Edible Insects an Alternative Nutritional Source of Bioactive Compounds: A Review

Edible insects have the potential to become one of the major future foods. In fact, they can be considered cheap, highly nutritious, and healthy food sources. International agencies, such as the Food and Agriculture Organization (FAO), have focused their attention on the consumption of edible insects, in particular, regarding their nutritional value and possible biological, toxicological, and allergenic risks, wishing the development of analytical methods to verify the authenticity, quality, and safety of insect-based products. Edible insects are rich in proteins, fats, fiber, vitamins, and minerals but also seem to contain large amounts of polyphenols able to have a key role in specific bioactivities. Therefore, this review is an overview of the potential of edible insects as a source of bioactive compounds, such as polyphenols, that can be a function of diet but also related to insect chemical defense. Currently, insect phenolic compounds have mostly been assayed for their antioxidant bioactivity; however, they also exert other activities, such as anti-inflammatory and anticancer activity, antityrosinase, antigenotoxic, and pancreatic lipase inhibitory activities.

Determination of trace levels of organic fining agents in wines: Latest and relevant findings

The production of red wine plays a key role in the local and international economies of several nations. During the winemaking process, to clarify the final product, before bottling, and to remove undesired substances (proteins, phenols, and tannins), fining agents are commonly added to wines. These substances have different origins (animal and vegetable proteins or mineral compounds), and they show a potential risk for the health of allergic subjects. For these reasons, the residues of fining agents, constituted by exogenous proteins based on gluten, egg, and milk proteins, should not be present in the final product and their trace residues should be quantified with accuracy. In the last decade, several analytical approaches have been developed for their quantitative determination using different sample treatment protocols and analytical techniques. These methods are based on liquid chromatography coupled with mass spectrometry or enzyme-linked immunosorbent assays (ELISAs). Recently, biosensors have been proposed as a potential alternative to immunoassay approaches, allowing rapid, cheap, and simple multi-residue detection. This short review aimed to report the most recent and relevant findings in the field.

Hydroxytyrosol-Fortified Foods Obtained by Supercritical Fluid Extraction of Olive Oil

A new original process has been set-up to obtain hydroxytyrosol-enriched food by means of CO₂ supercritical fluid extraction. The process is based on the direct adsorption of hydroxytyrosol on selected foodstuff (e.g., flour, whole-wheat flour, and sugar) when placed in contact with olive oil (which is known to contain this phenol) under controlled temperature and pressure conditions of supercritical CO₂. The transfer of the nutraceutical to the foodstuff was initially evaluated using a fortified olive oil model and was then applied to commercial olive oil and foodstuff. The yield of the hydroxytyrosol transfer was demonstrated to be quantitative. In order to prove the suitability of the final products, hydroxytyrosol-enriched flour was used to prepare a bread roll, which maintained the nutraceutical characteristics after the cooking. Finally, DPPH based experiments were performed to prove the radical scavenging activity of the functionalized foodstuff.

High-throughput determination of flavanone-O-glycosides in citrus beverages by paper spray tandem mass spectrometry

A fast and accurate methodology for the quantification of the most abundant flavanone glycosides in citrus beverages has been developed. The approach relies on the use of paper spray mass spectrometry, which allows to record data in few minutes and without sample pre-treatment. The experiments have been carried out in Multiple Reaction Monitoring scan mode, in order to obtain the best specificity and sensitivity. The analytical parameters were all satisfactory. The results coming from the analysis of real samples were compared to the data obtained by the commonly used chromatographic method, proving the robustness of the proposed approach.

Paper spray tandem mass spectrometry: A rapid approach for the assay of parabens in cosmetics and drugs

A fast methodology for the assay of parabens in drug and cosmetic preparations has been presented. The procedure developed is based on paper spray tandem mass spectrometry and isotope dilution approach. For each investigated paraben, the corresponding labeled standard has been used in order to improve the accuracy and reproducibility of the analyses. The MS experiments have been performed under MRM conditions, monitoring the transitions [M-H]^- → m/z 92 and [M-H]^- → m/z 98, respectively, for each analyte and the corresponding labeled internal standard. The quantitative assay has been performed using a calibration curve built from 2 to 15 mg/L. The method accuracy, in all case near 100%, was evaluated using fortified samples at two concentration levels, which are representative of the lower and the higher portion of calibration curve. The good values of LOQ, LOD, and reproducibility confirm the consistency of the developed approach.

