Comprehensive polyphenol profiling of a strawberry extract (Fragaria × ananassa) by ultra-high-performance liquid chromatography coupled with high-resolution mass spectrometry

Sugars and Organic Acids in 25 Strawberry Cultivars: Qualitative and Quantitative Evaluation

(1) The nutritional quality of strawberry (Fragaria × ananassa Duch) fruits, among others, is largely maintained by the presence of soluble sugars and organic acids. As the primary products of photosynthesis, they are energy depots in plants, necessary for the construction of cell constituents, but also serve as precursors of aromatic compounds and signaling molecules. (2) In this study, fruits of 25 strawberry cultivars were qualitatively and quantitatively characterized concerning individual sugars and organic acids by HPLC, FT-ICR-MS, and MS imaging analysis. In addition, the total quality index (TQI), as a novel mathematical model, was used to compare all individual parameters evaluated to obtain a quantitative single score, as an indicator of overall fruit quality. (3) Regardless of a large number of cultivars and monitored parameters that were studded, several cultivars stood out in terms of selected primary metabolites, such as 'Rumba', 'Jeny', and 'Sandra', while the latter had the best TQI score. (4) Intercultivar variations in sugars and organic acids profiles, along with other bioactive compounds, should be considered for selection of promising cultivars with improved naturally occurring nutraceutical traits. Besides the search for a pleasant taste, increased awareness of healthy nutrition resulted in heightening consumer demand for high-quality fruit.

Rapidly analyzing of ingredients during chewing and processing of areca nut using feature-based molecular networking

As a traditional herbal medicine and food in China and many other Asian countries, the areca nut (Areca catechu L.) is not only widely used for the treatment of various diseases, but also popular as a chewing hobby. However, as a first-class carcinogen designated by IARC, clinical studies have shown that long-term chewing of areca nut is associated with oral mucosal diseases and even oral cancer. Moreover, the incidence of these diseases varies regionally, suggesting that it may be related to edible methods in different regions. In this study, UPLC-Q-TOF-MSE was combined with feature-based molecular networking to systematically characterise the chemical ingredients of areca nut. Based on these results, the ingredients of different edible parts and edible methods was rapidly compared. The compositional changes during the production process were also analysed. The obtained results provide a foundation for the scientific utilisation of areca nut.

Detailed investigation of the composition and transformations of phenolic compounds in fresh and fermented Vaccinium floribundum berry extracts by high-resolution mass spectrometry and bioinformatics

INTRODUCTION

Blueberries are known for their very high content of biologically active phenolic compounds; nonetheless, differently from the North American and European species of blueberries, Neotropical blueberries have not been extensively studied yet.

OBJECTIVES

In the present paper, the phenolic composition of Vaccinium floribundum Kunth, which is endemic to the Andean regions and grows 1,600 to 4,500 meters above sea level, was investigated by ultra-high-performance liquid chromatography coupled to high-resolution mass spectrometry (UHPLC-HRMS). Native and fermented berries were compared in terms of phenolic composition as well as antioxidant activity, total phenolic content, and total anthocyanin content.

MATERIALS AND METHODS

V. floribundum native and fermented berries were extracted and analyzed by UHPLC-HRMS. The acquired datasets were processed by Compound Discoverer 3.1 using a dedicated data analysis workflow that was specifically set up for phenolic compound identification.

RESULTS

In total, 309 compounds were tentatively identified, including anthocyanins, flavonoids, phenolic acids, and proanthocyanidins. The molecular transformations of phenolic compounds during fermentation were comprehensively investigated for the first time, and by a customized data processing workflow, 13 quinones and quinone methides were tentatively identified in the fermented samples. Compared to other species of the genus Vaccinium, a peculiar phenolic profile is observed, with low abundance of highly methylated compounds.

CONCLUSION

Andean berries are a rich source of a wide variety of phenolic compounds. Untargeted MS analyses coupled to a dedicated data processing workflow allowed expanding the current knowledge on these berries, improving our understanding of the fate of phenolic compounds after fermentation.

Profiles of Volatile and Phenolic Compounds as Markers of Ripening Stage in Candonga Strawberries

