Pepsin Treatment Research Articles

Development of industrial ultrasound system for mass production of collagen and biochemical characteristics of extracted collagen

Collagen is a widely used material in food and cosmetic products, but it has high price because of complicated extraction process and low yields. In order to overcome these problems, a mass production system of collagen from fish skin has developed using an industrial scale of ultrasound extraction equipment. Collagen was extracted from flatfish skin using 0.05M acetic acid solution for a total of 3h in an ultrasound system and was collected by centrifugation. The collagen yields by this method were ∼31.3 and 46.2% after 1.5 and 3h, respectively, which were 1.5 and 2 times higher than those by the conventional method. The pepsin digestibility was examined to confirm whether the extract was native collagen. Despite pepsin treatment, the α1 (α3), α2, β chains of the collagen extracted by the industrial ultrasound system did not change, whereas gelatin were degraded almost completely and low molecular weight components were increased. In addition, the amino acid analysis result showed that the extract contained high contents of glycine, proline, and hydroxyproline, indicating that the extract has a typical collagen composition. Therefore, it was confirmed that the component extracted by the industrial ultrasonic system was native collagen.

Plastein reaction enhanced bile-acid binding capacity of soybean protein hydrolysates and whey protein hydrolysates

Plastein reaction is a modification reaction that can improve the functional properties of protein hydrolysate. The product of the reaction is a thixotropic aggregation of peptides. This study investigated the formation condition of soybean-whey plastein and bile acid binding capacity of plastein. Soy protein and whey protein were hydrolyzed by pepsin. The mixture (1:1, w/w) of two hydrolysates was modified by pepsin again. After the reaction, the decrease in free amino groups and the turbidity of the modified hydrolysate were measured to obtain appropriate reaction condition. Results showed that the concentration of hydrolysates 40% (w/v), enzyme ratio of 2.0KU/g protein, pH 5.0, 37°C, reaction time of 3.0h respectively, were showed maximum changes in protein hydrolysates. Tricine SDS-PAGE analysis under denaturing conditions revealed that whey protein was more sensitive to pepsin and yielded different polypeptides (PPs) of molecular weight ranged from 3.5-17 kDa. However, a high molecular weight PP was completely hydrolyzed while PPs of 14.2-26 kDa were partially digested after pepsin treatment. Native page analysis further revealed the presence of a high-molecular weight PP in crude and purified plastein product. The bile acid binding capacity was improved by the plastein reaction. The amount of binding sodium deoxycholate, sodium taurocholate, and sodium cholate were 0.75, 2.0 and 1.87μmol/100mg respectively.

Changes in structure and antioxidant activity of β-lactoglobulin by ultrasound and enzymatic treatment

Effects of ultrasound (20–40% amplitudes at 45–55 °C) and enzymatic (pepsin and trypsin) treatment on structure and antioxidant activity of β-lactoglobulin were studied. Changes in structure of β-lactoglobulin were investigated using spectroscopy techniques and changes in antioxidant activity were measured by chemical and cellular-based assays. Ultrasound treatment had considerable impact on the structure of β-lactoglobulin and increased the susceptibility of β-lactoglobulin to both pepsin and trypsin proteolysis. Intrinsic fluorescence intensity of β-lactoglobulin was increased by ultrasound and then decreased after following enzymatic treatment. Compared with control, the β-lactoglobulin after ultrasound and enzymatic treatments showed significantly higher oxygen scavenging activities in Caco-2 cells models, ABTS (2, 2′-Azinobis-3-ethylbenzthiazoline-6-sulphonate) radical scavenging activity and oxygen radical absorbance capacity (p < 0.05). Results indicated that ultrasound treatment increased the proteolysis of β-lactoglobulin by both pepsin and trypsin and improved the antioxidant activity of the protein and its proteolytic products.

Evaluation of aging, diabetes mellitus, and skin wounds by scanning acoustic microscopy with protease digestion.

