Relationships Between the Chemical Structure of Substances and Their Antimycobacterial Activity Against Atypical Strains. Part 18. 3-Phenyl-2H-1,3-benzoxazine-2,4(3H)-diones and Isosteric 3-Phenylquinazoline-2,4(1H,3H)-diones

A series of 3-phenyl-2 H -1,3-benzoxazine-2,4(3 H )-diones 2 and 3-phenylquinazoline-2,4(1 H ,3 H )-diones 5 substituted on the phenyl rings were synthesized. The target compounds as well as the intermediates were tested against Mycobacterium tuberculosis, M. kansasii , and M. avium . The replacement of the oxygen atom by nitrogen resulted in a decrease or loss of antimycobacterial activity. 2-[(Ethoxycarbonyl)amino]benzanilides 4 appeared to be inactive. Salicylanilides 1 and 3-phenyl-2 H -1,3-benzoxazine-2,4(3 H )-diones 2 exhibit significant activity against both M. tuberculosis and nontuberculous mycobacteria (the MICs within the range of 4-250 μmol/l for all compounds). The antimycobacterial activity of the compounds increases with increasing both electron-withdrawing properties and hydrophobicity of the substituent(s) on the phenyl moiety. The antimycobacterial profile of the compounds was analyzed according to the criteria based on vector algebra, such as cosine coefficients. Moreover, salicylanilides 1 exhibit activity against other microorganisms tested by the agar diffusion method.