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Analytical Methods for Characterization and Isolation of Natural Products

A special issue of Molecules (ISSN 1420-3049). This special issue belongs to the section "Natural Products Chemistry".

Deadline for manuscript submissions: closed (30 April 2023) | Viewed by 19002

Special Issue Editors


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Guest Editor
Laboratory of Foodomics, Institute of Food Science Research (CIAL, CSIC-UAM), Madrid, Spain
Interests: green extraction techniques; biorefinery; bioprospection; green chemistry metrics; supercritical fluids; deep eutectic solvents; life cycle assesment
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Guest Editor
Applied Analytical Chemistry, University of Duisburg-Essen, Universitaetsstrasse 5, 45141 Essen, Germany
Interests: bioactives; characterization; chemical analysis; advanced analytical techniques

Special Issue Information

Dear Colleagues,

Natural products can provide us with a plethora of bioactive compounds. In fact, traditional medicines have used natural products, or their extracts, for healing since the beginning of humankind. However, nature is also an incredible source of toxins and venoms.

Natural products are a growing field of investigation for the development of new treatments and drugs derived from organisms of every kingdom. This includes from the simplest unicellular bacteria to the most complex eukaryote that can be imagined. In this sense, secondary metabolites of plants and algae are sources of chemical entities with enormous potential. To better understand the effects and the potential of these secondary metabolites, the evaluation of their chemical compositions is essential; however, this is quite challenging when dealing with the analytical steps of characterization since they are very complex mixtures that should be isolated from very complex matrices. Therefore, extraction and isolation steps are generally necessary. Moreover, an important trend in the last few years has been the application of green chemistry principles to these extraction and characterization processes, trying to achieve the Sustainable Development Goals (OSD https://www.un.org/sustainabledevelopment/). Therefore, the environmental and social impacts can be taken into account and quantified.

In this regard, this Special Issue is a unique opportunity to gather state-of-the-art analytical methods and isolation techniques applied to natural products. This topic involves scientific communities working in the extraction of bioactives, bioprospection, ethnopharmacology, folk medicine, natural toxins, or food contaminants and also involves those laboratories working on the revalorization and characterization of bioactive phytochemicals from any natural products and wastes.

The aim of this Special Issue is to present the state of the art of the sample preparation and analytical methodologies developed for monitoring the presence of pesticides and chemical residues in agrifood matrices, and to investigate bioactive phytochemicals from agrifood matrices, byproducts and wastes, providing an overview of the main trends in the area. The topics include but are not limited to the following:

- Advances in sample preparation;

- Green analytical chemistry applied to natural products;

- Chromatographic and nonchromatographic analytical techniques;

- Electroseparations;

- Spectrometrical and spectrochemical techniques;

- Chemometrical optimization;

- Pollutants in natural products: organic, inorganic and toxins;

- Bioactive compounds in natural products;

- Analytical chemistry in agrifood waste valorization;

- Bioprospection and biorefinery;

- Novel solvents in natural product analysis and extraction;

- Green metrics applied to the isolation of natural products;

- Omic approaches;

- Multidimensional separations;

- The integration of extraction techniques;

- The integration of extraction and analytical techniques.

Dr. Jose A. Mendiola
Dr. Lidia Montero
Guest Editors

Manuscript Submission Information

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Keywords

  • Advances in sample preparation
  • Green analytical chemistry applied to natural products
  • Chromatographic and nonchromatographic techniques
  • Electroseparations
  • Spectrometrical and spectrochemical techniques
  • Chemometrical optimization
  • Pollutants in natural products: organic, inorganic and toxins
  • Bioactive compounds in natural products
  • Analytical chemistry in agrifood waste valorization
  • Bioprospection and biorefinery
  • Novel solvents in natural product analysis and extraction
  • Green metrics applied to the isolation of natural products
  • Secondary metabolites
  • Omic approaches
  • Multidimensional separations

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Published Papers (7 papers)

