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

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.

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

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.

EPR examination of free radicals thermally formed in vaselinum flavum

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.

Protective effect of CV247 against cisplatin nephrotoxicity in rats

CV247 (CV), an aqueous mixture of copper (Cu) and manganese (Mn) gluconates, vitamin C and sodium salicylate increased the antitumour effects of cisplatin (CDPP; cis-diamminedichloroplatinum) in vitro. We hypothesized that the antioxidant and cyclooxygenase-2 (COX-2; prostaglandin-endoperoxide synthase 2) inhibitory components of CV can protect the kidneys from CDPP nephrotoxicity in rats. CDPP (6.5 mg/kg, intraperitoneally) slightly elevated serum creatinine (Crea) and blood urea nitrogen (BUN) 12 days after treatment. Kidney histology demonstrated extensive tubular epithelial damage and COX-2 immunoreactivity increased 14 days after treatment. A large amount of platinum (Pt) accumulated in the kidney of CDPP-treated rats. Furthermore, CDPP decreased renal iron (Fe), molybdenum (Mo), zinc (Zn), Cu and Mn concentrations and increased plasma Fe and Cu concentrations. CDPP elevated plasma free radical concentration. Treatment with CV alone for 14 days (twice 3 ml/kg/day orally) did not influence these parameters. Chronic CV administration after CDPP reduced renal histological damage and slightly decreased COX-2 immunoreactivity, while failed to prevent the increase in Crea and BUN levels. Blood free radical concentration was reduced, that is, CV improved redox homeostasis. CV restored plasma Fe and renal Fe, Mo and Zn, while decreased Pt and elevated Cu and Mn concentrations in the kidney. Besides the known synergistic antitumour effects with CDPP, CV partially protected the kidneys from CDPP nephrotoxicity probably through its antioxidant effect.

Novel Bioadhesives for Restorative Dentistry

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

An 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.