Volatile compounds, quality traits (total phenols and antioxidant capacity) and High-performance liquid chromatography (HPLC)-isolated polyphenols of strawberries, variety Sabrosa, commercially referred to as “Candonga”, harvested at three different times (H1, H2 and H3) and at two different ripening stages, namely half-red (Half-red-H1, Half-red-H2 and Half-red-H3) and red (Red-H1, Red-H2 and Red-H3) were evaluated. Dominant anthocyanins, namely cyanidin-3-O-glucoside, pelargonidin-3-O-glucoside and pelargonidin-3-O-rutinoside, as well as p-coumaryl hexoside increased during harvesting, differently from flavonoids, such as quercetin-3-O-glucoside, kaempferol-3-O-glucoronide and quercetin 3-O-glucoronide, that declined. Samples clustered in different quadrants of the principal component analysis (PCA) performed on volatiles, quality traits and phenolic compounds, highlighting that only the red samples were directly correlated to volatile components, as volatiles clearly increased both in number and amount during ripening. In particular, volatiles with a positive impact on the consumers’ acceptance, including butyl butyrate, ethyl hexanoate, hexyl acetate, nonanal, terpenes and lactones, were positively associated with the Red-H1 and Red-H2 strawberries, while volatiles with negative coefficients related to consumer liking, including isopropyl butyrate, isoamyl butyrate and mesifurane directly correlated with the Red-H3 samples. Accordingly, strawberries harvested at Red-H1 and Red-H2 ripening stages could be preferred by the consumers compared to the Red-H3 fruit. Altogether, these results could help to individuate quality traits as putative markers of the ripening stage, and optimize the process of post-harvesting ripening to preserve or improve the desirable aromatic characteristics of strawberries.

Unique distribution of ellagitannins in ripe strawberry fruit revealed by mass spectrometry imaging

Ellagitannins (ETs) are hydrolysable tannins composed of a polyol core, primarily glucose, which is esterified with hexahydroxydiphenic acid (HHDP), and in some cases, gallic acid. ETs are the major phenolic compounds found in strawberries and may contribute to the health-related properties of strawberries, because of their strong antioxidative activity. However, their distribution in the strawberry fruit remains unclear. In this study, matrix-assisted laser desorption/ionization-mass spectrometry imaging (MALDI–MSI) was used to visualize ETs in ripe strawberry fruits. Five peaks, corresponding to the m/z values of ET [M−H]⁻ ions detected in the MALDI–MS spectrum of strawberry extracts, were identified as strictinin, pedunculagin, casuarictin, davuriicin M₁, and an unknown ET using MALDI–tandem MS (MS/MS). In addition, liquid chromatography–electrospray ionization–MS/MS of the extracts revealed the presence of pedunculagin isomers and the unknown ET. Ion images of these five ETs were reconstructed using MALDI–MSI. Strictinin was widely distributed in and around the achene seed coats, while the other ETs were dispersed in and around the seed coats, and at the bottom of the receptacle; pedunculagin was distributed in the epidermis and pith, whereas casuarictin, the unknown ET, and davuriicin M₁ were distributed in the pith. Moreover, MALDI–MSI of a casuarictin standard indicated that in-source fragmentation weakly affected the ion images. The results suggest that the distribution of ETs depends on the presence or absence of their constituents, namely galloyl units, HHDP, and bis-HHDP. To the best of my knowledge, this is the first report on the visualization of ETs in plant tissues using MSI, MALDI–MSI may be a useful tool for analyzing the distribution of ETs in the strawberry fruit.

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The ellagitannins (ETs) in strawberry fruits were identified.

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MALDI-MS/MS and LC-MS/MS were used.

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The ETs identified in the fruits were visualized using MALDI-MSI.

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The ETs showed unique distributions in the seeds and the lower receptacle.

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The distribution of ETs depends on their constituents: galloyl units and HHDP.

Andean Blueberry of the Genus Disterigma: A High-Resolution Mass Spectrometric Approach for the Comprehensive Characterization of Phenolic Compounds

Wild neotropical blueberries, endemic of Central and South American areas, are promising yet still undisclosed sources of bioactive compounds. Most research studies have addressed wild and cultivated blueberries from Europe and North America, despite the extremely wide variety of wild neotropical species. In the present paper, for the first time, the phenolic composition of Disterigma alaternoides was investigated through ultra-high-performance liquid chromatography coupled to high-resolution mass-spectrometric analysis followed by accurate data analysis and compound validation with a dedicated structure-based workflow. D. alaternoides, which belongs to a closely related genus to that of the common blueberry, grows exclusively in the Andean regions over 2000 above sea level. Thanks to the dedicated analytical platform, 249 phenolic compounds were tentatively identified, including several anthocyanins, flavonoids, phenolic acids, and proanthocyanidins. Thenature and heterogeneity of identified phenolic compounds demonstrate once more the need for a more profound knowledge of such still uncharted matrices.