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Research

16 pages, 3986 KiB  
Article
Optimization and Validation of a Method to Determine Enolones and Vanillin Derivatives in Wines—Occurrence in Spanish Red Wines and Mistelles
by Mónica Bueno, Julián Zapata, Laura Culleré, Ernesto Franco-Luesma, Arancha de-la-Fuente-Blanco and Vicente Ferreira
Molecules 2023, 28(10), 4228; https://doi.org/10.3390/molecules28104228 - 22 May 2023
Cited by 2 | Viewed by 1706
Abstract
Understanding the chemical nature of wine aroma demands accurate quantitative determinations of different odor-active compounds. Quantitative determinations of enolones (maltol, furaneol, homofuraneol, and sotolon) and vanillin derivatives (vanillin, methyl vanillate, ethyl vanillate, and acetovanillone) at low concentrations are complicated due to their high [...] Read more.
Understanding the chemical nature of wine aroma demands accurate quantitative determinations of different odor-active compounds. Quantitative determinations of enolones (maltol, furaneol, homofuraneol, and sotolon) and vanillin derivatives (vanillin, methyl vanillate, ethyl vanillate, and acetovanillone) at low concentrations are complicated due to their high polarity. For this reason, this paper presents an improved and automated version for the accurate measure of these common trace wine polar compounds (enolones and vanillin derivatives). As a result, a faster and more user-friendly method with a reduction of organic solvents and resins was developed and validated. The optimization of some stages of the solid phase extraction (SPE) process, such as washing with an aqueous solution containing 1% NaHCO3 at pH 8, led to cleaner extracts and solved interference problems. Due to the polarity of these type of compounds, an optimization of the large volume injection was also carried out. Finally, a programmable temperature vaporization (PTV) quartz glass inlet liner without wool was used. The injector temperature was raised to 300 °C in addition to applying a pressure pulse of 180 kPa for 4 min. Matrix effects were solved by the use of adequate internal standards, such as ethyl maltol and 3′,4′-(methylenedioxy)acetophenone. Method figures of merit were highly satisfactory: good linearity (r2 > 0.98), precision (relative standard deviation, RSD < 10%), high recovery (RSD > 89%), and low detection limits (<0.7 μg/L). Enolones and vanillin derivatives are associated with wine aging. For this reason, the methodology was successfully applied to the quantification of these compounds in 16 Spanish red wines and 12 mistelles. Odor activity values (OAV) indicate that furaneol should be considered an aroma impact odorant in red wines and mistelles (OAV > 1) while homofuraneol and sotolon could also produce changes in their aroma perceptions (0.1 < OAV < 1). Full article
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9 pages, 2118 KiB  
Article
Croargoids A–G, Eudesmane Sesquiterpenes from the Bark of Croton argyratus
by Min Wu, Kai-Long Ji, Peng Sun, Jian-Mei Lu, Jia-Rui Yue, Dong-Hua Cao, Chun-Fen Xiao and You-Kai Xu
Molecules 2022, 27(19), 6397; https://doi.org/10.3390/molecules27196397 - 27 Sep 2022
Cited by 2 | Viewed by 1504
Abstract
Seven new sesquiterpenes, named croargoid A–G (17), were isolated from the bark of Croton argyratus. Compounds 14 were the first examples of eudesmane sesquiterpene lactones containing C5-OH group. Compound 7 was a highly degraded [...] Read more.
Seven new sesquiterpenes, named croargoid A–G (17), were isolated from the bark of Croton argyratus. Compounds 14 were the first examples of eudesmane sesquiterpene lactones containing C5-OH group. Compound 7 was a highly degraded eudesmane sesquiterpene possessing a rare eleven-carbon skeleton. Their structures with stereochemistry were mainly elucidated by NMR analyses in combination with MS and ECD data. Cytotoxicities and NO inhibitions of all isolates were evaluated and only compound 5 showed moderate NO inhibitory activity. Full article
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15 pages, 2373 KiB  
Article
Chemical Constituent Analysis of Ranunculus sceleratus L. Using Ultra-High-Performance Liquid Chromatography Coupled with Quadrupole-Orbitrap High-Resolution Mass Spectrometry
by Shanshan Cao, Min Hu, Lingli Yang, Meiqin Li, Zhen Shi, Wenming Cheng, Yazhong Zhang, Fei Chen, Sheng Wang and Qunlin Zhang
Molecules 2022, 27(10), 3299; https://doi.org/10.3390/molecules27103299 - 20 May 2022
Cited by 8 | Viewed by 2518
Abstract
