Phenolic composition, antioxidant potential and health benefits of citrus peel

UHPLC-Q-TOF-MS/MS-based Metabolite Profiling of Ganpu Tea in Rat Urine and Feces

Ganpu tea is a novel type of beverage produced from Pu-erh tea stuffed in the pericarp of Citrus reticulata “Chachi”. It has gained considerable popularity in China owing to its inviting flavor and health effects. However, the in vivo metabolites of Ganpu tea, which may contribute to its overall health effects, are still unclear. In the present work, rat urine and feces samples were collected after oral administration of Ganpu tea extract (GTE), and then subjected to ultra-high-performance liquid chromatography/quadrupole-time-of-flight tandem mass spectrometry (UHPLC-Q-TOF-MS/MS)-based metabolite profiling. As a result, 27 prototype compounds and 41 metabolites derived from caffeic acid, gallic acid, p-coumaric acid, xanthine, catechin, polymethoxyflavone, (PMF) flavanone, and flavone were identified in rat urine and feces. Based on the detected metabolites, the ingested prototype compounds derived from Ganpu tea were found to undergo extensive phase II metabolism in rats, especially and sulfation. These results will be valuable for interpreting the health effects of Ganpu tea.

Effects of food matrix elements (dietary fibres) on grapefruit peel flavanone profile and on faecal microbiota during in vitro fermentation

Citrus fruits are a good source of flavanones. The present study aimed to assess the effect of food matrix elements [dietary fibres (DFs)] on the flavanone profile of grapefruit peel (GFP) and on the gut microbiota during in vitro digestion and simulated colonic fermentation. The contents of low-molecular-weight metabolites (dihydrocaffeic acid and 3-phenylpropionic acid) were increased by pectin, konjac and chitosan in medium- and high-viscosity matrices. Compared with the GFP group, the counts of Lactobacillus spp. and Clostridium leptum were significantly increased in medium-viscosity food matrices (konjac and chitosan) (p < 0.05). Moreover, the acetic and propionic acid contents were significantly elevated in the GFP + DF groups after 12 h of fermentation (p < 0.05). GFP flavanones were retained by DF, and the total phenolic content (TPC) and antioxidant potency composite (APC) index decreased during in vitro digestion. These findings indicate that medium-viscosity DFs (konjac and chitosan) could act as key food matrix elements for the retention of polyphenols.

Fruit peel bioactives, valorisation into nanoparticles and potential applications: A review

Nanotechnology is a rapidly growing field with profound applications in different domains, particularly in food science and technology. Nanoparticles (NPs) synthesis, an integral part of nanotechnology-based applications, is broadly classified into chemical, physical and biosynthesis methods. Chemically sensitive and energy-intensive procedures employed for NPs synthesis are some of the limits of traditional chemical approaches. Recent research has focused on developing easy, nontoxic, cost-effective, and environment-friendly NPs synthesis during the last decade. Biosynthesis approaches have been developed to achieve this goal as it is a viable alternative to existing chemical techniques for the synthesis of metallic nanomaterials. Fruit peels contain abundant bioactive compounds including phenols, flavonoids, tannins, triterpenoids, steroids, glycosides, carotenoids, anthocyanins, ellagitannins, vitamin C, and essential oils with substantial health benefits, anti-bacterial and antioxidant properties, generally discarded as byproduct or waste by the fruit processing industry. NPs synthesized using bioactive compounds from fruit peel has futuristic applications for an unrealized market potential for nutraceutical and pharmaceutical delivery. Numerous studies have been conducted for the biosynthesis of metallic NPs such as silver (AgNPs), gold (AuNPs), zinc oxide, iron, copper, palladium and titanium using fruit peel extract, and their synthesis mechanism have been reported in the present review. Additionally, NPs synthesis methods and applications of fruit peel NPs have been discussed.

Chemical Variation of Chenpi (Citrus Peels) and Corresponding Correlated Bioactive Compounds by LC-MS Metabolomics and Multibioassay Analysis

The peel of Citrus reticulata “Chachi” (CP) possesses various health-promoting benefits and is not only one of the most famous Chinese herbal medicine, but also an ingredient in fermented foods. In the present study, the effects of storage years (1-, 3-, 4-, 5-, 6-, and 11-years) on the chemical profiling and potential bioactive compounds of CP were compared by metabolomics and in vitro bioactivity analysis. With the increase of storage time, the content of hesperidin significantly decreased, but nobiletin, 3,5,6,7,8,3′,4′-heptamethoxyflavone, and tangeretin were increased. Meanwhile, the antioxidant activity of CP was enhanced. Phenolic acids, flavonol glycosides, fatty acids, and alkyl glycosides were marker compounds that were responsible for distinguishing the storage time of CP. Correlation analysis suggested that some polyphenols including quercetin-glucoside, quinic acid, trihydroxydimethoxyflavone, and rutin were potential antioxidant compounds in CP. The dichloromethane and n-butanol fractions showed the better antioxidant capacity and inhibitory effects on glucose-hydrolysis enzymes. They mainly contained ferulic acid, nobiletin, 3,5,6,7,8,3′,4′-heptamethoxyflavone, kaempferol, and hesperidin.