Liquid Chromatographic Quadrupole Time-of-Flight Mass Spectrometric Untargeted Profiling of (Poly)phenolic Compounds in Rubus idaeus L. and Rubus occidentalis L. Fruits and Their Comparative Evaluation

This study provided a detailed profiling of the antioxidant and bioactive compounds occurring in three varieties of Rubus idaeus L. fruits (“Fall Gold”, “Glen Ample” and “Tulameen”) compared to Rubus occidentalis L. black raspberry (“Jewel” cultivar), adopting a comprehensive untargeted metabolomics approach developed with UHPLC analysis coupled with quadrupole/time-of-flight high resolution mass spectrometry, using the SWATH^® acquisition protocol. The feature selection and annotation workflow, applied to the analysis of raspberry extracts in both polarities, allowed identifying 68 bioactive compounds mainly belonging to the classes of (poly)phenolic compounds. Interestingly, some of these identifications (e.g., ferulic acid glycosides and the ellagitannin-like nobotanin/malabathrin) represent the first report in raspberry fruits. Principal component analysis made possible highlighting the features more related to the expression of a genotype effect within the R. idaeus species or between the two raspberry species herein investigated. Overall, flavanols were the most discriminating features for the Fall Gold variety, whereas ellagitannins and flavonol glycosides represent more distinctive metabolic traits in Glen Ample and Tulameen fruits. Moreover, R. occidentalis Jewel variety was strongly characterized by the occurrence of anthocyanins, such as cyanidin, pelargonidin and delphinidin glycosides.

In-depth cannabis fatty acid profiling by ultra-high performance liquid chromatography coupled to high resolution mass spectrometry

Industrial hemp (Cannabis sativa L.) represents an important plant, used for a variety of uses including pharmaceutical and nutraceutical purposes. As such, a detailed characterization of the composition of this plant could help future research to further exploit the beneficial effects of hemp compounds on the human health. Among the many compounds of hemp, fatty acids represent an interesting class of minor components, which has been overlooked so far. In this work, an untargeted approach based on liquid-chromatography coupled to a high-resolution mass spectrometry and a dedicated structure-based workflow for raw data interpretation was employed for the characterization of fatty acids from hemp inflorescences. A simple method, without any chemical derivatization, was developed for extraction and characterization of fatty acids leading to the tentative identification of 39 fatty acid species in the five hemp samples. A quantitative analysis on the untargeted data was initially performed, using peak areas as surrogate of analyte abundance for relative quantitation. Five fatty acids resulted the most abundant in all hemp samples, with ca. 90% of the total peak area. For these compounds a targeted quantitative method was validated, indicating that the most abundant ones were linolenic acid (1.39-7.95 mg g-1) and linoleic acid (1.04-7.87 mg g-1), followed by palmitic acid (3.74-6.08 mg g-1), oleic acid (0.91-4.73 mg g-1) and stearic acid (0.64-2.25 mg g-1).

Productivity and nutritional and nutraceutical value of strawberry fruits (Fragaria x ananassa Duch.) cultivated under irrigation with treated wastewaters

BACKGROUND

Agriculture represents a productive sector typically characterized by a high water demand, whereas freshwater (FW) availability is a problem of increasing concern in the world and FW resources are becoming insufficient for sustaining agricultural irrigation. The reuse of treated wastewaters (TWWs) for crop irrigation could be an efficient tool for reducing water shortage. Hence, the present study evaluated the food quality of Fragaria x ananassa (cultivar Camarosa) fruits irrigated with four types of treated wastewaters (TWWs). Strawberries were analysed for yield, sucrose, fructose, glucose, total soluble polyphenols (TSP), total monomeric anthocyanins (TMA), and antiradical and antioxidant capacity. In addition, a targeted quantification of the most representative phenolic compounds of strawberry was performed.

RESULTS

TWWs complied the Italian ministerial decree 185/2003 for wastewater reuse, with very few exceptions, mainly represented by chloride concentrations (258-643 mg L^-1 versus a legal threshold of 250 mg L^-1 ). The reuse of TWWs reduced fruit yield (10-26%) compared to irrigation with tap water as a control. Irrigation with TWWs gave also rise to the decrease of total sugars (14-26%), TSP (2-10%) and TMA (29-49%). Individual phenolic acids, flavonols and flavanols were quite stable in response to the irrigation with TWWs, whereas anthocyanidins decreased significantly.

CONCLUSION

Although TWWs negatively affected fruit quality, the nutritional and nutraceutical parameters determined in the present study were in line with data previously reported for strawberries purchased in the market or cultivated in research orchards, thus suggesting that the use of TWWs does not prevent the fruit marketability. © 2020 Society of Chemical Industry.

Untargeted Characterization of Chestnut (Castanea sativa Mill.) Shell Polyphenol Extract: A Valued Bioresource for Prostate Cancer Cell Growth Inhibition

Chestnut seeds are used for fresh consumption and for the industrial preparation of derivatives, such as chestnut flour. During industrial processing, large amounts of by-products are generally produced, such as leaves, flowers, shells and burs. In the present study, chestnut shells were extracted by boiling water in order to obtain polyphenol-rich extracts. Moreover, for the removal or non-phenolic compounds, a separation by preparative reverse phase chromatography in ten fractions was carried out. The richest fractions in terms of phenolic content were characterized by means of untargeted high-resolution mass spectrometric analysis together with a dedicated and customized data processing workflow. A total of 243 flavonoids, phenolic acids, proanthocyanidins and ellagitannins were tentatively identified in the five richest fractions. Due its high phenolic content (450.03 µg GAE per mg of fraction), one tumor cell line (DU 145) and one normal prostate epithelial cell line (PNT2) were exposed to increasing concentration of fraction 3 dry extract for 24, 48 and 72 h. Moreover, for DU 145 cell lines, increase of apoptotic cells and perturbation of cell cycle was demonstrated for the same extract. Those outcomes suggest that chestnut industrial by-products could be potentially employed as a source of bioresources.

