Natural Antioxidant Potential of Melon Peels for Fortified Foods.

Agricultural and food waste recycling reduces natural resource losses, contributing significantly to the development of new green markets through the creation of redesigned products. In order to cycle valuable molecules, the peels from Italian cantaloupe (Cucumis melo L.) cultivars were studied and successfully characterized for high-added biomolecules to verify their possible exploitation as wealthy biomasses. Peels were investigated for their cell wall-modifying and browning enzymes, as well as for total polyphenols, ortho-diphenols, flavonoids, tannins, and antioxidant properties. The results of the analyses displayed great promise in one of the three cultivars investigated. Later on, a preliminary study using the best peel extract as a dietary supplement was carried out by preparing fortified seawater to enhance its antioxidant power. The effects of storage time (60 days) were examined at two temperatures through the determination of the stability of the polyphenol content. The kinetic parameters of degradation were also calculated. The "enriched sea water" retained great antioxidant activity in refrigerated conditions, demonstrating that there is good potential for melon by-products to add their natural compounds for food fortification. These findings may provide valuable data for scale-up, from the lab to the pilot or industrial application.

Criteria and methodologies for determining the causes of swelling of canned tomatoes in tinplate containers.

This review provides the current laboratory criteria for the detection and evaluation of the possible causes of alteration of non-concentrated industrial derivatives of tomatoes (peeled tomatoes, pulps, purees, sauces, and fillets), packaged in coated or uncoated tinplate cans. We discuss how the product alterations are typically the consequence of technological errors either in the can production, or in the storage process, or in the product sterilization. The described procedures include the quantitative determination of the distribution of gases (H2 , CO2 , N2 , and O2 ) present in the headspace of the container. The gas composition and ratios can be used as markers to allow easy diagnosis of the causes of microbiologic and/or physical-chemical alterations of the tomatoes, which are usually made evident by swelling of the containers. These tests should be integrated by microbiological analyses aimed at a restricted group of microorganisms, with the chemical analysis of the container and the chemical analysis of the altered product. By way of example, we report the assessment of the causes of alteration in four different case-studies.

Monitoring antioxidants by coulometry: Quantitative assessment of the strikingly high antioxidant capacity of bergamot (Citrus bergamia R.) by-products.

A recently optimized rapid, cheap, and accurate coulometric method has been exploited to determine the antioxidant capacity of bergamot (Citrus bergamia Risso) by-products, including first (FPJ) and second press juices (SPJ), in comparison to analogous products from several citrus species. Extracts from the entire edible part (i.e., juice and pulp) and de-oiled peel of bergamot were also assayed. The Coulometrically Determined Antioxidant Capacity (CDAC) data, expressed as moles of electrons per mass of sample, were evaluated with other parameters such as total phenolic compounds, ascorbic acid, total carotenoids, and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical inhibition. The CDAC of bergamot FPJ (39 mmol e- kg-1) was comparable with other citrus juices (20-65 mmol e- kg-1 range), whereas the CDAC of bergamot SPJ (816 mmol e- kg-1) was strikingly higher than the counterparts from other citrus fruits. This value approached that of bergamot peel extracts (822 mmol e- kg-1). Bergamot peel and SPJ also exhibited the highest DPPH inhibition. The CDAC values were associated with the HPLC-determined content of flavonoids, namely neoeriocitrin, naringin, and neohesperidin, which were 4-10-fold more concentrated in bergamot SPJ and peel than in SPJ from other citrus species. These findings contribute to point at bergamot by-products as rich sources of antioxidant compounds on a quantitative basis, highlighting their enormous potential for pharmaceutical, nutraceutical and food applications.

SIRT3 Modulates Endothelial Mitochondrial Redox State during Insulin Resistance.

