Angiotensin I-converting Enzyme Activity Research Articles

Protein hydrolysates with ACE-I inhibitory activity from amaranth seeds fermented with Enterococcus faecium-LR9: Identification of peptides and molecular docking

One of the causes of hypertension is the activity of angiotensin-I converting enzyme (ACEI), making its inhibition a crucial strategy for controlling the disease. Protein hydrolysates are a known source of bioactive peptides that contribute to ACE-I inhibition. This study aims to evaluate the ACE-I inhibitory activity of amaranth seed hydrolysates after fermentation with Enterococcus faecium-LR9 and to compare it with Leuconostoc mesenteroides-18C6 and enzymatic hydrolysis (Alcalase®). The fermentation strategy with LR9 proved to be more effective in inhibiting ACE-I (79.1 ± 2.6 %) in vitro compared to 18C6 (68.0 ± 9.8 %) and enzymatic hydrolysis (69.4 ± 1.2 %). Consequently, these protein hydrolysates were subjected to in silico analysis, identifying 125 novel peptides. Bioinformatics and molecular docking analyses revealed 10 peptides with high ACE-I inhibitory potential. Among them, the IFQFPKTY and VIKPPSRAW peptides stood out. Therefore, E. faecium-LR9 is a promising strain for the release of bioactive peptides from seed storage proteins.

The Antioxidant Effects of Trypsin-Hydrolysate Derived from Abalone Viscera and Fishery By-Products, and the Angiotensin-I Converting Enzyme (ACE) Inhibitory Activity of Its Purified Bioactive Peptides.

Abalone is a rich source of nutrition, the viscera of which are discarded as by-product during processing. This study explored the biological activities of peptides derived from abalone viscera (AV). Trypsin-hydrolysate of AV (TAV) was purified into three fractions using a Sephadex G-10 column. Nine bioactive peptides (VAR, NYER, LGPY, VTPGLQY, QFPVGR, LGEW, QLQFPVGR, LDW, and NLGEW) derived from TAV-F2 were sequenced. LGPY, VTPGLQY, LGEW, LDW, and NLGEW exhibited antioxidant properties, with IC50 values of 0.213, 0.297, 0.289, 0.363, and 0.303 mg/mL, respectively. In vitro analysis determined that the peptides VAR, NYER, VTPGLQY, QFPVGR, LGEW, QLQFPVGR, and NLGEW inhibited ACE, with IC50 values of 0.104, 0.107, 0.023, 0.023, 0.165, 0.004, and 0.146 mg/mL, respectively. The binding interactions of ACE-bioactive peptide complexes were investigated using docking analysis with the ZDCOK server. VTPGLQT interacted with HIS513 and TYR523, and QLQFPVGR interacted with HIS353, ALA354, GLU384, HIS513, and TYR523, contributing to the inhibition of ACE activity. They also interacted with amino acids that contribute to stability by binding to zinc ions. QFPVGR may form complexes with ACE surface sites, suggesting indirect inhibition. These results indicate that AV is a potential source of bioactive peptides with dual antioxidant and anti-hypertensive dual effects.

Computational Study of Molecular Mechanism for the Involvement of Human Serum Albumin in the Renin–Angiotensin–Aldosterone System

