ACE inhibition in hypertension: focus on perindopril

Inhibitory activities of grape bioactive compounds against enzymes linked with human diseases

A quest for identification of novel, safe and efficient natural compounds, as additives in the modern food and cosmetic industries, has been prompted by concerns about toxicity and side effects of synthetic products. Plant phenolic compounds are one of the most documented natural products due to their multifarious biological applications. Grape (Vitis vinifera) is an important source of phenolic compounds such as phenolic acids, tannins, quinones, coumarins and, most importantly, flavonoids/flavones. This review crisply encapsulates enzyme inhibitory activities of various grape polyphenols towards different key human-ailment-associated enzymes: xanthine oxidase (gout), tyrosinase (hyperpigmentation), α-amylase and α-glucosidase (diabetes mellitus), pancreatic lipase (obesity), cholinesterase (Alzheimer's disease), angiotensin i-converting enzymes (hypertension), α-synuclein (Parkinson's disease) and histone deacetylase (various diseases). The review also depicts the enzyme inhibitory mechanism of various grape polyphenols and briefly discusses their stature as potential therapeutic and drug development candidates. KEY POINTS: • Nineteen major bioactive polyphenols from the grape/grape products and their disease targets are presented • Sixty-two important polyphenols as enzyme inhibitors from grape/grape products are presented • A thorough description and graphical presentation of biological significance of polyphenols against various diseases.

A Proline-Based Tectons and Supramolecular Synthons for Drug Design 2.0: A Case Study of ACEI

Proline is a unique, endogenous amino acid, prevalent in proteins and essential for living organisms. It is appreciated as a tecton for the rational design of new bio-active substances. Herein, we present a short overview of the subject. We analyzed 2366 proline-derived structures deposited in the Cambridge Structure Database, with emphasis on the angiotensin-converting enzyme inhibitors. The latter are the first-line antihypertensive and cardiological drugs. Their side effects prompt a search for improved pharmaceuticals. Characterization of tectons (molecular building blocks) and the resulting supramolecular synthons (patterns of intermolecular interactions) involving proline derivatives, as presented in this study, may be useful for in silico molecular docking and macromolecular modeling studies. The DFT, Hirshfeld surface and energy framework methods gave considerable insight into the nature of close inter-contacts and supramolecular topology. Substituents of proline entity are important for the formation and cooperation of synthons. Tectonic subunits contain proline moieties characterized by diverse ionization states: -N and -COOH(-COO-), -N+ and -COOH(-COO-), -NH and -COOH(-COO-), -NH+ and -COOH(-COO-), and -NH2+ and -COOH(-COO-). Furthermore, pharmacological profiles of ACE inhibitors and their impurities were determined via an in silico approach. The above data were used to develop comprehensive classification, which may be useful in further drug design studies.

Role of the NO/cGMP pathway and renin-angiotensin system in the hypotensive and diuretic effects of aqueous soluble fraction from Crataegus songarica K. Koch

ETHNO-PHARMACOLOGICAL RELEVANCE

Fruits of Crataegus songarica K. Koch. (Rosaceae) are commonly used in folk medicine for their diuretic properties to treat hypertension and congestive heart failure. To date, no scientific data has been published to support the diuretic potential.

AIM OF THE STUDY

The purpose of this study was to evaluate efficacy and mechanism underlying the hypotensive and diuretic action of C. songarica in normotensive rats and to determine the constituents from the extracts by LC-DAD-MS.

MATERIALS AND METHODS

Firstly, phytochemical profiling and antioxidant potential of C. songarica extracts was determined. Then, to evaluate changes in blood pressure, different groups of anesthetized normotensive rats were intravenously treated with crude extract (CS-Cr, 10-80 mg/kg), aqueous soluble (AS-CS, 0.1-20 mg/kg), and n-butanol soluble fractions of C. songarica (BS-CS, 1-80 mg/kg). The diuretic effects of CS-Cr (100-500 mg/kg, p.o), AS-CS (100-300 mg/kg, p.o) and BS-CS (100-300 mg/kg, p.o) were evaluated in comparison with hydrochlorothiazide (HCTZ, 10 mg/kg, p.o). The urinary volume, sodium, potassium and pH were estimated in the sample collected for 6 h from saline-loaded rats. Using pharmacological antagonists or inhibitors, we determine the involvement of acetylcholine, prostaglandins, and nitric oxide in C. songarica induced hypotensive and diuresis action. In addition, the activities of angiotensin converting enzyme, erythrocytary carbonic anhydrase and renal Na+/K+/ATPase were evaluated in vitro.

RESULTS

From the LC-DAD-MS analyses, thirty-nine compounds were detected, showing a complex chemical profile and an expressive antioxidant activity "in vitro". Acute treatment with CS-Cr, AS-CS, and BS-CS exhibited significant hypotensive and diuretic potential in normotensive rats. However, AS-CS produced most potent and significant dose-dependent hypotension in normotensive rats, and also produced highly significant diuretic and saluretic effects. Despite the changes in urinary excretion of electrolytes, the plasmatic levels of sodium and potassium were not changed. Previous treatment with atropine and L-NAME significantly reduced the hypotensive and diuretic action of AS-CS in normotensive rats. Moreover, the 7-day treatment with AS-CS also resulted in significant ACE inhibitory activity.