Chemometric Characterization of Strawberries and Blueberries according to Their Phenolic Profile: Combined Effect of Cultivar and Cultivation System

Chemical characterizations of leaves and fruits that were obtained from organically and integrally produced strawberries ('Favette', 'Alba', and 'Clery') and blueberries ('Bluecrop', 'Duke', and 'Nui') from western Serbia were undertaken in this study. Phenolic analysis was done while using ultra-high performance liquid chromatography coupled to a linear ion trap-Orbitrap hybrid mass analyzer, while total phenolic content (TPC), total anthocyanin content (TAC), and radical-scavenging activity (RSA) by spectrophotometry. In general, leaves and fruits from blueberry showed higher levels of TPC and TAC as compared to strawberry. These chemical traits were larger in organic grown fruits and larger in leaves than fruits. The most abundant phenolics in leaves and fruits of blueberry was 5-O-caffeoylquinic acid, followed by quercetin 3-O-galactoside, while catechin, quercetin, and kaempferol 3-O-glucosid were dominant in the leaves and fruits of strawberry. cis, trans-Abscisic acid was detected in all fruit samples, but not in leaves. Blueberries (both fruits and leaves) were separated from strawberries, but only organic blueberry fruits were distinguished from integrated fruits, according to principal component analysis. Quercetin, kaempferol, 5-O-caffeoylquinic acid, ferulic acid, caffeic acid, catechin, p-coumaric acid, and p-hydroxybenzoic acid were the most influential phenolic compounds for the separation. Much higher contents of TPC, RSA, TAC, quercetin 3-O-galactoside, and quercetin were found in fruits and TPC, RSA, catechin, p-hydroxybenzoicacid, p-coumaricacid, and ferulic acid in leaves in all three blueberry cultivars and the strawberry cultivar 'Clery'. These phenolic compounds are good sources of antioxidant compounds with potentially high beneficial effects on human health.

A new software-assisted analytical workflow based on high-resolution mass spectrometry for the systematic study of phenolic compounds in complex matrices

Polyphenols are a broad class of plant secondary metabolites which carry out several biological functions for plant growth and protection and are of great interest as nutraceuticals for their antioxidant properties. However, due to their structural variability and complexity, the mass-spectrometric analysis of polyphenol content in plant matrices is still an issue. In this work, a novel approach for the identification of several classes of polyphenol derivatives based on ultra-high performance liquid chromatography coupled to high-resolution mass spectrometry was developed. First, mass-spectrometric parameters were optimized in order to obtain a large set of diagnostic product ions for their high-confidence identification. The software Compound Discoverer 3.0 was then implemented with a comprehensive database of 45,567 polyphenol derivatives and with mass-spectrometric data for their building blocks, resulting in a specific tool for the semi-automatic identification of flavonoids, anthocyanins, ellagitannins, proanthocyanidins and phenolic acids. The method was then applied to the identification of polyphenols in industrial hemp (Cannabis sativa), a matrix whose use is recently spreading for pharmaceutical and nutraceutical purposes, resulting in the identification of 147 compounds belonging to the classes of flavonoids, proanthocyanidins and phenolic acids. The proposed method is applicable to the polyphenol profiling of any plant matrix and it is not dependent on data in the literature for their identification, allowing the discovery of compounds which have been never identified before.

A Comprehensive Review of the Structure Elucidation of Tannins from Terminalia Linn

OBJECTIVES

Tannins with complex structures are important plant resources, which are abundant in the genus Terminalia. Various Terminalia species have been playing an important role in traditional medicine system. A systematic scoping review of Terminalia Linn. research literature for tannins was conducted to summarize the structures of tannins and analysis fragmentation pathway characteristics, which could provide references for the structural analysis of tannins from Terminalia Linn.

METHODS

After an update of the literature search up to September 2018, the terms of Terminalia in all publications were analyzed. Electronic searches were conducted in scifinder and PubMed, and the information from 197 articles in all with regard to the tannin structure study was extracted.

RESULTS

The compounds of 82 tannins from the genus Terminalia were reviewed. According to the structural differences, they can be divided into three categories, hydrolysable tannins, condensed tannins, and complex tannins, respectively. The fragmentation pathways of 46 identified tannins were analyzed, and the fragmentation rules of tannins were speculated according to different types.

CONCLUSION

This review has attracted attention to the active substances in this species such as the tannins summarized in further study. How to improve the extraction and purification technology of tannins from genus Terminalia is an urgent problem to be solved.