ABSTRACTScanning acoustic microscopy (SAM) can assess tissue stiffness by calculating the speed of sound (SOS) through tissues. SOS increases as tissue stiffness increases. Sensitivity to protease digestion depends on protein type, concentration, and modification. We analyzed the SOS images of formalin-fixed paraffin-embedded skin sections from elderly, young, diabetic, and nondiabetic subjects, as well as chronic and acute wounds. SAM provided high-resolution histology similar to LM and revealed characteristic SOS alteration following pepsin treatment. SOS values of dermis samples from elderly subjects (especially females) were lower than those of younger adults, which was indicative of age-related dermal softening and loosening. SOS values of elderly females were lower than those of younger females and elderly males. Dermal SOS showed a positive correlation with epidermal thickness. SOS values of epidermis of elderly subjects were higher than those of younger adults and showed a rapid decline 0.5h after protease digestion. Reticular dermis of diabetic patients exhibited greater pepsin resistance than that of nondiabetic patients. Chronic wounds exhibited greater SOS values and pepsin resistance than acute wounds. SOS variation with aging, diabetes mellitus, and wound fibrosis reflected histological and mechanical changes associated with senescence and disease duration. Epidermal thickness reflects age-related changes in dermal stiffness.

In vitro protein digestion of pork cuts differ with muscle type

Porcine trapezius, longissimus dorsi and biceps femoris muscles have been shown to contain different types of muscle fibers. Little is known about the differences in digestibility among cooked pork cuts. In this study, we compared the protein losses of porcine trapezius, longissimus dorsi and biceps femoris muscles under in vitro digestion conditions. Meat samples were cooked in 72°C water bath to center temperature of 70°C. Then meat samples were homogenized and incubated with pepsin alone or followed by trypsin. The in vitro protein losses and particle size were measured. The pepsin and trypsin digestion products were separated and identified by SDS-PAGE and Nano LC-LTQ-Orbitrap XL MS/MS. The results indicated that longissimus dorsi muscle had the highest losses under both pepsin and trypsin treatments (P<0.05). In untreated samples, biceps femoris muscle showed the greatest particle size (P<0.05), but enzymatic treatment decreased particles to the similar size for all the three muscles (P>0.05). Proteome analysis indicated that biceps femoris muscle had the highest susceptibility to digestion. Interaction analysis reveals that differential proteins mainly are related to glycolysis and muscle contraction. And thus fiber types could be the key factor to cause the differences in protein composition and their susceptibility to digestion.

Stability of Angiotensin I-converting Enzyme Inhibitory Activity of Peptides Extracted from Dry-cured Jinhua Ham

Angiotensin I-converting enzyme (ACE) inhibitory activity of peptides extracted from traditional dry-cured Jinhua ham was investigated. The ACE-inhibitory activity was measured after the treatments of heat, NaCl, pH and simulated gastro-intestinal digestion. Peptides possessed an ACE-inhibitory activity of 53.53% at 10 mg/mL and showed a good stability against different heating temperatures (up to 100°C), heating times (up to 60 min) and acid conditions. The NaCl had no significant effects on the ACE-inhibitory activity, while there was a sharp decline under alkaline condition. The ACE-inhibitory activity increased by 4.01% after pepsin treatment and then remained constant after trypsin treatment. The increased ACE-inhibitory activity after pepsin digestion could be explained by the greater exposure of hydrophobic residues. In this study, peptides extracted from Jinhua ham were proved to have ACE-inhibitory activity which showed a good stability against various processing conditions as well as the simulated gastro-intestinal digestion.

Transforming Chicken Feather Waste into Feather Protein Hydrolysate Using a Newly Isolated Multifaceted Keratinolytic Bacterium Chryseobacterium sediminis RCM-SSR-7