Human serum albumin (HSA) is an endogenous inhibitor of angiotensin I-converting enzyme (ACE) and, thus, plays a key role in the renin–angiotensin–aldosterone system (RAAS). However, little is known about the mechanism of interaction between these proteins, and the structure of the HSA–ACE complex has not yet been obtained experimentally. The purpose of the presented work is to apply computer modeling methods to study the interaction of HSA with ACE in order to obtain preliminary details about the mechanism of their interaction. Ten possible HSA–ACE complexes were obtained by the procedure of macromolecular docking. Based on the number of steric and polar contacts between the proteins, three leading complexes were selected, the stabilities of which were then tested by molecular dynamics (MD) simulation. Based on the results of MD simulation, the two most probable conformations of the HSA–ACE complex were selected. The analysis of these conformations revealed that the processes of oxidation of the thiol group of Cys34 of HSA and the binding of albumin to ACE can reciprocally affect each other. Known point mutations in the albumin molecules Glu82Lys, Arg114Gly, Glu505Lys, Glu565Lys and Lys573Glu can also affect the interaction with ACE. According to the result of MD simulation, the known ACE mutations, albeit associated with various diseases, do not affect the HSA–ACE interaction. A comparative analysis was performed of the resulting HSA–ACE complexes with those obtained by AlphaFold 3 as well as with the crystal structure of the HSA and the neonatal Fc receptor (FcRn) complex. It was found that domains DI and DIII of albumin are involved in binding both ACE and FcRn. The obtained results of molecular modeling outline the direction for further study of the mechanisms of HSA–ACE interaction in vitro. Information about these mechanisms will help in the design and improvement of pharmacotherapy aimed at modulation of the physiological activity of ACE.

Comparative efficacy of amino acid availability and peptidomic analysis of alternative proteins from different sources under dynamic in vitro protein digestion

The increasing global demand for animal protein highlights the critical necessity of exploring alternative protein sources. Accessing the nutritional characteristics of emerging alternative proteins is vital for food processing and consumer acceptance. This study investigated the amino acid availability and peptidomics profiles of plant- (soy), fungal- (filamentous fungus Fusarium venenatum), microalgae- (Nannochloropsis oculata), and insect-based (black soldier fly) proteins using an advanced dynamic in vitro digestion system, with whey protein as a reference. After gastric digestion, soy and mycelial proteins, despite displaying distinct microstructures, exhibited slightly higher protein digestibility levels of 28.79% and 26.36%, respectively, compared to whey protein (22.39%). However, following small intestinal digestion, whey protein (61.31%) significantly outperformed alternative proteins. Mycelial protein (43.71%) exhibited digestibility similar to soy protein (46.12%), markedly surpassing both microalgae protein (33.35%) and insect protein (26.58%). Notably, insect protein achieved an amino acid availability nearly approaching that of whey protein, underscoring its substantial proteolysis capability. Furthermore, microalgae protein produced the highest percentage and number of bioactive peptides under simulated digestion, suggesting potential health benefits such as angiotensin I-converting enzyme (ACE) and dipeptidyl peptidase-IV (DPP-IV) inhibitor activities, which could mitigate the risk of hypertension and Type 2 diabetes. Alternative proteins from different sources demonstrate diverse digestive mechanisms and proteolysis profiles, thereby bolstering their potential applications as nutritious food ingredients in the future.

Effect of Various Fruit Extracts on Angiotensin I-Converting Enzyme (ACE) and Kallikrein (KLK) Activities.

Hypertension is one of the main risk factors for cardiovascular disease and causes widespread morbidity and mortality worldwide. The aim of this work was to screen the fruit with high angiotensin I-converting enzyme (ACE) inhibitory activity and kallikrein (KLK) promotion activity by three different extraction methods from 22 kinds of fruits. Results showed that the aqueous extracts of fresh kiwifruit significantly inhibited ACE activity (47.71%), whereas the KLK activity was also inhibited (4.56%). This indicated that the substances inhibiting ACE activity existed in kiwifruit might be small molecular substances such as polyphenols. The nonpolar substance existed in the ethanol extracts of grape inhibited ACE activity significantly. The enzymatic hydrolysates of red grape significantly promoted KLK activity, whereas its ethanol extracts significantly inhibited KLK activity. This results suggested that the components that lower blood pressure and raise blood pressure are generally presented in the same fruit, the former are mostly water-soluble substances, while the latter are generally alcohol-soluble substances. If certain or individual components can be isolated from edible fruits, they may significantly affect blood pressure in humans.

