ELECTRON SPIN RESONANCE OF MELANIN FROM HAIR. EFFECTS OF TEMPERATURE, pH AND LIGHT IRRADIATION

Arnaud, René; Perbet, Gilles; Deflandre, André; Lang, Gérard

doi:10.1111/j.1751-1097.1983.tb03857.x

Cited by 27 publications

(21 citation statements)

References 16 publications

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“…The decrease in intrinsic free radical concentration in hydrated hair and then an increase upon exposure to light seem t o reflect the involvement of water in the melanin complex. Our results agree with the model proposed by Arnaud et al (1983), who explained the participation of water in melanin free radicals in solid melanins, as well as in KBr dispersion. Water molecules preferentially solvate hydrogen-bonded acceptor or donor sites, which will decrease in concentration of radicals in the presence of water.…”

Section: Resultssupporting

confidence: 92%

Effect of Humidity on Photoinduced Esr Signal From Human Hair

Jahan

Drouin

Sayre

1987

Photochem & Photobiology

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Abstract— Human red hairs, equilibrated at 79.8%, 58.0%, 32.3% humidity and at dry conditions, were irradiated with UV‐visible (Λ > 290 nm) light. ESR intensity of the photo‐induced transient free radicals was measured, at room temperature, as a function of time during and after exposure to light. Photoenhancement was found to be most pronounced in 79.8%‐humidity conditioned hair and least in dry hair. The lifetimes of the transient free radicals in these samples were measured as 360s (79.8%), 180s (58.0%), 140s (32.3%), and 50s (dry). The gradual increase in lifetime as a function of humidity conditions was attributed to an increasing number of decay rates of the centers varying from fast to slow, the slow ones being unable to decay unless the fast ones do. This process is best described by a stretched exponential time function, I(t) =Ioexp[‐(t/to)α].

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Section: Resultssupporting

confidence: 92%

Effect of Humidity on Photoinduced Esr Signal From Human Hair

Jahan

Drouin

Sayre

1987

Photochem & Photobiology

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“…This could explain why somewhat narrower 13 C resonances were obtained in the case of Human hair melanin in comparison with the Sepia melanin. Literature ESR data on melanin obtained from Japanese black hair 21 also shows a single absorption line; however, the free radical concentration differed and was found to be 3.6 ð 10 18 free radicals g 1 . The difference in free radical content can be attributed to several factors, such as water content (known to reduce the ESR signal) and pH (increased acidity reduces the signal, whereas increased basicity increases the ESR signal).…”

Section: Human Hair Melaninmentioning

confidence: 84%

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

Adhyaru

Akhmedov

Katritzky

et al. 2003

Magnetic Reson in Chemistry

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“…It is confirmed that melanin plays the most important protective role against UV radiation in the skin …”

Section: Introductionmentioning

confidence: 83%

Electron spin resonance (ESR/EPR) of free radicals observed in human red hair: a new, simple empirical method of determination of pheomelanin/eumelanin ratio in hair

Chikvaidze

Partskhaladze

Gogoladze

2014

Magnetic Reson in Chemistry

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The definition of the concentration of pheomelanin in the skin is an issue of great interest because in the case of being influenced by UV radiation, it manifests itself as a prooxidant, causing various skin disorders including melanoma that might help to explain the relatively high incidence of skin cancer among individuals with red hair. The ESR spectra of red hair samples were investigated. It was found that at low microwave power, they are characterized by two types of spectra. Red hair ESR signals result from a superposition of two spectral shapes, a singlet spectrum as a result of the existence of eumelanin and a triplet spectrum as a result of the existence of pheomelanin. At high microwave power, only triplet spectra shape was detected, caused by saturation of the eumelanin singlet. Using different concentration ratios of black to red hair, we measured ESR spectra and plotted the ratio values in each sample against a measured 'g-factor' (experimental). We found that there is a linear relationship between these two parameters. So, it is evident that using these results, the concentration ratio of pheomelanin to eumelanin in a sample of hair can be easily determined by an almost noninvasive method. This can be considered a potential advantage for many practical activities compared with other invasive methods. The concentration dependence curve of pheomelanin (µg/mg) on gexp-factor in an ESR spectrum of hair has been designed, which allows the determination of the amount of pheomelanin in hair of any color.

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ELECTRON SPIN RESONANCE OF MELANIN FROM HAIR. EFFECTS OF TEMPERATURE, pH AND LIGHT IRRADIATION

Cited by 27 publications

References 16 publications

Effect of Humidity on Photoinduced Esr Signal From Human Hair

Effect of Humidity on Photoinduced Esr Signal From Human Hair

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

Electron spin resonance (ESR/EPR) of free radicals observed in human red hair: a new, simple empirical method of determination of pheomelanin/eumelanin ratio in hair

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ELECTRON SPIN RESONANCE OF MELANIN FROM HAIR. EFFECTS OF TEMPERATURE, pH AND LIGHT IRRADIATION

Cited by 27 publications

References 16 publications

Effect of Humidity on Photoinduced Esr Signal From Human Hair

Effect of Humidity on Photoinduced Esr Signal From Human Hair

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

Electron spin resonance (ESR/EPR) of free radicals observed in human red hair: a new, simple empirical method of determination of pheomelanin/eumelanin ratio in hair

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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