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Flavonoids have various pharmacological activities, such as antihypertensive, anticancer, and and antidiabetic effects. Several studies have shown that luteolin, quercetin, kaempferol, myricetin, naringenin, hesperetin, and epicatechin have antihypertensive effects, but the mechanism of action has yet to be discovered with certainty. This study aims to identify flavonoids from luteolin, quercetin, kaempferol, myricetin, naringenin, hesperetin, and epicatechin as renin inhibitors through in silico study; seven flavonoid compounds were docked with 2V0Z with renin inhibitor (Aliskiren) in humans (Homo sapiens 6 LU7) using AutoDock v4.2.6. SwissADME was used to evaluate the pharmacokinetic characteristics of these substances. Results molecular binding of luteolin, quercetin, kaempferol, myricetin, naringenin, hesperetin, and epicatechin, has potential as renin inhibitors with affinity energy values lower than those of aliskiren of −9.3; −9.3; −10.0; −9.2; −9.9; −9.3; and −9.7 kcal/mol. The interactions of these seven compounds have the same catalytic activity as aliskiren on two aspartic acid residues, Asp32 and Asp215. The analysis of pharmacokinetic profiles and the search for physical and chemical properties showed that the seven compounds violated three of the five Lipinski rules, while aliskiren violated one. Hesperitin, kaempferol, and naringenin had similarities with aliskiren on the amino-acid residues in the renin-binding pocket. However, based on pharmacokinetic analysis, the three compounds had an oral pharmacokinetic profile that could have been better than aliskiren.

Flavonoids have various pharmacological activities, such as antihypertensive, anticancer, and and antidiabetic effects. Several studies have shown that luteolin, quercetin, kaempferol, myricetin, naringenin, hesperetin, and epicatechin have antihypertensive effects, but the mechanism of action has yet to be discovered with certainty. This study aims to identify flavonoids from luteolin, quercetin, kaempferol, myricetin, naringenin, hesperetin, and epicatechin as renin inhibitors through in silico study; seven flavonoid compounds were docked with 2V0Z with renin inhibitor (Aliskiren) in humans (Homo sapiens 6 LU7) using AutoDock v4.2.6. SwissADME was used to evaluate the pharmacokinetic characteristics of these substances. Results molecular binding of luteolin, quercetin, kaempferol, myricetin, naringenin, hesperetin, and epicatechin, has potential as renin inhibitors with affinity energy values lower than those of aliskiren of -9.3; -9.3; -10.0; -9.2; -9.9; -9.3; and -9.7 kcal/mol. The interactions of these seven compounds have the same catalytic activity as aliskiren on two aspartic acid residues, Asp32 and Asp215. The analysis of pharmacokinetic profiles and the search for physical and chemical properties showed that the seven compounds violated three of the five Lipinski rules, while aliskiren violated one. Hesperitin, kaempferol, and naringenin had similarities with aliskiren on the amino-acid residues in the renin-binding pocket. However, based on pharmacokinetic analysis, the three compounds had an oral pharmacokinetic profile that could have been better than aliskiren. [ABSTRACT FROM AUTHOR]