Protein Extraction, Enrichment and MALDI MS and MS/MS Analysis from Bitter Orange Leaves (Citrus aurantium)

Citrus aurantium is a widespread tree in the Mediterranean area, and it is mainly used as rootstock for other citrus. In the present study, a vacuum infiltration centrifugation procedure, followed by solid phase extraction matrix-assisted laser desorption ionization tandem mass spectrometry (SPE MALDI MS/MS) analysis, was adopted to isolate proteins from leaves. The results of mass spectrometry (MS) profiling, combined with the top-down proteomics approach, allowed the identification of 78 proteins. The bioinformatic databases TargetP, SignalP, ChloroP, WallProtDB, and mGOASVM-Loc were used to predict the subcellular localization of the identified proteins. Among 78 identified proteins, 20 were targeted as secretory pathway proteins and 36 were predicted to be in cellular compartments including cytoplasm, nucleus, and cell membrane. The largest subcellular fraction was the secretory pathway, accounting for 25% of total proteins. Gene Ontology (GO) of Citrus sinensis was used to simplify the functional annotation of the proteins that were identified in the leaves. The Kyoto Encyclopedia of Genes and Genomes (KEGG) showed the enrichment of metabolic pathways including glutathione metabolism and biosynthesis of secondary metabolites, suggesting that the response to a range of environmental factors is the key processes in citrus leaves. Finally, the Lipase GDSL domain-containing protein GDSL esterase/lipase, which is involved in plant development and defense response, was for the first time identified and characterized in Citrus aurantium.

2,3-Diaminopropanols Obtained from d-Serine as Intermediates in the Synthesis of Protected 2,3-l-Diaminopropanoic Acid (l-Dap) Methyl Esters

A synthetic strategy for the preparation of two orthogonally protected methyl esters of the non-proteinogenic amino acid 2,3-l-diaminopropanoic acid (l-Dap) was developed. In these structures, the base-labile protecting group 9-fluorenylmethyloxycarbonyl (Fmoc) was paired to the p-toluensulfonyl (tosyl, Ts) or acid-labile tert-butyloxycarbonyl (Boc) moieties. The synthetic approach to protected l-Dap methyl esters uses appropriately masked 2,3-diaminopropanols, which are obtained via reductive amination of an aldehyde prepared from the commercial amino acid N^α-Fmoc-O-tert-butyl-d-serine, used as the starting material. Reductive amination is carried out with primary amines and sulfonamides, and the process is assisted by the Lewis acid Ti(OⁱPr)₄. The required carboxyl group is installed by oxidizing the alcoholic function of 2,3-diaminopropanols bearing the tosyl or benzyl protecting group on the 3-NH₂ site. The procedure can easily be applied using the crude product obtained after each step, minimizing the need for chromatographic purifications. Chirality of the carbon atom of the starting d-serine template is preserved throughout all synthetic steps.

Molecular species fingerprinting and quantitative analysis of saffron (Crocus sativus L.) for quality control by MALDI mass spectrometry

Herein we describe a rapid, simple, and reliable method for the quantitative analysis and molecular species fingerprinting of saffron (Crocus sativus L.) by direct MS and MS/MS analysis. Experimentally, powdered saffron was subjected to a brief treatment with a 0.3% TFA water/acetonitrile solution, and the resulting mixture was directly placed on the MALDI plate for analysis. This approach allowed the detection of the commonly observed crocins C-1-C-6 and flavonols, together with the identification of the unknown highly glycosylated crocins C-7, C-8 and C-9, and carotenoid-derived metabolites. The strategy endorsed the simultaneous detection and characterization of saffron and adulterant markers using crude extracts of the adulterant itself and synthetic sets of adulterated authentic saffron samples. The implementation of the strategy was to measure the amount of an unknown adulterant from the crude extract using curcumin as a non-isotopic isobaric internal standard. The relationship between the saffron and curcumin molar ratios were established with a correlation coefficient of 0.9942. The ANOVA regression model was significant, F(1, 72) = 13 595.82, p < 0.001, y = (0.0116 ± 0.0001)x + (-0.1214 ± 0.0086). No matrix effects were observed and good results were obtained with respect to instrumental repeatability (*RSD% < 2%) and LOD (1.1%). The analysis of commercial samples of saffron using the proposed approach showed the suitability of the method for routine analysis (minimal sample preparation and very short measuring time per sample).

