In situ antioxidation-assisted matrix solid-phase dispersion microextraction and discrimination of chiral flavonoids from citrus fruit via ion mobility quadrupole time-of-flight high-resolution mass spectrometry

Advances of Ion Mobility Platform for Plant Metabolomics

Metabolomics aims to profile the extensive array of metabolites that exists in different types of matrices using modern analytical techniques. These techniques help to separate, identify, and quantify the plethora of chemical compounds at various analytical platforms. Hence, ion mobility spectrometry (IMS) has emerged as an advanced analytical approach, exclusively owing to the 3D separation of metabolites and their isomers. Furthermore, separated metabolites are identified based on their mass fragmentation pattern and CCS (collision cross-section) values. The IMS provides an advanced alternative dimension to separate the isomeric metabolites with enhanced throughput with lesser chemical noise. Thus, the present review highlights the types, factors affecting the resolution, and applications of IMMS (Ion mobility mass spectrometry) for isomeric separations, and ionic contaminants in the plant samples. Furthermore, an overview of IMS-based applications for the identification of plant metabolites (volatile and non-volatile) over the last few decades has been discussed, followed by future assumptions for creating IM-based databases. Such approaches could be significant to accelerate and improve our knowledge of the vast chemical diversity found in plants.

Application of deep eutectic solvents on extraction of flavonoids

Deep eutectic solvents (DESs), as a new type of eco-friendly solvent, have attracted increasing attention on the extraction and separation of flavonoid compounds from various samples, owing to their excellent properties such as biodegradability and ease of handling with very low toxicity. This article provides a status review of the applications of DESs in the extraction of flavonoids, including the introduction of flavonoid compounds, the properties and superiority of DESs, and extraction methods (ultrasonic-assisted extraction, heating reflux extraction, matrix solid-phase dispersion, and solid-phase extraction). Finally, prospects and challenges in the application of DESs on extraction and separation are extensively elucidated and critically reviewed.

Improving the geographical origin classification of Radix glycyrrhizae (licorice) through hyperspectral imaging assisted by U-Net fine structure recognition

Radix glycyrrhizae (licorice) is extensively employed in traditional Chinese medicine, and serves as a crucial raw material in industries such as food and cosmetics. The quality of licorice from different origins varies greatly, so classification of its geographical origin is particularly important. This study proposes a technique for fine structure recognition and segmentation of hyperspectral images of licorice using deep learning U-Net neural networks to segment the tissue structure patterns (phloem, xylem, and pith). Firstly, the three partitions were separately labeled using the Labelme tool, which was utilized to train the U-Net model. Secondly, the obtained optimal U-Net model was applied to predict three partitions of all samples. Lastly, various machine learning models (LDA, SVM, and PLS-DA) were trained based on segmented hyperspectral data. In addition, a threshold method and a circumcircle method were applied to segment licorice hyperspectral images for comparison. The results revealed that compared with the threshold segmentation method (which yielded SVM classifier accuracies of 99.17%, 91.15%, and 92.50% on the training set, validation set, and test set, respectively), the U-Net segmentation method significantly enhanced the accuracy of origin classification (99.06%, 94.72% and 96.07%). Conversely, the circumcircle segmentation method did not effectively improve the accuracy of origin classification (99.65%, 91.16% and 92.13%). By integrating Raman imaging of licorice, it can be inferred that the U-Net model, designed for region segmentation based on the inherent tissue structure of licorice, can effectively improve the accuracy origin classification, which has positive significance in the development of intelligence and information technology of Chinese medicine quality control.

Comparative flavonoid profile of orange (Citrus sinensis) flavedo and albedo extracted by conventional and emerging techniques using UPLC-IMS-MS, chemometrics and antioxidant effects

Introduction

Citrus fruits are one of the most frequently counterfeited processed products in the world. In the juice production alone, the peels, divided into flavedo and albedo, are the main waste product. The extracts of this by-product are enriched with many bioactive substances. Newer extraction techniques generally have milder extraction conditions with simultaneous improvement of the extraction process.

