Tartary buckwheat protein hydrolysates enhance the salt tolerance of the soy sauce fermentation yeast Zygosaccharomyces rouxii.

Supplementation of protein hydrolysate is an important strategy to improve the salt tolerance of soy sauce aroma-producing yeast. In the present study, Tartary buckwheat protein hydrolysates (BPHs) were prepared and separated by ultrafiltration into LM-1 (<1 kDa) and HM-2 (1-300 kDa) fractions. The supplementation of HM-2 fraction could significantly improve cell growth and fermentation of soy sauce aroma-producing yeast Zygosaccharomyces rouxii As2.180 under high salt (12%, w/w) conditions. However, the LM-1 fraction inhibited strain growth and fermentation. The addition of HM-2 promoted yeast cell accumulation of K+, removal of cytosolic Na+ and accumulation of glycerol. Furthermore, the HM-2 fraction improved the cell membrane integrity and mitochondrial membrane and decreased intracellular ROS accumulation of the strain. The above results indicated that the supplementation of BPHs with a molecular weight of 1-300 kDa is a potentially effective and feasible strategy for improving the salt tolerance of soy sauce aroma-producing yeast Z. rouxii.

Bioactive peptides attenuate cardiac apoptosis in spontaneously hypertensive rat hearts through activation of autophagy and mitochondrial biogenesis pathway.

Alcalase potato protein hydrolysate (APPH) might have a very important role in therapeutic effects. This study aims to examine the beneficial effects of bioactive peptides (DIKTNKPVIF [DI] and IF) from APPH supplement in the regulation of cardiac apoptosis, autophagy, and mitochondrial biogenesis pathway in spontaneously hypertensive rats (SHR). We have investigated ejection fraction, fractional shortening, Tunel assay, apoptosis, autophagy, and mitochondrial biogenesis pathway marker expression to show the efficacy of bioactive peptides in an SHR model. Bioactive peptides significantly upregulate ejection fraction and fractional shortening in SHR rats. SHR rats exhibited higher protein expression of apoptotic markers such as BAD, cytochrome c, and caspase 3. Finally, the bioactive peptides upregulate survival proteins (p-AKT/p-PI3K), autophagy (Beclin1/LC3B), and mitochondrial biogenesis (p-AMPKα/SIRT1/PGC1α/p-Foxo3a/Nrf2/CREB) marker expressions compared with the SHR groups. In summary, the bioactive peptides protect the heart tissues through the activation of autophagy and mitochondrial biogenesis pathway and thereby attenuate cardiac apoptosis in a spontaneously hypertensive rat model.

Transdermal permeation effect of collagen hydrolysates of deer sinew on mouse skin, ex vitro, and antioxidant activity, increased type I collagen secretion of percutaneous proteins in NIH/3T3 cells.

BACKGROUND: The collagen hydrolysates as a cosmetic material have already been wide application. At present, few studies concern with transdermal behavior of collagen hydrolysates in vitro. OBJECTIVE: Deer sinew contains rich collagen with a content of 82.12%. Thus, this article mainly studies the transdermal effect of collagen hydrolysates of deer sinew (DSCH) on mouse skin, ex vitro, and to explore skincare protection of percutaneous proteins. METHODS: Collagen hydrolysates of deer sinew were extracted by 0.2% HCl and a two-step enzymatic method of pepsin-trypsin. The content of 17 amino acids of DSCH was detected by precolumn derivatization RP-HPLC. Using Franz diffusion cell systems studied the transdermal effect of DSCH and then examined the percutaneous rate and molecular weight distribution of percutaneous proteins (PP). Further, we studied the bioactivity of PP in vitro, such as the total antioxidant capacity and collagen secretion in NIH/3T3 cells. RESULTS: About 8.0% DSCH could penetrate skin of mouse, the molecular weight of PP mainly distributed in 5 ~ 13 kDa, accounted for 91.55%. Compared with the antioxidant activity of DSCH, PP had obvious antioxidant activity of scavenging radical cation. Meanwhile, PP promoted cell proliferation and collagen I secretion in fibroblast cells; however, level of type III collagen has no change. CONCLUSION: Collagen hydrolysates of deer sinew may be used as cosmetic material to protect the skin from oxidative stress, to prevent premature skin aging.