Emerging evidence indicates that defects in sirtuin signaling contribute to impaired glucose and lipid metabolism, resulting in insulin resistance (IR) and endothelial dysfunction. Here, we examined the effects of palmitic acid (PA) treatment on mitochondrial sirtuins (SIRT2, SIRT3, SIRT4, and SIRT5) and oxidative homeostasis in human endothelial cells (TeloHAEC). Results showed that treatment for 48 h with PA (0.5 mM) impaired cell viability, induced loss of insulin signaling, imbalanced the oxidative status (p < 0.001), and caused negative modulation of sirtuin protein and mRNA expression, with a predominant effect on SIRT3 (p < 0.001). Restoration of SIRT3 levels by mimic transfection (SIRT3+) suppressed the PA-induced autophagy (mimic NC+PA) (p < 0.01), inflammation, and pyroptosis (p < 0.01) mediated by the NLRP3/caspase-1 axis. Moreover, the unbalanced endothelial redox state induced by PA was counteracted by the antioxidant δ-valerobetaine (δVB), which was able to upregulate protein and mRNA expression of sirtuins, reduce reactive oxygen species (ROS) accumulation, and decrease cell death. Overall, results support the central role of SIRT3 in maintaining the endothelial redox homeostasis under IR and unveil the potential of the antioxidant δVB in enhancing the defense against IR-related injuries.

Diet-derived ergothioneine induces necroptosis in colorectal cancer cells by activating the SIRT3/MLKL pathway.

Ergothioneine (Egt) is a dietary amino acid which acts as an antioxidant to protect against ageing-related diseases. We investigated the anti-cancer properties of Egt in colorectal cancer cells (CRC). Egt treatment exerted cytotoxicity in a dose-dependent manner, induced reactive oxygen species accumulation, loss of mitochondrial membrane potential and upregulation of the histone deacetylase SIRT3. Immunoblotting analysis indicated that the cell death occurred via necroptosis through activation of the RIP1/RIP3/MLKL pathway. An immunoprecipitation assay unveiled that the interaction between the terminal effector in necroptotic signalling MLKL and SIRT3 increased during the Egt treatment. SIRT3 gene silencing blocked the upregulation of MLKL and abolished the ability of Egt to induce necroptosis. The SIRT3-MLKL interaction may mediate the necroptotic effects of Egt in CRC, suggesting the potential of this dietary amino thione in the prevention of CRC.

Colorectal Cancer Apoptosis Induced by Dietary δ-Valerobetaine Involves PINK1/Parkin Dependent-Mitophagy and SIRT3.

Understanding the mechanisms of colorectal cancer progression is crucial in the setting of strategies for its prevention. δ-Valerobetaine (δVB) is an emerging dietary metabolite showing cytotoxic activity in colon cancer cells via autophagy and apoptosis. Here, we aimed to deepen current knowledge on the mechanism of δVB-induced colon cancer cell death by investigating the apoptotic cascade in colorectal adenocarcinoma SW480 and SW620 cells and evaluating the molecular players of mitochondrial dysfunction. Results indicated that δVB reduced cell viability in a time-dependent manner, reaching IC50 after 72 h of incubation with δVB 1.5 mM, and caused a G2/M cell cycle arrest with upregulation of cyclin A and cyclin B protein levels. The increased apoptotic cell rate occurred via caspase-3 activation with a concomitant loss in mitochondrial membrane potential and SIRT3 downregulation. Functional studies indicated that δVB activated mitochondrial apoptosis through PINK1/Parkin pathways, as upregulation of PINK1, Parkin, and LC3B protein levels was observed (p < 0.0001). Together, these findings support a critical role of PINK1/Parkin-mediated mitophagy in mitochondrial dysfunction and apoptosis induced by δVB in SW480 and SW620 colon cancer cells.

Assessment of free plant sterols in cold pressed Citrus essential oils.

A fast, sensitive, accurate and robust GC-FID and confirmatory GC-MS method, was developed to simultaneously determine squalene and underivatized free plant sterols in Citrus essential oils (cEOs). The method was applied to assess the content of squalene and free plant sterols in four most commonly employed cold-pressed cEOs (bergamot, lemon, mandarin and orange). cEOs plant sterols exhibited distinctive molecular patterns, with levels ranging from 182 to 1100 mg kg-1 in lemon and bergamot essential oils, respectively. ß-sitosterol was the dominant compound in all cases, with an average content of ∼650 mg kg-1 in bergamot and orange essential oils. Campesterol and brassicasterol occurred at much lower amount in all samples. Bergamot essential oil was also the richest in squalene (537 mg kg-1) compared to the other cEOs. The method developed could contribute to define compositional patterns of cEOs, thus supporting their versatile utilisation in the food and flavour industry.