Hypertension is a silent killer that causes kidney, heart, and stroke damage if not handled properly. In Indonesia, the prevalence of the population with high blood pressure is 34.11% with women 36.85% higher than men 31.34%, this shows a fairly high value so that special attention is needed on hypertension therapy. It is known that currently there are 6 types of pharmacological therapy for hypertension and one of the newest is the renin inhibitor class (Aliskiren). Indonesia has diverse natural wealth in the form of flora and fauna, with a wealth of more than 30,000 types of medicinal plants with 9500 potential herbal medicines that have not been utilized optimally, with the largest exporter of herbal medicines in the world. Centella asiatica plants containing triterpenoid saponins have high renin inhibitor activity, namely the content of Asiaticoside and Madecasoside. The research method was carried out in silico using molecular simulation and in vitro with fluorometry (328/552 nm) to test the activity of asiaticoside and madecasoside compounds as well as a mixture of asiaticoside and madecasoside in Centella asiatica plants. This is supported by the docking outcome. The docking results show that madecososide compounds have a gibbs energy close to the positive control aleskiren (-8.356 kcal/mol) and aleskiren (-9.44 kcal/mol). The experiment results showed that the triterpenoid saponin compound (madecassoside) contained an IC value of 0.71, at a concentration of 5 µg/µl, and absorbance of 1.35 A in the first minute. The strongest renin inhibition was Madecasoside compound with a concentration of 5 µg/µl with an average value of fluorescent adsorption and an average percent inhibition of 135% with the best renin inhibition at Madecasoside 5 ug/ul the first minute with absorbance values 1.19 A. Finally, the in silico result corresponded to the in vitro experiment. Centella asiatica plants have renin inhibitor activity as antihypertensive, especially in secondary metabolites of triterpene saponins with pure madecasoside compounds compared with aliskiren as a renin inhibitor. So that the compound madecasoside has renin inhibitor activity as an antihypertensive. [ABSTRACT FROM AUTHOR]

Depression is considered a neuropsychic disease that has global prevalence and is associated with disability. The pathophysiology of depression is not well understood; however, emerging evidence has indicated that neuroinflammation could contribute to developing depression symptoms. One of the factors that have a role in the development of neuroinflammation is the renin–angiotensin system. Therefore, the goal of the current study is to determine the antidepressant-like effects of Aliskiren, a renin inhibitor, against lipopolysaccharide (LPS)-induced depressive-like behavior in mice, glial cell activation, and the upregulation of proinflammatory cytokines in the prefrontal cortex. For behavioral studies, the open field test (OFT), tail suspension test (TST), forced swim test (FST), and sucrose preference test (SPT) were used. Inflammatory markers were assessed using real-time polymerase chain reaction (RT-PCR). LPS administration (0.5 mg/kg, intraperitoneal injection (i.p.)) sufficiently reduced the number of crossings in OFT, whereas Aliskiren pretreatment (10 mg/kg, i.p.) attenuated the LPS effect for two hours after LPS injection. The treatments did not show effects on locomotor activity in OFT 24 h after LPS administration. LPS increased the immobility time in TST and FST or reduced sucrose consumption in SPT after 24 h. Aliskiren reversed the effects induced by LPS in TST, FST, and SPT. CD11 b mRNA, a microglial marker, GFAP mRNA, an astroglial marker, and proinflammatory cytokines genes (TNF-α, IL-1β, and IL-6) were upregulated in the prefrontal cortex in LPS exposed animals. However, Aliskiren reduced LPS-induced inflammatory genes in the prefrontal cortex. Hence, the outcomes conclude that Aliskiren prevents depressive illness associated with neuroinflammation in humans. [ABSTRACT FROM AUTHOR]

The increasing use of pharmaceuticals, their presence in the aquatic environment, and the associated toxic effects, have raised concerns in recent years. In this work, a new multi-residue analytical method was developed and validated for the determination of 10 pharmaceuticals in wastewaters using online solid-phase extraction (online SPE) and liquid chromatography-tandem mass spectrometry (LC-MS/MS). The compounds included in the method were antineoplastics (cabazitaxel, docetaxel, doxorubicin, etoposide, irinotecan, methotrexate, paclitaxel, and topotecan), renin inhibitors (aliskiren), and antidepressants (maprotiline). The method was developed through several experiments on four online SPE cartridges, three reversed phase chromatography columns, and four combinations of mobile phase components. Under optimal conditions, very low limits of detection (LODs) of 1.30 to 10.6 ng L−1 were obtained. The method was repeatable, with relative standard deviations (RSD, %) for intraday and interday precisions ranged from 1.6 to 7.8 and from 3.3 to 13.2, respectively. Recovery values ranged from 78.4 to 111.4%, indicating the reproducibility of the method. Matrix effects were mainly presented as signal suppression, with topotecan and doxorubicin being the two most affected compounds (31.0% signal suppression). The proposed method was successfully applied to hospital effluents, detecting methotrexate (4.7–9.3 ng L−1) and maprotiline (11.2–23.1 ng L−1). Due to the shorter overall run time of 15 min, including sample preparation, and reduced sample volume (0.9 mL), this on-line SPE-LC-MS/MS method was extremely convenient and efficient in comparison to the classical off-line SPE method. The proposed method was also highly sensitive and can be used for ultratrace quantification of the studied pharmaceuticals in wastewaters, providing useful data for effective environmental monitoring. [ABSTRACT FROM AUTHOR]

