Sardine Protein Research Articles

Evaluation of handling and storage stability of spray dried protein hydrolysates from sardine (Sardina pilchardus) processing by-products: Effect of enzymatic hydrolysis time, spray drying temperature and maltodextrin concentration

The effect of processing conditions on handling and storage stability of spray dried sardine protein hydrolysates (SPH) was determined based on equilibrium moisture content (Xe), glass transition temperature (Tg) and surface morphology. SPH with a degree of hydrolysis (DH) of 38.7% and 76.4%, and 0%, 15% and 30% (w/w dry solids) maltodextrin concentration were spray dried at an inlet air temperature of 180 °C and 220 °C and then stored under controlled atmospheric water activity (aw) ranging from 0.113 to 0.843 for a period of 21 days. The powders had high equilibrium moisture content (0.393 – 0.715 g H2O/g dry powder) at 0.843 aw, with high DH producing powders with high Xe (>0.645 g H2O/g dry powder). DH also had a strong effect on Tg, which ranged from − 27.5–50.3 °C for powders stored at 0.113 and 0.328 aw, while spray drying temperature had the least effect. Addition of maltodextrin only improved storage properties at aw above 0.529 by lowering Xe and particle size (<20 µm). This has implications on powder handling where water activity can be controlled to below 0.529 to avoid the diluting effect of maltodextrin on protein content when it is not required as part of the food formulation. These results show the variable effects that process conditions have on powder properties and the need to consider handling and storage separately.

Nixtamalized maize supplementation with a sardine protein concentrate to improve the biological value of tortillas

Nixtamalized maize supplementation with a sardine protein concentrate to improve the biological value of tortillas

Peptide profile of the sardine protein hydrolysate affects food utilization and intestinal microbiota of Nile tilapia

Peptide profile of the sardine protein hydrolysate affects food utilization and intestinal microbiota of Nile tilapia

Effects of short- and long-term treatments of sardine (Sardina pilchardus) protein hydrolysates on blood lipid concentrations and antioxidant status, in rats fed cholesterol-enriched diets

Hypercholesterolemia is a major risk factor of cardiovascular diseases (CVD). A limited number of experimental studies have shown that sardine protein hydrolysates (SPH) could be a very useful natural compound to prevent hy-percholesterolemia by both improving the lipoprotein profile and modula-ting oxidative stress. In the present study, the effect of short and long term treatments with SPH were examined on serum lipid contents, lipid peroxida-tion and antioxidant enzymes activities in rats fed cholesterol-enriched diet. At day 0, rats were divided into five groups. The group of day 0 was the stan-dard group, and the four remaining groups were divided into two parts of two groups each consuming for 14 or 28 days an hypercholesterolemic diet, and treated (HC-SPH) or not (HC) by gavage with SPH. Compared with day 0, serum TC contents were increased at day 14 and remained unchanged at day 28 in HC-SPH group. These values were decreased in HC-SPH versus HC. Liver and heart TBARS concentrations were increased at day 14 then diminished at day 28 in HC-SPH group. Liver and heart SOD and CAT activities were decrea-sed at short term then remained unchanged at long term in HC-SPH group. In addition, these activities were enhanced in HC-SPH versus HC. In conclusion, these results indicate the potential effects of short and long term treatments of SPH to improved cholesterolemia and reduced radical attack in rats fed high-cholesterol diets.

Protective properties of sardine and chickpea protein hydrolysates against lipoprotein oxidative damages and some inflammation markers in hypercholesterolemic rats

