Determination of radical scavenging activities and reduction power properties of 2,3-dialkynilic thiophene derivatives

Free radicals are high energy unstable intermediates containing uncombined electrons.These products may also be present in compound form. Free radicals can cause liver diseases, especially cancer, as well as DNA and protein damage.The molecules that our body's defense system uses to neutralize free radicals are called antioxidants. In this thesis, radical scavenging activities and reducing power capacities of four different 2,3-dialkinylic thiophene derivatives of synthetic origin were tested with five different antioxidant capacity method. When the antioxidant capacities of tested derivatives were listed by considering the EC50 values in ABTS and galvinoxyl methods. While, it was determined that compound 4 > compound 2 > compound 1> compound 3 in ABTS assay and compound 4 > compound 3 > compound 1 > compound 2 in the galvinoxyl assay. However, the antioxidant capacities of the four different dialkilic thiophene derivatives were not determined as they did not react with DPPH radicals. Tested derivatives showed reduction activities in phosphomolybdenum and FRAP methods. When tested derivatives listed according to the reduction activies in phosphomolybdenum method, it was determined that compound 4 > compound 1 > compound 2 > compound 3. Consequently, in the FRAP method, two dialkinylic thiophene derivatives showed reduction activity by this method. These are compounds 4 and 2. Compound 4 (103.22 µM compound 4 showed 1.49 µM trolox equivanlent reducing activity) was found to be more active than compound 2 (128.03 µM compound 2 showed 0.34 µM trolox equivalent reducing activity). However, compound 1 and compound 3 did not show any reducing activities in FRAP method. Key words: Antioxidant, Antioxidant capacity, Thiophene derivatives.