Procyanidin c1

HPLC-grade methanol and acetonitrile were obtained from Fisher Scientific (Pittsburgh, PA, USA). The chemical standards for quercetin-3-O-galactoside (≥90%), catechin (≥98%), and phloridzin (≥99%) were purchased from Sigma-Aldrich (St. Louis, MO, USA). Procyanidin B1 (>95%) and procyanidin B2 (>95%) were purchased from Solarbio (Beijing, China). Procyanidin C1 (>95%) and quercetin-3-O-glucoside (>98%) were purchased from Shanghai Yuanye Biotechnology Co., Ltd (Shanghai, China). Folin-Ciocalteu reagent (2 mol/L), 4-dimethylaminocinnamaldehyde (DMAC), dimethyl sulfoxide (DMSO), alpha-glucosidase (EC 3.2.1.20), and 4-nitrophenyl-α-D-glucopyranoside (PNPG) were purchased from Sigma-Aldrich (St. Louis, MO, USA). The mass spectrometry LockSpray calibration solution was leucine-encephalin and it was commercially available from Waters Corporation (ESI⁻: 554.2615, ESI⁺: 556.2771, Waters, UK). Double-distilled water (ddH₂O) was used in all experiments and samples for UPLC-Q-TOF/MS were filtered through a 0.22 μm membrane before injection. All the other reagents were of analytical grade bought from Sinopharm Chemical Reagent Co., Ltd. (Shanghai, China).

Chromatographically pure acetonitrile and acetic acid was purchased from Thermo Fisher (Waltham, MA, USA). Catechins (C), epicatechin (EC), gallocatechin (GC), epigallocatechin (EGC), epigallocatechin gallate (ECG), gallocatechin gallate (GCG), epigallocatechin-3-O-gallate (EGCG), procyanidin B1, procyanidin C1, kaempferitrin, rutin, isoquercetin, myricetin-3-O-galactoside, myricetin-3-O-rutinoside, galloylglucose, gallic acid, cinnamic acid, chlorogenic acid, shikimic acid, p-coumaric acid, quinic acid, pyrogallic acid, theogallin, strictinin, theanine, theobromine, ethyl gallate, tannic acid, caffeine, L-sodium glutamate, and D-glucose were purchased from Yuanye (Shanghai, China). Quercetin, myricetin, kaempferol, and kaempferol-3-O-glucoside were purchased from Shanghai Zzstandard (Shanghai, China). Amino acid mixture standard reagent, borate buffer solution, o-phthalaldehyde (OPA), and 9-fluorene methyl chloroformate (FMOC) were purchased from Agilent Technology (Santa Clara, CA, USA). n-Hexane was purchased from Thermo Fisher (Waltham, MA, USA). 2-Methyl-3-heptanone and n-alkanes (C₇–C₃₀) were purchased from Sigma (St. Louis, MO, USA).