Antioxidant, ACE-inhibitory and antimicrobial activities of Kluyveromyces marxianus protein hydrolysates and their peptide fractions

Background: There has been some evidence that proteins are potentially excellent source of antioxidants, antihypertensive and antimicrobial peptides and enzymatic hydrolysis is an effective method to release these peptides from protein molecules. The functional properties of protein hydrolysates depends on the protein substrate, the specificity of the enzymes, the conditions used during proteolysis, degree of hydrolysis, and the nature of peptides released including molecular weight, amino acid composition, and hydrophobicity. Context and purpose of this study: The biomass of Kluyveromyces marxianus was considered as a source of ACE inhibitory, antioxidant and antimicrobial peptides. Results: Autolysis and enzymatic hydrolysis were completed respectively, after 96 h and 5 h. Overall, trypsin (18.52% DH) and chymotrypsin (21.59% DH) treatments were successful in releasing antioxidant and ACE inhibitory peptides. Autolysate sample (39.51% DH) demonstrated a poor antioxidant and ACE inhibitory activity compared to trypsin and chymotrypsin hydrolysates. The chymotrypsin 3-5 kDa (301.6±22.81 μM TEAC/mg protein) and trypsin< 3 kDa (280.16±39.16) permeate peptide fractions showed the highest DPPH radical scavenging activity. The trypsin <3 kDa permeate peptide fraction showed the highest ABTS radical scavenging (1691.1±48.68 μMTE/mg protein) and ACE inhibitory (IC50=0.03±0.001 mg/ml) activities. The fraction (MW=5-10 kD) obtained after autolysis treatment showed antibacterial activity against St. aureus and Lis. monocytogenes in well diffusion screening. The minimum inhibitory concentration (MIC) value was 13.3 mg/ml against St. aureus and Lis. monocytogenes calculated by turbidimetric assay and it showed bactericidal activity against St. aureus at 21.3 mg/ml protein concentration. Conclusions: Taken together, the results of this study reveal that K. marxianus proteins contain specific peptides in their sequences which can be released by enzymatic hydrolysis and autolysis

Antioxidant activity and protective effects of Saccharomyces cerevisiae peptide fractions against H2O2-induced oxidative stress in Caco-2 cells

Oxidative stress is one of the most causes of some severe diseases and the spoilage of foods. Protein hydrolysates containing antioxidant peptides are a suitable candidate to replace synthetic antioxidant. In the present study, the in vitro and cellular antioxidant properties of Saccharomyces cerevisiae protein hydrolysate and the peptide fractions have been reported. The peptide protective role was evaluated in H2O2-stimulated Caco-2 cells to consider cell viability, cellular lipid and protein oxidation, and the level of cellular antioxidant enzymes such as Catalase (CAT) and Glutathione-S-transferase (GST). The peptide fractions showed a significant ferric reducing antioxidant power (67.10-93.52 mu m FeSO4/mg protein), and < 3 kDa peptide fraction with 59.5% inhibitory effect on the 7th day, exhibited the most inhibitory activity toward linoleic acid peroxidation. Ultrafiltered fractions ( < 3 kDa and 3-5 kDa) significantly (P <= 0.05) decreased the levels of malondialdehyde (MDA) and protein carbonyl and the production of CAT and GST enzymes as protective responses of cells under oxidative stress by H2O2. This study confirms the antioxidant activity of yeast protein hydrolysate and peptide fractions and their potential to reduce cellular oxidative stress and thus validates their potential use as a valuable ingredient of functional foods

The stability of antioxidant and ACE-inhibitory peptides as influenced by peptide sequences

As the structural characteristics of peptides affect their functional properties, they are an important factor for peptide stability. The stability characteristic was investigated in two groups of synthetic peptides, analogues of VLSTSFPPK (VL-9). The latter was previously purified from Kluyveromyces marxianus protein hydrolysate. In the first group, the replacement impact of Pro in antepenultimate position with Tyr, Cys and His on antioxidant stability against heat, NaCl, and pH and in the second group, the replacement effect of Lys in C-terminal with Trp, Tyr, and Phe on the stability of antihypertensive activity under gastrointestinal digestion were studied. Pro containing peptide (VL-9) showed the highest antioxidant stability against heat and salt. Despite the positive effect of Cys in antioxidant activity of peptides (VCK-9), it decreased the heat and salt stability. Tyr increased the ABTS cation radical scavenging activity and resulting peptide had the same thermal stability as the primary peptide and higher sensitivity to salt. Despite not significant effect of His on the antioxidant activity, it caused a slight instability against heat and salt. The antioxidant peptides studied showed the highest stability at neutral pH. The higher hydrophilicity of Lys in the peptide sequence caused higher ACE-inhibitory stability in simulated GI digestion

In vitro and in silico studies of novel synthetic ACE-inhibitory peptides derived from Saccharomyces cerevisiae protein hydrolysate

