Ascorbic acid

The plant material of the Berberis vulgaris L. barberry stem, leaves, and fruits was obtained from the Maria Curie-Skłodowska University Botanical Garden in Lublin in September 2020 (Voucher specimen: AO2020091). The raw material was separated and dried at room temperature in the shade with ventilation. The raw material was weighed and ground in an electric mill and portioned, vacuum-packed, and stored in a closed package at −30 °C until the start of the tests. DPPH• (2,2-diphenyl-1-picrylhydrazyl), Trolox, gallic acid, 3-caffeoylquinic acid, protocatechuic acid, 5-caffeoylquinic acid, 4-caffeoylquinic acid, caffeic acid, catechin, luteolin, eriodictyol-7-glucopyranoside, quercetin, syringaresinol-di-O-glucoside, rutin, hyperoside, luteoloside, isoquercetin, narcissoside, isorhamnetin-3-glucoside, quercitrin naringenin 7-glucoside, afzelin, LC grade acetonitrile, Trolox, 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS•+), Folin–Ciocalteu reagent, and 2,2′-azobis (2-methylpropionamide) dihydrochloride (AAPH) were purchased from Sigma–Aldrich (Stenheim, Germany); ascorbic acid was purchased from Stanlab (Poland); methanol and aluminium chloride hexahydrate of analytical grade were purchased from POCH (Gliwice, Poland).

A 2,2-diphenyl-1-picrylhydrazyl (DPPH•), 2,20-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS•+), Folin–Ciocalteu reagent, 2,20-azobis (2-methylpropionamide) dihydrochloride (AAPH), Trolox, acetonitrile and formic acid (both MS grade), berberine (95% purity), and ferulic acid were purchased from Sigma–Aldrich (Stenheim, Germany). Ascorbic acid was purchased from Stanlab (Lublin, Poland), and analytical-grade methanol and aluminium chloride hexahydrate were purchased from POCH (Gliwice, Poland). Ultrapure water was prepared with a Milli-Q purification system (Millipore, Burlington, MA, USA).
The SuperScript Vilo cDNA Synthesis kit was used according to the manufacturer’s recommendations. cDNA was stored at −20 °C until subsequent analysis. PCR reactions were performed using SG onTaq qPCR Master Mix (Eurx, Gdańsk, Poland) on the QuantStudio 5 Real-Time PCR System (Applied Biosystems, Waltham, MA, USA).