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1.
Nitric Oxide ; 103: 29-30, 2020 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-32712272

RESUMO

Most outcomes of COVID-19 are associated with dysfunction of the vascular system, particularly in the lung. Inhalation of nitric oxide (NO) gas is currently being investigated as a treatment for patients with moderate to severe COVID-19. In addition to the expected vasodilation effect, it has been also suggested that NO potentially prevents infection by SARS-CoV-2. Since NO is an unstable radical molecule that is easily oxidized by multiple mechanisms in the human body, it is practically difficult to control its concentration at lesions that need NO. Inorganic nitrate and/or nitrite are known as precursors of NO that can be produced through chemical as well enzymatic reduction. It appears that this NO synthase (NOS)-independent mechanism has been overlooked in the current developing of clinical treatments. Here, I suggest the missing link between nitrate and COVID-19 in terms of hypoxic NO generation.


Assuntos
Betacoronavirus/efeitos dos fármacos , Infecções por Coronavirus/tratamento farmacológico , Nitratos/metabolismo , Óxido Nítrico/metabolismo , Nitritos/metabolismo , Pneumonia Viral/tratamento farmacológico , Antivirais/metabolismo , Ácido Ascórbico/química , Ácido Ascórbico/uso terapêutico , Infecções por Coronavirus/metabolismo , Infecções por Coronavirus/prevenção & controle , Fatores Relaxantes Dependentes do Endotélio/metabolismo , Humanos , Nitratos/sangue , Nitritos/sangue , Nitritos/química , Pandemias/prevenção & controle , Pneumonia Viral/metabolismo , Pneumonia Viral/prevenção & controle , Vasodilatação/efeitos dos fármacos
2.
J Vis Exp ; (160)2020 06 30.
Artigo em Inglês | MEDLINE | ID: mdl-32716366

RESUMO

Vitamins, especially vitamin C, are important micronutrients found in fruits and vegetables. Vitamin C is also a major contributor to their antioxidant capacity. Lettuce is one of the most popular vegetables among consumers worldwide. An accurate protocol to measure vitamin C content in lettuce and other related species is crucial. We describe here a method using the ultra-high-performance liquid chromatography-ultraviolet (UPLC-UV) technique, in which sample preparation, vitamin extraction and chromatography conditions were optimized. Samples were collected to represent the entire plant, frozen at -80 °C and lyophilized to prevent undesirable oxidation and make their manipulation easier. The extraction of vitamin C was carried out in acidic media, which also contributed to its stability. As vitamin C can be present in two different interconvertible forms, ascorbic acid (AA) and dehydroascorbic acid (DHAA), both compounds should be measured for accurate quantification. The DHAA was quantified indirectly after its reduction to AA because AA shows a higher absorptivity than DHAA in the UV range of the spectrum. From the same extract, two measurements were carried out, one before and one after that reduction reaction. In the first case, we were quantifying the AA content, and in the second one, we quantified the sum of AA and DHAA (TAA: total ascorbic acid) in the form of AA. Then, DHAA quantity was indirectly obtained by subtracting AA coming from the first measurement from TAA. They were determined by UPLC-UV, using a commercial AA standard to build a calibration curve and optimizing the chromatographic procedure, to obtain AA peaks that were completely resolved in a short time. This protocol could be easily extrapolated to any other plant material with slight or no changes. Its accuracy revealed statistically significant differences otherwise unperceived. Other strengths and limitations are discussed more in depth in the manuscript.


Assuntos
Ácido Ascórbico/química , Cromatografia Líquida de Alta Pressão/métodos , Alface/química , Ácido Ascórbico/análise
3.
PLoS One ; 15(7): e0235407, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32649670

RESUMO

Fast scan cyclic voltammetry (FSCV) allows for real -time analysis of phasic neurotransmitter levels. Tryptophan (TRP) is an aromatic amino acid responsible for facilitating electron transfer kinetics in oxidoreductase enzymes. Previous work with TRP-modified electrodes showed increased sensitivity for cyclic voltammetry detection of dopamine (DA) when used with slower scan rates (0.05 V/s). Here, we outline an in vitro proof of concept for TRP-modified electrodes in FSCV detection of DA, and decreased sensitivity for ascorbic acid (AA). TRP-modified electrodes had a limit of detection (LOD) for DA of 2.480 ± 0.343 nM compared to 8.348 ± 0.405 nM for an uncoated electrode. Selectivity for DA/ascorbic acid (AA) was 1.107 ± 0.3643 for uncoated and 15.57 ± 4.184 for TRP-modified electrodes. Additionally, these TRP-modified electrodes demonstrated reproducibility when exposed to extended cycling. TRP-modified electrodes will provide an effective modification to increase sensitivity for DA.


