Ionic liquid-based ultrasound-assisted extraction coupled with liquid chromatography to determine isoflavones in soy foods

Overview of the Polyphenols in Salicornia: From Recovery to Health-Promoting Effect

Nowadays, there has been considerable attention paid toward the recovery of waste plant matrices as possible sources of functional compounds with healthy properties. In this regard, we focus our attention on Salicornia, a halophyte plant that grows abundantly on the coasts of the Mediterranean area. Salicornia is used not only as a seasoned vegetable but also in traditional medicine for its beneficial effects in protecting against diseases such as obesity, diabetes, and cancer. In numerous research studies, Salicornia consumption has been highly suggested due to its high level of bioactive molecules, among which, polyphenols are prevalent. The antioxidant and antiradical activity of polyphenols makes Salicornia a functional food candidate with potential beneficial activities for human health. Therefore, this review provides specific and compiled information for optimizing and developing new extraction processes for the recovery of bioactive compounds from Salicornia; focusing particular attention on polyphenols and their health benefits.

Uses of ionic liquids to obtain bioactive compounds: insights from the main international regulations for technological applications

Ionic liquids (IL) are innovative alternative solvents to recover bioactive compounds from plant-based sources to replace toxic volatile organic solvents (VOS). ILs are tailored-made solvents with chemical and thermal stabilities, nonvolatile and noninflammable. Although ILs are versatile, cost-effective, and sustainable solutions, the European Commission (EC) has no current regulation to approve extracts obtained with ILs to be applied in foods. Herein, this paper aims to assess the overview of ILs, regulamentation, applications, and its toxic effects, to be used as solvents for extract different bioactive compounds. Studies have suggested novel applications for ILs, such as 1-butyl-3-methylimidazolium bromide, 1-butyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium tetrafluoroborate and others, to obtain bioactive compounds, for instance phenolic compounds, lignans, alkaloids, carotenoids, polysaccharides, using modern approaches as ultrasound and microwave-assisted extraction. New IL methods increase the efficiency of recovering target compounds and decrease the extraction time and VOS consumption regarding the traditional techniques. Furthermore, to promote the large-scale use of IL in foods, it is essential to investigate individually the toxicity of each IL used in the extraction processes, aiming to obtain a GRAS stamp, due to the currently lack of regulamentation.

The application of amino acid ionic liquids as additives in the ultrasound-assisted extraction of plant material

The aim of the present study was to determine the antioxidant activity of the aqueous extracts from Lycopodium clavatum, Cetraria islandica and Dipsacus fullonum obtained using aqueous solutions of ionic liquids by the ultrasound-assisted extraction (IL-UAE) method. Triethanolammonium salts [TEAH]⁺[AA]⁻ of four amino acids of different hydrophobicity – isoleucine – Ile, methionine – Met, threonine – Thr and arginine – Arg, were chosen as ionic liquids, because they are based on natural, bio-renewable raw materials, such as amino acids and contain a pharmaceutically and cosmetically acceptable counterion of triethanolamine. Triethanolammonium salts were synthesized, identified by spectroscopic methods (NMR and FT-IR) and characterized by thermal methods (DSC and TGA). The 2.5% w/v aqueous solutions of triethanolammonium amino acid salts were used as the solvents in combination with ultrasound assisted extraction (UAE). The estimation of antioxidant properties was carried out using the DPPH, FRAP and CUPRAC assays. Total polyphenol content was measured using the reagent Folin–Ciocalteu. The results showed that the use of [TEAH]⁺[Thr]⁻ or [TEAH]⁺[Met]⁻ aqueous solutions increased the antioxidant activity of extracts in comparison to that achieved for extracts with pure water. The use of [TEAH]⁺[Thr]⁻ as an additive for ultrasound-assisted extraction was characterized by obtaining plant extracts with the highest antioxidant potential, even 2.4-fold. The use of the AAIL-UAE method allowed obtaining higher amounts of polyphenols compared to pure water extracts, even 5.5-fold. The used method allowed the extraction of thermosensitive natural compounds, shortened the extraction time and lowered energy consumption.

The antioxidant activity of the aqueous extracts from Lycopodium clavatum, Cetraria islandica and Dipsacus fullonum obtained by ionic liquids and ultrasound-assisted extraction (IL-UAE) method was determined.

