α amyrin

δ-tocopherol, (+)-γ-tocopherol, (±)-α-tocopherol, D-α-tocotrienol, D-δ-tocotrienol, γ-tocotrienol (analytical standards), methyl palmitate (≥99.0%), methyl stearate (≥99.5%), methyl oleate (≥99.0%), methyl linoleate (≥98.5%), methyl linolenate (≥99.0%), betulinic (≥98%), oleanolic (≥97%), ursolic (≥90%) acids, α-amyrin (≥98%), β-amyrin (≥98.5%), lupeol (≥94%), chlorogenic (≥95%), neochlorogenic (≥98%) acids, kaempferol (≥90%), apigenin (≥97%), myricetin (≥96%), quercetin (≥95%), 2-propanol (99.9%), hexane (≥95%), gradient grade acetonitrile, methanol. and ethanol, trifluoroacetic acid (≥99%), and trimethylsulfonium hydroxide (TMSH) (0.25 M methanolic solution) were purchased from Sigma Aldrich (St. Louis, MO, USA). lupeol acetate (≥98%), α-amyrin acetate (≥98%), and β-amyrin acetate (≥98%) were provided by ALB Technology (ALB Materials Inc, Henderson, NV, USA). Water for HPLC was purified by ULTRAPURE Millipore Direct-Q^® 3UV-R (Merck Millipore, Billerica, MA, USA). Tert-butyl methyl ether (TBME) (99.8%) was purchased from Avantor Performance Materials Poland S.A. (Gliwice, Poland).

All the chemicals used in the experiments were of an analytical grade. Cyanidin chloride, cyanidin-3-galactoside, cyanidin-3-glucoside, cyanidin-3-arabinoside, peonidin chloride, peonidin-3-arabinoside, peonidin-3-glucoside, peonidin-3-galactoside, myricetin-3-galactoside, malvidin-3-galactoside, malvidin chloride, malvidin-3-arabinoside, delphinidin-3-galactoside (Extrasynthese, Genay, France), quercetin-3-O-glucoside (Biochemistry, Buchs, Switzerland), quercetin-3-galactoside, quercetin (Carl Roth, Karlsruhe, Germany), myricetin, quercetin-3-rhamnoside, quercetin-3-α-l-arabinofuranoside, quercetin-3-α-l-arabinopyranoside, oleanolic acid, ursolic acid, α-Amyrin, β-Amyrin, corosolic acid, and maslinic acid (Sigma-Aldrich, Steinheim, Germany) were used as standards for the identification of the compounds. Acetone, methanol, acetonitrile, hydrochloric acid, and 4-(Dimethylamino) cinnamaldehyde) were purchased from Sigma-Aldrich (Steinheim, Germany). Ethanol 96% (v/v) was purchased from AB Stumbras (Kaunas, Lithuania). Formic acid was bought from Merck (Darmstadt, Germany).

All solvents, reagents, and standards were of analytical reagent grade. Acetone, methanol, acetonitrile, hydrochloric acid, 4-(Dimethylamino) cinnamaldehyde and reference standarts for β-Amyrin, maslinic acid, oleanolic acid, corosolic acid, ursolic acid, α-Amyrin, quercetin-3-rhamnoside, myricetin, quercetin-3-α-L-arabinopyranoside and quercetin-3-α-L-arabinofuranoside were purchased from Sigma-Aldrich (Steinheim, Germany). Ethanol 96% (v/v) was purchased from AB Stumbras (Kaunas, Lithuania), formic acid was bought from Merck (Darmstadt, Germany), and Trolox (6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid) was purchased from Scharlau (Sentmenat, Spain). Reference standards for myricetin-3-galactoside, cyanidin chloride, peonidin chloride, malvidin-3-galactoside, malvidin-3-arabinoside, malvidin chloride, peonidin-3-arabinoside, cyaniding-3-galactoside, delphinidin-3-galactoside, peonidin-3-glucoside, peonidin-3-galactoside, cyaniding-3-glucoside and cyaniding-3-arabinoside were purchased from Extrasynthese (Genay, France). Standards for quercetin and quercetin-3-galactoside were purchased from Carl Roth (Karlsruhe, Germany). The standard for quercetin-3-O-glucoside was bought from Biochemistry (Buchs, Switzerland). Purified deionized water was provided using a water purification system (Milli-Q^®, Millipore, Bedford, MA, USA).