Accumulation of feather waste is becoming a major issue in solid waste management. Towards discovery of keratinolytic bacteria, screening of bacterial strains from feather dumping sites in North East, India was performed and 26 keratinolytic bacterial strains were isolated. Out of these, one isolate RCM-SSR-7 was found to be most promising strain exhibiting feather degradation as well as antioxidant and indole-3-acetic acid production. The strain was identified as Chryseobacterium sediminis RCM-SSR-7. The strain could use chicken feather as sole carbon and nitrogen source for growth. Three parameters (feather concentration, pH and incubation time) were studied to optimize feather protein hydrolysate (FPH) preparation using response surface methodology (RSM). The optimum condition for FPH preparation was achieved at 5% (w/v) feather concentration, pH 7.5, 30 °C and 84 h incubation time upon optimization by RSM. FPH was found to be rich in essential amino acids and trace elements (phosphorous, potassium, calcium, and iron). FPH exhibited radical scavenging activity with an IC50 value of 0.102 mg ml−1. In vitro digestibility showed that FPH is 86% digestible with pepsin and trypsin treatment. This study revealed that FPH produced by C. sediminis RCM-SSR-7 has the potential to be used as animal feed and organic fertilizer.

Stability of antioxidant peptides from duck meat after post‐mortem ageing

SummaryThe stability of antioxidant peptides from aged duck meat during processing and simulated gastrointestinal digestion was investigated. The antioxidant peptides preserved a high stability in the presence of diverse NaCl or upon various time heating. The antioxidant activities were strengthened by the addition of 4–8% glucose or by heating at 100 °C, whereas they were lost under alkaline conditions. During in vitro digestion, the antioxidant activities increased with pepsin treatment but then decreased following trypsin digestion. Pepsin hydrolysed peptides into short fragments and results in the increased exposure of internal hydrophobic amino acids. With further treatment by trypsin, peptides can be hydrolysed completely and more free amino acids were released, leading to the decline in surface hydrophobicity. These variations might be responsible for the change in antioxidant activity during in vitro digestion. The antioxidant peptides from aged duck with high stability can be used as functional food ingredients to improve human health.

Pepsin treatment of whey proteins under high pressure produces hypoallergenic hydrolysates

Abstract BALB/c mice were used to assess the ability of a whey protein hydrolysate obtained by pepsin treatment under high pressure (400 MPa, 37 °C, 30 min, HWP), to induce anaphylaxis, antibody production and cytokine responses in comparison with the whey protein isolate (WP) from which it is derived. HWP did not contain intact allergens and 50% of its peptides ranged between 10 and 3 kDa. Challenge with HWP did not induce clinical signs, body temperature changes or release of mast cell proteinase-1 in mice sensitized to WP. Immunization of mice with HWP did not produce WP-specific antibodies or allergic reactions upon HWP or WP challenge and thus, it can be considered hypoallergenic. However, HWP stimulated Th2 responses in splenocytes from sensitized mice. These characteristics make HWP a good candidate to be used in the management of milk allergy in diagnosed patients or to induce tolerance to whey proteins. Industrial relevance Hydrolysis with pepsin under high pressure produces in minutes a whey protein hydrolysate that complies with the health claims of the European guidelines on infant and follow-on formulas related to the reduction of risk to allergy to milk proteins. This process constitutes an alternative to the exhaustive enzymatic hydrolysis treatments used in the processing of hypoallergenic formulas that release short peptides and free amino acids to adversely affect organoleptic properties and technological value.

Extraction and characterization of gelatin from the feet of Pekin duck (Anas platyrhynchos domestica) as affected by acid, alkaline, and enzyme pretreatment

The effects of different pretreatments on yield and composition of extraction, physicochemical, and rheological properties of duck feet gelatin (DFG) were investigated. Gelatins were extracted from the whole feet of Pekin duck with an average yield of 4.09%, 3.65%, and 5.75% for acidic (Ac-DFG), alkaline (Al-DFG), and enzymatic (En-DFG) pretreatment on a wet weight basis, respectively. Proteins at 81.38%, 79.41%, 82.55%, and 87.38% were the major composition for Ac-DFG, Al-DFG, En-DFG, and bovine, respectively. Amino acid analysis showed glycine as the predominant amino acid in Ac-DFG, followed by hydroxyproline, proline, and alanine for Ac-DFG, Al-DFG, and En-DFG, respectively. Rheological analysis indicated that the maximum elastic modulus (9972.25Pa) and loss modulus (4956.28Pa) for Ac-DFG gelatin were significantly higher than those of other gelatins. Extracted gelatins contained α1 and α2 chains as the predominant components, and enzymatic gelatin had low molecular weight peptides. Fourier transform infrared spectroscopy showed that the peak of the gelatins was mainly positioned in the amide band region (amides I, II, and III). A considerable loss of molecular-order triple helical structure was also observed after pepsin treatment. In summary, duck feet gelatin has potential to replace as mammalian gelatin in food and pharmaceutical industry.

