Pancreatin Digestion Research Articles

Antioxidant properties, ACE/renin inhibitory activities of pigeon pea hydrolysates and effects on systolic blood pressure of spontaneously hypertensive rats.

Legumes are rich sources of protein in human diet and their consumption has been associated with the prevention of chronic diseases attributable to their bioactive components. Pigeon pea (Cajanus cajan) is an underutilized legume with relatively high protein content (~24%). Protein hydrolysates were prepared from pea isolate by enzymatic hydrolysis using pepsin and pancreatin. Hydrolysates were evaluated for their amino acid composition, antioxidant properties, in vitro and in vivo antihypertensive properties. The hydrolysates had high hydrophobic amino acids, especially isoleucine, phenylalanine, and leucine. Pepsin‐pancreatin‐hydrolyzed pea protein (PPHPp) showed significantly higher ability to scavenge DPPH˙ while pancreatin‐hydrolyzed pea protein (PPHPa) had higher ˙OH, ABTS˙+ scavenging, Fe3+ reducing and linoleic acid peroxidation inhibition. PPHPp exhibited superior angiotensin‐converting enzyme inhibition (61.82%) while PPHPa showed higher renin inhibition (14.28%). PPHPp exhibited strong antihypertensive effect, showing an instantaneous systolic blood pressure lowering effect (−26.12 mmHg) within 2‐h post‐oral administration. Pigeon pea protein hydrolysate (especially from pancreatin digest) could therefore, be a promising source of bioactive peptides and potential ingredient for formulation of functional foods against oxidative stress and hypertension.

Protease resistance of food proteins: a mixed picture for predicting allergenicity but a useful tool for assessing exposure

BackgroundSusceptibility to pepsin digestion of candidate transgene products is regarded an important parameter in the weight-of-evidence approach for allergenicity risk assessment of genetically modified crops. It has been argued that protocols used for this assessment should better reflect physiological conditions encountered in representative food consumption scenarios.AimTo evaluate whether inclusion of more physiological conditions, such as sub-optimal and lower pepsin concentrations, in combination with pancreatin digestion, improved the performance of digestibility protocols used in characterization of protein stability.MethodsFour pairs of established allergens and their related non/weakly-allergenic counterparts (seed albumins, muscle tropomyosins, plant lipid transfer proteins [LTP] and collagens) plus fish parvalbumin, were subjected to nine combinations of pH (1.2–2.5–4.0) and pepsin-to-protein ratio (PPR: 10–1–0.1 U/µg) for pepsin digestion, followed by pancreatin digestion in the presence of bile salts. Digestion was monitored by SDS-PAGE in conjunction with Coomassie staining and immunoblotting using rabbit antisera and human IgE.ResultsAt pH 4.0 and at PPR 0.1 most proteins, both allergen and non-allergen, were highly resistant to pepsin. Under conditions known to favor pepsin proteolysis, the established major allergens Ara h 2, Pru p 3 and Pen a 1 were highly resistant to proteolysis, while the allergen Cyp c 1 was not. However, this resistance to pepsin digestion only made Ara h 2 and to a lesser extent Pen a 1 and Pru p 3 stand out compared to their non-allergenic counterparts. Largely irrespective of preceding pepsin digestion conditions, pancreatin digestion was very effective for all tested proteins, allergens and non-allergens, except for Cyp c 1 and bovine collagen.ConclusionsSub-optimal pH, low pepsin-to protein ratio, and sequential pepsin and pancreatin digestion protocols do not improve the predictive value in distinguish allergens from non-allergens. Digestion conditions facilitating such distinction differ per protein pair.

Exploration of Potentially Bioactive Peptides Generated from the Enzymatic Hydrolysis of Hempseed Proteins.

