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1
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EPR examination of free radicals thermally formed invaselinum flavum

100%
Ramos P., Pilawa B.
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issue 3
443-447
EN
The popular pharmaceutical base used in pharmacy – vaselinum flavum – was studied by an X-band (9.3 GHz) EPR spectrometer in the range of microwave power of 2.2–70 mW. The samples were sterilized in hot air oven at temperatures: 160°C (120 min), 170°C (60 min), and 180°C (30 min). The aim of this work was to determine properties and free radical concentrations in vaselinum flavum thermally sterilized at different conditions. The changes in free radical system in vaselinum flavum during storage were analyzed. Free radicals were found in all the heated samples. The lowest free radical concentration was obtained for vaselinum flavum heated at 180°C for 30 min; so these parameters are proposed for the thermal sterilization of this pharmaceutical base. Interactions with oxygen decreased free radical concentration in vaselinum flavum during storage. Strong quenching of free radicals in vaselinum flavum was observed after 2 days for the samples sterilized at temperatures 160 and 180°C. Such an effect for vaselinum flavum heated at temperature 170°C was observed later, 13 days after sterilization. Fast spin-lattice relaxation processes exist in thermally sterilized vaselinum flavum. The EPR lines of heated vaselinum flavum were homogeneously broadened. EPR spectroscopy and its use for examining the thermal sterilization process in pharmacy was confirmed.
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Continuous microwave saturation of EPR spectra of melanin complexes at different temperatures

88%
Zdybel M., Pilawa B., Buszman E., Wrzesniok D., Krzyminiewski R., Kruczynski Z.
Polish Journal of Medical Physics And Engineering
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2011
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vol. 17
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issue 2
85-94
EN
Paramagnetic centers in DOPA-melanin and complexes of DOPA-melanin with netilmicin and Cu(II) were studied by the use of an X-band (9.3 GHz) electron paramagnetic resonance (EPR) spectroscopy. Measurements of continuous microwave saturation of EPR spectra at temperatures: 125 K, 175 K, 225 K, 275 K, were performed. Homogeneous broadening of all the examined EPR spectra was observed. EPR spectra of DOPA-melanin-Cu(II) complexes saturated at higher microwave powers than the others tested melanin samples. Fast spin-lattice relaxation exists in DOPA-melanin-Cu(II) complexes. Slow spin-lattice relaxation processes exist in melanin's paramagnetic centers of DOPA-melanin and its complexes with netilmicin, and its complexes with both netilimicin and Cu(II). EPR spectra of all the tested samples saturated at higher microwave powers with increasing of the measuring temperature. Faster spin-lattice relaxation processes occurs in DOPA-melanin and its complexes with netilmicin and Cu(II) at higher temperature.
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THE INFLUENCE OF STORAGE TEMPERATURE AND UV-IRRADIATION ON FREE RADICAL SCAVENGING PROPERTIES OF ETHANOLIC EXTRACTS OF PROPOLIS

88%
Komosińska-Vassev K., Olczyk P., Ramos P., Mencner L., Derkacz A., Waluga E., Krysik K., Olczyk K., Pilawa B.
Acta Poloniae Pharmaceutica - Drug Research
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2018
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vol. 74
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issue 6
1833-1840
EN
The free radical scavenging activity of ethanolic extracts of propolis (EEP) at the concentrations of 3%, 7%, and 10% was examined. The impact of storage temperature and exposure to ultraviolet (UV) light on the interactions of extracts of propolis with the model DPPH free radicals was also determined. The quenching of an X-band electron paramagnetic resonance spectra of DPPH free radicals by the extracts stored at room temperature, heated at the temperature of 50 oC and exposed to UV-irradiation, were compared. The examined propolis ethanolic extracts revealed an antioxidative character. The storage of the samples at a higher temperature (50 oC) caused a decrease of the scavenging activity equaling to 7% and 10% EEP. UV-irradiation of the 3% EEP increased the quenching of DPPH free radical lines. The reverse effect was observed for the 7% and 10% propolis extracts. The 3% ethanolic extract of propolis is more stable for storage at 50ºC, and less than other analyzed EEP susceptible for UV-irradiation. Alterations of the antioxidative properties of the analyzed EEP and changes in the kinetics of their interactions with free radicals, indicate that 3%, 7%, and 10% propolis extracts should not be exposed to the temperature of 50 oC and UV-irradiation.
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Preparation of N-aryl-ketonitrone spin traps

