Highest ACE-inhibitory Activity Research Articles

Angiotensin-converting enzyme inhibitory peptides from Lactobacillus delbrueckii QS306 fermented milk

Angiotensin-converting enzyme inhibitory peptides were isolated and identified from milk fermented using Lactobacillus delbrueckii QS306. The peptide with the highest angiotensin-converting enzyme inhibitory activity (C5) was purified using ultrafiltration with 10 and 3 kDa molecular mass cut-off membranes, Sephadex G-15 (Sigma-Aldrich, St. Louis, MO) gel filtration chromatography, reversed-phase HPLC, and Orbitrap Elite (Thermo Fisher Scientific Inc., Waltham, MA) liquid chromatography-tandem mass spectrometry. We obtained peptide LPYPY by microbial fermentation, which was derived from κ-casein f (AA 77-81). We synthesized LPYPY using an Fmoc solid-phase synthesis method and explored the secondary structure of the pentapeptide. The half maximal inhibitory concentration for the angiotensin-converting enzyme inhibitory activity of LPYPY was 12.87 μg/mL. The results provide additional information for ongoing research and the development of functional foods having antihypertensive effects.

A novel angiotensin-I converting enzyme inhibitory peptide derived from the glutelin of vinegar soaked black soybean and its antihypertensive effect in spontaneously hypertensive rats.

Vinegar soaked black soybean is a traditional Chinese food widely used for the treatment of hypertension. While its pharmacodynamic substance was not fully unveiled. It contained abundant glutelin, thus the purpose of this study was to obtain potent antihypertensive peptides from vinegar soaked black soybean. Black soybean was soaked with vinegar and then glutelin was first catalyzed by alcalase. Ultrafiltration, ion exchange chromatography and reversed-phase high performance liquid chromatography were sequentially applied to separate and purify the angiotensin-I converting enzyme (ACE) inhibitory peptides from glutelin hydrolysates. As a result, the fraction L1-4 with the highest ACE inhibitory activity (83.41%) at the final concentration of 0.01 mg/ml was obtained and five peptides were then identified. These peptides were further optimized by virtual screening combining with in silico proteolysis. Finally, a novel tetrapeptide Phe-Gly-Ser-Phe (FGSF) was obtained. FGSF exhibited high in vitro ACE inhibitory activity (IC50 = 117.11 μM) and in vivo hypotensive effect which maximally reduced systolic blood pressure of 21.95 mmHg at 20 mg/kg body weight in spontaneously hypertensive rats. Our study demonstrated that FGSF derived from vinegar soaked black soybean might be used as a promising ingredient for pharmaceuticals against hypertension and its related diseases.

Nutritional composition and angiotensin converting enzyme inhibitory activity of blue lupin (Lupinus angustifolius)

The nutritional, protein and amino acid compositions of blue lupin (Lupinus angustifolius) flour were studied. The angiotensin converting enzyme (ACE) inhibitory activity of lupin protein isolate (LPI) hydrolysates prepared using Alcalase and Flavourzyme, and the Osborne protein fractions hydrolysates prepared using Alcalase were determined. Lupin flour was high in protein (43 g/100 g) and dietary fiber (34 g/100 g) but low in carbohydrate (4.8 g/100 g) and ash (3.4 g/100 g). Results from a sequential Osborne extraction procedure showed that lupin protein was comprised of 56% globulin, 26% albumin and 19% glutelin, while prolamin was only found in trace amounts. Lupin protein was high in Lys but limiting in Met. SDS-PAGE analysis suggested that protein hydrolysis catalyzed using Alcalase was more effective than Flavourzyme as shown by the presence of lower molecular weight peptides in the former. LPI hydrolysates prepared using Alcalase showed high ACE inhibitory activities with IC50 values ranging from 0.10 to 0.21 mg/ml. The results suggested that the globulin fraction was the main contributor towards the ACE inhibitory activity observed in lupin protein.

Controlled enzymatic hydrolysis of pollen protein as promising tool for production of potential bioactive peptides.

