Naringenin

The phenolic standards, rutin (≥ 95% purity, CAS No. 153-18-4), epigallocatechin-3-O-gallate (EGCG) (≥ 95% purity, CAS No. 989-51-5), (+)-naringenin (≥ 98% purity, CAS No. 67604-48-2), naringin (≥ 95% purity, CAS No. 10236-47-2), apigenin (≥ 94% purity, CAS No. 520-36-5), daidzein (≥ 98% purity, CAS No. 486-66-8), phloretin (≥ 98% purity, CAS No. 60-82-2) were purchased from Biosynth® CarboSynth (Bratislava, Slovakia); whereas quercetin (≥ 95% purity, CAS No. 117-39-5), ellagic acid (≥ 96% purity, CAS No. 476-66-4) and phloroglucinol (≥99% purity, CAS No. 108-73-6) - were purchased from Sigma-Aldrich (Madrid, Spain). HPLC-grade methanol, water, and acetonitrile were supplied by Fisher Scientific Chemicals. The enzymes α-amylase (A1031), pepsin from porcine stomach mucosa (P7012), pancreatin from porcine pancreas (P7545), and bile salts (B863) were purchased from Sigma-Aldrich (Taufkirchen, Germany). The rabbit gastric extract (RGE15) with gastric lipase activity was purchased from Lipolytech (Marseille, France). The ethanol was purchased from Merck (Algés, Portugal). A dialysis membrane with a molecular pore size of 3 kDa was purchased from Spectra/Pro (Spectrum Lab, Breda, Netherlands).

Methanol (Chromosolv^TM for HPLC, ≥99.9%) and acetonitrile (UHPLC supergradient ACS quality) were obtained from PanReac AppliChem (Barcelona, Spain), formic acid (≥98%) from Sigma-Aldrich (St Louis, MO, USA), and hydrochloric acid (37%) from Fisher Chemical (Geel, Belgium). Water was purified by employing an Elix 3 system coupled to a Milli-Q instrument from Millipore Corporation (Bedford, MA, USA). The water was filtered with a 0.22 µm nylon membrane filter integrated into the Milli-Q instrument.
All the polyphenolic and phenolic acid compounds used in this work were of analytical grade and were obtained from Sigma-Aldrich, with the exception of hesperidin obtained from Glentham Life Sciences (Lorsham, United Kingdom), astilbin and caftaric acid from Biopurity Phytochemicals Ltd. (Chengdu, Sichuan, China), trans-coumaric acid and procyanidin C1 from Phytolab (Vestenbergsgreuth, Germany), diosmin, hesperetin, and catechol from AlfaAesar Chemicals (ThermoFisher, Kandel, Germany), naringin, naringenin, and epigallocatechin from Biosynth-Carbosynth (Berkshire, United Kingdom), procyanidins B2 and A2 from Extrasynthese (Genay, France), pinocembrin from Fisher Scientific (Madrid, Spain), tricetin and galangin from Cymit Quimica S.L. (Barcelona, Spain), and chrysin and pinobanksin from Merck (Darmstadt, Germany).