scholarly journals Electron Paramagnetic Resonance Examination of Free Radical Formation in Salicylic Acid and Urea Exposed to UV Irradiation

2016 ◽  
Vol 2016 ◽  
pp. 1-7
Author(s):  
Paweł Ramos ◽  
Barbara Pilawa
Keyword(s):  
Salicylic Acid ◽  
Free Radicals ◽  
Free Radical ◽  
Uv Irradiation ◽  
Epr Spectroscopy ◽  
Irradiation Time ◽  
Spin Lattice Relaxation ◽  
Spin Lattice ◽  
Radical Concentration ◽  
Free Radical Concentration

Free radicals formed by UV irradiation of the two magistral formulas applied on the skin, salicylic acid and urea, were examined by X-band (9.3 GHz) EPR spectroscopy. The influence of the time of UVA (315–400 nm) irradiation on free radical properties and concentrations in the drug samples was determined. The nonirradiated magistral formula did not contain free radicals. Amplitudes (A) and linewidths (ΔBpp) of EPR spectra were analysed. Fast spin-lattice relaxation process existed in the tested drugs. UV irradiation did not change spin-lattice interactions in the tested magistral formula. Concentrations of free radicals formed by UV irradiation in salicylic acid and urea were ~1017–1018 spins/g. The strongest formation of free radicals under UV irradiation was observed for salicylic acid than for urea. Free radical concentration in salicylic acid increased with the increase of UV irradiation time from 15 minutes to 30 minutes, and after its value remained unchanged. The increase of free radical concentration in urea with UV irradiation time was stated. Salicylic acid is characterized with higher photosensitivity than urea. Salicylic acid, urea, and the skin treated by them should not be stored on UV exposure. The usefulness of EPR spectroscopy to optimize storage conditions of recipe drugs was conformed.

scholarly journals Effect of microwave power on EPR spectra of thermally sterilized eucerinum anhydricum

Nukleonika ◽  
2015 ◽  
Vol 60 (3) ◽  
pp. 439-442 ◽  
Author(s):  
Paweł Ramos ◽  
Piotr Pepliński ◽  
Barbara Pilawa
Keyword(s):  
Free Radicals ◽  
Free Radical ◽  
Microwave Power ◽  
Spin Lattice Relaxation ◽  
Epr Spectra ◽  
Relaxation Processes ◽  
Spin Lattice ◽  
Radical Concentration ◽  
Free Radical Concentration ◽  
Thermal Sterilization

Abstract Free radicals formed during thermal sterilization of eucerinum anhydricum – the pharmaceutical base were examined by an X-band (9.3 GHz) spectrometer. Eucerinum anhydricum was sterilized at different physical conditions according to the Polish Pharmacopeia norms. The samples were heated at temperatures: 160°C (120 min), 170°C (60 min), and 180°C (30 min). The aim of this study is to compare free radical concentration and effect of microwave power on EPR spectra of eucerinum anhydricum base thermally sterilized at different temperatures and periods of time. The effect of time storage on the free radicals in the heated samples was tested. Free radical concentrations in the sample stored 15 min strongly decreased with the increasing of sterilization temperature, probably as the result of recombination. Storage caused strong decrease of free radical concentrations in the samples, probably as the result of interactions with oxygen. It was observed to be independent of sterilization conditions from 2 days of storage and longer. Because of the lowest free radical concentration, for eucerinum anhydricum thermal sterilization at 180°C for 30 min is recommended. The sterilized samples should be stored at inert atmosphere without oxygen molecules. Fast spin-lattice relaxation processes existed in sterilized eucerinum anhydricum. The character of changes of amplitudes and linewidths of EPR lines with increasing of microwave power was the same for different storage times. The parameters of thermal sterilization and storage time influenced free radical concentration in eucerinum anhydricum, but magnetic spin-lattice interactions were unchanged. The usefulness of EPR spectroscopy in optimization of thermal sterilization process of eucerinum anhydricum was confirmed.