In the present study, response surface method was used to optimize hydrolysis condition to generate potential bioactive peptides from pollen protein using pepsin (pepsin hydrolysated pollen-PHP) and trypsin (trypsin hydrolysated pollen-THP). Then PHP and THP prepared under optimized conditions were analyzed by size-exclusion chromatography. The fractions possessing the maximum ACE-inhibitory, DPPH radical scavenging, and ferric-reducing power were further purified by RP-HPLC. A heterogeneous composition of hydrophobic and hydrophilic peptides in both fractions was obtained. Finally, peptide sequences in active fractions of PHP and THP were identified by mass spectrometry in tandem. All the identified peptides had herbal protein origins. These were 6-21 amino acids in length, and Glycine and Alanine were two main hydrophobic amino acids present in their sequences. The results proved that using controlled enzymatic hydrolysis of pollen protein is possible to generate bioactive peptides with high ACE-inhibitory and antioxidant activity in final product. PRACTICAL APPLICATIONS: Pollen is well-known as an interesting protein source. Compared to other types of hydrolysis, enzymatic hydrolysis of vegetable proteins has few or no undesirable side reactions or products. In this study, controlled enzymatic hydrolysis of pollen protein was applied as a suitable method to produce bioactive peptide. The results proved that using controlled enzymatic hydrolysis of pollen protein is possible to generate bioactive peptides with high ACE-inhibitory and antioxidant activity in final product. This product can be used as functional and health promoting ingredient in different food formulations.

Isolation and characterisation of angiotensin converting enzyme (ACE) inhibitory peptides in fermented milk of malabari goat

A study was conducted to isolate and characterise the angiotensin converting enzyme (ACE) inhibitory peptides from fermented milk of Malabari goat. Goat milk was fermented with seven different lactic acid bacterial cultures including Lactobacillus acidophilus (MTCC 10307), L. plantarum (NCDC 379), L. casei (NCDC 017), L. bulgaricus (NCDC 253), L. paracasei sub sp . paracasei (NCDC 022), L. rhamnosus (MTCC 8712) and L. helveticus (NCDC 192). These cultures were inoculated at 3 and 4% levels for the preparation of fermented milk. The pH, titratable acidity, lactic acid bacterial count, proteolytic activity and ACE inhibitory activity of the fermented milk ranged from 4.07 to 5.69, 0.36 to 1.24% lactic acid, 9.79 to 10.25 log cfu/ml, 0.32 to 0.69 and 67.56 to 97.55%, respectively. The highest ACE inhibitory activity was observed in milk fermented with L. plantarum (NCDC 379). Fermented milk with high ACE inhibitory activity were subjected to reverse phase high performance liquid chromatography to isolate the ACE inhibitory peptides. Characterisation of the peptides was done by Tris-tricine SDS-PAGE. The molecular weight of ACE inhibitory peptides was 1.4 kDa. It can be concluded that Malabari goat milk fermented with lactic acid bacteria is a rich source of ACE inhibitory peptides.

Identification of angiotensin I-converting enzyme inhibitory peptides from enzymatic hydrolysates of pork loin

ABSTRACT This study aimed to identify angiotensin I-converting enzyme (ACE) inhibitory peptides in enzymatic hydrolysates from pork loin. Pork hydrolysates were produced by injecting different enzymes to the loins as follows: un-injected pork (fresh pork), injected with water (no enzyme control), 100 ppm protease type XIII (E1), 80 ppm thermolysin (E2), and the combination of 100 ppm protease type XIII and 80 ppm thermolysin (E3). The highest degree of hydrolysis (96.7%) and ACE inhibitory activity (90.1%) were observed in the E2-treated hydrolysate. Next, the E2-treated hydrolysate was fractionated and purified by using two different chromatographic methods, and the fractions with the highest ACE inhibitory activity were selected at each step. Finally, two peptides (Leu-Val-Gly-Arg-Pro-Arg-His-Gly-Gln and Val-Phe-Pro-Ser) were identified in the E2-treated hydrolysate using UPLC-QTOF-MS/MS. The smaller peptide, Val-Phe-Pro-Ser, showed a lower IC50 value for ACE inhibitory activity than the nona-peptide and captopril, a commercial ACE inhibitor. The results of this study suggest that the isolated nona-peptide, Leu-Val-Gly-Arg-Pro-Arg-His-Gly-Gln, possessed strong ACE inhibitory activity. Therefore, overnight incubation of fresh pork in a refrigerator after thermolysin injection may make the pork more beneficial for human consumption.