Advanced Analytical Approaches for the Analysis of Polyphenols in Plants Matrices—A Review

Phenolic compounds are plants’ bioactive metabolites that have been studied for their ability to confer extensive benefits to human health. As currently there is an increased interest in natural compounds identification and characterization, new analytical methods based on advanced technologies have been developed. This paper summarizes current advances in the state of the art for polyphenols identification and quantification. Analytical techniques ranging from high-pressure liquid chromatography to hyphenated spectrometric methods are discussed. The topic of high-resolution mass spectrometry, from targeted quantification to untargeted comprehensive chemical profiling, is particularly addressed. Structure elucidation is one of the important steps for natural products research. Mass spectral data handling approaches, including acquisition mode selection, accurate mass measurements, elemental composition, mass spectral library search algorithms and structure confirmation through mass fragmentation pathways, are discussed.

Analysis of Zinc and Chromium in Grain Samples Using Ionic Liquid-Based Ultrasound-Assisted Microextraction Followed by Flame-AAS After Microwave Digestion

A simple, rapid and eco-friendly microextraction method was developed for the determination and preconcentration of zinc (Zn) and chromium (Cr) from grain products by ultrasonic-assisted ionic liquid dispersive liquid-liquid microextraction (UA-IL-DLLME) combined with flame atomic absorption spectrometry (FAAS). Quercetin (2-(3,4-dihydroxyphenyl)-3,5,7-trihydroxy-4H-chromen-4-one dihydrate) was used for the complexation of Zn(II) and Cr(III) ions at different pHs. The 1-hexyl-3-methylimidazolium bis[(trifluoromethyl) sulfonyl]imide ([Hmim][NTf2] and acetonitrile were used as extraction solvent and dispersive solvent, respectively. To provide quantitative extraction of analytes, important experimental variables such as pH of sample solution, temperature, ultrasonic time, amount of chelating agent, amount of ionic liquid, type and amount of dispersive solvent, and interference effect were extensively studied and optimized. The detection limits and operating ranges for Zn(II) and Cr(III) using the optimized conditions were 7.5, 25-450 and 2.4, 8-300 μg L^-1, respectively. For the validation of the proposed method, the certified reference material was tested using the standard addition method. After microwave digestion analysis of grain products, relative standard deviations (RSDs%) and recoveries were ranged from 1.2 to 2.3% and from 91.2 to 103.7%, respectively. The UA-IL-DLLME method has been successfully applied for the determination of Zn and Cr in grain samples (chickpea, broad bean, pea, beans, and wheat).

The experimental design approach to the optimization of a simple quick easy cheap effective rugged and safe method for the analysis of phytoestrogens in complex soy-based food

The present paper deals with the multivariate optimization of an extraction-purification strategy for the determination of phytoestrogens (daidzein, genistein, coumestrol, formononetin, and biochanin A) in soy-based meat substitutes by high performance liquid chromatography with tandem mass spectrometry. For a reliable quantitation of these new concerning compounds in such a complex matrix, recovery and matrix effect must be carefully evaluated. Therefore, two sequential experimental designs were used to optimize the sample-pretreatment of soy-based burgers: the chosen technique was the quick, easy, cheap, effective, rugged and safe methodology, which does not require any particular facility or instrumentation. Thanks to the first screening design (Plackett-Burman), the significant factors influencing the studied responses were identified and further investigated through a response surface design (Box-Behnken). The optimal values of the variables (volume of extraction solvent mix/sample mass ratio and two clean-up sorbents) led to quantitative recoveries (97-104%) and low ion suppression (matrix effect 60-93%) for all analytes. This optimized method was characterized by low detection limits (0.2-1.5 ng/g) and excellent intraday precision (RSD 2-4%). It was applied to the determination of the considered compounds in several soy-burgers from the Italian market, detecting low ng/g levels (up to 40 ng/g) of coumestrol, formononetin, and biochanin A, and high concentrations (7.9-78 µg/g) of genistein and daidzein.

Vesicle based ultrasonic-assisted extraction of saponins in Panax notoginseng

A simple and effective vesicle based ultrasonic-assisted extraction (UAE) method was developed for extraction of active compounds in functional food. The target analytes were determined by ultra-high performance liquid chromatography with ultraviolet detector. Surfactant vesicle was adopted as extraction solvent. Different operating conditions including the type and concentration of vesicle, extraction time and solid to liquid ratio were investigated by single-factor experiments and response surface methodology. Optimized experimental conditions were 1% (w/v) of DTAB/SDS vesicle, 20 min of extraction time and 160 mg/mL of solid to liquid ratio. The proposed method provided good linearity in the linear range of 10-1000 μg/mL with regression coefficients larger than 0.999, low limits of detection of 27.64-55.67 ng/mL, good precision with relative standard deviations below 0.35%, and satisfactory recoveries of 83.84-90.92% for tested saponins. Consequently, the proposed vesicle based UAE method was well suited for the extraction of saponins in Panax notoginseng.