Ranunculus sceleratus L.(RS) has shown various pharmacological effects in traditional Chinese medicine. In our previous study, the positive therapeutic effect on α-naphthylisothiocyanate induced intrahepatic cholestasis in rats was obtained using TianJiu treatment with fresh RS. However, the chemical profile of RS has not [...] Read more.
Ranunculus sceleratus L.(RS) has shown various pharmacological effects in traditional Chinese medicine. In our previous study, the positive therapeutic effect on α-naphthylisothiocyanate induced intrahepatic cholestasis in rats was obtained using TianJiu treatment with fresh RS. However, the chemical profile of RS has not been clearly clarified, which impedes the research progress on the therapeutic effect of RS. Herein, an ultra-high performance liquid chromatography coupled with quadrupole Orbitrap high-resolution mass spectrometry (UHPLC-Q-Orbitrap HRMS) method was developed to rapidly separate and identify multiple constituents in the 80% methanol extract of RS. A total of sixty-nine compounds (19 flavonoids, 22 organic acids, 6 coumarins, 4 lignans, 14 nitrogenous compounds, and 4 anthraquinones) were successfully characterized. A total of 12 of these compounds were unambiguously identified by standard samples. Their mass spectrometric fragmentation pathways were investigated. It is worth noting that flavonoids and lignans were identified for the first time in RS. In this study, we successfully provide the first comprehensive report on identifying major chemical constituents in RS by UHPLC-Q-Orbitrap HRMS. The obtained results enrich the RS chemical profile, paving the way for further phytochemical study, quality control, and pharmacological investigation of RS. Full article
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23 pages, 3685 KiB  
Article
Systematic Screening of Chemical Constituents in the Traditional Chinese Medicine Arnebiae Radix by UHPLC-Q-Exactive Orbitrap Mass Spectrometry
by Lian Zhu, Shengjun Ma, Kailin Li, Pei Xiong, Shihan Qin and Wei Cai
Molecules 2022, 27(9), 2631; https://doi.org/10.3390/molecules27092631 - 19 Apr 2022
Cited by 16 | Viewed by 3146
Abstract
Arnebiae Radix (dried root of Arnebia euchroma (Royle) Johnst.) has been used in traditional Chinese medicine (TCM) to treat macular eruptions, measles, sore throat, carbuncles, burns, skin ulcers, and inflammation. Previous studies have shown that shikonins and shikonofurans are two of their main [...] Read more.
Arnebiae Radix (dried root of Arnebia euchroma (Royle) Johnst.) has been used in traditional Chinese medicine (TCM) to treat macular eruptions, measles, sore throat, carbuncles, burns, skin ulcers, and inflammation. Previous studies have shown that shikonins and shikonofurans are two of their main bioactive ingredients. However, systematic investigations of their constituents have rarely been conducted. It is necessary to establish a rapid and effective method to identify the chemical constituents of Arnebiae Radix. This will help to further improve the effective resource utilization rate of this plant. In this study, a rapid and effective UHPLC-Q-Exactive Orbitrap mass spectrometry method was established to simultaneously analyze chemical ingredients in Arnebiae Radix within a short period of time. Based on the results of a full scan MS, the MS2 database (mzVault and mzCloud), the diagnostic fragment ions, the retention time, and the bibliography, a total of 188 compounds were identified, with 114 of those being reported from Arnebiae Radix for the first time. The results of this study lay the foundation for obtaining a thorough understanding of the active ingredients in Arnebiae Radix and its quality control. This method may be widely used for the chemical characterization of different samples. Full article
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15 pages, 4226 KiB  
Article
Purification, Structural Characterization, and Anti-Inflammatory Effects of a Novel Polysaccharide Isolated from Orostachys fimbriata
by Datong Hu, Fan Su, Gan Yang, Jing Wang and Yingying Zhang
Molecules 2021, 26(23), 7116; https://doi.org/10.3390/molecules26237116 - 24 Nov 2021
Cited by 9 | Viewed by 2441
Abstract
The present study elucidated the structural characteristics and anti-inflammatory activity of a novel polysaccharide isolated from Orostachys fimbriata, which is a traditional Chinese medicinal plant. O. fimbriata polysaccharide (OFP) was extracted and subsequently purified by chromatography using a DEAE cellulose-52 and Sephadex [...] Read more.
