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The aim of this study was to research the seasonal changes of antioxidant enzyme activity and total antioxidant capacity in leaves of Astragalus onobrychis L. subsp. chlorocarpus (Griseb.) S. Kozuharov et D.K. Pavlova. Leaves of A. onobrychis were collected during the different stages of growth and analyzed for antioxidant enzyme activity: superoxide dismutase, catalase, guaiacol peroxidase, glutathione peroxidase. Quantities of malonyldialdehyde, superoxide radicals, and hydroxyl radicals were measured as well as the content of soluble proteins. Furthermore, total antioxidant capacity was determined by the inhibition of chemiluminescence activity of blood phagocytes by leaf extracts. Stages of vegetation significantly affected the accumulation of superoxide radicals, but there were no significant differences in hydroxyl radical quantity and lipid peroxidation levels during vegetation. Soluble proteins vary greatly between different stages of growth. Seasonal changes were found to have an effect on enzymatic activities. During the spring season, guaiacol peroxidase showed the highest levels. Catalase and glutathione peroxidase increased their activities in summer, while, during the autumn season, superoxide dismutase showed maximum activity. On the basis of chemiluminescence assay, it can be concluded that leaf extract of A. onobrychis possesses a significant antioxidant capacity thus protecting plants during environmental stress. [...]
Content available remote Obtaining and characterizing modified tannins by physical-chemical methods
After oxidation of tannins (Tannins 1–3) extracted from grape seeds, Tanoxil compounds with increased solubility and enhanced antioxidant activities were synthesized. In this research, ABTS+· assay and a chemiluminescence method were used for antioxidant measurement of hydrophilic compounds (Tanoxils 1–3). It was observed that the antioxidant activity (AA, %) is very similar for the three samples, while at the same time AA is quite high (93.16%–96.48%). The percentage of inhibition by ABTS+· is higher for Tanoxil 2 (96.4%) as compared to Tannin 2 compound (14.34%). Moreover, the total content (TCF) of carboxyl and phenolic groups was investigated. TCF values, determined for Tanoxil products, revealed a double (Tanoxil 1) or triple (Tanoxil 2) increase as compared to the value of the TCF of Tannin 1. Tanoxil products represent an interest for future research as they have a high AA (96.4%) and the content of acidic groups is significant (TCF, 0.191 meq g−1).
A simple and selective method for penicillin V potassium (PVK) determination by chemiluminescence (CL) was developed. Oxidation of PVK by alkaline hydrogen peroxide produces CL, which is greatly enhanced by N, N-dimethyl formamide (DMF) and N-cetyl-N,N,N-trimethylammonium bromide (CTMAB). Optimum conditions were established using luminometry. There is a linear relationship between the chemiluminescent peak height and the amount of PVK within the range 0.5–129.5 mg L−1, with a detection limit of 0.2 mg L−1. The coefficient of variation was 1.2% for 40 mg L−1 PVK solution (n = 7). The method is very simple, has high sensitivity and good selectivity, and is usable for process control. It was successfully utilized for the determination of PVK in pharmaceuticals and spiked human urine. [...]
Magnetic fluid applications require stability under demanding conditions. Complete magnetic fluids and their component surfactants and dispersing oils were irradiated. Their subsequent thermal oxidation was characterized by chemiluminescence and DSC. Except for polyisobutylsuccinic anhydride, irradiation sensitized the components toward oxidation. The components were ranked by stability. Complete fluids were more stable than would be predicted from their components suggesting that they may be used for nuclear applications.
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