Assuntos
Técnicas Biossensoriais , Dopamina/isolamento & purificação , Técnicas Eletroquímicas , Ácido Ascórbico/química , Carbono/química , Dopamina/química , Eletrodos , Cinética , Triptofano/química , Ácido Úrico/química
4.
Food Chem ; 330: 127166, 2020 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-32535312

RESUMO

Knowing the bioaccessibility of vitamin C in foodstuffs produced for infants and young children is necessary to determine their daily vitamin C intake. The purpose of the present study was to investigate the bioaccessibility of vitamin C in fruit-, vegetable-, and cereal-based baby foodstuffs by an in vitro digestion model at varying gastric pHs. The concentrations of measured vitamin C were higher than the declared amounts on their label. The bioaccessibility of vitamin C ranged from 10.4 to 43.4%, and from 0.4 to 19.2% in fruit- and vegetable-based baby foodstuffs (declared vitamin C fortified) at gastric pH 1.5 and 4, respectively. For cereal-based baby foodstuffs, the bioaccessibility ranged from 1.3 to 53.8%, and from 0.3 to 26.3% at gastric pH 1.5 and 4, respectively. As revealed in this research, the bioaccessibility of vitamin C in baby foodstuffs is very low in both gastric pH conditions.


Assuntos
Ácido Ascórbico/química , Grão Comestível/metabolismo , Frutas/metabolismo , Alimentos Infantis/análise , Verduras/metabolismo , Vitaminas/química , Animais , Grão Comestível/química , Frutas/química , Verduras/química
5.
Food Chem ; 329: 127042, 2020 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-32504916

RESUMO

Polysaccharides are a major active component of Porphyra haitanensis, which is an important food source in many countries. Four different molecular-weight fractions, namely PHPD-I (329 kDa), PHPD-II (203 kDa), PHPD-III (128 kDa), and PHPD-IV (10 kDa), were obtained from P. haitanensis polysaccharides by degradation using the H2O2/ascorbic acid system. PHPD-IV elicited the highest level of antioxidant and immunostimulatory activity among the four fractions. PHPD-IV was purified by DEAE-cellulose column and five fractions were obtained, designated PHPD-IV-1-PHPD-IV-5. PHPD-IV-4 displayed the greatest biological activity by up-regulating the phosphorylation of MAPK signalling molecules. PHPD-IV-4 was further purified, and its structure was characterized by monosaccharide composition and 1/2D-NMR analysis. The result revealed that PHPD-IV-4 was repeated units of â†’ 3) ß-d-galactose (1 â†’ 4) 3, 6-anhydro-α-l-galactose (1→, and â†’ 3) ß-d-galactose (1 â†’ 4) α-l-galactose-6-S (1→. This study provides a theoretical basis for the utilisation and structure-activity assessment of P. haitanensis polysaccharides.


Assuntos
Polissacarídeos/química , Porphyra/química , Antioxidantes/química , Ácido Ascórbico/química , Galactose/química , Peróxido de Hidrogênio/química , Espectroscopia de Ressonância Magnética , Peso Molecular
6.
Arch Biochem Biophys ; 687: 108391, 2020 07 15.
Artigo em Inglês | MEDLINE | ID: mdl-32360749

RESUMO

Hydropersulfides are reported to be good biological reductants, superior to thiols and akin to selenols. As such, they have been previously shown to reduce metalloproteins such as ferric myoglobin and ferric cytochrome c to their ferrous forms under conditions where little or no reduction from corresponding thiols is observed. Not surprisingly, the reduction of ferric myoglobin to ferrous myoglobin under aerobic conditions results in the generation of oxymyoglobin (dioxygen bound ferrous myoglobin). Previous studies have demonstrated that oxymyoglobin can also act as an oxidant with highly reducing species such as hydroxylamine and ascorbate. Considering the reducing properties of hydropersulfides, it is possible that they can also react with oxymyoglobin similarly to hydroxylamine or ascorbate. Herein, this reaction is examined and indeed hydropersulfides are found to react with oxymyoglobin similarly to other reducing species leading to a fleeting ferric myoglobin which is rapidly reduced to the ferrous form also by hydropersulfide.