Amino acids, betaines and related ammonium compounds in Neapolitan limmo, a Mediterranean sweet lime, also known as lemoncetta Locrese.

BACKGROUND: The so-called 'Neapolitan limmo' or 'lemoncetta Locrese' is an old and now rare Mediterranean sweet lime, similar to lemon but smaller. It is a fruit distinguished from orange, lemon, mandarin, and lime for its sweeter, watery, and non-acidic taste, with a pH between 5.6 and 5.9. No compositional studies are currently available for this citrus fruit. Here we report, for the first time, the distribution in the limmo juice of free amino acids and their main derivatives such as betaines and related ammonium compounds. RESULTS: Seven proteinogenic amino acids (proline, asparagine, serine, aspartic acid, glutamine, alanine, and threonine) and a non-protein amino acid (γ-aminobutyric acid) characterize Neapolitan limmo juice. Proline betaine is the predominant betaine. The data were compared with those of other important citrus juices. CONCLUSION: The specific 'taste quality' of Neapolitan limmo juice can be attributed to its peculiar composition in amino acids. The species-specific presence of the ammonium compound derivatives of the amino acid proline, with proline betaine as the predominant betaine, characterize the non-acidic varieties of Mediterranean sweet lime. Our study constitutes an important step towards the repopulation of this ancient plant and its exploitation in food industry. © 2020 Society of Chemical Industry.

Chemometric Screening of Fourteen Essential Oils for Their Composition and Biological Properties.

Essential oils (EOs) obtained from aromatic plants are widely used worldwide, especially in cosmetic and food products due to their aroma and biological properties and health benefits. Some EOs have significant antimicrobial and antioxidant activities, and thus could effectively increase the shelf lives of foodstuff and beverages. In this study, fourteen essential oils (clove, eucalyptus, fennel, lavender, oregano, palmarosa, pepper, star anise, tea tree, turmeric, Chinese yin yang, Japanese yin yang, and ylang ylang) from different medicinal plant families were screened by gas-chromatography-mass spectrometry (GC-MS) for their different chemical profiles and bioassays were performed to assess their antifungal and antioxidant activities. The results obtained were assessed by principal component analysis (PCA). PCA distinguished six groups characterized by different terpene chemotypes. Amongst the EOs studied, the clove EO showed the strongest antioxidant activity characterized by an EC50 of 0.36 µL/mL. The oregano EO had the greatest antiyeast activity characterized by a minimal inhibitory concentration of 10 µL/mL. In conclusion, clove and oregano EOs are strong antifungal and antioxidant agents, respectively, with great potential in the food industry to avoid spoilage and to increase shelf life.

Synergistic Effect of Dietary Betaines on SIRT1-Mediated Apoptosis in Human Oral Squamous Cell Carcinoma Cal 27.

Betaines are food components widely distributed in plants, animals, microorganisms, and dietary sources. Among betaines, δ-valerobetaine (N,N,N-trimethyl-5-aminovaleric acid, δVB) shares a metabolic pathway common to γ-butyrobetaine (γBB). The biological properties of δVB are particularly attractive, as it possesses antioxidant, anti-inflammatory and anticancer activities. Here, we investigated the possible synergism between δVB and the structurally related γBB, to date unexplored, by testing the in vitro anticancer activity in head and neck squamous cell carcinoma cell lines, FaDu, UM-SCC-17A and Cal 27. Among cell lines tested, results indicated that betaines showed the highest effect in reducing Cal 27 cell proliferation up to 72 h (p < 0.01). This effect was enhanced when betaines were administered in combination (δVB plus γBB) (p < 0.001). Inhibition of cell growth by δVB plus γBB involved reactive oxygen species (ROS) accumulation, upregulation of sirtuin 1 (SIRT1), and apoptosis (p < 0.001). SIRT1 gene silencing by small interfering RNA decreased the apoptotic effect of δVB plus γBB by modulating downstream procaspase-3 and cyclin B1 (p < 0.05). These findings might have important implications for novel prevention strategies for tongue squamous cell carcinoma by targeting SIRT1 with naturally occurring betaines.