OBJECTIVE: This study evaluated the effect of sardine (SPH) and chickpea protein hydrolysates (CPH) on oxidant stress and inflammatory profile in cholesterol-fed rats. METHODS: The experiment was undertaken for thirty days on 18 cholesterol-fed Wistar rats (220±10 g) divided into three groups and receiving 1 g/kg of body weight either chickpea protein hydrolysate (CPH), sardine protein hydrolysate (SPH) or casein in water (CG). RESULTS: Compared to CG, SPH and CPH treatment reduced cholesterol, hydroperoxide and malondialdehyde contents in serum, lipoproteins, erythrocytes and aorta. These same treated groups showed also lower serum isoprostane levels. However, serum paraoxonase activity and HDL-antioxidant property were improved only by CPH compared to CG. SOD activity of aorta and erythrocytes was higher in CPH but in SPH group, SOD activity was lower in these tissues and remained unchanged in serum. Furthermore, CPH and SPH stimulated glutathione peroxidase and catalase activities of aorta and erythrocytes. In CPH group, nitric oxide levels of serum, erythrocytes and aorta were increased by respectively 1.4- to 1.8-fold compared to CG and SPH. In addition, among the three groups, CPH exhibited the best anti-inflammatory effect by lowering serum C reactive protein, uric acid and albumin concentrations. CONCLUSIONS: SPH and particularly CPH possess antioxidant and anti-inflammatory properties and could be useful as nutraceuticals for health improving and preventing numerous disorders such as cardiovascular diseases.

Bioactive Protein Hydrolysate Obtained from Canned Sardine and Brewing By-products: Impact of Gastrointestinal Digestion and Transepithelial Absorption

A sardine protein hydrolysate (SPH) was prepared by hydrolysis of sarcoplasmic proteins from canned sardine by-product with proteases from brewer’s spent yeast (BSY). The SPH presented in vitro angiotensin converting enzyme-inhibitory (ACE-I) and ferric reducing antioxidant potential (FRAP). However, the challenge before in vivo efficacy studies is to understand the impact of ultrafiltration (UF), simulated gastrointestinal (GI) digestion, and the intestinal cell permeability. Thus, this work was carried out to study the influence of these parameters on SPH bioactivity; two predictive models for human intestinal absorption were compared. Results showed that ACE-I and antioxidant activities were improved after UF of SPH through a 10 kDa cut-off membrane; simulated GI increased the FRAP value whereas the ACE-I remained similar. The apparent permeability coefficients of < 10 kDa fraction evaluated using Caco-2 and Caco-2/HT29-MTX cell models were 5.89 × 10−6 cm/s and 10.93 × 10−6 cm/s, respectively. Mass spectrometry revealed that molecules with m/z between 1000 and 5000 were transported across Caco-2/HT29-MTX cell monolayer. Basolateral permeates presented antioxidant activity but no ACE-I activity was detected. These results suggest that SPH prepared by BSY proteases is promising as functional ingredient with enhanced antioxidant activity and justifies further in vivo studies to confirm its pharmacological efficacy.

Sardine (Sardinella spp.) protein hydrolysate as growth promoter in South American catfish (Rhamdia quelen) feeding: Productive performance, digestive enzymes activity, morphometry and intestinal microbiology

This study evaluated the effects of dietary inclusion of sardine (Sardinella spp.) protein hydrolysate (SPH) on productive performance, digestive enzymatic activity, morphology and intestinal microbiology of South American catfish (Rhamdia quelen) juveniles. SPH was produced from sardine processing wastes using Protamex® protease complex from Novozymes A/S. Four levels of inclusion were evaluated (0, 2, 5 and 10%). A total of 480 South American catfish juveniles (average weight 11.3 ± 2.46 g) were distributed in 24 polyethylene containers, in a completely randomized design with four treatments and six replications. The fish were fed twice daily until apparent satiation with isoproteic (39%) and isoenergetic (4376 kcal.kg−1) diets for 56 days. Regardless of the SPH inclusion levels in the diets, average weight gains (36.28 g), specific growth rate (2.56% day−1), apparent feed intake (40.51 g) and apparent feed conversion rate (1.12) were improved when compared to the control treatment (average of 24.95 g; 2.11% day−1; 31.00 g and 1.28, respectively). Total alkaline protease activity of the gastrointestinal tract of the South American catfish juveniles was higher in the treatment that received 5% SPH (0.61 ± 0.23 U. mg−1 of protein) than in the control (0.26 ± 0.08 U.mg−1 of protein). The amylase activity was higher in the treatments with 2% SPH (1.58 ± 0.19 U. mg−1 of protein) and 5% SPH (1.43 ± 0.44 U. mg−1 of protein) when compared to the control (0.40 ± 0.18 U. mg−1 of protein). In the 5% SPH treatment, higher amounts of lactic acid bacteria and Vibrionaceae were detected than in the other treatments. No difference was found for total heterotrophic bacteria. There was no difference in the intestinal morphometry of the South American catfish for any one of the analyzed parameters. Inclusion levels of up to 10% SPH in the diets of South American catfish showed improvement in the productive performance and nutritional efficiency, acting as a growth promoter. The inclusion level of 5% SPH caused an increase in the digestive enzymatic activity and populations of intestinal lactic acid bacteria. Thus, a prebiotic effect on the fishes was observed and the inclusion level may determine the effects of SPH.

