Science Letters

Chemical Composition and Antibacterial Activity of Essential Oil from Kenyan Conyza bonariensis (L.) Cronquist

Racheal Musembei, Kiplimo Jepkorir Joyce*

Department of Physical Sciences, School of Science, University of Kabianga, PO box 2030, Kericho-20200, Kenya

Abstract

The utilization of plants to treat sicknesses and to prevent diseases, including epidemics, has been in practice for thousands of years. The understanding of their therapeutic properties has been passed over the centuries within and among individual communities. Secondary metabolism produces active compounds which are usually responsible for the biological and pharmacological properties of some plant species used for the management of communicable diseases. Presently, the antimicrobial activity of several plants, up to now considered empirical has been scientifically established. Several studies have aimed to explain the chemical composition and the mechanisms involved in microbial growth inhibition, either separately or together with conventional antimicrobial compounds. In this study, the essential oil from aerial parts of Conyza bonariensis (L.) Cronquist collected from Kabianga division, Kericho County, Kenya was obtained by hydro-distillation and analyzed by GC-MS. The major components were monoterpene hydrocarbons; limonene (8.26%), trans-ocimene (3.74%) and sesquiterpene hydrocarbon trans-farnesene (3.17%), and among other compounds isolated an aldehyde, 1H-Indene-3-carboxaldehyde, 2,6,7,7a-tetrahydro-1,5-dimethyl yielded 49.14%. The antibacterial activity indicated that the oil was active against the bacterial strains tested. The minimum inhibitory concentration for the oil against Escherichia coli was 12.5%, while that of Salmonella typhi was 6.25%. The results suggested that the essential oil of C. bonariensis can be developed as a safe, natural and alternative method for controlling bacterial infections.