Design, Synthesis, and Anti-Mycobacterial Evaluation of Triclosan-Isoniazid Hybrids.

A series of Triclosan-based hybrids and their Schiff base derivatives with isoniazid were designed through in silico modeling and synthesized using copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction. These compounds were then evaluated against both Mycobacterium tuberculosis (Mtb) and Mycobacterium abscessus (Mab). However, none of the synthesized hybrids exhibited significant growth inhibition, with minimum inhibitory concentration (MIC) values consistently exceeding 100 µg/mL. To further investigate these findings, we conducted mechanistic studies including thermogravimetric analysis (TGA) and UV-vis stability tests. TGA demonstrated thermal stability of the Schiff bases up to 270°C, while UV-vis analysis confirmed their chemical resilience across a wide pH spectrum, showing resistance to hydrolysis under acidic and basic conditions. The lack of observed antimicrobial activity may be attributed to the high lipophilicity of these molecules, as indicated by LogP values exceeding 5, which could limit their bioavailability. These findings suggest that although combining triclosan and isoniazid holds potential, further optimization of this hybrid strategy is necessary to improve efficacy.