Pinoresinol

Methyl alcohol HPLC grade and glacial acetic acid were purchased from VWR International Srl (Milan, Italy), water HPLC grade was obtained by using purification units (ELGA, Germany). Hydroxytyrosol (3,4-DHPEA) and tyrosol (p-HPEA) were supplied by Cabru s.a.s. (Arcore, Milan, Italy). The dialdehydic forms of elenolic acid linked to 3,4-DHPEA and p-HPEA (3,4-DHPEA-EDA and p-HPEA-EDA, respectively), the isomer of oleuropein aglycon (3,4-DHPEA-EA), (+)-1-acetoxypinoresinol were extracted from virgin olive oil according to the procedure reported from Selvaggini et al., 2014. (+)-Pinoresinol was purchased from PhytoLab GmbH & Co. KG (Vestenbergsgreuth, Germany). Pure analytical standards of volatile compounds were obtained from Merck (Milan, Italy).

ABTS (2,2′-azinobis-(3-ethylbenzthiazoline-6-sulfonic acid)) (CAS: 30931-67-0) and DPPH (2,2-diphenyl-1-picrylhydrazyl) (CAS: 1898-66-4) were purchased from Sigma-Aldrich^® (Darmstadt, Germany); gallic acid, potassium peroxodisulfate and Na₂CO₃ were purchased from Fluka (Darmstadt, Germany); methanol was purchased from Carlo Erba (Milan, Italy); and Folin–Ciocalteu (FC) reagent was purchased from Merck (Darmstadt, Germany). The solvents used for the high-performance liquid chromatography (HPLC) were of HPLC-grade purity; methanol, water and acetonitrile were obtained from J. T. Baker (Gliwice, Poland) and trifluoroacetic acid was obtained from Fisher Scientific (Loughborough, U.K.). Reference standard compounds were used for confirmation of identity and HPLC quantification: matairesinol (CAS: 580-72-3), (+)-isolariciresinol (CAS: 549-29-8) and (−)-hydroxymatairesinol (CAS: 347359-71-1) were obtained from Sigma-Aldrich^® (Darmstadt, Germany); secoisolariciresinol (CAS: 145265-02-7) was obtained from Fluka (Darmstadt, Germany); and (+)-lariciresinol (CAS: 27003-73-2) and (+)-pinoresinol (CAS: 487-36-5) were obtained from PhytoLab (Dutendorfer, Germany).