88%
Hassan I., Lauricella R., Tuccio B.
Open Chemistry
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2006
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vol. 4
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issue 2
338-350
EN
The syntheses of seven N-aryl-C,C-dialkoxycarbonylnitrones 1–7, six of which were original, were achieved from the appropriate aryl-nitroso compounds. These ketonitrones were found to trap efficiently carbon-centred free radicals in aqueous media, yielding stable aminoxyl radicals whose EPR spectra lasted several days. The two penta-deuterated compounds 6 and 7 were also found to be efficient at trapping methoxyl radical. Their various spin adducts showed simple three line signals, very sensitive to the polarity of the environment. This study represents the very first use of linear ketonitrones as spin traps.
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Oxidative stability of the lipid fraction in cookies – the EPR study

88%
Zawada K., Kozłowska M., Żbikowska A.
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issue 3
469-473
EN
Cookies are a group of convenient food products that are popular among consumers. They may contain high amounts of fats, which can be prone to oxidation. To retard the oxidative deterioration, synthetic and natural antioxidants may be added. Herb and spice extracts can be sources of natural biologically active substances with antioxidant activity. In this work, electron paramagnetic resonance spectroscopy was used to monitor the lipid oxidation in cookies with rosemary and thyme extracts subjected to the storage in elevated temperature. It was shown that thyme extract can be used as a natural antioxidant source for the preparation of bakery products, while the rosemary extract should be used with care in fat-rich products exposed to high temperatures.
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Effect of UV irradiation on free radicals in synthetic melanin and melanin biopolymer fromSepia officinalis– EPR examination

88%
Zdybel M., Pilawa B.
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issue 3
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.
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Synthesis, characterization and structure of the Bis(methyl-cyclopentadienyl)vanadium(IV) carboxylates

88%
Vinklarek J., Honzíĉek J., Císařová I., Pavliŝta M., Holubová J.
Open Chemistry
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2005
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vol. 3
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issue 1
157-168
EN
The 1,1’-dimethylvanadocene dichloride ((C5H4CH3)2VCl2) reacts in aqueous solution with various carboxylic acids giving two different types of complexes. The 1,1’-dimethylvanadocene complexes of monocarboxylic acids (C5H4CH3)2V(OOCR)2 (R=H,CCl3, CF3, C6H5) contain two monodentate carboxylic ligands, whereas oxalic and malonic acids act as chelate compounds of the formula (C5H4CH3)2V(OOC-A-COO) (A=−, CH2). The structure of the (C5H4CH3)2 V(OOCCF3)2 complex was determined by single crystal X-ray diffraction analysis. The isotropic and anisotropic EPR spectra of all the complexes prepared were recorded. The obtained EPR parameter values were found to be in agreement with proposed structures.
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Action of Some Organomercury Compounds on Photosynthesis in Spinach Chloroplasts

75%
Šeršeň F., Kráľová K.
Ecological Chemistry and Engineering S
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2013
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vol. 20
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issue 3
489-498
EN
The effects of five organomercury compounds (methylmercuric chloride, phenylmercuric acetate, phenylmercuric borate, phenylmercuric citrate and diphenylmercury) on photosynthetic electron transport (PET) in spinach chloroplasts were investigated. The IC50 values of organomercury compounds related to PET inhibition in spinach chloroplasts varied in the range from 468 mmol dm-3 to 942 mmol dm-3 and were approximately by one order higher than the corresponding value determined for HgCl2 applied also in DMSO solution (IC50 = 58 mmol dm-3). Due to extremely low aqueous solubility of diphenylmercury, the corresponding IC50 value could not be determined. Using EPR spectroscopy as probable sites of action of organomercury compounds in photosynthetic apparatus ferredoxin on the acceptor side of PS 1 and the quinone electron acceptors QA or QB on the reducing side of PS 2 were suggested.
PL
Zbadano wpływ pięciu związków rtęcioorganicznych (chlorku metylortęci, octanu fenylortęci, boranu fenylortęci, cytrynianu fenylortęci i difenylortęci) na fotosyntetyczny transport elektronów (PET) w chloroplastach szpinaku. Wartości IC50 dla związków rtęcioorganicznych związanych z inhibicją PET w chloroplastach szpinaku zmieniała się w zakresie od 468 do 942 μmol dm-3 i była w przybliżeniu o rząd większa od odpowiedniej wartości określonej dla HgCl2, stosowanego również w roztworze DMSO (IC50 = 58 μmol dm-3). Ze względu na bardzo małą rozpuszczalność difenylortęci w wodzie odpowiednia wartość IC50 nie może być określona. Wyniki badań za pomocą spektroskopii EPR pozwoliły na zaproponowanie prawdopodobnych miejsc działania związków rtęci w procesie fotosyntezy ferredoksyny po stronie akceptora PS 1 i chinonowego akceptora elektronów QA lub QB po stronie redukującej PS 2.
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Effects of storage conditions on formation of free radicals in soybean extract – an EPR spectroscopy study

