Standard of trans piceid

Formic acid, HPLC grade methanol, acetone, hydrochloric acid, trifluoroacetic acid, ammonium formiate, L-ascorbic acid, and phloroglucinol were purchased from Sigma Aldrich (St Louis, MO, USA). Deionized water was obtained from a Milli-Q purification system (Millipore, Molsheim, France). Standards of (+)-catechin, (–)-epicatechin, (–)-epicatechin 3-O-gallate, reduced L-glutathione, oxidized L-glutathione, piceatannol, p-coumaric acid, protocatechuic acid, syringic acid, trans-caftaric acid, and trans-resveratrol were purchased from Sigma-Aldrich (St Louis, MO, USA). Standards of (–)-epigallocatechin, gallic acid, hydroxytyrosol, malvidin 3-O-glucoside chloride, malvidin 3,5-di-O-glucoside chloride, procyanidin B2, quercetin 3-O-glucuronide, and taxifolin were purchased from Extrasynthese (Geney, France). Standards of caffeic acid, ferulic acid, and vanillic acid were purchased from Fluka (Buchs, Switzerland). Standards of 1-O-Galloyl-β-D-glucose and quercetin 3-O-glucoside were purchased from PlantMetaChem, Transmit GmbH (Gießen, Germany). Standard of trans-piceid was purchased from Selleckchem (Houston, TX, USA).

Formic acid and HPLC grade methanol were purchased from VWR Prolabo (Fontenay-sous-Bois, France). Deionized water was obtained from a Milli-Q purification system (Millipore, Molsheim, France). Standard of trans-piceid was purchased from Selleckchem (Houston, TX, USA). Standards of caffeic acid, vanillic acid, gallic acid and ferulic acid were purchased from Fluka (Buchs, Switzerland). Standards of syringic acid, p-coumaric acid, protocatechuic acid, ethyl protocatechuate, tyrosol, tryptophol, tryptophan, trans-resveratrol, quercetin, catechin, epicatechin, epicatechin 3-gallate, taxifolin, oxidized and reduced glutathione were purchased from Sigma-Aldrich (St. Louis, MO, USA), as well as hydrochloric acid, phloroglucinol, L-ascorbic acid, and ammonium formiate. Standards of ethyl gallate, ethyl caffeate, tyrosine, hydroxytyrosol, epigallocatechin, malvidin 3-O-glucoside chloride, and malvidin 3,5-diglucoside chloride were purchased from Extrasynthese (Geney, France). Standards of trans-caftaric acid, quercetin glucoside and procyanidin dimers B1, B2, B3, B4, and trimer C1 were purchased from Phytolab (Vestenbergsgreuth, Germany).