Effects of a novel ACE inhibitor, 3-(3-thienyl)-l-alanyl-ornithyl-proline, on endothelial vasodilation and hepatotoxicity in l-NAME-induced hypertensive rats

The role of Kolaviron, a bioflavonoid from Garcinia kola, in the management of cardiovascular diseases: A systematic review

While the cardiovascular effects of Kolaviron (KV) and Garcinia kola (GK) are documented in the literature, a thorough search through literature revealed a fragmentation of information on the effect of KV and GK on cardiovascular diseases (CVDs). This systematic review aims to evaluate and summarize preclinical or clinical evidence on the effect of KV and GK on CVDs. Using the PRISMA guidelines, a systematic literature search was conducted in five medical databases (PubMed, Cochrane, EMBASE, CINAHL, and Web of Science). Inclusion criteria included both in vivo and in vitro studies related to CVDs. Eligible studies included those in which specific clinical parameters, CVD biomarkers, or voltage-gated channel effects were reported. The quality of the included studies was assessed using a modified Collaborative Approach to Meta-Analysis and Review of Animal Data from the Experimental Studies (CAMARADE) checklist. A total of 22 studies were included in this systematic review. The median and mean values of the included studies' quality scores were 6 and 5.864 ± 0.296, respectively. The results from the quality assessment of included studies validate their suitability, usefulness, and fit. Based on this systematic review, the effect of KV and GK on CVDs can be divided into eight emerging trends: (1) Anti-hypertensive/Blood pressure lowering effect; (2) Lipid profile improvement effect (3) Anti-atherosclerotic effect; (4) Anti-thrombotic effect; (5) Cardioprotection; (6) Vasodilatory effect; (7) Antioxidant effects; and (8) Genetic expression and therapeutic target for cardiovascular dysfunction. From this systematic review, it can be concluded that KV is helpful in managing CVD risk factors such as hypertension and high lipids/cholesterol. Several included studies in this review demonstrated the antihypertensive, lipid improvement, antioxidant, and signaling pathway modulation effects of KV. This potentially makes KV a good therapeutic target for the management of CVDs.

Potential antihypertensive activity of novel peptides from green basil leaves

Hypertension is among the risk factors of death globally. Novel antihypertensive peptides are alternative choices of antihypertensive assistance. This study aimed to discover novel antihypertensive peptides from green basil leaves. Two bioactive peptides with high angiotensin-converting enzyme inhibition (Asp-Leu-Ser-Ser-Ala-Pro; peptide 1) and antioxidant (Asp-Ser-Val-Ser-Ala-Ser-Pro; peptide 2) activities were gavaged to male Wistar rats induced with NG-nitro-l-arginine methyl-ester (L-NAME). L-NAME-treated rats (HT) had decreased body weights and levels of nitrite and nitrate, which are metabolites of nitric oxide. The levels of their glucose and liver function indicators increased as compared to normal rats. HT rats receiving antihypertensive drugs (HTD) showed higher low-density lipoprotein and low-density lipoprotein/high-density lipoprotein levels than HT rats. Peptide 1 seems to benefit the rat lipid profiles, liver functions, antioxidant, nitrite, nitrate, and angiotensin II peptide levels but not peptide 2. In conclusion, our findings indicate the antihypertensive potential related to vasodilation of peptides from green basil leaves.

Co-administration of metformin and/or glibenclamide with losartan reverse NG-nitro-l-arginine-methyl ester-streptozotocin-induced hypertensive diabetes and haemodynamic sequelae in rats

