Supercritical CO2extraction of oleoresin from marigold (Tagetes erecta L.) flowers and determination of its antioxidant components with online HPLC-ABTS(·+) assay.

BACKGROUND: Marigold is a traditional medicine herb which shows good pharmacological activity in many aspects. It is very important to obtain and investigate the specific bioactive compounds from marigold. The objective of the study was to extract the oleoresin from marigold with supercritical CO(2) (SC-CO(2) ) at different pressures and temperatures, detect the fatty acid composition by gas chromatography-mass spectrometry and investigate the antioxidative components in the extracts by combined online high-performance liquid chromatography-2,2-azinobis-(3-ethylbenzothiazolin-6-sulfonic acid (HPLC-ABTS(•+) ) post-column assay and HPLC-tandem mass spectrometry. RESULTS: For the pressure range (20-40 MPa) and temperature range (30-70 °C), 30 MPa/70 °C gave the highest yield of oleoresin (58.9 g kg(-1) ). The dominant fatty acids of marigold flower oleoresin were linoleic acid (>26.41%), palmitic acid (>24.22%) and oleinic acid (>20.12%). Significant effects of the extraction pressure and temperature on the antioxidant activity were observed (P < 0.05). Lutein esters, α-tocopherol, ß-tocopherol, γ-tocopherol and δ-tocopherol were the dominant antioxidant compounds in the extracts. CONCLUSION: The study has shown that the yield and total antioxidant activity of the marigold extracts were affected by the pressure and temperature of SC-CO(2) , and that online HPLC technique could be used as an efficient and rapid method for separation and identification of bioactive compounds from a complex mixture.

Influence of benzylamine on the resolution of ibuprofen with (+)-(R)-phenylethylamine via supercritical fluid extraction.

The resolution of racemic ibuprofen was studied by partial diastereomer salt formation. The resolution was performed via two methods: resolution with (+)-(R)-phenylethylamine as chiral agent and resolution with a mixture of (+)-(R)-phenylethylamine and benzylamine. The diastereomers and unreacted enantiomers were separated by supercritical fluid extraction with carbon dioxide at 15 MPa and 33 degrees C. The influence of the achiral benzylamine on the resolution efficiency was studied by varying the concentrations of the structurally related amines in their mixtures, keeping the sum molar ratio of the amines to racemic ibuprofen constant at 0.55 +/- 0.02. The presence of benzylamine positively influenced the resolution efficiency at certain concentrations. The crystal structure of the salts of (+)-(R)-phenylethylamine with (-)-(R)-ibuprofen and (+)-(S)-ibuprofen, respectively, as well as the cocrystal of the benzylamine-ibuprofen salt with neutral ibuprofen molecules are presented. These structures were determined by single crystal X-ray diffraction, proving the significantly different stoichiometry of the related amines with the chiral acid, in accordance with mass balance calculations.

[Gas chromatography for analysis of essential oils. Characteristics of essential oil of Dracocephalum species and the influence of extraction method on its composition]. / Gáizkromatográfia alkalmazása illóolajok analízisére Dracocephalum fajok illóolaj jellemzoi és az extrakciós mód illóolajösszetételt befolyásoló hatása.

In this work the essential oil composition of some less known Dracocephalum species was studied and compared the effectiveness, selectivity and influence of different extraction methods (hydrodistillation, Soxhlet extraction with organic solvents and supercritical fluid extraction) on essential oils. For investigations in Hungary and Transylvania cultivated plant material was used. The analysis of essential oils was carried out by GC and GC-MS methods. The components were identified by standard addition, retention factors and mass spectra. The percentile evaluation of each volatile constituents was made on basis of GC-FID chromatograms. The accuracy of measurements was characterized by relative standard deviation. In the essential oil of D. renati Emb. (studied firstly by us) 18.3% of limonene was measured and carvone, citrals and linalyl acetate monoterpenes, methyl chavicol and some sesquiterpene (e.g. bicyclovetivenol) determined in lower quantities. We established that more than 50% of essential oil of D. grandiflorum L. was formed by sesquiterpenes (beta-caryophyllene and- oxide, beta-bourbonene, beta-cubebene, aromadendrene) and the essential oil of D. ruyschiana L. contained pinocamphone isomers in more than 60%. The oxygenated acyclic monoterpenes, the characteristic constituents of Moldavian dragonhead were present in some tenth percent only in D. renati oil. We found significant differences in the composition of the SFE extract and traditional essential oil of D. moldavica L. The supercritical fractions collected at the beginning of the extraction process were richer in valuable ester component (geranyl acetate) than the essential oil obtained by hydrodistillation. The fractions collected at the end of supercritical were poor in oxygenated monoterpenes but rich in minor compounds of traditional oil, e.g. palmitic acid.

