Discovery of a tetrazole-thiourea derivative as a potential active agent against multidrug-resistant Staphylococcus aureus and Mycobacterium tuberculosis.

BACKGROUND

Rifampicin-resistant Mycobacterium tuberculosis (RR-TB) and methicillin-resistant Staphylococcus aureus (MRSA) underscore the need for new antibacterial chemotypes active across M. tuberculosis M. tuberculosis and Gram-positive pathogens. Both thiourea and tetrazole are well-established scaffolds in the scientific community for their promising antibacterial properties. The combination of tetrazole and thiourea moieties into a single molecular framework presents a promising strategy to overcome antimicrobial resistance.

METHODS

We designed and synthesized a series of tetrazole–thiourea derivatives (1–9) and a bis-tetrazole hybrid (10) through a one-step synthetic approach. Their antimicrobial potential was evaluated using a combination of in silico absorption, distribution, metabolism, excretion, and toxicity (ADMET) predictions, experimental lipophilicity determination (logD), and in vitro antibacterial assays against both reference and multidrug-resistant staphylococcal strains. Additionally, antitubercular activity was assessed against drug-sensitive, multidrug-resistant (MDR), and extensively drug-resistant (XDR) M. tuberculosis isolates. Molecular docking studies were performed to explore the binding interactions of the compounds with dihydrofolate reductase (DHFR) and penicillin-binding protein 4 (PBP4).

RESULTS

Compound 2, bearing a trifluoromethyl substituent, was the most potent. It achieved sub-µg/mL minimum inhibitory concentrations (MICs, 0.1–0.5 µg/mL) against staphylococci, comparable to ciprofloxacin, and maintained strong antitubercular activity (MIC = 0.5 µg/mL) across drug-sensitive, MDR, and XDR strains. Docking supported a dual-target mechanism involving DHFR and PBP4, providing a plausible rationale for its broad antibacterial efficacy. Despite higher lipophilicity within the series, compound 2 showed favorable ADMET predictions and experimental logD values in the developable range.

CONCLUSIONS

The tetrazole–thiourea scaffold, exemplified by compound 2, delivers dual efficacy against multidrug-resistant staphylococci and M. tuberculosis. These findings position compound 2 as a promising lead and a rational starting point for hit-to-lead optimization focused on potency–permeability balance and experimental confirmation of dual-target engagement.