Over the years, there have been opinions on whether to reduced blood pressure (BP) to a different levels in patients with diabetes mellitus. Hence, this study investigated the efficacy of the co-administration of losartan (angiotensin receptor blocking antihypertensive agent) with metformin and/or glibenclamide (antidiabetic agents) on hypertensive-diabetic experimental rats induced by N^G-nitro-l-arginine-methyl-ester hydrochloride (l-NAME), and streptozotocin (STZ). STZ (45 mg/kg, i.p.)-induced diabetic rats combined with l-NAME (40 mg/kg, p.o.)-induced hypertension were allotted into different groups. Group 1 received distilled water (10 mL/kg) and served as normal control, group 2 comprised hypertensive diabetic rats with distilled water, groups 3-5 were hypertensive-diabetic rats but received combination treatments of losartan + metformin, losartan + glibenclamide, and losartan + metformin + glibenclamide daily for 8 weeks, respectively. Our finding revealed no changes in the body weights, but there was a significant increase in fasting blood sugar levels in l-NAME - STZ-induced hypertensive-diabetes, which were lowered by losartan + metformin, losartan + glibenclamide, and losartan + metformin + glibenclamide treatments. Moreover, the increased systolic-BP, mean arterial pressure but not diastolic-BP and heart rate by l-NAME + STZ were attenuated more significantly by losartan + metformin + glibenclamide between weeks 2-8 relative to hypertensive-diabetic control. l-NAME + STZ-induced elevated levels of lactate dehydrogenase and creatinine kinase, were differentially reversed by losartan + metformin, losartan + glibenclamide, and losartan + metformin + glibenclamide. However, l-NAME + STZ-induced decreased nitrite level was significantly restored by all treatments, suggesting increased nitrergic transmission. Additionally, l-NAME + STZ-induced degeneration of pancreatic islet and myocardial cells were dramatically alleviated by losartan + metformin + glibenclamide treatments. Our findings suggest hyperglycemia with raised systolic-BP should be managed with losartan combined with both metformin and glibenclamide than single combination of losartan with antidiabetics.

Angiotensin converting enzyme inhibitor potentiates the hypoglycaemic effect of NG-nitro-L-arginine methyl ester (L-NAME) in rats

The inhibition of renin angiotensin system pathway has been largely documented to be effective in the control of cardiovascular events. The present study investigated the effect of angiotensin converting enzyme (ACE) inhibitor on fasting blood glucose level in hypertension induced by the inhibition of nitric oxide synthase (NOS) in male Wistar rats. Hypertension was induced by the inhibition of NOS using a non-selective NOS inhibitor, NG-nitro-L-arginine methyl ester (L-NAME). The blockade of NOS resulted in an increase in blood pressure, ACE, angiotensin II and endothelin-1 levels, and a decrease in fasting blood glucose and nitric oxide (NO) levels. The hypertensive rats treated with ACE inhibitor (ramipril) recorded a decrease in blood pressure, ACE, angiotensin II, endothelin-1, NO and fasting blood glucose levels, and an increase in prostacyclin level. In conclusion, ACE inhibitor potentiated the hypoglycaemic effect of NOS inhibitor and this effect is independent of NO and pancreatic insulin release.

Involvement of shedding induced by ADAM17 on the nitric oxide pathway in hypertension

A Disintegrin and Metalloprotease 17 (ADAM17), also called tumor necrosis factor-ɑ (TNF-ɑ) convertase (TACE), is a well-known protease involved in the sheddase of growth factors, chemokines and cytokines. ADAM17 is also enrolled in hypertension, especially by shedding of angiotensin converting enzyme type 2 (ACE2) leading to impairment of angiotensin 1–7 [Ang-(1–7)] production and injury in vasodilation, induction of renal damage and cardiac hypertrophy. Activation of Mas receptor (MasR) by binding of Ang-(1–7) induces an increase in the nitric oxide (NO) gaseous molecule, which is an essential factor of vascular homeostasis and blood pressure control. On the other hand, TNF-ɑ has demonstrated to stimulate a decrease in nitric oxide bioavailability, triggering a disrupt in endothelium-dependent vasorelaxation. In spite of the previous studies, little knowledge is available about the involvement of the metalloprotease 17 and the NO pathways. Here we will provide an overview of the role of ADAM17 and Its mechanisms implicated with the NO formation.

Moringa seed-supplemented diets modulate ACE activity but not its gene expression in L-NAME-induced hypertensive rats