Angiotensin-converting enzyme inhibiting ability of ethanol extracts, steviol glycosides and protein hydrolysates from stevia leaves.

Efficient treatment of hypertension is vital. The inhibition of angiotensin-converting enzyme activity has been one of the major strategies for treating hypertension. The ethanol extract of stevia leaves, steviol glycosides (with 95% purity; natural sweeteners widely used in the food industry) isolated from the ethanol extract and stevia leaf protein hydrolysates inhibited 26.60%, 59.56% and 74.38% of angiotensin-converting enzyme activities, respectively. Their effect was dose-dependent, which can be beneficial for avoiding hypertension or hypotension just by the proper control of the amount of their intake, and it was found to be superior to that of pharmaceutical drugs. A sensory test indicated that the application of the mixtures of steviol glycosides and stevia protein hydrolysates to decaffeinated coffee or tea as well as a formulated peanut protein drink was found to be well accepted, and an animal test showed that they had a significantly antihypertensive effect in spontaneously hypertensive rats. Steviol glycosides and stevia leaf protein hydrolysates can be good ingredients for making functional or healthy food products or beverages targeted for the prevention or treatment of hypertension.

Immunosuppressive effects of protein derivatives from Mucuna pruriens on a streptozotocin-induced type 1 diabetes murine model.

Type 1 diabetes is an autoimmune disease induced by abnormal insulin secretions from ß-cells in pancreas. The present study aimed to investigate the immunosuppressive effects from protein derivatives of Mucuna pruriens on a murine model of Type 1 diabetes. Hydrolyzate and five peptide fractions with different molecular weight were administered orally by 14 days, followed T1D murine model was built by intraperitoneal injection of streptozotocin over 5 days. The mice weight, blood glucose levels, anti-insulin, and anti-pancreatic islet ß-cells antibodies, pro-inflammatory cytokines as tumor necrosis factor alpha and interleukin-6 were determined in four times (0, 15, 30, and 45 day). Mice were sacrificed and pancreatic tissues samples were obtained and staining with hematoxylin and eosin to determine the degree of damage. The study demonstrated immunosuppressive activity in four of the six treatment groups: (a) T1D PPH, (b) T1D F 5-10 kDa, (c) T1D F 3-5 kDa, and (d) T1D F 1-3 kDa. PRACTICAL APPLICATIONS: Due to the high content of native protein in seeds of Mucuna pruriens, studies have reported potential in the elaboration of hydrolysates and peptides with biological activity. These protein derivatives could help in the treatment of immunological disorders that are observed in several chronic non-communicable disease and inflammatory diseases, such as T1D. Activated macrophages and lymphoplasmacytic infiltrate plays a crucial role in the initiation and maintenance of T1D; therefore, several studies has focused to reduce the effector functions of this cells for diminishing the clinical manifestations in inmmunocompromised patients. Thus, this study indicates the potential application of hydrolyzate and peptide fractions of M. pruriens in functional foods and dietary supplements could be developed for the treatment of inflammatory and chronic non-communicable diseases.

Purification and Characterization of Antioxidant Peptides Derived from Protein Hydrolysate of the Marine Bivalve Mollusk Tergillarca granosa.

In this report, protein hydrolysate (TGH) of blood cockle (Tegillarca granosa) was prepared using a two-enzyme system (Alcalase treatment for 1.5 h following Neutrase treatment for 1.5 h). Subsequently, six antioxidant peptides were isolated from TGH using ultrafiltration and chromatography methods, and their amino acid sequences were identified as EPLSD, WLDPDG, MDLFTE, WPPD, EPVV, and CYIE with molecular weights of 559.55, 701.69, 754.81, 513.50, 442.48, and 526.57 Da, respectively. In which, MDLFTE and WPPD exhibited strong scavenging activities on DPPH radical (EC50 values of 0.53 ± 0.02 and 0.36 ± 0.02 mg/mL, respectively), hydroxy radical (EC50 values of 0.47 ± 0.03 and 0.38 ± 0.04 mg/mL, respectively), superoxide anion radical (EC50 values of 0.75 ± 0.04 and 0.46 ± 0.05 mg/mL, respectively), and ABTS cation radical (EC50 values of 0.96 ± 0.08 and 0.54 ± 0.03 mg/mL, respectively). Moreover, MDLFTE and WPPD showed high inhibiting ability on lipid peroxidation. However, MDLFTE and WPPD were unstable and could not retain strong antioxidant activity at high temperatures (>80 °C for 0.5 h), basic pH conditions (pH > 9 for 2.5 h), or during simulated GI digestion. In addition, the effect of simulated gastrointestinal digestion on TGP4 was significantly weaker than that on MDLFTE. Therefore, MDLFTE and WPPD may be more suitable for serving as nutraceutical candidates in isolated forms than as food ingredient candidates in functional foods and products.