Les protéines purifiées à partir de sardines améliorent les chiffres tensionnels, l’équilibre glycémique, les voies métaboliques anti-athérogènes et la capacité anti-oxydante, chez le rat obèse

Aim of the studyThe effects of sardine by-products (SBy-P) and fillet proteins (SF-P) were compared to casein (Cas) ; these effects were assessed on blood pressure, glycemic control, reverse cholesterol transport, lipid peroxidation and total antioxidant capacity in obese rats. Materials and methodsEighteen male Wistar rats were subjected for three months, to a high-fat diet. The obese rats were divided into three groups and consumed the same high-fat diet for 28 days after addition of either, 20% SBy-P, SF-P or Cas. ResultsThe sardine proteins (SBy-P and SF-P) compared respectively to Cas, reduced diastolic (−14%, −11% P<0.05) and systolic pressures (−12%, −8% P<0.05), blood glucose (−24%, −21% P<0.05), glycated hemoglobin (−28%, −21% P<0.05), insulinemia (−29%, −18% P<0.05) and HOMA-IR index (−29%, −18% P<0.05). They improve the reverse cholesterol transport by increasing the lecithin: cholesterol acyltransferase (LCAT) activity (+43%, +30% P<0.05) and high-density lipoproteins in cholesterol esters (+108%, +88% P<0.05), and decreasing the atherogenicity ratios and membrane fluidity (P<0.05). Furthermore, SBy-P and SF-P induced a reduction of reactive thiobarbituric acid substances concentrations in heart (−45%, −25% P<0.05), aorta (−62%, −41% P<0.05), liver (−40%, −21% P<0.05) and adipose tissue (−50%, −37% P<0.05) with an improvement in antioxidant capacity. ConclusionSardine proteins, in particular those extracted from by-products, because of their hypotensive, hypoglycemic, anti-atherogenic and antioxidant properties, may have protective effects against the cardiovascular risk associated with obesity.

Sardine proteins (Sardina pilchardus) combined with green lemon zest (Citrus latifolia) improve blood pressure, lipid profile and redox status in diabetic hypertensive rats

PurposeThis paper aims to study the effect of green lemon zest combined with sardine proteins in diabetic hypertensive rats (DHRs).Design/methodology/approachMale Wistar rats (n = 30) weighing 250 ± 10 g were divided into five groups. The first group consumed a diet containing 20 per cent casein (C). The other four groups are rendered diabetic by intraperitoneal injection of streptozotocin (40 mg/kg body weight), then hypertensive by subcutaneous implantation controlled time-release pellet containing ouabain (0.25 mg/pellet). One untreated group (DHR) consumed 20 per cent casein and the three other groups consumed the same diet supplemented with 2 per cent green lemon zest (DHR-lz), or with 20 per cent of sardine protein (group DHR-sp) or with the combination of both sardine proteins and green lemon zest (group DHR-sp + lz).FindingsDHRs feeding on the combination of both sardine protein (sp) and lemon zest (lz) induced a significant decrease of diastolic blood pressure and heart rates values compared with DHR (p < 0.05). The HDLC values were increased by +55 per cent in DHR-sp + lz compared with DHR group. Moreover, plasma non-HDLC concentrations were decreased significantly compared to DHR, DHR-lz, DHR-sp and C groups. In DHR-sp + lzvs DHR group, TBARS values were decreased by −25 per cent in the liver. Moreover, kidney TBARS were significantly reduced by −66, −51, −65 and −67 per cent compared with C, DHR, DHR-lz and DHR-sp, respectively.Originality/valueThese results suggest that consumption of green lemon zest combined with sardine proteins can reduce blood pressure and tissue oxidative damage and, therefore, help to prevent cardiovascular complications in hypertensive diabetic patients.

