Essential Oils in the Ranunculaceae Family: Chemical Composition of Hydrodistilled Oils from Consolida regalis, Delphinium elatum, Nigella hispanica, and N. nigellastrum Seeds by Ladislav Kokoska a ) b ), Klara Urbanova c ), Pavel Kloucek d ), Lenka Nedorostova d ), Lucie Polesna a ), Jan Malik b ), Pavel Jiros c ), Jaroslav Havlik e ), Jaroslav Vadlejch b ), and Irena Valterova* c ) a ) Departmentof Crop Sciences and Agroforestry, Institute of Tropics and Subtropics, Czech University of Life Sciences Prague, Kamycka 129, CZ-165 21 Prague 6-Suchdol b )Department of Zoology and Fisheries, Faculty of Agrobiology, Food and Natural Resources, Czech University of Life Sciences Prague, Kamycka 129, CZ-165 21 Prague 6-Suchdol c ) Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo n. 2, CZ-166 10 Prague 6 (phone: þ 420 220183298; fax: þ 420 220183582; e-mail: irena@uochb.cas.cz) d )Department of Crop Production, Faculty of Agrobiology, Food and Natural Resources, Czech University of Life Sciences Prague, Kamycka 129, CZ-165 21 Prague 6-Suchdol e )Department of Microbiology, Nutrition and Dietetics, Faculty of Agrobiology, Food and Natural Resources, Czech University of Life Sciences Prague, Kamycka 129, CZ-165 21 Prague 6-Suchdol In this study, we analyzed the chemical composition of volatile oils hydrodistilled from seeds of Consolida regalis , Delphinium elatum, Nigella hispanica, and N. nigellastrum using GC and GC/MS. In C. regalis , octadecenoic (77.79%) and hexadecanoic acid (8.34%) were the main constituents. Similarly, the oils from D. elatum and N. hispanica seeds consisted chiefly of octadecadienoic (42.83 and 35.58%, resp.), hexadecanoic (23.87 and 28.59%, resp.), and octadecenoic acid (21.67 and 19.76%, resp.). Contrastingly, the monoterpene hydrocarbons a-pinene ( 34.67%) and b-pinene ( 36.42%) were the main components of N. nigellastrum essential oil. Our results confirm the presence of essential oils in the family Ranunculaceae and suggest chemotaxonomical relationships within the representatives of the genera Consolida, Delphinium, and Nigella. In addition, the presence of various bioactive constituents such as linoleic acid, ()-b-pinene, squalene, or carotol in seeds of D. elatum, N. hispanica, and N. nigellastrum indicates a possible industrial use of these plants. Introduction. – The Ranunculaceae (buttercup or crowfoot family) is a family of flowering plants that consists of 50 to 60 genera and ca. 2,500 species of annual to perennial herbs, (sub)shrubs, or woody climbers distributed worldwide, but most commonly in the temperate and cold areas of the northern hemisphere. Many genera such as Aconitum, Delphinium, Helleborus , or Trollius are well-known as cultivated ornamentals, a number of them being highly poisonous [1]. Some species (e.g. , Cimicifuga racemosa, Hydrastis canadensis , Nigella sativa) are used as herbal medicines or spices [2] [3]. From a chemotaxonomical point of view, the species belonging to the buttercup family contain mainly isoquinoline and diterpenoid alkaloids together with glycosides of various triterpenes and steroids (e.g. , triterpenoid saponins, cardenolides, or bufadienolides). The lactone protoanemonin is also very common in some genera [2][4]. CHEMISTRY & BIODIVERSITY – Vol. 9 (2012) 151  2012 Verlag Helvetica Chimica Acta AG, Zürich