Tandem mass spectrometry: a convenient approach in the dosage of steviol glycosides in Stevia sweetened commercial food beverages

The use of sweeteners extracted from leaves of the plant species Stevia rebaudiana is increasing worldwide. They are recognized as generally recognized as safe by the US-FDA and approved by EU-European Food Safety Authority, with some recommendation on the daily dosage that should not interfere with glucose metabolism. The results presented here introduce an easy analytical approach for the identification and assay of Stevia sweeteners in commercially available soft drink, based on liquid chromatography coupled to tandem mass spectrometry, using a natural statin-like molecule, Brutieridin, as internal standard. Copyright © 2017 John Wiley & Sons, Ltd.

Rapid discrimination of bergamot essential oil by paper spray mass spectrometry and chemometric analysis

A novel approach for the rapid discrimination of bergamot essential oil from other citrus fruits oils is presented. The method was developed using paper spray mass spectrometry (PS-MS) allowing for a rapid molecular profiling coupled with a statistic tool for a precise and reliable discrimination between the bergamot complex matrix and other similar matrices, commonly used for its reconstitution. Ambient mass spectrometry possesses the ability to record mass spectra of ordinary samples, in their native environment, without sample preparation or pre-separation by creating ions outside the instrument. The present study reports a PS-MS method for the determination of oxygen heterocyclic compounds such as furocoumarins, psoralens and flavonoids present in the non-volatile fraction of citrus fruits essential oils followed by chemometric analysis. The volatile fraction of Bergamot is one of the most known and fashionable natural products, which found applications in flavoring industry as ingredient in beverages and flavored foodstuff. The development of the presented method employed bergamot, sweet orange, orange, cedar, grapefruit and mandarin essential oils. PS-MS measurements were carried out in full scan mode for a total run time of 2 min. The capability of PS-MS profiling to act as marker for the classification of bergamot essential oils was evaluated by using multivariate statistical analysis. Two pattern recognition techniques, linear discriminant analysis and soft independent modeling of class analogy, were applied to MS data. The cross-validation procedure has shown excellent results in terms of the prediction ability because both models have correctly classified all samples for each category. Copyright © 2016 John Wiley & Sons, Ltd.

A major allergen in rainbow trout (Oncorhynchus mykiss): complete sequences of parvalbumin by MALDI tandem mass spectrometry

Fish parvalbumin (PRVB) is an abundant and stable protein in fish meat. The variation in cross-reactivity among individuals is well known and explained by a broad repertoire of molecular forms and differences between IgE-binding epitopes in fish species. PVRB has "sequential" epitopes, which retain their IgE-binding capacity and allergenicity also after heating and digestion using proteolytic enzymes. From the allergonomics perspective, PRVB is still a challenging target due to its multiple isoforms present at different degrees of distribution. Little information is available in the databases about PVRBs from Oncorhynchus mykiss. At present, only two validated, incomplete isoforms of this species are included in the protein databases: parvalbumin beta 1 (P86431) and parvalbumin beta 2 (P86432). A simple and rapid protocol has been developed for selective solubilization of PRVB from the muscle of farmed rainbow trout (Oncorhynchus mykiss), followed by calcium depletion, proteolytic digestion, MALDI MS, and MS/MS analysis. With this strategy thermal allergen release was assessed and PRVB1 (P86431), PRVB1.1, PRVB2 (P86432) and PRVB2.1 variants from the rainbow trout were sequenced. The correct ordering of peptide sequences was aided by mapping the overlapping enzymatic digests. The deduced peptide sequences were arranged and the theoretical molecular masses (Mr) of the resulting sequences were calculated. Experimental masses (Mr) of each PRVB variant were measured by linear MALDI-TOF.

Electrospray ion mobility mass spectrometry of positively and negatively charged (1R,2S)-dodecyl(2-hydroxy-1-methyl-2-phenylethyl)dimethylammonium bromide aggregates

RATIONALE

Self-assembling processes of surfactants in the gas phase constitute a developing research field of interest since they allow information to be gained on the peculiar structural organization of these aggregates, on their ability to incorporate from small molecules up to proteins and on their possible use as carriers of drugs in the gas phase or as cleaning agents and exotic reaction media.