Protein hydrolysate from canned sardine and brewing by-products improves TNF-α-induced inflammation in an intestinal-endothelial co-culture cell model.

The anti-inflammatory activity of sardine protein hydrolysates (SPH) obtained by hydrolysis with proteases from brewing yeast surplus was ascertained. For this purpose, a digested and desalted SPH fraction with molecular weight lower than 10kDa was investigated using an endothelial cell line (EA.hy926) as such and in a co-culture model with an intestinal cell line (Caco-2). Effects of SPH <10kDa on nitric oxide (NO) production, reactive oxygen species (ROS) inhibition and secretion of monocyte chemoattractant protein 1 (MCP-1), vascular endothelial growth factor (VEGF), chemokine IL-8 (IL-8) and intercellular adhesion molecule-1 (ICAM-1) were evaluated in TNF-α-treated and untreated cells. Upon TNF-α treatment, levels of NO, MCP-1, VEGF, IL-8, ICAM-1 and endothelial ROS were significantly increased in both mono- and co-culture models. Treatment with SPH <10kDa (2.0mg peptides/mL) significantly decreased all the inflammation markers when compared to TNF-α-treated control. This protective effect was more pronounced in the co-culture model, suggesting that SPH <10kDa Caco-2 cells metabolites produced in the course of intestinal absorption may provide a more relevant protective effect against endothelial dysfunction. Additionally, indirect cross-talk between two cell types was established, suggesting that SPH <10kDa may also bind to receptors on the Caco-2 cells, thereby triggering a pathway to secrete the pro-inflammatory compounds. Overall, these in vitro screening results, in which intestinal digestion, absorption and endothelial bioactivity are simulated, show the potential of SPH to be used as a functional food with anti-inflammatory properties.

Bio-functional properties of sardine protein hydrolysates obtained by brewer's spent yeast and commercial proteases.

The canned-sardine industry generates large amounts of protein-rich waste, which demands useful exploitation. This paper describes the potential use of muscle and viscera proteins from canned sardine by-products as substrate to obtain hydrolysates with biological and functional properties. Three enzymatic approaches, brewer's spent yeast (Bsy) proteases, Alcalase® and Neutrase® were applied to perform protein hydrolysis at the same proteolytic activity (1 U mL-1 ), using an enzyme/substrate ratio of 20% (v/v), at 50°C and for 7 h. Hydrolysis degree (DH), antioxidant and angiotensin I-converting enzyme inhibitory (ACE-I) activities, functional properties (i.e. solubility, emulsifying and foaming properties, water and oil binding capacity) and colour were investigated. All hydrolysates presented a high protein content [52.7-83.2% dry weight (DW)] and low fat content (0.9-3.9% DW). Alcalase® treatment of muscle and viscera proteins resulted in higher DH (7.5% and 8.6%, respectively) and higher biological activities (P < 0.05). All hydrolysates had excellent solubility and presented functional properties. Among viscera hydrolysates, treatment with Bsy proteases promoted higher emulsion (80.1 m2 g-1 ), foaming (79.2%) and oil binding capacity (5.8 g g-1 ) of viscera sardine proteins. Improved biological and functional properties were observed for sardine protein hydrolysates produced using the three enzymatic treatments tested. © 2017 Society of Chemical Industry.