Chemical characterization and angiotensin-I converting enzyme inhibitory activity of Indonesian stinky beans

The chemical composition of four Indonesian stinky beans has been explored. Those bean are Petai (Parkia speciosa), Lamtoro Gung (Leucaena leucochepala ssp. Glabrata (Rose) S. Zarate), Jengkol (Pithecellobium jiringa) and Kabau (Archidendron bubalinum). This exploration belongs to the local food utilization research theme of functional food sources. Those beans have a unique flavour and usually lead to foul stools, sweat, urine or mouth odour. Their intense flavour may be due to the content of amino acids. High hydrophobic and negative charge hydrophilic amino acids are crucial in preventing hypertension through inhibition of angiotensin I-converting enzyme (ACE) activity. This study evaluated the chemical properties of beans and its angiotensin I-converting enzyme inhibitory (ACE-I) peptides. The amino acid profile was determined as preliminary data to ensure the content of hydrophobic and negative charge hydrophilic amino acids. Their ability to inhibit ACE was studied to represent an antihypertensive effect. In vitro gastrointestinal digestion was applied to obtain more small molecular peptides and evaluate their ACE-I activity after digestion. Petai has the highest glutamic acid (20.90 g/100 g protein d.b.), lysine (13.31 g/100 g protein d.b.), arginine (11.76 g/100 g protein d.b.), leucine (10.98 g/100 g protein d.b.), and aspartic acid (10.72 g/100 g protein d.b.). Fresh Jengkol has the highest ACE-I activity (67.59%). Subsequential digestion by pepsin and pancreatin improves the ACE-I activity, and Kabau had the highest (79.87%). Based on the results, Indonesian stinky beans can prevent hypertension by inhibiting ACE activity and being used as a protein source alternative

Infection by zika virus increase angiotensin I-converting enzyme activity in mouse brain

Congenital zika virus syndrome (CZS) has become a significant worldwide concern since the sudden rise of microcephaly related to zika virus (ZIKV) in Brazil. Primarily transmitted by Aedes mosquitoes, ZIKV shares serologic similarities with dengue virus (DENV), complicating the diagnosis and/or clinical management. The Angiotensin I-Converting Enzyme (ACE) was associated with either neuroprotective or anti-inflammatory properties in the central nervous system (CNS). The possible role(s) of ACE in these two flaviviruses infection remain largely unexplored. In this study, we evaluate ACE activity in the brain of ZIKV- or DENV-infected mice, both compared to MOCK, showing about 30 % increased ACE activity only in ZIKV-infected mice (p = 0.024), while no change was noticed in brain from DENV-infected animals (p = 0.888). In addition, the treatment with interferon beta (IFNβ), under conditions previously demonstrated to rescue the normal size of microcephalic brains determined by ZIKV infection, also restored ACE activity in ZIKV-infected animals to levels close to that of the MOCK control group. Although inflammatory responses expected for either ZIKV or DENV infections, only ZIKV was associated with microcephaly, as well as with increased ACE activity and reversion by treatment with IFNβ. Furthermore, this increase in ACE activity was observed only after intracerebroventricular (ICV) injection (F (2, 16) = 7.907, p = 0.004), but not for intraperitoneal (IP) administration of ZIKV (F (2, 26) = 1.996, p = 0.156), suggesting that the observed central ACE activity modulation may be associated with the presence of this specific flavivirus in the brain.

Nicotianamine as a Potential Active Component of Lotus Seed Extract for Inhibiting Angiotensin-converting Enzyme

Aims: Hypertension is one of the chronic diseases causing a serious health problem in many countries worldwide. Therefore, the prevention and amelioration of hypertension with medicinal food is considered to be important for maintaining good health and well-being. The main objective of this study is to verify that the extract of lotus seed has a significant inhibitory effect on the angiotensin I-converting enzyme (ACE). Background: Lotus (Nelumbo nucifera) is well known to have a variety of biological and med-ical activities and is popularly used as a traditional medicinal food in several East Asian coun-tries. In a previous study, we reported that the aqueous extract of lotus root used as a popular foodstuff caused an inhibitory effect on the angiotensin I-converting enzyme (ACE), suggesting its possible effectiveness for improving high blood pressure. Objective: The purpose of the present study was to reveal the effect of lotus seed extract on ACE activity and to identify a potentially active component of the extract originating from lotus seed. Methods: The ACE inhibitory activity was determined using Hippuryl-L-histidyl-L-leucin (HHL) as substrate, and the amount of hippuric acid formed enzymatically was determined using an HPLC system. Results: The lotus seed extract was shown to strongly inhibit the ACE activity, thus ameliorating the hypertensive state. Furthermore, the fractionation of the lotus seed extract provided evidence for suggesting nicotianamine as a putative ACE-inhibiting component contained in the extract. Conclusion: These findings were considered to propose the possibility that the lotus seed and the lotus root might benefit patients with hypertension.

