Extraction and Fractionation of Bioactive Compounds from Aromatic Plants

摘要

Extracts were isolated from aromatic and medicinal plants by supercritical fluid extraction with carbon dioxide (SFE-CO_2), with and without using co-solvent ethanol and Soxhlet extraction with pentane. The following plants were extracted: lemon balm (Melissa officinalis), hyssop (Hyssopus officinalis), catnip (Nepeta cataria), stinging nettle (Urtica dioica), sage (Salvia officinalis), summer savory (Satureja hortensis), gum plant flowers (Grindelia robusta) and tubers of tigernut (Cyperus esculentus). The highest yields in most cases were obtained by Soxhlet extraction, except for gum plant flowers. Medium yields were obtained by SFE-CO_2 with co-solvent, and the lowest ones (except for summer savory and lemon balm) by SFE-CO_2 using pure CO_2. The effect of ethanol on the extract yield and composition was assessed by using two separators operating at 40°C, 20 and 5 MPa, respectively (extraction was performed at 300-315 bar and 60°C). The total amount of extracted substances in the first separator was remarkably lower than in the second one. The yield in the first separator increased when the concentration of ethanol was higher. Preliminary screening of extract composition by GC/MS and HPLC/UV/MS revealed differences in the distribution of individual compounds in extracts. For instance, in case of pure CO_2 phenolic compounds were precipitated mainly in the second separator (5 MPa), while in case of added ethanol the fraction distributed more evenly between the first and the second separators.