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1
Content available The acid-catalyzed interaction of melanin with nitrite ions : an EPR investigation
Matuszak Z., Chignell C. F., Reszka K. J.
Nukleonika
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2015
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Vol. 60, No. 3, part 1
475--481
EN
The interaction of synthetic dihydroxyphenylalanine (DOPA) melanin (DM) with nitrite ions, NO2 –, in the pH 3.6–7.0 range, has been investigated using electron paramagnetic resonance (EPR). We found that especially at pH <5.5 (from ca. 5.5 to 3.6) the reaction of DM with nitrite generated large quantities of new melanin radicals, which implies the involvement of nitrous acid, HNO2, in the radical formation process. Measurements carried out at constant pH of 3.6 showed that the melanin signal increased together with nitrite concentration, reaching a plateau level which was more than fourfold larger compared to the initial signal amplitude observed in a nitrite-free buffer of the same pH. The effects of nitrite and DM concentrations on the melanin-free radical content were also investigated. It is proposed that the radicals are generated by one electron oxidation of melanin ortho-hydroquinone groups to ortho-semiquinones by HNO2 or related nitrogen oxides such as NO2 • radicals. The possible involvement of nitric oxide (•NO) and peroxynitrite (ONOO–) in DM oxidation was also examined. In air-free solutions, nitric oxide per se did not generate melanin radicals; however, in the presence of oxygen a marked increase in the melanin EPR signal intensity was observed. This result is interpreted in terms of the generation of radicals via the oxidation of DM by peroxynitrite. Our fi ndings suggest that melanin can function as a natural scavenger of nitrous acid and some nitrous acid-derived species. This property may be relevant to physiological functions of melanin pigments in vivo.
2
Content available Effect of UV irradiation on free radicals in synthetic melanin and melanin biopolymer from Sepia offi cinalis : EPR examination
Zdybel M., Pilawa B.
Nukleonika
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2015
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Vol. 60, No. 3, part 1
483--488
EN
Free radicals in synthetic melanin and melanin from Sepia officinalis 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 (~1021–1022 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 officinalis than in synthetic melanin. UV irradiation did not change the time of spin-lattice relaxation processes in the tested melanins. The performed studies confirmed the usefulness of EPR spectroscopy in cosmetology and medicine.
3
Content available EPR study of γ-irradiated feather keratin and human fingernails concerning retrospective dose assessment
Strzelczak G., Sterniczuk M., Sadło J., Kowalska M., Michalik J.
Nukleonika
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2013
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Vol. 58, No. 4
505--509
EN
In this paper we report the results of comparative EPR studies on free radicals generated in γ-irradiated powder samples of feather keratin powder and human fingernails. In degassed samples of both materials irradiated at 77 K the major component of EPR spectrum represents sulphur-centred radicals in cysteine residues. It quickly decays after air admission at room temperature while a singlet assigned to semiquinone melanin radicals remains the only one seen. The singlet recorded with fingernails decays slowly at room temperature and might be potentially useful for dose assessment by EPR. The advantages and limitations of fingernails EPR dosimetry are discussed.
4
Content available EPR studies of Cladosporium cladosporioides complexes with amphotericin B
Zdybel M., Pilawa B., Buszman E., Witoszyńska T.
Nukleonika
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2013
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Vol. 58, No. 3
401--405
EN
Free radicals in Cladosporium cladosporioides cultured with amphotericin B were spectroscopically studied. The effect of drug concentrations on free radicals in the fungal melanin biopolymer was examined. It was pointed out that the concentrations of free radicals in the complexes of Cladosporium cladosporioides mycelium with amphotericin B depend on the drug concentrations. Eumelanin dominates in the fungal studied samples. The slow spin-lattice relaxation processes exist in the tested samples. Free radicals take a part in the formation of Cladosporium cladosporioides mycelium complexes with amphotericin B.
5
Content available remote Photodynamic therapy of melanoma. Monte Carlo modeling of light transport in human pigmented skin
Matuszak Z.
Bio-Algorithms and Med-Systems
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2011
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Vol. 7, no. 2
85--93
EN
Among many available methods used in clinical practice to treat cancer tissues, Photodynamic therapy (PDT) is a relatively new tool. PDT is an enhancement of chemotherapy. To destroy cancerous tissue, photosensitizer (PS), oxygen (O2) and light - three crucial elements of PDT - have to work together to produce sufficiently high concentration of cytotoxic reagents, reactive species of oxygen (ROS), mainly singlet oxygen 1O2. To effectively generate 1O2, light intensity needed for the activation PS should achieve appropriate value in the place of the location of PS within the cancerous lesion. In pigmented cancers amount of melanin is larger than in normal tissues due to proliferation of melanoma cells. Melanin strongly absorbs light and attenuates its intensity. To investigate the influence of melanin on PDT efficiency, a seven-layer computer skin model was proposed and tentatively examined in this work. Influence of melanin on light intensity distribution was simulated with Monte Carlo method. For some fluence rate values (50,100,150 and 200 mWcm-2) the computer simulations of PDT effect using parameters of porphyrin photosensitizer (tritiolyloporphyrin, λex=650 nm) and kinetic schema of PDT based on Jablonski diagram were analyzed. Simulations have shown that fluence rate values strongly modify efficiency of therapy and in the case of low fluence rate values deeper laying cancerous cell would not be killed due to too low 1O2 production. Additionally it was shown that the problem of estimation of melanin content in tissue can be solved by measurement of diffuse reflectance of skin. The possibilities of further development of the model were also briefly discussed.