Biological potency and characterization of antibacterial substances produced by Lactobacillus pentosus isolated from Hentak, a fermented fish product of North-East India.

Lactic acid bacteria (LAB) isolated from various foods are important due to their potential to inhibit microorganisms, including drug-resistant bacteria. The objectives of this investigation were to isolate and identify antibacterial substances producing LAB from Hentak, a traditional fermented fish product of Manipur (North-East India), and to optimize the production of antagonistic substances present in cell free neutralized supernatant (CFNS) against enteric bacterial pathogens using the ‘one factor at a time’ (OFAT) method. Out of 10 LAB, the most potent bacterium producing antibacterial substances was isolated and identified as Lactobacillus pentosus strain LAP1 based upon morphological, biochemical and molecular characterization. MRS (de Man, Ragosa and Sharpe) medium was determined to provide better bactericidal activity (AU/ml) than other tested media against the indicator enteric bacteria, including Staphylococcus epidermidis MTTC 3615, Micrococcus luteus MTCC 106, Shigella flexneri MTCC 1457, Yersinia enterocolitica MTCC 840 and Proteus vulgaris MTCC 1771. The culture conditions (pH: 5, temperature: 30 °C and inoculum volume: 1 %) and medium components (carbon source: lactose and nitrogen source: ammonium chloride) were observed to be the most influential parameters of significant antagonistic activity of CFNS against the enteric pathogens. MRS medium supplemented with Tween20 effectively stimulated the yield of antibacterial substances. The CFNS of strain LAP1 exhibited sensitivity to proteolytic enzyme (pepsin) treatment and heat treatment (60 °C for 60 min, 100 °C for 30 min and 121 °C for 15 min) and lost its inhibitory properties. The CFNS was active at an acidic (pH 3.0) to neutral pH (pH 7.0) but lost its antagonistic properties at an alkaline pH. The CFNS obtained from strain LAP1 scavenges the DPPH (1,1-diphenyl-2 picrylhydrazyl) significantly in a concentration-dependent manner within the range of 8.8 ± 0.12–57.35 ± 0.1 %. The OFAT-based approach revealed the baseline for statistical optimization, the scale-up process and efficient production of CFNS by L. pentosus strain LAP1, which could be used as a potential antibacterial and free radical scavenging agent.

Control of foreign polypeptide localization in specific layers of protein body type I in rice seed.

Key messageProlamin–GFP fusion proteins, expressed under the control of native prolamin promoters, were localized in specific layers of PB-Is. Prolamin–GFP fusion proteins were gradually digested from outside by pepsin digestion.In rice seed endosperm, protein body type I (PB-I) has a layered structure consisting of prolamin species and is the resistant to digestive juices in the intestinal tract. We propose the utilization of PB-Is as an oral vaccine carrier to induce mucosal immune response effectively. If vaccine antigens are localized in a specific layer within PB-Is, they could be protected from gastric juice and be delivered intact to the small intestine. We observed the localization of GFP fluorescence in transgenic rice endosperm expressing prolamin–GFP fusion proteins with native prolamin promoters, and we confirmed that the foreign proteins were located in specific layers of PB-Is artificially. Each prolamin–GFP fusion protein was localized in specific layers of PB-Is, such as the outer-most layer, middle layer, and core region. Furthermore, to investigate the resistance of prolamin–GFP fusion proteins against pepsin digestion, we performed in vitro pepsin treatment. Prolamin–GFP fusion proteins were gradually digested from the peripheral region and the contours of PB-Is were made rough by in vitro pepsin treatment. These findings suggested that prolamin–GFP fusion proteins accumulating specific layers of PB-Is were gradually digested and exposed from the outside by pepsin digestion.