A comprehensive analysis of liposomal biomolecular corona upon human plasma incubation: The evolution towards the lipid corona

When drug nanocarriers enter a physiological environment, their surface gets coated by a dynamic biomolecular corona (BMC) mainly constituted by proteins. Although a deep investigation has been performed on the composition of BMC in terms of proteins, scarce attention has been posed to low molecular weight metabolites present in human plasma. In this work, for the first time, the investigation of the BMC of liposomal nanoparticles (NPs) constituted by 1,2-dioleoyl-3-trimethylammonium-propane polar lipid has been carried out by an ultra-high performance liquid chromatography coupled to high-resolution mass spectrometry based untargeted metabolomics approach. Compounds were tentatively identified based on matches with online databases and comparison of MS/MS spectra with available spectral libraries. Moreover, a comparison of three metabolite extraction strategies, including an ultrafiltration membrane based protocol, a methanol extraction based protocol, and Wessel & Flügge protocol, was performed. Methanol extraction procedure resulted in the widest metabolic coverage of liposomal NP BMC. A total of 193 metabolites has been tentatively identified, 166 of which belonged to the class of lipids including phospholipids, steroids, carnitines, fatty alcohols, diglycerides and fatty acids. The high abundance of lipids in the BMC can be explained by the adsorption of plasma lipoproteins onto liposome surface, confirming previous works on other kinds of NPs. Lipids are important bioactive molecules, which could impact NP circulation and uptake by cells. Extending the investigation of BMC beyond the protein corona and towards the "lipid corona" may be the keystone of a better understanding and control of NP fate in human body.

Impact of elevated carbon dioxide and temperature on strawberry polyphenols

BACKGROUND

The strawberry cultivars 'Albion' and 'San Andreas' ('SA') were grown under various combinations of day temperature (25 and 30 °C) and carbon dioxide [CO₂ ] (400, 650 and 950 μmol mol^-1 ) conditions. The influence of different growth combinations on the polyphenol, flavonoid, anthocyanin, antioxidant, and individual phenolic compound content of fresh strawberry fruits was studied. The content of individual phenolic compounds of fresh strawberry fruits was quantified using high-performance liquid chromatography - ultraviolet (HPLC-UV).

RESULTS

Elevated [CO₂ ] and higher temperature caused significant increases in total polyphenol, flavonoid, anthocyanin and antioxidants in both strawberry cultivars when compared with plants grown under ambient conditions. Results of HPLC-UV analysis also revealed that individual phenolic compounds of fruits were also increased with increasing [CO₂ ] and temperature. However, the responses were significantly altered by the interaction of elevated [CO₂ ] and higher temperature. The individual and interaction effects of [CO₂ ] and temperature were also significantly cultivar dependent. The largest amounts of flavonoid (482 ± 68 mg kg^-1 FW) and antioxidant (19.0 ± 2.1 μmol g^-1 FW) were detected in 'Albion' grown at 30 °C and under 950 μmol mol^-1 , and total polyphenol (3350 ± 104 mg GAE kg^-1 FW) and anthocyanin (332 ± 16 mg kg^-1 FW) in 'San Andreas' grown at 25 °C and 950 μmol mol^-1 .

CONCLUSION

Strawberry fruit was rich with polyphenols and antioxidants when grown under elevated [CO₂ ] and higher temperature. There were also interactions between [CO₂ ] and temperature affecting the fruits' content. An increase in the polyphenol and antioxidant content in strawberry fruits would be highly beneficial to human health. © 2019 Society of Chemical Industry.

Enrichment procedure based on graphitized carbon black and liquid chromatography-high resolution mass spectrometry for elucidating sulfolipids composition of microalgae

Microalgae have recently become a popular functional food due to their health benefits. Sulfolipids, a class of substances abundant in this matrix, have been reported to have interesting bioactivities, such as anti-carcinogenic activity. However, despite the potential interest in sulfolipids, a dedicated analytical method for their characterization is currently lacking but would significantly increase the coverage of sulfolipids with respect to the direct lipidomic analysis. To achieve this goal, in this work a procedure, based on graphitized carbon black solid phase extraction, was developed for clean-up and enrichment of sulfolipids (sulfoquinovosyldiacylglycerols and sulfoquinovosylmonoacylglycerols) and it was applied to spirulina (Arthrospira platensis) microalgae. A careful study of the solid phase extraction conditions was performed, first to maximize the recovery of reference standards, then to increase the total number of identified sulfolipids from the spirulina lipid extract. All samples were analysed by ultra-high performance liquid chromatography coupled to high resolution mass spectrometry and lipids were tentatively identified by Lipostar, for a reliable lipid structure assignment. The developed method was compared to the direct lipidomic analysis without enrichment, to establish the enrichment efficiency in terms of number of identifications. From the comparison, the enrichment procedure proved better and allowed the tentative identification of 199 sulfolipids, which is the largest number reported so far for the Arthrospira platensis species. The described method was validated in terms of precision, accuracy, recovery, limit of quantitation and detection for two sulfolipids. Finally, a relative lipid quantitation based on peak area was carried out on the microalgae sample, which indicated nine abundant sulfolipids as representing ca. 60% of sulfolipids in spirulina microalgae.