Ultrasound-assisted green synthesis of gold nanoparticles using citrus peel extract and their enhanced anti-inflammatory activity

Ultrasound and plant extract are two green approaches that have been used to synthesize gold nanoparticles (AuNPs); however, how the combination of ultrasound and citrus peel extract (CPE) affects the structure characteristics and the bioactivity of AuNPs remains unknown. Here we investigated the effects of ultrasound conditions on the particle size, stability, yield, phenolic encapsulation efficacy, and the anti-inflammatory activity of AuNPs. The results showed that temperature was positively correlated to the particle size and the anti-inflammatory activity of synthesized AuNPs. Increasing the power intensity significantly decreased the particle size, while increased the change of total phenolic content (ΔTPC) in the reaction mixture. The increase of ΔTPC caused the enhanced anti-inflammatory activity of AuNPs. The AuNPs synthesized with or without ultrasound treatment were characterized using UV-Vis, DLS, SEM, TEM, EDS, XRD, and FT-IR. The result verified the formation of negatively charged, spherical, stable, and monodispersed AuNPs. AuNPs synthesized with ultrasound (AuNPs-U) has smaller particle size (13.65 nm vs 16.80 nm), greater yield and anti-inflammatory activity (IC₅₀, 82.91 vs 157.71 μg/mL) than its non-ultrasound counterpart (AuNPs-NU). HPLC analysis showed that hesperidin was the key reductant for the synthesis of AuNPs. AuNPs-U also inhibited the mRNA and protein expression of iNOS and COX-2 in the LPS-induced Raw 264.7 cells. Our research elucidates the relationship between the reaction conditions and the structure characteristics and the anti-inflammatory activity of AuNPs synthesized using CPE with the help of ultrasound, thereafter, provides a feasible and economic way to synthesize AuNPs that can be used to ameliorate inflammation.

Bioactive Compounds of Citrus Fruits: A Review of Composition and Health Benefits of Carotenoids, Flavonoids, Limonoids, and Terpenes

The increased consumption of fruits, vegetables, and whole grains contributes to the reduced risk of many diseases related to metabolic syndrome, including neurodegenerative diseases, cardiovascular disease (CVD), diabetes, and cancer. Citrus, the genus Citrus L., is one of the most important fruit crops, rich in carotenoids, flavonoids, terpenes, limonoids, and many other bioactive compounds of nutritional and nutraceutical value. Moreover, polymethoxylated flavones (PMFs), a unique class of bioactive flavonoids, abundantly occur in citrus fruits. In addition, citrus essential oil, rich in limonoids and terpenes, is an economically important product due to its potent antioxidant, antimicrobial, and flavoring properties. Mechanistic, observational, and intervention studies have demonstrated the health benefits of citrus bioactives in minimizing the risk of metabolic syndrome. This review provides a comprehensive view of the composition of carotenoids, flavonoids, terpenes, and limonoids of citrus fruits and their associated health benefits.

A Rapid LC-MS/MS Method for Simultaneous Determination of Ten Flavonoid Metabolites of Naringin in Rat Urine and Its Application to an Excretion Study

Naringin is a dietary flavonoid glycoside with multiple bioactivities. It has been involved in numerous metabolism and excretion studies, and its metabolic properties are clear. However, information concerning the excretion profile of its original metabolites are still scarce, and few methods for simultaneous determination of multiple original metabolites of naringin in biological samples have been reported so far. In this study, a rapid and sensitive method for simultaneous determination of ten flavonoid metabolites of naringin in rat urine was developed with an UHPLC-Q-Trap-MS/MS system. One-step protein precipitation method with acetonitrile was used to extract analytes. A rapid chromatographic separation within 11 min was performed on an ACQUITY UPLC^® BEH C₁₈ column (2.1 mm × 50 mm, 1.7 μm) using gradient elution with a mobile phase of water and methanol, both with 0.1% formic acid (v/v). MS/MS detection was conducted in negative ion mode and multiple reactions monitoring scanning mode. The analytical method was fully validated and successfully applied to monitor the excretion profiles of naringin in rat urine. Quantitative results revealed the visible individual difference and low urinary recovery of flavonoid metabolites in the excretion of naringin, which may be helpful for further study to understand the in vivo behavior and action mechanism of naringin.

Antioxidant Activity of Milk and Dairy Products

The aim of the study was to present a review of literature data on the antioxidant potential of raw milk and dairy products (milk, fermented products, and cheese) and the possibility to modify its level at the milk production and processing stage. Based on the available reports, it can be concluded that the consumption of products that are a rich source of bioactive components improves the antioxidant status of the organism and reduces the risk of development of many civilization diseases. Milk and dairy products are undoubtedly rich sources of antioxidant compounds. Various methods, in particular, ABTS, FRAP, and DPPH assays, are used for the measurement of the overall antioxidant activity of milk and dairy products. Research indicates differences in the total antioxidant capacity of milk between animal species, which result from the differences in the chemical compositions of their milk. The content of antioxidant components in milk and the antioxidant potential can be modified through animal nutrition (e.g., supplementation of animal diets with various natural additives (herbal mixtures, waste from fruit and vegetable processing)). The antioxidant potential of dairy products is associated with the quality of the raw material as well as the bacterial cultures and natural plant additives used. Antioxidant peptides released during milk fermentation increase the antioxidant capacity of dairy products, and the use of probiotic strains contributes its enhancement. Investigations have shown that the antioxidant activity of dairy products can be enhanced by the addition of plant raw materials or their extracts in the production process. Natural plant additives should therefore be widely used in animal nutrition or as functional additives to dairy products.

Citrus depressa Hayata Peel Ameliorates Nonalcoholic Fatty Liver and Modulates the Hepatic Drug-metabolizing Enzymes and Transporters in Rats Fed a High-fat Diet

Citrus depressa Hayata is a small, green citrus fruit native to Taiwan and Japan. The citrus peel contains polymethoxylated flavones, including nobiletin and tangeretin, and might have strong antioxidant and...

