Effect of gastrointestinal alterations mimicking elderly conditions on in vitro digestion of meat and soy proteins

We evaluated the digestion of meat (chicken, beef, and pork) and soy proteins under in vitro conditions mimicking gastrointestinal (GI) conditions of adults (control, C) and elderly with achlorhydria (EA). The changes in degree of hydrolysis (DH), SDS-PAGE profiles, peptide concentration, and proteomics profiles during the digestion process were investigated. Digestion under the EA condition markedly decreased the DH of all protein sources, especially for soy protein. SDS-PAGE profiling and proteomics showed that myofibrillar/sarcoplasmic protein from meat and glycinin/beta-conglycinin from soy were the proteins most affected by the different digestive conditions. Our results indicated that the difference in the digestibility of meat protein between EA and control conditions gradually narrowed from the gastric to the intestinal phase, while a pronounced difference between control and EA conditions was maintained also in the intestinal phase. This work provides new insights of value for future dietary recommendations for elderly individuals.

Impact of Simulated Gastrointestinal Conditions on Antiglycoxidant and α-Glucosidase Inhibition Capacities of Cyanidin-3-O-Glucoside

Cyanidin-3-O-glucoside (C3G) is a widespread anthocyanin derivative, which has been reported in vitro to exert potent antioxidant, antiglycation and α-glucosidase inhibition effects. Nevertheless, the physiological relevance of such properties remains uncertain considering its significant instability in gastrointestinal conditions. A simulated digestion procedure was thus instigated to assess the influence of gastric and intestinal media on its chemical integrity and biological activities. HPLC analyses of digested C3G samples confirmed the striking impact of intestinal conditions, as attested by a decomposition ratio of 70%. In contrast, with recovery rates of around 90%, antiglycation, as well as DPPH and ABTS scavenging assays, uniformly revealed a noteworthy persistence of its antiglycoxidant capacities. Remarkably, a prominent increase of its α-glucosidase inhibition activity was even observed after the intestinal phase, suggesting that classical in vitro evaluations might underestimate C3G antidiabetic potential. Consequently, the present data provide novel and specific insights on C3G’s digestive fate, suggesting that the gastrointestinal tract does not profoundly affect its positive action on oxidative and carbonyl stresses. More specifically, it also tends to support its regulating effects on postprandial hyperglycemia and its potential usefulness for diabetes management.

Bioaccessibilities and health risk assessment of heavy metals in dust from the Guizhou-Guiyang urban zone, China

To investigate the health risks of heavy metals in dust entering the human body from different exposure pathways. In this study, the old urban area of Guiyang was used as the study area to understand the heavy metals concentrations in surface dust, including recreational plazas, main streets, hospitals, residential areas, and schools in this city, and the bioaccessibility in the simulated lung phase and simulated gastrointestinal phase. The results showed that the concentrations of Cu, Pb, Zn, Cd, Ni, and Cr in the dust were higher than the background values, especially the Zn content exceeded the background value by 9.71 times. The bioaccessibility results indicated that the most soluble heavy metals in the simulated lung phase, simulated gastric phase, and simulated intestinal phase were Zn, Ni, and Cu, respectively, and the bioaccessibility of most heavy metals was significantly higher in the gastric phase than in the intestinal phase, and only Cu was higher in the intestinal phase than in the gastric phase. The linear results fit suggested that the total amount of heavy metals alone could not predict the human intake of heavy metals in the dust. Human health risk assessment based on bioaccessibility showed that children had higher non-carcinogenic and carcinogenic risks than adults for both hand-to-mouth ingestion and respiratory inhalation exposure pathways, but none of them exceeded the limit values.