The seed of industrial hemp is an underexploited protein source. In view of a possible use in functional foods, a hempseed protein concentrate was hydrolyzed with pepsin, trypsin, pancreatin, or a mixture of these enzymes. A detailed peptidomic analysis using data-dependent acquisition showed that the numbers of peptides identified ranged from 90 belonging to 33 parent proteins in the peptic hydrolysate to 9 belonging to 6 proteins in the pancreatin digest. The peptic and tryptic hydrolysates resulted to be the most efficient inhibitors of 3-hydroxymethyl-coenzyme A reductase activity when tested on the catalytic domain of the enzyme. Using the open access tools PeptideRanker and BIOPEP, a list of potentially bioactive peptides was generated: the alleged activities included the antioxidant property, the glucose uptake stimulating activity, the inhibition of dipeptidyl peptidase-IV and angiotensin-converting enzyme I.

Biophysical and in vitro absorption studies of iron chelating peptide from barley proteins

Isothermal titration calorimetry (ITC) and tandem mass spectrometry (MS/MS) were used to study the interaction between Fe2+ and the heptapeptide (SVNVPLY) from barley protein hydrolysate under physiological pH. The peptide showed an ability to form complexes with Fe2+ spontaneously, with a binding constant reaching 107 L mol−1. Two peptide binding sites were identified and amino acid residues like Leu, Val, Pro and Tyr have been recognized as critical for iron coordination. The capacity for the heptapeptide and its shorter tripeptide analogue (VPL) to improve iron absorption was studied in vitro using Caco-2 cells. The cell uptake increased 4 times for the Fe2+–SVNVPLY complex after pepsin–pancreatin digestion compared to the iron sulfate salt. The ferritin formation in the Caco-2 cells was also significantly enhanced when iron was chelated to the peptides. This research suggests a potential application of barley peptides as dietary supplements to improve iron absorption.

Effect of heat and homogenization on in vitro digestion of milk

Central to commercial fluid milk processing is the use of high temperature, short time (HTST) pasteurization to ensure the safety and quality of milk, and homogenization to prevent creaming of fat-containing milk. Ultra-high-temperature sterilization is also applied to milk and is typically used to extend the shelf life of refrigerated, specialty milk products or to provide shelf-stable milk. The structures of the milk proteins and lipids are affected by processing but little information is available on the effects of the individual processes or sequences of processes on digestibility. In this study, raw whole milk was subjected to homogenization, HTST pasteurization, and homogenization followed by HTST or UHT processing. Raw skim milk was subjected to the same heating regimens. In vitro gastrointestinal digestion using a fasting model was then used to detect the processing-induced changes in the proteins and lipids. Using sodium dodecyl sulfate-PAGE, gastric pepsin digestion of the milk samples showed rapid elimination of the casein and α-lactalbumin bands, persistence of the β-lactoglobulin bands, and appearance of casein and whey peptide bands. The bands for β-lactoglobulin were eliminated within the first 15min of intestinal pancreatin digestion. The remaining proteins and peptides of raw, HTST, and UHT skim samples were digested rapidly within the first 15min of intestinal digestion, but intestinal digestion of raw and HTST pasteurized whole milk showed some persistence of the peptides throughout digestion. The availability of more lipid droplets upon homogenization, with greater surface area available for interaction with the peptides, led to persistence of the smaller peptide bands and thus slower intestinal digestion when followed by HTST pasteurization but not by UHT processing, in which the denatured proteins may be more accessible to the digestive enzymes. Homogenization and heat processing also affected the ζ-potential and free fatty acid release during intestinal digestion. Stearic and oleic acids were broken down faster than other fatty acids due to their positions on the outside of the triglyceride molecule. Five different casein phosphopeptide sequences were observed after gastric digestion, and 31 sequences were found after intestinal digestion, with activities yet to be explored. Processing affects milk structure and thus digestion and is an important factor to consider in design of foods that affect health and nutrition.

