Thromboxane-B2, prostaglandin-E2 and hypertension in the rat 2-kidney 1-clip model: a possible mechanism of the garlic induced hypotension

LDL-Cholesterol-Lowering Effects of a Dietary Supplement Containing Onion and Garlic Extract Used in Healthy Volunteers

Hypercholesterolemia plays a pivotal role in the development and progression of cardiovascular diseases, and its prevention seems to be a crucial healthcare strategy to ameliorate these conditions. Subjects with mild hypercholesterolemia are frequently advised against using cholesterol-lowering drugs due to potential side effects, with an emphasis instead on prioritizing dietary adjustments and lifestyle modifications as the primary strategy. In this context, the use of dietary supplements based on medicinal plants may be recommended as a complementary approach to managing elevated cholesterol levels. The aim of this study was to investigate the safety and potential therapeutic effectiveness of a standardized formulation containing extracts from garlic and onions in addressing the health concerns of individuals with slightly elevated cholesterol levels. A controlled, randomized, double-blind, two parallel-group study was conducted over 8 weeks, with clinical visits scheduled at baseline, weeks 2 and 4, as well as at the end of the study. The results revealed significant reductions in both low-density lipoprotein cholesterol and total cholesterol levels among participants who received the extract. Additionally, improvements in blood pressure, as well as in oxidative and inflammatory markers were observed, thus suggesting its potential as a valuable therapeutic intervention for managing mild hypercholesterolemia.

Dietary inflammation index association with serum levels of nitric oxide, prostacyclin, and thromboxane B2 among prinzmetal angina patients and healthy persons

BACKGROUND AND AIM

This study aimed to assess the association between dietary inflammation index with serum Nitric oxide, Prostacyclin, and Thromboxane B2 among Prinzmetal angina patients and healthy persons.

METHODS AND RESULTS

This case-control study was conducted among 120 Prinzmetal angina patients and 120 healthy persons referred to the Ardabil Imam Khomeini Hospital between 2021 and 2022. Blood samples were gained from all study participants for measurement of serum Nitric oxide, Prostacyclin, and Thromboxane B2. The serum Nitric oxide in patients who had higher DII was less than in patients with less dietary inflammation index (β = -0.75 p = 0.02). The serum Prostacyclin level in patients with greater dietary inflammation index was 0.68 ng/ml less than in patients with less dietary inflammation index (β = -0.68 p = 0.04). The level of serum Thromboxane B2 had a positive association with dietary inflammation index (β = 0.81 p = 0.04).

CONCLUSION

In Prinzmetal angina patients, more dietary inflammation index can increase the serum Thromboxane B2 and decrease the serum Nitric oxide and Prostacyclin. More clinical trial study is needed to confirm these results.

Iranian traditional medicinal plants for management of chronic heart failure: A review

Chronic heart failure is a public health problem with a high prevalence worldwide and an important topic in clinical cardiology. Despite of advances in the drug treatment strategy for heart failure, the number of deaths from this condition continues to rise. It will be a renewed focus on preventing heart failure using proven and perhaps novel drugs. Management will also focus on comorbid conditions that may influence the progression of the disease. Traditional medicine has a potential to introduce different approaches for treatment of some disorders. We here reviewed top medicinal plants, according to traditional medicine to experimental studies, and their potency for the treatment of chronic heart failure based on the evidence of their functions.

Effect of garlic extract on markers of lipid metabolism and inflammation in coronary artery disease (CAD) patients: A systematic review and meta-analysis

Several preclinical studies have focused on the beneficial effects of garlic on cardiovascular diseases, but the results were inconsistent. We performed a systematic review and meta-analysis on the effect of garlic powder tablets and aged garlic extract (AGE) in CAD patients, mainly focusing on blood pressure, coronary artery calcification, lipid profile, and inflammatory markers. We searched PubMed, Cochrane CENTRAL, and Google Scholar to identify randomized controlled trials which examined garlic's effect on CAD patients. The standardized mean difference with 95% CI was calculated using fixed-effect or random-effect models. Garlic has shown statistically significant changes of HDL (SMD = 0.18; 95% CI = -0.00 to 0.37; p = .05); LDL (SMD = -0.27; 95% CI = -0.46 to -0.08; p = .004), apolipoprotein-A (SMD = 0.68; 95% CI = 0.24 1.13; p = .002), C-RP (SMD = -0.59; 95% CI = -0.92 to -0.25; p = .0007), IL-6 (SMD = -1.08; 95% CI = -2.17 to 0.01; p = .05), homocysteine (SMD = -0.66; 95% CI = -1.04 to -0.28; p = .0007) and CAC score (SMD = -1.61; 95% CI = -2.66 to -0.57; p = .003). In the case of subgroup analysis, the overall effect was significantly effective in reducing TC, LDL levels and improving HDL levels in CV risk patients. Our study findings provide consistent evidence that intake of garlic reduces CVD risk factors. However, garlic could be considered a safe natural medicine to debilitate inflammation in CAD patients.