Soy Isoflavones and their Effects on Xenobiotic Metabolism

BACKGROUND

Soy isoflavones, such as genistein and daidzein, are bioflavonoids found in soy products that are able to interact with various hormones such as estrogen. Epidemiological studies reveal a proper level of isoflavones in diet can prevent many diseases like cancers or diabetes. Therefore, it is important to study the biotransformation and xenobiotic metabolism of soy isoflavones.

METHODS

A systematic review of published studies was carried out to investigate the characterization of isoflavones and their metabolites, sample pretreatment and quantitative analysis of isoflavones, and the influence of soy isoflavones on drug and xenobiotic metabolism.

RESULTS

Aglycones with weak estrogen-like activities are the biologically active forms of the soy isoflavones in mammals. The most recent advances including extraction, purification and detection of isoflavones in soybean and soy products are discussed. The effects of soy isoflavones on drug and xenobiotic metabolism involve in regulation of phase I cytochrome P450 (CYPs) enzyme and phase I detoxifying enzymes expression and activity. At the molecular level, soy isoflavones have proved capable of estrogenic/antiestrogenic with tissue-selective, anti-cancer, antiobesity, anti-oxidation, and tyrosine kinase inhibition activities.

CONCLUSION

This review summarized different aspects of soy isoflavones and their molecular mechanisms of pharmacological action on xenobiotic, which demonstrated that soy isoflavones can decrease the incidence of many diseases and benefit for human health. However, since the lack of clinical research for evaluation of the proper dosage of intake of soy isoflavones in diet or adjunctive therapy, there is a need for further studies on the selection of doses, biomedical applications and adverse effects of isoflavones for human health.

Phytoestrogens in soy-based meat substitutes: Comparison of different extraction methods for the subsequent analysis by liquid chromatography-tandem mass spectrometry

This paper presents the development of an efficient extraction procedure followed by a high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method for the determination of five phytoestrogens (genistein, daidzein, formononetin, biochanin A, and coumestrol) in soy-based meat substitutes. Phytoestrogens are considered endocrine disrupting compounds, and their quantification is important in soy-based products, whose diffusion is increasing nowadays. The HPLC-MS/MS method, with electrospray ionization (ESI) source, was optimized to obtain high specificity and sensitivity, as well as rapidity of the analysis. Three extraction techniques were applied to soy burgers and compared: ultrasound assisted extraction, ultrasound assisted extraction followed by solid phase extraction and the Quick Easy Cheap Effective Rugged and Safe (QuEChERS) methodology. Both ultrasound assisted extraction and QuEChERS proved to be suitable for the determination of phytoestrogens, showing high recoveries, in the range of 86% to 99% and 75% to 105%, respectively. Matrix effect was evaluated, and ion suppression was observed for coumestrol and formononetin, demonstrating the importance of matrix effect assessment when complex samples are analyzed by HPLC-ESI-MS. The complete analytical protocols provided limits of detection and quantitation in soy-burgers at the ng g^-1 level for all the considered phytoestrogens. Some soy burger samples were analyzed by both ultrasound assisted extraction and QuEChERS followed by HPLC-MS/MS. High concentration levels of daidzein and genistein (2-59 μg g^-1 and 2-72 μg g^-1 , respectively) were found; formononetin was in the range of 5 to 26 ng g^-1 , while biochanin A and coumestrol were under the limit of quantitation in all samples. The results obtained with the two different sample treatment were in good agreement, proving the precision and accuracy of the described techniques.

Ionic Liquid Solutions as a Green Tool for the Extraction and Isolation of Natural Products

In the past few years, the application of ionic liquids (ILs) had attracted more attention of the researchers. Many studies focused on extracting active components from traditional herbals using ILs as alternative solvents so as to address the issue caused by the traditional methods for extraction of natural products (NPs) with organic chemical reagents. Through the summary of reported research work, an overview was presented for the application of ILs or IL-based materials in the extraction of NPs, including flavonoids, alkaloids, terpenoids, phenylpropanoids and so on. Here, we mainly describe the application of ILs to rich the extraction of critical bioactive constituents that were reported possessing multiple therapeutic effects or pharmacological activities, from medicinal plants. This review could shed some light on the wide use of ILs in the field of natural products chemistry to further reduce the environmental damage caused by large quantity of organic chemical reagents.