The use of orange peel in the technology of drinks fermentation

Nutrition is one of the most important factors determining human health. Enrichment of food products with minerals, antioxidant compounds, and vitamins are relevant today. In this work, dry orange peel was used to enrich a fermented drink based on kvass wort with phenolic compounds and vitamin C. The following indicators were determined: the content of vitamin C, the amount of phenolic compounds and anthocyanins, the antioxidant activity of orange peel dried to a moisture content of 18%. The drink fermentation lasted 12 hours at 30 °C. Secondary fermentation was carried out for 48 hours. At this stage, orange peel was added in the amount of 10 g/l. During the experiment, the concentration of dry matter content, the acidity of the medium, and the content of ethyl alcohol were measured. Organoleptic indicators were determined during the tasting of the finished product. In the finished drink, the content of ethyl alcohol was 0.98%. It was found that the finished drink with peel contains 4 times more phenolic compounds and 1.5 times more vitamin C.

New electrolyte beverages prepared by the citrus canning processing water through chemical improvement

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Citrus segment membrane removal during canning was improved for clean process.

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The improved process using mixed acid (alkali) showed good membrane removal result.

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The processing water was fully used for preparing a new healthy electrolyte drink.

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The bioactive compounds in the canning processing water were completely recoverd.

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This green process with economic viability has great society benefits.

In the production of canned citrus, large amounts of processing water were discharged during the segment membrane removal process, causing severe pollution. In order to reduce pollution and recover the bioactive compounds in the processing water, the production of canned satsuma mandarin, sweet orange and grapefruit were studied, and improved acid (0.1% HCl, 0.4% citric acid) and alkali (0.1% KOH, 0.2% NaOH) were used to conduct the new chemical hydrolysis process to remove the segment membrane. The obtained acid and alkali processing water were firstly explored the potential to make novel beverages, which contain electrolytes (Na: 472–945 ppm; K: 208–279 ppm; Cl: 364–411 ppm; citrate: 1105–1653 ppm) and potential prebiotics such as pectin and flavonoids. The improved segment membrane removal process realized the conversion of wastewater into drinkable beverages at low costs. The bioactive compounds were fully recovered without wastewater discharging, which produced great environmental, economic and health value.

By-Products Revalorization with Non-Thermal Treatments to Enhance Phytochemical Compounds of Fruit and Vegetables Derived Products: A Review

The aim of this review is to provide comprehensive information about non-thermal technologies applied in fruit and vegetables (F&V) by-products to enhance their phytochemicals and to obtain pectin. Moreover, the potential use of such compounds for food supplementation will also be of particular interest as a relevant and sustainable strategy to increase functional properties. The thermal instability of bioactive compounds, which induces a reduction of the content, has led to research and development during recent decades of non-thermal innovative technologies to preserve such nutraceuticals. Therefore, ultrasounds, light stresses, enzyme assisted treatment, fermentation, electro-technologies and high pressure, among others, have been developed and improved. Scientific evidence of F&V by-products application in food, pharmacologic and cosmetic products, and packaging materials were also found. Among food applications, it could be mentioned as enriched minimally processed fruits, beverages and purees fortification, healthier and "clean label" bakery and confectionary products, intelligent food packaging, and edible coatings. Future investigations should be focused on the optimization of 'green' non-thermal and sustainable-technologies on the F&V by-products' key compounds for the full-utilization of raw material in the food industry.

Citrus Peel Extracts for Industrial-Scale Production of Bio-Based Active Food Packaging

The thermal stability of four different commercial citrus peel extracts was tested and improved by an encapsulation process with β-cyclodextrins in a spray-dryer. All extracts after the encapsulation process maintained a good antioxidant capacity, with an apparent loss in total phenolic compounds of around 20–25%. In addition, all samples showed good antimicrobial activity (MIC 5–0.625 mg/mL) against Staphylococcus aureus, which was maintained after the encapsulation process (MIC 5–1.25 mg/mL). Based on the antioxidant and antimicrobial activity results, the best-encapsulated citrus extract was selected for incorporation into a polylactic acid/polyhydroxy butyrate (PLA/PHB) film. The latter was then produced on an industrial scale by cast extrusion and was found to be suitable for food contact as it showed overall migration values in different food simulants lower than the legislative limit of 10 mg of non-volatile substances per 1 dm² of surface area. The UHPLC-HRMS analysis, performed to evaluate the migration of the active compounds, revealed about 13.41% release in food simulant A and 11.02% in food simulant B. Antimicrobial analysis conducted directly on the film showed a growth inhibition activity towards Escherichia coli and Staphylococcus aureus equal to 30 and 60%, respectively.

