Design and synthesis of quinazoline carboxylates against Gram-positive, Gram-negative, fungal pathogenic strains, and Mycobacterium tuberculosis

Aim: A novel series of ethyl 5-(4-substituted phenyl)-3-methyl-6,7,8,9-tetrahydro-5H-thiazolo[2,3- b ] quinazoline-2-carboxylate 3a-3j, were synthesized, characterized by spectral, elemental analyses and screened for their in vitro antibacterial and Mycobacterium tuberculosis (MTB) activities. Materials and Methods: The in vitro antibacterial and antifungal activities were determined by agar well-diffusion and cup-plate agar diffusion methods and the anti-tuberculosis (TB) screening for test compounds were evaluated against MTB H37Rv strain by Resazurin assay. Results: Among the derivatives tested, most of the compounds were found to have potent activity against microbial strains. The structure-activity relationship point of view, introduced group that enhance the lipophilicity as well ester, substituted aromatic ring at thiazole quinazoline nucleus showed increasing antimicrobial and anti TB activity. The high level of activity shown by the compounds with electron withdrawing groups in the para position on the benzene ring (3 g) suggests that these compounds could serve as leads for development of novel synthetic compounds with enhanced antibacterial and anti TB activities. Conclusion: These results provide a further insight into the structural requirements for targeting thiazolo quinazoline carboxylate to develop potential new agents to combat TB treatment.