Captopril in the treatment of clinical hypertension and cardiac failure

Effective treatment of hypertension by recombinant Lactobacillus plantarum expressing angiotensin converting enzyme inhibitory peptide

Background

Hypertension is considered the most serious risk factor for cardiovascular disease. Angiotensin-converting enzyme inhibitory peptides (ACEIPs), which are made from tuna frame protein (TFP) and yellow fin sole frame protein (YFP), have been used previously to treat hypertension. However, the production of these short peptides is usually dependent on enzymatic hydrolysis, resulting in a digested mixture that makes it difficult to purify the ACEIPs. Although it has been reported that ACEIPs could be produced in recombinant Escherichia coli strains, the use of lactic acid bacteria in the production of ACEIPs has not been demonstrated.

Results

In this study, the ACEIP coding sequences from TFP and YFP were joined through an arginine linker and expressed in the Lactobacillus plantarum (Lb. plantarum) NC8 strain by an inducible vector pSIP-409. Then, the antihypertensive effects were determined in the model of spontaneously hypertensive rats (SHRs) by measuring the blood pressure, hematology, blood biochemistry and nitric oxide (NO), endothelin (ET) and angiotensin II (Ang II) levels. The results showed that oral administration of recombinant Lb. plantarum NC8 (RLP) significantly decreased systolic blood pressure (P < 0.01) during treatment, which lasted for at least 10 days after the last dose. Furthermore, the presence of RLP resulted in an increased level of NO, as well as decreased levels of ET and Ang II in plasma, heart, and kidney. In addition, a dramatically decreased triglyceride level was also observed even though there was no significant change in hematology or blood biochemistry. Although some drawbacks were still observed, such as the presence of an antibiotic selection marker, no obvious side effects or bacterial translocation were observed in vivo, indicating the potential application of RLP in the treatment of hypertension.

Conclusion

These results demonstrated the effectiveness and safety of RLP on the treatment of hypertension.

Marine Peptides: Bioactivities and Applications

Peptides are important bioactive natural products which are present in many marine species. These marine peptides have high potential nutraceutical and medicinal values because of their broad spectra of bioactivities. Their antimicrobial, antiviral, antitumor, antioxidative, cardioprotective (antihypertensive, antiatherosclerotic and anticoagulant), immunomodulatory, analgesic, anxiolytic anti-diabetic, appetite suppressing and neuroprotective activities have attracted the attention of the pharmaceutical industry, which attempts to design them for use in the treatment or prevention of various diseases. Some marine peptides or their derivatives have high commercial values and had reached the pharmaceutical and nutraceutical markets. A large number of them are already in different phases of the clinical and preclinical pipeline. This review highlights the recent research in marine peptides and the trends and prospects for the future, with special emphasis on nutraceutical and pharmaceutical development into marketed products.

Molecular targets of antihypertensive peptides: understanding the mechanisms of action based on the pathophysiology of hypertension

There is growing interest in using functional foods or nutraceuticals for the prevention and treatment of hypertension or high blood pressure. Although numerous preventive and therapeutic pharmacological interventions are available on the market, unfortunately, many patients still suffer from poorly controlled hypertension. Furthermore, most pharmacological drugs, such as inhibitors of angiotensin-I converting enzyme (ACE), are often associated with significant adverse effects. Many bioactive food compounds have been characterized over the past decades that may contribute to the management of hypertension; for example, bioactive peptides derived from various food proteins with antihypertensive properties have gained a great deal of attention. Some of these peptides have exhibited potent in vivo antihypertensive activity in both animal models and human clinical trials. This review provides an overview about the complex pathophysiology of hypertension and demonstrates the potential roles of food derived bioactive peptides as viable interventions targeting specific pathways involved in this disease process. This review offers a comprehensive guide for understanding and utilizing the molecular mechanisms of antihypertensive actions of food protein derived peptides.

Docking Studies of Methylthiomorpholin Phenols (LQM300 Series) with Angiotensin-Converting Enzyme (ACE)

A main target in the treatment of hypertension is the angiotensin-converting enzyme (ACE). This enzyme is responsible for producing angiotensin II, a potent vasoconstrictor. Therefore, one of the targets in the treatment of hypertension is to inhibit ACE activity. Hence, this study's aim is to use computational studies to demonstrate that the proposed heterocyclic compounds have a molecular affinity for ACE and that, furthermore, these heterocyclic compounds are capable of inhibiting ACE activity, thus avoiding the production of the vasopressor Angiotensin II. All this using computer-aided drug design, and studying the systems, with the proposed compounds, through molecular recognition process and compared with the compounds already on the market for hypertension.