Application of mixtures of tartaric acid derivatives in resolution via supercritical fluid extraction.

Racemic N-methylamphetamine (rac-MA) was resolved with 2R,3R-tartaric acid (TA) and its derivatives (O,O'-dibenzoyl-(2R,3R)-tartaric acid monohydrate (DBTA) and O,O'-di-p-toluoyl-(2R,3R)-tartaric acid (DPTTA)), individually and using them in different combinations. After partial diastereomeric salt formation, the free enantiomers were extracted by supercritical fluid extraction using carbon dioxide as solvent. DBTA and DPTTA are efficient resolving agents for rac-MA, the best chiral separation being obtained at a molar ratio of 0.25 resolving agent to racemic compound for both resolving agents (ee(E) = 82.5% and ee(E) = 57.9%, respectively). Compared with the two other acids, TA is practically unsuitable for enantiomer separation (ee(E) < 5%). Applying a mixture of one individually active and one ineffective acid in half the equivalent molar ratio, when the acids are in 1:1 ratio in the mixture, the resolution efficiency values obtained exceeded those obtained by using the components individually. Decreasing the molar ratio of resolving agent mixture to 0.25, at which the individual resolving agents give the best chiral separation, the obtained resolution efficiency values did not differ significantly from those expected. The outcome of the resolution process depended only on the amount of the individually active resolving agents in the mixture.

[Influence of extraction methods on the composition of essential oils]. / Extrakciós módszerek hatása az illóolajok osszetételére.

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 Lamiaceae, Apiaceae and Asteraceae 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 1st 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-beta DEX m or Rt-beta 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, moldavian dragonhead). Regarding the distribution of the monoterpene and sesquiterpene compounds, the SFE fractions contained sesquiterpenes in higher percentage than the distilled oils (Salvia fruticosa). 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). The phtalides of lovage (Satureja hortensis) did not show regular change during the supercritical extraction. 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 super-critical extraction the azulenogene sesquiterpene lactones did not transform to azulenes (chamomile, yarrow), but SFE fractions of some Asteraceae plants contained sesquiterpene-gamma-lactones of unchanged structure.

Enantioseparation of chiral alcohols by complex formation and subsequent supercritical fluid extraction.

The very first application of supercritical fluid extraction (SFE) on enantioseparation of alcohols is discussed. Resolution of three chiral alcohols (trans-2-chloro-cyclohexanol, trans-2-bromo-cyclohexanol, and trans-2-iodo-cyclohexanol) were performed by partial complexation with (-)-O,O'-dibenzoyl-(2R,3R)-tartaric acid monohydrate (DBTA). DBTA formed diastereomeric complexes with all S,S-enantiomers stable enough to extract the unreacted alcohols with supercritical carbon dioxide. Resolution efficiency increased with the size of halogen substituents, and by the proper selection of molar ratio, pure (-)-R,R-trans-2-iodo-cyclohexanol (ee > 99%, yield: 39%) or (+)-S,S-trans-2-iodo-cyclohexanol (ee = 98%, yield: 8%) were prepared in one process step. Achieved resolution efficiency values were much higher in all resolution procedures than in any other known enantioseparation of these racemic compounds. The developed method offers an environmentally friendly, efficient alternative of currently applied resolution processes, also on a preparative scale.

Supercritical Fluid Extraction, a Novel Method for Production of Enantiomers.

Extraction of 25 different binary mixtures of racemic acids [2-(4-isobutylphenyl)propionic acid, cis- and trans-chrysanthemic, and -permetric acid] and various chiral bases with supercritical carbon dioxide permitted the conclusion that molecular chiral differentiation in a supercritical fluid is more efficient than in conventional solvents. In the majority of cases, however, complete separation could not be achieved. In five cases, remarkable partial resolutions were realized (30-75% ee) and resolution was possible on a preparative scale. The pair cis-chrysanthemic acid and (S)-(+)-2-(benzylamino)-1-butanol was studied in detail. Pressure, temperature, time, as well as the molar ratio of base and acid had a marked influence on the quantity and quality of the products. Increasing pressure or decreasing temperature resulted in higher ee values. (-)-cis-Chrysanthemic acid in 99% ee was obtained from the raffinate in a single extraction step. Multiple extractions produced the (+)-cis-acid in 90% ee.