Coleus zeylanicus belongs to the family Lamiaceae and it is medicinally important aromatic herb. The genus Coleus contains a number of medicinally important compounds such as volatile oils, alkaloids, flavonoids, saponins and fatty acids. The present study describes the antimicrobial activity of Coleus zeylanicus against various pathogenic bacteria and fungi. The essential oil from 100g of leaves of the plant was extracted by hydro distillation using Clevenger type apparatus for 2-3 hours. The essential oil thus extracted was analyzed by GC-MS analysis for the first time. The essential oil was subjected to antibacterial tests, using disc diffusion method. In the GC-MS analysis totally sixty two components were identified of which γ-Selinene (11.77%), Geroniol (11.71%), Valencene/Eremophyllene (5.98%), m-cymene (4.59%), Ledol (4.35%), α-Bergamotene (3.61%), 10S,11S Himachala-3(12) 4-diene (3.0%), α-Cypenene (2.74%), Fencyl acetate (2.62%), α-Pinene (2.57%), Azulene (2.25%), β-Bisabolene (2.25%), 2-Camphonyl acetate (2.08%) were found to be the major phytocomponents. The oil revealed a weak to strong antibacterial activity against Pseudomonas fluorescence, Pseudomonas aeruginosa, Microcoocus luteus, Escherichia coli, Staphylococcus aureus, Salmonella typhi and Bacillus cereus. The oil was also tested for its antifungal property against two fungal strains Aspergillus niger and Candida albicans. The highest antifungal activity was found by Candida albicans.