Synergistic effect of fruit\u2013seed mixed juice on inhibition of angiotensin I-converting enzyme and activation of NO production in EA.hy926 cells

Commonly consumed fruit juices possess low inhibitory activity of angiotensin I-converting enzyme (ACE), which plays central role in elevation of blood pressure. The ACE inhibitory activity of fruit–seed mixed juice may be improved via synergistic interactions. In this study, the investigated synergistic, additive, and antagonistic effects of fruit–seed combination on ACE inhibition were investigated. Thirteen fruits and 15 seeds including legumes, nuts, and cereals were combined in pairs; pear-hemp seed-pumpkin seed juice (3-mixed juice) displayed the highest ACE inhibition resulting from synergistic interactions. Additionally, nitric oxide production in human endothelial cells was promoted by 3-mixed juice. Three-mixed juice showed antioxidant activities such as DNA protective, DPPH radical scavenging, and reducing effects. These results suggested that combinations of different food categories are beneficial for improving biological functions such as vascular health. Three-mixed juice, which shows high ACE inhibitory activity, may be useful as an anti-hypertensive agent and for treating hypertension.

Physicochemical, conformational properties and ACE-inhibitory activity of peanut protein marinated by aged vinegar

The purpose of this paper was to study the effect of vinegar marinating, a Chinese traditional method, on the physicochemical, conformational properties, and angiotensin converting enzyme (ACE) inhibitory activities of peanut protein, so as to provide understandings to produce functional foods. Results of surface hydrophobicity and of fluorescence emission spectra demonstrated that the hydrophobicity of the soaked peanut protein was weakened or decreased. Fourier transformation infrared (FTIR) data indicated that marinating led to a more flexible structure of peanut protein droplet, because the secondary structure β-sheet was decreased and α-helix was increased in the marinated peanut. Compared to the native peanut, the marinated peanut had higher ACE-inhibitory activities and was more susceptible to enzyme during digestion process for the low content of β-sheet. Moreover, because more small peptides (∼5.5 kDa) were produced, ACE-inhibitory capacities of the marinated were enhanced more in vitro mimic gastrointestinal digestion than was done the native. This study shows that vinegar marinating enhances the ACE inhibition ability of peanut protein by altering its stereo structure, and this enhanced ability is stable after digestion and even increased, suggesting that vinegar marination is a valuable method of producing bioactive peptides.

Screening of Angiotensin-I Converting Enzyme Inhibitory Peptides Derived from Caulerpa lentillifera.

Peptides with angiotensin-I converting enzyme (ACE) inhibitory activity have received considerable interest due to their potential as antihypertensive agents and consumer concern over the safety of synthetic drugs. The objective of this study was to isolate ACE inhibitory (ACEI) peptides from Caulerpa lentillifera (known commonly as sea grape) protein hydrolysate. In this study, short-chain peptides were obtained after hydrolysis by various enzymes and subsequently by ultrafiltration. Thermolysin hydrolysate showed the highest ACEI activity. Bioassay-guided fractionation was performed using reversed-phase high performance liquid chromatography (RP-HPLC) to uncover the fraction 9 with the highest ACE inhibitory activity from thermolysin hydrolysate. Peptides in this fraction were further identified using liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis coupled with de novo sequencing, which gave two oligopeptides, FDGIP (FP-5) and AIDPVRA (AA-7). The identities and activities of these two peptides were further confirmed using synthetic peptides. Their IC50 values were determined as 58.89 ± 0.68 µM and 65.76 ± 0.92 µM, respectively. Moreover, the inhibition kinetics revealed that both FP-5 and AA-7 are competitive inhibitors. These activities were further explained using molecular docking simulation. The present study is the first report about ACEI peptides derived from Caulerpa lentillifera and it shows the potential for preventing hypertension and for functional food development.

