Generation and suppression of singlet oxygen in hair by photosensitization of melanin

Chiarelli-Neto, Orlando; Pavani, Christiane; Ferreira, Alan S.; Fernandes, Adjaci Uchôa; Severino, Divinomar; Baptista, Maurı́cio S.

doi:10.1016/j.freeradbiomed.2011.06.013

Cited by 60 publications

(81 citation statements)

References 39 publications

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“…The bandwidth probably is due to the polymeric nature and dynamics of formation and inactivation of O 2 ( 1 Δ g ) within the same structure of photosensitized melanin. The O 2 ( 1 Δ g ) spectra of the melanin standard (Figure 5B) have the same emission pattern in the NIR region as fungal melanin, and the monomol light emission spectrum of O 2 ( 1 Δ g ) shown is consistent with reported spectra from the photosensitized hair eumelanin [6].…”

Section: Resultssupporting

confidence: 77%

“…For microorganisms, melanin participates in energy transduction and electron transfer processes [3], [4]. On the other hand eumelanin was found to act as a photosensitizers under UV radiation, thereby generating reactive oxygen species (ROS) such as hydrogen peroxide (H 2 O 2 ), hydroxyl radical (OH) [5] and singlet molecular oxygen [O 2 ( 1 Δ g )] [6], with some studies implicating melanin photochemistry with the production of DNA strand breaks [7]. However melanin also acts as a scavenger of a variety of oxidizing and reducing radicals [8].…”

Section: Introductionmentioning

confidence: 99%

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Singlet Molecular Oxygen Generation by Light-Activated DHN-Melanin of the Fungal Pathogen Mycosphaerella fijiensis in Black Sigatoka Disease of Bananas

et al. 2014

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In pathogenic fungi, melanin contributes to virulence, allowing tissue invasion and inactivation of the plant defence system, but has never been implicated as a factor for host cell death, or as a light-activated phytotoxin. Our research shows that melanin synthesized by the fungal banana pathogen Mycosphaerella fijiensis acts as a virulence factor through the photogeneration of singlet molecular oxygen O2 (1Δg). Using analytical tools, including elemental analysis, ultraviolet/infrared absorption spectrophometry and MALDI-TOF mass spectrometry analysis, we characterized both pigment content in mycelia and secreted to the culture media as 1,8-dihydroxynaphthalene (DHN)-melanin type compound. This is sole melanin-type in M. fijiensis. Isolated melanins irradiated with a Nd:YAG laser at 532 nm produced monomol light emission at 1270 nm, confirming generation of O2 (1Δg), a highly reactive oxygen specie (ROS) that causes cellular death by reacting with all cellular macromolecules. Intermediary polyketides accumulated in culture media by using tricyclazole and pyroquilon (two inhibitors of DHN-melanin synthesis) were identified by ESI-HPLC-MS/MS. Additionally, irradiation at 532 nm of that mixture of compounds and whole melanized mycelium also generated O2 (1Δg). A pigmented-strain generated more O2 (1Δg) than a strain with low melanin content. Banana leaves of cultivar Cavendish, naturally infected with different stages of black Sigatoka disease, were collected from field. Direct staining of the naturally infected leaf tissues showed the presence of melanin that was positively correlated to the disease stage. We also found hydrogen peroxide (H2O2) but we cannot distinguish the source. Our results suggest that O2 (1Δg) photogenerated by DHN-melanin may be involved in the destructive effects of Mycosphaerella fijiensis on banana leaf tissues. Further studies are needed to fully evaluate contributions of melanin-mediated ROS to microbial pathogenesis.

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Section: Resultssupporting

confidence: 77%

Section: Introductionmentioning

confidence: 99%

Singlet Molecular Oxygen Generation by Light-Activated DHN-Melanin of the Fungal Pathogen Mycosphaerella fijiensis in Black Sigatoka Disease of Bananas

et al. 2014

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“…In recent studies, Chiarelli-Neto et al (2011) found that singlet oxygen induced hair damage was produced by photosensitization of melanin. However, Brenner &Hearing (2009) andGeng et al (2008) reported that melanin was the most important photoprotective factor and had antioxidant and radical scavenging properties.…”

Section: Hydroxyl Radical Scavenging Activity Of Aafb Melaninmentioning

confidence: 99%

Chemical composition and radical scavenging activity of melanin from Auricularia auricula fruiting bodies

Zou¹,

Zhao²,

Hu³

2015

Food Sci. Technol (Campinas)

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Melanin extracted from Auricularia auricula fruiting bodies (AAFB) was examined by element analyzer, amino acid analyzer, inductively coupled plasma-optical emission spectrometry. Elemental composition analysis revealed that main component of AAFB melanin was pheomelanin. Amino acid analysis showed that 16 amino acids were found in AAFB melanin and total amino acid content was 321. 63 mg/g. There were 13 detectable metal elements in AAFB melanin, which was rich in Ca, Fe, Cu and Zn. In addition, AAFB melanin exhibited stronger scavenging activities on 2,2-diphenyl-l-picrylhydrazyl (DPPH) radical, superoxide radical and hydroxyl radical with IC 50 values of 0.18, 0.59 and 0.34 mg/mL, respectively. These results indicated that AAFB melanin might be potentially used as a natural antioxidant.

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“…These physicochemical properties include strong light absorbance, unusual solubility, and remarkable redox properties. In addition, melanin has a number of healthful functions, such as antioxidant 6,7 and anti-HIV activity 8,9 . As a result, consumers are demanding to use melanin in the food industry as a safe natural colourant rather than a synthetic dye.…”

Section: Introductionmentioning

confidence: 99%

Properties of melanin from black tea leaves

Zhao¹

2015

ScienceAsia

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ABSTRACT:In this study, partial physicochemical properties and antioxidant activities of melanin from black tea leaves were studied. The results show that black tea melanin powder was dark tinted red and yellow (L * = 36.47, a * = 0.33,Black tea melanin solution exhibited strong optical absorbance in a wide UV-Vis spectral range and was relatively stable in the range of 25-100°C and under natural light. Furthermore, black tea melanin exhibited a strong superoxide-and hydroxyl-radical scavenging activity. Results of the present study indicated that black tea melanin could be potentially used as a food colourant with health benefits.

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Generation and suppression of singlet oxygen in hair by photosensitization of melanin

Cited by 60 publications

References 39 publications

Singlet Molecular Oxygen Generation by Light-Activated DHN-Melanin of the Fungal Pathogen Mycosphaerella fijiensis in Black Sigatoka Disease of Bananas

Singlet Molecular Oxygen Generation by Light-Activated DHN-Melanin of the Fungal Pathogen Mycosphaerella fijiensis in Black Sigatoka Disease of Bananas

Chemical composition and radical scavenging activity of melanin from Auricularia auricula fruiting bodies

Properties of melanin from black tea leaves

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