Introduction: We investigated the effect of dietary inclusions of Moringa seed (5% and 10%) on blood pressure, angiotensin-1 converting enzyme (ACE) activity, and gene expression, as well as redox status in hypertensive rats.Material and methods: Wistar strain albino rats were fed moringa seed-based diets for two weeks prior L-NAME (40 mg/kg/day, p.o.) administration for another ten days. Subsequently, the blood pressure was monitored. Furthermore, the kidney homogenates were assayed for ACE activity and gene expression, as well as oxidative stress markers.Results: The increased (systolic =297 ± 59.30 mmHg; diastolic= 242 ± 51.96 mmHg) blood pressure, arginase activity, and reduced nitric oxide level were significantly ameliorated in hypertensive rats treated with the seed. However, the elevated ACE activity was significantly reduced but not the upregulated ACE1 gene. Also, the reduced antioxidant enzyme activities were ameliorated with a significant downregulation in their regulator-Nrf2. Rutin (4.07 ± 0.02 mg/g) and quercitrin (4.06 ± 0.01 mg/g), among others, were found in the seed.Discussion: This study suggests that moringa seed offers its antihypertensive properties by acting as an ACE inhibitor but not its gene modulator, and also modulates the antioxidant system through interaction with Nrf2.Conclusion: Moringa seed could act as an ACE inhibitor and not its gene modulator.

A Comparative Study of the Antihypertensive and Cardioprotective Potentials of Hot and Cold Aqueous Extracts of Hibiscus sabdariffa L. in Relation to Their Metabolic Profiles

Ethnopharmacological relevance: Since ancient times, Hibiscus sabdariffa L. calyces have been used as a folk remedy for the treatment of hypertension. However, it is questionable as to whether there is a difference in the antihypertensive activity of the hot or cold aqueous extracts.

Aim of the study: We designed this study to specify the best method for water extraction of the antihypertensive metabolites of H. sabdariffa and to confirm their in vivo antihypertensive capabilities.

Materials and methods: The powdered dried calyces of H. sabdariffa were independently extracted with cold and hot water. A comparative study was performed between the cold and hot aqueous extracts of H. sabdariffa based on evaluation of the in vitro renin and angiotensin-converting enzyme (ACE) inhibition activities. Additionally, both extracts were subjected to an in vivo study for the evaluation of their antihypertensive activities in L-N^w-Nitro arginine methyl ester (L-NAME)–induced hypertensive rats. Further, a metabolomics study was also performed for both extracts to identify their chemical constituents.

Results: The cold and hot extracts significantly reduced the angiotensin II, ACE, and aldosterone levels in the plasma. Furthermore, in the myocardium and aorta, decreased iNOS (inducible nitric oxide synthase) levels and elevated eNOS (endothelial nitric oxide synthase), as well as the rise in plasma NO levels, were reported with both extracts, but better results were displayed with the hot extract, leading to a potential antihypertensive effect. Additionally, the cold and hot Hibiscus extracts induced a cardioprotective effect through reducing necrosis, inflammation, and vacuolization that results from the induction of hypertension, an effect that was more prominent with the hot extract. Moreover, a comprehensive metabolomics approach using ultra-performance liquid chromatography coupled to tandem mass spectrometry (UPLC–MS/MS) was able to trace the metabolites in each extraction.

Conclusion: The extracts showed different anthocyanin and phenolic compounds, but the hot extract showed higher contents of specific phenolics to which the superior antihypertensive and cardioprotective activities could be related.

Butterfly Pea Flower (Clitoria ternatea Linn.) Extract Ameliorates Cardiovascular Dysfunction and Oxidative Stress in Nitric Oxide-Deficient Hypertensive Rats

In this study, we examine whether Clitoria ternatea Linn. (CT) can prevent Nω-nitro-L-arginine methyl ester hydrochloride (L-NAME)-induced cardiac and vascular dysfunction in rats. Male Sprague Dawley rats were given L-NAME (40 mg/kg, drinking water) and orally administered with CT extract (300 mg/kg/day) or lisinopril (2.5 mg/kg/day) for 5 weeks. The main phytochemical components of the CT extract were found to be flavonoids. The CT extract alleviated the high blood pressure in rats receiving L-NAME. Decreased vasorelaxation responses to acetylcholine and enhanced contractile responses to sympathetic nerve stimulation in aortic rings and mesenteric vascular beds of L-NAME treated rats were ameliorated by CT extract supplementation. Left ventricular hypertrophy and dysfunction were developed in L-NAME rats, which were partially prevented by CT extract treatment. The CT extract alleviated upregulated endothelial nitric oxide synthase expression, decreased plasma nitrate/nitrite levels, and increased oxidative stress in L-NAME rats. It suppressed high levels of serum angiotensin-converting enzyme activity, plasma angiotensin II, and cardiac angiotensin II type 1 receptor, NADPH oxidases 2, nuclear factor-kappa B, and tumor necrosis factor-alpha expression. The CT extract, therefore, partially prevented L-NAME-induced hypertension and cardiovascular alterations in rats. These effects might be related to a reduction in the oxidative stress and renin-angiotensin system activation due to L-NAME in rats.