The structure-function relation of YR-10 (YGKPVAVPAR) was investigated by synthesizing four structural analogs of that including YHR-10 (YGKHVAVHAR), GA-8 (GKPVAVPA), GHA-8 (GKHVAVHA), and PAR-3 (PAR). GA-8 (GKPVAVPA) was synthesized on the basis of simulated enzymatic gastrointestinal digestion performed by bioinformatics tools (expasy-peptide cutter). This study explains the molecular mechanisms for the interaction of synthetic peptides with ACE. The IC50 values of each were 139.554 +/- 2.3, 61.91 +/- 1.2, 463.230 +/- 3.56, 135.135 +/- 2.1, 514.024 +/- 5.86 mu M, respectively. Results indicated that Pro replacement with His in YR-10 and GA-8 increased ACE inhibitory activity respectively, by 55.63% and 70.82%. Removal of Tyr and Arg from respectively N and C terminal positions of YR-10, following in silico simulated gastrointestinal digestion caused the 3.31 fold decrease in ACE inhibitory activity. YHR-10 showed the best docking poses, and GHA-8 exhibited interaction with Zn2+. Lineweaver-Burk plots of most active peptides suggest that they act as noncompetitive inhibitors against ACE

Risk assessment of isolated lactobacill from traditional Iranian dairy products

The application of probiotic starter cultures in fermented products is expanding in different communities. The genetic variation makes the effects of these bacteria different and unpredictable in different human societies. Therefore, the safety control and evaluation of their non-pathogenicity is of great importance and monitoring centers are required to closely monitor the safety of the bacteria used in food products. In this study, two strains of Lactobacillus isolated from dairy products of Ardabil (Heyran mountain road villages) and Khuzestan province (Behbahan city) in Iran were identified based on the biochemical and molecular properties through sequence analysis of 16S rRNA gene. Then, their safety was examined based on the international guidelines, especially the European :union: standard. The two identified strains included Lactobacillus fermentum (PTCC 1929) and Lactobacillus helveticus (PTCC 1930). The results showed the lack of gelatinase enzyme, inability of blood hemolysis, inability of amino acids decarboxylation and the lack of genes responsible for the invasive characteristics of pathogenic microorganisms including gelE, efaAfm , efaAfs , agg, ace, cylM, cylA, cylB. In addition, the results showed the sensitivity of both isolates to Penicillin, Ampicillin, Rifampicin and Tetracycline, and their resistance to Kanamycin and Ciprofloxacin. Lactobacillus fermentum was resistant to vancomycin, whereas Lactobacillus helveticus was susceptible to it. Since cases of antibiotic resistance are inherent according to scientific reports, the obtained results confirmed the potential application of these two isolated strains as starter in the fermented dairy products. It also confirmed the necessity of using safety assessment procedures for probiotic bacteria

Production of antioxidant and ACE-inhibitory peptides from Kluyveromyces marxianus protein hydrolysates: Purification and molecular docking

Kluyveromyces marxianus protein hydrolysates were prepared by two different sonicated-enzymatic (trypsin and chymotrypsin) hydrolysis treatments to obtain antioxidant and ACE-inhibitory peptides. Trypsin and chymotrypsin hydrolysates obtained by 5 h, exhibited the highest antioxidant and ACE-inhibitory activities. After fractionation using ultrafiltration and reverse phase high performance liquid chromatography (RP-HPLC) techniques, two new peptides were identified. One fragment (LL-9, MW = 1180 Da) with the amino acid sequence of Leu-Pro-Glu-Ser-Val-His-Leu-Asp-Lys showed significant ACE inhibitory activity (IC50 = 22.88 μM) while another peptide fragment (VL-9, MW = 1118 Da) with the amino acid sequence of Val-Leu-Ser-Thr-Ser-Phe-Pro-Pro-Lys showed the highest antioxidant and ACE inhibitory properties (IC50 = 15.20 μM, 5568 μM TE/mg protein). The molecular docking studies revealed that the ACE inhibitory activities of VL-9 is due to interaction with the S2 (His513, His353, Glu281) and S′1 (Glu162) pockets of ACE and LL-9 can fit perfectly into the S1 (Thr345) and S2 (Tyr520, Lys511, Gln281) pockets of ACE. Keywords: K. marxianus, Bioactive peptides, Antioxidant, ACE inhibitory, Protein hydrolysat

Improved anti-inflammatory properties of xanthan gum hydrogel physically and chemically modified with yeast derived peptide