METHODS

The mass spectra of charged aggregates of the chiral surfactant (1R,2S)-dodecyl(2-hydroxy-1-methyl-2-phenylethyl)dimethylammonium bromide (DMEB) in the gas phase have been recorded using a Synapt G2-Si mass spectrometer in the positive and negative ion mode. For comparison purposes, the mass spectra of sodium bis(2-ethylhexyl)sulfosuccinate and sodium octane sulfonate aggregates have also been recorded under the same experimental conditions. The collisional cross sections of positively and negatively charged DMEB aggregates were obtained through an appropriate calibration of the measured drift times.

RESULTS

For all the surfactants investigated, it has been found that there is a lowest and a highest limit of the aggregation number at each charge state: no aggregates are found outside this range. Moreover, the occurrence at each aggregation number and extra charge of a unique value of drift time points toward aggregates whose conformations do not show discernible shape change in the experiment time scale. The analysis of the collisional cross sections emphasizes that the DMEB aggregates are nearly spherical clusters somewhat affected by the charge state and constituted by interlaced polar and apolar domains.

CONCLUSIONS

The analysis of all the experimental findings indicates that in the gas phase DMEB forms supramolecular aggregates characterized by an internal organization whose stability is triggered by the charge state. The comparison of the behavior of DMEB aggregates with that of sodium bis(2-ethylhexyl)sulfosuccinate and sodium octane sulfonate aggregates allows us to highlight the effects on the aggregate organization in gas phase due to nature of the head group and alkyl chain steric hindrance.

A major allergen in rainbow trout (Oncorhynchus mykiss): complete sequences of parvalbumin by MALDI tandem mass spectrometry

Fish parvalbumin (PRVB) is an abundant and stable protein in fish meat. The variation in cross-reactivity among individuals is well known and explained by a broad repertoire of molecular forms and differences between IgE-binding epitopes in fish species. PVRB has "sequential" epitopes, which retain their IgE-binding capacity and allergenicity also after heating and digestion using proteolytic enzymes. From the allergonomics perspective, PRVB is still a challenging target due to its multiple isoforms present at different degrees of distribution. Little information is available in the databases about PVRBs from Oncorhynchus mykiss. At present, only two validated, incomplete isoforms of this species are included in the protein databases: parvalbumin beta 1 (P86431) and parvalbumin beta 2 (P86432). A simple and rapid protocol has been developed for selective solubilization of PRVB from the muscle of farmed rainbow trout (Oncorhynchus mykiss), followed by calcium depletion, proteolytic digestion, MALDI MS, and MS/MS analysis. With this strategy thermal allergen release was assessed and PRVB1 (P86431), PRVB1.1, PRVB2 (P86432) and PRVB2.1 variants from the rainbow trout were sequenced. The correct ordering of peptide sequences was aided by mapping the overlapping enzymatic digests. The deduced peptide sequences were arranged and the theoretical molecular masses (Mr) of the resulting sequences were calculated. Experimental masses (Mr) of each PRVB variant were measured by linear MALDI-TOF.

Determination of ketosteroid hormones in meat by liquid chromatography tandem mass spectrometry and derivatization chemistry

A method for the determination and quantification of ketosteroid hormones in meat by mass spectrometry, based on the derivatization of the carbonyl moiety of steroids by O-methylhydroxylamine, is presented. The quantitative assay is performed by means of multiple-reaction-monitoring (MRM) scan mode and using the corresponding labelled species, obtained by reaction with d 3-methoxylamine, as internal standard. The accuracy of the method was established by evaluating artificially spiked samples, obtaining values in the range 90-110%. Recovery tests were performed on blank matrix samples spiked with non-natural steroids including trenbolone and melengestrol acetate. The latter experiment revealed that the yield of the extraction processes was approximately 60%. Good values of LOQ and LOD were achieved, making this method competitive with current hormone assay methods.

N-hydroxysuccinimidyl p-methoxybenzoate as suitable derivative reagent for isotopic dilution assay of biogenic amines in food

We present a simple methodology for the simultaneous identification and determination of biogenic amines in food matrices, based on the use of a stable isotope-coded derivatization and liquid chromatography tandem mass spectrometry. The tagging reagent is N-hydroxysuccinimidyl ester of d(0)/d(4) -4-methoxybenzoic acid (d(0)/d(4) -4-MBA-OSu) which mainly functionalizes primary amines. The identification and structural characterization of tagged biogenic amines were exploited by matrix-assisted laser desorption/ionization-mass spectrometry (MS) and MS/MS. Multiple-reaction monitoring has been applied in the assay of biogenic amines in different foodstuffs, providing a method whose reliability is confirmed by the values of accuracy (12%) and by the calculated analytical parameters.