Herbs and their bioactive ingredients in cardio-protection: Underlying molecular mechanisms and evidences from clinical studies

BACKGROUND

Medicinal plants or herbs produce a bounty of bioactive phytochemicals. These phytochemicals can influence a variety of physiological events related to cardiovascular health through multiple underlying mechanisms, such as their role as antioxidative, anti-ischemic, anti-proliferative, hypotensive, anti-thrombotic, and anti-hypercholesterolemic agents.

PURPOSE

The purpose of this review is to summarize and connect evidences supporting the use of phytotherapy in the management of some of the most common cardiovascular impairments, molecular mechanisms underlying cardio-protection mediated by herbs, and clinical studies which are positively linked with the use of herbs in cardiovascular biology. Additionally, we also describe several adverse effects associated with some of the herbal plants and their products to provide a balanced set of studies in favor or against phytotherapy in cardiovascular health that may help global discourses on this matter.

METHODS

Studies relating to the use of medicinal plants were mined by strategically searching scientific databases including Google Scholar, PubMed and Science Direct. Investigations involving approximately 175 articles including reviews, research articles, meta-analyses, and cross-sectional and observational studies were retrieved and analyzed in line with the stated purpose of this study.

RESULTS

A positive correlation between the use of medicinal plants and cardiovascular health was observed. While maintaining cardiovascular physiology, medicinal plants and their derivatives seem to govern a variety of cellular mechanisms involved in vasoconstriction and vasorelaxation, which in turn, are important aspects of cardiovascular homeostasis. Furthermore, a variety of studies including clinical trials, cross-sectional studies, and meta-analyses have also supported the anti-hypertensive and thus, cardio-protective effects, of medicinal plants. Apart from this, evidence is also available for the potential drawbacks of several herbs and their products indicating that the unsupervised use of many herbs may lead to severe health issues.

CONCLUSIONS

The cardio-protective outcomes of medicinal plants and their derivatives are supported by ever-increasing studies, while evidences exist for the potential drawbacks of some of the herbs. A balanced view about the use of medicinal plants and their derivative in cardiovascular biology thus needs to be outlined by researchers and the medical community. The novelty and exhaustiveness of the present manuscript is reflected by the detailed outline of the molecular basis of "herbal cardio-protection", active involvement of several herbs in ameliorating the cardiovascular status, adverse effects of medicinal plants, and the clinical studies considering the use of phytotherapy, all on a single platform.

Medicinal Plants as a Potential and Successful Treatment Option in the Context of Atherosclerosis

Atherosclerosis is a chronic multifactorial disease characterized by mainly changes of blood lipids profile and inflammation in vessel wall. The cardiovascular disease based on atherosclerosis is currently the leading cause of mortality in developed countries. Therefore, timely prevention and therapy of atherosclerosis are able to reduce the risk of the development of its clinical manifestations. Anti-atherosclerotic activity of medicinal plants mainly appears in their multiple effects such as anti-inflammatory, antioxidant, anti-atherogenic, hypotensive, lipid-lowering, anti-thrombotic. Moreover, most of medicinal plants are characterized by their pleiotropic anti-atherosclerotic action. In addition, the medicinal plants-derived pharmacological substances and/or compounds are characterized by relative safety and fewer side effects that allows considering them as one of potential anti-atherosclerotic effective agents. The direct anti-atherosclerotic effect of some medicinal plants was confirmed in clinical trials of carotid Intima-media thickness (IMT) progression during long-term medication with medicinal plants. This review attempted to determine the current status of the databases PubMed and Scopus (until November, 2019) to investigate the medicinal plants possessing anti-atherosclerotic activity in experimental and clinical studies.

Therapeutic effects of garlic in cardiovascular atherosclerotic disease

Garlic (Allium sativum) is a widely known medicinal plant, potential of which remains to be fully evaluated. Its wide-range beneficial effects appear to be relevant for treatment and prevention of atherosclerosis and related diseases. It is generally believed that garlic-based preparations are able to improve lipid profile in humans, inhibit cholesterol biosynthesis, suppress low density lipoprotein oxidation, modulate blood pressure, suppress platelet aggregation, lower plasma fibrinogen level and increase fibrinolytic activity, thus providing clinically relevant cardioprotective and anti-atherosclerotic effects. It is important to assess the level of evidence available for different protective effects of garlic and to understand the underlying mechanisms. This information will allow adequate integration of garlic-based preparations to clinical practice. In this review, we discuss the mechanisms of anti-atherosclerotic effects of garlic preparations, focusing on antihyperlipidemic, hypotensive, anti-platelet and direct anti-atherosclerotic activities of the medicinal plant. We also provide an overview of available meta-analyses and a number of clinical trials that assess the beneficial effects of garlic.

