Bioactive Compounds in the Flora of Belarus. 2. Astragalin, an Effective Protector of Catalase from Ultrasonic Inactivation in Aqueous Solutions

The kinetics of catalase decomposition of H2O2 (50 mM) inhibited by the flavonolic glycoside astragalin (1) from the aerial part of Gymnocarpium dryopteris were studied. 1 (0.3-30 M) is a strong inhibitor of the catalase process and was tested as a catalase (CAT) protector from ultrasonic activation at 45°C by treatment of enzyme solutions (1.2 nM) in phosphate buffer (7.5 mM) at pH 5.5 with low-frequency ultrasound (US, 27 kHz) at initial specific power 60 W/cm2. 1 inhibited US-inactivation of CAT according to the rate constants for US-inactivation of CAT in the presence of 1 with and without inhibitor. 1 at concentrations of 1.0 and 20.0 μM decreases US-inactivation up to 22.3 and 19.5% of the initial level. The useful properties and effectiveness of 1 are better than the synthetic inhibitors-antioxidants propylgallate and 4-t-butylpyrocatechin.