Antimycobacterial potential of Trachyspermum ammi seed essential oil via fume contact and determination of major compounds

Trachyspermum ammi (L.), commonly known as carrom seeds or Ajwain, has been extensively studied for its medicinal properties. In this study, anti-mycobacterial effect of AEO in liquid and fume form was investigated against Mycobacterium smegmatis and Mycobacterium tuberculosis (M. tb). Results showed that AEO inhibits the growth of M. smegmatis at 0.03 mg/mL and becomes bactericidal at 0.125 mg/mL. MICs were observed at 0.03, 0.125 and 0.06 mg/mL against M. tb (H37Rv), isoniazid- and rifampicin-resistant (RIF-R) strains. Inverted disc-fume assay revealed AEO and Thymol efficiently inhibit the growth of M. smegmatis and M. tb. Similarly, in fume contact AEO and Thymol demonstrated antibiofilm activity at a dose of 1.25 mg/mL air and 40 mg/mL air against M.smegmatis effectively. GC-MS analysis showed that Thymol was the dominant compound. These findings suggest that the use of AEO in fume form may serve as a promising strategy as an anti-mycobacterial activity against M. tb