Antimycobacterial activity of medicinal plants from Mozambique

Lannea stuhlmanni, Maytenus heterophylla, Maytenus senegalensis, Sarcostemma viminale and Tabernaemontana elegans are medicinal plants used in Mozambique to alleviate symptoms and treat pulmonary diseases, including tuberculosis [1].

Hereby we present results from an ethnopharmacological study conducted in order to validate the traditional use of these species against mycobacteria strains, specifically drug-sensitive and drug-resistant ones. Therefore in vitro antimycobacterial activity of nine hydroethanol extracts from different plant parts were screened through a rapid radiometric method. All extracts were tested in triplicate and the minimum inhibitory concentrations (MIC) refers to the mean arithmetic value. Five extracts have shown activity against the drug-sensitive Mycobacterium tuberculosis ATCC 700457. L. stuhlmanni root, M. senegalensis leaf, S. viminale root, and T. elegans leaf and root extracts were the most active extracts, demonstrating MIC ranged from 150–175µg/mL. T. elegans root extract was the most active. Concerning the drug-resistant strains (M. tuberculosis ATCC 35822– isoniazide resistant; M. tuberculosis ATCC 35838– rifampin resistant), T. elegans root extract, T. elegans leaf extract and M. heterophylla root extract have shown the lowest MIC values, ranging from 150–175µg/mL.

In order to localise the biological activity some active extracts were partitioned by liquid-liquid extraction. M. senegalensis ether fraction exhibited the most promising results against the drug-sensitive mycobacterium strain (MIC=150µg/mL). Prospective studies include the establishment of the chemical profile of the active extracts and fractions and identification of the active compounds. Results confirm the medicinal value of these plants.

References: [1] Jansen, P., Mendes, O. (1991) Plantas Medicinais – Seu Uso Tradicional em Moçambique. Imprensa do Partido. Maputo.