6296, 2019 Mar 28.
Artigo em Inglês | MEDLINE | ID: mdl-30882835

RESUMO

Multimodality therapy under imaging-guidance is significant to improve the accuracy of cancer treatment. In this study, a photoacoustic imaging (PAI)-guided anticancer strategy based on poly-l-lysine functionalized melanin nanoparticles (MNP-PLL) was developed to treat laryngeal squamous cell carcinoma (LSCC). As a promising alternative to traditional therapies for LSCC, MNP-PLL/miRNA nanoparticles were combined with photothermal ablation against primary tumors and miR-145-5p mediated gene therapy for depleting the metastatic potential of tumor cells. Furthermore, taking advantage of the photoacoustic properties of melanin, PAI guided therapy could optimize the time point of NIR irradiation to maximize the efficacy of photothermal therapy (PTT). The in vitro and in vivo results proved that the combined treatments displayed the most significant tumor suppression compared with monotherapy. By integrating thermo-gene therapies into a theranostic nanoplatform, the MNP-PLL/miR-145-5p nanoparticles significantly suppressed the LSCC progression, indicating their great potential use for cancer therapy.


Assuntos
Carcinoma de Células Escamosas/terapia , Terapia Genética , Neoplasias Laríngeas/terapia , Melaninas/química , Nanopartículas/química , Animais , Carcinoma de Células Escamosas/diagnóstico por imagem , Carcinoma de Células Escamosas/patologia , Linhagem Celular Tumoral , Movimento Celular/efeitos dos fármacos , Movimento Celular/efeitos da radiação , Sobrevivência Celular/efeitos dos fármacos , Sobrevivência Celular/efeitos da radiação , Terapia Combinada , Humanos , Raios Infravermelhos , Neoplasias Laríngeas/diagnóstico por imagem , Neoplasias Laríngeas/patologia , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Nus , MicroRNAs/química , MicroRNAs/metabolismo , Microscopia Confocal , Nanopartículas/uso terapêutico , Nanopartículas/toxicidade , Fototerapia , Polilisina/química , Nanomedicina Teranóstica
5.
Artigo em Inglês | MEDLINE | ID: mdl-30897406

RESUMO

Determination of eumelanin and pheomelanin in melanomas that exhibit different pigmentation was carried using a solid-phase extraction (SPE) preparation method based on weak anion exchange chemistry. This extraction significantly enhanced the chromatographic profile obtained by reverse phase high performance liquid chromatography-diode array detection (RP-HPLC-DAD). The SPE method was developed using aqueous standards of melanin markers: thiazole-2,4,5-tricarboxylic acid (TTCA), thiazole-4,5-dicarboxylic acid (TDCA), pyrrole-2,3-dicarboxylic acid (PDCA) and pyrrole-2,3,5-tricarboxylic acid (PTCA) and non-pigmented cell lines spiked with those markers. An excellent average recovery, above 90%, was obtained for the four markers with a relative standard deviation below 7%. We have also optimized the stationary phase and the mobile phase (phosphate concentration and pH) to improve sensitivity and to reduce the analysis time. Elution of the four markers is achieved in 5 min and total analysis of biological samples is completed in 15 min. The quantification limits for TDCA, TTCA, PDCA and PTCA are 60, 50, 47 and 48 ng/mL respectively. Furthermore, DAD detection improves the marker identification in complex matrices through the analysis of UV spectra. We have successfully applied this method to melanoma tumors and cells. Murine B16BL6 tumor are highly pigmented with mostly eumelanin (98.1% of eumelanin) while human SK-MEL-3 tumor contain about 30% pheomelanin. B16BL6 and B16F10 are eumelanic cells lines and NHEM melanocytes contain about 24% of pheomelanin.


Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Melaninas/análise , Melanoma/química , Extração em Fase Sólida/métodos , Animais , Linhagem Celular Tumoral , Humanos , Limite de Detecção , Modelos Lineares , Masculino , Melaninas/química , Melaninas/isolamento & purificação , Camundongos , Reprodutibilidade dos Testes
6.
Nat Commun ; 10(1): 1114, 2019 03 07.
Artigo em Inglês | MEDLINE | ID: mdl-30846699

RESUMO

Advances in genetic engineering have enabled the use of bacterial outer membrane vesicles (OMVs) to deliver vaccines, drugs and immunotherapy agents, as a strategy to circumvent biocompatibility and large-scale production issues associated with synthetic nanomaterials. We investigate bioengineered OMVs for contrast enhancement in optoacoustic (photoacoustic) imaging. We produce OMVs encapsulating biopolymer-melanin (OMVMel) using a bacterial strain expressing a tyrosinase transgene. Our results show that upon near-infrared light irradiation, OMVMel generates strong optoacoustic signals appropriate for imaging applications. In addition, we show that OMVMel builds up intense heat from the absorbed laser energy and mediates photothermal effects both in vitro and in vivo. Using multispectral optoacoustic tomography, we noninvasively monitor the spatio-temporal, tumour-associated OMVMel distribution in vivo. This work points to the use of bioengineered vesicles as potent alternatives to synthetic particles more commonly employed for optoacoustic imaging, with the potential to enable both image enhancement and photothermal applications.


Assuntos
Nanopartículas , Técnicas Fotoacústicas/métodos , Animais , Proteínas da Membrana Bacteriana Externa/química , Bioengenharia , Biopolímeros/química , Feminino , Temperatura Alta/uso terapêutico , Neoplasias Mamárias Experimentais/diagnóstico por imagem , Neoplasias Mamárias Experimentais/terapia , Melaninas/química , Camundongos , Camundongos Nus , Nanopartículas/química , Nanotecnologia , Nanomedicina Teranóstica
7.
Food Funct ; 10(2): 1017-1027, 2019 Feb 20.
Artigo em Inglês | MEDLINE | ID: mdl-30706914

RESUMO

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.


Assuntos
Agaricales/química , Etanol/toxicidade , Hepatopatias Alcoólicas/prevenção & controle , Melaninas/farmacologia , Animais , Regulação da Expressão Gênica/efeitos dos fármacos , Hepatócitos/efeitos dos fármacos , Fígado/efeitos dos fármacos , Fígado/metabolismo , Fígado/patologia , Masculino , Melaninas/química , Camundongos , Camundongos Endogâmicos C57BL
8.
Ecotoxicology ; 28(3): 302-322, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30758729

