Chemical Composition and Antibacterial Potential of Essential Oils from Artemisia Capillaris, Artemisia Nilagirica, Citrus Limon, Cymbopogon Flexuosus, Hedychium Spicatum and Ocimum Tenuiflorum

Essential oils from Artemisia nilagirica (Clarke) Pamp., Artemisia capillaris Thunb., Cymbopogon flexuosus (Nees ex Steud.) Watson, Hedychium spicatum Sm., Citrus limon (L.) Osbeck and Ocimum tenuiflorum L. were isolated to evaluate their antibacterial activity and to assess the synergistic effect of their mixture of equivalent amounts. The components of essential oils were elucidated by gas chromatography retention indices relative to n-alkanes and mass spectrometry. Among total characterised constituents, the major ones found in A. nilagirica, A. capillaries, C. flexuosus, H. spicatum, C. limon and O. sanctum were linalool (16.29%), capillene (42.06%), α -citral (28.08%), 1,8-cineole (30.84%), limonene (49.38%) and β -ocimene (22.80%), respectively. These oils and their formulation of equivalent amounts exhibited noteworthy activities against Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeruginosa and Escherichia coli. At a concentration of 100 μg/mL, all the oils and their formulation showed IZDs of 9-30 and 29-38 mm, respectively, whereas, MICs were recorded to 6.25-50 and 3.125 μg/mL, respectively. The study concludes that essential oils and their formulation exhibited strong activity against all bacterial species. The promising activity of novel formulation as compared to ampicillin is perhaps due to synergistic effect of its constituents, and the same could become a promising source of an antibiotic agent in near future.