Indian medicinal plants as a source of antimycobacterial agents

It is estimated that one-third of the world's population is infected with tubercle bacillus and the problem of tuberculosis (TB) has been intensified due to HIV pandemic providing a large reservoir of highly susceptible individuals. Since no anti-TB drugs have been introduced in past 30 years, there is an urgent need to search for and develop new, effective and affordable anti-TB drugs. In this scenario, the plant kingdom with enormous chemical diversity may be looked as an important source of new anti-TB agents. Of 17,500 higher plant species occurring in India only about 365 species have been evaluated so far for antimycobacterial activity. The present review article describes the 255 (70% of 365) plant species from a wide range of families that have shown antimycobacterial activity. The species are enumerated in table format describing plant species and family, plant part used, type of extract and in vitro activity (MIC value), information on active compounds, if any, and uses in the ethnomedicine and Ayurveda. Interestingly, most of the plant species have shown strong positive ethnopharmacological correlation with the traditional knowledge. In addition, the recent in vitro screening methods for antimycobacterial activity are also described in brief. An attempt has been made to highlight the promising plant species for further investigation as leads for drug development.