In vitro inhibition of drug-resistant and drug-sensitive strains of Mycobacterium tuberculosis by Helichrysum caespititium

Antimycobacterial activity of acetone and water extracts of Helichrysum caespititium against a drug-sensitive strain of Mycobacterium tuberculosis was evaluated by the agar plate method. The acetone extract exhibited inhibitory activity at a concentration of 0.5mg ml(-1) against this strain whereas the organism was found to be partially susceptible to the water extract at 5.0mg ml(-1). The inhibitory activity of the acetone extract was confirmed using the rapid radiometric method and the minimum inhibitory concentration (MIC) was found to be 0.1mg ml(-1). Caespitate, a novel phloroglucinol, which was previously isolated and identified, from H. caespititium was also evaluated for its activity against drug-sensitive and drug-resistant strains of M. tuberculosis. The MIC of caespitate was found to be 0.1 mg/ml for all the M. tuberculosis strains. The ability of caespitate to inhibit the growth of all the strains of M. tuberculosis, shows the broad spectrum antimycobacterial activity of the compound.