Antioxidant properties of certain C5 substituted 4-arylimino-thiazolidin-2-ones

Abstract

Aim. Expanding the synthetic potential of 4-arylimino-thiazolidin-2-ones; a study of reactivity; and primary screening for antioxidant activity of synthesized compounds. Materials and Methods. All chemicals were of analytical grade and commercially available. When performing the synthetic part of the work, reagents manufactured by Merck (Germany) and Sigma-Aldrich (USA) were used. All the reagents and solvents were used without further purification and drying. Methods of organic synthesis, physical and physical-chemical methods of analysis of organic compounds (NMR spectroscopy, elemental analysis) were used in the study. Results and Discussions. The peculiar pharmacological activities of 4-iminothiazolidin-2-ones prompted us to synthesize certain С5 substituted 4-arylimino-thiazolidin-2-ones and test them for antioxidant activity. The specified scaffold represents a convenient intermediate in order to afford С5 substituteds 4-arylimino-thiazolidin-2-ones. The active methylene group presence in C5 position of the basic scaffold provides an entry for its utilization in azo coupling and aldol condensation reactions leading to appropriate 5-aryl-hydrazono and 5-arylidene derivatives of 4-arylimino-thiazolidin-2-one generation. The structures of the obtained compounds were confirmed by 1H NMR spectroscopy and elemental analysis. The spectroscopic data of all compounds correspond to the proposed structures. The antioxidant activity of the synthesized compounds was measured in vitro by the method of scavenging effect on 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals. DPPH radical found many applications due to its high stability in a methanolic solution and intense purple color. In its oxidized form, the DPPH radical has an absorbance maximum at a wavelength of 517 nm. For the first time, antioxidant activity was identified among С5 substituted 4-arylimino-thiazolidin-2-ones. Conclusions. Based on azo coupling and aldol condensation reactions, structural modification of the C5 position of certain 4-arylimino-thiazolidin-2-ones was conducted. For all synthesized compounds, primary pharmacological screening for antioxidant activity was performed. Three highly active compounds with a pronounced antioxidant effect have been identified, which approach or exceed ascorbic acid in terms of activity. Key words: organic synthesis, 4-arylimino-thiazolidin-2-ones, 2,2-diphenyl-1-picrylhydrazyl, antioxidant activity