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Diplotaxis tenuifolia (L.) DC: MICROWAVE EXTRACTION vs. HYDRODISTILLATION

The genus Diplotaxis contains around 34 different plant species and represents one of the flowering genera of the Brassicaceae family. Glucosinalates (GLs), naturally occurring compounds in this family, with isothiocyanates (ITCs) and nitriles as their typical degradation products, make them interesting for the research. ITCs and nitriles can be formed enzymatically, chemically and/or thermally. The goal of the present study was the isolation of the volatiles from wild-growing Diplotaxis tenuifolia (L.) DC. (Split). Two different approaches of isolation of volatiles from fresh plant material include thermal degradation of GLs at 100 °C in both cases: a) conventional hydrodistillation using a Clevenger type apparatus for 2.5 hours ; b) microwave-assisted extraction (MAE) using power of 500W for 35 min. MAE isolation represents new “green” technique without adding any solvents and two fractions were obtained i.e. the fragrance (by distillation) and flavour extraction (by gravity). The resulting volatiles analysed by GC-MS indicated that the main GL was 4-(methylsulfanyl)butyl GL (glucoerucin) which degraded differently i.e. 4-(methylsulfanyl)butyl ITC was dominant degradation product obtained by hydrodistillation, while 5-(methylsulfanyl)pentanenitrile was dominant degradation product obtained by MAE. Flavour fraction had greater yield (0.014%) in comparison to fragrance fraction (0.001%) as well as to hydrodistillation (0.003%).

microwave extraction, hydrodistillation, Diplotaxis tenuifolia (L.) DC, glucosinolates

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