{Pi}-{Pi} Interactions Stabilize PeptoMicelle-Based Formulations of Pretomanid Derivatives Leading to Promising Therapy Against Tuberculosis in Zebrafish and Mouse Models

Abstract

Tuberculosis is the deadliest bacterial disease globally, threatening the lives of millions every year. New antibiotic therapies that can shorten the duration of treatment, improve cure rates, and impede the development of drug resistance are desperately needed. Here, we used polymeric micelles to encapsulate four second-generation derivatives of the antitubercular drug pretomanid that had previously displayed much better in vivo activity against Mycobacterium tuberculosis than pretomanid itself. Because these compounds were relatively hydrophobic, we expected that such micellar formulations would increase drug bioavailability, reduce toxicities, and improve therapeutic outcomes. The polymeric micelles were based on polypept(o)ides (PeptoMicelles) and were stabilized in their hydrophobic core by {pi}-{pi} interactions, allowing the efficient encapsulation of aromatic pretomanid derivatives. The stability of these {pi}-{pi}-stabilized PeptoMicelles was demonstrated in water, blood plasma, and lung surfactant by fluorescence cross-correlation spectroscopy and was further supported by prolonged circulation times of several days in the vasculature of zebrafish larvae. The pretomanid derivative with the best in vitro potency against Mycobacterium marinum ("drug D") was also the most efficacious PeptoMicelle formulation tested in the zebrafish larvae infection model, almost completely eradicating the bacteria at non-toxic doses. This lead formulation was further assessed against Mycobacterium tuberculosis in the susceptible C3HeB/FeJ mouse model, which develops human-like necrotic granulomas. Following intravenous administration, the drug D micellar formulation significantly reduced bacterial burden and inflammatory responses in the lungs and spleens of infected mice.