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

Nukleonika ◽  
2015 ◽  
Vol 60 (3) ◽  
pp. 483-488 ◽  
Author(s):  
Magdalena Zdybel ◽  
Barbara Pilawa
Keyword(s):  
Free Radicals ◽  
Free Radical ◽  
Uv Irradiation ◽  
Epr Spectroscopy ◽  
Microwave Power ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Relaxation Processes ◽  
Sepia Officinalis ◽  
Spin Lattice

AbstractFree radicals in synthetic melanin and melanin fromSepia officinaliswere 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 (~1021–1022spin/g) ofo-semiquinone free radicals withgfactors 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 fromSepia officinalisthan 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.

scholarly journals EPR examination of free radicals thermally formed in vaselinum flavum

Nukleonika ◽  
2015 ◽  
Vol 60 (3) ◽  
pp. 443-447 ◽  
Author(s):  
Paweł Ramos ◽  
Barbara Pilawa
Keyword(s):  
Free Radicals ◽  
Free Radical ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Relaxation Processes ◽  
Spin Lattice ◽  
Radical Concentration ◽  
Free Radical Concentration ◽  
Thermal Sterilization ◽  
C 30

Abstract 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.

Novel Bioadhesives for Restorative Dentistry

2008 ◽  
Vol 587-588 ◽  
pp. 682-686
Author(s):  
S.G. Pereira ◽  
J.P. Telo ◽  
R. Osorio ◽  
M. Toledano ◽  
Teresa G. Nunes
Keyword(s):  
Free Radical ◽  
Double Bond ◽  
Epr Spectroscopy ◽  
Stray Field ◽  
Restorative Dentistry ◽  
Radical Scavengers ◽  
Spatially Resolved ◽  
Radical Concentration ◽  
Free Radical Concentration ◽  
Double Bond Conversion

The objective of this study was to develop new adhesive formulations based on 2,2-bis[4-(2- methacryloxyprop-1-oxy) phenyl] propane (CH3-BisGMA) aiming to obtain high double bond conversion (DC) even in the presence of radical scavengers and monomers with acidic groups. NMR, EPR spectroscopy and spatially-resolved 1H Stray-Field MRI observations enabled to study the influence of the composition in DC, free radical concentration, reactivity of the monomers and volumetric contraction.

Improved DPPH determination for antioxidant activity spectrophotometric assay

2007 ◽  
Vol 61 (3) ◽  
Author(s):  
M. Szabo ◽  
C. Idiţoiu ◽  
D. Chambre ◽  
A. Lupea
Keyword(s):  
Antioxidant Activity ◽  
Free Radicals ◽  
Free Radical ◽  
Calibration Curve ◽  
Spectrophotometric Assay ◽  
Stable Form ◽  
Radical Concentration ◽  
Free Radical Concentration

AbstractAn improved procedure for determination of the residual DPPH (1,1-diphenyl-2-picrylhydrazyl) free radical concentration was proposed taking into account the absorbance of both DPPH free radicals and DPPH nonradical (1,1-diphenyl-2-picrylhydrazine) stable form. The calculated residual DPPH free radical concentrations were compared with those obtained from a calibration curve and variation coefficients below 10 % were found.

scholarly journals The influence of free-radical concentration on the shear bond strength of dental composites

2018 ◽  
Vol 52 (2) ◽  
pp. 177-182
Author(s):  
B. Kiteska ◽  
N. Funduk ◽  
P. Cevc ◽  
A. Jesih ◽  
A. Anžlovar ◽  
...  
Keyword(s):  
Free Radical ◽  
Bond Strength ◽  
Shear Bond Strength ◽  
Dental Composites ◽  
Radical Concentration ◽  
Free Radical Concentration

Magnesium reduces free radical concentration and preserves left ventricular function after direct current shocks

Resuscitation ◽  
2003 ◽  
Vol 56 (2) ◽  
pp. 199-206 ◽  
Author(s):  
Yi Zhang ◽  
Loyd R Davies ◽  
Sean M Martin ◽  
Imran M Bawaney ◽  
Garry R Buettner ◽  
...  
Keyword(s):  
Free Radical ◽  
Left Ventricular Function ◽  
Ventricular Function ◽  
Direct Current ◽  
Left Ventricular ◽  
Radical Concentration ◽  
Free Radical Concentration
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