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Free and Bond Volatile Compounds from Candytuft, Iberis sempervirens L.

Iberis sempervirens L. belongs to Brassicaceae family. The plants of this family contain glucosinolates. The glucosinolates and their aglycones are biological active compounds. Composition of the obtained aglycones depends on the structure of the side chains in glucosinolates and degradation conditions such as pH-values, temperatures, Fe2+ ions and specific protein (Ikan, 1999.). Up to now, the chemical composition of these aglycones and O-aglycones from candytuft has not been reported. The volatiles of Iberis sempervirens were isolated by hydrodistillation and analyzed using GC and GC/MS. The volatiles were isolated from fresh plant material prior and after the autolysis (Al-Gendy et al., 2003.) and from dried plant material. Isothiocyanates, nitriles aliphatic alcohols, carbonyls, fatty acids, hydrocarbons, terpene compounds, C13-norisoprenoids and phenylpropane derivatives were identified. The major components in 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%). Other compounds were 3-methylthiopropyl isothiocyanate, phenyl isothiocyanate, benzenepropanonitrile, 1-cyano-4, 5-epithiopentane. The volatiles that were isolated after the autolysis are more complex then other two isolates. Some of them were identified in O-aglycones as eugenol, (Z)-3-hexene-1-ol, 1H-indole. Further, from the fresh plant material O-glycosides of volatile compounds were isolated and purified by selective extraction and column chromatography. After hydrolysis of O-glycosides using β -glucosidase liberated volatile O-aglycones were also analysed by GC and GC/MS. Compounds with sulfur and nitrogen (which are characteristic for glucosinolates) were not identified among these compounds. Nineteen O-aglycones were identified. The main O-aglycones were: eugenol (15.2%), 2-phenylethanol (12.9 %), 2-hydroxy-β -ionone (10.6%), 2-tert-buthyl-5-methylphenol (9.2%) and methyl-2, 5-dihidroxybenzoate (4.5%).

Iberis sempervirens; glucosinolates; o-glycosides of volatiles; aglycones; GC-MS

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