master's thesis
Sinergističko - antagonistički utjecaj izomera vitamina E na kinetiku nestanka DPPH radikala u uljima ekstrahiranih iz koštica grožđa (Cabernet sauvignon i Cabernet franc)

Lidija Šimić (2016)
Sveučilište u Rijeci
Medicinski fakultet
Katedra za kemiju i biokemiju
Metadata
TitleSinergističko - antagonistički utjecaj izomera vitamina E na kinetiku nestanka DPPH radikala u uljima ekstrahiranih iz koštica grožđa (Cabernet sauvignon i Cabernet franc)
AuthorLidija Šimić
Mentor(s)Dalibor Broznić (thesis advisor)
Abstract
U ovom istraživanju ispitivano je međudjelovanje pojedinih izomera vitamina E (α-, γ- i δ-tokoferol) dodanih u različitim volumenima i kombinacijama iz standardnih otopina i izomera ekstrakta vitamina E dobivenog iz ulja koštica grožđa dvaju sorti, Cabernet sauvignon (uzorak CS) i Cabernet franc (uzorak CF) s područja Slavonije. Također analiziran je i utjecaj izomera na brzinu reakcije s radikalima te uključenost izomera u pojedine faze brzine kemijske reakcije. U ekstrakte vitamina E dodani su određeni volumeni standardnih otopina pojedinih izomera α-, γ- i δ-tokoferola i to u različitim kombinacijama (prva tri uzorka sadržavala su samo po jedan izomer, četvrti, peti i šesti sadržavali su kombinacije dvaju izomera dok je posljednji sedmi sadržavao kombinaciju sva tri izomera). Antioksidacijska aktivnost uzoraka prikazana je gubitkom signala DPPH radikala u odnosu na koncentraciju izračunatom metodom TEAC („Trolox equivalent antioxidant capacity“). Rezultati ukazuju da porastom udjela antioksidansa raste i antioksidativna aktivnost. Nadalje utvrđeno je da kombinacije dodanih α, γ- i δ-tokoferola u ekstrakt vitamina E iz ulja CS i CF imaju antagonistički utjecaj osim uzorka CS6 u kojem je dodana kombinacija izomera γ- i δ-tokoferola. Za opisivanje kinetike nestanka radikala korišteno je pet monofaznih i bifaznih matematičkih modela. Dobiveni rezultati pokazali su da se reakcija odvija u dva stupnja, brža reakcija u početnih 4 do 6 minuta, nakon čega slijedi sporija i monotonija reakcija. Na osnovu dobivenih rezultata može se zaključiti da je bifazna kinetika nestanka DPPH radikala posljedica niza složenih reakcija koje se odvijaju različitim mehanizmima, a u kojima sudjeluju pojedini izomeri tokoferola.
KeywordsVitamin E tocopherols TEAC DPPH radical kinetics mathematical models
Committee MembersIvana Gobin (committee chairperson)
Marin Tota (committee member)
Dalibor Broznić (committee member)
GranterSveučilište u Rijeci
Medicinski fakultet
Lower level organizational unitsKatedra za kemiju i biokemiju
PlaceRijeka
StateCroatia
Scientific field, discipline, subdisciplineBIOMEDICINE AND HEALTHCARE
Basic Medical Sciences
Medical Biochemistry
Study programme typeuniversity
Study levelgraduate
Study programmeStudy of Sanitary Engineering
Academic title abbreviationmag. sanit. ing.
Genremaster's thesis
Language Croatian
Defense date2016-07-22
Parallel abstract (English)
In the present study the effects and interactions of α-, γ- and δ-tocopherols added into the vitamin E extract obtained from the two oil grape seeds cultivars (Cabernet sauvignon, CS; Cabernet franc, sample CF) were examined. α-, γ- and δ-tocopherols were added at different volumes and combinations from the standard tocopherol solutions. The effect of tocopherol isomers on the rate of chemical reaction with radicals as well as involvement of individual tocopherol isomers in different phases of the chemical reaction were analyzed. At the vitamin E extracts, α-, γ- and δ-tocopherol standard solutions at different volumes and combinations were added, the three samples contained only the one of the isomer, the other three contained the combination of two isomers and last one contained the combinations of all three isomers. The antioxidant sample activity was shown by losing the signal of DPPH radical in the relation to the concentration calculated from TEAC method („Trolox equivalent antioxidant capacity“). The results indicate that the increasing antioxidants amount , increase the antioxidant activity of the sample. Furthermore, it was found that the combinations of α-, γ- and δ-tocopherol solutions added into the vitamin E of CS and CF extracts, showed the antagonistic effect, except for the sample CS6 where a combination of γ- and δ-tocopherol isomers was added. For description of the radical disappearance kinetics five mathematical models (mono- and biphasic) were used. The results showed that the reaction takes place in the two phases; first rapid phase during the initial 4 – 6 minutes of the reaction when follow the second much slower and monotonus phase. Results of the study pointed that the biphasic kinetics of DPPH disappearance is a consequence of the complexity of reactions that involve different tocopherol isomers and proceed through different chemical pathways.
Parallel keywords (Croatian)vitamin E tokoferoli TEAC DPPH radikal kinetika matematički modeli
Resource typetext
Access conditionAccess restricted to students and staff of home institution
Terms of usehttp://rightsstatements.org/vocab/InC/1.0/
URN:NBNhttps://urn.nsk.hr/urn:nbn:hr:184:818809
CommitterBosa Licul