Synthesis, Antitubercular Activity, Molecular Modeling and Docking Studies of Novel Thiazolidin-4-One Linked Dinitrobenzamide Derivatives

Abstract

Background: Tuberculosis is a catastrophe sprawled across the world. The World Health Organization Global Tuberculosis Report 2017 inferred that there were an estimated 10.4 million people suffered from tuberculosis including 490000 Multidrug-Resistant TB (MDR-TB) cases. Several new lead molecules like dinitrobenzamide derivatives were found to be highly active against multidrugresistant strains of M. tuberculosis. To further explore the pharmacophoric space around the dinitobenzamide moiety, a series of compounds have been synthesized by linking it with the thiazolidin- 4-one. The presented work is an effort to study the biological effect of thiazolidin-4-one scaffold on dinitrobenzamide derivatives as antitubercular agents. A molecular modeling study was also performed on the synthesized molecules to reveal the requirements for further lead optimization. Methods: The thiazolidin-4-one linked 3,5-dinitrobenzamide derivatives have been synthesized by onepot three-component condensation reaction of an amine, substituted aldehydes and thioglycolic acid in presence of N, N'-Dicyclohexylcarbodiimide (DCC). These compounds were evaluated against Mycobacterium tuberculosis H37Ra. A pharmacophore modeling approach has been used in order to explore the collection of possible pharmacophore queries of thiazolidin-4-one linked 3, 5-dinitrobenzamide derivatives against M. tuberculosis. The synthesized compounds were docked on to the M. tuberculosis DprE1 enzyme to identify the structural features requirement of these analogs against this potential target of M. tuberculosis. Results: The synthesized compounds showed the antitubercular activity in the range of 6.25-50 μg/ml. The pharmacophore modeling suggests that the presence of aromatic moiety, thiazolidin-4-one ring and one of the nitro groups are significant for inhibiting the enzymatic activity. While docking studies showed that hydrophobic and hydrogen bond interactions of the aromatic moiety and nitro group crucial to inactivate the DprE1 enzyme. Conclusion: The study showed that the linking of thiazolidin-4-one with dinitrobenzamide leads to compounds active against M. tuberculosis. These findings also suggested that further lead optimization would be carried out by focusing on the aromatic system along with electron-rich substituents placed on the thiazolidin-4-one for making better hydrophobic and hydrogen bond interactions with the DprE1 target.