Synthesis and antituberculosis activity of indole–pyridine derived hydrazides, hydrazide–hydrazones, and thiosemicarbazones

We describe the design, synthesis, and in vitro antimycobacterial activity of a series of novel simple hybrid hydrazides and hydrazide–hydrazones combining indole and pyridine nuclei. The compounds are derivatives of 1-acetylindoxyl or substituted indole-3-carboxaldehydes tethered via a hydrazine group by simple CN or double CN bonds with 3- and 4-pyridines, 1-oxide 3- and 4-pyridine carbohydrazides. The most active of 15 compounds showed MICs values against an INH-sensitive strain of Mycobacterium tuberculosis H37Rv equal to that of INH (0.05–2 μg/mL). Five compounds demonstrated appreciable activity against the INH-resistant M. tuberculosis CN-40 clinical isolate (MICs: 2–5 μg/mL), providing justification for further in vivo studies.

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