75%
Jarco S.
Annales Academiae Medicae Silesiensis
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2017
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vol. 71
217-224
EN
OBJECTIVE: Soybean extract is a valuable food supplement used for the prevention of cancer and other purposes. The role of free radicals in carcinogenesis has been proven. Studies have also confirmed the effect of storage conditions on the formation of free radicals in natural medicinal products. The study presents an attempt to optimize the storage conditions of soybean extract to prevent the formation of free radicals. AIM OF THE STUDY: The aim of the study was to determine the effect of temperature and UV radiation on the formation of free radicals in soybean extract during storage. MATERIAL AND METHODS: Samples of soybean extract were heated to temperatures of 30, 40 and 50°C. Subsequent samples were exposed to UV radiation (wavelengths 315–400 nm) for 30 and 60 minutes. EPR (electron paramagnetic resonance) spectroscopy was used to analyse the amplitude and linewidth of the EPR signal and to calculate the concentration of free radicals in the samples. RESULTS: At a room temperature of 25°C and in the absence of light, no EPR signal was recorded for the tested samples. Heating and exposure to UV light caused the formation of free radicals in the samples. The highest concentration of free radicals was found in the sample exposed to UV light for 60 minutes, while the lowest was in the sample heated to 30°C. CONCLUSIONS: The use of EPR spectroscopy enabled the identification of optimal storage conditions for soybean extract, i.e. 25°C and darkness.
PL
WSTĘP: Cennym uzupełnieniem diety jest wyciąg z nasion soi, wykorzystywany między innymi w profilaktyce nowotworów. Udział wolnych rodników w procesach karcynogenezy został udowodniony. Badania potwierdzają wpływ warunków przechowywania naturalnych środków leczniczych na zachodzące w nich zjawiska wolnorodnikowe. W pracy podjęto próbę optymalizacji warunków przechowywania wyciągu z nasion soi, aby zapobiec powstawaniu w nim wolnych rodników. CEL PRACY: Celem pracy było określenie wpływu temperatury i promieniowania UV na generowanie wolnych rodników w wyciągu z nasion soi w trakcie przechowywania. MATERIAŁ I METODY: Próbki z wyciągiem z nasion soi ogrzewano w temperaturach 30, 40 i 50°C. Kolejne próbki naświetlano promieniowaniem UV (długość fali 315–400 nm) przez 30 i 60 minut. Wykorzystano spektroskopię EPR (elektron paramagnetic resonance), analizując amplitudę i szerokość linii EPR oraz obliczając koncentrację wolnych rodników w próbkach. WYNIKI: W temperaturze pokojowej 25°C oraz przy braku dostępu światła nie rejestrowano sygnału EPR dla testowanych próbek. Ogrzewanie próbek oraz ekspozycja na promieniowanie UV powodowały pojawienie się w nich wolnych rodników. Największą koncentrację wolnych rodników stwierdzono w próbce naświetlanej UV przez 60 minut, najniższe zaś w próbce ogrzanej do 30°C. WNIOSKI: Wykorzystanie spektroskopii EPR pozwoliło na ustalenie optymalnych warunków przechowywania wyciągu z nasion soi, którymi są temperatura 25°C oraz brak dostępu światła.
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EPR study of free radicals formed in fusidic acid and neomycin under UV irradiation

