Cryptoxanthin

Carotenoids were extracted by liquid–liquid extraction from plasma samples collected at 0 h and 24 h [32 (link)]. Chromatographic analysis of carotenoids was performed by HPLC-UV-DAD, using an HP 1100 HPLC system (Hewlett-105 Packard, Waldbronn, DE) containing a quaternary pump coupled to a DAD G1315B. The separation was carried out with Milli-Q water, methanol (MeOH) and methyl-tert-butyl ether (MTBE) (Panreac Quimica S.A., Barcelona, Spain), according to a procedure previously validated in our group [32 (link)]. A Waters RP column YMC Carotenoid S-5 µm (250 mm × 4.6 mm) and a precolumn YMC Guard Cartridge Carotenoid S-5 µm (20 mm × 4.0 mαm) were used.
Zeaxanthin (Extrasynthese, Genay, France), lutein, cryptoxanthin, α-carotene, β-carotene 9- and 13-cis-β-carotene (Sigma-Aldrich, St. Louis, MO, USA), lycopene (Fluka, Bucks, Switzerland), and 5-cis-lycopene (CaroteNature GmbH, Münsingen, Switzerland) were used as standards. These were pooled and prepared in synthetic human plasma (Sigma-Aldrich, St. Louis, MO, USA).
The sensitivity of each analyte was 0.703 µmol/L (lutein), 0.352 µmol/L (Zeaxanthin), 0.362 µmol/L (cryptoxanthin), 0.480 µmol/L (trans-β-apo-8’-carotenal), 0.745 µmol/L (13-cis-β-carotene), 0.373 µmol/L (9-cis-β-carotene and trans-β-carotene), and 0.186 µmol/L (trans and cis-lycopenes) [32 (link)].

Carotenoids and fat-soluble vitamin standards: E-β-apo-8′-carotenal, α-carotene, 13-Z-β-carotene, cryptoxanthin, lutein, zeaxanthin, astaxanthin, cantaxanthin, β-carotene, 9-Z-β-carotene, retinol, retinol acetate, 25-hydroxycholecalciferol, cholecalciferol and α-tocotrienol were purchased from Sigma-Aldrich (St. Louis, MO, USA). The standard of 5-Z-lycopene was supplied by CaroteNature GmbH (Ostermundigen, Switzerland).
MeOH of LC-MS grade, n-hexane, ethanol and MTBE of HPLC grade, synthetic plasma and butylated hydroxytoluene (BHT) were obtained from Sigma-Aldrich. AMAC and AA of HPLC grade were purchased from Panreac Quimica SA (Barcelona, Spain). Ultrapure water (Milli-Q) was generated by a Millipore system (Millipore, Bedford, MA, USA).