Methods

This study presents a combinatorial approach utilizing data-independent acquisition-based ion mobility spectrometry coupled to tandem mass spectrometry. Integrating orthogonal collision cross section (CCS) data matching simultaneously improves the confidence in metabolite identification in flavedo and albedo tissues from Citrus sinensis. Furthermore, four different extraction approaches [conventional, ultrasonic, High Hydrostatic Pressure (HHP) and Pulsed Electric Field (PEF)] with various optimized processing conditions were compared in terms of antioxidant effects and flavonoid profile particularly polymethoxy flavones (PMFs).

Results

A total number of 57 metabolites were identified, 15 of which were present in both flavedo and albedo, forming a good qualitative overlapping of distributed flavonoids. For flavedo samples, the antioxidant activity was higher for PEF and HHP treated samples compared to other extraction methods. However, ethyl acetate extract exhibited the highest antioxidant effects in albedo samples attributed to different qualitative composition content rather than various quantities of same metabolites. The optimum processing conditions for albedo extraction using HHP and PEF were 200 MPa and 15 kJ/kg at 10 kV, respectively. While, HHP at medium pressure (400 MPa) and PEF at 15 kJ/kg/3 kV were the optimum conditions for flavedo extraction.

Conclusion

Chemometric analysis of the dataset indicated that orange flavedo can be a valid source of soluble phenolic compounds especially PMFs. In order to achieve cross-application of production, future study should concentrate on how citrus PMFs correlate with biological engineering techniques such as breeding, genetic engineering, and fermentation engineering.

3D-QSAR studies on the structure-bitterness analysis of citrus flavonoids

Despite their important bioactivities, the unpleasant bitter taste of citrus derived flavonoids limits their applications in the food industry, and the structure-bitterness relationship of flavonoids is still far from clear. In this study, 26 flavonoids were characterized by their bitterness threshold and their common skeleton using sensory evaluation and molecular superposition, respectively. The quantitative conformational relationship of the structure-bitterness of flavonoids was explored using 3D-QSAR based on comparative molecular field analysis (CoMFA) and comparative molecular similarity index analysis (CoMSIA). The results showed that increases of a hydrogen bond donor at A-5 or B-3', a bulky group at A-8, or an electron-withdrawing group at B-4' would enhance the bitterness of flavonoids. The bitterness of some flavonoids was predicted and evaluated, and the results were similar to the bitter intensity of the counterparts from the 3D-QSAR and contour plots, confirming the validation of 3D-QSAR. This study explains the theory of the structure-bitterness relationship of flavonoids, by showing potential information for understanding the bitterness in citrus flavonoids and developing a debittering process.

Simultaneous extraction and determination of alkaloids and organic acids in Uncariae Ramulas Cum Unicis by vortex-assisted matrix solid phase dispersion extraction coupled with UHPLC-MS/MS

A simple and efficient vortex-assisted matrix solid phase dispersion with a ultra-high-performance liquid chromatography-triple quadrupole mass spectrometer (VA-MSPD-UHPLC-MS/MS) was applied for simultaneous extraction and determination of seven alkaloids and three organic acids from Uncariae Ramulas Cum Unicis. The optimal extraction conditions of the target components were obtained by Box-Behnken design (BBD) combined with response surface methodology (RSM). The results of the method validation showed that this analytical method displayed good linearity with a correlation coefficient (r) no lower than 0.9990. The recoveries of ten active ingredients from Uncariae Ramulas Cum Unicis ranged from 95.9% to 103% (RSD ≤ 2.77%). The RSDs of intra-day and inter-day precisions were all below 2.97%. The present method exhibited not only lower solvent and sample usage, but also shorter sample processing and analysis time. Consequently, the developed VA-MSPD-UHPLC-MS/MS method could be successfully and effectively used for the extraction and analysis of ten active components from Uncariae Ramulas Cum Unicis.