RESUMO

Heavy metal pollution destruct soil microbial compositions and functions, plant's performance and subsequently human health. Culturable microbes among many metal abatement strategies are considered inexpensive, viable and environmentally safe. In this study, nitrogen fixing bacterial strain CAZ3 recovered from chilli rhizosphere tolerated 100, 1000 and 1200 µg mL-1 of cadmium, chromium and nickel, respectively and was identified as Azotobacter chroococcum by 16S rDNA sequence analysis. Under metal stress, cellular morphology of A. chroococcum observed under SEM was found distorted and shrinkage of cells was noticed when grown with 50 µg mL-1 of Cd (cell size 1.7 µm) and 100 of µg mL-1 Ni (cell size 1.3 µm) compared to untreated control (cell size 1.8 µm). In the presence of 100 µg mL-1 of Cr, cells became elongated and measured 1.9 µm in size. Location of metals inside the cells was revealed by EDX. A dose dependent growth arrest and consequently the death of A. chroococcum cells was revealed under CLSM. A. chroococcum CAZ3 secreted 320, 353 and 133 µg EPS mL-1 when grown with 100 µg mL-1 each of Cd, Cr and Ni, respectively. The EDX revealed the presence of 0.4, 0.07 and 0.24% of Cd, Cr and Ni, respectively within EPS extracted from metal treated cells. Moreover, a dark brown pigment (melanin) secreted by A. chroococcum cells under metal pressure displayed tremendous metal chelating activity. The EDX spectra of melanin extracted from metal treated cells of A. chroococcum CAZ3 displayed 0.53, 0.22 and 0.12% accumulation of Cd, Cr and Ni, respectively. The FT-IR spectra of EPS and melanin demonstrated stretching vibrations and variations in surface functional groups of bacterial cells. The C-H stretching of CH3 in fatty acids and CH2 groups, stretching of N-H bond of proteins and O-H bond of hydroxyl groups caused the shifting of peaks in the EPS spectra. Similar stretching vibrations were recorded in metal treated melanin which involved CHO, alkyl, carboxylate and alkene groups resulting in significant peak shifts. Nuclear magnetic resonance (NMR) spectrum of EPS extracted from A. chroococcum CAZ3 revealed apparent peak signals at 4.717, 9.497, 9.369 and 9.242 ppm. However, 1H NMR peaks were poorly resolved due largely to the impurity/viscosity of the EPS. The entrapment of metals by EPS and melanin was confirmed by EDX. Also, the induction and excretion of variable amounts of metallothioneins (MTs) by A. chroococcum under metal pressure was interesting. Conclusively, the present findings establish- (i) cellular damage due to Cd, Cr and Ni and (ii) role of EPS, melanin and MTs in adsorption/complexation and concurrently the removal of heavy metals. Considering these, A. chroococcum can be promoted as a promising candidate for supplying N efficiently to plants and protecting plants from metal toxicity while growing under metal stressed environment.


Assuntos
Azotobacter/efeitos dos fármacos , Metais Pesados/toxicidade , Polissacarídeos Bacterianos/química , Poluentes do Solo/toxicidade , Azotobacter/química , Cádmio/toxicidade , Cromo/toxicidade , Melaninas/química , Níquel/toxicidade , Plantas/microbiologia , Rizosfera , Solo/química , Espectroscopia de Infravermelho com Transformada de Fourier
9.
Carbohydr Polym ; 207: 391-397, 2019 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-30600021

RESUMO

A carboxylate chitooligomer (C-COS) containing carboxyl groups attached to chitooligomer (COS) molecules has been prepared by laccase/2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) system, which is a green-chemistry method. Several experiments were designed to evaluate inhibition effects on melanin and mechanisms of C-COS. The results indicated that C-COS exhibited more distinct anti-melanogenic effects compared to COS. C-COS inhibits melanin production with tyrosine (Tyr) and DOPA as the substrate of melanin formation, and the inhibition rates are, respectively, 89.07% and 84.45%, which reach 1.4-2 times those of COS. UV-vis spectroscopy was used to elucidate the interaction mechanism between C-COS and tyrosinase (TYR). It is C-COS chelating with metal Cu ions in tyrosinase (TYR) that decreases the enzyme activity. Half-maximal inhibitory concentrations (IC50) of C-COS were calculated as 13.49 and 4.07 mg/mL for monophenolase (cresolase) and diphenolase (catecholase), respectively.


Assuntos
Quitina/análogos & derivados , Melaninas/antagonistas & inibidores , Preparações Clareadoras de Pele/química , Agaricales/enzimologia , Quelantes/síntese química , Quelantes/química , Quitina/síntese química , Quitina/química , Cobre/química , Óxidos N-Cíclicos/química , Inibidores Enzimáticos/síntese química , Inibidores Enzimáticos/química , Química Verde/métodos , Lacase/química , Levodopa/química , Melaninas/química , Modelos Biológicos , Monofenol Mono-Oxigenase/antagonistas & inibidores , Monofenol Mono-Oxigenase/química , Oxirredução , Preparações Clareadoras de Pele/síntese química , Tirosina/química
10.
ACS Appl Mater Interfaces ; 11(8): 7927-7935, 2019 Feb 27.
Artigo em Inglês | MEDLINE | ID: mdl-30688436

