Contribution à l'étude d'oligopeptides (<5 kDa) générés par la préparation et la digestion de deux aliments carnés, la viande bovine et la chair de la truite

Nutritional quality of food proteins has been considered to exceed the mere supply of amino acids since the emergence of the concept of bioactive peptides, i.e. oligopeptides produced mainly by proteolysis, and behaving like modulators of various biological functions. While many bioactive peptides have been discovered in milk protein hydrolysates, their presence within meat and fish products or during digestion of such products has been very little documented to date. In this context, our objectives were to characterise and identify peptides (< 5 kDa) in fish flesh and beef meat after storage/ageing and cooking, and subsequently during in vivo digestive hydrolysis in pig, in intestinal contents and in portal blood. The peptidic fraction in muscle-foods, made of non-proteinic peptides (carnosine, anserine, glutathione) and of peptides formed during the technological processes (storage and cooking), was dependent on the species and on the process used. In cooked beef meat, where numerous peptides were detected, fragments of structural proteins were identified. Among the large number of dietary peptides found in duodenal and jejunal contents, some were systemically observed and may be bioactive peptides or precursors. Beside carnosine, the absorption of which depending on its concentration in meat, many compounds, probably oligopeptides were released in the portal vein following specific patterns after a meal of top loin or of shoulder.La prise de conscience que les qualités nutritionnelles des protéines allaient au-delà de leur capacité à fournir des acides aminés, est apparue avec l'émergence de la notion de peptides bioactifs, c'est-à-dire d'oligopeptides principalement produits par protéolyse, pouvant être des modulateurs de divers processus biologiques. Si de nombreux peptides bioactifs ont été découverts dans des hydrolysats de protéines de lait, leur recherche dans les produits carnés reste à ce jour très peu développée. Dans ce contexte, nos objectifs ont été de caractériser et d'identifier les peptides (< 5 kDa) présents dans la chair de poisson ou viande bovine après conservation/maturation et cuisson, puis au cours de l'hydrolyse digestive in vivo chez le porc dans les contenus intestinaux et dans le sang portal. La fraction peptidique des aliments, constituée des peptides non protéiniques (carnosine, ansérine, glutathion) et de ceux formés au cours des traitements technologiques (conservation et cuisson), était dépendante de l'espèce et des traitements appliqués. Dans la viande bovine cuite, où de nombreux peptides ont été détectés, des fragments de protéines de structure ont été identifiés. Parmi la grande diversité des peptides d'origine alimentaire trouvés dans les contenus duodénaux et jéjunaux, certains d'entre eux, présents de façon systématique, étaient de possibles peptides bioactifs ou leurs précurseurs. Outre la carnosine dont la biodisponibilité dépendait d'abord de sa teneur dans la viande, de nombreux composés, probablement des oligopeptides, étaient libérés dans le sang de la veine porte selon des profils spécifiques après un repas de faux-filet ou de paleron

Contribution à l'étude d'oligopeptides (<5 kDa) générés par la préparation et la digestion de deux aliments carnés, la viande bovine et la chair de la truite