Characterization and Antioxidant and Angiotensin I-Converting Enzyme (ACE)-Inhibitory Activities of Gelatin Hydrolysates Prepared from Extrusion-Pretreated Milkfish (Chanos chanos) Scale.

Fish gelatin hydrolysates have been shown to possess various biological activities due to their unique Gly-Pro-Y and Gly-X-Hyp sequences. In the current study, fish gelatin was extracted from non-extruded milkfish scale (FSG1) or extrusion-pretreated milkfish scale (FSG2); extracted gelatins were hydrolyzed with different combinations of Flavourzyme and Alcalase to give four different hydrolysates, namely: FSGH1 (FSG1 hydrolyzed with Flavourzyme), FSGH2 (FSG1 hydrolyzed with Alcalase + Flavourzyme), FSGH3 (FSG2 hydrolyzed with Flavourzyme), and FSGH4 (FSG2 hydrolyzed with Alcalase + Flavourzyme). The extrusion-pretreatment process enhanced the extraction yield of gelatin from fish scale. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Fourier transform infrared (FTIR) analyses showed the extracts FSG1 and FSG2 possessed characteristics of gelatin. Moreover, the physicochemical characteristics of FSGH1⁻FSGH4 were examined by analyses of their degree of hydrolysis, amino acid composition, UV spectrum, FTIR spectrum, molecular weight, and RP-HPLC profile. Additional biological functional analyses showed that all of the studied gelatin hydrolysates FSGH1⁻FSGH4 possessed antioxidant activity dose-dependently as revealed by DPPH scavenging, ABTS scavenging, and reducing power analyses. In addition, FSGH2 and FSGH4 showed higher angiotensin-I-converting enzyme (ACE)-inhibitory activity as compared to FSGH1 and FSGH3. Taken together, FSGH2 and FSGH4 showed high antioxidant activity and potent anti-ACE activity. Due to the potential antioxidant and antihypertensive properties of FSGH2 and FSGH4, further research is needed to explore their possible use as natural supplementary raw materials in food and nutraceutical products.

Anti-hypertrophic and anti-apoptotic effects of short peptides of potato protein hydrolysate against hyperglycemic condition in cardiomyoblast cells.

Cardiomyocyte hypertrophy is a critical pathological phenomenon observed in diabetic cardiomyopathy. Various molecular events including the Calcineurin/nuclear factor of activated T-cell (NFAT) mediated signaling contributes to the pathogenesis of cardiac hypertrophy. While different new therapeutic interventions are investigated in order to overcome pathological hypertrophic effects, recent studies on peptide hydrolysates from common foods have gained interest. In this study the cytoprotective efficiency of two short peptides DIKTNKPVIF (DF) and a dipeptide IF from a potato protein hydrolysate were evaluated for their anti-hypertrophic effects against high glucose (HG) challenge. Murine cardio myoblast (H9c2) cells were challenges with 33 mM of glucose and after 1 h were treated with DF or IF for 24 h. The results showed enlargement in cell size, elevated ANP and BNP expression induced by HG however the abnormalities were efficiently attenuated by IF and DF. Further, HG increased the levels of calcineurin and NFATC3 which was markedly suppressed by DF and IF in H9c2 cells. The results further showed that DF and IF suppresses the activation of p38 in a dose dependent manner with no notable effects on JNK activation. DF and IF also attenuated the HG induced apoptotic effects in H9c2 cells by suppressing the apoptotic proteins and by enhancing the survival and anti-apoptotic proteins. Further, it should be noted that administration of both the fragments showed similar effects in all the analysis. Our results therefore showed that DF and IF of potato protein hydrolysate possess efficient protective effects against HG-induced cardiomyocyte damages by ameliorating the apoptotic and hypertrophic effects.