Assuntos
Mioglobina/química , Sulfetos/química , Animais , Ácido Ascórbico/química , Bovinos , Cavalos , Hidroxilamina/química , Modelos Químicos , Oxirredução , Oxigênio/química , Penicilamina/análogos & derivados
7.
Food Chem ; 324: 126837, 2020 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-32339791

RESUMO

Evidences have shown that phytosome assemblies are novel drug delivery system. However, studies of phytosomes in food applications are scarce. The characteristics of milk phospholipid assemblies and their functionality in terms of in vitro digestibility and bioavailability of encapsulated nutrients (ascorbic acid and α-tocopherol) were studied. The phytosomes were fabricated using ethanolic evaporation technique. Spectral analysis revealed that polar parts of phospholipids formed hydrogen bonds with ascorbic acid hydroxyl groups, further, incorporating ascorbic acid or α-tocopherol into the phospholipid assembly changed the chemical conformation of the complexes. Phospholipid-ascorbic acid phytosomes yielded an optimal complexing index of 98.52 ± 0.03% at a molar ratio of 1:1. Phytosomes exhibited good biocompatibility on intestinal epithelial cells. The cellular uptake of ascorbic acid was 29.06 ± 1.18% for phytosomes. It was higher than that for liposomes (24.14 ± 0.60%) and for ascorbic acid aqueous solution (1.17 ± 0.70%).


Assuntos
Antioxidantes/química , Ácido Ascórbico/química , Lipossomos/química , Leite/química , Fosfolipídeos/química , alfa-Tocoferol/química , Animais , Ácido Ascórbico/farmacocinética , Varredura Diferencial de Calorimetria , Linhagem Celular , Liberação Controlada de Fármacos , Células Epiteliais/efeitos dos fármacos , Ligação de Hidrogênio , Absorção Intestinal/efeitos dos fármacos , Fosfolipídeos/farmacocinética , Ratos , Espectrofotometria Ultravioleta , Espectroscopia de Infravermelho com Transformada de Fourier
8.
Food Chem ; 322: 126754, 2020 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-32283367

RESUMO

During storage of coffee, the key aroma 2-furfurylthiol becomes less active, the mechanisms of this loss and ways to mitigate it were investigated. Aroma profiles were analyzed using GC-MS and sensory properties were evaluated by Quantitative Descriptive Analysis. Quinones, as the oxidation products of hydroxydroquinone, was found to actively bind 2-furfurylthiol, which accounted for the loss of 2-furfurylthiol. To mitigate this loss, ingredients were screened for their ability to prevent 2-furfurylthiol from loss. Cysteine had the highest 2-furfurylthiol releasing efficiency and ascorbic acid was also selected due to its 2-furfurylthiol releasing ability in Fenton reaction system. Concentrations were optimized and the addition of 0.045 g/L cysteine and 0.05 g/L ascorbic acid directly protected aroma during storage, these included 2-furfurylthiol, dimethyltrisulfide, methyl furfuryl disulfide, 4-ethylguaiacol and 4-vinylguaiacol. Ultimately, sensory testing showed a direct enhancement in nutty, sulfurous and roasted aroma attributes, an increase in flavour intensity and preference over shelf life.


Assuntos
Café/química , Furanos/metabolismo , Cromatografia Gasosa-Espectrometria de Massas , Compostos de Sulfidrila/metabolismo , Compostos Orgânicos Voláteis/análise , Ácido Ascórbico/química , Café/metabolismo , Culinária/métodos , Cisteína/química , Armazenamento de Alimentos , Furanos/química , Análise dos Mínimos Quadrados , Quinonas/química , Quinonas/metabolismo , Compostos de Sulfidrila/química , Paladar , Compostos Orgânicos Voláteis/química
9.
Food Chem ; 321: 126744, 2020 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-32278986

RESUMO

This study aimed to evaluate the shelf-life of mechanically filleted well-fed Atlantic mackerel during frozen storage at -25 °C and effect of treatment with antioxidants (sodium erythorbate and a polyphosphate mixture) and different antioxidant application methods (dipping, spraying and glazing). Both physicochemical measurements and sensory analysis were applied. Antioxidant treatments prolonged shelf-life of mackerel. Sensory analysis indicated that untreated fillets had a shelf-life of less than 2.5 months, while all antioxidant treated fillets exceeded that. The most effective treatment, dipping fillets into a sodium erythorbate solution, yielding a shelf-life of 15 months. Physicochemical methods used to evaluate degradation of lipids in the fillets were free fatty acids (FFA), lipid hydroperoxides (PV) and thiobarbituric acid reactive substances (TBARS). They did not correlate with sensory results and might therefore be a questionable choice for evaluation of oxidation and development of rancid flavour and odour in complex matrixes such as Atlantic mackerel.