CONCLUSION

This research supports and extends the ethnomedicinal use of C. songarica as diuretic and hypotensive agent. The results showed that AS-CS from C. songarica could present compounds responsible for hypotensive and diuretic activities with no signs of toxicity, and these effects could involve nitric oxide pathway activated by muscarinic receptors or/and inhibition of angiotensin converting enzyme.

Heterologous expression, purification, and functional characterization of recombinant ovine angiotensinogen in the methylotrophic yeast Pichia pastoris

Angiotensinogen (AGT), a glycosylated plasma noninhibitory serpin, serves as a precursor for angiotensin peptides which regulate blood pressure and electrolyte balance. AGT is specifically cleaved by renin to produce angiotensin-I, the first product of the angiotensin-processing cascade. Ovine angiotensinogen (oAGT) is considered an effective substrate for human renin and consequently finds application in clinical renin assays. In this study, oAGT was cloned into the genome of Pichia pastoris and expressed under the control of alcohol oxidase (AOX1) promoter for high-level production. Compared to the shake flask study, the high cell density cultivation in bioreactor resulted in multifold increase in oAGT titer (420 ± 9.26 mg/L), which is its highest reported titer to date. We purified recombinant oAGT to homogeneity using two chromatography steps. The characterization studies revealed oAGT underwent a two-state transition during thermal denaturation process as assessed by differential scanning fluorimetry, and the melting temperature (T_m ) of the purified oAGT from P. pastoris was 48.3°C. Renin reactivity with recombinant oAGT from P. pastoris (0.51 nM angiotensin-I/min) was slightly lower than the renin reactivity for recombinant oAGT from Escherichia coli (0.67 nM angiotensin-I/min), possibly because of its mannosylated N-glycan content. Enhanced production of functionally active recombinant oAGT using P. pastoris expression system reported in this study envisage the effective utilization of oAGT in clinical studies related to renin in near future.

Perindopril Induces TSP-1 Expression in Hypertensive Patients with Endothelial Dysfunction in Chronic Treatment

Thrombospondin-1 (TSP-1) is a potent endogenous inhibitor of both physiological and pathological angiogenesis, widely studied as a target in drug development for treating cancer. Several studies performed in the cardiovascular field on TSP-1 are contradictory, the role of TSP-1 in the physiopathology of cardiovascular disorders (CVDs) being, for the moment, incompletely understood and may be due to the presence of several domains in its structure which can stimulate many cellular receptors. It has been reported to inhibit NO-mediated signaling and to act on the angiogenesis, tissue perfusion, endothelial cell proliferation, and homeostasis, so we aimed to quantify the effect Perindopril has on TSP-1 plasma levels in hypertensive patients with endothelial dysfunction in comparison with other antihypertensive drugs, such as beta blockers, calcium channel blockers, and diuretics, in a chronic treatment. As a conclusion, patients under treatment with Perindopril had increased plasma levels of TSP-1 compared with other hypertensive patients and with the control group. The results of this study confirms the pleiotropic properties of Perindopril: anti-proliferative, anti-inflammatory, with effects showed by quantifying a single biomarker: TSP-1.

Comparative Solid-State Stability of Perindopril Active Substance vs. Pharmaceutical Formulation

This paper presents the results obtained after studying the thermal stability and decomposition kinetics of perindopril erbumine as a pure active pharmaceutical ingredient as well as a solid pharmaceutical formulation containing the same active pharmaceutical ingredient (API). Since no data were found in the literature regarding the spectroscopic description, thermal behavior, or decomposition kinetics of perindopril, our goal was the evaluation of the compatibility of this antihypertensive agent with the excipients in the tablet under ambient conditions and to study the effect of thermal treatment on the stability of perindopril erbumine. ATR-FTIR (Attenuated Total Reflectance Fourier Transform Infrared) spectroscopy, thermal analysis (thermogravimetric mass curve (TG-thermogravimetry), derivative thermogravimetric mass curve (DTG), and heat flow (HF)) and model-free kinetics were chosen as investigational tools. Since thermal behavior is a simplistic approach in evaluating the thermal stability of pharmaceuticals, in-depth kinetic studies were carried out by classical kinetic methods (Kissinger and ASTM E698) and later with the isoconversional methods of Friedman, Kissinger-Akahira-Sunose and Flynn-Wall-Ozawa. It was shown that the main thermal degradation step of perindopril erbumine is characterized by activation energy between 59 and 69 kJ/mol (depending on the method used), while for the tablet, the values were around 170 kJ/mol. The used excipients (anhydrous colloidal silica, microcrystalline cellulose, lactose, and magnesium stearate) should be used in newly-developed generic solid pharmaceutical formulations, since they contribute to an increased thermal stability of perindopril erbumine.