Renin is the rate‐limiting enzyme of the renin–angiotensin system cascade, which drives the pathophysiological progression of heart failure. Species differences in the amino acid sequence of the catalytic domain of renin limit evaluations of the potency and efficacy of human renin inhibitors in animal models, and a high dose of inhibitors is usually needed to show its organ‐protective effects in rodents. In the present study, we developed a novel murine heart failure model (triple‐tg) to enable us to evaluate the cardioprotective effect of renin inhibitors at more relevant doses for humans, by cross‐breeding calsequestrin transgenic (CSQ‐tg) mice with human renin and human angiotensinogen double‐transgenic mice. The triple‐tg mice exhibited increased plasma renin activity, worsened cardiac hypertrophy, and higher mortality compared to CSQ‐tg mice. Triple‐tg mice treated with 10 mg·kg−1 of TAK‐272 (imarikiren/SCO‐272), an orally active direct renin inhibitor, exhibited improvements in heart failure phenotypes, such as cardiac hypertrophy and survival rate; however, a dose of 300 mg·kg−1 was required to improve symptoms in CSQ‐tg mice. Our results suggest that this newly generated triple‐tg heart failure model is useful to evaluate the cardioprotective effects of human renin inhibitors at clinically relevant doses, thereby minimizing the concerns of off‐target effects related to much higher drug exposure than that achieved in clinical study.

Background The potential long-term safety and efficacy of aliskiren in nondiabetic chronic kidney disease (CKD) are unknown. We sought to investigate the renoprotective effect of aliskiren on nondiabetic CKD patients. Methods In this open-label, parallel, randomized controlled trial, nondiabetic CKD Stages 3–4 patients were randomized to receive aliskiren added to an angiotensin II receptor blocker (ARB) at the maximal tolerated dose, or ARB alone. Primary outcome was the rate of change in estimated glomerular filtration rate (eGFR). Secondary endpoints included rate of change in urine protein-to-creatinine ratio (UPCR), cardiovascular events and hyperkalemia. Composite renal outcomes of doubling of baseline serum creatinine or a 40% reduction in eGFR or incident end-stage renal disease or death were analyzed as post hoc analysis. Results Seventy-six patients were randomized: 37 to aliskiren (mean age 55.1 ± 11.1 years) and 39 to control (mean age 55.0 ± 9.4 years). Their baseline demographics were comparable to eGFR (31.9 ± 9.0 versus 27.7 ± 9.0 mL/min/1.73 m2, P  =  0.05) and UPCR (30.7 ± 12.6 versus 47.8 ± 2.8 mg/mmol, P  =  0.33) for treatment versus control subjects. After 144 weeks of follow-up, there was no difference in the rate of eGFR change between groups. Six patients in the aliskiren group and seven in the control group reached the renal composite endpoint (16.2% versus 17.9%, P  =  0.84). The cardiovascular event rate was 10.8% versus 2.6% (P  =  0.217). The hyperkalemia rate was 18.9% versus 5.1% with an adjusted hazard ratio of 7.71 (95% confidence interval 1.14 to 52.3, P  =  0.04) for the aliskiren arm. Conclusion Aliskiren neither conferred additional renoprotective benefit nor increased adverse events, except for more hyperkalemia in nondiabetic CKD patients. [ABSTRACT FROM AUTHOR]

