Ethanol extracts from Bergenia crassifolia (L.) Fritsch. green leaves exhibit antioxidant properties. The most significant activity has been observed for 70% ethanol extract, which is a typical acceptor of peroxy radicals. Fractionation of the active extract yielded chloroform and ethyl acetate fractions, which also showed a pronounced antioxidant action. Phenolic compounds (hydroquinone, quercetin, dihydroquercetin, rutin, gallic acid, esculetin) also exhibited significant antioxidant activity comparable with that of ionol. 620 0091-150X/06/4011-0620
A model of formation of asphalt-resin-wax deposits (ARWD) based on the concept of the spin nature of dispersions in petroleum-like systems is proposed. Dissolution of ARWD on addition of used industriallube oil is examined with respect to transformation of the structure, whose dynamics is complex. Paramagnetism which changes in time passes through extrema. A slight increase in the concentration of paramagnetic centers (PMC) is observed after one day, and further recombination of the centers with formation of molecular products is observed after two days. The change in the structure of the associates in time is confirmed by the change in the antioxidant properties and viscosity of the composition.The inhomogeneous compositions of ARWD as a function of wells and fields and the effect of a multitude of factors on their formation, including the structural group composition and physicochemical properties of the crude, temperature, and contact with the surface of pipes or tanks, have made it necessary to develop many different methods for controlling these deposits: mechanical, thermal, physical, chemical, microbiological.However, all of these methods are not very effective or economical and have a temporary effect. A theoretical concept based on the principles of construction of colloidal particles during formation of deposits and the mechanisms of structural changes during their dissolution is required for successfully solving this problem.Our electron paramagnetic resonance (EPR) studies of ARWD revealed one inherent property outside of the dependence on the factors described above -high paramagnetism which sometimes exceeded Avogadro's number. This made it possible to use the concept of the build-up and structure of the deposits examined below [1-4].The EPR spectra were recorded on a RADIOPAN SE/X-2544 EPR spectrometer with ruby rods built into the resonator as internal standard [1]. The standard rubies were calibrated with the signal of vanadyl acetylacetonate carefully dispersed in nonparamagnetic Vaseline (10 19 spin/cm 3 concentration of the mixture). Quartz ampuls with an outer diameter of 4 mm were used in the study. The EPR spectra of some ARWD from active wellheads are shown in Fig. 1. The paramagnetism of these deposits is composed of the paramagnetism of multispin metals -the broad unresolved line, and the paramagnetism of carbon compounds -the narrow line. The first and third peaks in the spectrum belong to the internal standard, in the concentration of 1.09⋅10 18 spin/cm 3 .
UDC 547.972The solubility and antioxidant activity of the bioflavonoid quercetin was increased from its mechanochemically prepared solid composites with metal carbonates and carbohydrate compounds.Keywords: quercetin, mechanical treatment, arabinogalactan, basic magnesium carbonate, bioavailability, solubility, activity.3,5,7,3c,4c-Pentahydroxyflavone (quercetin, 1) was formerly known as vitamin P. Preparations of quercetin reduce the permeability of capillaries and exhibit anti-inflammatory effects, radioprotector activity, and anti-ulcer action associated with the use of anti-inflammatory agents [1][2][3][4]. The development of new drugs and biologically active additives (BAAs) with increased water solubility, bioavailability, and effectiveness is interesting because quercetin is practically insoluble in water. The goal of our work was to prepare water-soluble solid powder composites based on quercetin by forming water-soluble complexes and salt forms of quercetin with MgCO 3 and CaCO 3 [7-9]. Table 1 presents solubility measurements for 1 from the resulting composites. It can be seen that the solubility of 1 from the composites increased, the exceptions being samples 1 and 13. The dissolution of quercetin from sample 1 took a long time (>>1 h). Thus, its equilibrium solution concentration was not reached under the experimental conditions. The polysaccharide chitosan, which is poorly soluble in water, was used in sample 13. The principal fraction of 1 was found bound to the solid precipitate and not in solution upon forming adducts of chitosan and 1. This explained the results. The increased solubility in composites 2, 3, 5-10, and 12 was obviously achieved by forming water-soluble intermolecular complexes of quercetin and the carbohydrates through the reported mechanism [5,6]. The strength of the intermolecular complexation and, as a result, the water solubility of quercetin, increased with the duration of mechanical treatment and the production of a more homogeneous dispersion. The reason for the increased solubility in composites 4 and 11 was apparently the formation of water-soluble salt forms of 1 by the reported mechanism [5, 10, 11]. Thus, both pathways for increasing the solubility were clearly effective.We studied several physicochemical characteristics such as morphological changes of the powder particles, DSC thermograms, and x-ray diffraction patterns of the produced powdered solid dispersions. Figure 1 (a, b, c) shows photomicrographs of powdered arabinogalactan (Fig. 1a), quercetin (Fig. 1b), and a watersoluble dispersion of quercetin-arabinogalactan (1:10) composite treated mechanically for 4 h (Fig. 1c). Aggregates of ground particles formed after mechanical treatment. Figure 1d, 1e, and 1f shows photomicrographs of powdered basic magnesium carbonate, quercetin, and water-soluble disperse quercetin-magnesium carbonate (6:4) treated mechanically for 1.5 h. An analysis of these photographs showed that aggregates of ground particles also formed after mechanical treatment.
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