Assuntos
Antioxidantes/química , Produtos Pesqueiros , Armazenamento de Alimentos/métodos , Perciformes , Paladar , Animais , Ácido Ascórbico/química , Ácidos Graxos/análise , Produtos Pesqueiros/análise , Congelamento , Humanos , Lipídeos/química , Oxirredução , Polifosfatos/química , Substâncias Reativas com Ácido Tiobarbitúrico/química , Fatores de Tempo
10.
Food Chem ; 320: 126653, 2020 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-32217430

RESUMO

Curcumin is claimed to have many health benefits, but it has low chemical stability. In this study, the influence of food-grade antioxidants on the chemical degradation of curcumin-enriched oil-in-water emulsions was examined. The curcumin degradation rate and extent depended on antioxidant type. The water-soluble antioxidants were more effective at protecting curcumin from degradation than the oil-soluble ones, which may have been because curcumin degrades faster in water than in oil. Interestingly, the amphiphilic antioxidant was almost as effective as the water-soluble ones. The oil-soluble antioxidant actually slightly promoted curcumin degradation. In summary, curcumin retention after storage declined in the following order: 82.6% (Trolox) ~82.2% (ascorbic acid) >79.5% (ascorbyl palmitate) ≫57.9% (control) >52.7% (α-tocopherol). The effectiveness of ascorbic acid in stabilizing curcumin increased as its concentration was raised (0-300 µM). Our results may facilitate the creation of curcumin-enriched foods and beverages with enhanced bioactivity.


Assuntos
Antioxidantes/química , Curcumina/química , Emulsões/química , Ácido Ascórbico/análogos & derivados , Ácido Ascórbico/química , Cromanos/química , Óleos/química , Solubilidade , Água/química , alfa-Tocoferol/química
11.
Proc Natl Acad Sci U S A ; 117(12): 6484-6490, 2020 03 24.
Artigo em Inglês | MEDLINE | ID: mdl-32152099

RESUMO

In redox metalloenzymes, the process of electron transfer often involves the concerted movement of a proton. These processes are referred to as proton-coupled electron transfer, and they underpin a wide variety of biological processes, including respiration, energy conversion, photosynthesis, and metalloenzyme catalysis. The mechanisms of proton delivery are incompletely understood, in part due to an absence of information on exact proton locations and hydrogen bonding structures in a bona fide metalloenzyme proton pathway. Here, we present a 2.1-Å neutron crystal structure of the complex formed between a redox metalloenzyme (ascorbate peroxidase) and its reducing substrate (ascorbate). In the neutron structure of the complex, the protonation states of the electron/proton donor (ascorbate) and all of the residues involved in the electron/proton transfer pathway are directly observed. This information sheds light on possible proton movements during heme-catalyzed oxygen activation, as well as on ascorbate oxidation.


Assuntos
Elétrons , Metaloproteínas/química , Prótons , Ascorbato Peroxidases/química , Ascorbato Peroxidases/metabolismo , Ácido Ascórbico/química , Ácido Ascórbico/metabolismo , Catálise , Heme/química , Ligação de Hidrogênio , Metaloproteínas/metabolismo , Modelos Moleculares , Difração de Nêutrons , Oxirredução
12.
Int J Nanomedicine ; 15: 115-124, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32021168

RESUMO

Background: Selenium is an essential trace element that is critical for many biological processes. Selenium nanoparticles (SeNPs) have shown more promise than other forms of selenium due to their low cytotoxicity and high bioavailability. Methods: In this work, a one-step method was demonstrated for fabricating bovine serum albumin (BSA) stabilized SeNPs using ascorbic acid as the reductant. Human dermal fibroblasts were used to assess mammalian cytotoxicity, and Staphylococcus aureus and Escherichia coli were used to assess antibacterial performance. Results: These SeNPs demonstrated increased fibroblast growth and reduced Staphylococcus aureus growth with a fibroblast IC50 value (>681 µg/mL) 1 order of magnitude higher than that for bacteria at day 1. Conclusion: This study demonstrated the promise of this synthesis process in achieving controllable selenium nanoparticle sizes without the use of strong basic solvents for improved antibacterial properties.