Optimization of Hydrolysis Conditions for the Isolation of Angiotensin-I Converting Enzyme (ACE) Inhibitory Peptides from Rhopilema hispidum

To obtain the maximum angiotensin-I converting enzyme (ACE) inhibitory activity, the protein hydrolysis conditions of the jellyfish Rhopilema hispidum were optimized using response surface methodology (RSM). Trypsin was selected to produce R. hispidum protein hydrolysates (RPH) with ACE inhibitory activity. The optimal parameters for producing protein hydrolysates with the highest ACE inhibitory activity were as follows: hydrolysis time 5 h, hydrolysis temperature 50°C, and the enzyme-to-substrate ratio 6%. Under these conditions, the ACE inhibitory rate of RPH could reach 64.28% ± 5.72%. In addition, RPH contained high levels of Gly, Glu, Pro, Ala, Asp and Arg, with a molecular weight distribution range of 0.32–6.84 kDa. The following three novel ACE inhibitory peptides were isolated and identified: Ile-Gly-Glu-Thr-Gly-Pro, Gly-Ala-Thr-Gly-Pro-Ala-Gly-Tyr-Val and Gly-Ala-Phe-Gly-Pro-Gly-Gly-Leu-Val-Gly-Arg-Pro. The IC50 values of the ACE inhibitory activity of these three purified peptides were 19.07, 27.42 and 31.26 μmol L−1, respectively. These results suggested that proteins and peptides isolated from R. hispidum could be utilized as antihypertensive functional food sources.

Peptidomic Analysis of ACE Inhibitory Peptides Extracted from Fermented Goat Milk

Angiotensin converting enzyme (ACE) is considered as main causative agent in growing hypertension and other cardiovascular disorders. Inhibition of ACE by producing and purifying bioactive peptides of fermented goat milk is aimed in this study. Protein extracted from goat milk was hydrolyzed with proteolytic enzymes of LH (Lactobacillus helveticus-cicc22171). ACE inhibitory peptides were purified from fermented samples of goat milk protein by optimizing incubation time to 8 h (S-8), 16 h (S-16), 24 h (S-24) and 36 h (S-36), via ultrafiltration. S-8 was used as control to compare the ACE inhibition trend. Molecular weight cut-off; 10000 Da (PM-10) and Ultracel 3K membrane was used to perform ultrafiltration. Sample with 24 h incubation time was considered as best hydrolyzed as compared to others, by applying Nin-Hydrin reaction and SDS-PAGE analysis. ACE inhibitory assay validated the authenticity of S-24 in inhibiting ACE, in vitro. Furthermore, Q executive hybrid quadrupole-orbitrap mass spectrometry was used to determine molecular structure and amino acid sequence of ACE inhibitory peptides. Three peptides, VLPVPQKAVPQ, VLPVPQKVVPQ and TQTPVVVPPFLQPEIMGVPKVKE containing functional amino acid structure, has been identified with highest ACE inhibitory activity on the basis of intensity, size and higher concentration of hydrophobic amino acids as shown in figure as graphical abstract. Fermented goat milk containing these novel bioactive peptides, can be used as nutraceuticals to inhibit ACE and control hypertension in future.

