Sodium carbonate

Folin–Ciocalteu’s phenol reagent, ferric chloride hexahydrate (FeCl₃·6H₂O), ferrous sulfate heptahydrate (FeSO₄·7H₂O), and hydrogen chloride (hydrochloric acid ≥ 37% w/w) were purchased from Chem-Lab NV (Zedelgem, Belgium). Sodium carbonate was obtained from Carlo Erba Reagents (Cornaredo, Italy), and absolute ethanol and acetic acid from Merck KgaA (Darmstadt, Germany). Gallic acid (3,4,5-trihydroxybenzoic acid), 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid ammonium salt) (ABTS non radical form) and 2,4,6-tris(2-pyridyl)-s-triazine (TPTZ) were bought from Alfa Aesar (Karlsruhe, Germany), while Trolox (6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid) and potassium persulfate were supplied from Sigma-Aldrich (St. Louis, MO, USA). Standard phenolic compound of chlorogenic acid (≥99%) was purchased from Extrasynthese (Genay, France), and naringenin (97%) and 4-chloro-4’-hydroxybenzophenone (97%) were from Alfa Aesar (Karlsruhe, Germany). Formic acid was bought from LGC Standards (Wesel, Germany). All reagents used for the spectrophotometric assays were of analytical grade (≥94%). Solvents used for all experimental analyses were of LC-MS grade and were purchased from Sigma Aldrich Co. (Gillingham, United Kingdom), Carlo Erba Reagents (Val de Reuil, France), Chem-Lab NV (Zedelgem, Belgium), Fischer-Scientific (Loughborough, UK), and Merck KGaA (Darmstadt, Germany).

All solvents of analytical grade, water (HPLC grade), acetonitrile (HPLC grade) and sodium carbonate were purchased from Carlo Erba Reagent (Milan, Italy).
Folin-Ciocâlteu reagent, 2,2-diphenyl-1-picrylhydrazyl radical, 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) diammonium salt, Trolox (6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid), aluminium chloride, gallic acid, quercetin, ferulic acid, chlorogenic acid, 3-(4,5-dimethylthiazol- 2-yl)-2,5-diphenyltetrazolium bromide reagent (MTT), menadione, 2′-7′-Dichlorofluorescein diacetate (DCF-DA) and fetal bovine serum (FBS) were purchased from Sigma Aldrich S.r.l., Milan (MI), Italy, Syringe filters in PVDF, pore size 0.45 µm (Millipore) were from SER.DIA s.r.l., Reggio Calabria (RC), Italy

Standards of gallic acid, quercetin, cyanidin chloride, caffeic acid, quercetin-3-O-glucoside and tryptophan were purchased from Sigma-Aldrich (Saint-Quentin Fallavier, France). Folin-Ciocalteu’s reagent (10%), aluminum chloride (AlCl₃) (10%), potassium acetate (1 M), DPPH, Trolox (6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid), ABTS (7 mM), potassium persulfate (2.45 mM), ferric chloride (FeCl₃·6H₂O), 2,4,6-tri(2-pyridyl)-s-triazine (TPTZ), methyl-tert-butyl-ether (MTBE),2,2’-Azobis(2-amidinopropane) dihydrochloride (AAPH), fluorescein, sodium nitroprusside (5 mM), sulphanilamide, n-(1-naphthyl) ethylenediamine dihydrochloride phosphate buffered saline (PBS) acetate buffer, phosphate buffer, and mEthanol were supplied by Sigma-Aldrich (Saint-Quentin Fallavier, France). Ethanol, hexane, acetone, formic acid, and sodium carbonate (75 g/L), were purchased from Carlo Erba Reagents (Val de Reuil, France); hydrochloric acid, butanol, acetonitrile, ethyl acetate, phosphoric acid, and ferric ammonium sulfate (2%) were from HoneyWell Riedel-de Haën (Seelze, Germany). All solvents were of the highest analytical grade.

Wet-jet milling exfoliated graphene powder was provided by BeDimensional Srl, Italy. Reduced graphene oxide (rGO) in flake form was purchased from Graphenea, Spain. 1-Methyl-2-pyrrolidinone (ReagentPlus, 99%), N,N-dimethylformamide (anhydrous, 99.8%), ethanol (puriss, ≥96%), N-methylglycine (98%), and 3,4-dihydroxybenzaldehyde (97%) were purchased from Sigma-Aldrich/Merck, Germany, while sodium carbonate (for analysis, ≥99.5%) was purchased from Carlo Erba, Italy.

Ethanol absolute was obtained from Carlo Erba (Milan, Italy). Acetic acid, acetonitrile, methanol, and water (high performance liquid chromatography—HPLC grade) were purchased from VWR (Milan, Italy).
α-pinene, β-pinene, linalool, β-myrcene, terpinolene, caryophyllene, humulene, and β-bisabolene, gallic acid, p-OH benzoic acid, chlorogenic acid, vanillic acid, caffeic acid, syringic acid, ferulic acid, and rosmarinic acid (from Sigma-Aldrich, Darmstadt, Germany) standards were employed. Working standard mixtures were prepared by appropriate dilution of the standards in methanol. All solutions were stored at −20 °C in the dark.
Folin–Ciocâlteu’s reagent, 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (Trolox), 2,2-diphenyl-1-picrylhydrazyl (DPPH˙), and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) diammonium salt (ABTS˙⁺) were purchased from Sigma-Aldrich (Darmstadt, Germany). Sodium carbonate, potassium persulfate, potassium hexacyanoferrate(III), trichloroAcetic acid, ferric chloride, and potassium phosphate monobasic were obtained from Carlo Erba (Milan, Italy).

The following were used in the study: Folin-Ciocalteu’s phenol reagent (Panreac), sodium carbonate, sodium hydroxide, ammonium acetate (Carlo Erba), sodium nitrite 98%, iron (II) sulfate heptahydrate, iron (III) chloride hexahydrate and 2,4,6-tri-(2-pyridyl)-1,3,5-triazine (TPTZ) 98%, (Alpha Aesar), anhydrous aluminum chloride, hydrochloric acid, n-butanol (Merck), Trolox 97% (Acros Organics), gallic acid, (+)-catechin, daidzein (Sigma Aldrich), cyanidine chloride, (−)-epicatechin, kaempferol-3-rutinoside, isorhamnetin-3-O-rutinoside, isorhamnetin-3-O-glucoside (Extrasynthese). All materials used had a high purity, above 95%.