β cryptoxanthin

Violaxanthin, neoxanthin, antheraxanthin, lutein, zeaxanthin, phytoene, β-cryptoxanthin, phytofluene, α-carotene, β-carotene, ζ-carotene, δ-carotene, γ-carotene, neurosporene and lycopene were purchased from CaroteNature (Lupsingen, Switzerland). Methanol was purchased from Fisher Scientific (Waltham, MA, USA). Tert-methyl butyl ether (MTBE), chloroform and dichloromethane were purchased from Avantor Performance Materials (Panoli, Gujrat, India), hexane from Sigma chemical Co. (St. Louis, MO, USA) and ethanol from Hayman Ltd. (Essex, USA). All reagents were HPLC grade or higher. A Millipore Milli-Q water purification system was used to obtain high purity of water.

Carotenoids were determined in a saponified sample of paprika extract using the internal standard by HPLC analysis. This methodology was described in the previous paper [51 (link)]. After saponification, carotenoids were analyzed using a Waters Liquid chromatograph equipped with DAD 2996 detector. Separation of carotenoids was carried out using 4.6 × 150 mm chromatographic column YMC^TM Carotenoid with granulation of 3 μm additionally equipped with a protective column YMC^TM Carotenoid S-3. The mobile phase was a mixture of methanol, acetonitrile, and water (75:10:15, v:v:v) in gradient elution with dichloromethane. The flow rate was 1 mL/min and the column temperature was set at 25 °C. The injection volume was 20 μL.
Capsanthin of 96% purity, capsorubin of 98% purity, β-carotene of 99% purity, β-cryptoxanthin of 97% purity, violaxanthin of 95% purity, and zeaxanthin of 97% purity standards purchased from CaroteNature GmbH (Münsingen, Switzerland) were used for identification and quantification based on a calibration curve. β-Apo-8′-carotenal of ≥96% purity obtained from Sigma-Aldrich (Buchs, Switzerland) was used as internal standards. The qualitative analysis was based on a comparison of the retention time of peak with an appropriate carotenoid standard.

Standards of α-carotene, β-carotene and lutein were obtained from Sigma-Aldrich (Schnelldorf, Germany). β-Cryptoxanthin and zeaxanthin were purchased from CaroteNature (Lupsingen, Switzerland. The stock solution for the standards were prepared at the concentration of 50 µg/mL of n-hexane and stored in the dark at −20 °C. Suitable volumes of each stock solution were used to prepare the working solutions.

Authentic chemical standards β-carotene, lutein, β-cryptoxanthin, zeaxanthin, and violaxanthin were purchased from CaroteNature (www.carotenature.com). Butylated hydroxytoluene (BHT) and ampicillin were purchased from Sigma-Aldrich (www.sigmaaldrich.com/united-states.html) and corticosterone from Sigma Canada (www.sigmacanada.ca). All solvents used in this study were HPLC grade.

Standards of lutein, zeaxanthin, β-cryptoxanthin, lycopene, β-carotene and α-carotene were acquired from CaroteNature (GmbH, Lupsingen, Switzerland). HPLC-grade solvents including acetonitrile, methanol and ethyl acetate were obtained from Merck (KGaA, Darmstadt, Germany).

Orange peel samples were lyophilized using a lyophilizer (catalog no. 7960070; LABCONCO FreeZone, USA). Carotenoid extractions were performed as previously described by Zhu et al. (2021b) (link) and Zheng et al. (2019) (link). The extracts were analyzed using high-performance liquid chromatography (e2695; Waters, USA) as previously described (Zheng et al., 2019 (link)). The carotenoids were identified by comparing their retention times with the retention times of authentic standards (β-carotene, catalog no. CTN0003; β-cryptoxanthin, catalog no. 072624203780617; β-citraurin, catalog no. CTN0483; violaxanthin, catalog no. 228915278393478, CaroteNature, Lupsingen, Switzerland). The authentic standards were used to construct standard curves for determining carotenoid concentrations by integrating peak areas. The levels of each carotenoid were quantified by converting the pertinent peak area to a concentration using the appropriate standard curve. An independent extraction from each set of fruit peels was used as one biological replicate. At least three biological replicates from independent extractions for three sets of fruit peels were performed.