M hydroxybenzoic acid

3,4,5-trihydroxybenzoic acid (GA), 3,5-dihydroxybenzoic acid (3,5-DHBA), 3,4-dihydroxybenzoic acid (PCA), 5-caffeoylquinic acid (5CQA), 2,5-dihydroxybenzoic acid (2,5-DHBA), catechin (Cat), 4-caffeoylquinic acid (4CQA), p-hydroxybenzoic acid (pHBA), vanillic acid (VA), caffeic acid (CA), syringic acid (SyA), m-hydroxybenzoic acid (mHBA), 2,6-dihydroxybenzoic acid (2,6-DHBA), cumaric acid (CuA), sinapic acid (SA), ferulic acid (FA), rutin (Ru), myricitrin (My), quercetin-3-O-glucoside (Q3G), kampferol-3-O-rutinoside (K3R), salicylic acid (SaA), hesperidin (He), quercetin (Q), kampferol (K), isoxanthohumol (IsoX), xanthohumol (X), formic acid, and dichloromethane, were purchased from Sigma-Aldrich (Milano, Italy). HPLC-grade acetonitrile and methanol were Carlo Erba (Milano, Italy); HPLC-grade water was prepared with the Milli-Q purification system (Millipore, Vimodrone, Italy).

Gallic acid (3,4,5-trihydroxybenzoic acid), Caffeic acid, p-Coumaric acid, Ferulic acid, Luteolin, Quercetin, t-Cinnamic acid, Apigenin, Hesperidin, Rhamnetin, Chrysin, Pinocembrin, Protocatechuic acid, Chlorogenic acid, p-hydroxybenzoic acid, Epicatechin, Syringic acid, m-hydroxybenzoic acid, Ellagic acid, Myricetin, Resveratrol, Daidzein, Curcumin, Caffeic acid phenethyl ester (CAPE), 2,2-diphenyl-1-picrylhydrazyl (DPPH), Ascorbic acid were obtained from Sigma-Aldrich. Butylated hydroxytoluene (BHT), 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS), 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (Trolox), were purchased from Fluka, USA. Potassium persulfate, Sodium carbonate, Folin–Ciocalteu solution, Aluminium chloride, Ethanol 96%, Methanol, were purchased from POCH, Poland.

Standards of phenolic acids and flavonoids (apigenin, 2,3-dihydroxybenzoic acid, caffeic acid, catechin, chlorogenic acid, chrysin, ferulic acid, galangin, gallic acid, hesperidin, m-hydroxybenzoic acid, p-hydroxybenzoic acid, 5-hydroxyferulic acid, kaempferol, methyl p-coumarate, morin, myricetin, naringenin, naringin, p-coumaric acid, pinocembrin, quercetin, quercitrin, rosmarinic acid, rutin, salicylic acid, salicylic acid glucoside, sinapic acid, syringic acid, trans-cinnamic acid, vanillic acid, p-coumaric acid-d₆, and salicylic acid-d₄) were purchased from Sigma-Aldrich (Steinheim, Germany).
The sodium molybdate dihydrate, sodium nitrite, sodium hydroxide, sodium carbonate, hydrogen peroxide, sodium ascorbate, dimethyl sulfoxide (DMSO), and bovine hemoglobin were also purchased from Sigma-Aldrich (Steinheim, Germany). The LC (liquid chromatography) grade methanol, analytical grade orthophosphoric acid, hydrochloric acid, aluminum chloride, sodium acetate, ethanol, and Folin–Ciocalteu reagent were purchased from Merck (Darmstadt, Germany). The DPPH (2,2-diphenyl-1-picrylhydrazyl) was obtained from Alfa-Aesar (Karlsruhe, Germany). All spectrophotometric data were acquired using a Jasco V-530 UV-Vis spectrophotometer (Jasco International Co., Ltd., Tokyo, Japan).