Antioxidant properties and polyphenolics composition of common hedge hyssop (Gratiola officinalis L.)

The antioxidant potential of Gratiola officinalis was evaluated by the off-line and on-line HPLC/UV/DPPH radical scavenging assays, phytochemical composition was analyzed by LC/MS. On-line method was validated by using reference antioxidants and linear dependence was found between their concentration and radical scavenging peak area. Radical scavenging capacity (RSC) of methanol and acetone extracts expressed in their concentration required to scavenge 50% of DPPH• was 0.10% and 0.13%, respectively; the RSC in ABTS•+ assay was 1093 ± 104 and 746 ± 18 μM of trolox equivalents in 1 g, respectively. Good correlation was observed between total amount of phenolic compounds and RSC. Preliminary HPLC/UV/MS analysis revealed that the main compounds possessing antioxidant activity in the extracts might be phenylpropanoid glycosides; UPLC/UV/ESI-QTOF-MS analysis suggested 15 structures: 2,5-dihydroxy-p-benzenediacetic and caffeic acids, apigenin 6,8-di-C-β-d-glucopyranoside (vicenin-2), apigenin 8-C-α-l-arabinoside 6-C-β-d-glucoside, (shaftoside), forsythoside B, arenarioside, verbascoside (acteoside), amioside, quercetin-6-O-(2-O-acetyl-glucopyranosyl)-glucopyranoside, isoverbascoside, quercetin glucuronide, linariifolioside, methoxy luteolin-7-O-(6-O-acetyl-glucopyranosyl)-glucopyranoside, methoxy luteolin-glucuronide and luteolin glucuronide.