Inhibitory activity of Angiotensin-I converting enzyme (ACE-I) from partially purified Phaseolus lunatus peptide fractions

Phaseolus lunatus have proven to be a likely source of peptides with bioactivities that could be used to prevent and treat chronic degenerative diseases like arterial hypertension (AHT). Angiotensin-I converting enzyme (ACE-I) inhibition is essential for the AHT pathophysiology. In this work, the kinetic study of inhibition and inhibitory activity of ACE-I from peptide fractions partially purified from a protein hydrolysate from Phaseolus lunatus was performed. Hydrolysis was done by sequential enzymatic treatments with Pepsin-Pancreatin. The hydrolysates were ultrafiltered with 3 kDa and 5 kDa membranes, obtaining a fraction of 3–5 kDa which was later purified by gel filtration chromatography (GFC) and high-performance liquid chromatography (HPLC). The GFC fractions exhibited ACE-I inhibitory activities (ACE-I_I) up to 37.86% with an IC50 of 6.34 μg/mL. From HPLC purification, ACE-I_I up to 26.23% were obtained with an IC50 of 2.69 μg/mL. The kinetic parameters of the inhibition indicated that the peptides inhibit ACE-I through a competitive mechanism. The amino acids of the fractions evaluated presented Pro, Ala, Leu, and Ile, which can be part of the peptide fractions with ACE-I_I; with these results obtained these peptides could be used as functional foods related to the control and prevention of diseases related to AHT.

Carriers of Heterozygous Loss-of-Function ACE Mutations Are at Risk for Alzheimer's Disease.

We hypothesized that subjects with heterozygous loss-of-function (LoF) ACE mutations are at risk for Alzheimer's disease because amyloid Aβ42, a primary component of the protein aggregates that accumulate in the brains of AD patients, is cleaved by ACE (angiotensin I-converting enzyme). Thus, decreased ACE activity in the brain, either due to genetic mutation or the effects of ACE inhibitors, could be a risk factor for AD. To explore this hypothesis in the current study, existing SNP databases were analyzed for LoF ACE mutations using four predicting tools, including PolyPhen-2, and compared with the topology of known ACE mutations already associated with AD. The combined frequency of >400 of these LoF-damaging ACE mutations in the general population is quite significant-up to 5%-comparable to the frequency of AD in the population > 70 y.o., which indicates that the contribution of low ACE in the development of AD could be under appreciated. Our analysis suggests several mechanisms by which ACE mutations may be associated with Alzheimer's disease. Systematic analysis of blood ACE levels in patients with all ACE mutations is likely to have clinical significance because available sequencing data will help detect persons with increased risk of late-onset Alzheimer's disease. Patients with transport-deficient ACE mutations (about 20% of damaging ACE mutations) may benefit from preventive or therapeutic treatment with a combination of chemical and pharmacological (e.g., centrally acting ACE inhibitors) chaperones and proteosome inhibitors to restore impaired surface ACE expression, as was shown previously by our group for another transport-deficient ACE mutation-Q1069R.

