Chemical Composition and Antimicrobial Activity of the Essential Oil of Ocimum obovatum E. Mey. Ex Benth. (Lamiaceae)

In this study, the chemical composition and antimicrobial activity of the essential oils from the leaves of Ocimum obovatum were investigated. Hydrodistillation yielded 43 compounds representing 99.5 % of the oil. The composition of the oil was analyzed using gas chromatography and mass spectrometry (GC-MS). The main compounds detected were phytol (21.46 %); 2-isopropyl-5-methyl-9-methylene-bicyclo[4.4.0]dec-1-ene (8.2 %); n-hexadecanoic acid (7.4 %); 6,10,14-trimethyl 2-pentadecanone (5.2 %); 2-ethylhexyl undecy l ester phthalic acid (5.2 %); dibutyl phthalate (4.5 %); 2,6-lutidine-N-oxide(3.4 %) and 2-(1,1-dimethylethyl)-1,4-dimethoxy-benzene (3.1 %). The essential oil was further tested in vitro against the bacteria Escherichia coli, Staphylococcus aureus, Klebsiella spp, Pseudomonas spp and Proteus spp. by disc diffusion method. The minimum inhibitory concentration against the bacteria was also determined. The oil sample was active against both gram positive and gram negative bacteria. Standard antibiotic discs with Chloramphenicol were used as positive controls.