Chemical composition, antibacterial activity in vitro and brine-shrimp toxicity of the essential oil from inflorescences of Ocimum gratissimum L., Lamiaceae.

The essential oil obtained by hydrodistillation of the inflorescences of Ocimum gratissimum L. was analyzed by GC/MS. The main constituents were eugenol (81.94%) and γ-muurolene (12.58%). Antibacterial activity was shown against all assayed strains by the broth microdilution method. It's worth noting the activity against resistant strains of Enterococcus faecalis, Staphylococcus aureus and Escherichia coli. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values ranged between 0.5-2 mg/mL and 1-4 mg/mL, respectively. Preliminary toxicity assayed by the brine-shrimp (Artemia salina L.) test showed LC50 values of 233.8 (200.7 - 272.0) µg/mL and 186.1 (144.1 - 228.5) µg/mL, respectively for the essential oil and eugenol (positive control).

Ocimum gratissimum; inflorescences; essential oil; antibacterial activity