Fração solúvel de hidrolisado proteico de sardinha na alimentação do jundiá

O objetivo deste trabalho foi avaliar o efeito da inclusão da fração solúvel do hidrolisado proteico de sardinha sobre a estabilidade das dietas e a excreção de amônia de juvenis de jundiá. Foram elaboradas sete dietas experimentais com as frações solúveis dos hidrolisados de músculo e ví­­sceras de sardinha. A determinação da estabilidade do pellet na água foi medida em intervalos de tempo diferentes (5 min, 10 min, 20 min, 30 min, 1 h e 1,5 h). A determinação de amônia total foi realizada a cada cinco horas. Como resultado do teste de estabilidade foi detectado diferença significativa somente no perí­­odo de 5 minutos, onde a dieta contendo 20% de hidrolisado solúvel de musculo teve maior taxa de lixiviação em comparação com a dieta controle. A partir de 10 horas de observação, a concentração de amônia foi maior no controle em relação aos outros tratamentos. O hidrolisado proteico de resí­­duo de sardinha tem grande potencial para ser utilizado nas rações do jundiá, melhorando a eficiência ambiental das dietas. A inclusão de até 10% da fração solúvel de hidrolisados de músculo e de ví­­sceras de sardinha não afeta a estabilidade das dietas, além de diminuir a excreção de amônia.

Angiotensin-I-Converting Enzyme Inhibitory Activities and In Vivo Antihypertensive Effects of Sardine Protein Hydrolysate.

In our previous study, an antihypertensive protein hydrolysate was prepared from sardine. This study aimed to investigate the composition of sardine protein hydrolysate (SPH) and it's in vivo antihypertensive effect. SPH was separated sequentially with ultrafiltration and size exclusion chromatography. Fractions with high angiotensin-I-converting enzyme (ACE) inhibitory activity were further analyzed with RP-HPLC and amino acids analysis. Then, SPH was individually oral administrated to spontaneously hypertensive rats (SHR) and normotensive wistar kyoto rats (WKY) for 4 wk. After treatment, the systolic blood pressure (SBP), organindex, oxidative status, serum ACE activity, and serum angiotensin-II (ANG-II) of all the rats were determined. According to the separation and analysis results, 3 main fractions with high ACE-inhibitory activity were obtained with different amino acids composition. The animal experiments results showed that SPH could significantly reduce SBP (P < 0.05 or P < 0.01) within 4 h after a single oral administration. After a chronic oral administration, a steady state of SBP in SHR rats was attained. The heart weight index and left ventricular weight index were significantly reduced (P < 0.05) in SPH-treated SHR rats. The malonyldialdehyde (MDA) levels in organs and serum, serum ACE activity, and serum ANG-II concentration in SPH-treated SHR rats were significantly lowered (P < 0.05 or P < 0.01) as compared to their controls. Meanwhile there was no significant effect (P > 0.05) on those parameters in WKY rats. These results indicate that SPH can decrease blood pressure in SHR rats and not in WKY rats.

P-219: Effects of fish protein on brain lipid peroxidation and antioxidant enzymes in an experimental model of metabolic syndrome

Background The purpose of the present study was to investigate the protective effects of fish protein on brain glucose, lipid peroxidation and antioxidant enzymes in an experiment of metabolic syndrome. Methods Tweenty male Wistar rats were fed for 2 months sardine protein (S) or casein (C) with or without high fructose (HF) (64%). Changes in body weight, intake of food and water, and brain weight were measured. Brain glucose, TBARS, hydroperoxides, enzymatic antioxidants such as catalase (CAT) and glutathione peroxidase (GSH-Px) were also performed. Results Despite lower food and water intakes, the body mass index (BMI), body weight, absolute and relative brain weights and brain glucose were higher in fructose-fed rats than in controls rats. Moreover, an increase in hydroperoxides and a decrease in CAT and GSH Px were observed in rats on a high-fructose diet than in those on control diets. Administration of sardine protein for 60 days to HF rats resulted in significant attenuation of BMI, food intake, brain glucose and hydroperoxides and improved antioxidant enzyme activities in the brain as compared to casein-HF. Conclusions In conclusion, these results provide further evidence in support of the favorable effects of the sardine protein upon the metabolic disturbances prevailing in the fructose-induced metabolic syndrome

