Click-chemistry-based multicomponent condensation approach for design and synthesis of spirochromene-tethered 1,2,3-triazoles as potential antitubercular agents

A series of spirochromene-tethered 1,2,3-triazoles (1,2,3-triazolylspirochromenes) were designed and synthesized via click-chemistry-based one-pot five-component reaction between N-propargyl isatins, malononitrile, dimedone (or 4-hydroxyl-6-methyl-2H-pyran-2-one), arylalkyl halides, and sodium azide using cellulose-supported CuI nanoparticles (Cell-CuI NPs) as heterogeneous catalyst. All synthesized compounds were screened for inhibitory activity against Mycobacterium tuberculosis H37Ra (ATCC 25177) and Mycobacterium bovis BCG (ATCC 35743), in active as well as dormant state. During screening, compounds 6h, j, l were found to exhibit promising antimycobacterial activity against M. bovis BCG, while compounds 7d, h, l showed promising antimycobacterial activity against M. tuberculosis H37Ra as well as M. bovis BCG. The active compounds were found to be noncytotoxic to three human cancer cell lines (MCF-7, HCT116, and A549). The active compounds exhibited selectivity index >10, indicating potential as antitubercular agents. The active compounds were also evaluated for in vitro antibacterial activity, with five (6h, l, 7b, f, l) showing good antibacterial activity against Gram-positive as well as Gram-negative bacteria. Compounds 6h, j, l exhibiting promising activity against M. bovis BCG can serve as good leads for further modification and optimization.