Antibacterial and anti-TB tat-peptidomimetics with improved efficacy and half-life.

Non-natural antimicrobial peptides are ideal as next-generation antibiotics because of their ability to circumvent the problems of drug resistance and in vivo instability. We report novel all-α- and α,γ-mixed Tat peptide analogues as potential antibacterial and anti-TB agents. These peptides have broad spectrum antibacterial activities against Gram-positive (MICs 0.61 ± 0.03 to 1.35 ± 0.21 μM with the peptide γTatM4) and Gram-negative (MICs 0.71 ± 0.005 to 1.26 ± 0.02 μM with γTatM4) bacteria and are also effective against active and dormant forms of Mycobacterium tuberculosis, including strains that are resistant to rifampicin and isoniazid. The introduction of the non-natural amino acids of the study in the Tat peptide analogues results in increased resistance to degradation by proteolysis, significantly increasing their half-life. The peptides appear to inhibit bacteria by a membrane disruption mechanism, and have only a low cytotoxic effect on mammalian cells.