P-221: Sardine and bogue protein hydrolysates protect aorta by improving antitherogenic propertie of HDL in hypercholesterolemic rat

Objectifs Il est bien etabli que les lipoproteines jouent un role important dans le processus de l'atherosclerose et particulierement les HDL qui agissent contre cette pathologie vasculaire. Le but de ce travail est d'etudier si les hydrolysats de proteines de sardine (HPS) ou de bogue (HPB) protegent l'aorte en ameliorant les proprietes antioxydantes des HDL chez le rat hypercholesterolemique. Methodes 18 rats mâles Wistar (210 ± 10 g), repartis en trois groupes de six rats chacun, consommant durant 28 jours un regime a 20 % de caseine supplemente avec 1 % de cholesterol alimentaire et 0,5 % d'acide cholique. Les deux groupes traites recoivent quotidiennement, par gavage, 250 mg/Kg PC une solution de HPS ou de HPB. Le troisieme groupe recoit de l'eau et constitue le groupe controle (GC) Resultats HPS et HPB ont reduit la cholesterolemie de – 66 %, cette diminution correspond principalement aux faibles contenus en cholesterol-VLDL (– 78 %). En outre, le cholesterol-LDL est 1,4 – fois plus faible chez HPB. Chez ce meme groupe, l'APOA4-HDL, l'activite LCAT, paraoxonase et glutathion peroxydase sont augmentes respectivement de + 33 %, + 23 %, + 20 % et + 110 %. Les concentrations en malondialdehyde des LDL sont reduites de – 50 % avec HPB alors qu’elles restent inchangees avec HPS. Au niveau de l'aorte les concentrations en malondialdehyde sont diminuees de – 66 % et – 70 % avec HPS et BPH. Les teneurs en carbonyles – 36 % plus en carbonyle chez ces deux groupes compares aux temoins Conclusion Donc HPS et en particulier HPB protegent l'aorte via l'action antiatherogene des HDL qui assument un efflux du cholesterol et une action antioxydant efficace

P-220: Sardine protein compared to casein combined with sardine oil or milk lipids modulate differently dyslipidemia and lipid peroxidation of tissues and lipoproteins in rats fed an atherogenic diet

Objectifs Voir si les proteines de sardine comparees a la caseine, combinees aux lipides du lait ou a l'huile de sardine peuvent moduler differemment la dyslipidemie et attenuer le stress oxydatif induit par un regime atherogene. Methodes Des rats mâles (n = 24) pesant 200 ± 10 g sont divises en 4 groupes et recoivent pendant 28 jours, 20 % de proteines de sardine ou de caseine combinees a 5 % d'huile de sardine (PsHS et casHS) ou de lipides du lait (PsLL et casLL). Les 4 regimes sont supplementes avec 1 % de cholesterol et 0,5 % d'acide cholique. Resultats Une hypercholesterolemie similaire est notee chez les groupes consommant les lipides du lait (PsLL et casLL), alors que chez ceux consommant l'huile de sardine (PsHS et casHS), la cholesterolemie est normale. Le cholesterol total (CT) est diminue de 46 % chez le groupe PsHS vs PsLL. L'hypertriglyceridemie notee chez les groupes PsHS et PsLL est identique mais reduite de 70 % chez le groupe casHS vs PsHS. Les valeurs des substances reactives a l'acide thioabarbituriique (TBARS) des lipoproteines de tres faible densite (VLDL) sont diminuees de 50 % chez casHS vs casLL, 64 % chez PsHS vs casHS et de 73 % chez PsLL vs casLL. Dans la fraction de faible densite (LDL-HDL1), les valeurs des TBARS sont significativement abaissees (– 287 %) chez casHS vs casLL, 90 % chez PsHS vs casHS et de 44 % chez PsLL vs casLL. Le contenu des HDL2 (lipoproteine de haute densite) en TBARS est abaisse (– 49 %) chez le groupe PsHS vs PsLL. Au niveau des HDL3, les teneurs en TBARS sont diminuees respectivement de 43 % et 79 % chez casHS et PsLL comparees a casLL et de 88 % et 67 % chez PsHS vs casHS et PsLL, respectivement. Au niveau tissulaire, les TBARS sont reduits au niveau du cœur (2,4-fois), cerveau (4,7-fois) et aorte (2,3-fois) chez casLL vs PsLL. De meme, une reduction des TBARS est notee au niveau du cœur (3,3-fois) et du cerveau (6,5-fois) chez le groupe casLL vs casHS. Au niveau de l'aorte, les valeurs des TBARS sont 5-fois plus faibles chez casHS vs PsHS mais augmentees au niveau du cœur (16-fois) et du cerveau (3-fois). Chez le groupe PsLL vs PsHS, les TBARS du cœur et du cerveau sont 11 – et 2,2-fois plus eleves. Conclusion Chez le rat consommant un regime atherogene, la proteine de sardine combinee aux lipides du lait est hypercholesterolemiante, hypertriglyceridemiante et n’attenue pas la peroxydation lipidique au niveau de certains tissus cibles de l'atherosclerose.