In Vitro Gastrointestinal Digestion Model to Monitor the Antioxidant Properties and Bioavailability of Phenolic Antioxidants from Elderberry

The sustainability of the elderberry antioxidants during gastrointestinal (GI) digestion was monitored using an in vitro GI digestion model involving pepsin digestion (to simulate gastric digestion) and pancreatin digestion (to simulate small intestine conditions). The potential bioavailability of elderberry antioxidants after GI digestion was further determined by employing a membrane model using dialysis tubing. Our results showed that simulated GI digestion significantly decreased 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity of the elderberry antioxidant extract, but had no effect on its total phenolic content (TPC) and oxygen radical absorbance capacity (ORAC) value. After GI digestion, more than 75% of phenolic content in the elderberry extract was absorbable according to our simulated dialysis experiment. The impact of GI digestion on individual antioxidants in the elderberry extract was determined by reverse-phase high performance liquid chromatography (HPLC). Ten individual antioxidants were identified and quantified by HPLC with chlorogenic acid, rutin, catechin, p-coumaric acid, and quercetin as the major phenolic compounds in the elderberry extract. GI digestion increased the concentrations of chlorogenic acid and p-coumaric acid but decreased epicatechin and quercetin 3-glucoside content in the elderberry extract.

Salmon Protamine Decreases Serum and Liver Lipid Contents by Inhibiting Lipid Absorption in an In Vitro Gastrointestinal Digestion Model and in Rats.

Protamine has been used as an antiheparin drug and a natural preservative in various food products. However, limited studies have evaluated the physicochemical and functional properties of protamine. Hence, we assessed the mechanisms underlying the inhibition of lipid absorption following salmon protamine intake in in vitro and in vivo studies. In initial experiments, a salmon protamine hydrolyzate (PH) was prepared using in vitro simulated gastrointestinal digestion suppressed pancreatic lipase activity and micellar cholesterol solubility. This PH had higher bile acid-binding capacity and emulsion breakdown activity than casein hydrolyzate and l-arginine. However, the hypolipidemic functions of protamine were dramatically reduced by pancreatin digestion. In further experiments, groups of male Wistar rats were fed an AIN-93G diet containing 5% (wt/wt) salmon protamine or a protamine amino acid mixture. After 4 wk of feeding with experimental diets, reductions in serum and liver triacylglycerol (TAG) and cholesterol contents were observed in the presence of protamine, reflecting inhibition of TAG, cholesterol, and bile acid absorption. These data suggest that the formation of insoluble PH-bile acid complexes is critical before the bile acid-binding capacity is reduced. Therefore, dietary salmon protamine may ameliorate lifestyle-related diseases such as hyperlipidemia and obesity.

The total antioxidant capacity, total phenolics content and starch hydrolase inhibitory activity of fruit juices following pepsin (gastric) and pancreatin (duodenal) digestion

The objective of the study was to evaluate the stability of the antioxidant activity, total phenolics content and starch hydrolase inhibitory activities of 22 commercially available fruit juices using an in vitro digestion model. These are important parameters as far as consumers are concerned due to their associated therapeutic properties. The Oxygen Radical Absorbance Capacity (ORAC) assay, Ferric Reducing Antioxidant Power (FRAP) and the 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging assays as well as the inhibition of α-amylase and α-glucosidase were carried out. All 22 fruit juices were a significant source of polyphenols with values varying between 235 and 389 μg gallic acid equivalents per mL. Twelve out of the 22 juices showed a statistically significant increase (P < 0.05) in polyphenol content following the duodenal phase of digestion. ORAC values correlated better with the total phenolics content (R 2 = 0.975) as compared with FRAP (R 2 = 0.893), DPPH (R 2 = 0.821) and ABTS (R 2 = 0.752). IC50 values of the α-amylase inhibitory activity kept increasing following both digestion phases, indicating the reduced ability of the juices to inhibit this enzyme. However, the IC50 values of the α-glucosidase inhibitory activity kept decreasing, indicating a better efficacy to inhibit this enzyme. Overall, all fruit juices were observed to be a significant source of antioxidants with starch hydrolase inhibitory properties.

