Gallocatechin

All chemicals were at least of analytical grade. Toluene, 1-propanol, formic acid, acetic acid, hydrochloric acid (37%) and 4-dimethylaminocinnamaldehyde (DMACA) were from Merck (Darmstadt, Germany). Ethanol, acetone, as well as HPLC grade acetonitrile and mEthanol were purchased from Sigma-Aldrich (St. Louis, MO, USA). LC-MS grade acetonitrile and mEthanol used for MS analyses were from Fluka (Buchs, Switzerland). MilliQ 18.2 MΩ water (Millipore, Bedford, MA, USA) was also used.
Standards of (−)-epicatechin gallate, (−)-epigallocatechin, (−)-epigallocatechin gallate, (−)-catechin gallate, (−)-gallocatechin, (−)-gallocatechin gallate, procyanidin B1, procyanidin B2, procyanidin B3 and procyanidin C1 were obtained from Extrasynthèse (Genay, France), while (−)-epicatechin was from Sigma-Aldrich and (+)-catechin from Carl Roth (Karlsruhe, Germany).

All chemicals were at least of analytical grade. Acetic acid, formic acid, hydrochloric acid (37%), toluene, 1-propanol, and 4-dimethylaminocinnamaldehyde (DMACA) were from Merck (Darmstadt, Germany). Acetone, ethanol as well as HPLC grade acetonitrile and methanol were purchased from Sigma-Aldrich (St. Louis, MO, USA). LC–MS grade acetonitrile and methanol used for MS analyses were from Fluka (Buchs, Switzerland). MilliQ 18.2 MΩ water (Millipore, Bedford, MA, USA) was also used.
Standard of (−)-epicatechin was obtained from Sigma-Aldrich and (+)-catechin from Carl Roth (Karlsruhe, Germany). Standards of procyanidin B1, procyanidin B2, procyanidin B3, procyanidin C1, (−)-catechin gallate, (−)-gallocatechin, (−)-gallocatechin gallate, (−)-epicatechin gallate, (−)-epigallocatechin and (−)-epigallocatechin gallate were obtained from Extrasynthèse (Genay, France).

MEM with Earle's salts, DMEM, fetal bovine serum (FBS), trypsin‐EDTA, and antibiotics were purchased from Biochrom GmbH (Berlin, Germany). Entero‐STIM Intestinal Epithelium Differentiation Medium and MITO+ Serum Extender were purchased from Corning (Wiesbaden, Germany). Hesperetin, peltatoside, hyperoside, kaempferol, ellagic acid, isoquercitrin, quercitrin, phloretin, (−)‐epicatechin, epigallocatechin, epicatechin gallate, procyanidin B1, procyanidin B2, epigallocatechin gallate, gallocatechin, and morine were obtained from Extrasynthese (Genay Cedex, France). Phloridzin, chlorogenic acid, caffeic acid, quercetin, (+)‐catechin, gallic acid, 2‐mercaptoethanol, NaCl, MgSO₄, KCl, CaCl₂, HEPES, and xylitol were purchased from Sigma‐Aldrich (Schnelldorf, Germany). Guaijaverin and avicularin were obtained from Glentham Life Sciences (Corsham, United Kingdom). Purified and concentrated GLE (cGLE) was provided by Belan GmbH (Wels, Austria).30 Guava fruit puree for preparation of fruit extracts was obtained from Tradework BV (Rotterdam, The Netherlands), commercially available GLE and apple extract (AE) were purchased from Pfannenschmidt (Hamburg, Germany). Transwell inserts (12 mm, collagen‐treated, 0.4 μm pore size) and 12‐well plates were obtained from Corning (Wiesbaden, Germany).