Development of potent nanosized isatin-isonicotinohydrazide hybrid for management of Mycobacterium tuberculosis.

Inspired by the antitubercular activity of isoniazid (INH) and 5-bromoisatin, isatin-INH hybrid (WF-208) has been synthesized as a potent agent against multidrug-resistant (MDR) and extensively drug-resistant (XDR) strains of M. tuberculosis. In silico molecular docking studies indicated that DprE1, a critical enzyme in the synthesis of M. tuberculosis cell wall, is a potential enzymatic target for WF-208. The synthesized WF-208 was incorporated into a nanoparticulate system to enhance stability of the compound and to sustain its antimicrobial effect. Nanosized spherical niosomes (hydrodynamic diameter of ca. 500-600 nm) could accommodate WF-208 at a high encapsulation efficiency of 74.2%, and could impart superior stability to the compound in simulated gastric conditions. Interestingly, WF-208 had minimal inhibitory concentrations (MICs) of 7.8 and 31.3 µg/mL against MDR and XDR M. tuberculosis, respectively, whereas INH failed to demonstrate bacterial growth inhibition at the range of the tested concentrations. WF-208-loaded niosomes exhibited a 4-fold increase in the anti-mycobacterial activity as compared to the free compound (MIC of 1.9 vs. 7.8 µg/mL) against H37Rv M. tuberculosis, after three weeks of incubation with WF-208-loaded niosomes. Incorporation of the compound into nanosized vesicles allowed for a further increase in stability, potency and sustainability of the anti-mycobacterial activity, thus, providing a promising strategy for management of tuberculosis.