Combinations of inhibitors of the renin-angiotensin system with calcium channel blockers for the treatment of hypertension: focus on perindopril/amlodipine

BACKGROUND

Combination antihypertensive therapy with an inhibitor of the renin-angiotensin system (RAS) and a calcium channel blocker (CCB) is a rational approach to achieve blood pressure (BP) goals in patients with hypertension, and may provide additional cardiovascular protection compared to other strategies in special populations. This article reviews the rationale for, and evidence supporting, the use of newer fixed-dose combinations of RAS inhibitors and CCBs, with particular emphasis on perindopril/amlodipine.

METHODS

A literature search was performed in Medline and EMBASE databases to identify articles published up to May 2010 describing the impact of combination treatment with angiotensin receptor blocker (ARB)/CCB or angiotensin-converting enzyme (ACE) inhibitor/CCB based antihypertensive strategies on BP or clinical outcomes.

FINDINGS

A substantial body of evidence supports the BP-lowering efficacy of RAS inhibitor/CCB combination therapy in patients with hypertension. RAS inhibitors and CCBs represent two different and complementary mechanisms of actions; their use in combination is associated with effective BP lowering with favourable tolerability and fewer adverse metabolic effects than some other combination therapies. Currently, intervention studies demonstrating the impact of ARB/CCB combinations on cardiovascular mortality and morbidity are lacking. However, evidence from large outcome trials supports the use of ACE inhibitor/CCB combinations for reducing the risk of cardiovascular and renal events, particularly in high-risk patients. There is also evidence that the benefits of ACE inhibitor/CCB combinations may extend beyond those solely associated with brachial BP lowering, by an additional impact on central BP haemodynamics.

CONCLUSIONS

RAS inhibitor/CCB combination therapy is an effective antihypertensive therapy. Strong evidence supports the antihypertensive efficacy of ACE inhibitor/CCB combinations with cardioprotective and renoprotective properties. In particular, evidence suggests that fixed-dose perindopril/amlodipine effectively decreases BP and currently is the only RAS inhibitor/CCB combination proven to decrease all-cause and cardiovascular mortality as well as major cardiovascular events, and thus is a valuable option for the management of hypertension, especially in high-risk patients.

Applied Healthspan engineering

According to the Homeric Hymn to Aphrodite, when Eos asked Zeus for Tithonus to be granted immortality, she forgot to ask for eternal youth. Applied Healthspan Engineering (AHE) seeks to address this problem. All organisms have a minimal level of functional reserve required to sustain life that eventually declines to a point incompatible with survival at death. AHE seeks to maintain or restore optimal functional reserve of critical tissues and organs. Tissue reserve correlates with well being. Diet, physical exercise, and currently available small-molecule-based therapeutics may attenuate the rate of decline of specific organs or organ systems, but are unlikely to restore lost reserve. Inherent evolutionary-derived limitations in tissue homeostasis and cell maintenance necessitate the development of therapies to enhance regenerative processes and possibly replace whole organs or tissues. AHE supports the study of cell, tissue, and organ homeostatic mechanisms to derive new regenerative and tissue replacement therapies to extend the period of human health.

Benefits of the RAS blockade: clinical evidence before the ONTARGET study

Activation of the AT1 angiotensin II (Ang II) receptors has various effects including vasoconstriction, hypertrophy, and possibly hyperplasia of vascular smooth muscle cells and cardiomyocytes and increase in extracellular collagen matrix synthesis. These actions lead to the development of cardiovascular hypertrophy and fibrosis, as well as arterial stiffness, which are some key factors in the development of the cardiovascular and renal complications. In clinical studies, it has been shown that renin-angiotensin blockade has direct and specific implications in the evolution of heart failure, coronary disease, stroke, and hypertensive and diabetic renal disease. The beneficial cardiovascular and renal effects of blocking the renin-angiotensin-aldosterone system reported in numerous clinical trials may be at least partially related to the actions of these drugs on cardiovascular and renal fibrosis, and arterial stiffness. These effects are now well-established and lead the international medical societies to propose the use of the renin-angiotensin system (RAS) blockers as initial treatment (both angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers) in several cardiovascular, metabolic, and renal disorders such as hypertension, heart failure, and proteinuria.

Secondary prevention after acute myocardial infarction and coronary revascularisation: focus on Angiotensin converting enzyme inhibitors

INTRODUCTION

Cardiovascular disease (CVD) is responsible for an estimated one third of all deaths worldwide.

PATIENTS AND METHODS

One group of patients who are at a particularly high risk of cardiovascular events and death are those with stable coronary artery disease (CAD), especially if they have had a previous myocardial infarction (MI) or revascularisation.

DISCUSSION

Lifestyle changes (smoking, alcohol intake, diet, exercise) and cardiac rehabilitation play an important part in reducing risk of recurrent events. In patients with a history of MI and/or those who underwent myocardial revascularisation these have to be supplemented with medication. Several pharmacological agents are known to improve prognosis in these patients, i.e. beta-blockers, antiplatelet agents, statins, and angiotensin converting enzyme inhibitors (ACEi). The present article focuses mainly on the role of ACEi in the prevention of cardiovascular events in patients with a history of MI or myocardial revascularization.