Novel semisolid SNEDDS based on PEG-30-di-(polyhydroxystearate): Progesterone incorporation and in vitro digestion

The aim of this work is to study the digestibility of PEG-30-di-(polyhydroxystearate) (Cithrol® DPHS) and its semisolid novel self-nanoemulsifying drug delivery systems (SNEDDS). Furthermore, the SNEDDS-mediated solubility enhancement of the poorly water-soluble drug Progesterone was evaluated in different media. Additionally, the impact of digestion on Progesterone solubilization was investigated in vitro by a pancreatin digestion assay. The Progesterone-loaded semisolid self-nanoemulsifying formulation (F2) was comprehensively characterized by photon correlation spectroscopy (PCS), differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD) and Fourier transform infrared spectroscopy (FTIR). SNEDDS were able to enhance the equilibrium solubility of Progesterone at various media. Only a minor part of Cithrol® DPHS was digested by pancreatin (less than 6%). Furthermore, protection of Progesterone against digestion-mediated precipitation was observed. Therefore, DPHS containing SNEDDS are attractive candidates for the development of bio robust drug delivery systems for the oral delivery of poorly soluble drugs.

Validation of an in vitro method for the estimation of apparent total tract digestibility of phosphorus in plant feed ingredients for pigs

The aim of this study was to validate an enzymatic in vitro method that estimates the apparent total tract digestibility (ATTD) of phosphorus (P) in feed ingredients from plant origin used in pig nutrition. Sixteen individually housed castrated male pigs (19.5±2.9kg) were fed a semisynthetic diet, either alone (control) or containing: wheat, barley, maize, potato protein concentrate, soybean expeller or rapeseed expeller for periods of 14 days. The ATTD of P was determined indirectly using celite as a marker. The in vitro released P was determined after three consecutive steps: preliminary soaking in acid medium, pepsin digestion in strong acid medium and pancreatin digestion in neutral medium. The in vivo ATTD of P were 0.21, 0.37, 0.48, 0.41, 0.33 and 0.39 in the respective feed ingredients as listed above. The in vivo ATTD of P and the in vitro released P were linearly correlated (in vitro released P=−0.118 (P>0.10)+1.171 (P<0.01)×in vivo ATTD of P, R2=0.91). Thus, the in vitro method was successful in predicting in vivo ATTD of P in the plant feed ingredients tested here. The in vitro method can be proposed as an inexpensive tool to rapidly estimate ATTD of P in plant feed ingredients.

Identification of ace-inhibitory peptides from squid skin collagen after in vitro gastrointestinal digestion

Collagenous residues from squid skins were hydrolysed with Esperase and fractionated into three different peptide fractions (10–3kDa, F1; 3–1kDa, F2; <1kDa, F3). The lowermost molecular weight fraction (F3) showed the highest ACE inhibitory capacity. The effect of simulated in vitro gastrointestinal digestion on ACE-inhibitory activity of these three peptide fractions was evaluated. For this purpose, the fractions were hydrolysed with pepsin (F1G, F2G and F3G) followed by pancreatin (F1GI, F2GI and F3GI). Pepsin digestion hardly modified the molecular weights distribution of the peptide fractions. However, digestion with pepsin followed by pancreatin gave an increase in low molecular weight peptides. The pepsin–pancreatin digestion increased the ACE-inhibitory capacity of F1 (F1GI) and especially of F3 (F3GI). A new decapeptide (Gly-Arg-Gly-Ser-Val-Pro-Ala-Hyp-Gly-Pro) with potent ACE-inhibitory capacity (IC50 47.78μM) was identified from the digested fraction F3GI, using liquid chromatography, isoelectric focusing and tandem mass spectrometry. The potential antihypertensive effect of the <1kDa fraction from squid skin hydrolysate is reasonably high and could be improved after gastrointestinal digestion.

Antioxidant Effect and Water-Holding Capacity of Roselle (&lt;em&gt;Hibiscus sabdariffa L.&lt;/em&gt;) Seed Protein Hydrolysates

