*2.1. Chemicals*

The reagents used in this study were acetone, ethanol, methanol, hydrochloric acid (37%), and Folin-Ciocâlteu reagent, all of which were purchased from Merck (Darmstadt, Germany).

The standards used for both spectrophotometric and LC-MS/MS analysis were: quercetin (≥95%), hyperoside (quercetin 3-D-galactoside, ≥97%), isoquercitrin (quercetin 3-D-glucoside, ≥98%), quercitrin (quercetin 3-rhamonoside, ≥78%), (+)-catechin (≥96%), (−)-epicatechin (≥90%), vanillic acid (≥97%), syringic acid (≥95%), protocatechuic acid (3,4-dihydroxybenzoic acid, ≥97%), campesterol (~65%), ergosterol (≥95%), and stigmasterol (~95%) purchased from Sigma-Aldrich, gallic acid (≥98%) purchased from Merck (Darmstadt, Germany), and beta-sitosterol (≥80%) purchased from Carl Roth (Karlsruhe, Germany).
