基礎講座 電気泳動(Electrophoresis)

Various novel techniques including ultrasound-assisted extraction, microwave-assisted extraction, supercritical fluid extraction, and accelerated solvent extraction have been developed for the extraction of nutraceuticals from plants in order to shorten the extraction time, decrease the solvent consumption, increase the extraction yield, and enhance the quality of extracts. A critical review was conducted to introduce and compare the conventional Soxhlet extraction and the new alternative methods used for the extraction of nutraceuticals from plants. The practical issues of each extraction method were discussed. Potential uses of those methods for the extraction of nutraceuticals from plant materials was finally summarized.

Recent advances in extraction of nutraceuticals from plants

Phenolic compounds are well-known phytochemicals found in all plants. They consist of simple phenols, benzoic and cinnamic acid, coumarins, tannins, lignins, lignans and flavonoids. Substantial developments in research focused on the extraction, identification and quantification of phenolic compounds as medicinal and/or dietary molecules have occurred over the last 25 years. Organic solvent extraction is the main method used to extract phenolics. Chemical procedures are used to detect the presence of total phenolics, while spectrophotometric and chromatographic techniques are utilized to identify and quantify individual phenolic compounds. This review addresses the application of different methodologies utilized in the analysis of phenolic compounds in plant-based products, including recent technical developments in the quantification of phenolics.

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Techniques for analysis of plant phenolic compounds.

Although no randomized studies have demonstrated a positive impact of therapeutic drug monitoring (TDM) on clinical outcome in epilepsy, evidence from nonrandomized studies and everyday clinical experience does indicate that measuring serum concentrations of old and new generation antiepileptic drugs (AEDs) can have a valuable role in guiding patient management provided that concentrations are measured with a clear indication and are interpreted critically, taking into account the whole clinical context. Situations in which AED measurements are most likely to be of benefit include (1) when a person has attained the desired clinical outcome, to establish an individual therapeutic concentration which can be used at subsequent times to assess potential causes for a change in drug response; (2) as an aid in the diagnosis of clinical toxicity; (3) to assess compliance, particularly in patients with uncontrolled seizures or breakthrough seizures; (4) to guide dosage adjustment in situations associated with increased pharmacokinetic variability (e.g., children, the elderly, patients with associated diseases, drug formulation changes); (5) when a potentially important pharmacokinetic change is anticipated (e.g., in pregnancy, or when an interacting drug is added or removed); (6) to guide dose adjustments for AEDs with dose-dependent pharmacokinetics, particularly phenytoin.

/pdf/antiepileptic-drugs-best-practice-guidelines-for-therapeutic-2fvwrwdstw.pdf

Antiepileptic drugs—best practice guidelines for therapeutic drug monitoring: A position paper by the subcommission on therapeutic drug monitoring, ILAE Commission on Therapeutic Strategies

Epidemiological evidence suggests that flavonoids may play an important role in the decreased risk of chronic diseases associated with a diet rich in plant-derived foods. Flavonoids are also common constituents of plants used in traditional medicine to treat a wide range of diseases. The purpose of this article is to summarize the distribution and biological activities of one of the most common flavonoids: luteolin. This flavonoid and its glycosides are widely distributed in the plant kingdom; they are present in many plant families and have been identified in Bryophyta, Pteridophyta, Pinophyta and Magnoliophyta. Dietary sources of luteolin include, for instance, carrots, peppers, celery, olive oil, peppermint, thyme, rosemary and oregano. Preclinical studies have shown that this flavone possesses a variety of pharmacological activities, including antioxidant, anti-inflammatory, antimicrobial and anticancer activities. The ability of luteolin to inhibit angiogenesis, to induce apoptosis, to prevent carcinogenesis in animal models, to reduce tumor growth in vivo and to sensitize tumor cells to the cytotoxic effects of some anticancer drugs suggests that this flavonoid has cancer chemopreventive and chemotherapeutic potential. Modulation of ROS levels, inhibition of topoisomerases I and II, reduction of NF-kappaB and AP-1 activity, stabilization of p53, and inhibition of PI3K, STAT3, IGF1R and HER2 are possible mechanisms involved in the biological activities of luteolin.