The Effect of Processing Methods on Phytochemical Composition in Bergamot Juice.

Experimental and epidemiological studies show a positive relation between consumption of citrus juices and reduction of risk for some chronic disorders, such as diabetes and cardiovascular diseases. In particular, the bergamot juice is characterized by noticeable amounts of phytochemicals such as flavanone glycosides, limonoids, and quaternary ammonium compounds, all health-beneficial biomolecules. In vitro and in vivo studies have shown anti-inflammatory, cholesterol-lowering, and anti-diabetic activities attributed to these compounds depending on their chemical structure. However, nutritional content of bergamot juice may vary as consequence of different processing techniques, thus needing to address this claim. For this reason, the objective of this research was to evaluate the effects of different processing systems on the proximate constituents, the composition, and the antioxidant activity of the correspondent juices. Overall, the results indicate that the process employed may influence the chemical composition and the functional properties of the ended juice. Screw press method produced a juice with greater content of flavanone glycosides (ranged from 37 to 402 mg/L) and limonoid aglycones (ranged from 65 to 67 mg/L) than the other processes (p < 0.001). However, the process used for extraction of bergamot juice did not affect significantly the N,N-dimethyl-L-proline content (p < 0.5). Moreover, the screw press juice showed the highest antioxidant activity with EC50 value of 9.35 µg/mL, thus suggesting that this method maintains for health the nutritional quality of a fresh-pressed juice.

Characterization of Polyphenolic Compounds in Cantaloupe Melon By-Products.

The Muskmelon (Cucumis melo L.), which includes several crops of great economic importance worldwide, belongs to the Cucurbitaceae family, and it is well recognized for culinary and medicinal purposes. The high fruit consumption produces a large quantity of waste materials, such as peels and seeds that are still rich in molecules like polyphenols, carotenoids, and other biologically active components that possess a positive influence on human health and wellness. A sustainable development in agro-food and agro-industry sectors could come through the reutilization and valorization of these wastes, which in turn, could result in reducing their environmental impact. The current study provides a biochemical characterization of cantaloupe by-products, peels and seeds, through evaluating total polyphenols, ortho-diphenols, flavonoids, and tannins content. Furthermore, the antioxidant activity was assessed in order to understand potential benefits as natural antioxidants. Overall, the peel extract revealed the highest radical's scavenging and reducing activities, moreover, it showed higher polyphenolic content than seed extract as revealed by both cromatographic and spectrophotometric analyses. The results of the present study indicate that the melon residues are a good source of natural phytochemicals useful for many purposes, such as ingredients for nutraceutic, cosmetic, or pharmaceutical industries, development of functional ingredients and new foods, and production of fertilizers and animal feed.

Characterization of essential oil recovered from fennel horticultural wastes.

Fennel crop has been traditionally used as spice in cooking and fragrances, and in folk medicine for its spectrum of useful properties. Mediterranean is the elective natural cultivation area for this plant with Italy being a leader producer. A limit of this production is due to the high amount of wastes derived still rich of phytochemicals, which are usually underused. Hence, the extraction and characterization of essential oil from residues of fennel horticultural market was investigated to understand the potential profit of their recycling. Forty-eight compounds resulted for fennel oil waste, analysed by GC-FID-MS, with the most abundant among components was anethole. Other constituents contributing to fennel flavour were the monoterpenes limonene and nerol. The exploitation of this oil as a good source of bioactive compounds was assessed by means of its antioxidant power measured with DPPH test.

The Ancient Neapolitan Sweet Lime and the Calabrian Lemoncetta Locrese Belong to the Same Citrus Species.

"Neapolitan limmo" is an ancient and rare sweet Mediterranean lime, now almost extinct but used until a few decades ago for the production of a fragrant liqueur called the "four citrus fruits". The objective of this work was to compare, through the use of chemical (flavonoids, volatile organic compounds, and chiral compounds) and molecular (DNA fingerprint based on RAPD-PCR) markers, the residual population of Neapolitan limmo with other populations of sweet limes, identified in Calabria and known as "lemoncetta Locrese". We report for the first time specific botanical characteristics of the two fruits and unequivocally show that the ancient sweet Mediterranean limes Neapolitan limmo and lemoncetta Locrese are synonyms of the same Citrus species. Owing to the biodiversity conserved in their places of origin, it will now be possible to recover, enhance and implement the use of this ancient sweet lime for agro-industrial purposes.

