Protective action of substituted polyphenols on catalase subjected to ultrasonic inactivation in solutions

The kinetics of the inhibition of the catalase-catalyzed decomposition of 50 mM H 2 O 2 by propyl gallate, its polydisulfide, astragalin (flavonol glycoside) extracted from the aboveground part of Gymnocarpium dryopteris, and derivatives of six tert-butyl-substituted catechols was studied in a 10 mM phosphate buffer at 30°C and pH 5.5 or 7.4. The effect of these polyphenols (0.3-30.0 μM) on the catalase process was characterized by the degree of inhibition. Five substituted catechols with the lowest inhibition effect were tested as protectors of catalase (1.2 nM) from ultrasound inactivation in a 7.5 mM phosphate buffer (pH 5.5 or 7.4) by low-frequency (27 kHz, 60 W/cm 2 ) and high-frequency (2.64 MHz, 1.0 W/cm 2 ) ultrasound. The hindering effect of the polyphenols on the ultrasound inactivation was quantitatively characterized. According to a combination of useful properties, the most effective protectors of catalase from ultrasound inactivation are 4-tert-butylcatechol, 2-(4,6-di-tert-butyl-2,3-dihydroxyphenylsulfinyl) acetic acid, and astragalin, which, taken in concentrations 1.0-30.0 μM, decrease the inactivation rate to 14.8-34.0% of its initial value.