Abstract Bioactive peptides from natural resources with associated beneficial biological properties such as skin wound healing have drawn much attention. Polysaccharides with their biocompatibility, biodegradability, and ease of modification are suitable carriers for peptides delivery to the wound. In this study, a polysaccharide-peptide system was designed for potential wound healing applications. Xanthan hydrogels were modified with the yeast-derived peptide VW-9 with known biological properties via chemical conjugation using carbodiimide chemistry (XG-g-VW-9) or physically incorporation (XG-p-VW-9). Grafting VW-9 to the hydrogels increased the hydrogels’ swelling degree and the release of the peptide from the hydrogels followed the Higuchi model indicating the peptide diffusion from the hydrogel matrix without hydrogel matrix dissolution. Both hydrogels were cytocompatible toward the tested fibroblast and macrophage cells. XG-p-VW-9 and XG-g-VW-9 reduce the level of tumor necrosis factor-alpha and interleukin-6 in cells activated with lipopolysaccharide more efficiently than free VW-9. Thus, VW-9-modified xanthan hydrogels may have the potential to be considered for skin wound healing.info:eu-repo/semantics/publishe

Effect of pectin on anti-diabetic and anti-oxidant properties of fermented milk by lactic acid bacteria isolated from traditional Iranian dairy products

Volume 19, Issue 123 (2022) FSCT 2022, 19(123): 55-67 | Back to browse issues page ‎ 10.52547/fsct.19.123.55 ‎ 20.1001.1.20088787.1401.19.123.20.5 XML Persian Abstract Print Download citation: BibTeX | RIS | EndNote | Medlars | ProCite | Reference Manager | RefWorks Send citation to: Mendeley Zotero RefWorks shirkhan F, Mirdamadi S, Mahta Mirzaei M, Akbari-Adergani B, Nasoohi N. Effect of Pectin on Anti-diabetic and Anti-oxidant Properties of Fermented Milk by Lactic Acid Bacteria Isolated from Traditional Iranian Dairy Products. FSCT. 2022; 19 (123) :55-67 URL: http://fsct.modares.ac.ir/article-7-57521-en.html Effect of Pectin on Anti-diabetic and Anti-oxidant Properties of Fermented Milk by Lactic Acid Bacteria Isolated from Traditional Iranian Dairy Products Faezeh Shirkhan1, Saeed Mirdamadi2, Mahta Mahta Mirzaei3, Behrouz Akbari-Adergani4, Nikoo Nasoohi5 1- Department of Food Science and Technology, Faculty of Pharmacy, Tehran Medical Sience, Islamic Azad Univercity,Tehran, Iran 2- Professor, Department of Biotechnology, Iranian Research Organization for Science & Technology (IROST), Tehran, Iran , [email protected] 3- Assistant Professor, Department of Food Science and Technology, Shahr-e-Qods Branch, Islamic Azad University, Tehran, Iran 4- Professor of Food and Drug Laboratory Research Center, Food and Drug administration, Ministry of Health and Medical Education 5- Assistant Professor, Department of Biochemistry and Biophysics, Faculty of Advanced Science and Technology, Tehran Medical Sciences, Islamic Azad University, Tehran, Iran Abstract: (579 Views) Abstract Nowadays, Polysaccharides are used to improve the nutritional and physicochemical properties of dairy products. The identification of natural compounds such as polysaccharides with antidiabetic and antioxidant properties has become important due to the relationship between diabetes and oxidative stress. Therefore, the present study aimed to evaluate the influence of pectin on the antidiabetic and antioxidant activity of milk fermented by lactic acid bacteria (LAB) isolated from traditional Iranian dairy products. Pectin (1%) was added to the samples following milk fermentation by Lactobacillus helveticus and Lactobacillus para-casei strains, and antidiabetic activity was assessed by considering the inhibitory effects on α-amylase and α-glucosidase. The antioxidant activity was determined by evaluating inhibition of 2,2-Diphenyl-1-picrylhydrazyl (DPPH), 2,2-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) and hydroxyl radicals. Samples included pectin solution (0.5-3.5 mg/ml and 0.5-10 mg/ml for evaluation of anti-diabetic and antioxidant activity, respectively), whey of fermented and non-fermented milk with (1%) and without pectin. The results indicated the role of pectin on inhibition of α-glucosidase enzyme activity (IC50=2.38 mg/ml), as well as scavenging the DPPH (44.57%), ABTS (28.7%), and Hydroxyl (38.85%) radicals (P<0.05) a concentration of 10 mg/ml. Pectin added to the whey of non-fermented milk sample boosted antioxidant properties and the maximum rate of free radical scavenging activity (35%) was obtained for DPPH radicals. Furthermore, adding pectin to the whey of milk fermented with Lactobacillus helveticus strain improved the activity of the product on inhibition of α-glucosidase enzyme (29%), scavenging of DPPH (41.26 %), ABTS (2.5%), and hydroxyl radicals (7.64%) (P<0.05). The results indicated the potential of pectin to be used in the formulation of beneficial food products due to its ability to improve the antioxidant and anti-diabetic properties of fermented milk products