Carnitine Precursors and Short-Chain Acylcarnitines in Water Buffalo Milk.

Ruminants' milk contains δ-valerobetaine originating from rumen through the transformation of dietary Nε-trimethyllysine. Among ruminant's milk, the occurrence of δ-valerobetaine, along with carnitine precursors and metabolites, has not been investigated in buffalo milk, the second most worldwide consumed milk, well-known for its nutritional value. HPLC-ESI-MS/MS analyses of bulk milk revealed that the Italian Mediterranean buffalo milk contains δ-valerobetaine at levels higher than those in bovine milk. Importantly, we detected also γ-butyrobetaine, the l-carnitine precursor, never described so far in any milk. Of interest, buffalo milk shows higher levels of acetylcarnitine, propionylcarnitine, butyrylcarnitine, isobutyrylcarnitine, and 3-methylbutyrylcarnitine (isovalerylcarnitine) than cow milk. Moreover, buffalo milk shows isobutyrylcarnitine and butyrylcarnitine at a 1-to-1 molar ratio, while in cow's milk this ratio is 5 to 1. Results indicate a peculiar short-chain acylcarnitine profile characterizing buffalo milk, widening the current knowledge about its composition and nutritional value.

Ruminant meat and milk contain δ-valerobetaine, another precursor of trimethylamine N-oxide (TMAO) like γ-butyrobetaine.

Quaternary ammonium compounds containing N-trimethylamino moiety, such as choline derivatives and carnitine, abundant in meat and dairy products, are metabolic precursors of trimethylamine (TMA). A similar fate is reported for Nε-trimethyllysine and γ-butyrobetaine. With the aim at investigating the metabolic profile of such metabolites in most employed animal dietary sources, HPLC-ESI-MS/MS analyses on ruminant and non-ruminant milk and meat were performed. Results demonstrate, for the first time, the presence of δ-valerobetaine, occurring at levels higher than γ-butyrobetaine in all ruminant samples compared to non-ruminants. Demonstration of δ-valerobetaine metabolic origin, surprisingly, showed that it originates from rumen through the transformation of dietary Nε-trimethyllysine. These results highlight our previous findings showing the ubiquity of free Nε-trimethyllysine in vegetable kingdom. Furthermore, δ-valerobetaine, similarly to γ-butyrobetaine, can be degraded by host gut microbiota producing TMA, precursor of the proatherogenic trimethylamine N-oxide (TMAO), unveiling its possible role in the biosynthetic route of TMAO.

Ophthalmic acid is a marker of oxidative stress in plants as in animals.

BACKGROUND: Ophthalmic acid (OPH), γ-glutamyl-L-2-aminobutyryl-glycine, a tripeptide analogue of glutathione (GSH), has recently captured considerable attention as a biomarker of oxidative stress in animals. The OPH and GSH biosynthesis, as well as some biochemical behaviors, are very similar. Here, we sought to investigate the presence of OPH in plants and its possible relationship with GSH, known to possess multiple functions in the plant development, growth and response to environmental changes. METHODS: HPLC-ESI-MS/MS analysis was used to examine the occurrence of OPH in leaves from various plant species, and flours from several plant seeds. Different types of oxidative stress, i.e., water, dark, paraquat, and cadmium stress, were induced in rye, barley, oat, and winter wheat leaves to evaluate the effects on the levels of OPH and its metabolic precursors. RESULTS: OPH and its dipeptide precursor, γ-glutamyl-2-aminobutyric acid, were found to occur in phylogenetically distant plants. Interestingly, the levels of OPH were tightly associated with the oxidative stress tested. Levels of OPH precursors, γ-glutamyl-2-aminobutyric acid and 2-aminobutyric acid, the latter efficiently formed in plants via biosynthetic pathways absent in the animal kingdom, were also found to increase during oxidative stress. CONCLUSIONS: OPH occurs in plants and its levels are tightly associated with oxidative stress. GENERAL SIGNIFICANCE: OPH behaves as an oxidative stress marker and its biogenesis might occur through a biochemical pathway common to many living organisms.