A Triple Quadrupole and a Hybrid Quadrupole Orbitrap Mass Spectrometer in Comparison for Polyphenol Quantitation

Liquid chromatography coupled to low-resolution mass spectrometry (LRMS) has historically been a popular approach for compound quantitation. Recently, high-resolution mass spectrometry (HRMS) technical developments led to the introduction of new approaches for quantitative analysis. Whereas the performances of HRMS have been largely assessed for qualitative purposes, there are still questions about its suitability for quantitative analysis. Several papers on LRMS and HRMS comparison have been published; however, none of them was applied to polyphenol quantitation. In this work, a comparison between HRMS, operated in data-dependent acquisition mode, and LRMS, operated in selected-reaction-monitoring mode, was performed for polyphenol quantitation in wine. The two techniques were evaluated in terms of sensitivity, linearity range, matrix effect, and precision, showing the better performances of HRMS. The suitability of HRMS for quantitation purposes as well as qualitative screening makes HRMS the new technique of choice for both targeted and untargeted analysis.

Integrated strategy for the extraction and profiling of bioactive metabolites from Passiflora mollissima seeds combining pressurized-liquid extraction and gas/liquid chromatography-high resolution mass spectrometry

An integrated analytical methodology based on pressurized-liquid extraction (PLE) in two steps, followed by in vitro assays and liquid chromatography/gas chromatography coupled to high-resolution mass spectrometry (HRMS), was developed and applied for the isolation and characterization of potential bioactive metabolites from Passiflora mollissima seeds. PLE was proposed in two sequential steps: 1) recovery of the lipidic fraction using nonpolar solvents, and 2) recovery of the phenolic fraction from the defatted seeds' residue using polar solvents. Cyclohexane was selected as the most suitable extraction solvent for the seeds defatting process (20 min, 100 °C and 100 bar). PLE optimization by response surface methodology was carried out to obtain phenolics-rich extracts with the highest antioxidant activity. Optimal extraction yield (6.58%), total phenolic content (29.99 mg g^-1), total flavonoids content (0.94 mg g^-1) and antioxidant activity (6.94 mM trolox g^-1 and EC₅₀ of 2.66 μg mL^-1) were obtained operating at 150 °C with EtOH (100%) as solvent. Untargeted and semi-targeted MS and MS/MS data-mining strategies were successfully implemented for the rapid and comprehensive profiling of the polar and lipidic PLE fractions analysed by UHPLC and GC, respectively, coupled to quadrupole time-of-flight mass spectrometry (q-TOF-MS/MS). Polyphenols-rich extracts from P. mollisima seeds were characterized for the first time applying this approach, showing a broad variety of flavonoids, genuine flavanols (e.g. (epi)fisetinidol) and abundant proanthocyanidins. This application can be considered a successful demonstration of the great potential of the proposed methodology to effectively obtain and characterize complex natural extracts with potential bioactivity, by making use of powerful integrated identification strategies to facilitate the challenging post-acquisition data processing of huge datasets generated by HRMS analysis.

Sensitive untargeted identification of short hydrophilic peptides by high performance liquid chromatography on porous graphitic carbon coupled to high resolution mass spectrometry

The combination of an efficient chromatographic separation with post-column addition of a supercharging agent was evaluated for the determination of small peptides. The procedure takes advantage of porous graphitic carbon (PGC) ability in retaining very polar and ionic molecules to overstep the poor retention of small peptides on conventional reversed phase (RP) columns. The method was developed specifically for the most hydrophilic di-, tri- and tetrapeptides, which are not identified in ordinary peptidomics experiments. In addition to retention mechanisms acting on conventional RP, the method exploited the charge induced interactions generated by the charges on the peptides with the polarizable surface of PGC. This results in efficient retention of very short and highly polar peptides using classical RP mobile phases. The effects of varying mobile phase composition (organic solvent and ion-pairing additives) as well as column temperature have been thoroughly investigated using short peptide standards. Under optimized conditions (water and acetonitrile/tetrahydrofuran 99:1 (v/v), both with 0.15% trifluoroacetic acid, as phase A and B, respectively, 0.5 mL min^-1 flowrate at 50 °C) the effect of post-column addition of 3-nitrobenzylic alcohol was also investigated allowing effective coupling of the chromatographic system with high resolution mass spectrometry. Finally, an untargeted approach for peptide identification was pursued, based on precursor identification in database with all possible combinations of the 20 natural amino acids and fragmentation spectra matching to in silico generated spectra. The method was then applied to investigation of the short endogenous peptides in human serum from healthy individuals resulting in the identification of 30 short peptides.

