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The huge interest in the health-related properties of foods to improve health has brought about the development of sensitive analytical methods for the characterization of natural products with functional ingredients. Greek olive leaves and drupes constitute a valuable source of biophenols with functional properties. A novel ultra-high-performance...
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... quantification results in leaf samples of oleuropein, tyrosol and hydroxytyrosol (expressed in mg/Kg) are presented in Table 4. The chemical structures of oleuropein, tyrosol and hydroxytyrosol are illustrated in Figure 2. The concentration of oleuropein in the leaves ranged between below the LOQ (Agouromanakolia from Arcadia-Kynouria) and 293 mg/Kg (Agrilia from Laconia-Sparti). ...
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Five olive cultivars (Amfisis, Chalkidikis, Kalamon, Agrielia and Lefkolia Serron) grown in central Greece at different altitudes were studied on total phenolic content, phenolic fractions and the antioxidant activity DPPH. The olive cultivars Agrielia and Amfisis grown to an altitude of 500m are characterized by an highest TP content (13.32 and 6....
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... Compounds that appeared unique to leaves included hydroxylated forms of elenoic acid, licodione, naringenin, 4-hydroxybenzoic acid, and taxifolin. With regards to the preparation method impact on phenolics level, most phenolic and other active compounds in Agrilia leaves variety increased by extending infusion time from 3 to 10 min as exemplified by ca. 2 fold higher levels of oleuropein and hydroxytyrosol (Kritikou, Kalogiouri, Kolyvira, & Thomaidis, 2020). Likewise, the seasonal effect on leaf metabolome was assessed in Egyptian olive leaves collected during autumn (fruiting season) and spring (flowering season) from 12 cvs. ...
... In order to investigate which metabolites are affected by the pathogen, geraniol, and/or their combination, 5 samples of 200 mg of cucumber leaf tissue from each treatment (cucumber control, B. cinerea control, geraniol control, and B. cinerea + geraniol) were immediately homogenized in liquid nitrogen and stored at −80 • C for metabolite analysis. Frozen samples were transferred in 2-mL screw cap tubes, and 1 mL of MeOH:water (80:20, v/v) was added to extract the bioactive compounds from the plant matrix [70]. Then, the mixture was vortexed for 1 min. ...
... Target and suspect screening workflows were applied for the determination of metabolites in the samples, according to Kritikou et al. [70]. In target screening, the identification was carried out using standard solutions for confirmation. ...
In the present study, the bioactive substance geraniol was tested in vitro and in planta against B. cinerea on cucumber plants, and the changes in the metabolic profile of cucumber plants inoculated with the pathogen and/or treated with geraniol were monitored by a novel LC-QTOF-MS method employing target and suspect screening. The aforementioned treatments were also studied for their impact on membrane lipid peroxidation calculated as malondialdehyde (MDA) content. Additionally, geraniol-loaded nanoemulsions (GNEs) were synthesized and tested against B. cinerea as an integrated formulation mode of geraniol application. The EC50 values calculated for geraniol and GNEs against B. cinerea were calculated at 235 μg/mL and 105 μg/mL, respectively. The in planta experiment on cucumber plants demonstrated the ability of geraniol and GNEs to significantly inhibit B. cinerea under greenhouse conditions. The LC-QTOF-MS analysis of the metabolic profile of the cucumber plants treated with geraniol demonstrated an increase in the concentration levels of myricetin, chlorogenic acid, and kaempferol rhamnoside, as compared to control plants and the presence of B. cinerea caused an increase in sinapic acid and genistein. These compounds are part of important biosynthetic pathways mostly related to responses against a pathogen attack.
... However, the literature on the simultaneous determination of known and unknown bioactive constituents in the produced extracts still remains scarce. This gap could be fulfilled with the application of high resolution mass spectrometry (HRMS) which has already proved its excellent performance allowing the analysis of a wide range of naturally occurring constituents through target and non-target screening strategies [22,25]. ...