Assessment of perioperative transfusion requirement for cirrhotic patients undergoing elective hepatectomy

BACKGROUND

The possibility of outlining a risk profile for perioperative blood transfusion of cirrhotic patients submitted to hepatic resection can help to rationalize transfusion policy.

METHODS

Data from 323 hepatic resections, performed in cirrhotic patients, were reviewed. Bootstrap and a leave-one-out logistic regressions were applied to test the accuracy of available risk scores for peri-operative transfusion identified from PubMed search of the last 20 years, to refine them, and to provide internal validation for present results.

RESULTS

One-hundred-six patients (32.8%) required blood transfusions during either intra- and/or postoperative. The predictive accuracy of three identified risk scores was poor with the area under receiver operating characteristics (AUROC) curves <0.70 in all cases. Tumor diameter, hemoglobin and presence of coronary artery disease were confirmed, in the present cohort, as predictors of blood transfusion together with serum albumin and bilirubin. The leave-one-out logistic regression results in an AUROC of 0.80, and of 0.79 for internal validation, significantly higher than that of the three scores tested (P<0.001). A Maximal Surgical Blood Order Schedule stratification was proposed.

CONCLUSION

The risk profile for transfusion of cirrhotic patients undergoing hepatectomy can be better assessed with a model that combines already known clinical factors and hepatic function indexes.

Structural characterisation of malonyl flavonols in leek (Allium porrum L.) using high-performance liquid chromatography and mass spectrometry

INTRODUCTION

Vegetables contain a variety of phytochemicals that have the ability to modify enzymatic and chemical reactions, and therefore may have a positive influence on human health. In particular kaempferol is known to possess anti-carcinogenic activity.

OBJECTIVE

The purpose of this work was to determine the structure of glycosylated kaempferol derivatives, acylated with malonic acid on the sugar portion.

METHODS

A methanolic extract of the leaves of Allium porrum L. was submitted to fractionation procedures through semi-preparative HPLC/UV-MS techniques. The collected fractions were evaluated by accurate tandem mass spectrometry experiments using an electrospray ionisation (ESI) quadrupole time-of-flight instrument. Isolated compounds were hydrolysed in order to obtain information on the ester moieties.

RESULTS

The structures of five compounds not previously reported in leek were determined. The molecules are mono-hexose, di-hexose and coumaroyl, feruloyl and caffeoyl acylated di-hexose derivatives of kaempferol. The common characteristic of the structures relies on the presence of the malonyl moiety on the primary alcoholic function of the sugar immediately linked to the aglycone. Accurate tandem MS experiments and basic hydrolysis treatments revealed a sequence of the acylated glycosidic moieties.

CONCLUSION

A set of secondary metabolites of the aerial part of Allium porrum L. (leek) was identified and characterised by ESI/MS(2) . Knowledge of the presence of these first-reported compounds in leek could provide the means for fully understanding of the metabolism of this plant in relation to the biosynthesis of the phenolics.

High-throughput determination of Sudan Azo-dyes within powdered chili pepper by paper spray mass spectrometry

A high-throughput mass spectrometric method is presented for the simultaneous detection of Sudan I, II, III, IV and Para-Red azo-dyes in foodstuff. The method is based on the use of paper spray mass spectrometry (MS) and deuterium-labeled internal standards on a triple-quadrupole instrument. A detailed assay of each azo-dye was performed by the isotope dilution method, through the precursor ion scan approach, using deuterium-labeled internal standards. The gas-phase breakdown pattern of each labeled and unlabeled analogue displays the naphthoic moiety as a common fragment. Sudan dyes can be determined above the threshold of 1 ppm. Paper spray allows for a wide range of analytes and samples to be investigated by MS in the open air and without sample preparation and bypassing chromatography.

The use of social networking to explore knowledge and attitudes toward organ donation in Italy

BACKGROUND

Currently, online social media have become increasingly popular and can provide the opportunity to provide and acquire information regarding knowledge and attitudes toward organ donation and transplantation. To evaluate participants' knowledge about organ donation, information sources and donation principles, an on-line survey was distributed through social network in Italy.

METHODS

10584 persons were invited to respond to the questionnaire, the response rate was 22.8% and a total of 2258 complete responses were analyzed.