Headspace volatolome of peel flours from citrus fruits grown in Brazil

Citrus fruit peel comprises a pleasant mix of volatile compounds together with fibers, nutrients, and bioactive compounds. Therefore, it has great potential for use as a food ingredient. Studies evaluating the volatile composition of citrus peel flours are limited for most citruses. The goal of this study was to characterize, by HS-SPME/GC-MS, the volatile profile of citrus peel flours made from fruits commonly grown in Brazil. Two composite samples of ten types of citrus peel flours from consecutive harvests were evaluated. 69 volatile compounds were assigned, 49 in Tahiti acid lime, 49 in Sicilian lemon, 37 in Persian lime, 34 in Italian tangerine and oval kumquat, 33 in Valencia orange, 32 in Baia orange and round kumquat, 28 in Blood-of-Mombuca orange and 26 in Lima orange. 26 major compounds represented 93-99% of the total chromatogram peak area. Terpenic compounds were predominant in all samples, especially monoterpenes (about 48-97% of the total chromatogram peak area), while lower proportions of aldehydes (0.2-16.1%), monoterpene alcohols (0.4-11.8%) and esters (0.0-7.7%) were observed. Even though a few compounds like limonene, β-myrcene, linalool, α-pinene and valencene were detected in all citrus, volatile compounds followed specific patterns in the different citruses, with a clear distinction among them, especially between lemon flours and the remaining flours. The variety of volatile profiles and singular specific volatolomic signatures in citrus peels can be explored for different applications related to food flavoring and preservation, and promotion of good health. These aspects should be thoroughly investigated in future studies.

Plant-Derived Compounds as Promising Therapeutics for Vitiligo

Vitiligo is the most common depigmenting disorder characterized by white patches in the skin. The pathogenetic origin of vitiligo revolves around autoimmune destruction of melanocytes in which, for instance, oxidative stress is responsible for melanocyte molecular, organelle dysfunction and melanocyte specific antigen exposure as well as melanocyte cell death and thus serves as an important contributor for vitiligo progression. In recent years, natural products have shown a wide range of pharmacological bioactivities against many skin diseases, and this review focuses on the effects and mechanisms of natural compounds against vitiligo models. It is showed that some natural compounds such as flavonoids, phenols, glycosides and coumarins have a protective role in melanocytes and thereby arrest the depigmentation, and, additionally, Nrf2/HO-1, MAPK, JAK/STAT, cAMP/PKA, and Wnt/β-catenin signaling pathways were reported to be implicated in these protective effects. This review discusses the great potential of plant derived natural products as anti-vitiligo agents, as well as the future directions to explore.

Rapid Discrimination of Citrus reticulata 'Chachi' by Electrospray Ionization-Ion Mobility-High-Resolution Mass Spectrometry

A common idea is that some dishonest businessmen often disguise Citrus reticulata Blanco varieties as Citrus reticulata 'Chachi', which places consumers at risk of economic losses. In this work, we combined high-resolution ion mobility (U-shaped mobility analyzer) with high-resolution mass spectrometry to rapidly distinguish Citrus reticulata 'Chachi' from other Citrus species. The samples were analyzed directly through simple extraction and the analytes were separated in one second. It only took about 1 min to perform a cycle of sample analysis and data acquisition. The results showed that polymethoxylated flavones and their isomers were separated easily by the ion mobility analyzer and preliminarily identified according to the accurate mass. Moreover, the collision cross-section values of all analytes, which could be used as auxiliary parameters to characterize and identify the compounds in the samples, were measured. Twenty-four samples were grouped as two clusters by multivariate analysis, which meant that Citrus reticulata 'Chachi' could be effectively differentiated. It was confirmed that the developed method had the potential to rapidly separate polymethoxylated flavones and distinguish between Citrus reticulata 'Chachi' and other Citrus reticulata Blanco varieties.

Development of Electrochemical Sensors/Biosensors to Detect Natural and Synthetic Compounds Related to Agroalimentary, Environmental and Health Systems in Argentina. A Review of the Last Decade

Electrochemical sensors and biosensors are analytical tools, which are in continuous development with the aim of generating new analytical devices which are more reliable, cheaper, faster, sensitive, selective, and robust than others. In matrices related to agroalimentary, environmental, or health systems, natural or synthetic compounds occur which fulfil specific roles; some of them (such as mycotoxins or herbicides) may possess harmful properties, and others (such as antioxidants) beneficial ones. This imposes a challenge to develop new tools and analytical methodologies for their detection and quantification. This review summarises different aspects related to the development of electrochemical sensors and biosensors carried out in Argentina in the last ten years for application in agroalimentary, environmental, and health fields. The discussion focuses on the construction and development of electroanalytical methodologies for the determination of mycotoxins, herbicides, and natural and synthetic antioxidants. Studies based on the use of different electrode materials modified with micro/nanostructures, functional groups, and biomolecules, complemented by the use of chemometric tools, are explored. Results of the latest reports from research groups in Argentina are presented. The main goals are highlighted.

Structural and Emulsifying Properties of Citric Acid Extracted Satsuma Mandarin Peel Pectin

Satsuma mandarin peel pectin (MPP) was extracted by citric acid and its structure and emulsifying ability were evaluated. Structural characterization, including NMR, FTIR, monosaccharide compositions demonstrated that MMP showed lower DM value and higher Mw than commercial citrus pectin (CCP). In addition, MPP exhibited significantly better emulsification performance than CCP. When MPP concentration was increased to 1%, 1.5% (10 g/L, 15 g/L) and the pH was 3 (acidic condition), a stable emulsion containing 10% oil fraction could be obtained. The particle size of the obtained emulsion was ranging from 1.0–2.3 μm, its emulsifying activity ranged from 93–100% and emulsifying stability was 94–100%. Besides, MPP can better ensure the storage stability of higher oil ratio emulsions. The results demonstrated that the stable emulsifying properties of MPP may largely depend on the lower DM value and higher Mw. MPP could be used as a novel polysaccharide emulsifier, especially under acidic conditions, providing a promising alternative for natural emulsifiers that could be used in the food industry.