Liquid Chromatographic Strategies for Separation of Bioactive Compounds in Food Matrices

Nowadays, there is an increasing attention for nutraceuticals and, in general, bioactive compounds naturally present in food. Indeed, the possibility of preserving human health and preventing disease (e.g., cardiovascular diseases, cancer etc.) by the intake of healthy food is attractive for both consumers and food industries. In turn, research in this field was also prompted significantly, with the aim of characterizing these bioactive compounds and ascribe to them a specific activity. The bioactive compounds can belong to several chemical classes. However, their chemical diversity and presence in complex matrices, such as food, make it challenging both their isolation and characterization. To tackle this issue, efficient separation systems are needed, which are mainly based on chromatography. In this context, this mini-review aims to provide the reader with an overview of the most relevant and recent approaches for the separation of the most common bioactive compounds in food, in particular polyphenols, phenols, carotenoids, and peptides, by liquid chromatography approaches.

Characterization of polyphenols in Australian sweet lupin (Lupinus angustifolius) seed coat by HPLC-DAD-ESI-MS/MS

Seeds of the legume lupin (Lupinus spp.) are becoming increasingly important as human food. The seed coat, at ~25% of the whole seed of Lupinus angustifolius (Australian sweet lupin, ASL), is the main by-product of lupin kernel flour production. The primary market for lupin seed coat is low value feed with very limited use in foods. In this study, seed coats of six ASL commercial varieties from two growing sites were sampled for identification and quantification of polyphenols using a high-performance liquid chromatography (HPLC) with diode array detector (DAD) and coupled with a triple quadrupole mass spectrometer which equipped with electrospray ionization source (ESI-MS/MS). Three flavones (apigenin-7-O-β-apiofuranosyl-6,8-di-C-β-glucopyranoside, vicenin 2, and apigenin-7-O-β-glucopyranoside), one isoflavone (genistein) and one dihydroflavonol derivative (aromadendrin-6-C-β-d-glucopyranosyl-7-O-[β-D-apiofuranosyl-(1 → 2)]-O-β-D-glucopyranoside), and several hydroxybenzoic and hydroxycinnamic acid derivatives were identified. Considerable variations in levels of individual polyphenols were found but apigenin-7-O-β-apiofuranosyl-6,8-di-C-β-glucopyranoside was the predominant polyphenol in all samples accounting for 73.08-82.89% of the total free polyphenols. These results suggest that ASL seed coat could be valuable dietary source of polyphenols.

Strategy for Screening of Antioxidant Compounds from Two Ulmaceae Species Based on Liquid Chromatography-Mass Spectrometry

Liquid chromatography-mass spectrometry (LC-MS)-based untargeted metabolomics implies that annotated metabolites can serve as potential markers of the associated bioactivities of plant extracts. Firstly, we selected Aphananthe aspera and Zelkova serrata (Family: Ulmaceae) from 16 Korean plant species based on their distinct principal component analysis (PCA) patterns in LC-MS datasets and antioxidant activity assays. Further, we chose 40% solid-phase extraction (SPE) extracts of the two species displaying the highest antioxidant activities coupled with distinct PCA patterns. Examining the metabolite compositions of the 40% SPE extracts, we observed relatively higher abundances of quercetin, kaempferol, and isorhamnetin O-glucosides for A. aspera, whereas quercetin, isorhamnetin O-glucuronides, and procyanidin dimer were relatively higher in Z. serrata. These metabolites were clearly distinguished in pathway map and displayed strong positive correlations with antioxidant activity. Further, we performed preparative high-performance liquid chromatography (prep-HPLC) analysis coupled with the 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) assay to validate their functional correlations. As a result, quercetin O-sophoroside was determined as the main antioxidant in A. aspera, while isorhamnetin O-glucuronide and procyanidin dimer were the primary antioxidants in Z. serrata. The current study suggests that the LC-MS-based untargeted metabolomics strategy can be used to illuminate subtle metabolic disparities as well as compounds associated with bioactivities.

Rapid Screening of Ellagitannins in Natural Sources via Targeted Reporter Ion Triggered Tandem Mass Spectrometry

Complex biomolecules present in their natural sources have been difficult to analyze using traditional analytical approaches. Ultrahigh-performance liquid chromatography (UHPLC-MS/MS) methods have the potential to enhance the discovery of a less well characterized and challenging class of biomolecules in plants, the ellagitannins. We present an approach that allows for the screening of ellagitannins by employing higher energy collision dissociation (HCD) to generate reporter ions for classification and collision-induced dissociation (CID) to generate unique fragmentation spectra for isomeric variants of previously unreported species. Ellagitannin anions efficiently form three characteristic reporter ions after HCD fragmentation that allows for the classification of unknown precursors that we call targeted reporter ion triggering (TRT). We demonstrate how a tandem HCD-CID experiment might be used to screen natural sources using UHPLC-MS/MS by application of 22 method conditions from which an optimized data-dependent acquisition (DDA) emerged. The method was verified not to yield false-positive results in complex plant matrices. We were able to identify 154 non-isomeric ellagitannins from strawberry leaves, which is 17 times higher than previously reported in the same matrix. The systematic inclusion of CID spectra for isomers of each species classified as an ellagitannin has never been possible before the development of this approach.