The betaine profile of cereal flours unveils new and uncommon betaines.

We report the LC-ESI-MS/MS determination of betaines in commercial flours of cereals and pseudocereals most utilized in human nutrition. Results showed that glycine betaine, trigonelline, proline betaine, Nε-trimethyllysine were metabolites common to all examined flours, whereas an uncommon betaine, valine betaine, and glutamine betaine were present only in flours of barley, rye, oat, durum wheat, winter wheat, Triticum dicoccum and Triticum monococcum. Valine betaine and glutamine betaine, the latter never reported before in plants and animals, are not evenly distributed in the Poaceae family, but their presence or absence in flours depends on the subfamily to which the plant belongs. Interestingly, we also report for the first time the occurrence of pipecolic acid betaine (homostachydrine) and its precursor 1,2-N-methylpipecolic acid in rye flour. These two metabolites were not detected in any other cereal or pseudocereal flour, suggesting their potential role as markers of rye flour occurrence in cereal-based foods.

Ergothioneine products derived by superoxide oxidation in endothelial cells exposed to high-glucose.

Ergothioneine (Egt), 2-mercapto-L-histidine betaine (ESH), is a dietary component acting as antioxidant and cytoprotectant. In vitro studies demonstrated that Egt, a powerful scavenger of hydroxyl radicals, superoxide anion, hypochlorous acid and peroxynitrite, protects vascular function against oxidative damages, thus preventing endothelial dysfunction. In order to delve the peculiar oxidative behavior of Egt, firstly identified in cell free-systems, experiments were designed to identify the Egt oxidation products when endothelial cells (EC) benefit of its protection against high-glucose (hGluc). HPLC-ESI-MS/MS analyses revealed a decrease in the intracellular GSH levels and an increase in the ophthalmic acid (OPH) levels during hGluc treatment. Interestingly, in the presence of Egt, the decrease of the GSH levels was lower than in cells treated with hGluc alone, and this effect was paralleled by lower OPH levels. Egt was also effective in reducing the cytotoxicity of H2O2 and paraquat (PQT), an inducer of superoxide anion production, showing a similar time-dependent pattern of GSH and OPH levels, although with peaks occurring at different times. Importantly, Egt oxidation generated not only hercynine (EH) but also the sulfonic acid derivative (ESO3H) whose amounts were dependent on the oxidative stress employed. Furthermore, cell-free experiments confirmed the formation of both EH and ESO3H when Egt was reacted with superoxide anion. In summary, these data, by identifying the EH and ESO3H formation in EC exposed to hGluc, highlight the cellular antioxidant properties of Egt, whose peculiar redox behavior makes it an attractive candidate for the prevention of oxidative stress-associated endothelial dysfunction during hyperglycemia.

Tyramine Pathways in Citrus Plant Defense: Glycoconjugates of Tyramine and Its N-Methylated Derivatives.

Glucosylated forms of tyramine and some of its N-methylated derivatives are here reported for the first time to occur in Citrus genus plants. The compounds tyramine-O-ß-d-glucoside, N-methyltyramine-O-ß-d-glucoside, and N,N-dimethyltyramine-O-ß-d-glucoside were detected in juice and leaves of sweet orange, bitter orange, bergamot, citron, lemon, mandarin, and pomelo. The compounds were identified by mass spectrometric analysis, enzymatic synthesis, and comparison with extracts of Stapelia hirsuta L., a plant belonging to the Apocynaceae family in which N,N-dimethyltyramine-O-ß-d-glucoside was identified by others. Interestingly, in Stapelia hirsuta we discovered also tyramine-O-ß-d-glucoside, N-methyltyramine-O-ß-d-glucoside, and the tyramine metabolite, N,N,N-trimethyltyramine-O-ß-glucoside. However, the latter tyramine metabolite, never described before, was not detected in any of the Citrus plants included in this study. The presence of N-methylated tyramine derivatives and their glucosylated forms in Citrus plants, together with octopamine and synephrine, also deriving from tyramine, supports the hypothesis of specific biosynthetic pathways of adrenergic compounds aimed to defend against biotic stress.