ACE inhibitory peptides from enzymatic hydrolysate of fermented black sesame seed: Random forest-based optimization, screening, and molecular docking analysis

In this study, black sesame seeds were fermented by Lactobacillus Plantarum NCU116 and then hydrolyzed using acid protease to improve Angiotensin-I-converting enzyme (ACE) inhibitory activity. The random forest-particle swarm optimization (RF-PSO) model was applied to predict the ACE inhibitory activity during the hydrolysis process based on the experimental data. After separating by adsorption chromatography, gel filtration chromatography, and reversed phased-high performance liquid chromatography and then screening in silico method, eight peptides were identified from fermented black sesame seed hydrolysates as ITAPHW, SLPNYHPSPR, QYLPR, IRPNGL, YHNAPIL, LSYPR, GFAGDDAPRA, and LDPNPRSF with IC50 values of 51.69 μM, 146.67 μM, 655.02 μM, 752.60 μM, 1.02 mM, 2.01 mM, 1.97 mM, and 3.43 mM, respectively. ITAPHW and SLPNYHPSPR exhibited high antioxidant activity and inhibited the ACE activity in a non-competitive pattern. Molecular docking revealed that the strong ACE inhibition of ITAPHW and SLPNYHPSPR is probably attributed to the interaction with Zn2+ of ACE.

Identification and In Silico Analysis of ACE-Inhibitory Peptides Derived from Milk Fermented by Lacticaseibacillus paracasei.

Inhibition of angiotensin I-converting enzyme (ACE) activity is an effective way to treat hypertension. In the present study, the ability to produce ACE-inhibitory peptides during fermentation of skimmed milk by the Lacticaseibacillus paracasei M3 strain was evaluated, and the inhibitory mechanism and stability were studied by bioinformatics analysis. The results showed that the ACE inhibition activity of fermented milk was 71.94 ± 1.39%. After digestion with gastric juice and pancreatic juice, the ACE inhibitory activities of the fermented milk were 78.40 ± 1.93 and 74.96 ± 1.73%, respectively. After the fermented milk was purified using ultrafiltration and gel chromatography, 11 peptides from milk proteins were identified and sequenced by Nano LC-MS/MS. Molecular docking displayed that peptide PWIQPK had a high affinity, with ACE showing a binding energy of -6.10 kcal/mol. Hydrogen bonds were formed between PWIQPK and Glu384 in the S1 active pocket of ACE and Asp358. In addition, van der Waals forces were observed. In silico proteolysis suggested that PWIQPK could resist the digestion of pepsin and trypsin, indicating that it is relatively stable in the digestive tract. All results indicate that milk fermented by L. paracasei M3 has the potential to be used as a functional food having antihypertensive effects.

A screening strategy for identifying umami peptides with multiple bioactivities from Stropharia rugosoannulata using in silico approaches and SPR sensing

Umami peptides from natural resources have garnered considerable attention for their potential bioactivities and flavor-enhancing characteristics. In this study, we constructed a database comprising 123 peptides from Stropharia rugosoannulata and screened for umami peptides with both angiotensin I-converting enzyme (ACE) and dipeptidyl peptidase-4 (DPP-IV) inhibitory activities using online prediction tools and molecular docking, and further confirmed by SPR sensing, intelligent sensory and activities test. Five peptides with varying chain lengths were synthesized and by evaluations analyses they exhibited strong umami, with thresholds ranging from 0.105 mmol/L to 0.547 mmol/L. According to the targeted SPR molecular interaction analysis, umami peptides and hT1R3 receptor exhibited a “fast-on/fast-off” binding mode with stronger intensity and persistence than MSG. Furthermore, in vitro experiments revealed that five peptides showed potent ACE and DPP-IV inhibitory activities. Notably, the EAF inhibitory activity was the most significant among the peptides. This comprehensive screening strategy provides a rapid approach for identifying high-sensitivity umami peptides with bioactivities.

Inhibitory effects of the anthocyanins from Lycium ruthenicum Murray on angiotensin-I-converting enzyme: in vitro and molecular docking studies.