Essential Oils of Melaleuca, Citrus, Cupressus, and Litsea for the Management of Infections Caused by Candida Species: A Systematic Review

Candida is a common agent of infection in humans, which has a wide distribution and is a colonizer fungus of the body, occasionally assuming the role of a pathogen. The type of treatment depends on the site of infection and the clinical condition of the patient. Superficial infections, such as mucosal infections, can be treated with topical medications. So-called alternative therapies have rarely been studied, although the literature records the effectiveness of some treatments, especially as complementary therapy. The aims of this review were to analyze evidence of the anti-Candida inhibitory activity of essential oils of the Citrus, Cupressus, Litsea, and Melaleuca species; in addition to addressing the chemical composition, probable mechanisms of antifungal action and studies of toxicity, cytotoxicity, and genotoxicity were included. The literature from Medline/PubMed, Science Direct, Scopus, Web of Science, and the Brazilian database Periodic Capes was reviewed. Thirty-eight articles were selected, which included two articles on Litsea spp., seven on Cupressus spp., thirteen articles on Citrus spp., and twenty-one articles on Melaleuca spp. In conclusion, this study showed in vitro evidence for the use of essential oils of the plant species evaluated for the treatment of infections caused by different Candida species.

Pressurized Extraction as an Opportunity to Recover Antioxidants from Orange Peels: Heat treatment and Nanoemulsion Design for Modulating Oxidative Stress

Orange peel by-products generated in the food industry are an important source of value-added compounds that can be potentially reused. In the current research, the effect of oven-drying (50–70 °C) and freeze-drying on the bioactive compounds and antioxidant potential from Navelina, Salustriana, and Sanguina peel waste was investigated using pressurized extraction (ASE). Sixty volatile components were identified by ASE-GC-MS. The levels of terpene derivatives (sesquitenenes, alcohols, aldehydes, hydrocarbons, and esters) remained practically unaffected among fresh and freeze-dried orange peels, whereas drying at 70 °C caused significative decreases in Navelina, Salustriana, and Sanguina peels. Hesperidin and narirutin were the main flavonoids quantified by HPLC-MS. Freeze-dried Sanguina peels showed the highest levels of total-polyphenols (113.3 mg GAE·g⁻¹), total flavonoids (39.0 mg QE·g⁻¹), outstanding values of hesperedin (187.6 µg·g⁻¹), phenol acids (16.54 mg·g⁻¹ DW), and the greatest antioxidant values (DPPH•, FRAP, and ABTS^•+ assays) in comparison with oven-dried samples and the other varieties. Nanotechnology approaches allowed the formulation of antioxidant-loaded nanoemulsions, stabilized with lecithin, starting from orange peel extracts. Those provided 70–80% of protection against oxidative UV-radiation, also decreasing the ROS levels into the Caco-2 cells. Overall, pressurized extracts from freeze-drying orange peel can be considered a good source of natural antioxidants that could be exploited in food applications for the development of new products of commercial interest.

Green Extraction of Bioactive Compounds from Plant Biomass and Their Application in Meat as Natural Antioxidant

Plant extracts are rich in various bioactive compounds exerting antioxidants effects, such as phenolics, catechins, flavonoids, quercetin, anthocyanin, tocopherol, rutin, chlorogenic acid, lycopene, caffeic acid, ferulic acid, p-coumaric acid, vitamin C, protocatechuic acid, vitamin E, carotenoids, β-carotene, myricetin, kaempferol, carnosine, zeaxanthin, sesamol, rosmarinic acid, carnosic acid, and carnosol. The extraction processing protocols such as solvent, time, temperature, and plant powder should be optimized to obtain the optimum yield with the maximum concentration of active ingredients. The application of novel green extraction technologies has improved extraction yields with a high concentration of active compounds, heat-labile compounds at a lower environmental cost, in a short duration, and with efficient utilization of the solvent. The application of various combinations of extraction technologies has proved to exert a synergistic effect or to act as an adjunct. There is a need for proper identification, segregation, and purification of the active ingredients in plant extracts for their efficient utilization in the meat industry, as natural antioxidants. The present review has critically analyzed the conventional and green extraction technologies in extracting bioactive compounds from plant biomass and their utilization in meat as natural antioxidants.

The Lipid-Modulating Effect of Tangeretin on the Inhibition of Angiopoietin-like 3 (ANGPTL3) Gene Expression through Regulation of LXRα Activation in Hepatic Cells

The excessive accumulation of TG-rich lipoproteins (TGRLs) in plasma is associated with dyslipidemia and atherosclerotic cardiovascular diseases (ASCVDs). Tangeretin is a bioactive pentamethoxyflavone mainly found in citrus peels, and it has been reported to protect against hyperlipidemia, diabetes, and obesity. The aim of this study was to investigate the lipid-modulating effects and the underlying mechanisms of tangeretin action in hepatic cells. Transcriptome and bioinformatics analyses with the Gene Ontology (GO) database showed that tangeretin significantly regulated a set of 13 differentially expressed genes (DEGs) associated with the regulation of lipoprotein lipase (LPL) activity. Among these DEGs, angiopoietin-like 3 (ANGPTL3), an essential inhibitor of LPL catalytic activity that regulates TGRL metabolism in plasma, was markedly downregulated by tangeretin. We demonstrated that tangeretin significantly inhibited the mRNA expression of ANGPTL3 in HepG2 and Huh-7 cells. Tangeretin treatment of hepatic cells also reduced the levels of both intracellular and secreted ANGPTL3 proteins. Moreover, we found that inhibition of ANGPTL3 production by tangeretin augmented LPL activity. We further demonstrated that the transcriptional activity of the ANGPTL3 promoter was significantly attenuated by tangeretin, and we identified a DNA element located between the −250 and −121 positions that responded to tangeretin. Furthermore, we found that tangeretin did not alter the levels of the nuclear liver X receptor α (LXRα) protein, an essential transcription factor that binds to the tangeretin-responsive element, but it can counteract LXRα-mediated ANGPTL3 transcription. On the basis of molecular docking analysis, tangeretin was predicted to bind to the ligand-binding domain of LXRα, which would result in suppression of LXRα activation. Our findings support the hypothesis that tangeretin exerts a lipid-lowering effect by modulating the LXRα-ANGPTL3-LPL pathway, and thus, it can be used as a potential phytochemical for the prevention or treatment of dyslipidemia.