La prise de conscience que les qualités nutritionnelles des protéines allaient au-delà de leur capacité à fournir des acides aminés, est apparue avec l'émergence de la notion de peptides bioactifs, c'est-à-dire d'oligopeptides principalement produits par protéolyse, pouvant être des modulateurs de divers processus biologiques. Si de nombreux peptides bioactifs ont été découverts dans des hydrolysats de protéines de lait, leur recherche dans les produits carnés reste à ce jour très peu développée. Dans ce contexte, nos objectifs ont été de caractériser et d'identifier les peptides (< 5 kDa) présents dans la chair de poisson ou viande bovine après conservation/maturation et cuisson, puis au cours de l'hydrolyse digestive in vivo chez le porc dans les contenus intestinaux et dans le sang portal. La fraction peptidique des aliments, constituée des peptides non protéiniques (carnosine, ansérine, glutathion) et de ceux formés au cours des traitements technologiques (conservation et cuisson), était dépendante de l'espèce et des traitements appliqués. Dans la viande bovine cuite, où de nombreux peptides ont été détectés, des fragments de protéines de structure ont été identifiés. Parmi la grande diversité des peptides d'origine alimentaire trouvés dans les contenus duodénaux et jéjunaux, certains d'entre eux, présents de façon systématique, étaient de possibles peptides bioactifs ou leurs précurseurs. Outre la carnosine dont la biodisponibilité dépendait d'abord de sa teneur dans la viande, de nombreux composés, probablement des oligopeptides, étaient libérés dans le sang de la veine porte selon des profils spécifiques après un repas de faux-filet ou de paleron.Nutritional quality of food proteins has been considered to exceed the mere supply of amino acids since the emergence of the concept of bioactive peptides, i.e. oligopeptides produced mainly by proteolysis, and behaving like modulators of various biological functions. While many bioactive peptides have been discovered in milk protein hydrolysates, their presence within meat and fish products or during digestion of such products has been very little documented to date. In this context, our objectives were to characterise and identify peptides (< 5 kDa) in fish flesh and beef meat after storage/ageing and cooking, and subsequently during in vivo digestive hydrolysis in pig, in intestinal contents and in portal blood. The peptidic fraction in muscle-foods, made of non-proteinic peptides (carnosine, anserine, glutathione) and of peptides formed during the technological processes (storage and cooking), was dependent on the species and on the process used. In cooked beef meat, where numerous peptides were detected, fragments of structural proteins were identified. Among the large number of dietary peptides found in duodenal and jejunal contents, some were systemically observed and may be bioactive peptides or precursors. Beside carnosine, the absorption of which depending on its concentration in meat, many compounds, probably oligopeptides were released in the portal vein following specific patterns after a meal of top loin or of shoulder.CLERMONT FD-BCIU-Santé (631132104) / SudocPARIS-BIUP (751062107) / SudocSudocFranceF

Synthesis and desaturation of cis9, trans11 CLA in adipose tissue of Charolais steers and cull cows

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9cis, 11trans conjugated linoleic acid (CLA) is synthesised and desaturated into conjugated 18 : 3 in bovine adipose tissues

International audienceAlthough endogenous synthesis of conjugated linoleic acid (CLA) in the mammary gland of lactating cows has been already well documented, no study has determined so far as to which tissue and/or organ is involved in CLA synthesis in the growing ruminant except one study showing that CLA synthesis does not occur in ruminant liver. In this context, adipose tissue appears to be a good candidate for endogenous synthesis of CLA in the growing ruminant. The aim of this study was to compare the respective metabolisms of 11trans 18:1 (vaccenic acid, VA) and 9cis,11trans 18:2 (rumenic acid) to that of stearic acid (the preferential substrate of Δ9 desaturase) in adipose tissues (subcutaneous, SC and intermuscular, IM) of six Charolais steers by using the in vitromethod of incubated tissue slices. Samples of SC and IM adipose tissues were incubated at 37°C for 16 h under an atmosphere of 95% O2/5% CO2 in a medium supplemented with 0.75 mM of fatty acid (FA) mixture (representative of circulating non-esterified FA) and 186 μM [1-14C]-18:0 or 58.6 μM [1-14C]-VA or 56 μM [1-14C]-9cis,11trans CLA. Viability of explants was verified by measuring metabolic functions (glucose uptake and glucose-6-phosphate dehydrogenase activity). After 16 h of incubation, FA uptake was similar for all FA (18:0, VA and 9cis,11trans 18:2) in both SC and IM adipose tissues (around 40%). Once in adipose tissue, all FA were preferentially esterified (>80% of cell FA) favouring neutral lipid synthesis (around 90% of esterified FA). Stearic acid was highly (27%) desaturated into oleic acid in SC adipose tissue whereas this desaturation was much lower (6.8%) in IM adipose tissue (P < 0.0001). VA was desaturated into 9cis,11trans CLA at a low extent of about 2.5% to 4.4% in both adipose tissues probably because of a limited affinity of Δ9 desaturase for VA. 9cis,11trans CLA was itself converted by desaturation into 6cis, 9cis,11trans 18:3 at the intensity of 10.8% and 14.5% of cell 9cis,11trans CLA in SC and IM adipose tissues, respectively. In conclusion, bovine adipose tissues of the growing ruminant were especially involved in the endogenous synthesis of CLA from VA and in its desaturation into conjugated derivative, mainly 6cis, 9cis,11trans 18:3, of which biological properties need to be elucidated