Lycium ruthenicum Murray (LRM), a perennial shrub plant belonging to the Solanaceae family, is rich in anthocyanins, which have anti-inflammatory, antioxidant, lipid-lowering, intestinal flora regulating, and other pharmacological qualities. This study was primarily aimed to investigate the inhibitory effect of different anthocyanin purities from LRM on angiotensin-I-converting enzyme (ACE) activity in vitro. Moreover, the inhibitory mechanism was further analyzed by molecular docking technology. Two main anthocyanin isomers were identified by ultra-performance liquid chromatography-tandem mass spectrometry and proton/carbon-13 nuclear magnetic resonance, namely petunidin-3-O-[rhamnopyranosyl-(trans-p-coumaroyl)]-5-O-(β-d-glucopyranoside) (trans-Pt3R5G) and petunidin-3-O-[rhamnopyranosyl-(cis-p-coumaroyl)]-5-O-(β-d-glucopyranoside) (cis-Pt3R5G), with a molar ratio of 9:1. Three purification grades of Pt3R5G all showed excellent inhibitory effects on ACE, with the half maximal inhibitory concentration (IC50 ) values being 0.562, 0.421, and 0.106 mg·mL-1 . Increasing the purity may reduce the IC50 within a certain concentration range. An enzymatic kinetic experiment showed that the inhibitory effect of Pt3R5G on ACE was reversible and non-competitive: Pt3R5G and substrate were not in competition for the active sites of ACE. Molecular docking technology further revealed the possible mechanism was that Pt3R5G and ACE amino acid residues were interacting by hydrogen bonds to exert the inhibitory effect. The results indicated that Pt3R5G from LRM was highly effective at inhibiting ACE activity in vitro, with the hydrogen bonds of Pt3R5G and ACE amino acid residues exerting the inhibition. As a potential plant-based ACE inhibitor, Pt3R5G can be used as a functional ingredient for antihypertensive effects. © 2023 Society of Chemical Industry.

Angiotensin I-Converting Enzyme Inhibitory and Antioxidative Activities of the Bioactive Peptides in the Crude Salt-Soluble Protein Hydrolysates of Pili Nut (Canarium ovatum Engl.) cv. Mayon Kernel

The in silico enzyme digestion and peptide function annotation of pili nut (Canarium ovatum Engl.) 11S globulin protein sequence revealed the presence of bioactive peptides with antihypertensive and antioxidative activities. Molecular docking simulations showed that the proline-histidine (PH) ligand can better inhibit angiotensin I-converting enzyme (ACE) activity than captopril. This result was verified through biochemical assays. Pili kernel protein was extracted with 0.5 M NaCl buffer using the modified Osborne fractionation method, which yielded 100 mg of protein per gram of defatted pili kernel determined via Bradford assay. SDS-PAGE suggested that the protein extract had a major legumin-like (11S) globulin structure with an approximately 57 kDa molecular weight. Enzymatic hydrolysis using pepsin, thermolysin, α-chymotrypsin, and trypsin was used to release the potential antihypertensive and antioxidative peptides with an average rate of 0.03869 mm2 h-1, estimated from band intensity. The hydrolysates were tested for ACE inhibition and free radical scavenging. Captopril and enalapril had %ACE inhibitions of 74.02 and 83.57 %, respectively, whereas the 6 h hydrolysates had a peak %ACE inhibition of 99.73%. These same hydrolysates however, only had 51.32% 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity compared to ascorbic acid, which had 75.59%. These results showed the potential of pili nut as a functional food, especially for preventing high blood pressure and other cardiovascular diseases.

Anchovy’s protein as a potential precursor of Angiotensin-I Converting Enzyme (ACE) inhibitory peptide and Dipeptidyl Peptidase-IV (DPP-IV) inhibitory peptide by an in silico approach

