Trifluoroacetic acid tfa

The reagents were used as received. Griseofulvin was purchased from Tokyo Chemical Industry Co., Ltd. (Tokyo, Japan). The purity of the Griseofulvin was guaranteed to be ≥97.0%. Hydrocortisone, methanol, polyvinylpyrrolidone K30 (PVP K30), buffer components (sodium dihydrogen phosphate dihydrate (NaH₂PO₄⸱2H₂O), sodium hydroxide (NaOH), sodium chloride (NaCl)), heptane, sorbitan monooleate, acetonitrile (MeCN) and trifluoroacetic acid (TFA) were purchased from FUJI FILM Wako Pure Chemical Co. (Osaka, Japan). Hydrocortisone and PVP K30 were Wako special grade. The purity of the Hydrocortisone was guaranteed to be ≥97.0%. The NaH₂PO₄⸱2H₂O, NaOH, NaCl and heptane were guaranteed reagents. The purity of the NaH₂PO₄⸱2H₂O, NaOH, NaCl and heptane was guaranteed to be 99.0–102.0%, ≥97.0%, ≥99.5% and ≥99.0%. The methanol, MeCN and TFA were for high-performance liquid chromatography (HPLC). The purity of the methanol, MeCN and TFA was guaranteed to be ≥99.7%, ≥99.9% and ≥99.8%. Dioctyl sulfosuccinate (AOT) and sodium lauryl sulfate (SLS) were purchased from Sigma–Aldrich (St. Louis, MO, USA). The purity of the AOT and SLS was guaranteed to be ≥97% and ≥98.0%. Gastrointestinal tract (GIT) lipids and the acceptor sink buffer (ASB) were purchased from Pion Inc. (Billerica, MA, USA).

Protease inhibitor was obtained from Merck (Darmstadt, Germany). Triethylammonium bicarbonate (TEABC), iron (III) chloride (FeCl₃), acetic acid, formic acid, HPLC-grade acetonitrile (ACN), sodium deoxycholate (SDC), sodium lauroyl sarcosinate (SLS), heavy and light (¹³CD₂O or ¹²CH₂O) formaldehyde were purchased from Sigma Aldrich (St Louis, MO, USA). The BCA protein assay kit was obtained from Pierce (Rockford, IL, USA). Trifluoroacetic acid (TFA) and lysyl endopeptidase were purchased from WAKO (Osaka, Japan). Modified sequencing-grade trypsin was purchased from Promega (Madison, WI, USA). Ni-NTA silica resin was purchased from Qiagen (Hilden, Germany). SDB-XC Empore disks were obtained from 3M (St Paul, MN, USA). Water was obtained from a Millipore Milli-Q system (Bedford, MA, USA).

Chemicals used in this study were the same as previously reported^{14 (link)}. Briefly, 3-O-glucosyldelphinidin (Dp3G; 1) was purified from the seed coat of the scarlet bean, Phaseolus coccineus, and the copigments 5-O-caffeoylquinic acid (2) and 5-O-p-coumaroylquinic acid (3) were synthesized^{13 (link)}. 3-O-Caffeoylquinic acid (4) and trifluoroacetic acid (TFA) were purchased form FUJIFILM Wako Pure Chemical Corporation (Osaka, Japan), and KCl and AlCl₃·12H₂O was purchased from KANTO KAGAKU (Tokyo, Japan).