Vrednotenje antioksidativne zaščite lipidov z nenasičenimi maščobnimi kislinami

Gagula, Hana (author), Mravljak, Janez (mentor)

Osnovni gradniki celičnih membran so fosfolipidi, ki tvorijo dvoslojno strukturo, s hidrofilnimi glavami, obrnjenimi proti vodnemu okolju, in hidrofobnimi repi, obrnjenimi v notranjost membrane. Takšna ureditev zagotavlja strukturno celovitost celične membrane in ločuje notranjost celic od zunanjega okolja. Fosfolipidi prav tako prispevajo k fluidnosti, prožnosti in prepustnosti membran. Če v svoji strukturi vsebujejo nenasičene maščobne kisline, z eno ali več dvojnimi vezmi, so dovzetni za oksidativni razpad skozi proces lipidne peroksidacije. Posledično pride do poškodb celice, kar lahko privede do razvoja bolezni. Liposomi so sferične strukture iz fosfolipidnih dvoslojev, ki se v zadnjih letih pogosto uporabljajo kot dostavni sistem na področjih farmacevtske in kozmetične industrije, ter kot sredstvo za preučevanje celičnih membran. Lahko jih uporabljamo kot modelne strukture za spremljanje antioksidativne zaščite antioksidantov, saj obstaja korelacija med antioksidativnim delovanjem snovi v liposomih in v bioloških membranah. Lipidno peroksidacijo v dvoslojih lahko preprečimo z uporabo lipofilnih antioksidantov. Flavonoidi so polifenoli rastlinskega izvora, ki lahko interagirajo s fosfolipidnimi dvosloji in skozi različne mehanizme izkazujejo antioksidativno delovanje. V okviru diplomske naloge smo pripravili liposome iz fosfolipida 1,2-di-(4Z,7Z,10Z,13Z,16Z,19Z-dokozaheksaenoil)-sn-glicero-3-fosfoholina – estra z dvema večkrat nenasičenima maščobnima kislinama. Pripravili smo liposome brez antioksidantov in liposome z različnimi koncentracijami flavonoidov: kvercetina, miricetina in miricitrina. Sprožili smo oksidacijo in analizirali vsebnost fosfolipida pred in po izpostavitvi kisiku z uporabo analizne metode tekočinske kromatografije ultra visoke ločljivosti sklopljene z detektorjem nabitih aerosolov. Ugotovili smo, da oksidacija lipida v liposomih brez antioksidanta poteče hitro. Dodani flavonoidi so izkazali različne ravni antioksidativne zaščite, ki je bila odvisna od vrste flavonoida in njegove koncentracije. Pri tem je miricitrin izkazal šibko, kvercetin pa relativno dobro antioksidativno delovanje, medtem ko je miricetin izstopal z izjemno visoko učinkovitostjo antioksidativne zaščite.

• Language: Slovenian
• Keywords: večkrat nenasičene maščobne kisline, lipidna peroksidacija, flavonoidi, antioksidanti, tekočinska kromatografija ultra visoke ločljivosti
• Work type: Bachelor thesis/paper
• Organization: FFA - Faculty of Pharmacy
• Year: 2024
• PID: 20.500.12556/RUL-160751-58812c24-2bef-2b9f-8fad-b28db6a5ca77
• Publication date in RUL: 04.09.2024

Secondary language

• Language: English
• Title: Evaluation of antioxidant protection of lipids with unsaturated fatty acids

Abstract

The basic building blocks of cell membranes are phospholipids, which form a bilayer structure, with hydrophilic heads facing the aqueous environment and hydrophobic tails facing the inside of the membrane. Such an arrangement ensures the structural integrity of the cell membrane and separates the cell interior from external environment. Phospholipids also contribute to the fluidity, elasticity and permeability of membranes. If they contain unsaturated fatty acids with one or more double bonds, they are susceptible to oxidative degradation through the process of lipid peroxidation. Consequently, this leads to cell damage, which can result in the development of diseases. Liposomes are spherical structures made of phospholipid bilayers, which in recent years have been widely used as a delivery system in the pharmaceutical and cosmetic industries, and as tools for studying cell membranes. They can be used as model structures to monitor the antioxidant protection of antioxidants, as there is a correlation between the antioxidant activity of compounds in liposomes and in biological membranes. Lipid peroxidation in bilayers can be prevented by using lipophilic antioxidants. Flavonoids are polyphenols of plant origin that can interact with phospholipid bilayers and exhibit antioxidant activity through various mechanisms. As part of the diploma thesis, we prepared liposomes using phospholipid 1,2-di-(4Z,7Z,10Z,13Z,16Z,19Z-docosahexaenoyl)-sn-glycero-3-phosphocholine – an ester with two polyunsaturated fatty acids. We prepared liposomes without antioxidants and liposomes with different concentrations of flavonoids: quercetin, myricetin and myricitrin. We initiated oxidation and analyzed phospholipid content before and after exposure to oxygen, using an ultra-high resolution liquid chromatography method coupled to a charged aerosol detector. We found that oxidation of lipid in liposomes without antioxidant takes place quickly. The added flavonoids exhibited different levels of antioxidant protection, depending on the type of flavonoid and its concentration. Here, myricitrin showed a weak and quercetin relatively good antioxidant activity, while myricetin stood out with an extremely high efficiency of antioxidant protection.

• Keywords: polyunsaturated fatty acids, lipid peroxidation, flavonoids, antioxidants, ultra-high resolution liquid chromatography