Biological Evaluation of Valeriana Extracts from Argentina with Potent Cholinesterase Inhibition for the Treatment of Neurodegenerative Disorders and Their Comorbidities-The Case of Valeriana carnosa Sm. (Caprifoliaceae) Studied in Mice

Alzheimer's disease (AD) is a neurodegenerative disorder whose pathophysiology includes the abnormal accumulation of proteins (e.g., β-amyloid), oxidative stress, and alterations in neurotransmitter levels, mainly acetylcholine. Here we present a comparative study of the effect of extracts obtained from endemic Argentinian species of valerians, namely V. carnosa Sm., V. clarionifolia Phil. and V. macrorhiza Poepp. ex DC from Patagonia and V. ferax (Griseb.) Höck and V. effusa Griseb., on different AD-related biological targets. Of these anxiolytic, sedative and sleep-inducing valerians, V. carnosa proved the most promising and was assayed in vivo. All valerians inhibited acetylcholinesterase (IC₅₀ between 1.08-12.69 mg/mL) and butyrylcholinesterase (IC₅₀ between 0.0019-1.46 mg/mL). They also inhibited the aggregation of β-amyloid peptide, were able to chelate Fe²⁺ ions, and exhibited a direct relationship between antioxidant capacity and phenolic content. Moreover, V. carnosa was able to inhibit human monoamine oxidase A (IC₅₀: 0.286 mg/mL (0.213-0.384)). A daily intake of aqueous V. carnosa extract by male Swiss mice (50 and 150 mg/kg/day) resulted in anxiolytic and antidepressant-like behavior and improved spatial memory. In addition, decreased AChE activity and oxidative stress markers were observed in treated mouse brains. Our studies contribute to the development of indigenous herbal medicines as therapeutic agents for AD.

Applications of ion mobility-mass spectrometry in the chemical analysis in traditional Chinese medicines

离子淌度质谱(IM-MS)是一种将离子淌度分离与质谱分析相结合的新型分析技术。IM-MS的主要优势不仅是在质谱检测前提供了基于气相离子形状、大小、电荷数等因素的多一维分离,而且能够提供碰撞截面积、漂移时间等质谱信息进而辅助化合物鉴定。近年来,随着IM-MS技术的不断发展,该技术在中药化学成分分析中受到越来越多的关注。首先,IM-MS已成功应用于改善中药复杂成分尤其是同分异构体或等量异位素等成分的分离;其次,IM-MS可通过多重碎裂模式辅助高质量中药小分子质谱信息的获取;此外,IM-MS提供的高维质谱数据信息还可促进中药复杂体系多成分的整合分析。该文在对IM-MS分类和基本原理进行概述的基础上,从分离能力及分离策略、多重碎裂模式、多维质谱数据处理策略3个方面,重点综述了IM-MS在中药化学成分分析中的应用,以期为IM-MS在中药化学成分研究提供参考。

Facile and Selective Determination of Total Phthalic Acid Esters Level in Soft Drinks by Molecular Fluorescence Based on Petroleum Ether Microextraction and Selective Derivation by H2SO4

Determining the level of phthalic acid esters (PAEs) in packaged carbonated beverages is a current need to ensure food safety. High-selectivity and -accuracy identification of individual PAEs can be achieved by chromatographic and mass spectrometric (MS) techniques. However, these methods are slow; involve complicated, expensive instruments in professional laboratories; and consume a large amount of organic solvents. As such, a food analysis method is needed to conveniently and rapidly evaluate multiple contaminants on site. In this study, with the assistance of ultrasound, we quickly determined the total PAEs in soft drinks using 1.5 mL of petroleum ether in one step. Then, we determined the characteristic molecular fluorescence spectrum of all PAEs in samples (excitation (Ex)/emission (Em) at 218/351 nm) using selectively concentrated sulfuric acid derivatization. The relative standard deviations of the fluorescent intensities of mixed solutions with five different PAEs were lower than 7.1% at three concentration levels. The limit of detection of the proposed method is 0.10 μmol L−1, which matches that of some of the chromatographic methods, but the proposed method uses less organic solvent and cheaper instruments. These microextraction devices and the fluorescence spectrometer are portable and provide an instant result, which shows promise for the evaluation of the total level of PAEs in beverages on site. The proposed method successfully detected the total level of PAEs in 38 kinds of soft drink samples from local supermarkets, indicating its potential for applications in the packaged beverage industry.

