INSIGHTS INTO MYCOBACTERIAL ACTIVITY AND CYTOTOXICITY OF SUBSTITUED ISOXAZOLE-4-CARBOHYDRAZIDE DERIVATIVES.

The purpose of this study was to evaluate the antimycobacterial activity of novel derivatives of 5-amino-3-methyl-4-isoxazolecarboxylic acid hydrazide 1, isoniazid (INH) structural analogue. A set of 5-amino-3-methyl-4-isoxazolecarboxylic acid hydrazide 1 derivatives 2a-j have been obtained by condensation reactions with aldehydes and further transformed by cyclization with corresponding orthoesters to 5-amino-3-methylisoxazole[5,4-d]pyrimidin-4-one derivatives 3a-j and 4a-j. From the structural and functional point of view, all these products proved to be biologically important and could be used as substrates for further synthesis. 21 out of 31 structures were newly developed. Described compounds were screened against Mycobacterium fortuitum in MABA test. The most active compound 2e, 2g revealed minimum inhibitory concentration at 16 μg/ml. In addition, these compounds revealed low cytotoxicity against lung (A549) and fibroblasts (L929) cell lines. The results demonstrated the potential and importance of further development of 5-amino-3-methyl-4-isoxazolecarboxylic acid hydrazide derivatives as a new class of antimycobacterial compounds.