Antibacterial activity of Ocimum gratissimum L. essential oil

The essential oil (EO) of Ocimum gratissimum inhibited Staphylococcus aureu s at a concentration of 0.75 mu g/ml. The minimal inhibitory concentrations (MICs) for Shigella flexineri, Salmonella enteritidis, Escherichia coli, Kl ebsiella sp., and Proteus mirabilis were at concentrations ranging from 3 t o 12 mu g/ml. The endpoint was not reached for Pseudomonas aeruginosa (grea ter than or equal to 24 mg/ml). The MICs of the reference drugs used in thi s study were similar to those presented in other reports. The minimum bacte ricidal concentration of EO was within a twofold dilution of the MIC for th is organism. The compound that showed antibacterial activity in th EO of O. gratissimum was identified as eugenol and structural findings were further supported by gas chromatography/mass spectra retention time data. The stru cture was supported by spectroscopic methods.