Synthesis and Antioxidant Activity of Some Thiazoles, Thiazolidinone, and Thiazolo[5,4-d]pyrimidine Derivatives

Various heterocyclic derivatives were obtained starting from ethyl 5-amino-2-(methylthio)thiazole-4-carboxylate. Antioxidant activity of the synthesized compounds was studied in vitro by using the DPPH test. The synthesized compounds showed absorption level of DPPH radicals in the 51.17–84.50% range. The most active 5-(hydrazinecarboxamido)-2-(methylthio)thiazole-4-carboxylate showed a remarkable scavenging activity (84.5%), followed by 5-(2-chloroacetamido)-2-(methylthio)thiazole-4-carboxylate, which showed scavenging activity of 66.28%. The remarkable activity of hydrazinecarboxamido-derivative could be attributed to the presence of hydrazine group in its structure which can donate a hydrogen atom to the DPPH radical.