Angiotensin I Converting Enzyme Inhibitory Peptides Derived from Phycobiliproteins of Dulse Palmaria palmata.

We examined the inhibitory activity of angiotensin I converting enzyme (ACE) in protein hydrolysates from dulse, Palmaria palmata. The proteins extracted from dulse were mainly composed of phycoerythrin (PE) followed by phycocyanin (PC) and allophycocyanin (APC). The dulse proteins showed slight ACE inhibitory activity, whereas the inhibitory activity was extremely enhanced by thermolysin hydrolysis. The ACE inhibitory activity of hydrolysates was hardly affected by additional pepsin, trypsin and chymotrypsin treatments. Nine ACE inhibitory peptides (YRD, AGGEY, VYRT, VDHY, IKGHY, LKNPG, LDY, LRY, FEQDWAS) were isolated from the hydrolysates by reversed-phase high-performance liquid chromatography (HPLC), and it was demonstrated that the synthetic peptide LRY (IC50: 0.044 μmol) has remarkably high ACE inhibitory activity. Then, we investigated the structural properties of dulse phycobiliproteins to discuss the origin of dulse ACE inhibitory peptides. Each dulse phycobiliprotein possesses α-subunit (Mw: 17,477–17,638) and β-subunit (Mw: 17,455–18,407). The sequences of YRD, AGGEY, VYRT, VDHY, LKNPG and LDY were detected in the primary structure of PE α-subunit, and the LDY also exists in the APC α- and β-subunits. In addition, the LRY sequence was found in the β-subunits of PE, PC and APC. From these results, it was suggested that the dulse ACE inhibitory peptides were derived from phycobiliproteins, especially PE. To make sure the deduction, we carried out additional experiment by using recombinant PE. We expressed the recombinant α- and β-subunits of PE (rPEα and rPEβ, respectively), and then prepared their peptides by thermolysin hydrolysis. As a result, these peptides showed high ACE inhibitory activities (rPEα: 94.4%; rPEβ: 87.0%). Therefore, we concluded that the original proteins of dulse ACE inhibitory peptides were phycobiliproteins.

인간성대 섬유아세포주에서 Acid와 Pepsin의 효과

Background and Objectives: Laryngopharyngeal reflux, the backflow of gastric contents into the pharynx and larynx, is among the most important factors behind the development of inflammatory disorders of the upper airway. Our objective was to clarify the effects of exposure of the acid and pepsin in the laryngopharyngeal reflux disease by carrying out research on gene changes in the human vocal fold fibroblast. Material and Methods: To make a cell culture solution of acidic conditions of pH4 and 5 by using a 0.01 M hydrochloric acid. Pepsin was prepared in 0.5 mg/mL concentration dissolved in 0.9% sodium chloride. Pepsin was added to the cell culture fluid of pH4 and pH5 acid. The prepared acidic cell culture solution for each condition was treated for 5 minutes on the fibroblasts of the vocal folds. Then to remove the acidic cell culture solution, the vocal fold fibroblast culture fluid was incubated for 6 hours. After the culture, real time PCR, MTT assay and LDH assay were carried out. Results: The human vocal fold fibroblast in the pH4 acidic cell culture medium containing pepsin has the highest cell damage form. We confirmed these results by using the MTT assay and LDH assay. After incubation for 6 hours, it was confirmed that the cell was returned in the normal form of a vocal fold fibroblast in all experimental groups compared to the control groups. There are no significant differences of gene expression after acid and/or pepsin treatment in human vocal fold fibroblast. Conclusions: The most critical effect on the damage to the vocal fold cells was the interaction of pH4 acidic environment and pepsin than acting alone or pH5 environment. (J Clinical Otolaryngol 2015;26:236–242)

Process integration for recovery of recombinant collagen type I α1 from corn seed.

