Anti-mycobacterial Activity of Extracts from Plants used in Mexico for the Treatment of Infectious Diseases

Twenty seven extracts from eight medicinal plants used in Morelos, Mexico, for the treatment of several infectious diseases were screened for their in vitro anti-Mycobacterium tuberculosis (anti-MTB) activity on H37Rv strain of Mycobacterium tuberculosis (MTB), using the microplate Alamar assay test. Extracts (hexane, dichloromethane and methanol) from wild specimen of Valeriana edulis showed the most significant (p<0.05) activity against this strain (MICs values of 3.125, 25.0 and 50.0 µg/mL, respectively). On the other hand, hexanic and dichlorometanic extracts from in vitro-cultivated species of V. edulis also showed significantly activity against of M. tuberculosis (MICs values of 12.5 and 50.0 µg/mL, respectively). Most active extract (hexanic) obtained from V. edulis was also assayed against the drug-resistant strain (CIBIN 99), and the MIC value was 50 µg/mL. A qualitative TLC analysis of extracts from wild and in vitro-cultivated species of V. edulis showed that both content different chemical constituents. So, this last result explains the difference between anti-MTB activities of the extracts. Finally, dichloromethanic extracts from Lepechinia caulescens also showed a significantly activity against of M. tuberculosis (MIC 100 µg/mL). In conclusion, V. edulis and L. caulescens hexanic extracts are sources for the isolation of new or known compounds that could be used as leads for development of potential anti-MTB drugs.