Assuntos
Antibacterianos/farmacologia , Nanopartículas/química , Selênio/farmacologia , Antibacterianos/química , Ácido Ascórbico/química , Ciclo Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Células Cultivadas , Escherichia coli/efeitos dos fármacos , Fibroblastos/efeitos dos fármacos , Química Verde , Humanos , Tamanho da Partícula , Selênio/química , Soroalbumina Bovina/química , Staphylococcus aureus/efeitos dos fármacos
13.
Food Chem ; 315: 126275, 2020 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-32004982

RESUMO

The effects of individual epi-brassinolide (eBL) and NaCl, as well as their combination on contents of main phytochemicals and antioxidant capacity of Chinese kale sprouts were investigated. Our results showed that the application of 100 nM eBL decreased the contents of individual and total glucosinolates, while treatments of 160 mM NaCl both alone and combined with 100 nM eBL enhanced the glucosinolates accumulation by promoting the expression of genes involved in glucosinolate biosynthesis in Chinese kale sprouts and the combined treatment led to significantly higher content of most glucosinolate profiles. Moreover, it also elevated the contents of ascorbic acid and total carotenoids, whereas did not influence the total phenolics and antioxidant capacity. These findings indicated that the combined treatment of 100 nM eBL plus 160 mM NaCl could provide a new strategy to improve the main health promoting compounds in Chinese kale sprouts.


Assuntos
Brassica/química , Brassinosteroides/química , Compostos Fitoquímicos/química , Plântula/química , Cloreto de Sódio/química , Esteroides Heterocíclicos/química , Antioxidantes/química , Ácido Ascórbico/química , Carotenoides/química , Glucosinolatos/química , Fenóis/química , Cloreto de Sódio/farmacologia
14.
J Oleo Sci ; 69(2): 93-103, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32023581

RESUMO

In this study, the antioxidative capacity of caffeic acid (CA), ascorbyl palmitate (AP), α-tocopherol (α-TO), and caffeic acid phenethyl ester (CAPE) was evaluated under the thermal oxidation model, in which 200 ppm of each compound was added to soybean oil, followed by thermal oxidation at 180°C for 32 h. Change of viscosity, acid value (AV), conjugated dienoic acid value (CDAV), p-anisidine value (p-AV), total polar materials (TPM), and the ratio of C18:2 to C16:0 (LA/PA) were evaluated during the reaction. All antioxidants showed significantly lower viscosity, TPM, and p-AV, and higher LA/PA, than the control (without antioxidant, CON), indicating that thermal oxidation was delayed. Among them, CAPE showed significantly lower viscosity, TPM, and p-AV, and higher LA/PA, than the other antioxidants (p < 0.05). In the correlation between the oxidation parameters measured from CON and CAPE, the correlation coefficient between p-AV and viscosity was rather low at r = 0.7603 (in CON) and r = 0.7338 (in CAPE), respectively.


Assuntos
Ácido Ascórbico/análogos & derivados , Ácidos Cafeicos/química , Ésteres/química , alfa-Tocoferol/química , Ácido Ascórbico/química , Oxirredução
15.
Food Chem ; 316: 126297, 2020 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-32044703

RESUMO

Strawberry (cv. Senga Sengana) and raspberry (cv. Veten) were processed into jams at 60, 85 or 93 °C and stored at 4 or 23 °C for 8 and 16 weeks. High processing temperature reduced ascorbic acid, total monomeric anthocyanins (TMA) and total phenolics (TP) in strawberries (p<0.05), but not in raspberries. Processing temperature had minor effect on bioactive compounds in the jams during storage (<10% explained variance), but influenced color (L*, °Hue, Chroma), especially L* of the strawberry jams (73.3%). Storage period explained most of the variance in ascorbic acid (>90%), TMA (>42%) and TP (>69%). Storage temperature affected stability of anthocyanins, but had minor effect on ascorbic acid, which declined rapidly independent of storage temperature. Storage temperature also explained most of the variance (>40%) in Chroma of the jams and L* of raspberry jams (53%). Bioactive compounds and color were more stable in raspberry jams than in strawberry jams.