Because of safety concerns and product consistency issues with the use of animal-derived collagen, several recombinant protein expression hosts have been considered for recombinant collagen corn seed. Full length, triple-helical, recombinant collagen (rCIα1) is expressed as a fusion with a foldon domain, which must later be removed. Here we have examined integration of purification and foldon removal by comparing advantages of removal before or after purification, using salt precipitation as the main purification step. Because expression levels in available maize lines are low, Pichia-produced recombinant collagens, both with and without foldon, were added to corn seed germ at the extraction step. Salt precipitation of an acidic corn seed extract yielded 100% of the collagen without foldon at >70% purity without the pepsin pretreatment. With pepsin pretreatment, yield was 94.0% with purity of 76.5%. Analysis of the protein molecular weight distribution of the pre- and post-treatment extracts showed that the corn proteins are largely resistant to pepsin proteolysis, explaining why little benefit was obtained by pepsin treatment. In the absence of pepsin treatment, the recovery of rCIα1 with foldon was still above 90% but the purity was only 44%. This still represented at about 13-fold purification with a 2.7-fold volume reduction which would reduce the pepsin requirement for post-recovery foldon cleavage.

Effects of heat treatment on oil-binding ability of rice flour.

Heat-treated (120 °C for 120 min) rice flour showed high affinity to oil (oil-binding ability). This oil-binding ability could be observed by shaking the heat-treated rice flour (2.0 g), oil (4.0 mL), and water (20 mL) vigorously in a test tube, and the oil bound to the rice flour sank into the water. To examine the time-dependent levels of the oil-binding ability, rice flour was heat-treated at 120 °C for 10, 20, 40, 60, and 120 min, and the precipitated volume of oil/rice flour complex increased with an increase of the heating time. The oil-binding ability of the rice flour was not affected by the treatments with diethyl ether or boiled chloroform/methanol (2:1) solutions, which suggested no relationship to the oil in the rice flour, but was lost upon alkali (0.2% NaOH solution) or pepsin treatment, which suggested its relationship to the rice proteins.

Enzymatic hydrolysis of ovomucoid and the functional properties of its hydrolysates

Ovomucoid is well known as a “trypsin inhibitor” and is considered to be the main food allergen in egg. However, the negative functions of ovomucoid can be eliminated if the protein is cut into small peptides. The objectives of this study were to hydrolyze ovomucoid using various enzyme combinations, and compare the functional properties of the hydrolysates. Purified ovomucoid was dissolved in distilled water (20 mg/mL) and treated with 1% of pepsin, α-chymotrypsin, papain, and alcalase, singly or in combinations. Sodium sodium dodecyl sulfate-polyacrylamide (SDS-PAGE) results of the hydrolysates indicated that pepsin (OMP), alcalase (OMAl), alcalase + trypsin (OMAlTr), and alcalase + papain (OMAlPa) treatments best hydrolyzed the ovomucoid, and the 4 treatments were selected to determine their functional characteristics. Among the 4 enzyme treatments, hydrolysate from OMAlTr showed the highest iron-chelating and antioxidant activities, while OMP showed higher ACE-inhibitory activity, but lower Fe-chelating activity than the other treatments. However, no difference in the copper-chelating activity among the treatments was found. MS/MS analysis identified numerous peptides from the hydrolysates of OMAlPa and OMAlTr, and majority of the peptides produced were <2 kDa. Pepsin treatment (OMP), however, hydrolyzed ovomucoid almost completely and produced only amino acid monomers, di- and tri-peptides. The ACE-inhibitory, antioxidant and iron-chelating activities of the enzyme hydrolysates were not consistent with the number and size of peptides in the hydrolysates, but we do not have information about the quantity of each peptide present in the hydrolysates at this point.

The Bright Side of Gelatinous Blooms: Nutraceutical Value and Antioxidant Properties of Three Mediterranean Jellyfish (Scyphozoa).

