Dual effects of dietary carnosine during in vitro digestion of a Western meal model with added ascorbic acid.

The beneficial role of carnosine during in vitro digestion of meat was previously demonstrated, and it was hypothesized that such benefits could also be obtained in a meal system. The current study, therefore, assessed carnosine effects on markers of lipid and protein oxidation and of advanced glycation end products (AGEs) during gastric and duodenal in vitro digestion of a burger meal model. The model included intrinsic (low) and enhanced (medium and high) carnosine levels in a mix of pork mince and bread, with or without ascorbic acid (AA) and/or fructose as anti- and prooxidants, respectively. In the presence of either AA or fructose, a carnosine prooxidative potential during digestion was observed at the medium carnosine level depending on markers and digestive phases. However, free carnosine found at the high carnosine level exerted a protective effect reducing the formation of 4-hydroxynonenal in the gastric phase and glyoxal in both the gastric and duodenal phases. Dual effects of carnosine are likely concentration related, whereby at the medium level, free radical production increases through carnosine's ferric-reducing capacity, but there is insufficient quantity to reduce the resulting oxidation, while at the higher carnosine level some decreases in oxidation are observed. In order to obtain carnosine benefits during meal digestion, these findings demonstrate that consideration must be given to the amount and nature of other anti- and prooxidants present and any potential interactions. PRACTICAL APPLICATION: Carnosine, a natural compound in meat, is a multifunctional and beneficial molecule for health. However, both pro- and antioxidative effects of carnosine were observed during digestion of a model burger meal when ascorbic acid was included at a supplemental level. Therefore, to obtain benefits of dietary carnosine during digestion of a meal, consideration needs to be given to the amount and nature of all anti- and prooxidants present and any potential interactions.

[The Mechanism of Resveratrol on Acute T-Lymphocyte Leukemia through IL-7-Mediated JAK / STAT Signaling Pathway].

OBJECTIVE: To explore the roles and relative mechanism of resveratrol against T-ALL through detecting the signaling molecules in IL-7 and JAK/STAT pathway. METHODS: In vitro experiments, Molt4 cells were divided into 3 groups, including the control group, the DMSO group and resveratrol-treated group (Res group). The control group cells without any treatment, the DMSO group cells treated with 0.05% DMSO for 48 hours, the Res group cells treated with 200 µmol/L resveratrol for 48 hours. In vivo experiments, female C57BL/6J mice (6-8 weeks) were randomly divided into the control group, the T-ALL model group (T-ALL group), and Res treatment group (Res group). The control group mice treated with 0.05% DMSO by intragastric treatment, the T-ALL group mice treated with 0.05% DMSO by intragastric treatment, and the Res group mice treated with 10 mg/ml resveratrol. Expression of IL-7, IL-7R and Pim1 mRNA in the cells and mice spleen tissues were detected by RT-qPCR. Cell proliferation ability was detected by CCK-8. The expression of JAK1, JAK3, STAT5, phosphorylated JAK1 (p-JAK1), phosphorylated JAK3 (p-JAK3), phosphorylated STAT5 (p-STAT5) and Pim1 were detected by Western blot. ELISA was used to detect the IL-7 and IL-7R in the cells and mice serum of each groups. RESULTS: Resveratrol could inhibit the proliferation ability of Molt4 cells, decrease the relative levels of p-JAK1, p-JAK3, p-STAT5, Pim1 protein, and the expression levels of Pim1, IL-7 and IL-7R mRNA in cells and mice spleens, reduce the IL-7 and IL-7R in Molt4 cells and mice serum. CONCLUSION: Resveratrol may inhibite IL-7-medicated JAK/STAT signaling pathway to reduce the expression of target protein Pim1 to further exert its anti-T-ALL effects.

Protective effects of dietary carnosine during in-vitro digestion of pork differing in fat content and cooking conditions.

Muscle carnosine represents an important health advantage of meat. Ground pork samples with intrinsic or added carnosine; fat content; and cooked under low or high intensity as a 2 × 2 × 2 factorial were digested in-vitro. Changes in free carnosine and in markers of lipid (hexanal, 4-hydroxynonenal (4-HNE), malondialdehyde (MDA) and protein (protein-carbonyls, thiols) oxidation, and of advanced glycation end-products (AGEs) Nε -(carboxymethyl)lysine (CML) were determined in the saliva, gastric, and duodenal digests. During digestion, the different markers overall indicated increased oxidation and decreased free carnosine. Increasing pork carnosine level significantly reduced protein carbonyls, loss of thiols, and 4-HNE during in-vitro gastric digestion, irrespective of fat and cooking level of the meat. Increased carnosine also significantly reduced hexanal, MDA and CML up to the duodenum phase in moderately cooked lean pork. Besides substantiating the formation of AGEs during digestion, these results show a potentially important role of dietary carnosine occurring in the gastrointestinal tract. PRACTICAL APPLICATIONS: The ailments epidemiologically associated with red meat consumption could be counteracted by ingesting carnosine into meat. The health advantages of dietary carnosine, however, have never been demonstrated during digestion, a unique and complex oxidative environment compounded by the composition and cooking of the meat. The results obtained substantiated that AGEs formation occurred in-vitro in the GIT. They also showed that increased carnosine had an immediate health beneficial role during pork digestion in reducing the formation of different harmful molecules, including AGEs, modulated by the composition and cooking of the meat. However, in exerting this protective role in the GIT, the remaining free level of carnosine, gradually decreased during digestion. Carnosine, as an important meat compositional factor may, depending on the fat content and cooking conditions, change the image of meat from representing a health risk to a health benefit. Carnosine level may also explain discrepancies observed in the literature.