Protein from fish is known as the precursor of biologically active peptides that exert various health benefits such as antihypertensive, antitumor, and immunomodulatory properties. Hence, this study aimed to perform an extraction of anchovy, LC-MS/MS analysis and in silico evaluation of the major proteins in anchovies as potential precursors of biologically active peptides in addition to determining whether such peptides can be released by selected proteolytic enzymes. Anchovy was subjected to protein extraction followed by total soluble protein concentration determination using Bradford assay. The sample was subjected to in-solution trypsin digestion, which was then analysed by liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS). A bioinformatic approach by PEAKS Studio was used to identify the protein. A total of four anchovy’s proteins which are myosin light chain 1, V(D)J recombination-activating protein, 60 kDa chaperonin and heat shock protein 90AA1 were identified. Then, the identified proteins were subjected to in silico approach using the BIOPEP database. The biological potential of the theoretically released angiotensin-I converting enzyme (ACE) inhibitory peptides and dipeptidyl peptidase (DPP)-IV inhibitory peptides were predicted by determining the frequency of occurrence of fragments with a given activity. 60 kDa chaperonin and heat shock protein 90AA1 predicted the highest number of biological activities for ACE inhibitory peptides (284 and 264 fragments) and DPP-IV inhibitory peptides (395 and 409 fragments). The most promising enzyme for the generation of bioactive peptides from anchovy protein was anticipated to be pepsin (pH > 2), which theoretically released a high number of DPP-IV inhibitory peptides and ACE inhibitory peptides through the action of in silico proteolysis. Overall, this work highlighted that anchovy protein could be a promising precursor of bioactive peptides that have ACE and DPP-IV inhibitory activities for developing functional food or nutraceutical products.

Dual antidiabetic and antihypertensive activity of fucoxanthin isolated from Sargassum wightii Greville in in vivo rat model

In a previous study from our laboratory, fucoxanthin purified from brown algae, Sargassum wightii Greville has found to exhibit antioxidant activity and inhibition of angiotensin-I-converting enzyme (ACE) in vitro. The present study aims in understanding the protective effect of fucoxanthin purified from S. wightii against diabetes with hypertension in in vivo. Diabetes and hypertension were induced in rat by streptozotocin and sodium chloride treatment, respectively. In diabetes with hypertension rat, the blood pressure was increased along with hyperglycemia. Administration of fucoxanthin significantly reduced the blood pressure and ACE activity in diabetes with hypertension rat. Furthermore, administration of fucoxanthin significantly reduced the hyperglycemic state. The activity of various enzymes in the liver (hexokinase, glucose-6-phosphate dehydrogenase, glucose-6-phosphatase and fructose-1,6-phosphatase) and serum (creatine kinase) were normalized to that of control level. The level of glycogen, glycoprotein component and lipid profile were equivalent to control level by fucoxanthin administration in diabetes with hypertension rats. Fucoxanthin ameliorated the oxidative stress by preserving the endogenous antioxidant levels in diabetes with hypertension rats. Also, the pancreatic histological integrity was similar to that of control level in diabetes with hypertension rats by fucoxanthin treatment. Altogether, fucoxanthin showed dual antidiabetic and antihypertensive activity in vivo.

Development of lentil peptides with potent antioxidant, antihypertensive, and antidiabetic activities along with umami taste.

Lentil peptides have shown promising bioactive properties regarding the antioxidant activity and also inhibitory activity of angiotensin-I-converting enzyme (ACE). Sequential hydrolysis of proteins has shown a higher degree of hydrolysis with enhanced antioxidant and ACE-inhibitory activities. The lentil protein concentrate (LPC) was sequentially hydrolyzed using Alcalase and Flavourzyme at 2% w/w. The hydrolysate (LPH) was cross-linked (LPHC) or sonicated (LPHUS) and sequentially cross-linked (LPHUSC). Amino acid profile, molecular weight (MW) distribution, DPPH and ABTS radical scavenging activities (RSA; 7mg/mL), ACE (0.1-2mg/mL), α-glucosidase, and α-amylase inhibitory activities (10-500 μg/mL), and umami taste were determined. The highest DPPH RSA was obtained for LPH (68.75%), followed by LPHUSC (67.60%), and LPHUS (67.49%) while the highest ABTS RSA values were obtained for LPHC (97.28%) and LPHUSC (97.20%). Cross-linking and sonication led to the improvement of the ACE-inhibitory activity so that LPHUSC and LPHC had IC50 values of 0.23 and 0.27 mg/mL, respectively. LPHC and LPHUSC also indicated higher α-glucosidase inhibitory activity (IC50 of1.2 and 1.23 mg/mL) compared to LPH (IC50 of1.74 mg/mL) and LPHUS (IC50 of1.75 mg/mL) whilethe IC50 value of acarbose indicated 0.51 mg/mL. Moreover, LPHC and LPHUSC exhibited higher α-amylase inhibitory activities (IC50 of 1.35 and 1.16 mg/mL) than LPHUS (IC50 of 1.95 mg/mL), and LPH (IC50 of 2.51 mg/mL) while acarbose had an IC50 value of 0.43 mg/mL. Umami taste analysis revealed that LPH and LPHC due to MW of 1.7 and 2.3kDa and also high umami amino acids could be well considered as representative of meaty and umami analog flavors while indicating stronger antioxidant, antihypertension, and antidiabetic attributes.