Assuntos
Antocianinas/química , Ácido Ascórbico/química , Alimentos em Conserva/análise , Fragaria/química , Rubus/química , Cor , Frutas , Fenóis , Temperatura
16.
Carbohydr Polym ; 234: 115920, 2020 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-32070539

RESUMO

Vitamin C (VC) is an indispensable nutrient for human health. However, poor chemical stability in gastric environment restricts its full assimilation by intestine. It is important to construct a safe carrier that can protect VC from the gastric fluid and sustainably release it in intestine. Herein, we designed a novel polyelectrolyte complex (PEC) hydrogel through self-assembly of salecan and chitosan. PEC structure formed by electrostatic interactions was confirmed by FT-IR, XRD, XPS and TGA. Their swelling, morphology, rheology, cytocompatibility and biodegradation were well investigated. In particular, VC released in a controlled and pH-dependent manner. The release amount in simulated intestinal fluid (SIF) was significantly higher than simulated gastric fluid (SGF), and can be maintained at high level in blood after 6 h. Release mechanism agreed well with Ritger-Peppas model. The purpose of this study was to develop a smart nutrient delivery platform for targeted release of VC in intestinal condition.


Assuntos
Ácido Ascórbico/química , Ácido Ascórbico/metabolismo , Quitosana/química , Hidrogéis/química , Polieletrólitos/química , beta-Glucanas/química , Células 3T3-L1 , Animais , Sobrevivência Celular , Células Cultivadas , Preparações de Ação Retardada , Liberação Controlada de Fármacos , Hidrogéis/síntese química , Cinética , Masculino , Camundongos , Estrutura Molecular , Tamanho da Partícula , Polieletrólitos/síntese química , Reologia , Propriedades de Superfície
17.
Food Chem ; 313: 126065, 2020 May 30.
Artigo em Inglês | MEDLINE | ID: mdl-31935663

RESUMO

Brassica spp. are excellent sources of bioactive compounds. These vegetables are usually processed in the home, or by catering and food service industries, on the basis of convenience and taste preference. Shelf-life of these seasonal, perishable vegetables can be extended by preservation methods (e.g. freezing and canning), which usually involve blanching. Cooking, blanching, freezing and canning alter the physical and chemical characteristics of Brassica, and only some of the changes are desirable. We have reviewed the results of a large number of studies that assessed the effects of different treatments and storage conditions on various quality parameters in Brassica. These effects are important in relation to nutritional value, health benefits and attractiveness of the vegetables. The findings vary considerably for each bioactive component, depending on the treatments, conditions and matrices. Optimization of processing and storage conditions is, therefore, important to maximize the intake of beneficial compounds contained in Brassica spp.


Assuntos
Brassica/química , Culinária/métodos , Antioxidantes/química , Ácido Ascórbico/química , Brassica/metabolismo , Carotenoides/química , Congelamento , Humanos , Valor Nutritivo , Fenóis/química , Paladar
18.
Food Chem ; 313: 126139, 2020 May 30.
Artigo em Inglês | MEDLINE | ID: mdl-31927203

RESUMO

Based on various antioxidant mechanisms, four kinds of antioxidants including ascorbyl palmitate (AP), vitamin E (VE), phytic acid (PA) and one of the polyphenols (antioxidant of bamboo leaves, tea polyphenol palmitate or tea polyphenols (TP)) were used in combination to improve oxidative stability of docosahexaenoic acid (DHA) algae oil. To achieve the best effect, the formulations and mixture ratios of the antioxidant combinations were optimized. The effects were monitored by peroxide value, thiobarbituric acid-reactive substances, acid value, free radicals, Rancimat induction time and fatty acid composition of DHA algae oil undergoing accelerated storage. Finally, the DHA algae oil containing 80 mg/kg AP, 80 mg/kg VE, 40 mg/kg PA and 80 mg/kg TP had the highest oxidative stability. Furthermore, the shelf life of DHA algae oil containing the optimum composite antioxidant was predicted by using accelerated shelf life testing coupled with Arrhenius model, which was 3.80-fold longer than the control sample.