75%
Pierzchała E., Ramos P., Pilawa B.
Acta Poloniae Pharmaceutica - Drug Research
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2019
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vol. 76
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issue 2
215-223
EN
Free radicals in UV irradiated antibiotics used in dermatology were examined. Concentrations of free radicals in fusidic acid and neomycin, were determined. EPR spectra of the tested antibiotics were measured by electron paramagnetic resonance spectrometer with magnetic modulation of 100 kHz and numerical acquisition system the Rapid Scan Unit. The influence of microwave powers in the range of 2.2-70 mW on the spectra was obtained. Amplitudes (A) and linewidths (ΔBpp) of the EPR spectra, were analysed. The EPR spectra were homogeneously broadened. Fast spin-lattice relaxation processes existed in UV irradiated fusidic acid and neomycin, which EPR spectra were not saturated up to 70 mW. The influence of the time of UV irradiation on free radicals in the samples was observed. The samples were irradiated by UVA (315-400 nm) in the 30, 60, and 90 minute period. Free radical concentrations in the tested antibiotics exposed to UV were proportional to the amplitudes (A) of the EPR spectra. The highest amplitudes (A) were observed for the UV irradiated antibiotics during 60 minutes. The higher amplitudes (A) characterized fusidic acid than neomycin. Fusidic acid and neomycin used to treat bacterial infection of skin under UV irradiation may produce free radical toxic effects. The stronger photosensitivity characterized fusidic acid relatively to neomycin. EPR spectroscopy is the useful method to examine free radicals formed in antibiotics during photolysis.
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Free radical formation in salicylic acid and heating parameters – application of EPR, UV-Vis, TGA and colorimetry examination to optimize thermal sterilization

75%
Ramos P., Pilawa B.
Acta Poloniae Pharmaceutica - Drug Research
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2020
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vol. 77
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issue 3
431-441
EN
Salicylic acid heated at different temperatures and times was examined by an X-band (9.3 GHz) EPR spectroscopy, UV-Vis spectrophotometry, TGA and colorimetry test to optimize its thermal sterilization process. Free radical formation (~1018 spin/g) during thermal sterilization of salicylic acid according to the pharmaceutical norms at temperature 120oC and time of 120 minutes was compared with those for heating at the new tested temperatures and times: 130oC and 60 minutes, and 140oC and 30 minutes. It was obtained that the relatively lower free radical concentrations characterized salicylic acid heated at temperatures (times): 120oC (120 minutes), and 130oC (60 minutes), than at temperature (time) 140oC (30 minutes). So treatment at temperature 120oC during 120 minutes, and temperature 130oC during 60 minutes, were recommended as the optimal for thermal sterilization of salicylic acid. Salicylic acid should not be sterilized at temperature 140oC during 30 minutes, because of the highest free radical formation. Free radical systems of thermally treated salicylic acid revealed complex character. Fast spin-lattice relaxation processes existed in heated salicylic acid. Strong dipolar interactions characterized all the heated salicylic acid samples. EPR spectroscopy, UV-Vis spectrophotometry, thermogravimetry, and color measurement may be helpful besides microbiological analysis to optimize thermal sterilization conditions of salicylic acid.
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Multifrequency EPR study on radiation induced centers in calcium carbonates labeled with13C

75%
Sadło J., Bugaj A., Strzelczak G., Sterniczuk M., Jaegermann Z.
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issue 3
429-434
EN
In calcite and aragonite, γ-irradiated at 77 K, several paramagnetic centers were generated and detected by EPR spectroscopy; in calcite, CO3− (orthorhombic symmetry, bulk and bonded to surface), CO33−, NO32−, O3−, and in aragonite CO2− (isotropic and orthorhombic symmetry) depending on the type of calcium carbonate used. For calcium carbonates enriched with 13C more detailed information about the formed radicals was possible to be obtained. In both natural (white coral) and synthetic aragonite the same radicals were identified with main differences in the properties of CO2− radicals. An application of Q-band EPR allowed to avoid the signals overlap giving the characteristics of radical anisotropy.
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Inclusion compounds of cystostatic active (C5H5)2VCl2 and (CH3C5H4)2VCl2 with α-, β- and γ-cyclodextrines: Synthesis, EPR study and microbiological behavior toward Escherichia coli

