Chemical composition and antimicrobial activity of the essential oil of Ocimum basilicum L. (sweet basil) from Western Ghats of North West Karnataka, India

CONTEXT: Ocimum basilicum L. (Lamiaceae) commonly known as sweet basil, has been used as a traditional medicinal plant for the treatment of headaches, coughs, diarrhea, constipation, warts, worms, and kidney malfunctions. MATERIALS AND METHODS: The essential oil of the flowering aerial parts of O. basilicum growing in the Western Ghats region of North West Karnataka, India, was obtained by hydro-distillation and analyzed by gas chromatography equipped with flame ionization detector and gas chromatography coupled to mass spectrometry (GC–MS). The oil was tested against six Gram-positive, eight Gram-negative bacteria, and three fungi by the tube-dilution method at a concentration range of 5.00-0.009 mg/mL. RESULTS: Twenty-five constituents were identified in the essential oil of O. basilicum. The major constituents were identified as methyl eugenol (39.3%) and methyl chavicol (38.3%), accounting for 98.6% of the total oil. The oil was found to be active against Gram-positive, Gram-negative bacteria, and fungi with minimal bactericidal concentration values in the range of 0.143 ± 0.031 to 0.572 ± 0.127 mg/mL, 0.781 ± 0.382 to 1.875 ± 0.684 mg/mL, and 0.312 ± 0.171 to 0.442 ± 0.207 mg/mL, respectively. CONCLUSION: The essential oil of O. basilicum of this region contains methyl eugenol/methyl chavicol chemotype and has bactericidal properties.