Chemical composition and antibacterial activity against Escherichia coli of extracts of a common household plant

Abstract

Plants have long been a source for a wide variety of compounds with medicinal properties; of significant interest are plant antimicrobial compounds. Given the continual increase in bacterial resistance, it is imperative that new antimicrobial compounds need to be discovered. The purpose of this study was to screen some common household plants for antibacterial activity, specifically against Escherichia coli. Leaves of 16 different household plants were subjected to methanol-water extraction and the dried extract was analyzed for antibacterial activity using the standard Kirby-Bauer disk diffusion technique. Of all the plants tested, only the Zebra plant (Aphelandra squarrosa) showed a strong antibacterial activity against E. coli. This Zebra plant extract was further analyzed by gas chromatography/mass spectrometry (GC/MS). A variety of known antibacterial compounds including glycerine 46%, phytol 10%, palmitic acid 9%, hydroquinone 6%, linoleic acid 6%, catechol 4% and decanoic acid 3% were shown to be present in the Zebra plant extract along with other compounds whose structure could not be identified at this time. This provides additional avenues for future research especially in the identification of these unknown compounds present in this plant extract which may contribute to its antibacterial activity. Key words: Chemical composition, antibacterial activity, Aphelandra squarrosa extracts, Escherichia coli.