RESUMO

Self-detoxifying materials capable of both capture and destruction of chemical warfare agents (CWAs) are highly desirable for efficient personal protection and safe handling of contaminated materials. Developing new strategies to improve CWA removal efficiency of these materials is highly relevant to CWA purification technology. Herein, we present novel photothermally enhanced catalytic detoxification of CWA simulants and its application in self-detoxifying gas filters. The material design features a well-defined core-shell nanostructure (CSN) consisting of an inner photothermal material and an outer microporous catalyst. As a demonstration, the CSN was obtained by growing a Zr-based metal-organic framework (MOF), UiO-66-NH2, onto bioinspired dopamine-melanin (Dpa) nanoparticles via heterogeneous nucleation induced by metal chelation. The resultant Dpa@UiO-66-NH2 CSN has increased the turnover frequency (TOF) of a nerve agent simulant, 4-nitrophenyl phosphate (DMNP), by 2.9- and 1.7-fold in the presence of NIR laser and simulated solar light, respectively. Further incorporation of Dpa@UiO-66-NH2 CSNs into polymer fibers by electrospinning has led to an even greater photothermal enhancement effect (5.8- and 3.2-fold TOF increase), achieving a faster DMNP degradation rate than the corresponding pure MOF powder for the first time and the shortest half-life of DMNP (1.8 min) among reported MOF-based self-detoxifying fabrics. The significant photothermal enhancement in the detoxification ability of Dpa@UiO-66-NH2 fabrics is attributed to the instantaneous heat transfer from the photothermal core to the catalytic shell and effective heat retention enabled by the surrounding polymer matrix. The Dpa@UiO-66-NH2 fabrics can be easily prepared on a large scale and demonstrate efficient protection against DMNP aerosols as stand-alone gas filters. This strategy of photothermally enhanced catalytic detoxification can be feasibly extended to other catalytic detoxification systems and holds promise for next-generation gas masks.


Assuntos
Substâncias para a Guerra Química/química , Melaninas/química , Estruturas Metalorgânicas/química , Catálise , Raios Infravermelhos , Luz , Nanopartículas/química , Porosidade , Temperatura Ambiente , Zircônio/química
11.
J Agric Food Chem ; 67(1): 132-139, 2019 Jan 09.
Artigo em Inglês | MEDLINE | ID: mdl-30541276

RESUMO

Natural melanin features many interesting properties, including the ability to shield electromagnetic radiation, the ability to act as scavenger for radical and reactive oxygen species and the capacity to chelate different metal ions. For these reasons, melanin is becoming increasingly relevant for the development of functional materials with potential applications in cosmetics, drug delivery, and water purification. However, the extraction and purification of melanin from conventional sources (e.g., sepia ink, hair, and wool) is inefficient and not easily scalable, hence diverting its technological applications. Some fungal species, especially wood-decay basidiomycetes, can be regarded as promising sources of melanin. In the present study, we screened different fungi in regard to their melanin-biosynthesis abilities using l-tyrosine as a precursor, and we found that an Armillaria cepistipes strain (Empa 655) produced the highest yield of melanin (27.98 g L-1). Physicochemical characterization of the obtained fungal melanin revealed a typical eumelanin structure. The method for the biosynthesis of fungal melanin we propose is efficient, scalable, and sustainable and has the potential to provide support for further technological exploitation.


