Cationic amphipathic D-enantiomeric antimicrobial peptides with in vitro and ex vivo activity against drug-resistant Mycobacterium tuberculosis

Yun Lan, Jason T. Lam, Kit Hang Siu, Wing Cheong Yam, A. James Mason, Jenny K.W. Lam

Research output: Journal article publicationJournal articleAcademic researchpeer-review

30 Citations (Scopus)


Tuberculosis (TB) is the leading cause of bacterial death worldwide. Due to the emergence of multi-drug resistant TB (MDR-TB) and extensively drug-resistant TB (XDR-TB), and the persistence of latent infections, a safe and effective TB therapy is highly sought after. Antimicrobial peptides (AMPs) have therapeutic potential against infectious diseases and have the ability to target microbial pathogens within eukaryotic cells. In the present study, we investigated the activity of a family of six AMPs containing all-D amino acids (D-LAK peptides) against MDR and XDR clinical strains of Mycobacterium tuberculosis (Mtb) both in vitro and, using THP-1 cells as a macrophage model, cultured ex vivo. All the D-LAK peptides successfully inhibited the growth of Mtb in vitro and were similarly effective against MDR and XDR strains. D-LAK peptides effectively broke down the heavy clumping of mycobacteria in broth culture, consistent with a 'detergent-like effect' that could reduce the hydrophobic interactions between the highly lipidic cell walls of the mycobacteria, preventing bacteria cell aggregation. Furthermore, though not able to eradicate the intracellular mycobacteria, D-LAK peptides substantially inhibited the intracellular growth of drug-resistant Mtb clinical isolates at concentrations that were well tolerated by THP-1 cells. Finally, combining D-LAK peptide with isoniazid could enhance the anti-TB efficacy. D-LAK peptide, particularly D-LAK120-A, was effective as an adjunct agent at non-toxic concentration to potentiate the efficacy of isoniazid against drug-resistant Mtb in vitro, possibly by facilitating the access of isoniazid into the mycobacteria by increasing the surface permeability of the pathogen.
Original languageEnglish
Pages (from-to)678-689
Number of pages12
Issue number6
Publication statusPublished - 1 Dec 2014


  • Antimicrobial peptides
  • Clinical isolates
  • Isoniazid
  • Multi-drug resistant
  • THP-1
  • Tuberculosis

ASJC Scopus subject areas

  • Microbiology
  • Immunology
  • Microbiology (medical)
  • Infectious Diseases

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