RESULTS

The majority of participants were in favour of organ donation (94.9%), but this proportion decreased when asking for consent to donation of a family member's organs (75.2%; P<0.001). Internet represented a considerable proportion of information sources (37.2%), that were much less frequently represented by family doctors (5.6%) and school education (18.6%). Conversely, 68.5% of participants think that family doctors should provide information regarding donation and 81.9% think schools should also provide such education (P<0.001). A good knowledge about donation principles was the main factor associated with a positive attitude toward donation (P<0.001).

CONCLUSION

Efforts must be aimed at involving schools and family doctors in education about donation; the use of social networks can represent a way of improving such knowledge.

Light and heavy dansyl reporter groups in food chemistry: amino acid assay in beverages

5-Dimethylamino-1-sulfonyl naphthalene (DNS, commonly referred as dansyl) is a functionality, bearing well-established properties in directing the fragmentation, by mass spectrometry (MS), of the corresponding ionized sulfonylated derivatives. This property is shared also by its labeled analogs. The use of d(0)/d(6) DNS derivatives is now exploited in the application of the well-established isotope dilution mass spectrometric approach in the assay of complex mixtures. A new method for the quantitation of amino acids (AAs) in beverages is therefore presented, which relies on liquid chromatographic separation of their N-dansylated derivatives followed by comparative electrospray tandem MS/MS of the d(0)/d(6) isobaric mixtures. Labeled and unlabeled DNS derivatives of the selected AAs are readily available by microwave-assisted synthetic protocols. The novelty of the method is represented by the use of heavy and light DNS-isotopologue providing suitable reporter groups. Multiple-reaction monitoring has been applied in the assay of AAs in wine, pineapple juice and bergamot juice with good-to-excellent results as proved by both relative standard deviation, lower than 15%, and by the accuracy values in the range 90-110%.

Assay of tyrosol and hydroxytyrosol in olive oil by tandem mass spectrometry and isotope dilution method

Hydroxytyrosol and tyrosol, the strong antioxidant present in large amount in virgin olive oil have been assayed by LC-MS/MS under MRM condition and isotope dilution method, using d(2)-labelled internal standards obtained by simple synthetic procedures. The assay has been performed under MRM condition monitoring two transitions for each analyte to improve the specificity. This paper deals with a modern approach for assaying the content of this polyphenols in virgin olive oil down to a limit of a few hundreds of parts per billion. Tyrosol and hydroxytyrosol ranged from 10 to 47ppm and from 5 to 25ppm in commercial olive oil, respectively. The accuracy (98-107%) and analytical parameters values confirm the reliability of the proposed approach. The method can be extended to any natural matrices, including mill wastes, after a simple step of sample preparation.

Authenticity of PGI "Clementine of Calabria" by multielement fingerprint

Clementine is a citrus fruit that has found a peculiar habitat in specific areas of Calabria, a region located in southern Italy. Due to its peculiar characteristics it was recently awarded with protected geographical indications (PGI) from the European Union. In this work, stepwise linear discriminant analysis (S-LDA), soft independent modeling of class analogy (SIMCA), and partial least-squares discriminant analysis (PLS-DA) were used to build chemometric models able to protect PGI Clementine from others of different origin. Accordingly, the concentration of 24-26 elements was determined in peel and juice samples, respectively, obtained from Calabrian PGI clementine and from fruits cultivated in Algeria, Tunisia, and Spain. A cross-validation procedure has shown very satisfactory values of prediction ability for both S-LDA (96.6% for juice samples and 100% for peel samples) and SIMCA (100% for both peel and juice samples). PLS-DA models also yielded satisfactory results.

Solid phase isobaric mass tag reagent for simultaneous protein identification and assay

The solid phase isobaric mass tagging (SPIMT) approach is presented for simultaneous protein quantitation and identification. The novelty of the SPIMT strategy relies on a CID-based differentiation of regioisomeric species for quantitation of tagged proteolytic peptides. SPIMTs are unlabeled mass-tagging reagents, which consist of a reporter group, a mass balance group, and a spacer with a amine-specific reactive group, able to be linked to any N-terminal peptide. Therefore SPIMT-linked peptides from a two-plex set appear as a single unresolved precursor ion in MS, whereas the reporter groups lead to quantitation signals of m/z 168.2 and 182.2 Da upon tandem mass spectrometry (MS/MS) analysis with matrix-assisted laser desorption time-of-flight/time-of-flight (MALDI TOF/TOF). This strategy allows ease protein identification by direct submission of MS and MS/MS data to the MASCOT database. SPIMT approach showed an excellent quantitation linearity, detecting any relative concentration differences of peptides in two solutions over a 5-fold concentration range without losing sequencing information. Therefore, SPIMTs are an attractive, simple, and low cost alternative for two-plex quantitation of proteins and offer possibilities of tuning the two-plex signal mass window by replacing the spacer.

