Antimycobacterial activity of methanolic plant extract of Artemisia capillaris containing ursolic acid and hydroquinone against Mycobacterium tuberculosis.

OBJECTIVE

In order to protect against Mycobacterium tuberculosis (MTB) infection, novel drugs and new targets should be screened from the vast source of plants. We investigated the potentiality of the herbal plant of Artemisia capillaris extract (AC) against Mycobacterium tuberculosis.

DESIGN

In this study, we isolated ursolic acid and hydroquinone by bio-activity guided fractionation from the methanol extracts of AC, and tested the inhibitory effects against several strains of MTB. Anti-mycobacterial evaluation of these compounds was carried out using the MGIT™ 960 and resazurin assay. Mycobacterial morphological changes due to the treatment of these compounds were further evaluated by Transmission electron microscopy (TEM).

RESULTS

Ursolic acid (UA) and hydroquinone (HQ) inhibited the growth of both susceptible and resistant strains of M. tuberculosis. The MIC (minimum inhibitory concentration) values of both UA and HQ were 12.5 μg/ml against the susceptible strains of M. tuberculosis. Also both UA and HQ showed 12.5-25 μg/ml of MIC values against MDR/XDR MTB strains. However, against clinical strains of MTB, UA was found sensitive against those strains that are sensitive against both INH and RFP but resistant against those strains that are resistant to INH. On the other hand HQ was sensitive against all clinical strains. TEM image-analysis of the strain H37Ra after treatment with UA revealed cell wall lysis, whereas HQ-treated cells showed deformed cytoplasmic morphology.

CONCLUSION

All these results indicate that AC extracts containing UA and HQ possess promising chemotherapeutic potency against MTB for future use.