Effect of sardine proteins on hyperglycaemia, hyperlipidaemia and lecithin:cholesterol acyltransferase activity, in high-fat diet-induced type 2 diabetic rats.

Type 2 diabetes (T2D) is a major risk factor of CVD. The effects of purified sardine proteins (SP) were examined on glycaemia, insulin sensitivity and reverse cholesterol transport in T2D rats. Rats fed a high-fat diet (HFD) for 5 weeks, and injected with a low dose of streptozotocin, were used. The diabetic rats were divided into four groups, and they were fed casein (CAS) or SP combined with 30 or 5% lipids, for 4 weeks. HFD-induced hyperglycaemia, insulin resistance and hyperlipidaemia in rats fed HFD, regardless of the consumed protein. In contrast, these parameters lowered in rats fed SP combined with 5 or 30% lipids, and serum insulin values reduced in SP v. CAS. HFD significantly increased total cholesterol and TAG concentrations in the liver and serum, whereas these parameters decreased with SP, regardless of lipid intake. Faecal cholesterol excretion was higher with SP v. CAS, combined with 30 or 5% lipids. Lecithin:cholesterol acyltransferase (LCAT) activity and HDL3-phospholipids (PL) were higher in CAS-HF than in CAS, whereas HDL2-cholesteryl esters (CE) were lower. Otherwise, LCAT activity and HDL2-CE were higher in the SP group than in the CAS group, whereas HDL3-PL and HDL3-unesterified cholesterol were lower. Moreover, LCAT activity lowered in the SP-HF group than in the CAS-HF group, when HDL2-CE was higher. In conclusion, these results indicate the potential effects of SP to improve glycaemia, insulin sensitivity and reverse cholesterol transport, in T2D rats.

Sardine protein diet increases plasma glucagon-like peptide-1 levels and prevents tissue oxidative stress in rats fed a high-fructose diet.