The aim of this study was to investigate the effect of <em>in</em>-vitro pepsin and pancreatin digestion of proteins extracted from Roselle seed on the production of bioactive peptides. Defatted Roselle seed flour was used to extract different protein fractions namely globulin, albumin and glutelin. The proteins were digested using pepsin (1 h) followed by pancreatin (1 h) in order to produce hydrolysates with good antioxidant activity. The prepared hydrolysates were as effective as antioxidants in model systems, in scavenging of free radicals and acting as reducing agents. This effect was concentration-dependent and was also influenced by the type of protein fraction. The albumin fraction hydrolysates prepared showed the highest antioxidant activity followed by Glutelin and Globulin hydrolysates respectively (Albumin hydrolysates>Glutelin hydrolysates>Globulin hydrolysates). All of the prepared hydrolysates were also found to be effective in enhancing water-holding capacity and cooking yield in a meat model system. Albumin hydrolysates showed the highest improved meat cooking ability followed by Glutelin and Globulin respectively (Albumin hydrolysates>Glutelin hydrolysates>Globulin hydrolysates). The molecular weight distribution analysis of the hydrolysates was determined and most of the peptides were found between 1000 Da and below. The study findings suggest that Roselle seed protein hydrolysates can be applied as functional food ingredients and that their composition determines their functional properties thus their potential application in the food and feed industries.

Effect of citric acid deamidation on in vitro digestibility and antioxidant properties of wheat gluten

The effects of citric acid deamidation on the physiochemical properties of wheat gluten were investigated. In vitro digestion was carried out to determine changes of molecular weight distribution, amino acids composition and antioxidant efficacy of wheat gluten hydrolysates. Results indicated that citric acid deamidation significantly increased gluten solubility and surface hydrophobicity, at a neutral pH. Deamidation induced molecular weight distribution change of gluten with little proteolysis. Results from FTIR indicated that the α-helix and β-turn of deamidated gluten increased accompanied by a decrease of the β-sheet structure. After deamidation, in vitro pepsin digestibility of wheat gluten decreased, while in vitro pancreatin digestibility increased. The oxygen radical absorbance capacity (ORAC) activity of the in vitro digests decreased with increase of deamidation time. The high Lys and total essential AAs amounts in the final digests suggested that the nutritional values of wheat gluten after deamidation might be enhanced.

In Vitro Antioxidant Activities of Protein Hydrolysate from Germinated Black Soybean (&lt;em&gt;Glycine max&lt;/em&gt; L.)

During this study, the effect of germination in combination with in vitro pepsin and pancreatin digestion of protein flours extracted from black soybean on the production of bioactive peptides was investigated. Black soybean (Glycine max L.) were germinated for 3 days (at 24, 48 and 72 h, respectively germination periods) and harvested. Protein hydrolysates from germinated black soybean were prepared from protein isolate by in vitro digestion using pepsin and pancreatin and then evaluated for antioxidant activity. Soy protein hydrolysate from 48 h of germination exhibited the highest scavenging activity against 2, 2-Diphenyl-1-Picrylhydrazyl (DPPH) free radicals (76.56 % at 2.5 mg/mL) followed by 24 and 72 h (66.62 and 60.55% at 2.5 mg/mL, respectively). Protein hydrolysate from germinated black soybean also exhibited noticeable scavenging activity for hydroxyl. Soy protein hydrolysate from 48 h of germination (97.475% at 2 mg/mL) significantly was the most effective in neutralizing •OH (p<0.05) than that from 24 and 72 h (88.56 and 92.5%, respectively at 2 mg/mL), compared to the nongerminated which was 34.42% also at the same concentration. In addition, soyprotein hydrolysate from 24 h of germination significantly showed the highest reducing power (0.32 at 2.0 mg/mL) compared to that from 48 and 72 h germination period (0.25 and 0.23 at 2.0 mg/mL, respectively). Molecular Weights distribution of protein hydrolysates from germinated black soybean was believed to have correlation with their antioxidant activities. Results showed that germination with in vitro digestion (pepsin and pancreatin) of protein hydrolysate from germinated black soybean was successful in production of natural antioxidant compounds which established obvious antioxidant potency than non-germinated. As conclusion, soy protein hydrolysate from 48 h of germination had the best antioxidant potency and could be used as natural antioxidant in food systems.

