Synthesis, structure, ADME and biological activity of three 2,6-disubstituted thiosemicarbazone derivatives.

Three new 2,6-disubstituted thiosemicarbazone derivatives of pyridine, namely, 2-{amino[6-(pyrrolidin-1-yl)pyridin-2-yl]methylidene}-N,N-dimethylhydrazine-1-carbothioamide, C 13 H 20 N 6 S, 2-{amino[6-(piperidin-1-yl)pyridin-2-yl]methylidene}-N,N-dimethylhydrazine-1-carbothioamide, C 14 H 22 N 6 S, and 2-[amino(6-phenoxypyridin-2-yl)methylidene]-N,N-dimethylhydrazine-1-carbothioamide monohydrate, C 15 H 17 N 5 OS·H 2 O, have been synthesized and characterized by NMR spectroscopy and low-temperature single-crystal X-ray diffraction. In addition, their antibacterial and anti-yeast activities have been determined. The ability of the tested compounds to inhibit bacterial growth was comparable to vancomycin as a reference drug. Compared to isoniazid (MIC 0.125 and 8 µg ml -1 ), the compounds showed the ability to inhibit the growth of Mycobacterium tuberculosis to a moderate degree for the standard strain and at the same level or higher (MIC 4-8 µg ml -1 ) for the resistant strain. All three compounds adopt the zwitterionic form in the crystal structure regardless of the presence or absence of solvent molecules.