The assay of pterostilbene in spiked matrices by liquid chromatography tandem mass spectrometry and isotope dilution method

Pterostilbene (trans-3,5-dimethoxy-4-hydroxystilbene) is an active component found in several plant species, exhibiting important pharmacological properties. A new and reliable method of assaying this phyto compound in various matrices is presented; the assay is based on (1) the selectivity of liquid chromatography (LC) hyphenated with electrospray ionisation (ESI), (2) the specificity of a two-step mass spectrometric analysis (MS/MS) and (3) the accuracy of the isotope dilution method. The labelled analogue may be conveniently synthesised in a few steps. The sensitivity of the method is confirmed by the very low limit of detection (LOD) and limit of quantitation (LOQ) values achieved in the assay of pterostilbene in two distinct fortified matrices, and is further supported by the observed accuracy values.

Isotope dilution method for the assay of rotenone in olive oil and river waters by liquid chromatography/multiple reaction monitoring tandem mass spectrometry

A new approach for the assay of rotenone (1) by isotope dilution mass spectrometry is presented. The extreme toxicity of rotenone, a natural phytodrug with insecticidal and piscicidal activity, recently banned by national and international environmental protection agencies, calls for the development of sensitive and accurate methods of analyses. Accordingly, the proposed protocol is based on the availability of the labeled internal standard rotenone-d3 (3) which can be conveniently prepared by consecutive and specific mono-O-demethylation, and remethylation with methyl iodide-d3. The sensitivity of the method is confirmed by the very low limit of detection (LOD) and quantitation (LOQ) values achieved in the assay of 1 in two distinct fortified matrices, and is further supported by the observed accuracy values.

Statin-like principles of bergamot fruit (Citrus bergamia): isolation of 3-hydroxymethylglutaryl flavonoid glycosides

The 3-hydroxy-3-methylglutaryl neohesperidosides of hesperetin (brutieridin, 1) and naringenin (melitidin, 2) were isolated and detected from the fruits of bergamot (Citrus bergamia). The structures of these compounds were determined by spectroscopic and chemical methods.

Screening of dimethoate in food by isotope dilution and electrospray ionization tandem mass spectrometry

Crop control is an important issue in both developed and developing countries. An environmentally friendly approach is represented by the so-called Integrated Pest Management (IPM), whereby synthetic pesticides are only applied as a last resort, under the strict control of suitable experts. European and US regulatory authorities, such as the US EPA, are constantly assessing the risks of exposure to the organophosphate (OP) class of pesticides and, among these, specifically dimethoate. The use of dimethoate is still allowed in many crops, including olives, which once was based in the Mediterranean area but now is expanding rapidly throughout the world. An important aspect of IPM protocols is represented by the availability of reliable and sensitive methods to detect pesticides residues. This paper describes an isotope dilution dimethoate assay based on the application of electrospray ionization tandem mass spectrometry (ESI-MS/MS) by means of a deuterium-labeled internal standard.

Assay of the set of all Sudan azodye (I, II, III, IV, and Para-Red) contaminating agents by liquid chromatography-tandem mass spectrometry and isotope dilution methodology

A high-throughput mass spectrometric method is presented for the simultaneous detection of Sudan I, II, III, IV, and Para-Red azodyes in foodstuff. The method is based on the use of deuterium-labeled internal standards and atmospheric pressure chemical ionization (APCI) in a triple-quadrupole instrument. The gas-phase breakdown pattern of each labeled and unlabeled analogue displays the naphthoic moiety as a common fragment. The search for the parents of this common species (parent ion scans) allows, by flow injection and in a single run, the evaluation of the presence of each polluting species spiked in typical foodstuffs. A detailed assay of each azodye was performed by LC-APCI and isotope dilution method, through the multiple reaction monitoring approach, using deuterium-labeled internal standards. Sudan dyes can be quantified above the threshold of 10 ppb except for Sudan Para-Red, for which the limit of quantification was 20 ppb, likely due to the different ionization efficiency.