Depression is considered a neuropsychic disease that has global prevalence and is associated with disability. The pathophysiology of depression is not well understood; however, emerging evidence has indicated that neuroinflammation could contribute to developing depression symptoms. One of the factors that have a role in the development of neuroinflammation is the renin–angiotensin system. Therefore, the goal of the current study is to determine the antidepressant-like effects of Aliskiren, a renin inhibitor, against lipopolysaccharide (LPS)-induced depressive-like behavior in mice, glial cell activation, and the upregulation of proinflammatory cytokines in the prefrontal cortex. For behavioral studies, the open field test (OFT), tail suspension test (TST), forced swim test (FST), and sucrose preference test (SPT) were used. Inflammatory markers were assessed using real-time polymerase chain reaction (RT-PCR). LPS administration (0.5 mg/kg, intraperitoneal injection (i.p.)) sufficiently reduced the number of crossings in OFT, whereas Aliskiren pretreatment (10 mg/kg, i.p.) attenuated the LPS effect for two hours after LPS injection. The treatments did not show effects on locomotor activity in OFT 24 h after LPS administration. LPS increased the immobility time in TST and FST or reduced sucrose consumption in SPT after 24 h. Aliskiren reversed the effects induced by LPS in TST, FST, and SPT. CD11 b mRNA, a microglial marker, GFAP mRNA, an astroglial marker, and proinflammatory cytokines genes (TNF-α, IL-1β, and IL-6) were upregulated in the prefrontal cortex in LPS exposed animals. However, Aliskiren reduced LPS-induced inflammatory genes in the prefrontal cortex. Hence, the outcomes conclude that Aliskiren prevents depressive illness associated with neuroinflammation in humans.

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The purpose of this systematic review was to investigate the scientific evidence to support the use of direct renin inhibitors (DRIs) in diabetic nephropathy (DN). MEDLINE was searched for articles reported until 2018. A standardized dataset was extracted from articles describing the effects of DRIs on plasma renin activity (PRA) in DN. A total of three clinical articles studying PRA as an outcome measure for DRIs use in DN were identified. These clinical studies were randomized controlled trials (RCTs): one double-blind crossover, one post hoc of a double-blind and placebo-controlled study, and one open-label and parallel-controlled study. Two studies reported a significant decrease of albuminuria associated with PRA reduction. One study had a DRI as monotherapy compared with placebo, and two studies had DRI as add-in to an angiotensin II (Ang II) receptor blocker (ARB). Of 10,393 patients with DN enrolled in five studies with DRI, 370 (3.6%) patients had PRA measured. Only one preclinical study was identified that determined PRA when investigating the effects of aliskiren in DN. Moreover, most of observational preclinical and clinical studies identified report on a low PRA or hyporeninemic hypoaldosteronism in DM. Renin inhibition has been suggested for DN, but proof-of-concept studies for this are scant. A small number of clinical and preclinical studies assessed the PRA effects of DRIs in DN. For a more successful translational research for DRIs, specific patient population responsive to the treatment should be identified, and PRA may remain a biomarker of choice for patient stratification.

Renin is the rate‐limiting enzyme of the renin–angiotensin system cascade, which drives the pathophysiological progression of heart failure. Species differences in the amino acid sequence of the catalytic domain of renin limit evaluations of the potency and efficacy of human renin inhibitors in animal models, and a high dose of inhibitors is usually needed to show its organ‐protective effects in rodents. In the present study, we developed a novel murine heart failure model (triple‐tg) to enable us to evaluate the cardioprotective effect of renin inhibitors at more relevant doses for humans, by cross‐breeding calsequestrin transgenic (CSQ‐tg) mice with human renin and human angiotensinogen double‐transgenic mice. The triple‐tg mice exhibited increased plasma renin activity, worsened cardiac hypertrophy, and higher mortality compared to CSQ‐tg mice. Triple‐tg mice treated with 10 mg·kg−1 of TAK‐272 (imarikiren/SCO‐272), an orally active direct renin inhibitor, exhibited improvements in heart failure phenotypes, such as cardiac hypertrophy and survival rate; however, a dose of 300 mg·kg−1 was required to improve symptoms in CSQ‐tg mice. Our results suggest that this newly generated triple‐tg heart failure model is useful to evaluate the cardioprotective effects of human renin inhibitors at clinically relevant doses, thereby minimizing the concerns of off‐target effects related to much higher drug exposure than that achieved in clinical study. [ABSTRACT FROM AUTHOR]

