ANTIMICROBIAL ACTION OF ESSENTIAL OILS - THE EFFECT OF DIMETHYLSULFOXIDE ON THE ACTIVITY OF CINNAMON OIL

Fifty-one essential oils extracted from plants of known origin were te sted for their antimicrobial activity against three bacteria, Pseudomo nas aeruginosa, Staphylococcus aureus, Escherichia coli and four yeast s, Torulopsis utilis, Schizosaccharomyces pombe, Candida albicans and Saccharomyces cerevisiae using the drop diffusion method. All showed a ntimicrobial activity against at least one of the micro-organisms. Fol lowing this preliminary screening, 13 essential oils showing antimicro bial activity against at least five of the micro-organisms were tested in the range 50 mu g ml(-1) to 500 mu g ml(-1) using broth micro dilu tion techniques with dimethqilsulphoxide (DMSO) as a dispersing solven t. The concentration of most of the oils required for total inhibition of growth was > 500 mu g ml(-1). Further studies on the antimicrobial action of cinnamon oil in the range 10-150 mu g ml(-1) showed that 50 -fold higher activity was found when no dispersing solvent was used.