Apigenin

The used standards are protocatechic acid (Koch-Light Laboratories LTD, Bucks, UK), cinnamic acid (Rhône-Poulenc, Paris, France), chlorogenic acid (Sigma-Aldrich, St. Louis, MO, USA), vanillic acid (Merck, Darmstadt, Germany), gallic acid (Prolabo, Paris, France), rosmarinic acid (Extrasynthèse, Genay, France), Coumarin (Behringer, Willich, Germany), apigenin (obtained from Carl Roth, Karlsruhe, Germany), ferulic acid, and caffeic acid (purchased from Sigma, USA) as well as herniarine, luteolin, and myricetin (purchased from Sarsyntex, Merignac, France). Methanol (Carlo Erba Reagents, Val-de-Reuil, France) and formic acid (Carlo Erba Reagents^TM, Cornaredo, Italy) were of HPLC grades. Acarbose, α-amylase and α-glucosidase were purchased from Sigma Aldrich (St. Louis, MO, USA). D(+)-glucose anhydrous, sucrose, starch and phloridzin were purchased from Sigma Aldrich (Riedel-de Haen, Seelze, Germany). Glucose oxidase-peroxidase (GOD-POD) kit was purchased from Biosystems (Barcelone, Spain). All the chemicals used were of analytical grades.

References used for the HPLC-MS analysis were purchased from Sigma Aldrich (St. Louis, MO, USA): Chlorogenic acid, p-coumaric acid, caffeic acid, rutin, apigenin, quercetin, isoquercitrin, quercitrin, hyperoside, kaempferol, myricetol, and fisetin, Roth (Karlsruhe, Germany): Ferulic acid, sinapic acid, gentisic acid, gallic acid, patuletin, luteolin or from Dalton (Toronto, ON, Canada): cichoric acid, caftaric acid. HPLC grade solvents, analytical grade acids used for mobile phases and Folin-Ciocâlteu reagent were purchased from Merck (Darmstadt, Germany), together with sodium carbonate, dipotassium hydrogen phosphate, potassium dihydrogen phosphate and aluminium chloride used for antioxidant assays. ABTS (2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt) ≥98% purity, potassium peroxodisulfate (≥99% purity), DPPH, and Trolox (6-hydroxy-2,5,7,8-tetramethylchromane-2-carboxylic acid; ≥97% purity) also used in antioxidant tests were purchased from Sigma Aldrich (Schnelldorf, Germany). Gallic acid monohydrate (99.5%) was purchased from Serva, (Heidelberg, Germany).

Dichloromethane, acetone, ethyl acetate, and n-butanol for plant material extraction were purchased from Merck KGaA (Darmstadt, Germany). Acetonitrile (LC-MS grade), formic acid (98%), and methanol (LC-MS grade) for LC-MSⁿ analyses were obtained from Sigma–Aldrich (Steinheim, Germany). Purified water (0.056 μS/cm) from a Purelab Option-Q system (Elga Berkefeld GmbH, Celle, Germany) was used throughout. The DPPH photometric assay and the quantitation of total phenolic compounds were performed with 2,2-diphenyl-1-picryl hydrazyl radical (DPPH), Folin–Ciocalteu’s phenol reagent, and sodium carbonate from Th. Geyer GmbH & Co. KG (Renningen, Germany). The following reference substances were used: luteolin and 5-caffeoylquinic acid (chlorogenic acid) from PhytoLab GmbH & Co. KG (Vestenbergsgreuth, Germany); quercetin-3-O-rutinoside, apigenin, and apigenin-7-O-glucoside from Carl Roth GmbH & Co. KG (Karlsruhe, Germany); gallic acid monohydrate from Sigma–Aldrich (Steinheim, Germany); and Trolox from Cayman Chemical (Ann Arbor MI, USA).

The used standards are luteolin, herniarin and myricetin (purchased from Sarsyntex, Merignac, France), apigenin (obtained from Carl Roth, Karlsruhe, Germany), coumarin (Behringer, Willich, Germany), cinnamic acid (Rhône-Poulenc, Paris, France), protocatechuic acid (Koch-Light Laboratories LTD, Bucks, UK), vanillic acid (Merck, Darmstadt, Germany), chlorogenic acid (Sigma-Aldrich, St. Louis, MO, USA), rosmarinic acid (Extrasynthèse, Genay, France) and gallic acid (Prolabo, Paris, France), as well as ferulic acid and caffeic acid purchased from Sigma (St. Louis, MO, USA). Formic acid (Carlo Erba Reagents^TM, Cornaredo, Italy) and methanol (Carlo Erba Reagents, Val-de-Reuil, France) were of HPLC grades. All other chemicals used were also of analytical grade.

Fresh raspberries (R. idaeus, cv. Remontant, from Domeniul Cerbi, Marginea, Suceava, Romania) and multifloral honey (RomHoney Group, Iași, Romania) were used in this work. The raspberries were dried by lyophilization and were ground to a fine powder using an electrical grinder. The following chemicals were used: pharmaceutical ethanol 96% (Chimopar Srl, Bucharest, Romania), D(+)-Glucose anhydrous extra pure, D(−)-Fructose, extra pure, D(+) Saccharose, reagent grade (Scharlau, Barcelona, Spain) Trolox 97% (Acros Organics, Thermo Fisher Scientific, Pittburghs, PA, USA), Gallic acid, 2,2-Diphenyl-1-picrylhydrazyl (Sigma-Aldrich, Merck Group, Darmstad, Germany), 2,2′-Azino-bis (3-ethylbenzothiazo-line-6-sulfonic acid) diammonium salt, 98%, 2,4,6-tri (2-pyridyl-1,3,5-triazine) 98% (Alfa Aesar, Kandel, Germany), Folin Ciocalteu’s phenol reagent, Iron chloride (III) (Merck, Darmstadt, Germany), hydrochloric acid, acetic acid (Chimopar Srl, Bucharest, Romania), sodium acetate (Scharlau, Barcelona, Spain), HPLC standards: ferulic acid, p-coumaric acid, caffeic acid, quercetin dihydrate (Sigma-Aldrich, Merck Group, Darmstad, Germany), syringic acid, luteolin, (+)-rutin trihydrate, (Alfa Aesar, Haverhill, MA, USA), chlorogenic acid, myricetin (Cayman Chemical, Ann Arbor, MI, USA), apigenin, (−) epicatechin (Roth, Karlsruhe, Germany), and kaempferol (Cayman Chemical, Ann Arbor, MI, USA).

Analytical standards (all with purity ≥ 95%) of caffeic, 5-O-caffeoylqunic, gallic, ferulic, isoferulic, homoGentisic, protocatechuic, 3-hydroxybenzoic, 4-hydroxybenzoic, rosmarinic, 3,4-dihydroxyphenylacetic, vanillic, syringic, m-coumaric, o-coumaric, p-coumaric, salicylic, 3,4-dimethoxycinnamic, α-resorcylic, β-resorcylic, γ-resorcylic, 3,5-dimethoxybenzoic acid, 3-O-methylquercetin, chrysin, isorhamnetin, kaempferol, luteolin, morin, prunetin, rhamnetin, sakuranetin, taxifolin, and LC grade acetonitrile, methanol were purchased from Sigma-Aldrich Fine Chemicals (St. Louis, MO, USA). Gentisic, sinapic, veratric acids, eriodictyol, myricetin and rhamnazin were from ChromaDex (Irvine, USA). Apigenin and naringenin were from Roth (Karlsruhe, Germany) and quercetin was from Fluka (Buchs, Switzerland). LC grade water was prepared using a Millipore Direct-Q3 purification system (Bedford, MA, USA).