Abstract

Tuberculosis is a serious chronic infectious disease affecting large global population. While efforts to control tuberculosis have intensified, they are challenged by rapid drug resistance development. For this reason, prospecting for compounds with potential antituberculous activity have been stepped up. The current study was done in a participatory appraisal manner to identify ten plants commonly used for management of “persistent coughs”. Bioassays were conducted against Mycobacterium tuberculosis (H37Rv ATCC 27294) using the BACTEC MGIT^™ 960 system. This was followed by assay of toxicity of the extracts towards Vero cells (ATCC CCL-81). Six extracts showed remarkable antitubercular activity. Four extracts had complete inhibition (0 GU- Growth Units) of Mycobacterium tuberculosis. The extracts were tested for their general antimicrobial activity and found to be broad spectrum antimicrobials. The highest activity against Escherichia coli (15.3 mm) was by Cissampelos pareira, while Mangifera indica yielded the highest activity against Staphylococcus aureus (11.7 mm) and Candida albicans (12.0 mm). In addition, six crude methanolic extracts were found to be within the acceptable toxicity limit (CC₅₀<90 µg/ml). The observed activity is attributable to phytochemicals in the extracts, including: phenols, terpenoids, flavonoids and anthraquinones. These findings could partly explain observed “positive” treatment outcome by indigenous people using these plant formulations.

Key words: Antibacterial activity, antituberculous activity, BACTEC MGIT^™ 960 system, cytotoxicity, flavonoids, phytochemicals, terpenoids, Vero cells.