α chaconine

Fresh juices from potatoes of 3 varieties (‘Agata’, ‘Queen Anne’ and ‘Vivaldi’, denoted as ‘APJ’, ‘QAPJ’ and ‘VPJ’, respectively) were obtained by thoroughly washing and peeling the tubers, and then squeezing the juice using a VitaJuice 4 juicer (Robert Bosch GmbH, Gerlingen-Schillerhöhe, Germany). Each time, the juice obtained was centrifuged at 4 °C (3000× g) in order to separate the starch remaining in the juice, and then the juice was decanted, frozen, and freeze-dried.
Industrial potato juice (IPJ) and deproteinized potato juice water (DPJ) were collected from PPZ Trzemeszno S.A. (Trzemeszno, Poland) as a side stream of the potato starch extraction process.
Moreover, the research used potato juice protein concentrate (MPP), obtained according to the membrane method described in detail earlier [6 (link)], commercial potato protein Solanic^®200 (NPP) purchased from Avebe (Veendam, The Netherlands), and feed potato protein (FPP) obtained from PPZ Trzemeszno S.A. (Trzemeszno, Poland).
α-Solanine and α-chaconine were purchased from Phytolab GmbH & Co. KG (Vestenbergsgreuth, Germany). Pork pepsin, porcine pancreatin, bile salt, caffeic, chlorogenic, ferulic, and gallic acids were purchased from Sigma-Aldrich (Steinheim, Germany). All other reagents, purity min. HPLC grades were purchased from Merck Life Science (Darmstadt, Germany).

The HPLC-grade solvents such as methanol (MeOH) and ethanol (EtOH) were obtained from Scharlab (Barcelona, Spain), and acetonitrile (ACN) was obtained from Fisher Chemical (Madrid, Spain). Monosodium phosphate (NaH₂PO₄) and disodium phosphate (Na₂HPO₄) were purchased from Panreac (Barcelona, Spain). Ultrapure deionized water with a resistance of 18.2 MΩ cm was obtained by a Milli-Q system (Billerca, MA, USA). Nylon syringe filters (0.45 μm, 13 mm) were purchased from Scharlab (Barcelona, Spain). For standard solutions preparation, α-solanine (>99%) and α-chaconine (>99%), purchased from Phytolab (Madrid, Spain), were used. Individual stock standard solutions of α-solanine and α-chaconine were prepared at a concentration of 200 μg/mL in MeOH and stored at −20 °C. The calibration standards were prepared at the appropriate concentrations (1, 2.5, 5, 10, 25, 50, and 100 mg/L for both analytes) by serial dilution of the stock solutions in MeOH. The prepared solutions were stored in the dark at a temperature of −20 °C.

LC-MS grade methanol (LC-MS LiChrosolv^®, Merck (≥99.97%), formic acid (98–100%), water (LC-MS Chromasolv), trans-zeatin (≥97%), solasodine (≥95%), tomatidine hydrochloride (≥85%), α-solanine (≥95%), solanidine (≥95%), phenylalanine (≥98%), tyrosine (≥98%), tryptophan (≥95%), methyl dihydrojasmonate (≥96%), and DMSO (≥99.9%) were purchased from Sigma-Aldrich (St. Louis, MO, United States) and α-chaconine (≥95%) (PhytoLab, Germany).