IN VITRO BIOACTIVITY OF VENDA MEDICINAL PLANTS USED IN THE TREATMENT OF RESPIRATORY CONDITIONS

Abstract

Infectious diseases, especially those affecting the respiratory tract, represent a critical problem to health. Crude methanol and water extracts of ten Venda plants reported to be used ethnomedically in the treatment of respiratory conditions were assessed for their antimicrobial activity against standard strains and clinical isolates of Candida albicans, Haemophilis influenza, Klebsiella pneumoniae, Staphylococcus aureus, Streptococcus pneumoniae and Mycobacterium smegmatis using the disc diffusion assay. Four of the ten plants tested demonstrated antimicrobial activity. No extracts showed activity against K. pneumoniae. Minimum inhibitory concentrations (MIC), as determined by the broth microdilution assay, showed three plants, Securidaca longepedunculata, Syzygium cordatum and Tabernaemontana elegans, to possess MICs ≤ 1mg/mL. These extracts, however showed toxicity in vitro to lymphocytes. The crude extracts were tested for antioxidant activity using the TEAC assay, but only S. cordatum showed significant antioxidant activity. Phytochemical screening, performed by thin layer chromatography (TLC) using a variety of mobile phases and selective visualization reagents demonstrated various classes of compounds in the active extracts. While three plant species were identified with significant antimicrobial activity, there remains a need for identification of the bioactive constituents, as well as a further investigation of their toxicity. Acknowledgements: NRF provided funding