Articles
EFFECT OF EXTRACTION METHODS ON THE COMPOSITION OF ESSENTIAL OILS
Article number
597_4
Pages
49 – 56
Language
English
Abstract
The aim of this work is to demonstrate our results on comparison of composition of essential oil fractions obtained by traditional steam distillation and supercritical fluid extraction.
The plant materials for the various extraction methods were selected from the Asteraceae and Lamiaceae families.
For the supercritical fluid extraction (SFE) carbon dioxide was used as supercritical solvent.
The extracts were collected by stage wise precipitation in two separators.
The waxy product and extract rich in essential oil were collected in the lst and in the 2nd separator respectively.
The traditional water steam distillation (SD) was carried out in the special apparatus of the Hungarian Pharmacopoea (7th ed.). GC analysis was carried out on capillary silica fused columns coated with DB-1701 and the specific chiral columns coated with Rt-
DEX m or Rt- DEX sm.
Comparing the composition of steam distilled oils with that of volatile SFE fractions the following general characteristics were established.
The SFE fractions were richer in monoterpene-esters and poorer in alcohols than the traditional essential oils (clary sage, lavander). Regarding the distribution of the monoterpene and sesquiterpene compounds, the SFE fractions contained sesquiterpene hydrocarbons in higher percentage than the distilled oils (Salvia triloba). Furthermore, the proportion of sesquiterpenes increased in SFE fractions collected successively with time (Salvia officinalis) similar to the ratio of oxygenated monoterpenes to monoterpene hydrocarbons (Rosmarinus officinalis). In other cases it was verified that part of the mono- and sesquiterpenes were present originally in bound form (glycosides) in plants.
Thus they appeared only in essential oil fractions after previous acidic treatment (Thymus, Origanum, Satureja species). During the supercritical extraction the azulenogene sesquiterpene lactones did not transform to azulenes (in chamomile, yarrow), but the non volatile SFE fraction of some Asteraceae plants contained sesquiterpene-
-lactones of unchanged structure.
The plant materials for the various extraction methods were selected from the Asteraceae and Lamiaceae families.
For the supercritical fluid extraction (SFE) carbon dioxide was used as supercritical solvent.
The extracts were collected by stage wise precipitation in two separators.
The waxy product and extract rich in essential oil were collected in the lst and in the 2nd separator respectively.
The traditional water steam distillation (SD) was carried out in the special apparatus of the Hungarian Pharmacopoea (7th ed.). GC analysis was carried out on capillary silica fused columns coated with DB-1701 and the specific chiral columns coated with Rt-
DEX m or Rt- DEX sm.Comparing the composition of steam distilled oils with that of volatile SFE fractions the following general characteristics were established.
The SFE fractions were richer in monoterpene-esters and poorer in alcohols than the traditional essential oils (clary sage, lavander). Regarding the distribution of the monoterpene and sesquiterpene compounds, the SFE fractions contained sesquiterpene hydrocarbons in higher percentage than the distilled oils (Salvia triloba). Furthermore, the proportion of sesquiterpenes increased in SFE fractions collected successively with time (Salvia officinalis) similar to the ratio of oxygenated monoterpenes to monoterpene hydrocarbons (Rosmarinus officinalis). In other cases it was verified that part of the mono- and sesquiterpenes were present originally in bound form (glycosides) in plants.
Thus they appeared only in essential oil fractions after previous acidic treatment (Thymus, Origanum, Satureja species). During the supercritical extraction the azulenogene sesquiterpene lactones did not transform to azulenes (in chamomile, yarrow), but the non volatile SFE fraction of some Asteraceae plants contained sesquiterpene-
-lactones of unchanged structure.
Authors
E. Lemberkovics, Kéry, A. Kakasy, E. Szöke, B. Simái
Keywords
essential oils, mono-, sesquiterpenes, volatile phenolic compounds, neutral and acidic steam distillation, supercritical extraction, Lamiaceae, Asteraceae
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