Assuntos
Armillaria/metabolismo , Melaninas/biossíntese , Armillaria/química , Armillaria/genética , Armillaria/crescimento & desenvolvimento , Meios de Cultura/metabolismo , Fermentação , Melaninas/química , Melaninas/isolamento & purificação , Tirosina/metabolismo
12.
Appl Biochem Biotechnol ; 188(2): 555-567, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30547280

RESUMO

The purpose of this study was to examine the protective effects of intracellular homogeneous melanin produced by Lachnum YM156 (LIM) against ultraviolet B (UVB) induced damage in mice. The possible structural formula of the LIM was concluded based on elemental analysis, ultraviolet-visible spectroscopy (UV-Vis), Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), and mass spectrometry (MS). The LIM was modified by arginine to improve its water solubility and biological activities. LIM and ALIM show significant anti-radiation activity in which LIM and ALIM protect the skin under UV radiation. Results indicate that activities of anti-oxidant enzymes in skin were improved after treatment of LIM or ALIM. In addition, LIM and ALIM inhibited over expression of the pro-inflammatory cytokines, including interleukin (IL)-1α, IL-1ß, and IL-6 and tumor necrosis factor-α (TNF-α). The protection ability of ALIM was higher than that of LIM at the same dose. Thus, applied LIM and ALIM may be a promising radiation-protective agent.


Assuntos
Ascomicetos/metabolismo , Melaninas/química , Melaninas/farmacologia , Protetores contra Radiação/química , Protetores contra Radiação/farmacologia , Pele/lesões , Raios Ultravioleta/efeitos adversos , Animais , Antioxidantes/química , Antioxidantes/isolamento & purificação , Antioxidantes/farmacologia , Biotecnologia , Citocinas/metabolismo , Modelos Animais de Doenças , Masculino , Melaninas/isolamento & purificação , Camundongos , Estrutura Molecular , Espectroscopia de Prótons por Ressonância Magnética , Protetores contra Radiação/isolamento & purificação , Pele/efeitos dos fármacos , Pele/efeitos da radiação , Solubilidade , Espectroscopia de Infravermelho com Transformada de Fourier , Queimadura Solar/tratamento farmacológico , Queimadura Solar/imunologia , Queimadura Solar/metabolismo
13.
Int J Biol Macromol ; 126: 755-764, 2019 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-30572055

RESUMO

Rubrivivax benzoatilyticus JA2 is a metabolically versatile bacterium, thrives on a wide array of organic compounds under different growth modes. Though genomic insights revealed the aromatic compound catabolic potential of strain JA2 under anaerobic/aerobic conditions, the studies are largely restricted to anaerobic metabolism. The previous study on phenylalanine metabolism in strain JA2 indicated melanin-like pigment production under aerobic conditions; however, characterization of pigment and its biosynthetic pathway is not explored. The current study aims at the characterization of pigment and elucidation of its biosynthetic pathway. Strain JA2 utilized l-phenylalanine as source of nitrogen under anaerobic/aerobic conditions but not as a carbon source. Strain JA2 produced a brown-pigment under phenylalanine-amended aerobic conditions. Spectroscopic and physicochemical analysis identified the purified brown-pigment as a melanin. Further, the genomic insights revealed the presence of a complete set of genes related to pyomelanin synthesis. Identification of key metabolites l-tyrosine, 4-hydroxyphenylpyruvic acid and homogentisic acid and their respective enzyme activities further supports the pyomelanin synthesis. Moreover, the precursors feeding, pathway specific inhibitor studies confirmed the pyomelanin synthesis in strain JA2. Our study revealed an incomplete catabolism of phenylalanine; absence of ring cleavage gene, homogentisate dioxygenase leading to homogentisate accumulation thereby pyomelanin synthesis in strain JA2.


Assuntos
Betaproteobacteria/metabolismo , Melaninas/biossíntese , Fenilalanina/metabolismo , Fotossíntese , Aerobiose , Betaproteobacteria/crescimento & desenvolvimento , Cicloexanonas/química , Cicloexanonas/metabolismo , Genoma Bacteriano , Melaninas/química , Mesilatos/química , Mesilatos/metabolismo , Filogenia , Tirosina/metabolismo , Difração de Raios X
14.
J Photochem Photobiol B ; 186: 207-215, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-30075426