The current study investigated whether sardine protein mitigates the adverse effects of fructose on plasma glucagon‑like peptide-1 (GLP-1) and oxidative stress in rats. Rats were fed casein (C) or sardine protein (S) with or without high‑fructose (HF) for 2 months. Plasma glucose, insulin, GLP‑1, lipid and protein oxidation and antioxidant enzymes were assayed. HF rats developed obesity, hyperglycemia, hyperinsulinemia, insulin resistance and oxidative stress despite reduced energy and food intakes. High plasma creatinine and uric acid levels, in addition to albuminuria were observed in the HF groups. The S‑HF diet reduced plasma glucose, insulin, creatinine, uric acid and homeostasis model assessment‑insulin resistance index levels, however increased GLP‑1 levels compared with the C‑HF diet. Hydroperoxides were reduced in the liver, kidney, heart and muscle of S‑HF fed rats compared with C‑HF fed rats. A reduction in liver, kidney and heart carbonyls was observed in S‑HF fed rats compared with C‑HF fed rats. Reduced levels of nitric oxide (NO) were detected in the liver, kidney and heart of the S‑HF fed rats compared with C‑HF fed rats. The S diet compared with the C diet reduced levels of liver hydroperoxides, heart carbonyls and kidney NO. The S‑HF diet compared with the C‑HF diet increased the levels of liver and kidney superoxide dismutase, liver and muscle catalase, liver, heart and muscle glutathione peroxidase and liver ascorbic acid. The S diet prevented and reversed insulin resistance and oxidative stress, and may have benefits in patients with metabolic syndrome.

A comparison between the impact of two types of dietary protein on brain glucose concentrations and oxidative stress in high fructose-induced metabolic syndrome rats.

The present study explored the potential of fish proteins to counteract high glucose levels and oxidative stress induced by fructose in the brain. A total of 24 male Wistar rats consumed sardine protein or casein with or without high fructose (64%). After 2 months, brain tissue was used for analyses. The fructose rats exhibited an increase in body mass index (BMI), body weight, absolute and relative brain weights and brain glucose; however, there was a decrease in food and water intake. Fructose disrupts membrane homeostasis, as evidenced by an increase in the brain hydroperoxides and a decrease in catalase (CAT) and glutathione peroxidase (GSH-Px) compared to the control. The exposure to the sardine protein reduced BMI, food intake, glucose and hydroperoxides, and increased CAT and GSH-Px in the brain. In conclusion, the metabolic dysfunctions associated with the fructose treatment were ameliorated by the presence of sardine protein in the diet by decreasing BMI, brain glucose and lipid peroxidation, and increasing CAT and GSH-Px activities.

Les protéines de sardine atténuent l'hyperglycémie et le stress oxydant chez le rat diabétique de type2

Introduction. Le diabète s'accompagne d'un stress oxydant favorisant le développement de la maladie. Objectif. L'effet des protéines de sardine (PS) est déterminé sur l'équilibre glycémique, et le statut antioxydant chez des rats présentant un diabète de type 2. Matériel et méthodes. Des rats mâles consomment un régime hyperlipidique (RH) pendant 5 semaines, suivi de l'injection d'une faible dose de streptozotocine. Les rats diabétiques (n = 24) sont répartis en 4 groupes et sont soumis à un régime à 20% de caséine (CAS) ou de PS associées à 5 ou 30% de lipides (RH-CAS ou RH-PS), pendant 28 jours. Résultats. Une réduction du glucose sérique, de l'HbA1c et de l'insulinémie est notée chez le groupe PS vs CAS. De plus, l'indice HOMA-IR diminue chez le groupe PS vs CAS associé à 5 ou 30% de lipides. Des concentrations élevées en substances réactives à l'acide thiobarbiturique (TBARS) sont notées avec RH au niveau du coeur et des reins. Les teneurs en carbonyles sont augmentées au niveau de tous les organes chez le groupe RH-CAS vs CAS, alors que les PS entraînent une diminution des teneurs en TBARS et en carbonyles au niveau des tous les organes. Chez le groupe RH-CAS vs CAS, l'activité de la superoxyde dismutase (SOD) et la glutathion peroxidase (GPx) est réduite au niveau de tous les organes, et celle de la catalase (CAT) au niveau du foie et des reins. De plus, l'activité de la SOD et de la GPx est réduite au niveau des reins chez le groupe RH-PS vs PS, alors que les PS augmentent l'activité de toutes les enzymes tissulaires, quelle que soit la teneur en lipides dans le régime. CFonclusion. Les PS améliorent l'équilibre glycémique et atténuent les marqueurs du stress oxydant en stimulant l'activité des enzymes antioxydantes tissulaires.