75%
Vinklárek J., Honzíček J., Holubová J.
Open Chemistry
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2005
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vol. 3
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issue 1
72-81
EN
The inclusion of vanadocene dichloride (VDC) and 1,1′-dimethyl vanadocene dichloride (MeVDC) into cyclodextrines (α-CD, β-CD and γ-CD) was studied by EPR spectroscopy. It was found that VDC and MeVDC with β-CD and γ-CD form true inclusion compounds, but with α-CD, VDC and MeVDC gave only fine dispersion mixtures. The inclusion was validated by anisotropic EPR spectra of solid samples. In addition, the antimicrobial was validated by anisotropic EPR spectra of solid samples. In addition, the antimicrobial behavior (against E. coli) of each of the complexes was determined. It was established that not only did VDC and MeVDC cause elongation of E. coli, but also the new vanadocene inclusion complexes were effective in this regard.
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Zastosowanie spektroskopii EPR do badania wolnych rodników generowanych termicznie w drotawerynie

63%
Ramos P., Pilawa B., Adamski M.
Annales Academiae Medicae Silesiensis
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2014
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vol. 68
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issue 1
28-37
EN
INTRODUCTION Microorganisms should be removed from drugs during their production, however, sterilization processes should not produce free radicals. Free radicals in drotaverine were studied. The applicability of thermal sterilization for drotaverine was investigated. MATERIAL AND METHODS Drotaverine heated to 160oC was examined by the EPR method. Free radical concentration, their distribution in the sample, the complex character of the free radical system and magnetic spin-spin interactions in the drug were determined. Changes in the free radical concentration in drotaverine during storage after sterilization also were examined. The sterilization conditions were chosen according to pharmakopeal norms. The analysed drug was sterilized in dry hot air. RESULTS EPR lines were not obtained for drotaverine before sterilization. It was demonstrated that drotaverine after thermal sterilization at temperature 160oC contains free radicals and exhibits EPR spectra. The free radical concen-tration in drotaverine changes with storage time after thermal treatment. Interactions with oxygen are probably responsible for this effect. The free radicals are homogeneously distributed in drotaverine since characteristic correlations between the amplitudes and linewidths of the EPR lines and microwave power were observed. The free radicals are closely located to one another in drotaverine and they strongly interact in a dipolar manner, which cause broadening of the EPR spectra. Continuous microwave saturation of the EPR spectra revealed that slow spin-lattice relaxation processes occur in thermally sterilized drotaverine. The shape of the EPR spectra and asymmetry parameters of the test drug change with increasing microwave power, indicating the complex nature of the free radicals in the sample. CONCLUSIONS Drotaverine should not be thermally sterilized because of free radical formation. The obtained results confirmed the usefulness of EPR spectroscopy to examine thermally sterilized drugs. The EPR method may be used as a supplement to microbiological tests.
PL
WSTĘP Leki wymagają usunięcia drobnoustrojów podczas ich produkcji, jednak procesy sterylizacji nie powinny generować wolnych rodników. Zbadano wolne rodniki w drotawerynie. Sprawdzono, czy sterylizacja termiczna może być w tym przypadku stosowana. MATERIAŁY I METODY Zbadano drotawerynę ogrzewaną w 160oC metodą EPR. Wyznaczono koncentrację wolnych rodników, określono sposób ich rozmieszczenia w ogrzanej próbce, złożoność układu wolnorodnikowego oraz oddziaływania magnetyczne spin-spin. Zbadano również zmiany koncentracji wolnych rodników w drotawerynie podczas przechowywania leku po sterylizacji. Warunki sterylizacji termicznej wybrano zgodnie z obowiązującymi normami farmakopealnymi. Lek sterylizowano suchym gorącym powietrzem. WYNIKI Nie uzyskano linii EPR dla drotaweryny przed sterylizacją. Wykazano, że drotaweryna po sterylizacji termicznej w temp. 160oC zawiera wolne rodniki i wykazuje widma EPR. Koncentracja wolnych rodników w drotawerynie zmienia się wraz z czasem przechowywania leku po obróbce termicznej. Za efekt ten odpowiadają prawdopodobnie oddziaływania z tlenem. Wolne rodniki w drotawerynie rozmieszczone są jednorodnie, ponieważ zaobserwowano charakterystyczne dla tego przypadku zależności amplitudy i szerokości linii EPR od mocy mikrofalowej. Wolne rodniki w drotawerynie są położone blisko siebie i silnie oddziałują dipolowo, co powoduje poszerzenie widm EPR. Ciągłe nasycenie mikrofalowe widm EPR wykazało, że w drotawerynie sterylizowanej termicznie zachodzą wolne procesy relaksacji spin-sieć. Kształt widm EPR i parametry asymetrii testowanego leku zmieniają się wraz ze wzrostem mocy mikrofalowej, co wskazuje na złożony charakter układu wolnych rodników w próbce. WNIOSKI Drotaweryna nie powinna być sterylizowana termicznie ze względu na generowanie wolnych rodników. Uzyskane rezultaty potwierdziły przydatność spektroskopii EPR do badania leków sterylizowanych termicznie. Metoda EPR może być wykorzystana jako uzupełnienie testów mikrobiologicznych.
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Zastosowanie spektroskopii EPR w badaniach jakościowych i ilościowych centrów paramagnetycznych melanin