Distribution and biological activities of the flavonoid luteolin.

The first € price and the £ and $ price are net prices, subject to local VAT. Prices indicated with * include VAT for books; the €(D) includes 7% for Germany, the €(A) includes 10% for Austria. Prices indicated with ** include VAT for electronic products; 19% for Germany, 20% for Austria. All prices exclusive of carriage charges. Prices and other details are subject to change without notice. All errors and omissions excepted. S. Nielsen (Ed.) Food Analysis

Special Issue: Food analysis.

A simple computer method for predicting the triacylglycerol composition of vegetable oils from the falty acid composition is described. The results are employed to identify the triacylglycerides present in vegetable oils such as peanut, olive, bacaba and patua pulp oils analyzed by HRGC on non-polar and polarizable columns.

Computer Prediction of Triacylglycerol Composition of Vegetable Oils by HRGC

The analysis of chemical compounds present at very low concentrations in complex matrices (e.g., residues and contaminants in food samples) usually requires a complex analytical approach, involving sampling, sample preparation, analyte isolation and qualitative and quantitative determination. Most analysts consider sample preparation to be the Achilles' heel, because it is usually time consuming, presents low yields, is prone to introducing contamination, and is more difficult to automate than other steps. Recently, a strong movement towards utilization of greener analytical methods stimulated development of microextraction techniques. Most of these microextraction techniques are based upon sorption processes, making the development of novel sorptive materials one of the most active research areas in this field. In the present work, we present a review on the new materials recently developed for sample preparation in line with the concept of green analytical chemistry. We also review the techniques using them and their main applications.

Recent advances and future trends in new materials for sample preparation

The theoretical aspects of stir bar sorptive extraction (SBSE), as well as the recent applications of this technique in pharmaceutical, biomedical, environmental, and food analysis, and recently developed new coating procedures are reviewed. A general overview of the important factors to be evaluated in the optimization of extraction efficiency such as extraction time, matrix pH, ionic strength, effect of organic additives, temperature, agitation, pre-extraction derivatization reactions, influence of proteins, and desorption conditions are discussed. An impressive number of applications using SBSE have been published in different areas including biological, environmental, and food, showing the advantages of this technique over the classical extraction techniques (liquid-liquid extraction (LLE), Soxhlet). Although the different SBSE applications use PDMS phase as sorbent, developments of new phases are necessary for specific applications. In this review, recent SBSE developments are shown with a focus on the development of new instrumental approaches and sorbent phases.

Recent developments and applications of stir bar sorptive extraction.

Advances in the area of sample preparation are significant and have been growing significantly in recent years. This initial step of the analysis is essential and must be carried out properly, consisting of a complicated procedure with multiple stages. Consequently, it corresponds to a potential source of errors and will determine, at the end of the process, either a satisfactory result or a fail. One of the advances in this field includes the miniaturization of extraction techniques based on the conventional sample preparation procedures such as liquid-liquid extraction and solid-phase extraction. These modern techniques have gained prominence in the face of traditional methods since they minimize the consumption of organic solvents and the sample volume. As another feature, it is possible to reuse the sorbents, and its coupling to chromatographic systems might be automated. The review will emphasize the main techniques based on liquid-phase microextraction, as well as those based upon the use of sorbents. The first group includes currently popular techniques such as single drop microextraction, hollow fiber liquid-phase microextraction, and dispersive liquid-liquid microextraction. In the second group, solid-phase microextraction techniques such as in-tube solid-phase microextraction, stir bar sorptive extraction, dispersive solid-phase extraction, dispersive micro solid-phase microextraction, and microextraction by packed sorbent are highlighted. These approaches, in common, aim the determination of analytes at low concentrations in complex matrices. This article describes some characteristics, recent advances, and trends on miniaturized sample preparation techniques, as well as their current applications in food, environmental, and bioanalysis fields.

Fernando Mauro Lanças

Papers

Special Issue: Food analysis.

Computer Prediction of Triacylglycerol Composition of Vegetable Oils by HRGC

Recent advances and future trends in new materials for sample preparation

Recent developments and applications of stir bar sorptive extraction.

Recent advances and trends in miniaturized sample preparation techniques