Renal angiotensin I-converting enzyme-deficient mice are protected against aristolochic acid nephropathy

The renal renin-angiotensin system (RAS) is involved in the development of chronic kidney disease. Here, we investigated whether mice with reduced renal angiotensin I-converting enzyme (ACE−/−) are protected against aristolochic acid nephropathy (AAN). To further elucidate potential molecular mechanisms, we assessed the renal abundances of several major RAS components. AAN was induced using aristolochic acid I (AAI). Glomerular filtration rate (GFR) was determined using inulin clearance and renal protein abundances of renin, angiotensinogen, angiotensin I-converting enzyme (ACE) 2, and Mas receptor (Mas) were determined in ACE−/− and C57BL/6J control mice by Western blot analyses. Renal ACE activity was determined using a colorimetric assay and renal angiotensin (Ang) (1–7) concentration was determined by ELISA. GFR was similar in vehicle-treated mice of both strains. AAI decreased GFR in controls but not in ACE−/− mice. Furthermore, AAI decreased renal ACE activity in controls but not in ACE−/− mice. Vehicle-treated ACE−/− mice had significantly higher renal ACE2 and Mas protein abundances than controls. AAI decreased renal ACE2 protein abundance in both strains. Furthermore, AAI increased renal Mas protein abundance, although the latter effect did not reach statistical significance in the ACE−/− mice. Renal Ang(1–7) concentration was similar in vehicle-treated mice of both strains. AAI increased renal Ang(1–7) concentration in the ACE−/− mice but not in the controls. Mice with reduced renal ACE are protected against AAN. Our data suggest that in the face of renal ACE deficiency, AAI may activate the ACE2/Ang(1–7)/Mas axis, which in turn may deploy its reno-protective effects.

Dual Bioactivity of Angiotensin Converting Enzyme Inhibition and Antioxidant Novel Tripeptides from Sipunculus nudus L. and Their Related Mechanism Analysis for Antihypertention

The pathogenesis of hypertension is related to many factors including active angiotensin-I-converting enzyme (ACE) and excess reactive oxygen species (ROS), the combination of ACE inhibition and antioxidant activity in one compound might be useful for the treatment of hypertension. Sipunculus nudus L contain high protein content, which can be used as a valuable raw material to prepare bio-active peptides. In this study, two novel tripeptides, LPK and PRP, with dual bioactivity of ACE inhibition and antioxidant were purified and identified from the worm. The antioxidant activities of LPK and PRP are dose-dependent, including 2,2-diphenyl-1-picrylhydrazyl (DPPH), superoxide anion and hydroxyl radical scavenging activities. Moreover, the antioxidant activity of PRP was stronger than that of LPK. In addition, LPK and PRP also show higher ACE inhibitory activity, with IC50 of 6.54 and 0.42 mM, respectively. Molecular docking simulation showed that both the peptides could interact with the active ACE sites via hydrogen bonds, which can reduce the production of Ang II, thereby; LPK and PRP treatment could decrease Ang II-triggered superoxide production, and meanwhile, the peptides treatment could directly remove excess reactive oxygen species. The above-mentioned advantageous effects appeared to involve the stress of the RAS and scavenging ROS, both were benefit to treat hypertension. This research showed that LPK and PRP had potential to be developed as antihypertension agents, which might be a new strategy for high value utilization of Sipunculus nudus L as functional food material.