Tez özetleri Astronomi ve Uzay Bilimleri Anabilim Dalı

Synthesis, Characterization and Investigation of Antioxidant Capacity

of Some Flavanon-Oxime Compounds
Naringin (4’,5,7-Trihydroxyflavanone-7-rutinoside) (N) is a flavanone glycozide. It is a major flavonoid in grapefruit and gives the grapefruit juice its bitter taste. Naringenin (4’,5,7-Trihidroksiflavanone) (NG) is one of the most abundant citrus and grapefruit polyphenolics which is the aglycone of naringin. Flavanone oximes were used in the synthesis of anticancer and radioprotector compounds having antiradical activity. The aim of this thesis work is to synthesize and investigate the corresponding oximes of NG and N, naringenin oxime (NG-Ox) and naringin oxime (N-Ox). The structure of synthesized compounds (NG-Ox and N-Ox) were characterized by FT-IR, ¹H-NMR and elemental analysis. Synthesized oxime compounds (N-Ox and NG-Ox) and their starting materials (N and NG) were analysed together by HPLC method and these compounds showed to have diffirent retention times. Synthesized compounds were screened for their antioxidant capacities by using the spectrophotometric “cupric reducing antioxidant capacity” (CUPRAC) method which originally developed in our department. The measurement of TEAC (trolox equivalent antioxidant capacity) coefficients were based on the oxidation of these compounds to the corresponding quinones by the chromogenic copper(II)-neocuproine (Cu(II)-Nc) reagent, which was itself reduced to the cuprous neocuproine chelate showing maximum absorbance at 450 nm wavelength. The TEAC coefficients of N, NG and their oximes with respect to the normal CUPRAC method were found in the following order; 0.02, 0.52, 0.05 and 1.80 and with respect to the incubated CUPRAC method were found in the following order; 0.13, 4.70, 2.28 and 7.12. The theoretical and the experimentally found total antioxidant capacity (TAC) values of complex mixtures in different concentrations (including N, NG, their oxime compounds) were compared to prove additivity of CUPRAC method. In this thesis; other parameters of scavenging activity effects (^.OH, O₂^•−, and H₂O₂) of N, NG, and their oximes were also determined. % HRS activities of mentioned compounds were; 79.9, 81.5, 71.3, 73.5; % SRSA activities were; 4.79, 6.77, 12.2, 8.9 and % HPS activities were; 3.3, 26.04, 18.6, 11.5 respectively.