EPR examination of Zn2+ and Cu2+ effect on free radicals in DOPA–melanin–netilmicin complexes

Buszman, Ewa; Pilawa, Barbara; Zdybel, Magdalena; Wrześniok, Dorota; Grzegorczyk, Aneta; Wilczok, Tadeusz

doi:10.1016/j.cplett.2004.12.069

Cited by 30 publications

(46 citation statements)

References 30 publications

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“…These values are in the range obtained earlier for melanins with o-semiquinone free radicals [1,3,[11][12][13][17][18][19]. However g factor for broad EPR lines with unresolved hyperfi ne structure does not directly determine the type of free radicals in the samples.…”

Section: Resultssupporting

confidence: 62%

“…3-6), according to the theoretical base [26,27]. Homogeneously broadened EPR lines for nonirradiated melanins were observed earlier [7,[11][12][13][17][18][19][20][21][22].…”

Section: Resultsmentioning

confidence: 99%

“…The linewidths changed after the UVA irradiation of DOPA-melanin-moxifl oxacin complexes [19]. Linewidths of melanin polymers changed after drug binding to melanin [16][17][18][19][20][21] and metal ions [11][12][13][14][15].…”

Section: Resultsmentioning

confidence: 99%

“…Electron paramagnetic resonance (EPR) investigations confi rmed the existence of free radicals in melanins [1][2][3][4][5][6][7][8][9][10], and melanin complexes with metal ions [1,7,[11][12][13][14][15] and drugs [7,12,[16][17][18][19][20][21]. Dia-and paramagnetic metal ions [11][12][13][14][15] and pharmacological substances [16][17][18][19][20][21] change the intensity of EPR lines of melanin.…”

Section: Introductionmentioning

confidence: 99%

“…Dia-and paramagnetic metal ions [11][12][13][14][15] and pharmacological substances [16][17][18][19][20][21] change the intensity of EPR lines of melanin. In this study, we concentrate on free radicals in melanins exposed to UV irradiation.…”

Section: Introductionmentioning

confidence: 99%

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Effect of UV irradiation on free radicals in synthetic melanin and melanin biopolymer from Sepia officinalis – EPR examination

Zdybel

Pilawa

2015

Nukleonika

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Abstract. Free radicals in synthetic melanin and melanin from Sepia offi cinalis were studied by electron paramagnetic resonance (EPR) spectroscopy. The effect of time of ultraviolet (UV) irradiation on free radicals in these melanins was tested. The samples were exposed to UV during 15, 30, and 60 minutes. EPR spectra were measured with microwaves from an X-band (9.3 GHz) in the range of microwave power of 2.2-70 mW. The performed EPR examinations indicate that high concentrations (~10 21 -10 22 spin/g) of o-semiquinone free radicals with g factors of 2.0039-2.0045 exist in all the tested samples. For nonirradiated samples, free radical concentration was higher in natural melanin than in synthetic melanin. UV irradiation caused the increase of free radical concentrations in synthetic melanin samples and this effect depends on the time of irradiation. The largest free radical formation in the both melanins was obtained for 60 min of UV irradiation. Free radical concentrations after the UV irradiation of melanins during 30 min were lower than during irradiation by 15 min, and probably this effect was the result of recombination of the radiatively formed free radicals. EPR lines of the tested samples broadened with increasing microwave power, so these lines were homogeneously broadened. The two types of melanins differed in the time of spin-lattice relaxation processes. Slower spin-lattice relaxation processes exist in melanin from Sepia offi cinalis than in synthetic melanin. UV irradiation did not change the time of spin-lattice relaxation processes in the tested melanins. The performed studies confi rmed the usefulness of EPR spectroscopy in cosmetology and medicine.

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Section: Resultssupporting

confidence: 62%

“…3-6), according to the theoretical base [26,27]. Homogeneously broadened EPR lines for nonirradiated melanins were observed earlier [7,[11][12][13][17][18][19][20][21][22].…”

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Effect of UV irradiation on free radicals in synthetic melanin and melanin biopolymer from Sepia officinalis – EPR examination

Zdybel

Pilawa

2015

Nukleonika

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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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The nature of Cu(II) species in ATRP: New insights via EPR

Caretti

Dervaux

Prez

et al. 2010

J. Polym. Sci. A Polym. Chem.

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Identification of the paramagnetic species present in the Cu(I)Br‐catalyzed atom transfer radical polymerization (ATRP) of a model monomer (isobornyl acrylate) has been carried out by electron paramagnetic resonance (EPR) in the continuous wave mode at 90 K. Up to five different species—four copper‐based species and one organic radical—were detected with this technique. The EPR parameters of the copper‐based species are found to differ strongly, and originate from diverse isolated Cu(II) complexes, as well as dipolarly interacting and even exchange‐coupled Cu(II) species. The work highlights the complexity of the copper‐based EPR signal observed in copper‐mediated ATRP reactions. Analysis of the time evolution of the individual EPR contributions reveals the disadvantages of quantitative kinetics studies based on the summed EPR intensity of all copper‐based species, as is commonly used in literature for this type of reactions. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1493–1501, 2010

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EPR examination of Zn2+ and Cu2+ effect on free radicals in DOPA–melanin–netilmicin complexes

Cited by 30 publications

References 30 publications

Effect of UV irradiation on free radicals in synthetic melanin and melanin biopolymer from Sepia officinalis – EPR examination

Effect of UV irradiation on free radicals in synthetic melanin and melanin biopolymer from Sepia officinalis – EPR examination

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

The nature of Cu(II) species in ATRP: New insights via EPR

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