RESUMO

Pseudocercospora griseola is the causal agent of Angular Leaf Spot (ALS), a disease of common bean. Due to its coevolution with beans, two major groups have been defined, "Andean" (P. griseola f. griseola) and "Mesoamerican" (P. griseola f. mesoamericana). The aim of this study was to characterize the dark pigment, melanin, synthetized by a selected isolate of each genic group of P. griseola when grown on Potato-dextrose broth. P. griseola f. griseola isolate S3b and P. griseola f. mesoamericana isolate T4 produced 1.7 ±â€¯0.6 and 4.1 ±â€¯0.9 mg of melanin per g of dry biomass, respectively. Although both melanins possessed similar UV-visible absorption spectroscopic pattern, P. griseola f. mesoamericana isolate T4 melanin had a lower UV-visible absorption, higher reducing activity and metal chelating ability than melanin from P. griseola f. griseola isolate S3b. However, when the size of the sample was 10 mg S3b melanin had a higher content of free phenolic groups. Furthermore, cell wall polysaccharides modified in melanin the availability of active phenolic groups, which was dependent on the fungal isolate and the size of the sample. Therefore, the amount and chemical features of melanin as well as its deposition in mycelium walls within isolates is different, which might explain the different pigmentation and physiological behaviours of these representatives of the two groups of P. griseola.


Assuntos
Ascomicetos/metabolismo , Melaninas/química , Antioxidantes/química , Ascomicetos/crescimento & desenvolvimento , Ascomicetos/isolamento & purificação , Biomassa , Espectroscopia de Ressonância de Spin Eletrônica , Melaninas/metabolismo , Oxirredução , Phaseolus/microbiologia , Doenças das Plantas/microbiologia , Espectrofotometria Ultravioleta , Espectroscopia de Infravermelho com Transformada de Fourier
15.
Int J Mol Sci ; 19(8)2018 Aug 07.
Artigo em Inglês | MEDLINE | ID: mdl-30087240

RESUMO

Harnessing melanins to scavenge free radicals in vivo may yield treatment methods for inflammatory disorders. Furthermore, elucidation of the mechanism underlying melanin-mediated suppression of free radicals, which is yet unclear, is warranted. Herein, we chemically synthesized melanin-mimetic nanoparticles (MeNPs) and investigated the mechanism underlying their use. MeNPs efficiently suppressed hydroxyl radicals by converting some MeNP hydroxyl groups to ketone groups. Furthermore, they suppressed hydroxyl radicals produced by lipopolysaccharide-treated Kupffer cells involved in hepatic cirrhosis pathogenesis, without causing significant cytotoxicity. The present results indicate the suitability of MeNPs to treat hepatic cirrhosis; however, further in vivo studies are warranted to determine their treatment efficacy.


Assuntos
Materiais Biomiméticos/farmacologia , Depuradores de Radicais Livres/farmacologia , Radical Hidroxila/antagonistas & inibidores , Macrófagos do Fígado/efeitos dos fármacos , Melaninas/farmacologia , Nanopartículas/química , Materiais Biomiméticos/química , Linhagem Celular , Depuradores de Radicais Livres/química , Humanos , Melaninas/química
16.
Int J Nanomedicine ; 13: 4333-4344, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30087564

RESUMO

Background: Effective endosomal escape is still a critical bottleneck for intracellular delivery of small interfering RNAs (siRNAs) to maximize their therapeutic efficacy. To overcome this obstacle, we have developed a photothermally triggered system by using the near-infrared (NIR) irradiation to achieve "on-demand" endosomal escape and subsequent siRNA release into cytoplasm. Materials and methods: Herein, the poly-L-lysine (PLL) was successfully conjugated with melanin to obtain melanin-poly-L-lysine (M-PLL) polymer as a siRNA vehicle. The melanin was an efficient photothermal sensitizer, and the positive pendant amino groups of PLL could condense siRNAs to form stable complexes by electrostatic interactions. Results and discussion: Inspired by its excellent photothermal conversion efficiency, the melanin was first involved in the siRNA delivery system. Confocal laser scanning microscopic observation revealed that after cellular uptake the photothermally induced endosomal escape could facilitate siRNAs to overcome endosomal barrier and be delivered into cytoplasm, which resulted in significant silence in the luciferase expression over the NIR- and melanin-free controls. Moreover, the anti-survivin siRNA-loaded M-PLL nanoparticles displayed great inhibitory effect on 4T1 tumor growth in vitro and in vivo. Conclusion: These findings suggest that the M-PLL-mediated siRNA delivery is a promising candidate for therapeutic siRNA delivery and shows improved effect for cancer therapy via enhanced endosomal escape.


