Chemical constituents and antimicrobial and antioxidant potentials of essential oil and acetone extract of Nigella sativa seeds

The antifungal, antibacterial and antioxidant potentials of essential oil and acetone extract of black cumin were investigated by different techniques. In the inverted petriplate method, the essential oil showed complete zones of inhibition against Penicillium citrinum at a 6 mu l dose. Essential oil showed complete growth inhibition against Bacillus cereus, Bacillus subtilis and Staphylococcus aureus, Pseudomonas aeruginosa at 2000 and 3000 ppm, respectively, by the agar well diffusion method. The antioxidant activity was evaluated by measuring peroxide, TBA and total carbonyl values of rapeseed oil at fixed time intervals. Both the extract and essential oil showed strong antioxidant activity in comparison with butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT). In addition, their inhibitory action in the linoleic acid system was studied by monitoring the accumulation of peroxide concentration. Their radical scavenging capacity was carried out on 2,2'-diphenyl-1-picrylhydrazyl (DPPH) radical and they showed excellent scavenging activity in comparison with synthetic antioxidants. Their reducing power was also determined, demonstrating strong antioxidant capacity of both the essential oil and extract. Gas chromatographic and gas chromatographic-mass spectrometric studies on the essential oil resulted in the identification of 38 components representing 84.65% of the total amount. The major component was p-cymene (36.2%) followed by thymoquinone (11.27%), alpha-thujene (10.03%), longifolene (6.32%), beta-pinene (3.781/6), alpha-pinene (3.33%) and carvacrol (2.12%), whereas extract showed the presence of 16 components representing 97.9% of the total amount. The major components were linoleic acid (53.6%), thymoquinone (11.8%), palmitic acid (10%), p-cymene (8.6%), longifolene (S.8%) and carvacrol (3.7%). (c) 2005 Society of Chemical Industry.