51%
Chodurek E., Barbara B.
Annales Academiae Medicae Silesiensis
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2022
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issue 76
21-30
EN
Electron paramagnetic resonance (EPR) spectroscopy is a method useful in biology and medicine to examine paramagnetic substances, their role in disease processes and therapy. The aim of this review work is to present the physical foundations of EPR spectroscopy and to review the applications of the EPR method for the qualitative and quantitative research on paramagnetic centers in melanin. The possibilities of EPR spectroscopy and experimental procedures applied to determine the types of paramagnetic centers existing in synthetic melanin and in melanin biopolymers are discussed. A useful spectroscopic parameter to determine the type of paramagnetic centers is the spectroscopic cleavage coefficient g, which depends on the location of the unpaired electron in the molecule. o-Semiquinone free radicals with spin S = 1/2 and biradicals with spin S = 1, exist in melanin. Free radicals and biradicals can be distinguished spectroscopically by analysing the influence of temperature on the integral intensity of EPR lines. The concentration of paramagnetic centers in melanin is proportional to the intensity of the integral EPR spectrum. The influence of paramagnetic and diamagnetic metal ions, and oxygen on the concentration of paramagnetic centers in melanin is presented. The publications on the influence of medicinal substances on the concentration of paramagnetic centers in tumor cells were reviewed. The usefulness of EPR spectroscopy in identifying melanin in biological samples, among others, cancer cells, bacteria, and fungi, is presented.
PL
Spektroskopia elektronowego rezonansu paramagnetycznego (electron paramagnetic resonance – EPR) jest metodą przydatną w biologii i medycynie do badania substancji paramagnetycznych, ich roli w procesach chorobowych oraz terapii. Celem pracy jest przedstawienie podstaw fizycznych spektroskopii EPR oraz dokonanie przeglądu zastosowań metody EPR do badań jakościowych i ilościowych centrów paramagnetycznych melanin. Omówiono możliwości spektroskopii EPR i procedury eksperymentalne stosowane do wyznaczenia rodzajów centrów paramagnetycznych występujących w melaninach syntetycznych oraz w biopolimerach melaninowych. Parametrem spektroskopowym przydatnym do określenia rodzaju centrów paramagnetycznych jest współczynnik rozszczepienia spektroskopowego g, który zależy od lokalizacji niesparowanego elektronu w cząsteczce. W melaninach występują o-semichinonowe wolne rodniki o spinie S = 1/2 oraz birodniki o spinie S = 1. Wolne rodniki i birodniki można odróżnić spektroskopowo poprzez analizy wpływu temperatury pomiaru na intensywność integralną linii EPR. Koncentracja centrów paramagnetycznych w melaninie jest proporcjonalna do intensywności integralnej widma EPR. Przedstawiono wpływ paramagnetycznych i dia-magnetycznych jonów metali oraz tlenu na koncentrację centrów paramagnetycznych w melaninie. Dokonano przeglądu publikacji dotyczących wpływu substancji leczniczych na koncentrację centrów paramagnetycznych w melaninie. Przedstawiono przydatność spektroskopii EPR w identyfikowaniu melaniny w próbkach biologicznych, m.in. komór-kach nowotworowych, bakteriach i grzybach.
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