Background/Aims: We have reported that the long-term administration of angiotensin II receptor blockers (ARBs) induced unusual proliferative changes of renal afferent arteriolar smooth muscle cells (SMCs) in rats, associated with the overproduction of renin. In this study, we examined that a direct renin inhibitor (DRI: Aliskilen; Novartis Pharma Co, USA) might induce different changes on afferent arteriolar walls compared to ARBs. Method: Twenty one 6-weeks-old male spontaneous hypertensive rats (SHRs) were divided into the following three groups: high-dose DRI group (n=7), low-dose DRI group (n=5) and control group (n=9). The rats were fed a standard diet (0.4%NaCl) containing high-dose (150mg/kg/day), low-dose (30mg/kg/day) DRI and without DRI for 12 weeks. The kidneys were examined by histological and immunohistochemical studies. Systolic blood pressure, 24-h urine samples and blood samples were also examined. Results: The afferent arteriolar SMC walls in the two DRI groups showed no proliferative changes. The positive renin expression area was the largest in the high-dose DRI group among the three groups (14.3±4.0µm2, 6.7±2.0µm2, 2.6±0.9µm2/glomerlus, p=0.020, p=0.008, p=0.017, respectively). Conclusion: The long-term DRI administration increases tissue and circulatory renin; however, afferent arteriolar proliferative changes as shown in ARBs were not induced.

We previously identified 2- tert -butyl-4-[(3-methoxypropyl)amino]- N -(2-methylpropyl)- N -[(3 S ,5 R )-5-(morpholin-4-ylcarbonyl)piperidin-3-yl]pyrimidine-5-carboxamide 3 as a potent renin inhibitor. Since 3 showed unacceptably low bioavailability (BA) in rats, structural modification, using SBDD and focused on physicochemical properties was conducted to improve its PK profile while maintaining renin inhibitory activity. Conversion of the amino group attached at the 4-position of pyrimidine to methylene group improved PK profile and decreased renin inhibitory activity. New central cores with carbon side chains were explored to improve potency. We had designed a series of 5-membered azoles and fused heterocycles that interacted with the lipophilic S3 pocket. In the course of modification, renin inhibitory activity was enhanced by the formation of an additional hydrogen bonding with the hydroxyl group of Thr77. Consequently, a series of novel benzimidazole derivatives were discovered as potent and orally bioavailable renin inhibitors. Among those, compound 13 exhibited more than five-fold of plasma renin inhibition than aliskiren in cynomolgus monkeys at dose ratio. [ABSTRACT FROM AUTHOR]

A 19-year-old female patient presented refractory disabling loin pain associated with mild kidney atrophy (split renal function of 33%). Investigation revealed elevated serum renin level; a therapeutic test with oral renin inhibitor was tried, obtaining important pain control. Aiming to resolve the symptom while preserving the patient kidney and attributing the pain mechanism to be associated with the abnormal renin production, a laparoscopic kidney denervation was performed with no complications and complete pain resolution.