Formation of Lipid and Protein Oxidation Products during In Vitro Gastrointestinal Digestion of Dry-Cured Loins with Different Contents of Nitrate/Nitrite Added

The effect of nitrate/nitrite (0, 37.5, 75, and 150 mg/kg) in the dry-cured loin formulation on the formation of lipid and protein oxidation products during in vitro digestion was evaluated. Dry-cured loins formulated with nitrate/nitrite resulted in significantly less lipid and protein oxidation than uncured loins before and after simulated digestion. Compared to loins added with 0 mg/kg nitrate/nitrite, dry-cured loins with 37.5, 75, and 150 mg/kg contained a significantly lower content of conjugated dienes, malondialdehyde, carbonyls, and non-heme iron, and higher amounts of nitrosylmioglobin and thiols. During in vitro digestion, the content of conjugated dienes, malondialdehyde, and carbonyls increased, while thiol content decreased, indicating the development of lipid and protein oxidative processes. At the end of the intestinal phase, the 75 mg/kg digests had a significantly higher content of conjugated dienes, while no differences were found among the other digests. During the in vitro intestinal phase (180 and 240 min), nitrate/nitrite curing resulted in significantly lower malondialdehyde concentrations in the 37.5, 75, and 150 mg/kg loin digests than in the uncured loin digests. No significant differences were observed at the end of the intestinal digestion phase between the cured loin digests. Digests of dried loins without nitrate/nitrite addition showed higher carbonyl contents than the nitrate/nitrite cured counterparts. The loss of thiols was significantly higher in loin digests without added nitrate/nitrite than in loin digests with different amounts of curing salts. The addition of 37.5 mg/kg nitrate/nitrite in the cured loin formulation prevents the formation of lipid peroxidation products and carbonyls from protein oxidation and thiol loss during digestion

Effect of Freeze Drying and Simulated Gastrointestinal Digestion on Phenolic Metabolites and Antioxidant Property of the Natal Plum (Carissa macrocarpa)

Natal plums (Carissa macrocarpa) are a natural source of bioactive compounds, particularly anthocyanins, and can be consumed as a snack. This study characterized the impact of freeze drying and in vitro gastrointestinal digestion on the phenolic profile, antioxidant capacity, and α-glucosidase activity of the Natal plum (Carissa macrocarpa). The phenolic compounds were quantified using high performance liquid chromatography coupled to a diode-array detector HPLC-DAD and an ultra-performance liquid chromatograph (UPLC) with a Waters Acquity photodiode array detector (PDA) coupled to a Synapt G2 quadrupole time-of-flight (QTOF) mass spectrometer. Cyanidin-3-O-β-sambubioside (Cy-3-Sa) and cyanidin-3-O-glucoside (Cy-3-G) were the dominant anthocyanins in the fresh and freeze-dried Natal plum powder. Freeze drying did not affect the concentrations of both cyanidin compounds compared to the fresh fruit. Both cyanidin compounds, ellagic acid, catechin, epicatechin syringic acid, caffeic acid, luteolin, and quercetin O-glycoside from the ingested freeze-dried Natal plum powder was quite stable in the gastric phase compared to the small intestinal phase. Cyanidin-3-O-β-sambubioside from the ingested Natal plum powder showed bioaccessibility of 32.2% compared to cyanidin-3-O-glucoside (16.3%). The degradation of anthocyanins increased the bioaccessibility of gallic acid, protocatechuic acid, coumaric acid, and ferulic acid significantly, in the small intestinal digesta. The ferric reducing antioxidant power (FRAP), 2,2′-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid (ABTS) activities, and inhibitory effect of α-glucosidase activity decreased in the small intestinal phase. Indigenous fruits or freeze-dried powders with Cy-3-Sa can be a better source of anthocyanin than Cy-3-G due to higher bioaccessibility in the small intestinal phase.

WPI Gel Microstructure and Mechanical Behaviour and Their Influence on the Rate of In Vitro Digestion

The influence of microstructure and mechanical properties on the in vitro digestibility of 15% whey protein isolate (WPI) gels was investigated. Gels were prepared via heat set gelation at three pH values (pH 3, 5 and 7), which produced gels with distinct microstructures and mechanical properties. The gels were minced to simulate an oral/chewing phase, which led to the formation particles of various sizes and textures. The minced gels were passed through either an Infogest (pre-set pH of 3) or Glass stomach (dynamic pH) protocol. Gels were digested in the gastric phase for up to 120 min, at which point the extent of digestion was measured by the amount of filterable nitrogen passing through a sieve. The digesta from both gastric methods were passed through an in vitro simulated intestinal phase. A strong link was found between the elasticity of the initial gel and the gel particle size following simulated oral processing, which significantly (p < 0.01) affected the rate of digestion in the gastric phase. A weaker correlation was also found between the pH of the gels and the extent of gastric digestion. This work highlights the differences in the rate of gastric digestion, arising from oral processing, which can be attributed to the material properties of the substrate.