The Potential of Microextraction Techniques for the Analysis of Bioactive Compounds in Food

For a long time, the importance of sample preparation and extraction in the analytical performance of the most diverse methodologies have been neglected. Cumbersome techniques, involving high sample and solvent volumes have been gradually miniaturized from solid-phase and liquid-liquid extractions formats and microextractions approaches are becoming the standard in different fields of research. In this context, this review is devoted to the analysis of bioactive compounds in foods using different microextraction approaches reported in the literature since 2015. But microextraction also represents an opportunity to mitigate the environmental impact of organic solvents usage, as well as lab equipment. For this reason, in the recent literature, phenolics and alkaloids extraction from fruits, medicinal herbs, juices, and coffee using different miniaturized formats of solid-phase extraction and liquid-liquid microextraction are the most popular applications. However, more ambitious analytical limits are continuously being reported and emergent sorbents based on carbon nanotubes and magnetic nanoparticles will certainly contribute to this trend. Additionally, ionic liquids and deep eutectic solvents constitute already the most recent forefront of innovation, substituting organic solvents and further improving the current microextraction approaches.

Towards Adsorptive Enrichment of Flavonoids from Honey Using h-BN Monolayer

Density functional theory (DFT) was used to explore the possibility of h-BN monolayer acting as an adsorbent for the flavonoids. Four flavonoids named apigenin, kaempferol, myricetin, and quercetin as well as glucose (Glu) were selected as representatives of honey. DFT and ab initio molecular dynamics simulation results show that the four flavonoids interact with the h-BN monolayer much stronger than the Glu does in both vacuum and solutions, indicating a good adsorptive selectivity of the flavonoids over Glu. The interaction of the flavonoids and the Glu with water as well as the solvation energy of the flavonoids in water, methanol and ethanol was obtained using both the PBE-D and B3LYP-D functionals. It is shown that the h-BN monolayer can provide high selective adsorption of the flavonoids from bee honey and ethanol can be used as an elution solvent to recover the adsorbed flavonoids.

Rapid Discrimination of Citrus reticulata 'Chachi' by Electrospray Ionization-Ion Mobility-High-Resolution Mass Spectrometry

A common idea is that some dishonest businessmen often disguise Citrus reticulata Blanco varieties as Citrus reticulata 'Chachi', which places consumers at risk of economic losses. In this work, we combined high-resolution ion mobility (U-shaped mobility analyzer) with high-resolution mass spectrometry to rapidly distinguish Citrus reticulata 'Chachi' from other Citrus species. The samples were analyzed directly through simple extraction and the analytes were separated in one second. It only took about 1 min to perform a cycle of sample analysis and data acquisition. The results showed that polymethoxylated flavones and their isomers were separated easily by the ion mobility analyzer and preliminarily identified according to the accurate mass. Moreover, the collision cross-section values of all analytes, which could be used as auxiliary parameters to characterize and identify the compounds in the samples, were measured. Twenty-four samples were grouped as two clusters by multivariate analysis, which meant that Citrus reticulata 'Chachi' could be effectively differentiated. It was confirmed that the developed method had the potential to rapidly separate polymethoxylated flavones and distinguish between Citrus reticulata 'Chachi' and other Citrus reticulata Blanco varieties.

Cyclodextrin-based dispersive liquid-liquid microextraction for the determination of fungicides in water, juice, and vinegar samples via HPLC

Cyclodextrin-based dispersive liquid-liquid microextraction (CD-DLLME) was developed for the determination of triazole and strobilurin fungicides in water, juice, and vinegar samples using high-performance liquid chromatography-diode-array detection (HPLC-DAD). Undecanol, which is a green solvent, was selected as the extraction solvent. A cyclodextrin aqueous solution was chosen as the dispersion solvent and demulsifier to avoid the use of a toxic dispersion solvent and eliminate the centrifugation step. Dispersion and phase separation were completed within 1 and 60 s, respectively. The linear range of this method was 1 to 100 µg L^-1. The limits of detection were 0.3 μg L^-1 along with the preconcentration factor of 133 and enrichment factor of 124. The recovery was 83.2% to 103.2%. This pretreatment method was fast, simple, and environmentally friendly and was successfully applied to the analysis of triazole and strobilurin fungicide residues in water, juice, and vinegar samples.