Application of chromatography and mass spectrometry to the characterization of cobalt, copper, manganese and molybdenum in Morinda Citrifolia

An analytical procedure was proposed to determine the manganese species and to study the fractionation of microelements such as copper, cobalt and molybdenum in Noni juice. Morinda citrifolia is known as a noni fruit, Indian mulberry, nunaakai, dog dumpling, mengkudu, beach mulberry, vomit fruit and cheese fruit. It is a tropical plant with a long tradition of medicinal use in Polynesia and tropical parts of eastern Asia and Australia. This article covers the determination of manganese species in Noni juice and established by fractionation by size exclusion chromatography inductively coupled plasma mass spectrometry (SEC ICP MS) and next characterization of species by electrospray ionization mass spectrometry (ESI MS). Also presented the fractionation analysis of copper, cobalt and molybdenum in Noni juice sample using SEC ICP MS – juice was treated with buffer and enzymatic extraction media and analyzed. For the evaluation of the amounts of the metal fractions distinguished, the ICP MS was used off-line prior to the determination of copper, cobalt, molybdenum and manganese concentrations in the juice. It was established that elements are present in the analyzed samples in different species and their concentration is μgmL−1 and ngmL−1 range in fruit. The accuracy of the entire fractionation scheme and sample preparation procedures involved was verified by the performance of the recovery test. For the information about the bioavailability of these elements, in vitro bioavailability investigation was used by SEC ICP MS technique. Two step digestion model simulating gastric (pepsin digestion) and intestinal (pancreatin digestion) juices. In Noni juice, manganese is complexed from flavonoids – rutin, from dye like anthraquinone (alizarin) and glycosides – asperulosidic acid (ESI MS – characterization). The study shows that copper and molybdenum contained in Noni juice are complexed by peptides, and cobalt by organic acids (which are 3.6% of juice). Molybdenum in the sample is also bound by the polysaccharides (SEC ICP MS). In addition, compounds complexing manganese, copper and molybdenum are hydrophobic proteins.

Variation of in situ rumen degradation of crude protein and amino acids and in vitro digestibility of undegraded feed protein in rapeseed meals

In this study, 10 samples of rapeseed meal (RSM) from 10 different oil plants in Germany were examined. In situ rumen degradation of CP was determined by incubation over 1, 2, 4, 8, 16, 32 and 72 h in duplicate per time point using three rumen fistulated dry cows. Degradation kinetics were estimated by an exponential model and effective CP degradation was calculated. Degradation was corrected for small particle loss as the difference between washing loss and water-soluble fraction. Amino acid analysis was carried out in the samples and in the residues after 8 and 16 h of incubation in situ and degradation of individual amino acids was calculated for these incubation times. In vitro pepsin–pancreatin digestibility of CP (IPD) was determined in the samples as well as in the 8 and 16 h residues. Effective CP degradation for a rumen outflow rate of 8%/h (ED8) averaged 54.3% with a considerable variation among samples ranging from 44.3% to 62.7%. A multiple regression equation containing acid detergent insoluble N, total glucosinolates and petroleum ether extract as independent variables predicted ED8 with satisfying accuracy (R2 = 0.74; RSD = 6.4%). Degradation of amino acids was different from that of CP for most amino acids studied, especially after 8 h of incubation. Compared with CP, degradation of essential amino acids was predominantly lower while degradation of non-essential amino acids was higher in most cases. However, for lysine and methionine no distinct difference with CP degradation was found. Degradation of individual amino acids was predicted from CP degradation with high accuracy using linear regression equations. Average IPD of RSM was 79.8 ± 2.6%. IPD was lower in the incubation residues and decreased with longer incubation time and increasing rumen degradation, respectively.

Binding affinity between dietary polyphenols and β-lactoglobulin negatively correlates with the protein susceptibility to digestion and total antioxidant activity of complexes formed

Non-covalent interactions between β-lactoglobulin (BLG) and polyphenol extracts of teas, coffee and cocoa were studied by fluorescence and CD spectroscopy at pH values of the gastrointestinal tract (GIT). The biological implications of non-covalent binding of polyphenols to BLG were investigated by in vitro pepsin and pancreatin digestibility assay and ABTS radical scavenging activity of complexes formed. The polyphenol–BLG systems were stable at pH values of the GIT. The most profound effect of pH on binding affinity was observed for polyphenol extracts rich in phenolic acids. Stronger non-covalent interactions delayed pepsin and pancreatin digestion of BLG and induced β-sheet to α-helix transition at neutral pH. All polyphenols tested protected protein secondary structure at an extremely acidic pH of 1.2. A positive correlation was found between the strength of protein–polyphenol interactions and (a) half time of protein decay in gastric conditions (R2=0.85), (b) masking of total antioxidant capacity of protein–polyphenol complexes (R2=0.95).