Oviductus ranae protein hydrolysate (ORPH) inhibits the growth, metastasis and glycolysis of HCC by targeting miR-491-5p/PKM2 axis.

BACKGROUND: Oviductus Ranae (OR) is a valuable Chinese crude drug and has been reported to have a range of biological activities. Protein hydrolysate extracted from OR (ORPH) was previously found to have immune regulatory effect and anti-glioma activity. This study was aimed to investigate the effects of ORPH on hepatocellular carcinoma (HCC) progression. METHODS: MTT, BrdU, colony formation and transwell assays were used to determine proliferation and mobility of HCC cells in vitro. Glucose consumption and lactate production assays were carried out to measure the glycolysis of HCC cells. The subcutaneous tumor model and lung metastasis model in nude mice were established to detect tumor growth and metastasis of HCC in vivo. The direct binding of miR-491-5p to 3'UTR of pyruvate kinase M2 (PKM2) was confirmed by luciferase reporter assay. RESULTS: In vitro experiments showed that ORPH significantly inhibited proliferation, migration, invasion, epithelial-to-mesenchymal transition (EMT) and glycolysis of HCC cells. Moreover, ORPH treatment prominently suppressed HCC growth and metastasis in mice. We demonstrated that ORPH effectively decreased the expression of PKM2 in HCC cells. Forced expression of PKM2 abrogated the inhibitory effects of ORPH on HCC cells. Mechanically, ORPH reduced PKM2 expression in a post-transcriptional manner by up-regulating miR-491-5p. miR-491-5p exhibited a similar tumor suppressive effects with ORPH in HCC cells. Moreover, ORPH exerted its inhibitory effects on HCC cells through regulating miR-491-5p/PKM2 axis. Lastly, decreased miR-491-5p level and increased PKM2 expression were correlated with unfavorable clinical features and poor prognosis of HCC patients. CONCLUSIONS: In all, this study reveals that ORPH inhibits the growth, metastasis and glycolysis of HCC cells by targeting miR-491-5p/PKM2 axis. ORPH may be a potential effective anti-tumor agent for HCC.

High-Pressure Homogenization Pretreatment before Enzymolysis of Soy Protein Isolate: the Effect of Pressure Level on Aggregation and Structural Conformations of the Protein.

The high-pressure homogenization (HPH) treatment of soybean protein isolate (SPI) before enzymatic hydrolysis using bromelain was investigated. Homogenization pressure and cycle effects were evaluated on the enzymatic degree of hydrolysis and the antioxidant activity of the hydrolysates generated. The antioxidant activity of SPI hydrolysates was analyzed by 1,1-dipheny-2-picrylhydrazyl (DPPH). The sizes and structures of the SPI-soluble aggregate after HPH treatment were analyzed using dynamic and static laser light scattering. The changes in the secondary structure, as measured by Fourier transform infrared spectroscopy (FTIR) and the macromorphology of SPI, were measured by scanning electron microscope (SEM). These results suggested that the HPH treatment (66.65%) could increase the antioxidant activities of the SPI hydrolysates compared with the control (54.18%). SPI hydrolysates treated at 20 MPa for four cycles obtained higher DPPH radical-scavenging activity than other samples. The control was predicted to be a hard sphere, and SPI treatment at 10 MPa was speculated to be Gaussian coil, polydisperse, and then the high-pressure treated SPI became a hollow sphere. Changes in the secondary structures showed protein aggregate formation and rearrangements. The image of SPI varied from a globular to a clump structure, as observed by the SEM. In conclusion, combining HPH treatment and enzymolysis could be an effective way to improve the antioxidant activity of the SPI.

High angiotensin-I converting enzyme (ACE) inhibitory activity of Alcalase-digested green soybean (Glycine max) hydrolysates.

