2 aminoethyl diphenyl borate

The following chemicals of analytical and gradient grade purity were used: 2-aminoethyl-diphenylborate, 5,5 dimethyl-1-pyrroline-N-oxide (DMPO), 2,2-azino-bis(3-ethyl-benzothiazoline-6-sulphonic acid) salt/cation radical (ABTS/ABTS^•+), acetonitrile, dimethyl sulfoxide (DMSO), (±)-catechin, chlorogenic acid, ethanol, ferulic acid, Folin–Ciocalteu phenol reagent, gallic acid, hesperidin, myricetin, p-coumaric acid, sinapic acid, quercetin, and rutin hydrate (Sigma-Aldrich, St. Louis, MO, USA); potassium persulfate, potassium dihydrogen phosphate, sodium hydrogen phosphate (Merck, Darmstadt, Germany); caffeic acid and luteolin (Alfa Aesar, Ward Hill, MA, USA); formic acid, sodium carbonate, sodium hydroxide (Lachema, Brno, Czech Republic), standard solutions of elements concentration 1 g/L (Analytika, Prague, Czech Republic) and deionized water purified by a Milli-Q A10 Gradient (Millipore Corp., Burlington, MA, USA).

The identification and quantification of secondary metabolites was performed using the techniques reported by Cretu et al. [49 ]. Silica gel plates 60 F 254 of 10 × 20 cm (Merck^®, (Darmstadst, Germany) were used. Plates were activated by heating (TLC Plate Heater 3, CAMAG, Muttenz, Switzerland) at 100 °C for 3 min. After cooling to room temperature (22 °C ± 2), samples were applied (1 g/75 mL) with a sample applicator (ATS 4, CAMAG, Muttenz, Switzerland), and the plate was developed with 10 mL of solvent system in the automated development chamber (ADC 2, CAMAG, Muttenz, Switzerland) at 47% RH (relative humidity) (in equilibrium with a saturated solution of potassium thiocyanate KSCN) for 10 min. The plates were derivatized with a 1% natural products (NP) methanolic solution (2-aminoethyl diphenyl borate, Sigma-Aldrich^®, St. Louis, MO, USA) reagent and derivatization was performed in the immersion device (Chromatogram Immersion Device, CAMAG, Muttenz, Switzerland) at an immersion speed of 5 cm/s with an immersion time of 1 s. After derivatization, the plate was dried for 3 min at 100 °C (TLC Plate Heater 3, CAMAG, Muttenz, Switzerland). Images of each plate were documented using a TLC Visualizer (CAMAG, Muttenz, Switzerland) under visible light, at UV 254 nm and UV 366 nm.
Results were processed via the VisionCATS version 1.4.7.2018 software (CAMAG, Muttenz, Switzerland).

The hydrochloric acid (HCl), lead acetate, ferric chloride, ammonium hydroxide, sodium hydroxide (NaOH), chloroform, sulfuric acid (H₂SO₄), Barfoed’s reagent, Felhing’s solution A and B, copper sulfate, ninhydrin, acetone, acetic anhydride, Folin–Ciocalteu reagent, 2,2-diphenyl-1-picrylhydrazyl radical (DPPH^•), sodium carbonate, aluminum chloride (AlCl₃), sodium nitrite (NaNO₂), ethyl acetate, formic acid, acetic acid, 2-aminoethyl diphenyl borate, potassium ferrocyanide, trichloroacetic acid, ferric chloride, linoleic acid, Tween 20, ferrous chloride, ethylenediaminetetraacetic acid (EDTA), fluorescein, 2,2′-azo-bis(2-amidino-propane)dihydrochloride (AAPH), trolox, ethanol, methanol, and water (HPLC grade) were purchased from Sigma-Aldrich (St. Louis, MO, USA). Plates 20 × 10 cm HPTLC Silica gel 60 F₂₅₄ were purchased from Merck (Kenilworth, NJ, USA).