Extraction, isolation and analysis of chondroitin sulfate from broiler chicken biomass

This study was undertaken to investigate whether chondroitin sulfate (CS) can be efficiently isolated from broiler chicken by-product from mechanical deboning (BMD), which is a mixture of crushed bone, cartilage, skin, adipose tissue and muscle. With BMD as a starting material, it may be possible to maximize CS production from chicken cartilage. CS was liberated from BMD by proteolysis using proteolytic activities from papain, pancreatin, kiwi fruits and flavourzyme. The final product isolated by anion-exchange chromatography and differential precipitation with varying concentrations of ethanol contained CS-peptides with glucuronosyl-N-acetylgalactosamine-4-sulfate as a predominant disaccharide. All the enzyme sources used had sufficient activities to produce CS-peptides with undetectable amount of glucosamine. However, the size of peptide attaching to CS chain and the antigenicity to anti-keratan sulfate (KS) monoclonal antibody varied among the CS-peptides prepared with different proteinases. Papain digestion resulted in the smallest size of peptide with no detectable antigenicity to the anti-KS antibody. In contrast, pancreatin digestion provided CS-peptide having a very weak but positive antigenicity to the anti-KS antibody, which was much lower than that seen with CS-peptide prepared with kiwi fruit proteinase or flavourzyme. Pancreatin is suggested as an economical source of proteinase to liberate CS-peptides from BMD.

Investigation of iodine bioavailability from chicken eggs versus iodized kitchen salt with in vitro method

The goal of the presented studies was to investigate speciation and bioavailability of iodine from chicken eggs versus iodized kitchen salt with an in vitro method. Determination of iodine total content in chicken eggs and iodized kitchen salt was carried out by inductively coupled plasma mass spectrometry (ICP MS). The majority of iodine was accumulated in the yolk—the concentration was even 37 times higher than in white. Chicken eggs were treated with buffer (Tris HCl pH = 7.5) and enzymatic extraction media and analyzed by size exclusion chromatography hyphenated with inductively coupled plasma mass spectrometry (SEC ICP MS). The enzymatic extraction being an in vitro bioavailability assessment method was based on two-stage digestion model simulating gastric (pepsin digestion) and intestinal (pancreatin digestion) juices. Speciation analyses along with bioavailability studies presented iodide as the major form in chicken eggs. The bioavailability was established as 33% from white and 10% from yolk and decreased with longer time of boiling. It allows to suggest that the majority of iodine remains in forms bound to non-digestible coagulated and water-insoluble proteins.

Design of substrate-type ACE inhibitory pentapeptides with an antepenultimate C-terminal proline for efficient release of inhibitory activity

Much research has verified that tripeptides initiated with a branched-chain aliphatic amino acid residue and terminated with a proline have a strong antihypertensive activity in vivo. However, it is difficult to release from their precursor proteins that are orally administered. Based on the selectivity of angiotensin I-converting enzyme (ACE) on C-terminal dipeptides in its substrate, six pentapeptides with the same tripeptide IKP (as a model) at N-terminus including IKPVQ, IKPVA, IKPVK, IKPVR, IKPFR, and IKPHL were designed and chemically synthesized. It was shown that all the pentapeptides released IKP after ACE incubation. The release rate ranged from 23% (IKPHL) to 84.6% (IKPVR) as compared to the peptide sample before incubation. The in vitro digestion experiment demonstrated that all of the pentapeptides except IKPVA with a retention rate of 80.5% were resistant to pepsin hydrolysis but not to pancreatic hydrolysis. It should be noted that IKP could be released from IKPFR by pancreatin digestion. These results suggest that IKPVA and IKPFR potentially have a great antihypertensive effect in vivo. Furthermore, the dipeptides VA and FR described here may be widely used as linkers to help the release of the active peptides with proline at C-terminus from their protein precursors by ACE or gastrointestinal enzymes in human body.