2.2. Hydrogen Peroxide Scavenging Activity

The hydrogen peroxide scavenging activity of polyphenols was estimated by luminol-dependent chemiluminescence (LCL) as described previously [31]. Briefly, the reaction mixtures contained NaH₂PO₄/NaOH buffer (20 mM, pH 7.4), luminol (100 µM), horseradish peroxidase (1.25 U), hydrogen peroxide (10 µM), and polyphenols at different concentrations (0.25–40.0 µM). Hydrogen peroxide was added to the solutions immediately prior to the registration of the signal. LCL was recorded in 96-well plates (Greiner, Kremsmunster, Austria) using a multi-plate reader (Infinite F200 Tecan, Grodig, Austria) until it returned to the baseline. The reduction in LCL signal intensity in the presence of polyphenols was estimated using the following formula: ∫LCL = (∫polyphenol/∫control) × 100%, where ∫LCL is the integral LCL, %; ∫polyphenol is the integral LCL in the presence of polyphenols; ∫control is the integral LCL without the addition of polyphenols. Measurements were carried out at 37 °C.