Evaluation of sixty Thai medicinal plants used for treatment of TB and TB-related symptoms for in vitro inhibitory activity against Mycobacterium tuberculosis H37Ra

A total of 60 Thai medicinal plants documented as previously used for treatments of TB and TB-related symptoms were collected. A total of 120 dichloromethane extracts of various parts of these plants were prepared and evaluated for their activities against Mycobacterium tuberculosis H37Ra strain using the Microplate Alamar Blue Assay (MABA). For each extract, the minimum inhibitory concentration (MIC) was determined. The extracts had weak to significant activity, with MICs ranging from 0.1 to 200 μg/ml. Approximately 26.7 % of the collected plants (15.8 % of all plant extracts) showed antimycobacterial activity, with significant MICs ≤ 25 μg/ml. These results supported the use of ethnomedicinal records for anti-TB drug discovery. Parts of some plants may serve as candidate sources for identifying chemical constituents that have potential of being developed into anti-TB drugs.