Dorota Wianowska

Application of PLE for the determination of essential oil components from Thymus vulgaris L.

Essential plants, due to their long presence in human history, their status in culinary arts, their use in medicine and perfume manufacture, belong to frequently examined stock materials in scientific and industrial laboratories. Because of a large number of freshly cut, dried or frozen plant samples requiring the determination of essential oil amount and composition, a fast, safe, simple, efficient and highly automatic sample preparation method is needed. Five sample preparation methods (steam distillation, extraction in the Soxhlet apparatus, supercritical fluid extraction, solid phase microextraction and pressurized liquid extraction) used for the isolation of aroma-active components from Thymus vulgaris L. are compared in the paper. The methods are mainly discussed with regard to the recovery of components which typically exist in essential oil isolated by steam distillation. According to the obtained data, PLE is the most efficient sample preparation method in determining the essential oil from the thyme herb. Although co-extraction of non-volatile ingredients is the main drawback of this method, it is characterized by the highest yield of essential oil components and the shortest extraction time required. Moreover, the relative peak amounts of essential components revealed by PLE are comparable with those obtained by steam distillation, which is recognized as standard sample preparation method for the analysis of essential oils in aromatic plants.

Optimization of ASE Conditions for the HPLC Determination of Rutin and Isoquercitrin in Sambucus nigra L

Abstract The accelerated solvent extraction (ASE) procedure has been examined as a sample preparation method for the HPLC analysis of rutin and isoquercitrin in Sambucus nigra L. The experimental extraction parameters (solvent composition, temperature, operation pressure, and static extraction time) have been optimized in order to receive the best recovery of both analytes from the flowers, leaves, and berries of black elder. The ASE recoveries obtained under the optimal extraction conditions were compared with analogous ones obtained by means of the maceration technique.

Matrix solid-phase dispersion with sand in chromatographic analysis of essential oils in herbs.

INTRODUCTION Matrix solid-phase dispersion (MSPD) is a very simple, cheap and relatively quick sample preparation procedure which involves simultaneous disruption and extraction of various solid and semi-solid samples due to the direct mechanical blending of the sample with a SPE sorbent, mainly C(18). Little is known about MSPD application as a sample preparation method for the analysis of essential oil components in herbs. OBJECTIVE To evaluate if C(18) sorbent, commonly used in MSPD process, can be substituted with sand in the procedure of essential oil analysis. METHODOLOGY Essential oil extracts were obtained from mint, sage, chamomile, marjoram, savory and oregano using MSPD with C(18) sorbent or sand, pressurised liquid extraction and steam distillation. Their qualitative and quantitative compositions ware established by GC-MS and GC-FID. RESULTS The results prove that C(18) sorbent can be substituted with sand in the procedure of essential oil analysis in herbs. The recoveries of essential oil components estimated using MSPD/sand are almost equal to those using pressurised liquid extraction. CONCLUSION The results presented in the paper reveal that MSPD with sand is suitable for the isolation of essential oil components from herbs. Its extraction efficiency is equivalent to pressurised liquid extraction, recognised as one of the most efficient extraction methods. The cost of MSPD procedure for essential oil analysis can be significantly diminished by substituting C(18) with sand.

Static and dynamic superheated water extraction of essential oil components from Thymus vulgaris L.

Superheated water extraction (SWE) performed in both static and dynamic condition (S-SWE and D-SWE, respectively) was applied for the extraction of essential oil from Thymus vulgaris L. The influence of extraction pressure, temperature, time, and flow rate on the total yield of essential oil and the influence of extraction temperature on the extraction of some chosen components are discussed in the paper. The SWE extracts are related to PLE extracts with n-hexane and essential oil obtained by steam distillation. The superheated water extraction in dynamic condition seems to be a feasible option for the extraction of essential oil components from T. vulgaris L.

The influence of heavy metal stress on the level of some flavonols in the primary leaves of Phaseolus coccineus

Qualitative and quantitative analysis of flavonols was carried out in young and older primary leaves of runner bean plants (Phaseolus coccineus L.) treated with Cd2+ (25 µM) and Cu2+ excess (25 and 300 µM) for 12 days. The presence of quercetin-3-O-D-rhamnoside, kaempferol-3-O-D-rhamnoside, quercetin-3-O-D-glucuronide and kaempferol-3-O-D-glucuronide was found in the plant. Quercetin-3-O-D-rhamnoside predominated in the control and heavy metal-stressed plants. The content of individual flavonols increased under heavy metal treatment, particularly in young plants. The flavonol level depended on the metal and its concentration. A protective role of flavonols in plants under heavy metal stress is discussed.

Simplified procedure of silymarin extraction from Silybum marianum L. Gaertner.

