Antimicrobial Activity of Solanum torvum Crude Extracts against Important Mycobacterial Strains

Tuberculosis (TB) caused by Mycobacterium tuberculosis (M. tb) complex remains a leading cause of morbidity and mortality worldwide. The zoonotic infectious condition represents a never-ending challenge for which drug discovery efforts are needed. The current study was designed to evaluate the in vitro antimycobacterial activity and phytochemical composition of hydroethanolic extracts from roots, stem bark, leaves, and unripe fruits derived from Solanum torvum, a shrub traditionally used against respiratory tract illnesses, including TB.

The phenotypic colorimetric microplate alamar blue assay was used to study the antimycobacterial activity of the hydroethanolic 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.

The roots, stem bark, leaves, and unripe fruits exhibited MIC values of 0.0195 mg/mL, 0.0781 mg/mL, 1.250 mg/mL, and 0.625 mg/mL against the pathogenic mycobacterial strain, M. tb H37Rv (ATCC 27294), respectively.

S. torvum stem bark has demonstrated significant activity against the pathogenic M. tb strain. This observation validates the ethno-pharmacological use of the plant species 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.