Extraction of polyphenolic compounds from lemon peels using deep eutectic solvents (DES) was investigated. A choline chloride-based DES paired with glycerol was used as the extraction solvent, alternative to conventional ones. Response surface methodology (RSM) was employed to optimize the extraction parameters, namely, the water concentration (CW), the liquid to solid ratio (RL/S) and the duration of the extraction (t) in terms of total phenol content and radical scavenging activity; the conditions that can be recommended as optimum for the recovery of the phenolic compounds were 55% (w/v), 13 mL g⁻¹ and 36 min, respectively. The composition of the obtained extracts under optimum conditions was compared with extracts prepared in ethanol and water. A novel reversed phase ultra-pressure electrospray liquid chromatographic time-of-flight mass spectrometric method (RP-UPLC–ESI–QTOF-MS) was developed and validated for the determination of individual bioactive compounds in the extracts through target, suspect, and non-target screening. The developed RP-UPLC–ESI–QTOF-MS methodology was validated and presented adequately low limits of detection (LODs) and limits of quantification (LOQs) over the ranges 8.64 (quercetin)–30.4 μg L⁻¹ (p-coumaric acid), and 25.9 (quercetin)–91.2 μg L⁻¹ (p-coumaric acid), respectively. The RSD% of the within-day and between-day assays were lower than 3.2, and 9.8, respectively, demonstrating good method precision. Overall, 10 compounds were determined and quantified through target screening, as well as 4 suspect, and 9 non-target compounds were tentatively identified in the extracts by means of suspect and non-target screening, respectively.
... Based on the above, encapsulation of anthocyanins from Cornelian cherry extracts could boost their use as natural food colorants. To evaluate the efficiency of this process, high-resolution mass spectrometry (HRMS) could be used for the characterizations of plant-based extracts increasing the breadth of traditional targeted analysis and providing screening and tentative identification for both target and non-target compounds [17]. The use of time-of-flight mass spectrometers supplied with ionization detectors enable the identification of unknown analytes with high accuracy and could be effectively applied in the analysis and characterization of natural constituents in plant matrices. ...
The objective of this study was the production of green extracts from Cornelian cherry pomace and the valorization of their anthocyanin content for their potential use as food colorants. Aqueous solutions of β-cyclodextrin were used both as green extraction solvents as well as means of anthocyanins’ stabilization. The extracts were analyzed by a novel liquid chromatographic method coupled to triple quadrupole time-of-flight mass spectrometry analytical methodology (LC-QTOF-MS) to assess their anthocyanin content. FTIR spectroscopy was used to investigate possible interactions between cyclodextrin and Cornelian cherry’s anthocyanins. The stability of anthocyanins was evaluated under different pH conditions and in the presence of metal ion Fe⁺². The extracts were finally evaluated as colorants in two different food systems. The results showed that the color of β-cyclodextrin extract was preserved through storage. Additionally, the combination of β-cyclodextrin extraction and storage at low temperature contributes to the development of a stable acidic non-carbonated red beverage.
... Secoiridoids (40) made up the most numerous group of compounds, followed by flavonoids (10), pentacyclic triterpenes (5), simple phenols or related analytes (3) and organic acids (2). It should be noted that a large part of the identified compounds corresponded to glycosylated derivatives and isomers, especially in the case of secoiridoids. ...
... Three other substances, which were found in the profiles with high relative intensities, could not be identified with confidence. The peak with m/z 537.1605 (C 25 H 30 O 13 ) was tentatively assigned to fraxamoside, considering that its presence has been recently described in Greek olives by Kritikou and co-authors [40]. The MS/MS analysis described in their work agreed with some of our in-source fragments (m/z 323.0811 and 221.0273), which suggests that it could be the same compound they described. ...
Olea europaea subsp. cuspidata has a relatively low commercial value due to the low size and pulp to stone ratio of its drupes compared to commercial olive cultivars. Nevertheless, this subspecies could represent a valid source of useful traits for olive breeding. In the current work, the drupe metabolic composition (secoiridoids, flavonoids, simple phenols, triterpenic acids, etc.) of a progeny of 27 cuspidata genotypes coming from free pollination and their female parent was evaluated by applying a powerful LC-MS method. A total of 62 compounds were detected within the profiles; 60 of them were annotated and 27 quantified. From a quantitative point of view, the genotypes from the progeny of cuspidata showed quite different metabolic profiles to olive common cultivars ("Arbequina", "Frantoio", "Koroneiki" and "Picual") used as controls. Cuspidata drupes were richer in terms of several bioactive compounds such as rutin, hydroxytyrosol glucoside, a few interesting secoiridoids and the compounds of m/z 421 and 363. The relationships among several secondary metabolites determined in the progeny inferred from the results of both PCA and cross-correlation analysis were explained according to metabolic biosynthesis pathways in olive drupes. These outcomes underlined the potential of cuspidata genetic resources as a source of potentially interesting variability in olive breeding programs.
