Fotosenzibilizovana oksidacija lipida u rastvoru indukovana kontinualnim UV-stresom u prisustvu kvercetina
Doktorand
Stanojević, Jelena S.Mentor
Cvetković, DraganČlanovi komisije
Cakić, MiloradŠmelcerović, Andrija
Zvezdanović, Jelena
Stanojević, Ljiljana
Metapodaci
Prikaz svih podataka o disertacijiSažetak
The aim of the present PhD thesis was to study UV(-A and -B)
induced lipid peroxidation sensitized by synthetic (benzophenone)
and endogenous photosensitizers (bilirubin, riboflavin) in the
presence of quercetin as antioxidant. Phospholipid mixure was used
as a ”protective target” and the whole process was followed in the
simplest possible system – methanolic solution.
Photodegradation of sensitizers and quercetin with the consequent
occurrence of their degradation products both individually and in the
mutual mixture, as well as in the mixture with phospholipids (where
beside the mentioned processes peroxides production occurs), was
followed by RP-HPLC chromatography. Unambiguous identification
of degradation products was enabled by UHPLC-ESI-MS technique
while free radical species were identified by EPR spectroscopy.
Benzophenone was photostabile, photodegradation of bilirubin gave
biliverdin and dipiroles while main degradation products of riboflavin
were lumichrome an...d lumiflavin. Insight into the mechanism and
control of lipid peroxidation provided ”conjugated diene” assay, by
following the signal at 234 nm (the absorption maximum of
conjugated diene structures). As typical Type I sensitizer,
benzophenone generated superoxide radical anion, while riboflavin
generated both superoxide and singlet oxygen by mixed Type I and II
mechanisms. Irradiation of bilirubin-riboflavin mixture showed, in the
indirect way, that bilirubin is typical Type II sensitizer.
Photosensitizing capability of the studied sensitizers decreases in the
order: riboflavin > benzophenone > bilirubin. Quercetin exhibited
efficient antioxidant activity, mediated by its own degradation, in
terms of its preventive (absorbing UV radition), chain-breaking
activities (scavenging of generated superoxide radical anion, singlet
oxygen and lipid peroxides) and besides all this effectively quenched
triplet exited states of sensitizers (first of all benzophenone and
riboflavin).
Fakultet:
Универзитет у Нишу, Технолошки факултет, ЛесковацDatum odbrane:
28-08-2017Projekti:
- Biljni i sintetički bioaktivni proizvodi novije generacije (RS-MESTD-Technological Development (TD or TR)-34012)