Effect of humidity on photoinduced radicals in human hair

Groves, Philip; Marsh, Jennifer; Sun, Yiping; Chaudhary, Tanuja; Chechik, Victor

doi:10.1016/j.freeradbiomed.2018.04.548

Cited by 11 publications

(12 citation statements)

References 22 publications

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“…The paper by Groves et al looking at the effect of increased RH on the EPR spectrum of white hair supports this hypothesis. At maximum humidity (100% RH), the EPR peak due to sulphur radicals is much higher than in dry hair, which supports the idea that reaction of Tyr radicals with Cys increases in the presence of water because of increased molecular mobility and O 2 availability within the fibre.…”

Section: Resultsmentioning

confidence: 88%

“…Previous work showed that NAC can react with Tyr phenoxy radicals , which are believed to be the free radicals responsible for the intrinsic EPR spectrum of wool and white hair . We subsequently ran an EPR spectrum of NAC‐treated white hair before UV exposure, which showed that the weak feature shown in Fig.…”

Section: Resultsmentioning

confidence: 91%

“…The signal originates from both carbon and sulphur free radicals formed in the keratin proteins [13,14]. Several EPR studies on UV-treated unpigmented hair have also been carried out with similar results [9,[15][16][17].…”

Section: Introductionmentioning

confidence: 88%

“…In future studies, photoyellowing tests on treated white hair will need to be carried out over long periods using simulated sunlight. Use of high relative humidity conditions would also be appropriate, since this has been shown to result in higher levels of fibre damage [15]. Values are the mean of three measurements in different areas of the sample tress.…”

Section: Colour Changes and Photoyellowingmentioning

confidence: 99%

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UV damage to hair and the effect of antioxidants and metal chelators

Millington

Marsh

2020

Intern J of Cosmetic Sci

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Objective To study the effects of addition of a redox metal, copper, antioxidants and metal chelators on the formation of free radicals in natural white Caucasian hair subsequently exposed to UV light. Three different methods, electron paramagnetic resonance (EPR), a fluorescent probe for hydroxyl radical formation (terephthalate) and free radical photoyellowing, were used. These methods utilized different UV sources and reaction conditions, and so can give insights into the different mechanisms of action occurring during UV oxidation of hair. In addition, this study demonstrates how antioxidants and chelators can be screened to determine whether they can protect hair from UV damage. Results The three methods gave somewhat different results, illustrating the importance of reaction conditions and wavelength on the photochemical mechanisms, and the efficacy of additives to influence these reactions. EPR results showed that N‐acetylcysteine (NAC) pre‐treatment eliminated the intensity of the signal because of sulphur and carbon free radicals in white hair both before and after exposure to UVB radiation. Doping the hair with copper ions had no effect on the intensity of the EPR signal under dry conditions. Terephthalate fluorescent probe data showed that under wet conditions, irradiation of white hair with UVA produced significant amounts of hydroxyl radicals. Pre‐treatment of hair with NAC reduced the number of •OH radicals produced by natural white hair compared to an untreated control. In contrast to the EPR result, white hair doped with copper ions produced significantly higher levels of •OH radicals under wet conditions. It appears that the ability of copper ions to catalyse the photogeneration free radicals in hair is highly dependent on water content. Photoyellowing data showed a benefit for oxalic acid but no difference for NAC and an increase in yellowing for EDTA. Conclusion The micro‐EPR and terephthalate fluorescent probe methods are both effective techniques to study production of free radicals by hair exposed to UV light under wet and dry conditions, respectively. Both assays are simple methods for determining the effectiveness of potential protective hair treatments against UV damage, but because they assess free radical damage under dry vs wet conditions, the chemistry created on UV exposure is different. This gives insights into mechanism of action, but results may not be consistent between the two methods for actives added for reduction of UV damage. NAC pre‐treatment did reduce free radical generation in UV‐exposed hair under both wet and dry conditions. Photoyellowing data are more complicated as it is a less direct measure of UV damage and is highly dependent on irradiation source. Using UVB irradiation is experimentally convenient but may not be appropriate, because UVB wavelengths comprise only 0.3% of terrestrial sunlight. The photochemistry of hair exposed to sunlight involves concurrent photobleaching and photoyellowing processes and is far more complex. Under UVB irradiation condit...

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Section: Resultsmentioning

confidence: 88%

Section: Resultsmentioning

confidence: 91%

Section: Introductionmentioning

confidence: 88%

Section: Colour Changes and Photoyellowingmentioning

confidence: 99%

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UV damage to hair and the effect of antioxidants and metal chelators

Millington

Marsh

2020

Intern J of Cosmetic Sci

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“…46 EPR spectroscopy was also used in studies of melanin biopolymers from Substantia nigra, skin, eyes, and hair. [47][48][49][50] o-Semiquinone free radicals were identified by us earlier in normal human melanocytes, A-2058 tumor cells, and in melanin isolated from A-375 and G-361 human melanoma malignum cells. [11][12][13][14] The free radical concentrations in the all A-2058 cells cultured with SIM were lower than in the control cells.…”

mentioning

confidence: 92%

Effect of simvastatin in different concentrations on free radicals in A‐2058 human melanoma malignum cells—EPR studies

Zdybel

Chodurek

Pilawa

2018

J of Cellular Biochemistry

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The influence of concentration of simvastatin (SIM) on free radicals in A‐2058 human melanoma malignum cells was studied. The proliferation assay for melanoma A‐2058 cells with SIM in concentration range from 0.1 to 20 µM was performed. SIM in the concentrations of 0.1, 0.3, and 1 μM only slightly changed the growth of A‐2058 cells, but the growth of the cells considerably decreased for higher concentrations of SIM. Free radicals in the cells were examined by an X‐band (9.3 GHz) electron paramagnetic resonance (EPR) spectroscopy. o‐Semiquinone free radicals with g‐factors in the range of 2.0060 to 2.0065 were found in A‐2058 cells. The asymmetric broad EPR spectra with linewidths (ΔBpp) from 0.87 to 1.25 mT were measured. The fast spin‐lattice relaxation processes characterized all the tested cells. The free radical concentrations in the all A‐2058 cells cultured with SIM were lower than in the control cells. The quenching of free radicals in A‐2058 cells depended on concentration of SIM. This effect was the weakest for concentration of SIM of 3 μM. The strongest decrease of free radical concentration caused SIM in concentration of 1 μM.

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UV DEGRADATION & STABILIZATION OF INDUSTRIAL PRODUCTS

2020

Handbook of UV Degradation and Stabilization

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Effect of humidity on photoinduced radicals in human hair

Cited by 11 publications

References 22 publications

UV damage to hair and the effect of antioxidants and metal chelators

UV damage to hair and the effect of antioxidants and metal chelators

Effect of simvastatin in different concentrations on free radicals in A‐2058 human melanoma malignum cells—EPR studies

UV DEGRADATION & STABILIZATION OF INDUSTRIAL PRODUCTS

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