... A suspect list was generated from the literature consisting of 60 significant bioactive compounds that have been identified in olive leaves, drupes, other organs of Olea europaea L. and olive oil to investigate their presence in the samples. According to the authors by means RP-UHPLC-qToF-MS/MS the application of the target screening workflow resulted in the identification of 10 phenols in leaves and 7 in drupes, while other 36 suspect compounds were identified in leaves and 33 in drupes with suspect screening (Kritikou et al., 2020). Having said that there is no single method that can reach this goal, the traditional quality control of NCPs is based on the monitoring of arbitrarily chosen "marker" compounds, which can also be "active compounds," if a specific pharmacological activity was described. ...
Metabolomics is an area of intriguing and growing interest. Since the late 1990s, when the first Omic applications appeared to study metabolite’s pool ("metabolome"), to understand new aspects of the global regulation of cellular metabolism in biology, there have been many evolutions. Currently, there are many applications in different fields such as clinical, medical, agricultural and food. In our opinion, it is clear that developments in metabolomics analysis have also been driven by advances in mass spectrometry (MS) technology. As natural complex products (NCPs) are increasingly used around the world as medicines, food supplements, and substance‐based medical devices, their analysis using metabolomic approaches will help to bring more and more rigor to scientific studies and industrial production monitoring. This review is intended to emphasize the importance of metabolomics as a powerful tool for studying NCPs, by which significant advantages can be obtained in terms of elucidation of their composition, biological effects and quality control. The different approaches of metabolomic analysis, the main and basic techniques of multivariate statistical analysis are also briefly illustrated, in order to allow an overview of the workflow associated with the metabolomic studies of NCPs. Therefore, various articles and reviews are illustrated and commented as examples of the application of MS‐based metabolomics to NCPs. This article is protected by copyright. All rights reserved.
... A statistically significant difference was observed for the concentration of rutin among the septa of the different varieties (p = 0.002). Rutin possesses promising antioxidant potential and exhibits significant biological properties, thus, playing an essential role in the human body's numerous physiological functions [26]. According to the literature, rutin may provide a wide variety of therapeutic effects, such as antiallergic, antiviral, antihypertensive, vasoactive, cytoprotective, anti-inflammatory, antiprotozoal, hypolipidemic, antispasmodic, anticarcinogenic, antibacterial, and antiplatelet activities [27]. ...
Walnut byproducts have been shown to exert functional properties, but the literature on their bioactive content is still scarce. Among walnut byproducts, walnut septum is a dry ligneous diaphragm tissue that divides the two halves of the kernel, exhibiting nutritional and medicinal properties. These functional properties are owing to its flavonoid content, and in order to explore the flavonoid fraction, an ultrasound-assisted (UAE) protocol was combined with solid phase extraction (SPE) and coupled to high-performance liquid chromatography with diode array detection (HPLC-DAD) for the determination of flavonoids in Greek walnut septa membranes belonging to Chandler, Vina, and Franquette varieties. The proposed UAE-SPE-HPLC-DAD method was validated and the relative standard deviations (RSD%) of the within-day and between-day assays were lower than 6.2 and 8.5, respectively, showing good precision, and high accuracy ranging from 90.8 (apigenin) to 97.5% (catechin) for within-day assay, and from 88.5 (myricetin) to 96.2% (catechin) for between-day assay. Overall, seven flavonoids were determined (catechin, rutin, myricetin, luteolin, quercetin, apigenin, and kaempferol) suggesting that the walnut septum is a rich source of bioactive constituents. The quantification results were further processed using ANOVA analysis to examine if there are statistically significant differences between the concentration of each flavonoid and the variety of the walnut septum.
... The mass accuracy of the precursor and qualifier ions was lower than 2.5 mDa, compared to the standard solutions, and the isotopic fit was lower than 100 mSigma in all cases. The fragments were verified on the basis of MS/MS records in the literature [24,26]. The target screening results are presented in Table 1. ...
