Anti-mycobacterial Activity of 22 Iranian Endemic or Rare Plant Extracts Against Multi-drug and Extensively Drug-resistant Mycobacterium tuberculosis.

Abstract

Due to side-effects and low efficacy of common drugs on new resistant strains of Mycobacterium tuberculosis (Mtb), investigation on novel drugs and natural compounds from rich sources of endemic plants is required. Thus, in the present study, the anti-mycobacterial effects of 22 Iranian endemic or rare plant extracts on multi-drug resistance (MDR) and extensively-drug resistance (XDR) Mtb isolates were evaluated. Twenty-two Iranian endemic and rare plant species from 9 families were collected and extracted by methanol. Their inhibitory-effects were then evaluated against Mtb H37Rv strain, seven clinical MDR-TB, and two XDR-TB isolates using the resazurin microtiter assay (REMA) method. The best of them were then fractionalized by five different polar solvents (Petroleum- Ether, Dichloromethane, Ethyl-Acetate, n-butanol, and water). To find anti-mycobacterial fractions, the inhibitory effect of isolated fractions was tested on Mtb H37Rv. Out of the 22 plants, 14 plant extracts demonstrated anti-mycobacterial activity with minimum inhibitory concentration (MIC) ranging from 4 to 30μg/mL against Mtb H37Rv. Eight plant extracts also exhibited anti-mycobacterial activity against MDR and XDR clinical strains of Mtb by MICs, i.e., 15-60μg/ml. Crinitaria grimmii and Linum album were the best antimycobacterial plants. Among fractions of Crinitaria grimmii, dichloromethane and n-butanol, and for Linum album, dichloromethane and Ethyl-Acetate fractions displayed more anti-mycobacterial effect as compared to crude extract on Mtb. The present study confirms the potential role of some plants to treat respiratory diseases as our results have demonstrated that these plants exhibit anti-mycobacterial activity in the acceptable range against Mtb. Thus, these plants could be good sources and alternatives of plant metabolites for anti-TB-drug development.