Eriodyctiol

Rosmarinic acid and the 7-O-glucoside derivatives of apigenin, luteolin, eriodyctiol, quinic acid, caffeic acid, 5-O-caffeoylquinic acid, 4-O-hydroxybenzoic acid, salvianolic acid B, caffeic acid, ferulic acid, and 4-O-coumaric acid were obtained from Extrasynthese (Genay Cedex, France). Trolox, sulforhodamine B (SRB), DPPH (2,2-diphenyl-1-picrylhydrazyl) radical, acetic acid, ellipticine, trypan blue, trichloroacetic acid (TCA), Tris, lipopolysaccharide (LPS), carnosol, nisin, ascorbic acid, and butylated hydroxyanisole (BHA) were obtained from Sigma Chemical Co (St Louis, MO, USA). Fetal bovine serum (FBS), L-glutamine, trypsin-ethylenediaminetetraacetic acid (EDTA), penicillin/streptomycin solution (100 U/mL and 100 mg/mL, respectively), Roswell Park Memorial Institute (RPMI) 1640 Medium and Dulbecco’s Modified Eagle Medium (DMEM) were from Hyclone (Logan, Utah, UT, USA). The Griess reagent system was purchased from Promega Corporation (Madison, WI, USA). Mueller-Hinton agar was from VWR (Prolabo Chemicals, USA); formic acid and ethanol was from Panreac (Barcelona, Spain). n-Hexane, methanol, and acetonitrile were purchased from Lab-Scan (Lisbon, Portugal). Purified water was obtained from a Direct-Q^® water purification system (Merck Life Science, Darmstadt, Germany).

Isoxanthohumol (≥99%) was purchased from Sigma Aldrich GmbH, while xanthohumol (≥98%) and 8-prenylnaringenin (≥ 98%) were purchased from Enzo Life Sciences, Farmingdale, New York. Eriodyctiol (≥ 99%) and 3,4,2’,4’,6’-pentahydroxychalcone(≥99%) were purchased from Extrasynthese Lyon, France. Stock solutions of all reference standards were prepared in HPLC grade methanol (J. T. Baker, Deventer, The Netherlands). The same solvent was used for the extraction. Acetonitrile (ACN) was used as the organic part of the mobile phase (LC-MS grade, J. T. Baker, Deventer, Netherlands). Both formic acid (FA) used for SPE (>98% purity) and FA (LC-MS grade) used as a mobile phase modifier were purchased from Sigma Aldrich (Darmstadt, Germany).MilliQ (18.2 MΩ·cm) water was obtained using a Direct-Q^®Water Purification System (Merck, Darmstadt, Germany). Strata-X 33 µm polymeric reversed phase cartridges (60 mg/3 mL) were purchased from Phenomenex (Torrance, CA, USA). Before injection into the LC-MS system, the samples were filtered through 0.2 µm regenerated cellulose (RC) membrane syringe filters (Phenomenex, Torrance, CA, USA). Hops and beer samples were freeze-dried in a GAMMA 1-16 LSCPlus freeze dryer (Martin Christ Gefrierungstrochnungsanlagen GmbH, Osterode am Harz, Germany).