α-amyrin and β-amyrin of 98.5% purity were purchased from Sigma-Aldrich (Shanghai, China). Ursolic acid and oleanolic acid of 98% purity were purchased from Energy Chemical (Shanghai, China). Hederagenin of 98% purity was bought from TCI (Shanghai, China). Gypsogenic acid of 95% purity was purchased from TRC (Beijing, China). α-Boswellic acid of 98% purity was purchased from PUSH BIO-TECHNOLOGY (Sichuan, China).

Commercially available standards of ten studied pentacyclic triterpenoids—friedelin (tech. grade), betulinic acid (≥97.0%), oleanolic acid (≥97.0%), ursolic acid (≥90.0%), lupeol (≥90.0%), β-amyrin (≥98.5%), α-amyrin (≥98.5%), erythrodiol (≥97.0%), betulin (≥98.0%), and uvaol (≥95.0%)—were purchased from Sigma-Aldrich (Steinheim, Germany).
HPLC gradient grade methanol and isopropanol (Chimmed, Moscow, Russia), and carbon dioxide (≥99.99%, Kriogen, Moscow, Russia) were used for the preparation of mobile phase. Methanol was also used for analyte solution preparation and PLE extraction of plant materials.
The stock solutions of triterpenoids in methanol (250 mg·L⁻¹) were prepared from an accurate sample. Calibration solutions of analytes were prepared by mixing and successive dilutions of the stock solutions with methanol. The solutions were stored in the dark at 4 °C for no more than one week. Stability was checked once a day.

All reagents, standards, and solvents were of analytical reagent grade. Ethanol 96% (v/v) was bought from AB Stumbras (Kaunas, Lithuania). Solvents (acetone, methanol, and acetonitrile), reagents (hydrochloric acid and 4-(dimethylamino) cinnamaldehyde), and reference standards (myricetin, quercetin-3-rhamnoside, quercetin-3-α-L-arabinofuranoside, quercetin-3-α-L-arabinopyranoside, oleanolic acid, β-amyrin, corosolic acid, maslinic acid, α-amyrin, and ursolic acid) were bought from Sigma-Aldrich (Steinheim, Germany). Trolox (6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid) was purchased from Scharlau (Sentmenat, Spain). Formic acid was purchased from Merck (Darmstadt, Germany). The standard for quercetin-3-glucoside was purchased from Biochemistry (Buchs, Switzerland). Standards for quercetin-3-galactoside and quercetin were bought from Carl Roth (Karlsruhe, Germany). Reference standards for peonidin chloride, cyanidin chloride, myricetin-3-galactoside, malvidin-3-galactoside, malvidin chloride, malvidin-3-arabinoside, cyaniding-3-galactoside, peonidin-3-arabinoside, peonidin-3-glucoside, delphinidin-3-galactoside, cyaniding-3-glucoside peonidin-3-galactoside, and cyaniding-3-arabinoside were bought from Extrasynthese (Genay, France).

Ten commercially available pentacyclic triterpenoids—betulinic acid (≥97.0%), oleanolic acid (≥97.0%), ursolic acid (≥90.0%), lupeol (≥90.0%), α-amyrin (≥98.5%), β-amyrin (≥98.5%), 3β-taraxerol (≥95%), betulin (≥98.0%), erythrodiol (≥97.0%), and uvaol (≥95.0%) were purchased from Sigma-Aldrich (Steinheim, Germany).
HPLC gradient grade methanol, acetonitrile, ethyl acetate, isopropanol (Chimmed, Moscow, Russia), formic acid (≥96%, Sigma-Aldrich, St. Louis, MO, USA), and ammonium formate (10 M aqueous solution, Sigma-Aldrich, St. Louis, MO, USA) were used for the preparation of the mobile phase and in the plant material pressurized liquid extraction (PLE) procedure. Deionized water with a resistivity of 18.2 MΩ cm was obtained using a Simplicity UV system (Millipore, Molsheim, France).
The stock solutions of PCTs in methanol (250 mg L⁻¹) were prepared from an accurately weighed sample. Calibration solutions of analytes were obtained by mixing successive dilutions of the stock solutions with methanol. All prepared solutions were stored in the dark at 4 °C for no more than one week. Their stability was checked once a day.