Digestomika alergena kikirikija i karakterizacija fragmenata otpornih na proteolizu

Abstract

INFOGEST metoda predstavlja standardizovani protokol za in vitro simulacijudigestije kompletne hrane, zasnovanom na fiziološki relevantnim uslovima. Predmetrada ove disertacije je ispitivanje digestibilnosti alergena kikirikija iz celog zrnaprimenom INFOGEST metode, kao i karakterizacija njihovih fragmenata otpornih naproteolizu.Za odstranjivanje lipida primenjena je metoda taloženja proteina, koja se pokazala kaosuperiornija u odnosu ekstrakciju lipida organskim rastvaračem, usled manjegkvalitativnog i kvantitativnog gubitka proteina.U ovoj tezi je pokazano da termički tretmani kikirikija, pored matriksa hrane, dodatnootežavaju oslobađanje proteina iz zrna, što čini glavne alergene kikirikija Ara h 1, Ara h2 Ara h 3 i Ara h 6 nedostupnijim za pepsinsku hidrolizu. Oslobađanje proteinakikirikija, kao i digestibilnost, u gastričnoj fazi se pokazala znatno izraženijom, uodnosu na intestinalnu fazu, s tim da je digestija kod pečenog kikirikija otežana uodnosu na sirovi. Nakon oralno-gastrične digestije celog zrna sirovog kikirikija, glavnialergeni kikirikija u velikoj meri ostaju intaktni, a njihovi peptidi otporni na digestijuzadržavaju alergeni kapacitet. Pokazano je da većina Ara h 2 i Ara h 6 alergena ostajerezistentna na digestiju. Ara h 1 i Ara h 3 kaskadno podležu pepsinolizi, do fragmenatakoji i dalje zadržavaju IgE vezujući potencijal. Mali peptidi koji potiču od Ara h 2alergena, su se pokazali kao najpotentniji inhibitori vezivanja IgE iz seruma pacijenataalergičnih na kikiriki, u odnosu na male Ara h 1 i Ara h 3 peptide.U ovoj disertaciji je pokazana izuzetno važna uloga efekata matriksa hrane, kao i njenetermičke obrade, na digestiju proteina hrane, koji mogu povećati stabilnost alergenahrane tokom digestije, i time omogućiti zadržavanje potencijala aktivacije alergijskereakcije nakon oralno-gastrične faze digestije.

INFOGEST method is standardized protocol for in vitro simulation of complete fooddigestion, based on physiologicaly relevant conditions. The objective of thisdissertation was to investigate digestibility of peanut allergens from whole peanutkernel by INFOGEST method, as well as to characterize their fragments resistant toproteolysis.For delipidation, protein precipitation approach was applied, showing to be superior incomparison to delipidation by organic solevent, due to lower qualitative andquantitative protein loss.In this thesis it was shown that peanut thermal processing, in addition to effect of foodmatix, further complicates the extractability and digestibility of proteins from the grain,making peanut allergens Ara h 1, 2, 3 and 6, less accessible for pepsin hydrolysis.Extractability and digestibility of peanut proteins in the gastric phase have shown to besignificantly more pronounced, in comparison to intestinal phase, and roasted peanutdigestion was impaired compared to the raw. It was shown that after oral and gastricdigestion of whole raw peanut grains peanut allergens largely remain intact, and theirdigestion resistant peptides retain allergenic capacity. The most Ara h 2 and Ara h 6allergens have been shown to remain resistant to digestion. Ara h 1 and Ara h 3undergo pepsinolysis with cascade pattern to consequently smaller peptide fragmentswith retained IgE binding capacity. Small peptides from Ara h 2 allergens were themost potent inhibitors of IgE binding from sera of peanut allergic patients, compared tosmall peptides from Ara h 1 and Ara h 3.This thesis points to the great importance of the effects of food matrix, as well as foodthermal processing, on protein digestibility, which can create additional stability offood allergens during digestion, and thus enable retaining of their potential for thesensitization or triggering of allergic reactions.