A two-step ultra-high-performance liquid chromatography-quadrupole/time of flight mass spectrometry with mass defect filtering method for rapid identification of analogues from known components of different chemical structure types in Fructus Gardeniae-Fructus Forsythiae herb pair extract and in rat's blood

Fructus Gardeniae-Fructus Forsythiae herb pair is an herbal formula used extensively to treat inflammation and fever, but few systematic identification studies of the bioactive components have been reported. Herein, the unknown analogues in the first-step screening were rapidly identified from representative compounds in different structure types (geniposide as iridoid type, crocetin as crocetin type, jasminoside B as monocyclic monoterpene type, oleanolic acid as saponin type, 3-caffeoylquinic acid as organic acid type, forsythoside A as phenylethanoid type, phillyrin as lignan type and quercetin 3-rutinoside as flavonoid type) by UPLC-Q-Tof/MS combined with mass defect filtering (MDF), and further confirmed with reference standards and published literatures. Similarly, in the second step, other unknown components were rapidly discovered from the compounds identified in the first step by MDF. Using the two-step screening method, a total of 58 components were characterized in Fructus Gardeniae-Fructus Forsythiae (FG-FF) decoction. In rat's blood, 36 compounds in extract and 16 metabolites were unambiguously or tentatively identified. Besides, we found the principal metabolites were glucuronide conjugates, with the glucuronide conjugates of caffeic acid, quercetin and kaempferol confirmed as caffeic acid 3-glucuronide, quercetin 3-glucuronide and kaempferol 3-glucuronide by reference standards, respectively. Additionally, most of them bound more strongly to human serum albumin than their respective prototypes, predicted by Molecular Docking and Simulation, indicating that they had lower blood clearance in vivo and possibly more contribution to pharmacological effects. This study developed a novel two-step screening method in addressing how to comprehensively screen components in herbal medicine by UPLC-Q-Tof/MS with MDF.

Fast analysis of polyphenols and alkaloids in cocoa-based products by ultra-high performance liquid chromatography and Orbitrap high resolution mass spectrometry (UHPLC-Q-Orbitrap-MS/MS)

The cocoa varieties Criollo, Forastero and Trinitario, which have different organoleptic properties, quite often are mixed together in cocoa-based products. The objective of this work was to develop a rapid method for the simultaneous determination of polyphenols (n = 35) and alkaloids (n = 2) in cocoa-based products by using the high throughput advantages provided by the Q Exactive Hybrid Quadrupole-Orbitrap Mass Spectrometer (HRMS). The proposed procedure was optimized and validated in terms of selectivity and specificity (mass accuracy <5 ppm), sensitivity (instrumental limit of detection from 15 to 30 fg), linearity (r² > 0.990), accuracy (recovery range from 89.1 to 112.4%) and precision (relative standard deviation <10%). The method was applied to 80 cocoa-based samples. Alkaloids represented on average the 57.7% of assayed compounds. Flavanols and procyanidins were the most abundant polyphenols being quantified in a range between 261 and 668 mg/kg and from 127 to 405 mg/g, respectively. Mass equivalents but structural isomers bioflavonoids were characterized by using the HRMS-Orbitrap methodology here developed.

Liquid chromatography-high resolution mass spectrometry for the analysis of phytochemicals in vegetal-derived food and beverages

The recent years witnessed a change in the perception of nutrition. Diet does not only provide nutrients to meet the metabolic requirements of the body, but it also constitutes an active way for the consumption of compounds beneficial for human health. Fruit and vegetables are an excellent source of such compounds, thus the growing interest in characterizing phytochemical sources, structures and activities. Given the interest for phytochemicals in food, the development of advanced and suitable analytical techniques for their identification is fundamental for the advancement of food research. In this review, the state of the art of phytochemical research in food plants is described, starting from sample preparation, throughout extract clean-up and compound separation techniques, to the final analysis, considering both qualitative and quantitative investigations. In this regard, from an analytical point of view, fruit and vegetable extracts are complex matrices, which greatly benefit from the use of modern hyphenated techniques, in particular from the combination of high performance liquid chromatography separation and high resolution mass spectrometry, powerful tools which are being increasingly used in the recent years. Therefore, selected applications to real samples are presented and discussed, in particular for the analysis of phenols, polyphenols and phenolic acids. Finally, some hot points are discussed, such as waste characterization for high value-compounds recovery and the untargeted metabolomics approach.