Title
Stabilnost hlorofila na oksidacioni stres u vodenom medijumu i u lipozomima
Creator
Petrović, Sanja 1985-
Copyright date
2016
Object Links
Select license
Autorstvo-Nekomercijalno-Bez prerade 3.0 Srbija (CC BY-NC-ND 3.0)
License description
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Language
Serbian
Cobiss-ID
Theses Type
Doktorska disertacija
description
Datum odbrane: 02.03.2016.
Other responsibilities
mentor
Zvezdanović, Jelena
mentor
Anđelković, Tatjana
mentor
Cvetković, Dragan
Academic Expertise
Tehničko-tehnološke nauke
University
Univerzitet u Nišu
Faculty
Tehnološki fakultet
Group
Katedra za hemijske nauke
Alternative title
Stability of chlorophyll on oxidative stress in water medium and in liposomes
Publisher
[S. Petrović]
Format
182 listova
description
Chemistry and chemical technology
Abstract (en)
The stability of chlorophyll on chosen oxidative stresses in disorganized aqueous
medium and more organized liposomal structures is a topic of this doctoral thesis. The unique
role of chlorophyll, based on its specific and very diverse chemical reactivity justifies its
application in industrial technologies, food processing and pharmaceutical and cosmetic
industry as well as in medicine. The question about chlorophyll stability is set as one of the
preconditions for its potential applications in various areas of science and technology. In vitro
oxidative stresses applied to the chlorophyll are: chemical oxidation by Fenton reagent and
thermal initiator, enzyme catalyzed oxidation and photo-oxidation by continuous visible and
UV-B irradiation. The stability of chlorophyll in the aqueous medium after oxidative stress
was studied using absorption spectroscopy while the corresponding changes in the structure
of Chl-molecules was followed by electro-spray mass spectrometry combined with UHPLC
chromatography, in order to get the possible insight into the degradation-oxidation
mechanisms. Changes in the physical conditions of the liposome interior (organized lipid
structures), which affect the behavior of incorporated chlorophyll penetration and therefore a
different degradation degree, were investigated using absorption and fluorescence
spectroscopy. In addition to the presented methods, in order to evaluate some of the possible
mechanisms involved in oxidative stress, two peroxide tests were performed: test of
conjugated dienes and TBA-MDA test.
The results show that the stability of chlorophyll depends not only on chlorophyll
concentration but also the nature of the applied oxidative stress. Generally, the chlorophyll in
liposomes, the same as in the aqueous medium, shows a low stability degree, which resulted
in its modifications, creating oxidation-degradation products. The destructiveness of the
applied oxidative stresses on chlorophyll could be ranked as follows: the effect of Fenton
reagent < effect of the thermal initiator < VIS < UV-B radiation, at precisely defined
conditions. Chlorophyll is more stable in liposome dispersions, which supports the
conclusion that it is better to keep it in liposomes than in water.
xiv
Based on these results it can be concluded that the more accurate knowledge of the
chlorophyll behavior under the oxidative stress, as well as its optimal concentration and
stability in the potential formulations, is crucial to its further use.
Authors Key words
Hlorofil; Stres; Oksidacija; Stabilnost
Authors Key words
Chlorophyll; Stress; Oxidation; Stability
Classification
547.979.7+547.953:543.422
Type
Elektronska teza
Abstract (en)
The stability of chlorophyll on chosen oxidative stresses in disorganized aqueous
medium and more organized liposomal structures is a topic of this doctoral thesis. The unique
role of chlorophyll, based on its specific and very diverse chemical reactivity justifies its
application in industrial technologies, food processing and pharmaceutical and cosmetic
industry as well as in medicine. The question about chlorophyll stability is set as one of the
preconditions for its potential applications in various areas of science and technology. In vitro
oxidative stresses applied to the chlorophyll are: chemical oxidation by Fenton reagent and
thermal initiator, enzyme catalyzed oxidation and photo-oxidation by continuous visible and
UV-B irradiation. The stability of chlorophyll in the aqueous medium after oxidative stress
was studied using absorption spectroscopy while the corresponding changes in the structure
of Chl-molecules was followed by electro-spray mass spectrometry combined with UHPLC
chromatography, in order to get the possible insight into the degradation-oxidation
mechanisms. Changes in the physical conditions of the liposome interior (organized lipid
structures), which affect the behavior of incorporated chlorophyll penetration and therefore a
different degradation degree, were investigated using absorption and fluorescence
spectroscopy. In addition to the presented methods, in order to evaluate some of the possible
mechanisms involved in oxidative stress, two peroxide tests were performed: test of
conjugated dienes and TBA-MDA test.
The results show that the stability of chlorophyll depends not only on chlorophyll
concentration but also the nature of the applied oxidative stress. Generally, the chlorophyll in
liposomes, the same as in the aqueous medium, shows a low stability degree, which resulted
in its modifications, creating oxidation-degradation products. The destructiveness of the
applied oxidative stresses on chlorophyll could be ranked as follows: the effect of Fenton
reagent < effect of the thermal initiator < VIS < UV-B radiation, at precisely defined
conditions. Chlorophyll is more stable in liposome dispersions, which supports the
conclusion that it is better to keep it in liposomes than in water.
xiv
Based on these results it can be concluded that the more accurate knowledge of the
chlorophyll behavior under the oxidative stress, as well as its optimal concentration and
stability in the potential formulations, is crucial to its further use.
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