6
Content available Wpływ flucytozyny na właściwości paramagnetyczne Cladosporium cladosporioides
Pilawa B., Zdybel M., Buszman E., Witoszyńska T., Cieśla H.
Engineering of Biomaterials
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2009
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Vol. 12, no. 89-91
167--169
PL
Zbadano właściwości paramagnetyczne upigmentowanych grzybów glebowych Cladosporium cladosporioides oraz ich kompleksów z flucytozyną z zastosowaniem spektroskopii EPR. Eumelanina występująca w Cladosporium cladosporioides odpowiada głównie za ich silne sygnały EPR. Flucytozyna zwiększa koncentrację o-semichinonowych wolnych rodników w melaninie Cl. cladosporioides. Wolne procesy relaksacji spin-sieć zachodzą w Cladosporium cladosporioides.
EN
Paramagnetic properties of pigmented soil fungi Cladosporium cladosporioides and their complexes with flucytosine were studied by EPR spectroscopy. Eumelanin of Cladosporium cladosporioides is mainly responsible for their strong EPR signals. Flucytosine increases o-semiquinone free radicals concentration in melanin of Cl. cladosporioides. Slow spin-lattice relaxation processes exist in Cladosporium cladosporioides.
7
Content available Paramagnetyzm upigmentowanych grzybów glebowych Cladosporium herbarum
Zdybel M., Pilawa B., Buszman E., Witoszyńska T., Brotoń B.
Engineering of Biomaterials
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2009
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Vol. 12, no. 89-91
172--174
PL
Zbadano właściwości centrów paramagnetycznych upigmentowanych grzybów glebowych Cladosporium herbarum metodą EPR. Stwierdzono stabilny paramagnetyzm Cladosporium herbarum wynikający z obecności w próbce głównie eumelaniny. W widmach EPR obserwowano dominującą linię eumelaniny oraz dodatkowo linię feomelaniny o niewielkiej amplitudzie. o-Semichinonowe wolne rodniki (~10/17spin/g) odpowiadają za paramagnetyzm Cladosporium herbarum.
EN
Properties of paramagnetic centers in pigmented soil fungi Cladosporium herbarum were studied by EPR method. Stable parmagnetism of Cladosporium herbarum, mainly resulted from existence of eumelanin in the sample, was stated. Dominant line of eumelanin and additionally line of pheomelanin with the low amplitude were observed in EPR spectra. o-Semiquinone free radicals (~10/17spin/g) are mainly responsible for paramgnetism of Cladosporium herbarum.
8
Content available Modelowe badania EPR wpływu stężenia leku na właściwości centrów paramagnetycznych w kompleksach biopolimeru melaninowego z netilmicyną
Pilawa B., Zdybel M., Buszman E., Wrześniok D., Mrochen J.
Engineering of Biomaterials
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2008
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Vol. 11, no. 81-84
65--66
PL
Melanina jest ciemnym pigmentem powszechnie występującym w organizmach roślinnych i zwierzęcych. U człowieka występuje w skórze, włosach, oczach, uchu wewnętrznym, ośrodkowym układzie nerwowym [1,2]. W organizmach żywych występuje głównie wybrana do badań eumelanina (RYS. 1). Jest to grupa melanin o zabarwieniu brązowo-czarnym [1,2]. Kolejną grupę stanowią feomelaniny o barwie czerwono-brązowej, które zawierają siarkę oraz allomelaniny [1,2 ]. Melanina to biopolimer wykazujący wysokie powinowactwo do jonów metali oraz substancji leczniczych [1-4]. Długotrwała ekspozycja lub wysoko-dawkowa terapia substancjami leczniczymi może prowadzić do nadmiernej kumulacji tych substancji w melaninie, a w konsekwencji do degradacji upigmentowanych tkanek [3,4]. Celem niniejszej pracy jest określenie wpływu stężenia leku na koncentrację i właściwości centrów paramagnetycznych występujących w kompleksach DOPA-melaniny - eumelaniny z przykładowym antybiotykiem - netilmicyną. Widma EPR kompleksów DOPA- melanina-netilmicyna mierzono z wykorzystaniem spektrometru elektronowego rezonansu paramagnetycznego na pasmo X (9.3GHz) w temperaturze pokojowe w szerokim zakresie mocy mikrofalowej wynoszącym 0.7-70mW. Zastosowano następujące stężenia netimicyny w analizownaych kompleksach: 1x104M, 5x104 M, 1x10-3 M, 5x1Cr3 M oraz 1x10-2 M. Wyznaczono koncentrację centrów paramagnetycznych, współczynnik rozszczepienia spektroskopowego g, amplitudę i szerokość linii EPR. Zbadano wpływ mocy mikrofalowej na nasycenie mi¬krofalowe widm EPR kompleksów melaninowych. Wszystkie badane kompleksy melaninowe charakteryzuje wysoka koncentracja centrów paramagnetycznych z zakresu 1.6-2.2x1019spin/g. Koncentracja