Peonidin 3 o glucoside

All chemicals used were of analytical reagent grade. All chromatographic solvents (acetonitrile, acetic acid) were high-performance liquid chromatography (HPLC) grade and were purchased from Sigma-Aldrich (Steinheim, Germany). Delphinidin 3-O-glucoside, cyanidin 3-O-glucoside, peonidin-3-O-glucoside, malvidin 3-O-glucoside, (+)-catechin, (−)-epicatechin, (−)-epicatechin gallate (−)-epigallocatechin, (−)- epigallocatechin gallate, procyanidin B1, procyanidin B2, ferulic acid, caffeic acid and trans-resveratrol were purchased from Extrasynthèse (Lyon, Genay-France). The Folin–Ciocalteu reagent was obtained from Sigma-Aldrich (Steinheim, Germany).

Ethanol absolute was purchased from VWR (Milano, Italy); methanol and 85% w/w phosphoric acid were purchased from Sigma-Aldrich (Steinheim, Germany). LC-MS grade acetonitrile, formic acid, and water were purchased from Merck (Darmstadt, Germany). Standards of cyanidin-3-O-glucoside, cyanidin-3-O-rutinoside, peonidin-3-O-glucoside, peonidin-3-O-rutinoside, quercetin-3-O-rutinoside, quercetin-3-O-glucoside, quercetin-3-O-rhamnoside, p-coumaric acid, ferulic acid, vanillic acid, 3-O-caffeoylquinic acid (neochlorogenic acid), and 5-O-caffeoylquinic acid (chlorogenic acid) were purchased from Extrasynthese (Genay, France) and TransMIT (Giessen, Germany).
Soy lecithin (a mixture of polar phospholipids and glycolipids) and propylene glycol (PG) were purchased from Galeno Srl (Comeana, Prato, Italy).

Formic acid and methanol were purchased from Sigma-Aldrich (Steinheim, Germany). Acetonitrile was purchased from Merck (Darmstadt, Germany). Quercetin-3-O-glucoside, quercetin-3-O-rutinoside, kaempferol-3-O-glucoside, myricetin-3-O-glucoside, isorhamnetin-3-O-glucoside, cyanidin-3-O-glucoside, peonidin-3-O-glucoside, (−)-epicatechin, (+)-catechin, procyanidins, gallic acid were purchased from Extrasynthese (Lyon, France).

Gallic acid, (+)-hydrated catechin, (−)-epigallocatechin, procyanidin B₂, epigallocatechin gallate, (−)-epicatechin, chlorogenic acid, caffeic acid, p-coumaric acid, ferulic acid, Folin–Ciocalteu reagent, sodium carbonate (Na₂CO₃) radical 2,2′-diphenyl-1-picrylyhydrazyl (DPPH), radical 2,2′-azino-bis(3-ethylbenzothiazolin-6-sulfonic) (ABTS), sodium nitrite (NaNO₂), sodium phosphate (Na₃PO₄), aluminum chloride (AlCl₃), hydrochloric acid (HCl), sodium hydroxide (NaOH), absolute ethanol, Dulbecco’s modified Eagle’s medium (DMEM), DMEM without phenol red, phosphate buffer solution (PBS), 2′,7′-dichlorofluorescein diacetate (DCF-DA), hydrogen peroxide (H₂O₂), L-glutamine, penicillin, streptomycin, and Whatman No. 3 filter paper were purchased from Sigma Aldrich (Sigma Chemical Co., St. Louis, MO, USA). Delphinidin-3-O-glucoside (DG), cyanidin-3O-glucoside (CG), petunidin-3O-glucoside (PTG), peonidin-3O-glucoside (POG), and malvidin-3O-glucoside (MG) were purchased from Extrasynthese (Genay, France). HPLC-grade water and acetonitrile were purchased from VWR (Chromasolv, VWR International Srl, Milano, Italy).

The presence of polyphenolic compounds was identified by the LC-PDA-MS method using the Acquity Ultraperformance LC system (Waters Corp., Milford, USA; [9 (link)]). The polyphenol extracts were prepared according to the procedure described by Wojdyło et al. [9 (link)]. The results were evaluated using the MassLynx 4.0 ChromaLynx Application Manager software (Waters Corp., Milford, CT, USA). The quantification of polyphenolic compounds in plum pomace powders was performed by ultra-performance liquid chromatography (UPLC-PDA) (Waters Corp., Milford, USA). Calibration curves (0.05–5 mg∙mL⁻¹; R² = 0.9998) were made from procyanidins B2 and C1, neochlorogenic and chlorogenic acid, quercetin, isorhamnetin and kaempferol-3-O-glucoside, cyanidin-3-O-glucoside, cyanidin-3-O-rutinoside, and peonidin-3-O-glucoside as standards (Extrasynthese, Genay, France). Quercetin and kaempferol derivatives were expressed as quercetin-3-O-glucoside and kaempferol-3-O-glucoside, and coumaroylquinic and caffeoylshikimic acid derivatives as chlorogenic acid. Anthocyanins, flavonol glycosides, phenolic acids and flavan-3-ols were detected at wavelengths of 360, 320, and 280 nm, respectively. The analysis was carried out in duplicate and the results were expressed in mg∙100 g⁻¹ dm.