Assuntos
Antineoplásicos/farmacologia , Endossomos/metabolismo , Técnicas de Transferência de Genes , Luz , RNA Interferente Pequeno/administração & dosagem , Temperatura Ambiente , Animais , Apoptose/efeitos dos fármacos , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Regulação para Baixo/efeitos dos fármacos , Endossomos/efeitos dos fármacos , Feminino , Expressão Gênica , Inativação Gênica/efeitos dos fármacos , Humanos , Proteínas Inibidoras de Apoptose/metabolismo , Luciferases/metabolismo , Melaninas/química , Camundongos Endogâmicos BALB C , Nanopartículas/administração & dosagem , Nanopartículas/ultraestrutura , Metástase Neoplásica , Polilisina/química , RNA Interferente Pequeno/genética , Proteínas Repressoras/metabolismo , Survivina
17.
Anal Sci ; 34(7): 837-840, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29998967

RESUMO

We investigated melanin radicals in paraffin-embedded malignant melanoma (MM) using a surface-type dielectric resonator for X-band electron paramagnetic resonance (EPR) and analyzed the radical species. The surface-type resonator's performance was examined using 5 - 10 µL of 0.1 mM 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPOL) aqueous solution in a 1.0-mm (i.d.) glass capillary as well as 1,1-diphenyl-2-picrylhydrazyl (DPPH) powder. The surface-type detection has approximately two times poorer S/N ratio than commercial insertion-type detection. A sample of the paraffin-embedded MM specimen was used for the radical detection. We obtained an EPR spectrum of melanin radicals in the paraffin-embedded melanoma sample (size ∼3 × 4 × 3 mm). A single line (∼0.64 mT peak-to-peak line-width) with a small shoulder was observed and was identified as a pheomelanin-related radical. The pheomelanin radical can be directly related to the MM. Thus, the present results were a good indication for noninvasive measurement, as well as for detailed analyses of melanin radicals in human MM.


Assuntos
Espectroscopia Dielétrica , Espectroscopia de Ressonância de Spin Eletrônica , Melaninas/química , Melanoma/química , Idoso , Feminino , Radicais Livres/química , Humanos , Masculino , Pessoa de Meia-Idade , Inclusão em Parafina , Propriedades de Superfície
18.
Int J Mol Sci ; 19(6)2018 Jun 13.
Artigo em Inglês | MEDLINE | ID: mdl-29899264

RESUMO

In the last decade, the late stages of melanin biosynthesis involving the oxidative polymerization of 5,6-dihydroxyindole (DHI) and 5,6-dihydroxyindole-2-carboxylic acid (DHICA) have been extensively investigated. Most of the information derived from a biomimetic approach in which the oxidation of melanogenic indoles was carried out under conditions mimicking those occurring in the biological environment. Characterization of the early oligomers allowed for drawing a structural picture of DHI and DHICA melanins, providing also an interpretative basis for the different properties exhibited by these pigments, e.g., the chromophore and the antioxidant ability. The improved knowledge has opened new perspectives toward the exploitation of the unique chemistry of melanins and its precursors in cosmetic and health care applications. A noticeable example is the development of an innovative hair dyeing system that is based on the marked ease of DHI to give rise to black melanin on air oxidation under slightly alkaline conditions. The advantage of this method for a step-wise coverage of gray hair with a natural shade pigmentation on repeated treatment with a DHI-based formulation with respect to traditional dyes is presented. A variant of DHICA melanin combining solubility in water-miscible organic solvents, an intense chromophore in the UltraViolet-A UV-A region, and a marked antioxidant potency was evaluated as an ingredient for cosmetic formulations.