Hesperidin prevents the combined toxicity of decabromodiphenyl ether and sodium nitrite in vitro

Decabromodiphenyl ether (BDE-209) and Sodium nitrite (SN) coexist in the processing meat and fish foods, but there is no research considering them together. The present study aimed to investigate the binary mixture's toxicity of BDE-209 and SN and explore the protective effect of hesperidin (Hsp) on the combined toxicity. Results showed that compared with the impact of BDE-209 or SN alone, the binary mixture had a synergistic toxic effect on impairing the viability of HepG2 cells, accompanied by oxidative stress, Ca²⁺ accumulation, mitochondrial dysfunction. The increase of γ-H2AX fluorescent foci and micronuclei number also indicated its genotoxicity. Pretreatment of Hsp could significantly alleviate the above damage caused by the binary combination. These findings revealed the toxicological interaction of BDE-209 and SN and highlighted that food containing abundant natural flavonoids, as hesperidin, could reduce this toxicological risk.

Valorization of Citrus Co-Products: Recovery of Bioactive Compounds and Application in Meat and Meat Products

Citrus fruits (orange, lemon, mandarin, and grapefruit) are one of the most extensively cultivated crops. Actually, fresh consumption far exceeds the demand and, subsequently, a great volume of the production is destined for the citrus-processing industries, which produce a huge quantity of co-products. These co-products, without proper treatment and disposal, might cause severe environmental problems. The co-products obtained from the citrus industry may be considered a very important source of high-added-value bioactive compounds that could be used in the pharmaceutical, cosmetic, and dietetic industries, and mainly in the food industry. Due to consumer demands, the food industry is exploring a new and economical source of bioactive compounds to develop novel foods with healthy properties. Thus, the aim of this review is to describe the possible benefits of citrus co-products as a source of bioactive compounds and their applications in the development of healthier meat and meat products.

Antioxidant and antimicrobial activities and UPLC-ESI-MS/MS polyphenolic profile of sweet orange peel extracts

With growing consumer awareness, exploitation of renewable resources is cost-effective and environment friendly. This work examines the potential of citrus peels as natural antioxidants and antimicrobials for food preservation. Extraction yield, total soluble phenols and flavonoids of various citrus peels (sweet orange, lemon, tangerine and grapefruit) were optimized by varying the solvent type. While the highest extract yield (~16 ​g/100g) was obtained from the sweet orange peels in methanol, extraction with ethanol maximized the concentration of total phenols and flavonoids (~80 ​mg catechol equivalents/100 ​g dry weight). In addition, sweet orange peel extract showed the highest DPPH, ABTS and hydroxyl radical scavenging values. UPLC-ESI-MS/MS analysis of aqueous and ethanolic extracts of sweet orange peels revealed more than 40 polyphenolic compounds including phenolic acids and flavonoids, some of which have not been previously reported. The predominant polyphenols were narirutin, naringin, hesperetin-7-O-rutinoside naringenin, quinic acid, hesperetin, datiscetin-3-O-rutinoside and sakuranetin. The incorporation of sweet orange peel extract into two vegetable oils enhanced their oxidative stability. In addition, all citrus peel extracts possessed high antimicrobial activity against several food-borne pathogens, and the activity was highest for the sweet orange peel extract. Overall results suggested the great potential of sweet orange peels as natural antioxidant and antimicrobials, which can be efficiently extracted using a simple and low-cost method, for enhancing the storage stability and safety of vegetable oils.

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Citrus peels extracts exhibited high contents of polyphenols and flavonoids with high antioxidant and antimicrobial capacities.

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Sweet orange peel extracts in ethanol and water showed high yield of polyphenols and flavonoids.

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The polyphenolic compounds (~40) in sweet orange peel extracts were identified and quantified by UPLC-ESI-MS/MS.

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Supplementing orange peel extract into edible oils prevented rancidity.

Lemon Oils Attenuate the Pathogenicity of Pseudomonas aeruginosa by Quorum Sensing Inhibition

The chemical composition of three Citrus limon oils: lemon essential oil (LEO), lemon terpenes (LT) and lemon essence (LE), and their influence in the virulence factors production and motility (swarming and swimming) of two Pseudomonas aeruginosa strains (ATCC 27853 and a multidrug-resistant HT5) were investigated. The main compound, limonene, was also tested in biological assays. Eighty-four compounds, accounting for a relative peak area of 99.23%, 98.58% and 99.64%, were identified by GC/MS. Limonene (59-60%), γ-terpinene (10-11%) and β-pinene (7-15%) were the main compounds. All lemon oils inhibited specific biofilm production and bacterial metabolic activities into biofilm in a dose-dependent manner (20-65%, in the range of 0.1-4 mg mL^-1) of both strains. Besides, all samples inhibited about 50% of the elastase activity at 0.1 mg mL^-1. Pyocyanin biosynthesis decreases until 64% (0.1-4 mg mL^-1) for both strains. Swarming motility of P. aeruginosa ATCC 27853 was completely inhibited by 2 mg mL^-1 of lemon oils. Furthermore, a decrease (29-55%, 0.1-4 mg mL^-1) in the synthesis of Quorum sensing (QS) signals was observed. The oils showed higher biological activities than limonene. Hence, their ability to control the biofilm of P. aeruginosa and reduce the production of virulence factors regulated by QS makes lemon oils good candidates to be applied as preservatives in the food processing industry.

