Aesculin

The sugar standards (glucose, fructose, sucrose, arabinose, isomaltose, raffinose, maltose, and panose) were purchased from Supelco/Sigma–Aldrich (St. Louis, MI, USA). Standards for organic acids (quinic acid, shikimic acid, galacturonic acid, fumaric acid, malic acid, maleic acid and citric acid) and polyols (sorbitol and mannitol) were purchased from Supelco/Sigma–Aldrich (St. Louis, MI, USA), while sodium acetate trihydrate and 50% sodium hydroxide solution were from Sigma–Aldrich (St. Louis, MI, USA). All aqueous solutions were prepared with ultrapure water (0.055 µS/cm) obtained using the Thermo Fisher (Waltham, MA, USA) TKA MicroPure water purification system. Polyphenol standards (gallic acid, chlorogenic acid, catechin, caffeic acid, aesculin, rutin, p-coumaric acid, hyperoside; isorhamnetin-3-O-rutinoside, isorhamnetin-3-O-glucoside, kaempferol-3-O-glucoside, quercetin-3-O-rhamnoside, ellagic acid, quercetin, isorhamnetin) were purchased from Sigma–Aldrich (St. Louis, MI, USA).

Acetonitrile and formic acid (both MS grade), methanol (high-performance liquid chromatography, HPLC grade), sodium hydroxide, sodium acetate, and hydrochloric acid were purchased from Merck (Darmstadt, Germany). Ultra-pure water (Thermofisher TKA MicroPure water purification system, 0.055 µS/cm; Bremen Germany) was used to prepare standard solutions and blanks. The solid phase extraction (SPE) cartridges used to concentrate the samples were Strata C18–E (500 mg/3 mL) obtained from Phenomenex (Cluster d.o.o., Belgrade, Serbia). Syringe filters (25 mm, nylon membrane, 0.45 µm) were purchased from Psi lab d.o.o. (Belgrade, Serbia). Filter paper (Whatman No.1) was supplied by Merck.
Phenolic standards (protocatechuic acid, p-hydroxybenzoic acid, vanillic acid, syringic acid, ellagic acid, chlorogenic acid, caffeic acid, p-coumaric acid, ferulic acid, sinapic acid, cinnamic acid, rutin, hyperoside, cynaroside, apiin, naringin, astragalin, catechin, luteolin, apigenin, naringenin, kaempferol, aesculin, phloridzin, coniferyl aldehyde, and aesculetin) were supplied by Sigma Aldrich (Steinheim, Germany).
Sugar standards (trehalose, arabinose, glucose, fructose, sucrose, isomaltotriose, turanose maltose, and maltotriose) were purchased from Tokyo Chemical Industry (TCI, Europe, Belgium). Standard of sorbitol was obtained from Sigma Aldrich (Steinheim, Germany).

Acetonitrile and acetic acid (both of MS grade), methanol (HPLC grade), Folin–Ciocalteu reagent, hydrochloric acid, sodium hypochlorite, and sodium carbonate were purchased from Merck (Darmstadt, Germany). Ultrapure water (Thermofisher Scientific, Bremen, Germany) was used to prepare standard solutions and blanks. Syringe filters (25 mm, nylon membrane, 0.45 μm) were purchased from Supelco (Bellefonte, PA, USA). Analytical standards of phenolic compounds (gallic acid, protocatechuic acid, gentisic acid, p-hydroxybenzoic acid, p-hydroxyphenylacetic acid, caffeic acid, vanillic acid, syringic acid, p-coumaric acid, ferulic acid, aesculin, aesculetin, polydatin, trans-resveratrol, catechin, isoquercetin, myricetin, luteolin, and naringenin) were purchased from Sigma-Aldrich (Steinheim, Germany).