title: Comparison of chemical composition and antibacterial activity of Nigella sativa seed essential oils obtained by different extraction methods.
abstract: Nigella sativa L. seed essential oils obtained by hydrodistillation (HD), dry steam distillation (SD), steam distillation of crude oils obtained by solvent extraction (SE-SD), and supercritical fluid extraction (SFE-SD) were tested for their antibacterial activities, using the broth microdilution method and subsequently analyzed by gas chromatography and gas chromatography-mass spectrometry. The results showed that the essential oils tested differed markedly in their chemical compositions and antimicrobial activities. The oils obtained by HD and SD were dominated by p-cymene, whereas the major constituent identified in both volatile fractions obtained by SD of extracted oils was thymoquinone (ranging between 0.36 and 0.38 g/ml, whereas in oils obtained by HD and SD, it constituted only 0.03 and 0.05 g/ml, respectively). Both oils distilled directly from seeds showed lower antimicrobial activity (MICs > or = 256 and 32 microg/ml for HD and SD, respectively) than those obtained by SE-SD and SFE-SD (MICs > or = 4 microg/ml). All oil samples were significantly more active against gram-positive than against gram-negative bacteria. Thymoquinone exhibited potent growth-inhibiting activity against gram-positive bacteria, with MICs ranging from 8 to 64 microg/ml.
authors.affiliation: Department of Crop Sciences and Agroforestry, Institute of Tropics and Subtropics, Czech University of Life Sciences Prague, Kamycka 129, 165 21 Prague 6-Suchdol, Czech Republic. kokoska@its.czu.cz
authors.forename: L
authors.initials: L
authors.lastname: Kokoska
authors.forename: J
authors.initials: J
authors.lastname: Havlik
authors.forename: I
authors.initials: I
authors.lastname: Valterova
authors.forename: H
authors.initials: H
authors.lastname: Sovova
authors.forename: M
authors.initials: M
authors.lastname: Sajfrtova
authors.forename: I
authors.initials: I
authors.lastname: Jankovska
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000494:pharmacology; D001419:Bacteria / Q000187:drug effects* / Q000254:growth & development; D002849:Chromatography, Gas; D015169:Colony Count, Microbial; D019652:Extraction and Processing Industry / Q000379:methods*; D008401:Gas Chromatography-Mass Spectrometry; D008826:Microbial Sensitivity Tests; D031881:Nigella sativa / Q000737:chemistry*; D009822:Oils, Volatile / Q000737:chemistry / Q000494:pharmacology; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology; D012639:Seeds / Q000737:chemistry
chemical_list: D000900:Anti-Bacterial Agents; D009822:Oils, Volatile; D010936:Plant Extracts