Purification and identification of dipeptidyl peptidase IV and angiotensin-converting enzyme inhibitory peptides from silver carp (Hypophthalmichthys molitrix) muscle hydrolysate

Diabetes and hypertension are increasing threats to human health, which could be improved by inhibiting dipeptidyl peptidase IV (DPP-IV) and angiotensin-converting enzyme (ACE), respectively. Herein, we used five different enzymes to hydrolyze silver carp (Hypophthalmichthys molitrix) muscle protein. Among all treatments, the Neutrase-generated hydrolysate that was purified by a three-step isolation and then was identified using liquid chromatography–tandem mass spectrometry resulted in the most potent DPP-IV inhibitory activity and relatively high ACE inhibitory activity. The identified peptide Ala-Ala-Leu-Glu-Gln-Thr-Glu-Arg was the most effective at inhibiting DPP-IV with a half-maximal inhibitory concentration (IC50) value of 647.02 ± 4.30 µM. Leu-Leu-Asp-Leu-Gly-Val-Pro showed the highest ACE inhibitory activity with an IC50 value of 329.33 ± 15.53 µM. Lys-Ala-Val-Gly-Glu-Pro-Pro-Leu-Phe exhibited the dual inhibition against both DPP-IV and ACE with IC50 values of 1,317.39 ± 20.93 µM and 726.01 ± 8.69 µM, respectively. Interestingly, it seemed that the majority of peptides which were responsible for inhibiting DPP-IV were different from the ones which caused the inhibition of ACE.

Amino acid composition and antioxidant properties of Moringa oleifera seed protein isolate and enzymatic hydrolysates

The aim of this work was to compare the antioxidant and angiotensin converting enzyme (ACE) inhibitory properties of Moringa oleifera seed protein isolate (ISO) and its enzymatic protein hydrolysates. ISO was subjected to enzymatic (alcalase, pepsin and trypsin) hydrolysis to obtain alcalase isolate, pepsin isolate and trypsin isolate hydrolysates (AIH, PIH, TIH). Amino acid composition was similar for the samples except that TIH had lower Sulphur-containing amino acids while PIH was lower in tryptophan. All the samples were tested for antioxidant properties through free radical scavenging abilities such as 2,2 diphenyl-1-picrylhydrazyl (DPPH) and hydroxyl radical scavenging assays as well as ferric reducing antioxidant power (FRAP) and metal ion chelation assays. The maximum percentage inhibition obtained for the samples from the different assays are: DPPH, 36% (PIH); FRAP, 0.04% (PIH); hydroxyl radical scavenging activity, 42.98% (ISO); and inhibition of metal ion chelation, 29.46% (AIH). AIH (79.3%) had the highest ACE-inhibitory activity followed by TIH (75.1%) while PIH (43.0%) had the least. Generally, the hydrolysis process produced hydrolysates with improved antioxidant and ACE-inhibitory properties when compared to the isolate. We conclude that enzymatic hydrolysis with alcalase, pepsin and trypsin may be used to produce M. oleifera seed protein hydrolysates with potential to be used as ingredients for the formulation of functional foods and nutraceuticals.

Protein components of water extracts from fruiting bodies of the reishi mushroom Ganoderma lucidum contribute to the production of functional molecules

Mushrooms have been widely considered as health foods as their extracts have anti-hypertensive and anti-tumor activities. After a thorough literature survey, we hypothesized that enzymes in mushroom extracts play an important role in synthesizing functional molecules. Therefore, in this study, proteins extracted from reishi mushroom (Ganoderma lucidum), which is used in oriental medicine, were identified by the proteomic approach, and appropriate extraction methods for improving angiotensin-converting enzyme (ACE) inhibitory activities were investigated. Various glycoside hydrolases (GHs), such as β-N-acetylhexosaminidase (GH family 20), α-1,2-mannosidase (GH family 47), endo-β-1,3-glucanase (GH family 128), and β-1,3-glucanase (GH152), that degrade glycans in the fruiting body were identified. The residual glucanase activities generated β-oligosaccharides. Additionally, the glutamic acid protease of the peptidase G1 family was determined as the major protein in the extract, and the residual peptidase activity of the extracts was found to improve ACE inhibitory activities. Finally, it was observed that extraction at 50 °C is suitable for yielding functional molecules with high ACE inhibitory activities. Water extraction is generally believed to extract only functional macromolecules that exist in mushroom fruiting bodies. This study proposed a new concept that describes how functional molecules are produced by enzymes, including proteases and GHs, during extraction. © 2018 Society of Chemical Industry.

Effects of sweeping frequency ultrasound pretreatment on the hydrolysis of zein: angiotensin-converting enzyme inhibitory activity and thermodynamics analysis

In this study, we evaluated the effects of sweeping frequency ultrasound (SFU) pretreatment on the angiotensin-converting enzyme (ACE) inhibitory activity of zein hydrolysates and enzymatic hydrolysis thermodynamics. The solubility, surface hydrophobicity (Ho ), degree of hydrolysis (DH) of zein and ACE inhibitory activity of hydrolysates were determined. After SFU pretreatment, the solubility and Ho of zein were significantly increased. During the hydrolysis process, ultrasonic pretreatment significantly increased the DH of zein and the ACE-inhibitory activity of zein hydrolysates by 19.37 and 133.76%, respectively. First-order kinetics could be used to explain both traditional and ultrasonic-assisted hydrolysis. In contrast to traditional hydrolysis, the reaction rate constants of SFU-assisted hydrolysis were largely increased by 82.76, 17.81, 23.96, and 21.26% at hydrolysis temperatures of 293, 303, 313, and 323K, respectively. For the thermodynamic parameters, SFU pretreatment decreased activation energy, enthalpy of activation, entropy of activation, and free energy of activation by 19.52, 20.63, 6.16, and 7.02% respectively. In conclusion, SFU pretreatment markedly enhanced the hydrolysis of zein, and this method could be applied to the protein proteolysis industry to produce zein peptides with high ACE inhibitory activity.

Bioactive properties of fermented donkey milk, before and after in vitro simulated gastrointestinal digestion

Indigenous strains of lactic acid bacteria previously isolated from raw donkey milk samples were used to ferment donkey milk. Each sample was subjected to an in vitro simulated gastrointestinal digestion (SGID) and analysis of the digesta by HPLC-LTQ-Orbitrap XL was performed in order to obtain a comprehensive peptide profile of fermented donkey milk. Functional properties such as ACE-inhibitory, antimicrobial and antioxidant activities of the resulting fermented donkey milks, as well as characterization of the bioactive peptides produced by an in vitro SGID, were assayed. All bioactivities were found to be high in fermented milk and a further significant increase was observed after SGID. The Enterococcus faecium DM33 fermented milk exhibited the strongest antioxidant and the highest antimicrobial activities. The highest ACE-inhibitory activity was observed in milk fermented with Lactobacillus casei DM214. These findings will contribute to the development of a new functional dairy drink with anti-hypertensive, antimicrobial and/or antioxidant activities.

Bioactive properties of Kilka (Clupeonella cultriventris caspi) fish protein hydrolysates

Whole common Kilka fish was hydrolyzed separately using four commercial enzymes, Alcalase, Neutrase, Protamex at 50 °C and Pepsin at 37 °C for 30, 60 and 90 min. Degree of hydrolysis, angiotensin-I-converting enzyme (ACE) inhibitory activity and antimicrobial activity of each hydrolysate against Gram-negative (Escherichia coli, Salmonella enteritidis) and Gram-positive (Staphylococcus aureus, Listeria innocua) bacteria were studied. Results showed that the degree of hydrolysis for all enzymes was in the range of 2.63–3.36%. Electrophoresis profiles of the Kilka protein hydrolysates showed that most of produced peptides were in the range of 30 D but Alcalase and Neutrase had a better performance in the production of low molecular weight peptides in the range of 10 D. This led to increase the antimicrobial activity against the examined bacteria at the concentration of 200 µg/mL peptide solution. The Neutrase enzyme produced hydrolysate with the highest ACE inhibitory activity (53% ± 1.8 at 500 µg/mL). Antimicrobial activity of Kilka protein hydrolysates using Protamex and Pepsin was lower than the others due to lack of considerable amount of small peptides. The current research has demonstrated that the peptides derived from the enzymatic hydrolysis of Kilka fish protein in optimum conditions are capable of being converted to antimicrobial and antihypertensive agents to be used in functional foods.

Quantitative Structure-Activity Relationship Modeling Coupled with Molecular Docking Analysis in Screening of Angiotensin I-Converting Enzyme Inhibitory Peptides from Qula Casein Hydrolysates Obtained by Two-Enzyme Combination Hydrolysis.

In this study, Qula casein derived from yak milk casein was hydrolyzed using a two-enzyme combination approach, and high angiotensin I-converting enzyme (ACE) inhibitory activity peptides were screened by quantitative structure-activity relationship (QSAR) modeling integrated with molecular docking analysis. Hydrolysates (<3 kDa) derived from combinations of thermolysin + alcalase and thermolysin + proteinase K demonstrated high ACE inhibitory activities. Peptide sequences in hydrolysates derived from these two combinations were identified by liquid chromatography-tandem mass spectrometry (LC-MS/MS). On the basis of the QSAR modeling prediction, a total of 16 peptides were selected for molecular docking analysis. The docking study revealed that four of the peptides (KFPQY, MPFPKYP, MFPPQ, and QWQVL) bound the active site of ACE. These four novel peptides were chemically synthesized, and their IC50 was determined. Among these peptides, KFPQY showed the highest ACE inhibitory activity (IC50 = 12.37 ± 0.43 μM). Our study indicated that Qula casein presents an excellent source to produce ACE inhibitory peptides.

Considering the potential of Lactobacillus rhamnosus for producing Angiotensin I-Converting Enzyme (ACE) inhibitory peptides in fermented camel milk (Indian breed)

Abstract In this study, fermented camel milk was prepared using proteolytic Lactobacillus rhamnosus MTCC 5945 (NS4), which was analyzed for X-prolyl-dipeptidyl aminopeptidase activity and Angiotensin I-Converting Enzyme (ACE) inhibitory activity. The growth conditions (inoculation rate and incubation time) for the production of peptides were optimized using OPA method. Fractionated 3 kDa, 5 kDa and 10 kDa permeate and retentate samples were further analyzed for ACE-inhibitory activity under the optimized growth conditions. Furthermore, 3 kDa and 10 kDa permeate with highest ACE-inhibitory activities and highest percentage of peptides production were subjected to liquid chromatography mass spectrometry and peptide identification using MASCOT software. Novel peptides were identified from fermented camel milk using homology sequence searching in BlastP (NCBI), and Protein information resource database (PIR). The novelty (ACE-inhibitory activity or Antihypertensive activity) of peptides was also confirmed using novelty search in the database of antihypertensive peptides (AHTPDB).

Production and fermentation characteristics of angiotensin-I-converting enzyme inhibitory peptides of goat milk fermented by a novel wild Lactobacillus plantarum 69

Food derived angiotensin-I-converting enzyme (ACE)-inhibitory peptides are normally from products fermented by Lactobacillus helveticus but seldom by other lactic acid bacteria. In this study, a novel wild strain L. plantarum 69 was identified genetically and applied to ferment goat milk with high ACE-inhibitory activity, flourished bacterial population, and ideal flavor. The fermentation condition was optimized with the aid of response surface methodology (RSM). The optimal fermentation condition were temperature of 35 °C, CaCl2 concentration of 0.07%, and Tween-80 concentration of 0.04%. The ACE-inhibitory activity of the fermented product reach 88.91% which was approximately close to the predicted 91.68%. Purification was operated by ultrafiltration, macroporous resin DA201-C, gel chromatography, and reverse-phase high performance liquid chromatography (RP-HPLC), and finally exhibited the ACE-inhibitory activity of 91.62%. Goat milk fermented by L69 successfully survived in gastrointestinal tract and maintained high ACE-inhibitory activity.