Anti-Mycobacterial Potential of Tecoma Stans L. Syn. Bignonia Stans (Bignoniaceae)

In the present study antibacterial activity of aqueous and alcoholic extracts of stem bark and leaves of Tecoma stans L. syn. Bignonia stans (Bignoniaceae) was tested against MDR isolates DKU-156 and JAL-1236 of M. tuberculosis, reference susceptible strain M. tuberculosis H37Rv as well as fast growing mycobacterial pathogen M. fortuitum (TMC-1529). The leaves and bark collected between spring and summer season were dried and extracts was prepared using three portions of the dried powdered bark and leaves. It was soaked separately in 500 ml of distilled water and ethanol (98%) for 72 h and refluxed and filtrates were concentrated under vacuum at 40°C to obtain the dry extracts. Reference drug susceptible strain M. tuberculosis H37Rv as control, multi-drug resistant isolates DKU-156, JAL-1236 and fast growing mycobacterial pathogen M. fortuitum (TMC-1529) were used during the present investigation. Antimicrobial assays were performed in Lowenstein Jensen (L-J) medium and Middlebrook 7H9 broth in BacT/ALERT 3D system (Sigma-Aldrich, St. Louis, USA). The aqueous and alcoholic extracts of stem bark and leaves were incorporated in the media. Susceptibility testing of MDR isolates was also performed against streptomycin in the same batch of media for comparison of cfu on drug free controls. The results of the present investigation clearly showed that the aqueous extracts of stem bark were more effective as compared to aqueous and leaf extracts and alcoholic stem bark and leaf extracts.