Methanol and acetonitrile

Formic acid, 2,2‐azinobis (3‐ethylbenzothiazoline‐6‐sulfonic acid) diammonium salt (ABTS), and 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) were obtained from Sigma‐Aldrich Chemical Co. (St. Louis, MO, USA). Trolox (6‐hydroxy‐2,5,7,8‐tetramethylchromane‐2‐carboxylic acid) was purchased from Acros Organics (Morris Plains, NJ, USA). Fluorescein disodium was purchased from Chemical Industrial of East China Normal University (Shanghai, China). Gallic acid, rutin, catechin, 2,2’‐azobis(2‐methylpropionamide)‐dihydrochloride (AAPH), and Folin‐Ciocalteu's reagent were obtained from J&K Chemical Ltd. (Beijing, China). The HPLC standards, including 3‐caffeoylquinic acid, 4‐caffeoylquinic acid, 5‐caffeoylquinic acid, 3,5‐dicaffeoylquinic acid, 4,5‐dicaffeoylquinic acid, kaempferol‐3‐O‐glucoside, quercetin, quercetin‐3‐O‐galactoside, quercetin‐3‐O‐rutinoside, and quercetin‐3‐O‐arabinoside, were bought from Yuanye Chemical Ltd. (Shanghai, China). Methanol and acetonitrile (chromatographic grade) were obtained from TEDIA (Ohio, USA). The purity of the standards and solvents used for HPLC was verified > 95%. All the other chemicals and reagents were of analytical grade.

Blank, hemolyzed and lipemic plasmas were kindly donated by Centro de Hematologia e Hemoterapia do Paraná (Hemepar, Curitiba, Brazil). Samples of guaco syrup (same brand and lot) containing 0.295 mg/mL of COU, 0.018 mg/mL of OCA and 0.148 mg/mL of KAU, were obtained from local markets (Curitiba, Brazil). The amounts of each compound were determined by HPLC-MS/MS [24 (link)]. Methanol and acetonitrile (HPLC grade) were purchased from Tedia (Fairfield, USA), and formic acid (88%) was obtained from J. T. Baker Chemicals B.V. (Deventer, the Netherlands). Ammonium formate (97%) was purchased from Acros Organics (New Jersey, USA). Ultrapure water was obtained using a Milli-Q purification system from Millipore Corporation (Bedford, USA). tert-butyl methyl ether (99.8%) and standards of COU (99.0%), 7-HCOU (99.8%) and OCA (97.0%) and internal standards (IS) of 6-methylcoumarin (99.0%), isoferulic acid (98.0%) and prednisone (99.0%) were purchased from Sigma Aldrich (St. Louis, USA). KAU was isolated from M. lanuginosa DC, was purified, was identified (IR, GC/MS, 1H, and 13C NMR, S1 Fig.) [26 ], and was kindly donated by Dr. Obdulio Gomes Miguel of the Phytochemical Laboratory of Universidade Federal do Paraná.

For the extraction of carotenoids and vitamin E, the following analytical-grade reagents were used: acetone and petroleum ether (Vetec, Brazil). The following HPLC-grade reagents were used for the analysis: acetone, hexane, isopropanol, ethyl acetate, methanol and acetonitrile (Tedia, Brazil), and glacial acetic acid (Vetec, Brazil).
The vitamin E standards (α-, β-, γ-, and δ-tocopherols and tocotrienols) were acquired from Calbiochem®, EMD Biosciences, Inc. (USA). The α-carotene and β-carotene patterns were isolated from concentrated carrot extract; β-cryptoxanthin and lycopene were isolated from tomato and papaya extracts, respectively, by open-column chromatography [25 (link)].
For the filtration of the samples, it was used filter paper no. JP41 J. (Prolab, Brazil), HV Millex filter units, in polyethylene with 0.45 μm of porosity (Millipore, Brazil) and 3 ml sterilized disposable syringes (TKL, China).