Silymarin, a mixture of flavonolignans exhibiting many pharmacological activities, is obtained from the fruits of milk thistle (Silybum marianum L. Gaertner). Due to the high lipid content in thistle fruits, the European Pharmacopoeia recommends a two-step process of its extraction. First, the fruits are defatted for 6 h, using n-hexane; second, silymarin is extracted with methanol for 5 more hours. The presented data show that this extremely long traditional Soxhlet extraction process can be shortened to a few minutes using pressurized liquid extraction (PLE). PLE also allows to eliminate the defatting stage required in the traditional procedure, thus simplifying the silymarin extraction procedure and preventing silymarin loss caused by defatting. The PLE recoveries obtained under the optimized extraction conditions are clearly better than the ones obtained by the Pharmacopoeia-recommended Soxhlet extraction procedure. The PLE yields of silychristin, silydianin, silybin A, silybin B, isosilybin A and isosilybin B in acetone are 3.3, 6.9, 3.3, 5.1, 2.6 and 1.5 mg/g of the non-defatted fruits, respectively. The 5-h Soxhlet extraction with methanol on defatted fruits gives only ∼72% of the silymarin amount obtained in 10 min PLE at 125°C.

Extraction Methods of 10-Deacetylbaccatin III, Paclitaxel, and Cephalomannine from Taxus baccata L. Twigs: A Comparison

Abstract Four types of solvent extraction methods (ultrasound and microwave assisted extraction, pressurized liquid extraction, and extraction in the Soxhlet apparatus) for paclitaxel, cephalomannine, and 10-deacetylbaccatin, taxoids recovered from common yew twigs, were compared. By use of pressurised liquid extraction (PLE), the most effective extractant of taxoids was determined. HPLC was used for the analysis of the extracts. Comparison of the obtained results revealed differences in the extraction power of the applied methods. The greatest yields were obtained by multiple PLE, which can be recommended as the best sample preparation method for taxoids analysis in yew twigs.

SAXS examination of the water evaporation process from silica materials coated with a polysaccharide-polyimine copolymer layer

Abstract We present small-angle X-ray scattering (SAXS) studies of the water evaporation process from controlled porosity glass (CPG) coated with a polysaccharide–polyimine copolymers layer. The comparison of SAXS data with power law scattering and the level of scattering intensity for the material from which water is evaporated shows that SAXS is useful in defining a stage of evaporation or its degree. The results show the applicability of the SAXS method regarding the observation of changes in the thickness of the surface polymer layer during water evaporation. The possibility of estimating the polymer transition layer thickness in dried and wetted samples is an additional advantage of the SAXS method employment in the investigation of polymer–porous material systems.

How to eliminate the formation of chlorogenic acids artefacts during plants analysis? Sea sand disruption method (SSDM) in the HPLC analysis of chlorogenic acids and their native derivatives in plants

The analytical procedures for determining plant constituents involve the application of sample preparation methods to fully isolate and/or pre-concentrate the analyzed substances. High-temperature liquid extraction is still applied most frequently for this purpose. The present paper shows that high-temperature extraction cannot be applied for the analysis of chlorogenic acids (CQAs) and their derivatives in plants as it causes the CQAs transformation leading to erroneous quantitative estimations of these compounds. Experiments performed on different plants (black elder, hawthorn, nettle, yerba maté, St Johns wort and green coffee) demonstrate that the most appropriate method for the estimation of CQAs/CQAs derivatives is sea sand disruption method (SSDM) because it does not induce any transformation and/or degradation processes in the analyzed substances. Owing to the SSDM method application we found that the investigated plants, besides four main CQAs, contain sixteen CQAs derivatives, among them three quinic acids. The application of SSDM in plant analysis not only allows to establish a true concentration of individual CQAs in the examined plants but also to determine which chlorogenic acids derivatives are native plant components and what is their concentration level. What is even more important, the application of SSDM in plant analysis allows to eliminate errors that may arise or might have arisen in the study of chlorogenic acids and their derivatives in plant metabolism.

Chlorogenic acid stability in pressurized liquid extraction conditions.

Chlorogenic acids (CQAs) are phenolic compounds naturally occurring in all higher plants. They are potentially useful in pharmaceuticals, foodstuffs, food additives, and cosmetics due to their recently suggested biomedical activity. Hence, research interest in CQA properties, their isomers, and natural occurrence has been growing. Pressurized liquid extraction (PLE) is regarded as an effective and quick sample preparation method in plant analysis. The short time of PLE decreases the risk of chemical degradation of extracted compounds, thus increasing the attractiveness of its application. However, PLE applied for plant sample preparation is not free from limitations. We found that trans-5-O-caffeoylquinic acid (trans-5-CQA), the main CQA isomer, isomerizes to 3- and 4-O-caffeoylquinic acids and undergoes transesterification, hydrolysis, and reaction with water even in rapid PLE. Moreover, the number and concentration of trans-5-CQA derivatives formed in PLE strongly depends on extractant composition, its pH, and extraction time and temperature. It was not possible to find the PLE conditions in which the transformation process of trans-5-CQA would be eliminated.