LC-MS/MS coupled with QSAR modeling in characterising of angiotensin I-converting enzyme inhibitory peptides from soybean proteins

The importance of soy products in reducing the risk of cardiovascular disease is well documented. Our previous computation study has indicated the presence of several potent ACE inhibitory peptides within soybean proteins which needs to be identified. The aim of the study was to identify ACE inhibitory peptides from soy proteins using LC-MS/MS coupled with quantitative structure-activity relationship (QSAR) model. Soybean protein hydrolysate digested by thermolysin showed an IC50 value of 53.6 μg/mL, decreased slightly to 51.8 μg/mL after adding pepsin, and increased to 115.6 μg/mL after adding trypsin. A total of 34 peptides were characterised from LC-MS/MS. Five novel tripeptides, IVF, LLF, LNF, LSW and LEF, with predicted IC50 values lower than 10 μM were synthesized and validated. The results showed that soybean is an excellent source of ACE inhibitory peptides.

Egg-derived tri-peptide IRW exerts antihypertensive effects in spontaneously hypertensive rats

Background

There is a growing interest in using functional food components as therapy for cardiovascular diseases such as hypertension. We have previously characterized a tri-peptide IRW (Ile-Arg-Trp) from egg white protein ovotransferrin; this peptide showed anti-inflammatory, anti-oxidant and angiotensin converting enzyme (ACE) inhibitor properties invitro. Given the pathogenic roles played by angiotensin, oxidative stress and inflammation in the spontaneously hypertensive rat (SHR), we tested the therapeutic potential of IRW in this well-established model of hypertension.

Methods and Results

16–17 week old male SHRs were orally administered IRW at either a low dose (3 mg/Kg BW) or a high dose (15 mg/Kg BW) daily for 18 days. Blood pressure (BP) and heart rate were measured by telemetry. Animals were sacrificed at the end of the treatment for vascular function studies and measuring markers of inflammation. IRW treatment attenuated mean BP by ~10 mmHg and ~40 mmHg at the low- and high-dose groups respectively compared to untreated SHRs. Heart rate was not affected. Reduction in BP was accompanied by the restoration of diurnal variations in BP, preservation of nitric oxide dependent vasorelaxation, as well as reduction of plasma angiotensin II, other inflammatory markers and tissue fibrosis.

Conclusion

Our results demonstrate anti-hypertensive effects of IRW invivo likely mediated through ACE inhibition, endothelial nitric oxide synthase and anti-inflammatory properties.

Comparison of analytical methods to assay inhibitors of angiotensin I-converting enzyme

The linearity, precision and repeatability of visible spectrophotometric (VSP) and high-performance liquid chromatography (HPLC) methods for analysis of inhibitory activity of angiotensin I-converting enzyme (ACE) were compared by using several inhibitors and Hip-His-Leu (HHL) as substrates. IC50 values (concentration at which ACE activity is inhibited by 50%) of 0.00206±0.00005 μg/mL for captopril, 192±4.53 μg/mL for soybean peptides, and 153±4.29 μg/mL for grass carp peptides determined by the VSP method, and these values were 1.07, 1.07, 1.18 and 1.44-fold, respectively, higher than those from the HPLC method. In addition, the inhibitory constant (Ki value) of captopril was determined to be 7.09 nM and 4.94 nM using VSP and HPLC method, respectively. These results showed that the HPLC method revealed a higher level of sensitivity and precision, suitable for assaying ACE inhibition activity of antihyper-sensitive peptides. In contrast, the VSP method can simultaneously measure several samples with simple operations, suitable for analysis of ACE inhibition activity of food protein enzymatic hydrolysates.

Purification and identification of an ACE inhibitory peptide from walnut protein

In the present study, a novel angiotensin I-converting enzyme (ACE)-inhibitory peptide, P-2a2, was purified to homogeneity from walnut protein hydrolysate by ultrafiltration, consecutive column chromatography, and high-performance liquid chromatography. The purified peptide was characterized by matrix-assisted laser desorption ionization time-of-flight mass spectrophotometry and a liquid-phase peptide sequencer. The molecular mass of P-2a2 was tested to be 1033.42 D. Its amino acid sequence was determined to be Trp-Pro-Glu-Arg-Pro-Pro-Gln-Ile-Pro. The potent ACE-inhibitory peptide is an enneapeptide and shows a high ACE-inhibitory activity, with an IC50 value of 25.67 μg/mL.

WITHDRAWN: Bioactive peptides derived from meat proteins

This article has been withdrawn at the request of the Editor. The Publisher apologizes for any inconvenience this may cause. The full Elsevier Policy on Article Withdrawal can be found at http://www.elsevier.com/locate/withdrawalpolicy.

Antihypertensive activity of recombinant peptide IYPR expressed in Escherichia coli as inclusion bodies

To produce more angiotensin converting enzyme inhibitory peptides (ACEIP), we have established a high-efficiency Escherichia coli expression system. The DNA-coding sequence for the recombinant protein, which was subcloned into the vector pET-30a(+), has been expressed as inclusion bodies in E. coli BL21 (DE3). The influences of induction time and concentration of isopropyl-β-D-thiogalactopyranoside (IPTG) on the expression of recombinant protein were studied. The resulting expression level of the protein accounted for about 31% of cellular protein at a temperature of 37°C, IPTG concentration of 0.6mM and induction time of 7h. The inclusion bodies were washed, separated from the cells, and solubilized with urea. After purification by affinity chromatography, the recombinant protein was recovered with a high purity of about 90%. Molecular weight of the recombinant protein was measured using Tricine-SDS-PAGE. Peptide IYPR was obtained by cleavage of the recombinant protein with trypsin and the IC(50) value was 61 mg/L. The antihypertensive activity in spontaneously hypertensive rats (SHRs) was also investigated. Single oral administration of this peptide in 10-week old SHRs resulted in a significant reduction of systolic blood pressure to 50 mm Hg at 4 h. The data obtained provide a good reference for further development of peptide Ile-Tyr-Pro-Arg into an effective antihypertensive agent for prevention and treatment of hypertension.