As a protein-rich, underutilized crop, green soybean could be exploited to produce hydrolysates containing angiotensin-I converting enzyme (ACE) inhibitory peptides. Defatted green soybean was hydrolyzed using four different food-grade proteases (Alcalase, Papain, Flavourzyme and Bromelain) and their ACE inhibitory activities were evaluated. The Alcalase-generated green soybean hydrolysate showed the highest ACE inhibitory activity (IC50: 0.14 mg/mL at 6 h hydrolysis time) followed by Papain (IC50: 0.20 mg/mL at 5 h hydrolysis time), Bromelain (IC50: 0.36 mg/mL at 6 h hydrolysis time) and Flavourzyme (IC50: 1.14 mg/mL at 6 h hydrolysis time) hydrolysates. The Alcalase-generated hydrolysate was profiled based on its hydrophobicity and isoelectric point using reversed phase high performance liquid chromatography (RP-HPLC) and isoelectric point focusing (IEF) fractionators. The Alcalase-generated green soybean hydrolysate comprising of peptides EAQRLLF, PSLRSYLAE, PDRSIHGRQLAE, FITAFR and RGQVLS, revealed the highest ACE inhibitory activity of 94.19%, 99.31%, 92.92%, 101.51% and 90.40%, respectively, while their IC50 values were 878 µM, 532 µM, 1552 µM, 1342 µM and 993 µM, respectively. It can be concluded that Alcalase-digested green soybean hydrolysates could be exploited as a source of peptides to be incorporated into functional foods with antihypertensive activity.

Anticancer Activity of a Hexapeptide from Skate (Raja porosa) Cartilage Protein Hydrolysate in HeLa Cells.

In this study, the hexapeptide Phe-Ile-Met-Gly-Pro-Tyr (FIMGPY), which has a molecular weight of 726.9 Da, was separated from skate (Raja porosa) cartilage protein hydrolysate using ultrafiltration and chromatographic methods, and its anticancer activity was evaluated in HeLa cells. Methylthiazolyldiphenyl-tetrazolium bromide (MTT) assay indicated that FIMGPY exhibited high, dose-dependent anti-proliferation activities in HeLa cells with an IC50 of 4.81 mg/mL. Acridine orange/ethidium bromide (AO/EB) fluorescence staining and flow cytometry methods confirmed that FIMGPY could inhibit HeLa cell proliferation by inducing apoptosis. Western blot assay revealed that the Bax/Bcl-2 ratio and relative intensity of caspase-3 in HeLa cells treated with 7-mg/mL FIMGPY were 2.63 and 1.83, respectively, significantly higher than those of the blank control (p < 0.01). Thus, FIMGPY could induce apoptosis by upregulating the Bax/Bcl-2 ratio and caspase-3 activation. Using a DNA ladder method further confirmed that the anti-proliferation activity of FIMGPY was attributable to its role in inducing apoptosis. These results suggest that FIMGPY from skate cartilage protein hydrolysate may have applications as functional foods and nutraceuticals for the treatment and prevention of cancer.

Antioxidant, immunomodulatory and antiproliferative effects of gelatin hydrolysate from unicorn leatherjacket skin.

BACKGROUND: The in vitro cellular bioactivities including, antioxidant, immunomodulatory and antiproliferative effects of a gelatin hydrolysate (GH) prepared from unicorn leatherjacket skin, using partially purified glycyl endopeptidase, were investigated in order to optimize the use of fish skin waste products as functional food ingredients. RESULTS: GH under the tested concentrations (750-1500 µg mL(-1) ) protected against H2 O2 -induced DNA damage in U937 cells. GH also protected against the H2 O2 -induced reduction in cellular antioxidant enzyme activities, superoxide dismutase and catalase, in HepG2 cells. GH demonstrated immunomodulatory potential by reducing pro-inflammatory cytokine (interleukin-6 (IL-6) and IL-1ß) production and nitric oxide production in lipopolysaccharide-stimulated RAW 264.7 macrophage cells. Cell proliferation in human colon cancer (Caco-2) cells was significantly reduced in a dose-dependent manner following incubation with GH. CONCLUSION: These results indicate that GH has several bioactivities which support its potential as a promising functional food ingredient with various health benefits. © 2015 Society of Chemical Industry.

Production of the angiotensin I converting enzyme inhibitory peptides and isolation of four novel peptides from jellyfish (Rhopilema esculentum) protein hydrolysate.