Antioxidant Activity and Healthy Benefits of Natural Pigments in Fruits: A Review

Natural pigments, including carotenoids, flavonoids and anthocyanidins, determine the attractive color of fruits. These natural pigments are essential secondary metabolites, which play multiple roles in the whole life cycle of plants and are characterized by powerful antioxidant activity. After decades of research and development, multiple benefits of these natural pigments to human health have been explored and recognized and have shown bright application prospects in food, medicine, cosmetics and other industries. In this paper, the research progress of natural fruit pigments in recent years was reviewed, including the structural characteristics and classification, distribution in fruits and analysis methods, biosynthetic process, antioxidant capacity and mechanism, bioaccessibility and bioavailability, and health benefits. Overall, this paper summarizes the recent advances in antioxidant activity and other biological functions of natural fruit pigments, which aims to provide guidance for future research.

Variations in phenolic acids and antioxidant activity of navel orange at different growth stages

Ripe navel orange has abundant amounts of phenolic compounds. Few studies monitored changes in these compounds during ripening. In this study, the effects of navel orange maturation on dynamic changes in antioxidant activity, total phenolic content (TPC), total flavonoid content (TFC) and phenolic acids were investigated. Five growth stages of navel orange were studied, and nine phenolic acids were detected via high performance liquid chromatography-triple quadrupole mass spectrometry (HPLC-QQQ-MS). Results showed that antioxidant activity, TFC and TPC decreased gradually with fruit ripening. The concentrations of most phenolic acids also declined during fruit maturation, except for free fractions of sinapic acid and bound fractions of ferulic and caffeic acids. Ferulic acid was the most dominant of all phenolic acids at all growth stages. Partial least-squares showed significant differences among fruits of different maturities. A significant correlation between antioxidant capacity, TPC, TFC and some phenolic acids was found.

Bread Fortified with Cooked Purple Potato Flour and Citrus Albedo: An Evaluation of Its Compositional and Sensorial Properties

This research aimed to explore the feasibility of fortifying bread with cooked Vitelotte potato powder and Citrus albedo, comparing the use of baker's yeast or sourdough as leavening agents. Breads obtained were thus subjected to physico-chemical and sensory characterizations. The replacement of part of the wheat flour with purple potato and albedo determined a significant enhancement of the phenolic profile and antioxidant status of fortified breads, as well as a longer shelf life. Thanks to its acidity and antimicrobial activity, sourdough improved the levels of health-promoting compounds and stability. Both the fortification and the leavening agent deeply affected the organoleptic, expression, and the aroma profile, of the fortified bread. Interestingly, albedo addition, despite its effectiveness in boosting the phenolic profile, determined a higher perception of aftertaste and bitterness, irrespective of the leavening agent. Based on these results, the use of purple potatoes and Citrus albedo, if properly formulated, could represent a valuable strategy for the development of high-quality products, with longer shelf-life.

Nanonutraceuticals: The New Frontier of Supplementary Food

In the last few decades, the combination between nanotechnology and nutraceutics has gained the attention of several research groups. Nutraceuticals are considered as active compounds, abundant in natural products, showing beneficial effects on human health. Unfortunately, the uses, and consequently the health benefits, of many nutraceutical products are limited by their unsuitable chemico-physical features. For example, many nutraceuticals are characterized by low water solubility, low stability and high susceptibility to light and oxygen, poor absorption and potential chemical modifications after their administration. Based on the potential efficacy of nutraceuticals and on their limiting features, nanotechnology could be considered a revolutionary innovation in empowering the beneficial properties of nutraceuticals on human health, thus enhancing their efficacy in several diseases. For this reason, nanotechnology could represent a new frontier in supplementary food. In this review, the most recent nanotechnological approaches are discussed, focusing on their ability to improve the bioavailability of the most common nutraceuticals, providing an overview regarding both the advantages and the possible limitations of the use of several nanodelivery systems. In fact, although the efficacy of smart nanocarriers in improving health benefits deriving from nutraceuticals has been widely demonstrated, the conflicting opinions on the mechanism of action of some nanosystems still reduce their applicability in the therapeutic field.

Antioxidant/pro-oxidant and antiproliferative activities of phenolic-rich foods and extracts: A cell-based point of view

Phenolic compounds have demonstrated several in vitro beneficial properties by acting as antioxidant and pro-oxidant agents. This chapter approaches the relationship among oxidative stress, cancer, phenolic compounds and antiproliferative activity. Moreover, it discusses in vitro techniques and their biological applications, regarding cell viability and intracellular measure of reactive oxygen assays. The in vitro methods are important tools for screening and understanding the pathways involved on antiproliferative and antioxidant/pro-oxidant effects of phenolic compounds. These findings open avenues for the development of innovative food, chemical structures, technological applications and future perspectives in this research field.