A novel approach was conducted for fragment-based lead discovery and applied to renin inhibitors. The biochemical screening of a fragment library against renin provided the hit fragment which showed a characteristic interaction pattern with the target protein. The hit fragment bound only to the S1, S3, and S3 SP (S3 subpocket) sites without any interactions with the catalytic aspartate residues (Asp32 and Asp215 (pepsin numbering)). Prior to making chemical modifications to the hit fragment, we first identified its essential binding sites by utilizing the hit fragment’s substructures. Second, we created a new and smaller scaffold, which better occupied the identified essential S3 and S3 SP sites, by utilizing library synthesis with high-throughput chemistry. We then revisited the S1 site and efficiently explored a good building block attaching to the scaffold with library synthesis. In the library syntheses, the binding modes of each pivotal compound were determined and confirmed by X-ray crystallography and the library was strategically designed by structure-based computational approach not only to obtain a more active compound but also to obtain informative Structure Activity Relationship (SAR). As a result, we obtained a lead compound offering synthetic accessibility as well as the improved in vitro ADMET profiles. The fragments and compounds possessing a characteristic interaction pattern provided new structural insights into renin’s active site and the potential to create a new generation of renin inhibitors. In addition, we demonstrated our FBDD strategy integrating highly sensitive biochemical assay, X-ray crystallography, and high-throughput synthesis and in silico library design aimed at fragment morphing at the initial stage was effective to elucidate a pocket profile and a promising lead compound. [ABSTRACT FROM AUTHOR]

The action of the aspartyl protease renin is the rate-limiting initial step of the renin-angiotensin-aldosterone system. Therefore, renin is a particularly promising target for blood pressure as well as onset and progression of cardiovascular and renal diseases. New pyrimidine derivatives 5 – 14 were designed in an attempt to enhance the renin inhibitory activity of compound 3 identified by our previous fragment-based drug design approach. Introduction of a basic amine essential for interaction with the two aspartic acids in the catalytic site and optimization of the S1/S3 binding elements including an induced-fit structural change of Leu114 (‘Leu-in’ to ‘Leu-out’) by a rational structure-based drug design approach led to the discovery of N -(piperidin-3-yl)pyrimidine-5-carboxamide 14 , a 65,000-fold more potent renin inhibitor than compound 3 . Surprisingly, this remarkable enhancement in the inhibitory activity of compound 14 has been achieved by the overall addition of only seven heavy atoms to compound 3 . Compound 14 demonstrated excellent selectivity over other aspartyl proteases and moderate oral bioavailability in rats. [ABSTRACT FROM AUTHOR]

Karl AndersenDepartment of Medicine, Division of Cardiology, Landspitali University Hospital, University of Iceland, Reykjavik, IcelandAbstract: The overall purpose of hypertension treatment is 2-fold. First, patients often have symptoms that are related to their high blood pressure and although subtle in many instances may be improved dramatically by blood pressure control. The main reason for blood pressure treatment, however, is to reduce the burden of cardiovascular complications and end organ damage related to the condition. This may be considered the ultimate goal of blood pressure treatment. In this respect, actual blood pressure measurements may be seen as surrogate end points as the organ protective effects of two antihypertensive agents may differ significantly even though their blood pressure lowering effects are similar. Thus beta-blockers, once seen as first-line treatment of hypertension for most patients, now are considered as third- or fourth-line agents according to the latest NICE guidelines (National Institute for Health and Clinical Excellence, www.nice.org.uk/CG034). On the other hand, agents that inhibit the activity of the renin-angiotensin-aldosterone system (RAAS) are being established as safe, effective and end organ protective in numerous clinical trials, resulting in their general acceptance as first-line treatment in most patients with stage 2 hypertension. This shift in emphasis from beta-blockers and thiazide diuretics is supported by numerous clinical trials and has proven safe and well tolerated by patients. The impact of this paradigm shift will have to be established in future long-term randomized clinical trials. The optimal combination treatment with respect to end organ protection has yet to be determined. Most combinations will include either a RAAS active agent and calcium channel blocker or two separate RAAS active agents working at different levels of the cascade. In this respect direct renin inhibitors and angiotensin receptor blockers seem particularly promising but the concept awaits evaluation in upcoming randomized clinical trials. Although safety data from the randomized clinical trials to date have been promising, we still lack data on the long-term effect of aliskiren on mortality and there still are patient groups where the safety of aliskiren is unexplored.Keywords: aliskiren, elderly, hypertension, renin-angiotensin-aldosterone system