The antibacterial activities of mikanolide and its derivatives.

OBJECTIVE The sesquiterpene, mikanolide, was found to possess antibacterial activity. As a result, a structure-activity relationship study was carried out on mikanolide and eleven of its derivatives. METHODS Mikanolide and two of its derivatives were isolated from organic extract of Mikania micrantha using chromatographic methods. Nine additional derivatives were synthesized and all were investigated for their antibacterial activity against the Gram positive pathogen Staphylococcus aureus and beta haemolytic Streptococcus group A (BHSA) as well as the Gram negative Escherichia coli using the disk diffusion assay. RESULTS The investigation revealed that only four of the derivatives displayed antibacterial activity and only pathogens Staphylococcus aureus and beta haemolytic Streptococcus group A were susceptible at a concentration of 100 microg per disk. However there was an increase in activity for three of the derivatives in comparison to mikanolide. CONCLUSION This study underscores the potential for phytochemicals from locally available plants to be further investigated and developed as antibacterial agents.