Procyanidin b2

BSA (purity > 96 %) was acquired from YuanYe Biotechnology Co., Ltd. (Shanghai, China). d-fructose, AG, methylglyoxal (MGO, 40 % v/v) and glyoxal (GO, 40 % v/v) were obtained from Solarbio Technology Co., Ltd. (Beijing, China). Cyanidin-3-O-arabinoside, cyanidin-3-O-galactoside and procyanidin B2 were purchased from ChemFaces Biochemical Co., Ltd. (Wuhan, China). o-Phenylenediamine (ΟPD), 2,2-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS), and other chemical reagents were bought from Sinopharm Chemical Reagent Co. Ltd. (Shanghai, China), analytical grade.

Formic acid and methanol (LC-MS grade) were purchased from TIC (Tokyo, Japan) and Merck (Darmstadt, Germany), respectively. Deionized ultrapure water was obtained from Millipore (Bedford, MA, USA). Flavanols of epigallocatechin gallate (EGCG), epigallocatechin (EGC), epicatechin gallate (ECG), epicatechin (EC), gallocatechin gallate (GCG), gallocatechin (GC), catechin gallate (CG), and catechin (C), 1,3,7-trimethyluric acid, kaempferol-3-glucoside, quercetin-3-glucoside, quercetin-3-galactoside, myricetin 3-galactoside, naringenin, valine, tryptophan, arginine, proline, theogallin, chlorogenic acid and 5-methoxysalicylic acid were obtained from Sigma (St. Louis, MO, USA). Theacrine, theobromine and caffeine were purchased from Yuanye (Shanghai, China). Procyanidin B1, procyanidin B2 and procyanidin B3 were gained from ChemFaces (Wuhan, Hubei, China). Epiafzelechin and epiafzelechin 3-gallate were obtained from Mreda (Beijing, China) and Asiabio (Basel, Switzerland), respectively. epigallocatechin-3-O-(3″-O-methyl)-gallate (EGCG3″Me) and epicatechin-3-O-(3″-O-methyl)-gallate (ECG3″Me) were purchased from Nagara Science Co., Ltd. (Gifu, Japan). Phenylethyl primeveroside and benzyl primeveroside were synthesized by staff at the National Glycoengineering Research Center, Shandong University, Jinan, China (Li et al., 2019 (link)).