Assuntos
Tinturas para Cabelo/química , Melaninas/biossíntese , Melanócitos/efeitos dos fármacos , Animais , Tinturas para Cabelo/farmacologia , Tinturas para Cabelo/normas , Humanos , Melaninas/química , Melanócitos/metabolismo , Oxirredução
19.
J Photochem Photobiol B ; 185: 169-175, 2018 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-29936410

RESUMO

Ultraviolet (UV) light is absorbed by nucleic acids, proteins or other endogenous chromophores, such as porphyrins, flavins and melanin, triggering biological processes in skin cells. Both UV-induced mutations in melanocytes and changes in the immune microenvironment are understood to play a role in the development of cutaneous melanoma. The degree of UV-induced stress and the protection against this stress are influenced by both intracellular and intercellular molecular interactions. The present review summarizes the known major molecular biological changes induced by UV light in the skin that play a role in melanoma initiation and promotion. Nevertheless, cutaneous melanoma is not a homogenous disease, and the interaction of variable environmental exposure and different genetic susceptibility and other host factors lead to the formation of melanomas with different biological behavior and clinical characteristics. This review highlights the challenges in the understanding of how UV radiation contributes to the formation of cutaneous melanoma, and reviews the new results of photobiology and their link to tumor genetics and tumor immunology with potential implications on melanoma prevention and therapeutic strategies. The information presented here is expected to add clarity to ongoing research efforts in this field to aid the development of novel strategies to prevent and treat melanoma.


Assuntos
Melanoma/etiologia , Neoplasias Cutâneas/etiologia , Pele/efeitos da radiação , Raios Ultravioleta , Animais , Colecalciferol/química , Colecalciferol/metabolismo , Dano ao DNA/efeitos da radiação , Humanos , Melaninas/química , Melaninas/metabolismo , Melanoma/imunologia , Melanoma/metabolismo , Espécies Reativas de Oxigênio/química , Espécies Reativas de Oxigênio/metabolismo , Pele/metabolismo , Neoplasias Cutâneas/imunologia , Neoplasias Cutâneas/metabolismo
20.
Eur J Med Chem ; 152: 274-282, 2018 May 25.
Artigo em Inglês | MEDLINE | ID: mdl-29730190

RESUMO

Naturally occurring coumarins 7-isopentenyloxycoumarin, auraptene, and umbelliprenin are able to modulate the biosynthesis of melanin in murine Melan-a cells probably through the interaction with selected biological targets like estrogen receptor ß and aryl hydrocarbon receptor. Such a modulation strictly depends on the individual structure of the coumarin: the presence of a 3,3-dimethylallyloxy side chain is a structural determinant for tanning activation whereas a farnesyl one leads to the opposite effect. The parent compound with a free OH group, umbelliferone, did not provide any interaction. Other coumarins assayed, having shorter chains and/or being substituted in other positions, and prenyloxypsoralens, were not active or not further investigated in this context being cytotoxic at low doses.


Assuntos
Produtos Biológicos/farmacologia , Cumarínicos/farmacologia , Melaninas/biossíntese , Animais , Produtos Biológicos/síntese química , Produtos Biológicos/química , Proliferação de Células , Sobrevivência Celular , Células Cultivadas , Cumarínicos/síntese química , Cumarínicos/química , Relação Dose-Resposta a Droga , Melaninas/análise , Melaninas/química , Melanócitos/efeitos dos fármacos , Melanócitos/metabolismo , Camundongos , Estrutura Molecular , Relação Estrutura-Atividade
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA