anti-ACE Activities Research Articles

Preparation and identification novel angiotensin-converting enzyme-inhibitory peptides derived from fish waste

The purpose of the research is to compare short peptides from different hydrolysates of fish entrails that can inhibit the activity of angiotensin-converting enzyme (ACE). Fish hydrolysates derived from Catfish, Tilapia, and Mackerel entrails were digested by pepsin and passed through the 3kDa cutoff column. The fraction containing peptides shorter than and equal to 3kDa from catfish hydrolysate has the great ability to inhibit ACE activity in converting the substrate (Furanacroloy-Phe-Gly-Gly, FAPGG) and producing FAP and GG as the products of the reaction. The 3kDa filtrate from the catfish hydrolysate had activity like Captopril, a drug for treating hypertension. The 3kDa filtrate derived from the catfish entrail hydrolysate was purified using OFFGEL electrophoresis and then passed through the C18 column. The 3kDa filtrate was separated into two fractions and then these fractions were determined ACE inhibitory activity. The result showed that the fractions containing hydrophilic peptides and others containing hydrophobic peptides possessed inhibitory activity against ACE. Those fractions were analyzed with LCMS/MS for sequencing. The results revealed that synthesized peptides; ASNLHGV, LFKDLR, PGYALQR, and LETAKSR, derived from the catfish hydrolysate showed anti-ACE activity against its substrate.

Influence of sonication pretreatment on antiradical and anti-ACE activity of protein hydrolysates from fermented pork loins

The aim of this study was to assess whether ultrasound treatment (sonification time: 5, 15, and 30 min; constants: ∼40 kHz, ∼2.5 W cm2) can be applied prior to hydrolysis to enhance the anti-radical and angiotensin converting enzyme inhibiting (anti-ACE) effect of the hydrolysates from fermented pork loins. Enzymatic hydrolysis was performed using pepsin, followed by pancreatin. The influence of meat matrix on the course of hydrolysis, shaped using a lactic acid bacteria (LAB)-based starter culture, was also analyzed. It was found that proteases caused a systematic increase in the content of peptides, while pancreatin limited the peptide content in the protein hydrolysate from the loins subjected to spontaneous fermentation. Moreover, for these tests, sonication time had a negligible effect on the peptides content of the hydrolysates. On the other hand, for the sample of LAB-fermented products, both sonication time and stage of hydrolysis promoted the biological activity of the hydrolysates. Samples from the LAB-fermented meat had more peptides at the stage of digestion with pepsin and pancreatin, exhibiting much faster antiradical and anti-ACE activity compared to the control sample. The obtained results suggest that the use of LAB promotes the release of antiradical peptides during the two-step enzymatic hydrolysis, the duration of which can be shortened to achieve satisfactory biofunctionalities. Additional application of sonication pretreatment allows controlling the course of the hydrolysis, as the pro-health, biological effect of some protein-derived sequences is associated with the content of peptides.

Angiotensin-I-Converting Enzyme (ACE)-Inhibitory Peptides from the Collagens of Monkfish (Lophius litulon) Swim Bladders: Isolation, Characterization, Molecular Docking Analysis and Activity Evaluation.

The objective of this study was to isolate and characterize collagen and angiotensin-I-converting enzyme (ACE)-inhibitory (ACEi) peptides from the swim bladders of monkfish (Lophius litulon). Therefore, acid-soluble collagen (ASC-M) and pepsin-soluble collagen (PSC-M) with yields of 4.27 ± 0.22% and 9.54 ± 0.51%, respectively, were extracted from monkfish swim bladders using acid and enzyme methods. The ASC-M and PSC-M contained Gly (325.2 and 314.9 residues/1000 residues, respectively) as the major amino acid, but they had low imino acid content (192.5 and 188.6 residues/1000 residues, respectively) in comparison with collagen from calf skins (CSC) (216.6 residues/1000 residues). The sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) patterns and ultraviolet (UV) absorption spectrums of ASC-M and PSC-M illustrated that they were mainly composed of type I collagen. Subsequently, three ACEi peptides were isolated from a PSC-M hydrolysate prepared via a double-enzyme system (alcalase + neutrase) and identified as SEGPK (MHP6), FDGPY (MHP7) and SPGPW (MHP9), with molecular weights of 516.5, 597.6 and 542.6 Da, respectively. SEGPK, FDGPY and SPGPW displayed remarkable anti-ACE activity, with IC50 values of 0.63, 0.94 and 0.71 mg/mL, respectively. Additionally, a molecular docking assay demonstrated that the affinities of SEGPK, FDGPY and SPGPW with ACE were -7.3, -10.9 and -9.4 kcal/mol, respectively. The remarkable ACEi activity of SEGPK, FDGPY and SPGPW was due to their connection with the active pockets and/or sites of ACE via hydrogen bonding, hydrophobic interaction and electrostatic force. Moreover, SEGPK, FDGPY and SPGPW could protect HUVECs by controlling levels of nitric oxide (NO) and endothelin-1 (ET-1). Therefore, this work provides an effective means for the preparation of collagens and novel ACEi peptides from monkfish swim bladders, and the prepared ACEi peptides, including SEGPK, FDGPY and SPGPW, could serve as natural functional components in the development of health care products to control hypertension.

Impact of ultrasonication on the contents, profiles and biofunctional properties of free and bound phenolics from white desert truffle (Tirmania nivea) and its protein fractions

The molecular and biofunctional properties of protein and phenolic fractions in edible truffles remain largely unknown. This study examined the effect of ultrasonication on the contents, profiles, and bioactive properties of free and bound phenolics (FP and BP) from desert truffle (Tirmania nivea) and its protein fractions. Protein fractions from the Osborne extraction scheme were biochemically and structurally characterized. The albumin fraction showed the highest abundance (16.8%) and yield (35.8%). Total phenolic contents were the highest in non-sonicated samples (3.5–34.1 mg/g), particularly in the albumin fraction and in whole truffle. FP extracted at 30 °C (FP-30 °C) accounted for the largest proportion of total phenolics in all protein fractions, whereas BP-30 °C and FP-60 °C were predominant in non-sonicated and sonicated truffle, respectively. The highest antioxidant activity was obtained with FP-30 °C extracts from non-sonicated albumins, globulins and truffle (91.9, 72.7 and 30.0%), followed by BP-30 °C from non-sonicated albumins (25.4%) and FP-60 °C from sonicated glutelins-1 (24.2%). High inhibition of α-amylase was evidenced in several extracts, including FP-30 °C from non-sonicated glutelins-1 (99.2%) and FP-30 °C from sonicated globulins (72.4%). Several extracts also displayed high inhibition of angiotensin I-converting enzyme (ACE), including FP-60 °C from non-sonicated glutelins-1 (65.1%) and sonicated glutelins-1 (71.1%) and globulins (64.7%). Most extracts were rich in epicatechin, gallic acid, chlorogenic acid and catechin. Correlations between phenolic content, antioxidant activity, anti-α-amylase and anti-ACE activities were influenced by sonication. Sonication reduced the particle size of the proteins and modified their structural characteristics. These findings demonstrate that white desert truffle proteins co-occur with bioactive phenolics whose functionalities can be tailored by protein fractionation and sonication.

Impact of Harvest Month and Drying Process on the Nutritional and Bioactive Properties of Wild Palmaria palmata from Atlantic Canada.

The macroalga Palmaria palmata could be a sustainable and nutritional food resource. However, its composition may vary according to its environment and to processing methods used. To investigate these variations, wild P. palmata from Quebec were harvested in October 2019 and June 2020, and dried (40 °C, ≃5 h) or stored as frozen controls (-80 °C). The chemical (lipids, proteins, ash, carbohydrates, fibers), mineral (I, K, Na, Ca, Mg, Fe), potential bioactive compound (carotenoids, polyphenols, β-carotene, α-tocopherol) compositions, and the in vitro antioxidant activity and angiotensin-converting enzyme (ACE) inhibition potential of water-soluble extracts were determined. The results suggested a more favorable macroalgae composition in June with a higher content of most nutrients, minerals, and bioactive compounds. October specimens were richer only in carbohydrates and carotenoids. No significant differences in antioxidant or anti-ACE inhibitory activities were found between the two harvest months. The drying process did not significantly impact the chemical and mineral compositions, resulting in only small variations. However, drying had negative impacts on polyphenols and anti-ACE activities in June, and on carotenoids in October. In addition, a concentration effect was observed for carotenoids, β-carotene and α-tocopherol in June. To provide macroalgae of the highest nutritional quality, the drying process for June specimens should be selected.

Identification of Gastrointestinal Digestion Stable Antihypertensive Fish Peptides from Atlantic Mackerel (Scomber scombrus).

High blood pressure has been recognized as one of the main risk factors of cardiometabolic syndrome by health organizations. Hypertension is medicated by various classes of synthetic drugs; however, adverse effects have repeatedly been reported. Moreover, natural alternatives such as fish peptides have been effective in the treatment and prevention of hypertension. The aim of our study was to fractionate and identify antihypertensive peptides. Fractions were produced using different techniques of solid-phase extraction (SPE), pressure-driven ultrafiltration (UF), and electro04dialysis with UF membrane. According to our results, the hydrophobic fraction of SPE (IC50 5 μg) was the most potent anti-angiotensin converting enzyme (ACE) product. Findings of the study suggest that the separation technique plays an important role in the isolation efficiency of antihypertensive biopeptides. Importantly, the hydrophobic fraction's activity was retained through a static model of an in vitro gastrointestinal digestion system. In conclusion, polarity regardless of charge and size was the most important factor for anti-ACE activity of an Atlantic mackerel biopeptide. In addition, the presence of leucine at either of the extremities (C- or N-terminal) and/or leucine-rich motifs could well explain the hypotensive effect of our active fraction.

Screening for probiotic attributes of lactic acid bacteria isolated from human milk and evaluation of their anti-diabetic potentials

ABSTRACT Lactic acid bacteria (LAB) have gained much attention recently due to their probiotic attributes with anti-ACE and anti-glycation potentials targeting management of diabetes. This study was designed to isolate LAB from human milk and to evaluate their potential for inhibitory activities on ACE and AGEs formation using in vitro assay models. Among 12 LAB isolates, many strains exhibited strong probiotic attributes including tolerance to low pH, high salt, gastric, and intestinal juices with higher cell adhesion. Further, cell-free extracts of LAB tested for in vitro anti-ACE and anti-AGEs activities evidenced Lacticaseibacillus casei MKU1, Lacticaseibacillus paracasei MKU2, Lactiplantibacillus pentosus MKU3, L. paracasei MKU7, L. delbrueckii GERU3 and Lactobacillus delbrueckii MKU10 as strong ACE and AGEs inhibitors. Subsequently, Principal Component Analysis showed a positive correlation with anti-ACE (p ≤ .01) and anti-glycation (p ≤ .05) activity of LAB. Overall, this study suggests that six Lactobacillus isolates of human milk with superior probiotic attributes looks promising as potential probiotic strains.

Codonopsis pilosula and fish collagen yogurt: Proteolytic, potential Angiotensin-I converting enzyme (ACE) inhibitory activity and sensory properties

The effects of Codonopsis pilosula (CP) and/or fish collagen (FC) on post-acidification, proteolysis of milk proteins, angiotensin-I converting enzyme (ACE) inhibitory activity, and sensory evaluation were investigated in yogurt during 0, 7, & 21 days of storage at 4 °C. Two groups of yogurt samples were prepared: group 1 included plain yogurt (control) and CP-yogurt; group 2 included plain yogurt + FC (control) and CP-yogurt + FC. CP- yogurt showed a significant increase in total titratable acidity (TTA) on day 7 of storage. The presence of FC in yogurt significantly improved (p < 0.05) the content of free amino acids (FAA) compared to the absence. O-phthaldialdehyde (OPA) peptide concentration increased (p < 0.05) to the highest amount for CP-yogurt ± FC on day 7 of storage. In addition, more degradation was observed in bovine serum albumin (BSA), α-, β-, & κ-caseins, β-lactoglobulin, and α-lactalbumin of CP- yogurt + FC than its control on day 7 of storage. CP- yogurt with/without FC showed higher (p < 0.05) inhibitory ACE activity than their respective controls on day 7 of storage. The addition of fish collagen in CP- yogurt seemed to have good scoring in sensory evaluation. In conclusion, the presence of C. pilosula and fish collagen in the yogurt can bring about promising health benefits such as anti-ACE activity.

Effects of medicinal plants extract enriched cheese with fish collagen on proteolysis and in vitro angiotensin-I converting enzyme inhibitory activity

The effects of Illicium verum-, Psidium guajava-, or Curcuma longa- and/or fish collagen cheese on the proteolytic activity with anti-ACE activity were investigated during 0, 14, and 28 days of ripening. Two groups of plant-based cheeses were prepared. The first group contained plain cheese (control), I. verum-, P. guajava-, or C. longa-cheese. The second group contained plain cheese + fish collagen (control), I. verum-, P. guajava-, or C. longa-cheeses with fish collagen. I. verum and C. longa increased (p < 0.05) the peptides content in cheese to 499.53 ± 10.11, and 340.48 ± 1.64 μg/g respectively on day 28 as compared to plain cheese (274.9 ± 8.95 μg/g). Fish collagen improved (p < 0.05) the peptide content in P. guajava-, and C. longa-cheese compared to control on day 14 of storage. P. guajava- and C. longa-cheese showed a significant increase in ACE-I inhibitory activity on day 28 (∼80%; p < 0.05). Fish collagen enhanced (p < 0.05) anti-ACE-I peptides in I. verum- and P. guajava-cheese (88% and 85%; respectively) during 14 days of ripening. It is possible to develop cheeses with anti-ACE properties by using the three types of plant cheese either with or without fish collagen.

Effects of herbal yogurt with fish collagen on bioactive peptides with angiotensin-I converting enzyme inhibitory activity

Illicium verum (IV; dried fruit), Psidium guajava (PG; dried leaves), and Curcuma longa (CL; dried rhizome) water extract and/or fish collagen were added into yogurt to determine their effects on acidification and the proteolysis of milk up to 21 days of storage at 4°C. The angiotensin-I converting enzyme (ACE) test was conducted to analyze the inhibitory activity of bioactive peptides produced during proteolytic activity on the ACE enzyme. The addition of fish collagen in PG- yogurt significantly decreased pH compared to control on day 7 of storage. The presence of IV, PG, and CL enhanced (p<0.05) OPA peptide amount during 7 & 14 days of storage. The highest ACE inhibitory activity was shown on day 7 for all herbal yogurt. Herbal yogurt either in the presence or absence of fish collagen may improve the manufacture and formulation of yogurt with anti-ACE activity.

Antihypertensive Peptides from Ultrafiltration and Fermentation of the Ricotta Cheese Exhausted Whey: Design and Characterization of a Functional Ricotta Cheese.

Aiming at valorizing the ricotta cheese exhausted whey (RCEW), one of the most abundant by-products from the dairy industry, a biotechnological protocol to obtain bioactive peptides with angiotensin-I-converting enzyme (ACE)—inhibitory activity was set up. The approach was based on the combination of membrane filtration and fermentation. A Lactobacillus helveticus strain selected to be used as starter for the fermentation of the ultrafiltration protein-rich retentate (R-UF) obtained from RCEW. The fermented R-UF was characterized by a high anti-ACE activity. Peptides responsible for the bioactivity were purified and identified through nano-LC–ESI–MS/MS. The sequences identified in the purified active fractions of the fermented R-UF showed partial or complete overlapping with previously reported κ-casein antihypertensive fragments. The fermented R-UF was spray-dried and used to enrich ricotta cheese at different fortification level (1 and 5% w/w). An integrated approach including the assessment of the microbiological, chemical, functional, textural, and sensory properties was used to characterize the fortified products. A significantly higher anti-ACE activity was found in the ricotta cheese fortified with fermented R-UF as compared to the control and to the samples obtained with the unfermented R-UF fraction at the same levels of fortification. In particular, a 100 g portion of the ricotta cheese produced at 5% fortification level contained circa 30 mg of bioactive peptides. The fortification led to a moderate acidification, increased hardness and chewiness, and decreased the milk odor and taste of the ricotta cheese as compared to the control, while flavor persistence and sapidity improved.

Potensi Ekstrak Etanol Ubi Jalar Ungu sebagai Inhibitor Angiotensin Converting Enzyme pada Tikus Hipertensi

There is an increasing amount of evidence that oxidative stress related to hypertension can damage the function of diverse structures such as the aorta and kidney. It is a well-established fact that chlorogenic acid and anthocyanin found in purple sweet potato generates bioactive compound with antihypertensive and anti-ACE activities in RAA system. The present study sought to investigate anti-ACE activities in RAA system of extract ethanol of purple sweet potato (EP) in deoxycorticosterone acetate (DOCA–salt)–induced hypertensive rats (Rattus norvegicus). The rats were orally administrated a 95% ethanol extract of purple sweet potato (var. ayamurasaki) (EP) in a daily dose of 200 and 400 mg/kg body weight also chlorogenic acid (CA) of 700 mg/kg bw for 4 weeks. Activity of renin, ACE, and Ang II concentration were assessed. Inhibiting activity of renin, ACE, and decreasing Ang II concentration after treatment was observed in the DOCA-salt hypertensive rats compared to normotensive group rats; (P&lt;0.05). This is the first report that demonstrates the lowering of blood pressure and anti-ACE in RAA-system effects of an ethanol extract of purple sweet potato, containing chlorogenic acid, in a DOCA–salt model of hypertension.

Proteolytic profile, angiotensin-I converting enzyme inhibitory activity and sensory evaluation of Codonopsis pilosula and fish collagen cheese

Four types of cheeses were prepared included plain- cheese (control), Codonopsis pilosula (CP)- cheese, plain- cheese with fish collagen (FC; control) and CP- cheese with FC. The effects of cheese samples on acidification, proteolysis of milk proteins using three methods (cadmium-ninhydrin method, O-phthaldialdehyde (OPA) assay, and electrophoresis assay), and angiotensin-converting enzyme (ACE)-inhibitory activity were investigated during 0, 2, & 4 weeks of ripening. In addition, the sensory evaluation was also investigated during 0, 2, 4, & 8 weeks of ripening. The presence of FC in CP- cheese increased the numbers of free amino acids (FAA) at 0 and 2 weeks. The addition of CP both in the presence and absence of FC affected positively (p < 0.05) on the concentrations of OPA peptide in cheese compared to their respective controls. The presence of CP and/or FC in cheese increased the degradation of milk proteins (α-, β-, & κ- caseins, β-lactoglobulin, and α-lactalbumin) compared to their respective controls during ripening periods. The highest ACE inhibitory activity was shown at 4 weeks of ripening for CP- cheese both in the absence (67.75 ± 14.15%) and the presence (78.65 ± 2.85%) of FC. In addition, 8-week-old CP-cheese in the presence and absence of fish collagen had similar organoleptic characteristics to plain-cheese. In conclusion, C. pilosula and/or fish collagen may lead to the development in the production and formulation of cheese with anti-ACE activity.

Effects of Lycium barbarum and fish collagen in cheese on the proteolytic degradation profile with anti‐ACE activity

The effects of L. barbarum (LB) and/or fish collagen (FC) in cheese on the proteolytic degradation profile with anti-ACE activity were investigated. Four types of cheeses were made plain cheese (control), LB-cheese, FC-cheese (control), and LB-cheese + FC. Acidification of cheese, milk proteins proteolysis, and angiotensin-converting enzyme (ACE) inhibitory activity was performed for 28 days. The OPA peptides content of LB-cheese was higher (p < .05) than control on 28 days. The addition of FC in LB-cheese improved OPA peptides’ content. The proteins degradation of β-lactoglobulin, α- and β-caseins increased in the presence of LB in cheese whereas α- and β-caseins degradation improved in LB + FC cheese. ACE inhibitory activity was decreased (p < .05) in LB-cheese but not in LB + FC. The combination of LB and FC in cheese showed the most enhancements on the production of peptides that may act as an anti-ACE activity. Novelty impact statement ACE inhibitory peptides from cheese could be considered as a potential approach for use in nutraceuticals for the prevention and management of hypertension. People have a high demand to consume functional dairy products and there are big opportunities for the functional dairy market, this has driven the cheese industry to the development of commercial new products in the market. L. barbarum and fish collagen contain significant amounts of biologically active compounds that can be formulated into cheese to provide health properties such as anti-ACE activity.

The Effect of Steaming and Fermentation on Nutritive Values, Antioxidant Activities, and Inhibitory Properties of Tea Leaves.

Fermented tea (Cha-miang in Thai) is a local product made by traditional food preservation processes in Northern Thailand that involve steaming fresh tea leaves followed by fermenting in the dark. Information on changes in nutritive values, bioactive compounds, antioxidant activities, and health properties that occur during the steaming and fermenting processes of tea leaves is, however, limited. Changes in nutritive values, phenolics, antioxidant activities, and in vitro health properties through inhibition of key enzymes that control obesity (lipase), diabetes (α-amylase and α-glucosidase), hypertension (angiotensin-converting enzyme (ACE)), and Alzheimer’s disease (cholinesterases (ChEs) and β-secretase (BACE-1)) of fermented tea were compared to the corresponding fresh and steamed tea leaves. Results showed that energy, carbohydrate, and vitamin B1 increased after steaming, while most nutrients including protein, dietary fiber, vitamins (B2, B3, and C), and minerals (Na, K, Ca, Mg, Fe, and Zn) decreased after the steaming process. After fermentation, energy, fat, sodium, potassium, and iron contents increased, while calcium and vitamins (B1, B2, B3, and C) decreased compared to steamed tea leaves. However, the contents of vitamin B1 and iron were insignificantly different between fresh and fermented tea leaves. Five flavonoids (quercetin, kaempferol, cyanidin, myricetin, and apigenin) and three phenolic acids (gallic acid, caffeic acid, and p-coumaric acid) were identified in the tea samples. Total phenolic content (TPC) and antioxidant activities increased significantly after steaming and fermentation, suggesting structural changes in bioactive compounds during these processes. Steamed tea exhibited high inhibition against lipase, α-amylase, and α-glucosidase, while fermented tea possessed high anti-ChE and anti-ACE activities. Fresh tea exhibited high BACE-1 inhibitory activity. Results suggest that tea preparations (steaming and fermentation) play a significant role in the amounts of nutrients and bioactive compounds, which, in turn, affect the in vitro health properties. Knowledge gained from this research will support future investigations on in vivo health properties of fermented tea, as well as promote future food development of fermented tea as a healthy food.

Flavanones biotransformation of citrus by-products improves antioxidant and ACE inhibitory activities in vitro

The enzymatic biotransformation effects of tannase/β-glucosidase on phenolic profile, antioxidant capacity, and angiotensin-converting enzyme (ACE) inhibitory activity of extracts from two citrus industry wastes were studied. Hesperidin and hesperetin ACE inhibitory activity were also measured. The major phenolic in crude extracts was hesperidin, whereas it was hesperetin after being biotransformed. Antioxidant capacity and ACE inhibitory activity of enzyme-treated extracts were significantly higher. Citrus pectin residue extracts treated with enzymes (CPRTB) had the highest antioxidant and anti-ACE activities (FRAP = 298±3 μmolTE mg−1, DPPH = 230 ± 10 μmolTE mg−1, IC50 = 0.21 mg mL−1, IE = 100%), and the highest hesperetin content (42.7 mg g−1). Hesperetin standard solution showed higher anti-ACE activity than hesperidin (IE = 82.8–100% and 62–76%, respectively). Despite the lower flavanone concentration in CPRTB compared to the 1000μMhesperetin solution, both had the same anti-ACE activity, suggesting that the bioactivity of citrus extracts is due to the synergism of different phenolic compounds. Enzymatic biotransformation resulted in the production of extracts with increased anti-hypertension activities and might potentially be used to develop value-added products.

Influence of Sonication and Taraxacum Officinale Addition on the Antioxidant and Anti-ACE Activity of Protein Extracts from Sous Vide Beef Marinated with Sour Milk and after In Vitro Digestion

The present study assessed the effect of pretreating beef as a raw material for sous vide steak preparation. The pretreatment involved maceration of a batch of meat in sour milk with the simultaneous use of ultrasound (250 or 500 W) as well as the addition of Taraxacum officinale. The biological activity profile of the peptides was assessed in terms of their antioxidant activity and inhibiting activity against angiotensin-converting enzyme (ACE). Changes in the biological activity of peptides under the influence of hydrolysis by gastrointestinal enzymes, i.e., pepsin and pancreatin, were also considered. There was no significant effect of T. officinale addition and sonication of beef batches on the protein content (except for lot S6, after sonication at 500 W as acoustic power and with the addition of dandelion). It was observed that the interaction of maceration in sour milk with simultaneous ultrasound treatment as the initial production step of sous vide beef steak generates the formation of peptides with antioxidant properties. Moreover, peptide formation can be further enhanced by adding dandelion (based on the results of antiradical and chelating activity tests). In addition, the progression of hydrolysis under the influence of gastrointestinal enzymes promotes the release of peptides with antioxidant and anti-ACE activity.

In vitro study on novel bioactive peptides with antioxidant and antihypertensive properties from edible rhizomes

Rhizome proteins of white turmeric, turmeric and ginger were hydrolyzed using pepsin and trypsin. The peptides from crude hydrolysates were purified based on antihypertensive and antioxidant activities. The peptide sequences were determined by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The binding energy with ACE of each antihypertensive peptides was predicted by in silico docking. Among the 11 bioactive peptides selected from the three rhizomes, five peptides from ginger harbored both antioxidant and anti-ACE activities. Particularly potent was the VTYM peptide from ginger, with the lowest IC50 and EC50 values of 16.4 ± 0.4 μmol/L, 19.9 ± 2.1 μmol/L and 24.0 ± 3.7 μmol/L in antihypertensive, DPPH, and ABTS assays, respectively. In addition, VTYM was capable of protecting Agrobacterium tumefaciens sodBI sodBII sodBIII triple mutant against menadione treatment. Among turmeric-derived peptides, CGVGAA, DVDP, and CACGGV exhibited strong anti-hypertensive activities, with IC50 values of 18.3 ± 0.1 μmol/L, 19.0 ± 0.6 μmol/L and 25.0 ± 0.2 μmol/L, respectively. Hence, this study demonstrates that many edible rhizomes, apart from serving as valuable sources of essential oil and bioactive metabolites, are also bountiful sources of bioactive peptides that can be harnessed for the benefits of human health.

Effects of fermentation periods on antioxidant and angiotensin I-converting enzyme inhibitory activities of peptides from fish sauce by-products

Manufacturing of fish sauce results in a large number of underutilized by-products. The fish sauce by-products (FSBs) contain peptides derived from enzymatic hydrolysis of the fish proteins by proteases from their gastrointestinal tract and halophilic microorganisms. Commercial fish sauce can be divided into different grades based on their fermentation period. The 1st, 2nd and 3rd grade FSBs are solid wastes produced after the 1st, 2nd and 3rd grade fish sauce fermentation. This work aims to evaluate the effect of fermentation periods on antioxidant and angiotensin I-converting enzyme (ACE) inhibitory activities of the FSBs. Based on bioassays against different mechanisms, the 1st grade FSB possessed stronger DPPH and hydroxyl radical scavenging activities and reducing ability than the 2nd and 3rd grades. The top two grades of FSB showed higher % ACE inhibition than the 3rd grade FSB. All FSBs had equally strong H2O2 quenching and iron chelating abilities. It was observed that FSB fractions with smaller molecular weight and higher hydrophobicity possessed higher antioxidant and anti-ACE activities. This work demonstrated that the manufacturing fermentation time affected activities of FSB peptides. Understanding of composition and bioactivities of the FSBs may lead to the development of value-added functional products from these manufacturing wastes.

The effects of Lycium barbarum water extract and fish collagen on milk proteolysis and in vitro angiotensin I-converting enzyme inhibitory activity of yogurt.

Plain and Lycium barbarum yogurt were made in the presence and absence of fish collagen. Yogurt samples were analyzed for acidification, milk protein proteolysis, angiotensin I-converting enzyme (ACE) inhibitory activity, and sensory evaluation during refrigerated storage for up to 21 days. The o-phthaldialdehyde peptides amount of L. barbarum yogurt both in the presence and absence of fish collagen were significantly increased during 14 days of storage. SDS-PAGE showed improvement in whey proteins degradation of L. barbarum yogurt with/without fish collagen after 3 weeks of storage. L. barbarum yogurt in absence of fish collagen was acting as a great ACE inhibitor reached up to 85% on day 7 of storage. The incorporation of L. barbarum and/or fish collagen affected to a small extent the overall sensory characteristics of yogurt. Yogurt supplemented with L. barbarum and/or fish collagen may lead to the improvement in the production and formulation of yogurt differing in their anti-ACE activity.