Antimycobacterial Efficacy of Hydroethanolic Leaf Extracts from Selected Medicinal Plants Traditionally used Against Mycobacterium tuberculosis

Abstract BACKGROUND: Mycobacterium tuberculosis ( M . tb ) is the leading cause of mortality worldwide due to a single bacterial pathogen. Antimicrobial resistance increases the likelihood of worsened outcomes in tuberculosis (TB) patients, including treatment failure and death. Multidrug-resistant strains, resistant to first-line drugs isoniazid and rifampin, and extensively drug-resistant strains with further resistance to second-line drugs, threaten control programs designed to lower TB incidence and end the disease as a public health challenge by 2030, in accordance with UN Sustainable Development Goals. The zoonotic infectious condition represents a never-ending challenge toward which drug discovery efforts are needed. The current study was designed to evaluate the in vitro antimycobacterial activity and phytochemical composition of hydroethanolic leaf extracts from Cymbopogon giganteus , Cyperus articulatus , Dissotis rotundifolia , and Phyllanthus fraternus . The medicinal plants are traditionally used against respiratory tract illnesses, including TB. METHODS: The phenotypic colorimetric microplate alamar blue assay was used to study the antimycobacterial activity of the ethanolic extracts against six mycobacterial strains. Each experiment was run in triplicate. Data generated were analyzed using descriptive statistics to obtain mean minimum inhibitory concentration (MIC) values. RESULTS: The hydroethanolic extracts from the leaves of C . giganteus , C . articulatus , D . rotundifolia , and P . fraternus exhibited MIC values of 19.5 μg/mL, 156.3 μg/mL, 156.3 μg/mL, and 78.1 μg/mL against the pathogenic mycobacterial strain, M . tb H37Rv (ATCC 27294), respectively. CONCLUSIONS: The tested hydroethanolic extracts from the leaves of C . giganteus and P . fraternus have demonstrated significant activity against the pathogenic M . tb strain. This observation validates the ethno-pharmacological use of both medicinal plants in traditional medicinal practices against TB. Further studies are required to isolate, elucidate the structure, and characterize the antimycobacterial compounds responsible for the observed activity. These will potentially contribute toward bioprospecting for a new class of ligands with activity against sensitive and drug-resistant strains of M . tb .