Hypertensive Rats Treated Chronically With Nω-Nitro-L-Arginine Methyl Ester (L-NAME) Induced Disorder of Hepatic Fatty Acid Metabolism and Intestinal Pathophysiology

N^ω-nitro-L-arginine methyl ester (L-NAME), an inhibitor of nitric oxide (NO) biosynthesis, results in hypertension and liver injury. This study aimed at investigating the changes of liver lipometabonomics and exploring the underlying mechanisms of liver injury in the L-NAME-treated rats. The male Sprague-Dawley (SD) rats were treated with L-NAME (40 mg/kg, p.o.) for 8 weeks. After that, the liver, aorta, fecal, and serum were collected for analysis. The results showed that L-NAME induced hypertension and disordered the endothelial nitric oxide synthase (eNOS)-NO pathway in the treated rats. L-NAME could also increase the levels of serum total cholesterol (TC), triglyceride (TG), alanine transaminase (ALT), and aspartate transaminase (AST). The multidimensional mass spectrometry-based shotgun lipidomics (MDMS-SL) analysis showed that L-NAME could induce significant changes of the total hepatic lipids and most hepatic triglycerides, as well as fatty acid (FA). A positive correlation was found between the blood pressure and TAG. Immunofluorescence and Western-Blot experiments indicated that the L-NAME treatment significantly influenced some FA β-oxidation, desaturation, and synthesis-related proteins. The increase of intestinal inflammation, decrease of microcirculation and tight junction proteins, as well as alterations of microbial communities were observed in the L-NAME induced hypertensive rats, as well as alterations of microbial communities were notable correlation to TAG and FA species. This study demonstrated that the L-NAME-induced hypertensive rats exhibiting liver injury were the joint action of hepatic abnormal fatty acid metabolism and microcirculation disorder. Furthermore, the gut microflora, as well as the changes of FA β-oxidation (ACOX, CPT1α), desaturation (SCD-1), and synthesis (FAS) may be the potential mechanisms for abnormal fatty acid metabolism.

Nobiletin alleviates vascular alterations through modulation of Nrf-2/HO-1 and MMP pathways in l-NAME induced hypertensive rats

Nobiletin alleviates l-NAME-induced vascular dysfunction and remodeling and superoxide production in rats.

Reduction in nitric oxide bioavailability shifts serum lipid content towards atherogenic lipoprotein in rats

Nitric oxide (NO) is major endothelial relaxing factor and reduction in its bioavailabilty has been linked to hypertension. Furthermore, high lipid content is a strong risk factor predisposing to cardiovascular diseases. The principal focus of this study was to investigate the effect of blockade of nitric oxide synthase (NOS) on serum lipid content in rats. Male Wistar rats (150-170 g, n = 15) were randomly divided into two groups designated control (n = 5), and L-Name group (n = 10) and were gavage with distilled water and 60 mg/kg of L-NAME respectively daily for three weeks. After 3 weeks, the L-NAME group was sub-divided into two sub-groups (n = 5 each): L-NAME (60 mg/kg of L-NAME), and L-NAME plus ramipril (LR) (60 mg/kg of L-NAME plus 20 mg/kg of ramipril) and were treated daily for another three weeks. The blood pressure (BP) of the conscious rats was measured by tail-cuff method at the onset, at the third and at the sixth weeks of the experiment; while serum lipid contents and NO were measured at the third and sixth weeks. At the end of the experiment blood sample was drawn by ocular puncture for evaluation of lipid profile and NO, and the animals were later euthanized by overdose of anaesthesia. Data were analyzed using ANOVA at p < 0.05. There was a significant increase in BP, triglyceride, total cholesterol, low density lipoprotein-cholesterol, and atherogenic indices in L-NAME group compared to the control and LR group (p < 0.05); NO and high density lipoprotein-cholesterol was significant lower in the L-NAME group compared to control and LR (p < 0.05). In conclusion, reduction in NO bioavailability alters lipid metabolism, which was rectified by ramipril.