Antimycobacterial and antibiofilm activity of garlic essential oil using vapor phase techniques

Garlic is a well-known species of the genus Allium that acts as a natural chemotherapeutic agent and used for cure and prevention against enteric diseases. In addition, its essential oil has provided a promising way to treat different human associated diseases. Consequently, Mycobacterium tuberculosis causes tuberculosis among immunosuppressed individuals and develops resistance rapidly due to inappropriate therapy. Indeed, an alternative therapy is need of the hour to control resistance of mycobacterial strains. Concerned with the development of drug-resistant strains, garlic essential oil (GEO) in liquid and volatile phase was investigated against Mycobacterium smegmatis using in-vitro techniques. Furthermore, validation of anti-mycobacterial effect using GEO was also determined on M. tuberculosis with its drug resistant variants. Different in-vitro techniques, that is, extraction and identification of five major volatile constituents from GEO using gas chromatography-mass spectrometry, were initially analyzed and screened out for exploration of anti-mycobacterial susceptibility tests. In addition, inverted disc method and anti-biofilm assay by GEO vapor were determined for evaluating its volatile efficacy. The efficiency of GEO in liquid phase showed growth inhibiting value at 0.03 mg/mL and 0.5 mg/mL as bactericidal concentration against M. smegmatis. Whereas, M. tuberculosis (H37Rv), isoniazid, and rifampicin resistant strains were found to be inhibitory concentration at 0.003, 0.06, and 0.03 mg/mL, respectively. Furthermore, 1 mg for inverted disc-vapor assay and 0.125 mg for antibiofilm assay in air-liquid interface were found to prevent M. smegmatis growth efficiently. Thus, vapor contact of GEO serves as a novel strategy for anti-mycobacterial activity for TB-disease. In addition, it might be introducing a novel volatile therapy technique against different pulmonary infection.