Free and bound sulphur containing and other volatile compounds from evergreen candytuft (Iberis sempervirens L.)

Volatile fractions of evergreen candytuft, Iberis sempervirens (Brassicaceae), were isolated by simultaneous hydrodistillation-extraction from fresh plant material prior and after autolysis and from dried plant material and were then analyzed using GC and GC-MS. Isothiocyanates, nitriles, aliphatic alcohols, carbonyls, fatty acids, hydrocarbons, terpene compounds, C-13-norisoprenoids and phenylpropane derivatives were identified - thirty-nine components in all. Major components of all samples were: 3-butenyl isothiocyanate (17.4-63.3%), 5-methylthiopentanonitrile (2.2-9.5%), 4-methylthiobutanonitrile (4.8-6.9%), allyl isothiocyanate (4.0-6.6%), 4-methylthiobutyl isothiocyanate (2.9-6.2%) and 3-methylthiopropyl isothiocyanate (1.3-3.4 %). Oil isolated after autolysis is more complex than the other two oils. It is composed of a large number of compounds. Some of them are identified as O-aglycones such as eugenol, (Z)-3-hexene-1-ol and 1H-indole. O-glycosides of volatile compounds were isolated from fresh plant material and purified by selective extraction and column chromatography. After hydrolysis with beta-glucosidase, the liberated volatile aglycones were also analyzed by GC and GC-MS. Nineteen aglycones were identified. The main aglycones identified were: eugenol (15.2%), 2-phenylethanol (12.9%), 2-hydroxy-beta-ionone (10.6%), 2-tert-butyl-5-methylphenol (9.2%) and methyl-2,5-dihydroxybenzoate (4.5%).