Development of a reversed-phase high-performance liquid chromatography analytical methodology for the determination of antihypertensive peptides in maize crops

The aim of this work was to estimate the content of three highly antihypertensive peptides (LQP, LSP, and LRP) in different maize crops. For that purpose, a method consisting of the extraction of the protein containing these peptides (α-zeins), releasing of peptides by thermolysin digestion, and separation and detection of peptides was designed. The rapid and efficient ultrasound assisted extraction of α-zeins proteins from whole maize kernels was achieved using 70% of ethanol followed by precipitation with acetone. A 10 mM Tris-HCl (pH 8.0) buffer containing 8M urea enabled to dissolve the precipitated α-zeins. This buffer was diluted to reach a 6 M urea concentration before digestion to keep active the enzyme. Other digestion parameters that were optimized were: enzyme to substrate ratio (5:100 was selected), digestion temperature (50°C) and digestion time (6 h). The RP-HPLC separation in a fused-core column was also optimized allowing the separation of the three peptides extracted from maize kernels in 6 min. The presence of the three antihypertensive peptides in the digested extract was confirmed using HPLC-Q-TOF-MS analysis and by comparison with peptide standards. Clear differences were observed in the content of the three antihypertensive peptides and, thus, in the antihypertensive activity of the analyzed crops. The content of LRP peptide was very low regardless of the maize variety while the content of LQP and LSP significantly varied among studied maize lines.

Kinetics of the inhibition of renin and angiotensin i converting enzyme by polar and non-polar polyphenolic extracts of Vernonia amygdalina and Gongronema latifolium leaves

The aim of this study was to determine the in vitro modulation of the renin-angiotensin system by polyphenolic extracts and fractions of two green leafy vegetables, Vernonia amygdalina (VA) and Gongronema latifolium (GL), that are used for food and medicinal purposes. An 80% acetone extract of each leaf was fractionated on silicic acid-packed column to give two main fractions: acetone eluate (flow-through) and ethanol eluate (column-bound), that consist mostly of chlorophyllic and non-chlorophyllic fractions, respectively. Column fractionation resulted in polyphenolic fractions that displayed higher potency against angiotensin converting enzyme (ACE) and renin than the crude acetone extracts; generally, the chlorophyllic fraction was more active than the non-chlorophyllic fraction. ACE-inhibitory activity was significantly higher (p < 0.05) for the chlorophyllic fraction of VA than GL, with IC(50) values of 0.207 and 0.413 mg/ml, respectively. Similarly, the chlorophyllic fraction of VA had significantly higher (p < 0.05) renin inhibition than GL, with IC(50) values of 0.172 and 0.513 mg/ml, respectively. Kinetics studies showed that the chlorophyllic fractions of VA and GL exhibited mostly mixed-type ACE and renin inhibitions. We concluded that the hydrophobic nature of the chlorophyllic fraction may have contributed to the increased interaction with enzyme protein and inhibition of activities of ACE and renin.

Potential pharmacological applications of polyphenolic derivatives from marine brown algae

Recently, the isolation and characterization of the biologically active components from seaweeds have gained much attention from various research groups across the world. The marine algae have been studied for biologically active components and phlorotannins are one among them. Among marine algae, brown algal species such as Ecklonia cava, Eisenia arborea, Ecklonia stolinifera and Eisenia bicyclis have been studied for their potential biological activities. Majority of the investigations on phlorotannins derived from brown algae have exhibited their potentiality as antioxidant, anti-inflammatory, antidiabetic, antitumor, antihypertensive, anti-allergic, hyaluronidase enzyme inhibition and in matrix metalloproteinases (MMPs) inhibition activity. In this review, we have made an attempt to discuss the potential biological activities of phlorotannins from marine brown algae and their possible candidature in the pharmaceutical applications.

The evolution of angiotensin blockade in the management of cardiovascular disease

Dysregulation of the renin-angiotensin system is implicated in many cardiovascular and renal pathologies. Discovery of the renin-angiotensin system represents a major advance in the understanding of hypertension and cardiovascular disease, leading to the development of the anti-angiotensin medications: angiotensin-converting enzyme inhibitors, angiotensin receptor blockers and direct renin inhibitors. Clinical trials have shown that drugs in each of these classes have a protective effect on vascular organs that surpass the protection associated with the lowering of blood pressure alone.