Les tissus adipeux, notamment intermusculaires, sont le siège de la synthèse et de la bioconversion du 9CIS,11TRANS CLA chez le bouvillon

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Synthesis and desaturation of cis9, trans11 CLA in adipose tissue of Charolais steers and cull cows

National audienc

Peptides reproducibly released by in vivo digestion of beef meat and trout flesh in pigs

International audienceCharacterisation and identification of peptides (800 to 5000 Da) generated by intestinal digestion of fish or meat were performed using NIS analyses (matrix-assisted laser desorption ionisation time of flight and nano-liquid chromatography electrospray-ionisation ion trap MS/MS). Four pigs fitted with cannulas at the duodenum and jejunum received a meal exclusively made of cooked Pectoralis profundus beef meat or cooked trout fillets. A protein-free meal, made of free amino acids, starch and fat, was used to identify peptides of endogenus origin. Peptides reproducibly detected in digesta (i.e. from at least three pigs) were evidenced predominantly in the first 3 h after the meal. In the duodenum, most of the fish- and meat-derived peptides were characteristic of a peptic digestion. In the jejunum, the majority of peptides appeared to result from digestion by chymotrypsin and trypsin. Despite slight differences in gastric emptying kinetics and overall peptide production, possibly in relation to food Structure and texture, six and four similar peptides were released after ingestion of fish or meat in the duodenum and jejunum. A total of twenty-six different peptides were identified in digesta. All were fragments of major structural (actin, myosin) or sarcoplasmic (creatine kinase, glyceraldehyde-3-phosphate dehydrogenase and myoglobin) muscle proteins. Peptides were short (<2000 Da) and particularly rich in proline residues. Nineteen of them contained bioactive sequences corresponding mainly to an antihypertensive activity. The present work showed that after fish or meat ingestion, among the wide variety of peptides produced by enzymic digestion, some of them can be reproducibly observed in intestinal digesta

Sulfur amino acid deficiency upregulates intestinal methionine cycle activity and suppresses epithelial growth in neonatal pigs

We recently showed that the developing gut is a significant site of methionine transmethylation to homocysteine and transsulfuration to cysteine. We hypothesized that sulfur amino acid (SAA) deficiency would preferentially reduce mucosal growth and antioxidant function in neonatal pigs. Neonatal pigs were enterally fed a control or an SAA-free diet for 7 days, and then whole body methionine and cysteine kinetics were measured using an intravenous infusion of [1-13C;methyl-2H3]methionine and [15N]cysteine. Body weight gain and plasma methionine, cysteine, homocysteine, and taurine and total erythrocyte glutathione concentrations were markedly decreased (−46% to −85%) in SAA-free compared with control pigs. Whole body methionine and cysteine fluxes were reduced, yet methionine utilization for protein synthesis and methionine remethylation were relatively preserved at the expense of methionine transsulfuration, in response to SAA deficiency. Intestinal tissue concentrations of methionine and cysteine were markedly reduced and hepatic levels were maintained in SAA-free compared with control pigs. SAA deficiency increased the activity of methionine metabolic enzymes, i.e., methionine adenosyltransferase, methionine synthase, and cystathionine β-synthase, and S-adenosylmethionine concentration in the jejunum, whereas methionine synthase activity increased and S-adenosylmethionine level decreased in the liver. Small intestine weight and protein and DNA mass were lower, whereas liver weight and DNA mass were unchanged, in SAA-free compared with control pigs. Dietary SAA deficiency induced small intestinal villus atrophy, lower goblet cell numbers, and Ki-67-positive proliferative crypt cells in association with lower tissue glutathione, especially in the jejunum. We conclude that SAA deficiency upregulates intestinal methionine cycle activity and suppresses epithelial growth in neonatal pigs