The present study elucidated the structural characteristics and anti-inflammatory activity of a novel polysaccharide isolated from Orostachys fimbriata, which is a traditional Chinese medicinal plant. O. fimbriata polysaccharide (OFP) was extracted and subsequently purified by chromatography using a DEAE cellulose-52 and Sephadex G-75 column. The molecular weight was determined as 6.2 kDa. HPGPC and monosaccharide composition analysis revealed a homogeneous polysaccharide containing only Glc. Chromatography and spectral analysis showed that the possible chemical structure consisted of →4)-α-Glcp-(1→ and a small quantity of →4,6)-β-Glcp-(1→ in the main chain and →6)-β-Glcp-(1→, α-Glcp-(1→, and β-Glcp-(1→ in the side chain. Morphological analysis using scanning electron microscopy (SEM) and atomic force microscopy (AFM) indicated that OFP had a multi-branched structure, and the sugar chain molecules of polysaccharide appeared aggregated. OFP was found to exhibit anti-inflammatory activity by reducing the secretion of inflammatory factors in RAW264.7 cells and by decreasing the extent of xylene-induced ear swelling in mice. Full article
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14 pages, 8121 KiB  
Article
Optimization of Pressurized Liquid Extraction and In Vitro Neuroprotective Evaluation of Ammodaucus leucotrichus. Untargeted Metabolomics Analysis by UHPLC-MS/MS
by Norelhouda Abderrezag, Jose David Sánchez-Martínez, Ouahida Louaer, Abdeslam-Hassen Meniai and Jose A. Mendiola
Molecules 2021, 26(22), 6951; https://doi.org/10.3390/molecules26226951 - 17 Nov 2021
Cited by 7 | Viewed by 2741
Abstract
Ammodaucus leucotrichus is a spontaneous plant endemic of the North African region. An efficient selective pressurized liquid extraction (PLE) method was optimized to concentrate neuroprotective extracts from A. leucotrichus fruits. Green solvents were tested, namely ethanol and water, within a range of temperatures [...] Read more.
Ammodaucus leucotrichus is a spontaneous plant endemic of the North African region. An efficient selective pressurized liquid extraction (PLE) method was optimized to concentrate neuroprotective extracts from A. leucotrichus fruits. Green solvents were tested, namely ethanol and water, within a range of temperatures between 40 to 180 °C. Total carbohydrates and total phenolics were measured in extracts, as well as in vitro antioxidant capacity (DPPH radical scavenging), anticholinesterase (AChE) and anti-inflammatory (LOX) activities. Metabolite profiling was carried out by ultra-high-performance liquid chromatography coupled to quadrupole time-of-flight tandem mass spectrometry (UHPLC-ESI-q-TOF-MS/MS), identifying 94 compounds. Multivariate analysis was performed to correlate composition with bioactivity. A remarkable effect of the temperature using water was observed: the higher temperature, the higher extraction yield, the higher total phenolic content, as well as the higher total carbohydrates content. The water extract obtained at 180 °C, 10.34 MPa and 10 min showed meaningful anti-inflammatory (IC50LOX = 39.4 µg/mL) and neuroprotective activities (IC50AChE = 55.6 µg/mL). The Principal Components Analysis (PCA) and the cluster analysis correlated these activities with the presence of carbohydrates and phenolic compounds. Full article
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15 pages, 2870 KiB  
Article
An Analytical Toolbox for Fast and Straightforward Structural Characterisation of Commercially Available Tannins
by Lili Zhen, Heiko Lange and Claudia Crestini
Molecules 2021, 26(9), 2532; https://doi.org/10.3390/molecules26092532 - 26 Apr 2021
Cited by 8 | Viewed by 3044
Abstract
Both condensed and hydrolysable tannins represent versatile natural polyphenolic structures exhibiting a broad range of activities that could be exploited in various fields including nutraceutics, cosmesis, consumer care, household and pharmaceutical applications. Various tannins are commercially available nowadays for use in such application [...] Read more.
Both condensed and hydrolysable tannins represent versatile natural polyphenolic structures exhibiting a broad range of activities that could be exploited in various fields including nutraceutics, cosmesis, consumer care, household and pharmaceutical applications. Various tannins are commercially available nowadays for use in such application fields. We have analysed a representative selection of commercially available condensed and hydrolysable tannins for structural features and purity. Using a combination of quantitative 31P NMR spectroscopy, HSQC measurements, MALDI-ToF analyses, gel permeation chromatography and wet chemical analysis, detailed structural characterisations and descriptions were possible, allowing for verification and falsification of claimed structural features. Full article
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