Synthesis, characterization and antioxidant activities of some α-lipoic acid derivative 1,3,4-thiadiazol compounds

In this study, synthesis, characterization and antioxidant activities of α-lipoic acid derivative thiadiazole compounds from 1,3,4-thiadiazole compounds, which have wide usage areas especially in industry, medicine and pharmacy, as in many fields of chemistry, were carried out. Compounds obtained from thiosemicarbazides by ring closure mechanism were diversified by attaching different substituents to the thiadiazole structure. The structure characterization of the compounds was evaluated by 1H-NMR, 13C-NMR and IR analyzes and physicochemical properties such as solubility, color and melting point of the compounds were demonstrated. Also, in this study, antioxidant activities of newly synthesized compounds were compared with the standard of α-lipoic acid, which is the starting molecule of the synthesis step, and ascorbic acid, a water-soluble antioxidant, using the 1,1-Diphenyl-2-Picryl Hydrazil (DPPH) free radical scavenging method. According to the calculated IC50 values, the antioxidant activities of the molecules followed the order, Ascorbic Acid > 5-(4- (1,2-dithiolan-3-yl)butyl)-N-(2-methoxyphenyl)-1,3,4-thiadiazol-2-amine > 5-(4- (1,2-dithiolan-3-yl)butyl)-N-(4-methylphenyl)-1,3,4-thiadiazol-2-amine > 5-(4-(1,2- dithiolan-3-yl)butyl)-N-phenyl-1,3,4-thiadiazol-2-amine > 5-(4-(1,2-dithiolan-3- yl)butyl)-N- methyl-1,3,4-thiadiazol-2-amine > 5-(4-(1,2-dithiolan-3-yl)butyl)-N methyl-1,3,4-thiadiazol-2-amine > N-(3-chlorophenyl)-5-(4-(1,2-dithiolan-3- yl)butyl)-1,3,4-thiadiazol-2-amine > N-cyclohexyl-5-(4-(1,2-dithiolan-3-yl)butyl)- 1,3,4-thiadiazol-2-amine > N-(2-chlorophenyl)-5-(4-(1,2-dithiolan-3-yl)butyl)- 1,3,4- thiadiazol-2-amine > Lipoic Acid