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Open Access Research article

Supramolecular assemblies of rifampicin and cationic bilayers: preparation, characterization and micobactericidal activity

Lilian Barbassa12, Elsa M Mamizuka2 and Ana M Carmona-Ribeiro12*

Author Affiliations

1 Biocolloids Lab, Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, CP 26077, CEP 05513-970, São Paulo SP, Brazil

2 Departmento de Análises Clínicas e Toxicológicas, Faculdade de Ciências Farmacêuticas, Universidade de São Paulo, CEP 05508-900, São Paulo/SP, Brazil

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BMC Biotechnology 2011, 11:40  doi:10.1186/1472-6750-11-40

Published: 15 April 2011

Abstract

Background

Cationic bilayers based on the inexpensive synthetic lipid dioctadecyldimethylammonium bromide (DODAB) have been useful as carriers for drug delivery, immunoadjuvants for vaccines and active antimicrobial agents.

Methods

Rifampicin (RIF) or isoniazid (ISO) interacted with DODAB bilayer fragments (BF) or large vesicles (LV). Dispersions were evaluated by dynamic light-scattering for zeta-average diameter (Dz) and zeta-potential (ζ) analysis; dialysis for determination of drug entrapment efficiency; plating and CFU counting for determination of cell viability of Mycobacterium smegmatis or tuberculosis, minimal bactericidal concentration (MBC) and synergism index for DODAB/drug combinations.

Results

DODAB alone killed micobacteria over a range of micromolar concentrations. RIF aggregates in water solution were solubilised by DODAB BF. RIF was incorporated in DODAB bilayers at high percentiles in contrast to the leaky behavior of ISO. Combination DODAB/RIF yielded MBCs of 2/2 and 4/0.007 μg/mL against Mycobacterium smegmatis or Mycobacterium tuberculosis, respectively. Synergism indexes equal to 0.5 or 1.0, indicated synergism against the former and independent action, against the latter species.

Conclusions

In vitro, DODAB acted effectively both as micobactericidal agent and carrier for rifampicin. The novel assemblies at reduced doses may become valuable against tuberculosis.