... The suspect identification workflow incorporated strict filtering steps, interpretation of the MS/MS spectra and t R prediction, as rpeviosly described by Kalogiouri et al. [26,50]. The MS/MS fragments were interpreted using Metfrag and compared with the fragments and the experimental t R s reported in previous works of our group [24,26,50]. ...
Extra virgin olive oil (EVOO) is recognized for its nutritional virtues and the beneficial health effects deriving from its hydrophilic fraction (phenolic acids, phenolic alcohols, flavonoids, and secoiridoids). The phenolic compounds of EVOOs possess multiple biological properties such as antioxidant, antimicrobial, anticarcinogenic, and anti-inflammatory properties, among others. Considering that EVOOs produced in Greece are recognized as high-quality products due to their rich phenolic content, it is imperative to characterize Greek monovarietal EVOOs and ensure that their uniqueness is closely linked to their botanical and territorial origin. In this work, an ultra-high-performance liquid chromatography–quadrupole time-of-flight tandem mass spectrometry (UHPLC-QTOF-MS) analytical method combined with target and suspect screening was used to characterize monovarietal EVOOs of the Kolovi variety from Lesvos, and thereby establish their phenolic fingerprint. Overall, 25 phenols were determined, and the total quantification and semi-quantification results ranged between 251 and 1230 mg/kg, highlighting the high phenolic content of the Kolovi variety from the island of Lesvos in the North Aegean.
... Less is known about the minor phenolic fraction [8,23]. Phenolic constituents are secondary plant metabolites subjected to environmental modifications [8,24]. The analysis and evaluation of the phenolic profile of agricultural products provides valuable information about the quality characteristics among the plant species, and this is why the phenolic profile is investigated in authenticity studies [25]. ...
A high-pressure liquid chromatographic method coupled to diode array detector (HPLC-DAD) was developed for the determination of phenolic compounds that could be used as markers in authentication studies of walnuts belonging to the Chandler variety, originating from Bulgaria, Greece, and France. An ultrasound-assisted extraction (UAE) protocol applied in the extraction of phenolic compounds was optimized. The method was validated and the relative standard deviations (RSD%) of the within-day, and between-day assays was lower than 6.3 and 11.1, respectively, showing adequate precision, and good accuracy ranging from 86.4 (sinapic acid) to 98.4% (caffeic acid) for within-day assay, and from 90.1 (gallocatechin gallate) to 100.6% (gallic acid) for between-day assay. Eighteen phenolic compounds were determined belonging to the classes of phenolic acids and flavonoids. The quantification results were further processed with chemometrics, and a robust partial least square–discriminant analysis (PLS-DA) model was developed for the classification of the samples according to their geographical origin, proposing markers that could be used for the control of walnuts authenticity and the detection of fraudulent incidents.
... For the extraction of the phenolic compounds, a modified extraction protocol was applied, as previously suggested by Kritikou et al. [39]. In brief, 0.5 g of each homogenized sample was weighted in 2 mL Eppendorf tubes and 1 mL of MeoH: H 2 O (80:20, v/v) was added. ...
Reversed phase-high-pressure liquid chromatographic methodologies equipped with UV detector (RP-HPLC-UV) were developed for the determination of phenolic compounds and tocopherols in almonds. Nineteen samples of Texas almonds originating from USA and Greece were analyzed and 7 phenolic acids, 7 flavonoids, and tocopherols (−α, −β + γ) were determined. The analytical methodologies were validated and presented excellent linearity (r2 > 0.99), high recoveries over the range between 83.1 (syringic acid) to 95.5% (ferulic acid) for within-day assay (n = 6), and between 90.2 (diosmin) to 103.4% (rosmarinic acid) for between-day assay (n = 3 × 3), for phenolic compounds, and between 95.1 and 100.4% for within-day assay (n = 6), and between 93.2–96.2% for between-day assay (n = 3 × 3) for tocopherols. The analytes were further quantified, and the results were analyzed by principal component analysis (PCA), and agglomerative hierarchical clustering (AHC) to investigate potential differences between the bioactive content of almonds and the geographical origin. A decision tree (DT) was developed for the prediction of the geographical origin of almonds proposing a characteristic marker with a concentration threshold, proving to be a promising and reliable tool for the guarantee of the authenticity of the almonds.