CdsH Contributes to the Replication of Salmonella Typhimurium inside Epithelial Cells in a Cysteine-Supplemented Medium

Salmonella Typhimurium is a facultative, intracellular pathogen whose products range from self-limited gastroenteritis to systemic diseases. Food ingestion increases biomolecules’ concentration in the intestinal lumen, including amino acids such as cysteine, which is toxic in a concentration-dependent manner. When cysteine’s intracellular concentration reaches toxic levels, S. Typhimurium expresses a cysteine-inducible enzyme (CdsH), which converts cysteine into pyruvate, sulfide, and ammonia. Despite this evidence, the biological context of cdsH’s role is not completely clear, especially in the infective cycle. Since inside epithelial cells both cdsH and its positive regulator, ybaO, are overexpressed, we hypothesized a possible role of cdsH in the intestinal phase of the infection. To test this hypothesis, we used an in vitro model of HT-29 cell infection, adding extra cysteine to the culture medium during the infective process. We observed that, at 6 h post-invasion, the wild type S. Typhimurium proliferated 30% more than the ΔcdsH strain in the presence of extra cysteine. This result shows that cdsH contributes to the bacterial replication in the intracellular environment in increased concentrations of extracellular cysteine, strongly suggesting that cdsH participates by increasing the bacterial fitness in the intestinal phase of the S. Typhimurium infection.

Stability and Antiglycoxidant Potential of Bilberry Anthocyanins in Simulated Gastrointestinal Tract Model

Anthocyanins from Vaccinium myrtillus fruits have been reported in vitro to exert potent radical scavenging and antiglycation activities. However, the physiological relevance of such properties remains unclear given the potential susceptibility of anthocyanin derivatives to digestive conditions. A simulated gastrointestinal tract model was thus implemented to assess the impact of gastric and intestinal phases on the chemical integrity of bilberry anthocyanins and their antiglycoxidant effects. Results demonstrated that the investigated activities as well as total and individual anthocyanin contents were marginally affected by gastric conditions. By contrast, with recoveries ranging from 16.1 to 41.2%, bilberry anthocyanins were shown to be highly sensitive to the intestinal phase. Of major interest, a much better preservation was observed for radical scavenging and antiglycation activities as attested by recovery rates ranging from 79.1 to 86.7%. Consistently with previous observations, the present study confirms the moderate bioaccessibility of anthocyanin constituents. It does however provide valuable information supporting the persistence of substantial radical scavenging and antiglycation activities at each step of the digestion process. Taken together, these data indicate that digestive conditions might not abolish the potential positive effects of bilberry consumption on both oxidative and carbonyl stresses.

Probiotic bacteria can modulate murine macrophage’s superoxide production in Trichinella spiralis infection

SummaryThe effect of probiotic strains (Enterococcus faecium EF55, E. faecium CCM7420, E. faecium CCM8558, E. durans ED26E/7, Lactobacillus fermentum CCM7421, L. plantarum 17L/1) on the production of superoxide anion (O2-) in peritoneal macrophages of Trichinella spiralis infected mice was examined. E. faecium EF55 and E. faecium CCM8558 strains increased the O2-production prior to parasitic infection,at the day7of application.A significant inhibition of the O2- production caused by T. spiralis infection on day 5 post infection (p.i.) was prevented by all examined strains. Lactobacilli stimulated metabolic activity of macrophages during intestinal and early muscular phase (from day 5 to 25 p.i.) of trichinellosis. Enterococci increased the O2- production in early intestinal phase (day 5 p.i.) and during the muscular phase of trichinellosis (days 25 and 32 p.i.). Respected increase in macrophage’s metabolic activity induced by probiotic treatment in the intestinal phase of trichinellosis augmented the host antiparasite defence (damage and killing of newborn larvae with reactive oxygen species from macrophages).