Development of astaxanthin production from citrus peel extract using Xanthophyllomyces dendrorhous

Developing a use for the inedible parts of citrus, mainly peel, would have great environmental and economic benefits worldwide. Astaxanthin is a value-added fine chemical that affects fish pigmentation and has recently been used in healthcare products for humans, resulting in an increased demand. This study aimed to produce astaxanthin from a citrus, ponkan, peel extract using the yeast Xanthophyllomyces dendrorhous, which has the ability to use both pentose and hexose. Feeding on only ponkan peel extract enhanced X. dendrorhous growth and the concomitant astaxanthin production. Additionally, we determined that pectin and its arabinose content were the main substrate and sole carbon source, respectively, for X. dendrorhous growth and astaxanthin production. Thus, ponkan peel extract could become a valuable resource for X. dendrorhous-based astaxanthin production. Using citrus peel extract for microbial fermentation will allow the development of processes that produce value-added chemicals from agricultural byproducts.

Influence of Citrus Flavor Addition in Brewing Process: Characterization of the Volatile and Non-Volatile Profile to Prevent Frauds and Adulterations

In the last few years, the flavored beer market has increased significantly. In particular, consumers showed a growing interest in citrus-flavored beers. Citrus fruits contain, among other class of compounds, terpenes and terpenoids and oxygenated heterocyclic compounds. The absence of a specific legislation concerning beer flavored production and ingredients reported on the labels makes these beers subject to possible adulterations. Solid phase micro extraction (SPME) followed by gas chromatographic–mass spectrometry (GC-MS) and gas chromatographic-flame ionization detector (GC-FID) analysis of the volatile profile together with the characterization of the oxygen heterocyclic compounds through high performance liquid chromatography coupled to tandem mass spectrometry (HPLC-MS/MS) demonstrated to be a powerful analytical strategy for quality control. In this study, we combined the volatile and non-volatile profiles of “citrus flavored mainstream beers”, in order to evaluate the authenticity and determine markers to prevent food frauds. The changes in the aroma composition of the unflavored types after the addition of peel, or citrus essential oil were also evaluated. The linear retention index (LRI) system was used for both techniques; in particular, its application in liquid chromatography is still limited and represents a novelty. The coupling of the high sensitivity of the HPLC MS/MS method with the LRI system, it has made possible for the first time a reliable identification and an accurate quantification of furocoumarins in citrus-flavored beers.

Plant Secondary Metabolites: An Opportunity for Circular Economy

Moving toward a more sustainable development, a pivotal role is played by circular economy and a smarter waste management. Industrial wastes from plants offer a wide spectrum of possibilities for their valorization, still being enriched in high added-value molecules, such as secondary metabolites (SMs). The current review provides an overview of the most common SM classes (chemical structures, classification, biological activities) present in different plant waste/by-products and their potential use in various fields. A bibliographic survey was carried out, taking into account 99 research articles (from 2006 to 2020), summarizing all the information about waste type, its plant source, industrial sector of provenience, contained SMs, reported bioactivities, and proposals for its valorization. This survey highlighted that a great deal of the current publications are focused on the exploitation of plant wastes in human healthcare and food (including cosmetic, pharmaceutical, nutraceutical and food additives). However, as summarized in this review, plant SMs also possess an enormous potential for further uses. Accordingly, an increasing number of investigations on neglected plant matrices and their use in areas such as veterinary science or agriculture are expected, considering also the need to implement "greener" practices in the latter sector.

Potential compounds from several Indonesian plants to prevent SARS-CoV-2 infection: A mini-review of SARS-CoV-2 therapeutic targets

The outbreak of coronaviruses (CoVs) presents an enormous threat to humans. To date, no new therapeutic drugs or vaccines licensed to treat human coronaviruses remain undiscovered. This mini-review briefly reports the number of potential plants widely distributed in Indonesia for further research and development as anti-SARS-CoV-2 agents and the critical targets for SARS-CoV-2 therapy, such as angiotensin-converting enzyme 2 (ACE-2) receptor, spike protein, 3-chymotrypsin-like protease (3CL^pro), papain-like protease (PL^pro), RNA-dependent RNA polymerase (RdRp), helicase, and serine protease. Indonesia is rich in medicinal plants (herbal); it also has a long history of using plants to treat various hereditary diseases. However, since SARS-CoV-2 is a new disease, it has no history of plant-based treatment anywhere in the world. This mini-review describes natural products from several Indonesian plants that contain compounds that could potentially prevent or reduce SARS-CoV-2 infection, act as potential targeted therapy, and provide new therapeutic strategies to develop SARS-CoV-2 countermeasures.

β-Selective Glycosylation Using Axial-Rich and 2-O-Rhamnosylated Glucosyl Donors Controlled by the Protecting Pattern of the Second Sugar

Herein, we describe two counterexamples of the previously reported β/α-selectivity of 96/4 for glycosylation using ethyl 2-O-[2,3,4-tris-O-tert-butyldimethylsilyl (TBS)-α-L-rhamnopyranosyl]-3,4,6-tris-O-TBS-thio-β-D-glucopyranoside as the glycosyl donor. Furthermore, we investigated the effects of protecting group on the rhamnose moieties in the glycosylation with cholestanol and revealed that β-selectivity originated from the two TBS groups at the 3-O and 4-O positions of rhamnose. In contrast, the TBS group at the 2-O position of rhamnose hampered the β-selectivity. Finally, the β/α-selectivity during the glycosylation was enhanced to ≥99/1. The results obtained herein suggest that the protecting groups on the sugar connected to the 2-O of a glycosyl donor with axial-rich conformation can control the stereoselectivity of glycosylation.