Mehanizmi bioloških efekata jedinjena dobijenih alkalnom hidrolizom jabučnog pektina

Abstract

Jabuka (Malus domestica Borkh) je od davnina poznata po svojim pozitivnim nutritivnim i lekovitim svojstvima pa je njen hemijski sastav intenzivno proučavan. Za pektin iz jabuka, kao i iz drugih izvora npr. citrusnog voća, je poznato da pozitivno utiče na gastrointestinalni trakt, dominantno putem uticaja na gastrointestinalnu mikrobiotu. Pretpostavka je da se taj uticaj uglavnom ostvaruje preko njegove polimerne strukture i slabe rastvorljivosti. Mi smo derivatizovali pektin primenom alkalne hidrolize u prisustvu vodonik peroksida. Dobijeni proizvod okarakterisali smo FTIR spektroskopijom i pokazali da u odnosu na polazni materijal ima simetrične i asimetrične vibracije istezanja karboksilatnih grupa. Ovo indukuje mogućnost da dobijeni derivat ima specifične reakcije sa hidroksilnim radikalima koji nastaju u Fentonovoj reakciji in vitro, a uslovi za postojanje Fentonove reakcije in vivo postoje u gastrointestinalnom traktu u prisustvu Fe i vitamina C. Ispitivanja EPR spektroskopijom pokazala su da derivat jabučnog pektina u sistemu Fentonove reakcije podstiče stvaranje ugljen-dioksid radikalskog anjona (•CO2 - radikala) umesto hidroksidnog radikala. Za ovaj radikal su prethodna ispitivanja pokazala da ima duži poluživot od hidroksidnog radikala i da specifično reaguje sa određenim proteinima. To ukazuje na mogućnost da derivat pektina koji smo mi dobili u gastrointestinalnom traktu ima dodatno pozitivne efekte putem direktnog uticaja na mikrobiotu. Stoga smo ispitali antimikrobnu aktivnost pektina i njegovih derivata i pokazali, da derivati pektina dobijeni alkalnom hidrolizom jabučnog pektina (APDO) sprečavaju rast Saccharomyces cerevisiae i Candide albicans, dok nemaju uticaj na rast Escherichia coli i Staphylococcus aureus...

Apple (Malus domestica Borkh) has long been known for its positive nutritive and medical properties, so its chemical composition has been intensively studied. For apple pectin, as well as from other sources e.g. citrus fruit, is known that have positive effect on gastrointestinal tract, predominantly through the influence to gastrointestinal microbiota. The assumption is that this effect is mainly achieved through its polymeric structure and poor solubility. We have derivatized pectin using alkaline hydrolysis in the presence of hydrogen peroxide. The obtained product was characterized by FTIR spectroscopy and showed symmetric and asymmetric stretching vibrations of the carboxylate groups in comparing with the starting material. This induces the possibility that the resulting derivative has specific reactions with the hydroxyl radicals formed in the Fenton reaction in vitro, and the conditions for the existence of a Fenton reaction in vivo exist in the gastrointestinal tract in the presence of Fe and vitamin C. EPR spectroscopy studies have shown that the apple pectin derivative in the Fenton reaction system induces the formation of carbon dioxide radicals anion (•CO2 - radicals) instead of hydroxyl radicals. Preliminary studies for this radical have shown that it has a longer half-life than hydroxyl radicals and specifically reacts with certain proteins. This indicates the possibility that the pectin derivative that we get has additional positive effects in the gastrointestinal tract through the direct impact on the microbiota. Therefore, we examined antimicrobial effect of pectin and its derivatives and showed that the pectin derivatives obtained by alkaline hydrolysis of apple pectin (APDO) inhibited the growth of Saccharomyces cerevisiae and Candide albicans and had no influence on the growth of Escherichia coli and Staphylococcus aureus. We also analyzed the effects of pectin derivatives (apple and citrus) and oligosaccharides derived from polygalacturonic acid (APDO, CPDO and PGDO) on the growth of one Gram-negative representative strain of Escherichia coli ATCC 25922 and one Gram-positive representative strain of Staphylococcus aureus in the presence of substances that imitate conditions in a gastrointestinal tract that favors the Fenton reaction...