Synthesis and Antioxidant Properties of Pyrazine-Thiazole Bi-heteroaryl Compounds

In order to find novel pyrazine- and thiazole-based derivatives with potent antioxidant properties, eight pyrazine-thiazole bi-heteroaryl compounds were designed and prepared via active group splicing method between pyrazine-Noxides and thiazoles. They were structurally characterized by H-1 NMR, C-13 NMR, IR, and HPLC-MS. Antioxidant abilities of the obtained compounds were evaluated by inhibiting radicals induced oxidation of DNA and quenching radicals. The results showed that eight compounds can effectively inhibit radicals induced oxidation of DNA and quench radicals, which revealed that the compounds have strong radical scavenging properties and reduction ability, and can be potential antioxidants. The effective measurement factor (n) values of these compounds ranged from 1.48 to 2.12 in 2,2-azobis(2-amidinopropanehydrochloride) (AAPH) induced oxidation of DNA. The absorbance percentages of eight compounds to the blank thiobarbituric acid reactive substance (TBARS percentage) were 54.3%similar to 76.1% and 55.4%similar to 68.3% in inhibiting HO center dot and glutathione radical (GS center dot) induced oxidation of DNA, respectively. Eight compounds can scavenge 2,2-azinobis(3-ethylbenzothiazoline-6-sulfonate) cationic radical (ABTS center dot) and 2,2-diphenyl-1-picrylhydrazyl radical (DPPH center dot). In addition, it was found that the antioxidant activity of pyrazine-thiazole bi-heteroaryl compounds was significantly higher than that of pyrazine-oxazole bi-heteroaryl compound.