High-throughput mass spectrometry: the mechanism of sudan azo dye fragmentation by ESI tandem mass spectrometry and extensive deuterium labeling experiments

The investigation of the gas-phase chemistry of azo compounds by mass spectrometry dates back to the introduction of this peculiar research field into the armory of physical organic chemistry tools. The mechanism of the fragmentation of the azo double bond from the protonated precursor is discussed with reference to the behavior of deuterium-labeled reference compounds. The investigated molecules belong to the sudan family and the results can be used for the detection of these potential carcinogenic compounds in different matrices by means of the isotope dilution method.

Secondary metabolism of olive secoiridoids. New microcomponents detected in drupes by electrospray ionization and high-resolution tandem mass spectrometry

Olive drupe tissues have been selected as a possible source of information about the secondary metabolism of oleaceae secoiridoids. The structures of a number of new microcomponents, detected and isolated by a combined high-performance liquid chromatography (HPLC)-fraction collector/ultraviolet electrospray ionization mass spectrometry (UV/ESI-MS) apparatus, can be inferred from the data obtained by high-resolution tandem mass spectrometry in a QqTOF instrument. Some of them (1, 2, 3 and 4) are closely correlated to oleuropein. Others, such as neo-nuzhenide (5) and 2''-hydroxyoleuropein (6), typical of other oleaceae families, have never been found in olive tissues.

Characterization of new phenolic compounds from leaves of Olea europaea L. by high-resolution tandem mass spectrometry

A set of minor constituents of Olea europaea L. leaves have been identified and characterized by electrospray ionization tandem mass spectrometry (ESI-MS/MS) and high-resolution measurements (HRMS). Most of them are modified hydroxytyrosol species conjugated to a hexose unit. When possible, the structures of the new phenolic compounds present in Olea europaea L. have been confirmed by matching their MS/MS spectra with those of authentic standards isolated from other plants of the oleaceae family. The knowledge of the presence of new phenolic species in Olea europaea L. could provide tools for a full understanding of the secondary metabolism of this plant in relation to the biosynthesis of the phenolic species.

Pro-oxidant activity of oleuropein determined in vitro by electron spin resonance spin-trapping methodology

In this work, the pro-oxidant behavior of oleuropein (OLP, 1) is characterized in a Fenton-like experiment by means of ESR spectroscopy using the spin trap system DMSO and 4-(pyridyl-1-oxide)-N-tert-butyl nitrone (POBN) in phosphate buffer (PB) solution. Ferrous ions in the absence of hydrogen peroxide cause the formation of the stable nitroxide species 4 and 5 through the intermediate perferryl species. OLP displays its antioxidant activity in vitro blocking the oxidation path that leads to methoxyl radicals hence to the formation of the stable radical species 5. The role of the catechol moiety was proved when the perferryl experiments were repeated in the presence of the dimethylated oleuropein homologue (OLP-Met2, 2). The dual behavior of oleuropein, similar to that ascertained for other catechol and non-catechol natural active species, should provide warnings for its use as nutraceutical or as drug with manifold healing effects.

Absolute Method for the Assay of Oleuropein in Olive Oils by Atmospheric Pressure Chemical Ionization Tandem Mass Spectrometry

Oleuropein (OLP, 1), the active ingredient present (i) in food integrators extracted from olive leaves, (ii) in table olives, and (iii) in extra virgin olive oils is a nutraceutical whose health benefits have been widely documented. A new analytical method for its assay, which is based on the utilization of atmospheric pressure chemical ionization tandem mass spectrometry and on the use of a synthetic labeled analogue, the 4-trideuteriocarboxyoleuropein (2), as an internal standard, is presented. The results obtained with extra virgin olive oils from different cultivars and different Italian regions are discussed.

Assay of rotenone in river water by high-throughput tandem mass spectrometry and multiple-reaction monitoring methodology

The high-throughput analytical approach proposed for the assay of rotenone in lake and river waters presented here is based on atmospheric pressure chemical ionization (APCI) multiple-reaction monitoring (MRM) methodology whereby the analyte and internal standard solutions are directly analyzed, without any previous chromatographic separation. The very good accuracy is obtained by the critical choice of a reference compound that shows gas-phase chemistry similar to that of the analyte, by producing the same product ions selected for the MRM-based assay.