BACKGROUND: Angiotensin I converting enzyme (ACE) plays an important role in regulating blood pressure in the human body. ACE inhibitory peptides derived from food proteins could exert antihypertensive effects without side effects. Jellyfish (Rhopilema esculentum) is an important fishery resource suitable for production of ACE inhibitory peptides. The objective of this study was to optimize the hydrolysis conditions for production of protein hydrolysate from R. esculentum (RPH) with ACE inhibitory activity, and to isolate and identify the ACE inhibitory peptides from RPH. RESULTS: Rhopilema esculentum protein was hydrolyzed with Compound proteinase AQ to produce protein hydrolysate with ACE inhibitory activity, and the hydrolysis conditions were optimized using response surface methodology. The optimum parameters for producing peptides with the highest ACE inhibitory activity were as follows: hydrolysis time 3.90 h, hydrolysis temperature 58 °C, enzyme:substrate ratio 2.8% and pH 7.60. Under these conditions, the ACE inhibitory rate reached 32.21%. In addition, four novel ACE inhibitory peptides were isolated, and their amino acids sequences were identified as Val-Gly-Pro-Tyr, Phe-Thr-Tyr-Val-Pro-Gly, Phe-Thr-Tyr-Val-Pro-Gly-Ala and Phe-Gln-Ala-Val-Trp-Ala-Gly, respectively. The IC50 value of the purified peptides for ACE inhibitory activity was 8.40, 23.42, 21.15 and 19.11 µmol L(-1) . CONCLUSION: These results indicate that the protein hydrolysate prepared from R. esculentum might be a commercial competitive source of ACE inhibitory ingredients to be used in functional foods. © 2015 Society of Chemical Industry.

Antioxidant and antiproliferative activities of protein hydrolysate from the rhizomes of Zingiberaceae plants.

Plant proteins have been investigated for their antioxidant activities, but there are still no reports detailing the antioxidant activity levels of plants in the Zingiberaceae family, which are popular food agents and used in folklore medicine. In this study, the crude rhizome protein extract and associated pepsin/pancreatin protein hydrolysate of 15 plants in the Zingiberaceae family were screened using the DPPH method for antioxidant activity. The protein hydrolysate of C. zedoaria possessed the highest antioxidant activity (IC50of 25.7±6.3µg/mL), which was close to that of the reference ascorbic acid (IC50of 22.3±1.8µg/mL). After enrichment by Q Sepharose ion exchange chromatography using a five step elution gradient of increasing NaCl concentration (0, 0.25, 0.5, 0.75 and 1M), the fraction eluting in the 0.5M NaCl (F50) showed the highest antioxidant activity (IC50 of 41.78±2.9µg/mL), and was found to have weak in vitro cytotoxicity against the HEP-G2 and SW620 cell lines (IC50 of 200.8±11.8 and 241.0±9.3µg/mL, respectively), but not the BT474, CHAGO and KATO-3 cell lines. F50 had an estimated molecular weight by MALDI-TOF mass spectrometry of 12,400-12,800 Da.

Improvement of glycemic control in streptozotocin-induced diabetic rats by Atlantic salmon skin gelatin hydrolysate as the dipeptidyl-peptidase IV inhibitor.

In our previous study, Atlantic salmon skin gelatin hydrolysed with flavourzyme possessed 42.5% dipeptidyl-peptidase (DPP)-IV inhibitory activity at a concentration of 5 mg mL(-1). The oral administration of the hydrolysate (FSGH) at a single dose of 300 mg per day in streptozotocin (STZ)-induced diabetic rats for 5 weeks was evaluated for its antidiabetic effect. During the 5-week experiment, body weight increased, and the food and water intake was reduced by FSGH in diabetic rats. The daily administration of FSGH for 5 weeks was effective for lowering the blood glucose levels of diabetic rats during an oral glucose tolerance test (OGTT). After the 5-week treatment, plasma DPP-IV activity was inhibited; the plasma activity of glucagon-like peptide-1 (GLP-1), insulin, and the insulin-to-glucagon ratio were increased by FSGH in diabetic rats. The results indicate that FSGH has the function of inhibiting GLP-1 degradation by DPP-IV, resulting in the enhancement of insulin secretion and improvement of glycemic control in STZ-induced diabetic rats.

Production of bioactive peptide hydrolysates from deer, sheep and pig plasma using plant and fungal protease preparations.