Jellyfish are recorded with increasing frequency and magnitude in many coastal areas and several species display biological features comparable to the most popular Asiatic edible jellyfish. The biochemical and antioxidant properties of wild gelatinous biomasses, in terms of nutritional and nutraceutical values, are still largely unexplored. In this paper, three of the most abundant and commonly recorded jellyfish species (Aurelia sp.1, Cotylorhiza tuberculata and Rhizostoma pulmo) in the Mediterranean Sea were subject to investigation. A sequential enzymatic hydrolysis of jellyfish proteins was set up by pepsin and collagenase treatments of jellyfish samples after aqueous or hydroalcoholic protein extraction. The content and composition of proteins, amino acids, phenolics, and fatty acids of the three species were recorded and compared. Protein content (mainly represented by collagen) up to 40% of jellyfish dry weight were found in two of the three jellyfish species (C. tuberculata and R. pulmo), whereas the presence of ω-3 and ω-6 polyunsaturated fatty acids (PUFAs) was significantly higher in the zooxanthellate jellyfish C. tuberculata only. Remarkable antioxidant ability was also recorded from both proteinaceous and non proteinaceous extracts and the hydrolyzed protein fractions in all the three species. The abundance of collagen, peptides and other bioactive molecules make these Mediterranean gelatinous biomasses a largely untapped source of natural compounds of nutraceutical, cosmeceutical and pharmacological interest.

The Impact of Pepsin on Human Nasal Epithelial Cells In Vitro

To describe potential mechanisms by which pepsin induces inflammation in refractive chronic rhinosinusitis (CRS). Our hypothesis was that pepsin induces mitochondrial damage and cytokine expression in human nasal epithelial cells (HNEpC) in vitro. Western blot was used to detect pepsin in sinus lavages from patients with CRS and controls. The HNEpC cells were treated with pepsin (pH 7; 0.1 mg/mL) for 1 or 16 hours and routine electron microscopy (EM) and MTT assay were performed. Cytokine ELISA was performed on media collected from HNEpC cells 16 hours following a 1-hour pepsin treatment. Pepsin was detected in sinus lavages from 4 out of 6 CRS patients and 0 out of 3 controls. The EM showed mitochondrial damage in pepsin-treated HNEpC cells but not in control cells. The MTT assay demonstrated reduced mitochondrial activity in pepsin-treated HNEpC cells compared to controls (P < .001). Pepsin increased IL-1A (P = .003) and IL-6 (P = .04) expression in HNEpC cells. Pepsin in sinus lavages from patients with CRS is consistent with previous studies. This study reveals the damaging effect of pepsin on mitochondria in nasal epithelial cells in vitro. Cytokines previously associated with CRS were elevated following pepsin treatment of HNEpC cells in vitro. These results demonstrate mechanisms by which pepsin may potentiate CRS.

Influence of &lt;i&gt;In vitro&lt;/i&gt; Digestion on Antioxidative Activity of Coconut Meat Protein Hydrolysates

Purpose: To investigate the antioxidative stability of coconut meat protein hydrolysates (CMPHs) in the gastrointestinal tract, and evaluate the changes in antioxidant activity, amino acid composition and molecular weight distribution of CMPHs during gastrointestinal (GI )digestion Methods: A two-stage in vitro digestion model (pepsin treatment for 2 h followed by pancreatin treatment for 2 h, both at 37 °C) was used to simulate the process of GI digestion to determine changes in antioxidant activities, namely, 1,1- diphenyl-2-picrylhydrazyl and hydroxyl radical scavenging and reducing power, of CMPHs previously prepared by papain digestion. Results : Based on the in vitro pepsin–pancreatin simulated GI digestion, it was found that there were more free amino acids and smaller oligopeptides with MW < 500 Da in the final GI digests. Compared with blank, enzymatic breakdown of the GI digests increased their hydroxyl (by 11.8 %) and reducing power (by 71.8 %). Conclusion : CMPHs are high value-added antioxidants and possess a potential capacity to resist gastrointestinal digestion, which makes them promising ingredients for formulation of functional foods. Keywords: Coconut meat protein, Hydrolysates, Simulated gastrointestinal digestion, Antioxidativestability, Oligopeptides, Functional foods