Assuntos
Antioxidantes/química , Ácidos Docosa-Hexaenoicos/química , Óleos/química , Ácido Ascórbico/análogos & derivados , Ácido Ascórbico/química , Armazenamento de Alimentos , Oxirredução , Folhas de Planta/química , Polifenóis/química , Sasa/química , Chá/química , Substâncias Reativas com Ácido Tiobarbitúrico/química , Vitamina E/química
19.
J Zoo Wildl Med ; 50(4): 861-867, 2020 Jan 09.
Artigo em Inglês | MEDLINE | ID: mdl-31926516

RESUMO

Antioxidants have a crucial role in protecting the body from oxidative stress, which would otherwise result in cellular damage and possibly predispose animals to disease. The antioxidant capacity of koalas (Phascolarctos cinereus) and its association with health or disease status is currently unknown. Ascorbate, a dietary antioxidant, has previously been identified in a few eucalypt species eaten by koalas. This study aimed to determine 1) differences between the antioxidant capacity of healthy and diseased koalas, and 2) concentration of the antioxidant ascorbate in Eucalyptus spp. leaves eaten by koalas. To determine differences in antioxidant capacity of koalas, plasma samples from clinically healthy koalas in Kangaroo Island, South Australia (SA) (n = 23), euthanized koalas with oxalate nephrosis from Mount Lofty Ranges, SA (n = 11), and euthanized koalas with chlamydiosis from Moggill, Queensland (n = 11) were analyzed for the three antioxidants α-tocopherol, ascorbate, and retinol and for two measures of antioxidant capacity, ferric reducing ability of plasma (FRAP), and trolox equivalent antioxidant capacity (TEAC). The thiobarbituric acid reactive substance (TBARS) measured formation of oxidants, and an oxidative stress index (OSI) was calculated by TBARS/(TEAC + FRAP). Ascorbate concentration was measured in dietary eucalypt leaves from Mount Lofty Ranges and Moggill. Results showed that in diseased Mount Lofty Ranges and Moggill koalas, plasma α-tocopherol concentrations were significantly lower, and ascorbate, TBARS, and OSI was significantly higher compared with clinically healthy koalas from Kangaroo Island. Ascorbate was high in eucalypt leaves, particularly young leaves from the Mount Lofty Ranges. This study showed that disease was associated with some measures of poor antioxidant capacity in koalas and also found that ascorbate is high in the dietary eucalypts of koalas.


Assuntos
Antioxidantes/química , Ácido Ascórbico/química , Eucalyptus/química , Phascolarctidae , Folhas de Planta/química , Animais , Austrália
20.
Molecules ; 25(1)2020 Jan 06.
Artigo em Inglês | MEDLINE | ID: mdl-31935857

RESUMO

Polyphenols play an important role in the sensorial and health-promoting properties of fruits and vegetables and display varying structure-dependent stability during processing and shelf-life. The current work aimed to increase the fundamental understanding of the link between the stability of polyphenols as a function of their structure, presence of ascorbic acid and fructose and total antioxidant capacity (TAC), using a multi-component model system. Polyphenol extract, used as the multi-component model system, was obtained from freeze-dried, high polyphenol content strawberry (Fragaria × ananassa 'Nerina') and twenty-one compounds were identified using high-performance liquid chromatography-mass spectrometry (HPLC-MS). The TAC and the first-order degradation kinetics were obtained, linking the polyphenol stability to its chemical structure, with and without the presence of fructose and ascorbic acid. The TAC (measured by oxygen radical absorption capacity (ORAC) and ferric reducing antioxidant potential (FRAP) assays) was not dramatically affected by storage temperatures and formulation, while polyphenol stability was significantly and structure dependently affected by temperature and the presence of ascorbic acid and fructose. Anthocyanins and phenolic acids were more unstable in the presence of ascorbic acid, while flavonol stability was enhanced by its presence. Shelf life study performed at 37 °C revealed significantly higher stability of purified polyphenols vs. the stability of the same polyphenols in the strawberry extract (multi-component system).


Assuntos
Antioxidantes/química , Antioxidantes/farmacologia , Ácido Ascórbico/química , Frutose/química , Polifenóis/química , Polifenóis/farmacologia , Antioxidantes/isolamento & purificação , Cromatografia Líquida de Alta Pressão , Estabilidade de Medicamentos , Fragaria/química , Frutas/química , Fenóis/análise , Fenóis/química , Compostos Fitoquímicos/análise , Compostos Fitoquímicos/química , Polifenóis/isolamento & purificação , Temperatura
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