The effect of cyclodextrins on bioavailability of hydroxytirosol, thyrosol and oleuropein from olive pomace extracts

Komina masline je ostatak koji u velikim količinama ostaje nakon proizvodnje maslinovog ulja. Obiluje polifenolima koji pokazuju antioksidativna svojstva. Cilj ovog rada bio je istražiti stabilnost i bioraspoloživost specifičnih biološki aktivnih spojeva komine tijekom in vitro simulacije gastrične i intestinalne probave. Uzorci obuhvaćeni istraživanjem uključuju čisti (nativni) estrakt komine te ekstrakte poboljšanih tehnoloških (organoleptičkih) svojstava pripremljenih korištenjem različitih vrsta ciklodekstrina. Osim istraživanja gastrointestinalne stabilnosti, ispitivanjem permeabilnosti dijalizijskim membranama određena je količina bioraspoložive frakcije polifenola u pojedinim uzorcima. Udio ukupne količine biodostupnih i bioraspoloživih polifenola određen je Folin-Ciocalteu metodom, antioksidacijski kapacitet TEAC metodom, a udio hidroksitirosola, tirosola i oleuropeina primjenom kromatografije (HPLC). Hidroksitirosol je najzastupljeniji od karakterističnih fenola u ekstraktu komine masline (78,4 – 108,7 μg/100mg). Korištenjem ciklodekstrina u pripremi ekstrakata povećan je antioksidacijski potencijal, udio ukupnih fenola te prinosi hidroksitirosola i oleuropeina. Količina ukupnih polifenola i antiradikalni kapacitet uzoraka se tijekom in vitro probave povećavaju neovisno o prisustvu i vrsti ciklodekstrina (porast od 157,3 – 189,9 mg GAE/100 g). Karakteristični fenoli komine masline su stabilni u gastrointestinalnom sustavu osim oleuropeina koji se u intestinalnoj fazi u potpunosti razgrađuje. Prisutnost ciklodekstrina u uzorku komine masline negativno utječe na dijalizabilnost biološki aktivnih spojeva (manja za 4,0% – 20,9%) . Potrebna su daljnja istraživanja na Caco-2 staničnim kulturama i in vivo istraživanja kako bi se dobio bolji uvid u stabilnost i biodostupnost fenola masline.Olive pomace is a by-product that remains in large quantities after olive oil production. It is rich in polyphenols that show antioxidant properties. The aim of this research was to examine the stability and bioavailability of specific biologically active compounds of olive pomace during the in vitro simulation of gastric and intestinal digestion. Samples analysed in the frameworks of this study included native olive pomace extract and extracts with improved tehnological (organoleptic) properties prepared using various types of cyclodextrins. By examining permeability with dialysis membranes, the amount od bioavailable fraction of polyphenols in each individual sample was determined. The share of the total amount of bioaccessible and bioavailable polyphenols was determined by the Folin-Ciocalte method, the antioxidant capacity by the TEAC method, and the share of hydroxytrosol, tirosol and oleuropein by chromatography (HPLC). Hydroxytyrosol was the most abundant among the specific phenols of olive pomace (78,4 – 108,7 μg / 100mg). By using cyclodextrins for olive pomace extract preparation, the antioxidant potential, the share of total phenols and the yields of hydroxytrosol and oleuropein increased. The amount of total polyphenols and the antiradical capacity of the samples during in vitro digestion increased regardless of the presence and type of cyclodextrin (157,3 – 189,9 mg GAE / 100g increase). Characteristic olive pomace phenols were stable during the gastrointestinal digestion with the exception of oleuropein, that was completely degraded during intestinal phase. The presence of cyclodextrins in the olive pomace extracts negatively affected the dializability of biologically active compounds (reduction from 4,0% to 20,9%). Further studies in Caco-2 cell model or in vivo studies are needed to obtain a better insight into the stability and bioavailability of olive pomace phenols