centrów paramagnetycznych w kompleksach DOPA-melanina-netilmicyna zależy od stężenia leku. Najmniejsza wartość koncentracji centrów paramagnetycznych otrzymano w przypadku kompleksów o stężeniu netilmicyny 5x104 M. Rejestrowane widma EPR stanowiły szerokie asymetryczne linie o wartościach szerokości sygnału z zakresu 0.45-0.48mT. Dla wszystkich próbek otrzymano wartość współczynnika g=2.0043 charakterystyczną dla o-semichinonowych wolnych rodników. Zmiany amplitudy i szerokości linii EPR wraz ze wzrostem mocy mikrofalowej dla DOPA-melaniny oraz przykładowego kompleksu DOPA-melanina-netilmicyna pokazano odpowiednio na RYSUNKACH 2 i 3. Stwierdzono spadek amplitudy dla wyższych mocy mikrofalowych (RYS. 2). Szerokość linii EPR rośnie wraz ze wzrostem mocy mikrofalowej (RYS. 3). Korelacje przedstawione na RYSUNKACH 2 i 3 wskazują na jednorodne poszerzenie linii EPR [4-6]. Podobne korelacje otrzymano dla wszystkich badanych kompleksów.
EN
Melanin is a pigment in the plants or animals. In humans, melanin biopolymer is found in skin, hair, the iris, inner ear and nervous system [1,2]. The most common form of biological melanin is eumelanin (FIG. 1). It is a brown-black polymer. Another common form of melanin is pheomelanin. It is a red-brown polymer [1,2]. Melanin can bind medical drugs and metal ions [1-4]. Interactions of high doses of drugs with melanins may be responsible for many toxic effects in pigmented tissues, e.g. toxic retinopathy, hyperpigmentation of the skin, hair bleaching and some ocular and inner ear lesions [3,4]. The aim of this work was to determine influence of drug concentration on the amount and properties of paramagnetic centres existing in complexes of DOPA-melanin - eumelanin with exemplary antibiotic - netilmicin. EPR spectra of DOPA-melanin-netilmicin complexes were measured by the use of an X-band (9.3GHz) electron paramagnetic resonance spectrometer at room temperature in the wide range of microwave power (0.7-70mW). The following concentrations of netilmicin in the analyzed complexes were applied: 1x10-4 M, 5x10т4 M, 1x103 M, 5x103 M and 1x102 M. Paramagnetic centres concentration, g-factor, amplitude and linewidth of EPR spectra were evaluated. We determined the effect of continuous microwave saturation on melanins EPR spectra. All the studied melanins complexes characterized high paramagnetic centres concentrations 1.6- 2.2x1019spin/g. The concentrations of paramagnetic centres in DOPA-melanin-netilmicin complexes depend on drug concentration. The lowest paramagnetic centres concentration was obtained for complexes with netilmicin concentration of 5x10-4M. The measured EPR spectra were broad assymetrical lines with linewidths in the range 0.45-0.48mT. g-Factor of 2.0043 characteristic for o-semiquinone free radicals was obtained for the samples. Changes of amplitude and linewidths of EPR lines of DOPA-melanin and the exemplary DOPA-melanin-netilmicin complex with increasing of microwave power are compared in FIGURES 2 and 3, respectively. Decrease of amplitudes for the higher microwave powers were observed (FIG. 2). Linewidths increase with increasing of microwave power (FIG. 3). Correlations presented in FIGURES 2 and 3 indicate that the EPR spectra are homogeneously broadened [4-6]. Similar correlations were obtained for all the examined complexes.
9
Content available remote Chernobyl effect : growth characteristics of soil fungi Cladosporium cladosporioides (Fresen) De Vries with and without positive radiotropism
Zdanova N., Fomina M., Redchitz T, Olsson S.
Polish Journal of Ecology
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2001
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Vol. 49, nr 4
309-318
EN
Positive radiotropism is common in fungi isolated from the area of the Chernobyl power plant. The aim was to study the submerged growth of one of these fungi, strains of Cladosporium cladosporioides, to search for correlations between positive radiotropic reaction and melanin synthesis with growth responses under low-level gamma-irradiation. In contrast to control strains the conidial germination of Chernobyl strains was not affected by the radiation treatment. The highest level of biomass melanin and of inhibitory constant was found for one of the Chernobyl strains. The characteristics of the Chernobyl strains indicated an adaptation to an environment with ionizing radiation.
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