Sodium carbonate

According to Singleton and Rossi [66 ] and Tsantili [67 (link)], the Folin–Ciocalteu method (Sigma-Aldrich, Saint Louis, MO, USA) was used to determine the total phenolic concentration. In summary, 0.7 mL of distilled water was added to a tube along with 0.25 mL of the methanol extract. After adding 0.75 mL of Folin–Ciocalteu reagent, the tube was swirled and left to stand at room temperature for 6 min. The combination also contained 0.8 mL of 7% sodium carbonate from Lachner, Neratovice, Czech Republic. The mixture was left in the dark for 90 min. A UV-Vis spectrophotometer (Evolution 210, Thermo Fisher Scientific, Waltham, MA, USA) was used to quantify absorbance in comparison with a blank at a wavelength of 760 nm. Gallic acid equivalents were used to quantify the total phenolic content on a dry basis (GAE mg g⁻¹ d.b.).

HPLC 99% pure methanol obtained from Honeywell (Honeywell, Paris, France) was used as an extraction solvent, while Folin–Ciocalteau reagent obtained from Fisher Scientific (Fisher Scientific, Loughborough, UK) was used for spectrophotometric determination of total phenols. Hydrochloric acid (37%, w/w), sulfuric acid (96%, p.a.), sodium carbonate, anhydrous (99.5–100.5%), and formic acid (98%, p.a.) were obtained from Lachner (Lachner s.r.o., Neratovice, Czech Republic). Ethanol (96% pure) was obtained from Gram-mol (Gram-mol d.o.o., Zagreb, Croatia). Quercetin (95%) and gallic acid standard (97.5–102.5%) were purchased from Acros Organics (Acros Organics, Guangzhou, China) and Sigma-Aldrich (Sigma-Aldrich Co., St. Louis, MO, USA). Vanillin (99%), potassium chloride (99.0–100.5%), sodium acetate anhydride (99%), and chlorogenic acid (min. 95%) were purchased from Thermo Fisher (Thermo Fisher GmbH, Kandel, Germany).

Formic acid (98%, p.a.), sodium carbonate, anhydrous (99.5–100.5%), and hydrochloric acid (37%, w/w) were purchased from Lach-Ner (Neratovice, Czech Republic). HPLC grade 99% methanol was purchased from Honeywell (Paris, France). Folin-Ciocalteu reagent was purchased from Fisher Scientific UK (Loughborough, UK). Ethanol (96% pure) was purchased from Gram-Mol (Zagreb, Croatia). Gallic acid standard (97.5–102.5%) and quercetin standard (95%) were obtained from Sigma-Aldrich (St. Louis, MO, USA) and Acros Organics (Guangzhou, China), respectively. Chlorogenic acid reference standard (min. 95%), potassium chloride (99.0–100.5%) and sodium acetate anhydride (99%) were purchased from Thermo Fisher (Kandel, Germany).

HPLC 99% pure methanol was purchased from Honeywell (Paris, France). Folin-Ciocalteau (FC) reagent was obtained from Fisher Scientific UK (Loughborough, UK). Sodium carbonate, anhydrous (99.5–100.5%), sulfuric acid (96%, p.a.), hydrochloric acid (37%, w/w), and formic acid (98%, p.a.) were obtained from Lach-Ner (Neratovice, Czech Republic). Ethanol (96% pure) was purchased from Gram-mol (Zagreb, Croatia). Quercetin (95%) was purchased from Acros Organics (Guangzhou, China). Vanillin (99%) and chlorogenic acid (min. 95%) were obtained from Thermo Fisher (Kandel, Germany). DPPH (2,2-diphenyl-1-picrylhydrazyl radical), gallic acid standard (97.5–102.5%), and TPTZ (2,4,6-tris-2-pyridyl-s-triazine) were obtained from Sigma-Aldrich (St. Louis, MO, USA). Iron (III)-chloride hexahydrate and sodium acetate trihydrate resistant to potassium permanganate were obtained from Kemika (Zagreb, Croatia). Glacial acetic acid (≥99.8%) was purchased from Honeywell Fluka^TM (Seelze, Germany), and Trolox standard (6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid) used for FRAP and DPPH assay was purchased from Biosynth (Bratislava, Slovakia).

HPLC 99% pure methanol obtained from Honeywell (Paris, France) was used as an extraction solvent, while the Folin–Ciocalteu reagent obtained from Fisher Scientific UK (Loughborough, UK) was used for spectrophotometric determination of total phenols. Hydrochloric acid (37%, w/w), sulfuric acid (96%, p.a.), sodium carbonate, anhydrous (99.5–100.5%), and formic acid (98%, p.a.) were obtained from Lach-ner (Neratovice, Czech Republic). Ethanol (96% pure) was obtained from Gram-mol (Zagreb, Croatia). Quercetin (95%), potassium acetate (99%), and aluminum chloride (98.5%) were purchased from Acros Organics (Guangzhou, China). Gallic acid standard (97.5–102.5%), DPPH (2,2-diphenyl-1-picrylhydrazyl radical), and TPTZ (2,4,6-tris-2-pyridyl-s-triazine) were obtained from Sigma-Aldrich (St. Louis, MO, USA). Vanillin (99%), potassium chloride (99.0–100.5%), sodium acetate anhydride (99%), and chlorogenic acid (min. 95%) were purchased from Thermo Fisher (Kandel, Germany). Iron (III)-chloride hexahydrate and sodium acetate trihydrate resistant to potassium permanganate were obtained from Kemika (Zagreb, Croatia). Glacial acetic acid (≥99.8%) was purchased from Honeywell Fluka ^TM (Seelze, Germany) and trolox standard (6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid) used for the DPPH and FRAP method was purchased from Biosynth (Bratislava, Slovakia).