Plasma separated from deer, sheep and pig blood, obtained from abattoirs, was hydrolysed using protease preparations from plant (papain and bromelain) and fungal (FP400 and FPII) sources. Antioxidant and antimicrobial activities of the peptide hydrolysates obtained after 1, 2, 4 and 24h of hydrolysis, were investigated. The release of trichloroacetic acid-soluble peptides over the hydrolysis period was monitored using the o-phthaldialdehyde (OPA) assay, while the hydrolysis profiles were visualised using SDS-PAGE. The major plasma proteins in the animal plasmas were identified using MALDI-TOF-TOF MS. Hydrolysates of plasma generated with fungal proteases exhibited higher DPPH radical-scavenging, oxygen radical-scavenging capacity (ORAC) and ferric reducing antioxidant power (FRAP) than those generated with plant proteases for all three animal plasmas. No antimicrobial activity was detected in the hydrolysates. The results indicated that proteolytic hydrolysis of animal blood plasmas, using fungal protease preparations in particular, produces hydrolysates with high antioxidant properties.

Purification and characterisation of antibacterial peptide-containing compound derived from palm kernel cake.

Palm kernel cake (PKC), the most useful by-product resulted from palm kernel oil production. In this study, PKC-derived protein product was found suitable for use as an antimicrobial agent with potent antibacterial activity, particularly against Bacillus species, after enzymatic hydrolysis with alcalase. The hydrolysate was further purified by gel filtration chromatography. The purified fraction was found to have 14.63±0.70% (w/w) protein, a molecular mass of 2.4kDa and low hemolytic activity (<50% hemolysis of human erythrocytes at concentration of 1000µg/ml). The presence of lysine and the major component lauric acid derivative, as indicated by electrospray ionisation-mass spectrometry (ESI-MS) direct infusion and nuclear magnetic resonance (NMR) spectroscopy, may have contributed to the antibacterial effect of purified PKC fraction. This study suggests that the antibacterial PKC compound may be not a pure peptide but instead a peptide-containing compound high in lauric acid derivative.

Amino acid composition and antioxidant activities of hydrolysates and peptide fractions from porcine collagen.

The amino acid composition and antioxidant activities of different hydrolysates from porcine collagen were analyzed. The gelatin was hydrolyzed for antioxidative peptides with various proteases, namely papain, protease from bovine pancreas, protease from Streptomyces, and cocktail mixture of protease from bovine pancreas and protease from Streptomyces. The hydrolysates were assessed using methods of DPPH radical-scavenging ability, metal-chelating ability and lipid peroxidation inhibition activity. It was found that the collagen hydrolysates by different protease treatments had different amino acid compositions and antioxidant properties. However, the contents of Hyp and Pro were improved and the content of Gly was decreased in each collagen hydrolysate compared with collagen. The hydrolysate prepared with the cocktail mixture of proteases, which exhibited the highest antioxidant activity, was separated into 6 fractions by gel filtration chromatography. Fraction 2 was further separated by ion exchange chromatography. Fraction 2b with abundant basic amino acids and Fraction 2d which was slightly acidic fractions had higher radical-scavenging and metal-chelating activities, and both Fraction 2b and 2d contained more hydrophobic amino acids. The results confirmed that the antioxidative peptides were rich in Hyp, Pro and Gly, which accounted for half of amino acid composition. This article added further support to the preparation of natural antioxidative peptides from porcine skin collagen.

Isolation and identification of two novel umami and umami-enhancing peptides from peanut hydrolysate by consecutive chromatography and MALDI-TOF/TOF MS.

Peanut hydrolysate produced by crude protease extract from Aspergillus oryzae HN 3.042 was found to elicit intense umami and umami-enhancing effect. Taste profiles, amino acid and organic acid composition of peanut hydrolysate and its separation fractions by ultrafiltration were evaluated. The results revealed that peanut hydrolysate was mainly low molecular weight compounds. Fractions of 1-3 kDa and below 1 kDa prominently contributed to the umami taste and umami-enhancing effect of the peanut hydrolysate. The two fractions were further purified, using gel filtration chromatography and reverse-phase high-performance liquid chromatography (RP-HPLC), in combination with sensory evaluation, to obtain a umami peptide and umami-enhancing peptide. The active peptides were identified as Ser-Ser-Arg-Asn-Glu-Gln-Ser-Arg (SSRNEQSR, 963.9 Da) and Glu-Gly-Ser-Glu-Ala-Pro-Asp-Gly-Ser-Ser-Arg (EGSEAPDGSSR, 1091.1 Da), by MALDI-TOF/TOF MS, respectively.