Anti-tuberculosis activity of selected medicinal plants against multi-drug resistant Mycobacterium tuberculosis...

Emergence of multi-drug resistant (MDR) and extensively-drug resistant (XDR) strains of Mycobacterium tuberculosis has further complicated the problem of tuberculosis (TB) control. Medicinal plants offer a hope for developing alternate medicines for the treatment of TB. The present study was done to evaluate in vitro anti-tubercular activity of five medicinal plants viz., Acalypha indica, Adhatoda vasica, Allium cepa, Allium sativum and Aloe vera.

Aqueous extracts of leaves of A. indica, A. vasica, bulbs of A. cepa, cloves of A. sativum and pure gel of A. vera leaves, were tested in vitro for their activity against two MDR isolates (DKU-156 and JAL-1236), reference susceptible strain M. tuberculosis H37Rv as well as rapid grower mycobacterial pathogen M. fortuitum (TMC-1529) using Lowenstein Jensen (L-J) medium and colorimetric BacT/ ALERT 3D system. Activity in L-J medium was evaluated by percentage inhibition which was calculated by mean reduction in number of colonies on extract containing as compared to extract free controls.

Extracts of all the five plants A. indica, A. vasica, A. cepa, A. sativum and A. vera exhibited anti-tuberculosis activity in L-J medium, the proportion of inhibition of these plants extract in respect mentioned above is 95, 32, 37, 72, 32 per cent, respectively for MDR isolate DKU-156 and 68, 86, 79, 72, 85 per cent, respectively for another MDR isolate JAL-1236, while for sensitive M. tuberculosis H37Rv, inhibition was found to be 68, 70, 35, 63 and 41 per cent, at 4 per cent v/v concentration in L-J medium. There was no inhibition against rapid grower M. fortuitum (TMC-1529). In BacT/ALERT also, extracts of these plants showed significant inhibition against M. tuberculosis.

Our findings showed that all these plants exhibited activity against MDR isolates of M. tuberculosis. While the anti-TB activity of A. vera, A. vasica and A. sativum against MDR isolates confirm earlier results, activity of the extracts of A. indica and A. cepa is reported for the first time. Further studies aimed at isolation and identification of active substances from the extracts which exhibited promising activities, need to be carried out.