Peltatoside

The leaves of N. nucifera Gaertn. were purchased from Paiho Farmers’ Association Organization in Tainan County, Taiwan. Formic acid (reagent grade, 96%) was purchased from Tedia (Fairfield, OH, USA). Acetonitrile and methanol (high-performance liquid chromatography-grade, Darmstadt, Germany). The liquid chromatography grade polyphenol standards including isoquercitrin, peltatoside, and miquelianin were obtained from Extrasynthese (Genay, France). AAF, bovine serum albumin, dithiothreitol, ethylenediaminetetraacetic acid, formaldehyde, N-(2-hydroxyethyl) piperazine-N’-ethanesulfonic acid, phenylmethylsulfonyl fluoride, and sodium phosphate were purchased from Sigma (St. Louis, MO, USA). Antibodies against catalase, glutathion peroxidase (GPx), superoxide dismutase 1 (SOD-1), and nuclear factor erythroid 2-related factor 2 (Nrf2) were purchased from Cell Signaling Technology (Beverly, MA, USA), and β-actin as internal control was purchased from Santa Cruz Biotechnology (Santa Cruz, CA, USA). Peroxidase-conjugated antibodies against rabbit IgG or mouse IgG were purchased from Sigma.

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).