Allium vegetable intakes and the incidence of cardiovascular disease, hypertension, chronic kidney disease, and type 2 diabetes in adults: a longitudinal follow-up study

OBJECTIVES

This study investigated the association between habitual consumption of allium vegetables (garlic and onion) and the incidence of cardiovascular disease (CVD) outcomes, hypertension (HTN), chronic kidney disease (CKD), and type 2 diabetes (T2D).

METHODS

Adult men and women, participated in the Tehran Lipid and Glucose Study (2006-2008 to 2012-2014), were recruited. Habitual dietary intakes were assessed using a validated semiquantitative food frequency questionnaire. Demographics, anthropometrics, blood pressure, and biochemical variables were evaluated at baseline and during follow-up examinations. Multivariate Cox proportional hazard regression models adjusted for potential confounders were used to estimate the development of CVD outcomes, HTN, CKD, and T2D in relation to allium vegetable intakes.

RESULTS

Mean age of participants (44.2% men) was 40.3 ± 14.3 years, at baseline. During an average of 6 years of follow-up, the incidence rate of CVD outcomes, HTN, CKD, and T2D were 3.3, 15.5, 17.9, and 6.7%, respectively. A higher habitual intake of allium vegetables was associated with a 64% reduced risk of CVD outcomes (hazard ratio = 0.36, 95% confidence interval, CI = 0.18-0.71; P for trend = 0.011), 32% lower incidence of CKD (hazard ratio = 0.69, 95% CI = 0.46-0.98; P for trend = 0.11), and 26% decreased HTN development (hazard ratio = 0.74, 95% CI = 0.54-1.00; P for trend = 0.06). No significant association was observed between allium vegetable intakes and the risk of T2D. Allium vegetable intake was related to 6 years' changes of triglyceride levels (β = -0.81, P = 0.01) and creatinine clearance (β = 0.56, P = 0.01).

CONCLUSION

Data of the current study support the available mechanistic findings regarding cardiorenal protective properties of allium vegetables.

Garlic extract increases non-clipped kidney tubular natriuresis and diuresis in the 2-kidney, 1-clip rat model: Significance in hypertension

BACKGROUND

Angiotensin II (AngII) is a potent modulator of vascular tone and renal clearance function. Raw garlic aqueous extract (RGAE) inhibits angiotensin I converting enzyme (ACE) dipeptidase activity and therefore AngII generation in the 2-kidney, 1-clip rat model (2K-1Cr).

OBJECTIVE

This study investigated the effect of RGAE on the non-clipped kidney clearance function and blood pressure (BP) in the 2 K-1Cr.

METHOD

2K-1Cr were anesthetized, cannulated and instrumentalized and the acute effect during the first hour post-administration of a single intravenous dose of RGAE (30mg/100gb.wt/0.3ml) was tested on: 1- The ACE dipeptidase activity estimated from a reduction in the vasopressor action of angiotensin I [(AngI, 200ng/0.2ml): the precursor of AngII] in one group (n=5); 2- The non-clipped (left) kidney (LK) clearance function in a second group (n=6). Similar protocols were carried out on two groups of normal rats (Nr: n=5+n=6).

RESULTS

In the 2K-1Cr, RGAE partially, however significantly, decreased the vasopressor action of AngI. Furthermore, RGAE had no effect on systolic BP, mean BP, plasma osmolarity, LK cortical circulation or glomerular filtration rate. Alternatively, RGAE significantly increased LK urine volume, fractional excretion of water, sodium clearance and fractional excretion of sodium; while significantly decreasing heart rate and LK urine osmolarity.

CONCLUSIONS

Our findings suggest that a single i.v. dose of RGAE causes ACE dipeptidase inhibition, thus reducing AngII generation and bioavailability in the 2K-1Cr. This action of RGAE enhances the non-clipped kidney clearance of sodium and water by modulating the tubular handling mechanisms.

Complementary and Alternative Medicine Use in Hypertension

Thirty six percent of people in USA and Canada regularly use complementary and alternative medicine (CAM) for the prevention and treatment of different diseases, including hypertension. Generally, majority of the hypertensive patients do not disclose the use of such remedies, and also health care providers do not usually ask their hypertensive patients if they use CAM. The widespread consumption of CAM in hypertension requires clear understanding of their underlying mechanism of action, efficacy and safety. This chapter will provide a comprehensive list of CAM commonly used by Americans for the prevention and treatment of hypertension as well as their postulated mechanism of action. Modulation of drug metabolizing enzymes and their safety will also be covered along with the clinical consequences, i.e. drug-herb or herb-disease interactions. patients and healthcare providers should also be careful with using CAM therapies, because not only is there minimal evidence that several CAM products work to treat hypertension, but their safety hasn't been well-established.

Antihypertensive effect of allicin in dexamethasone-induced hypertensive rats

BACKGROUND

Glucocorticoid is among the most commonly prescribed medicine. Unfortunately, Excess glucocorticoid level leads hypertension in 80-90% patients. Garlic (Allium sativum) has been used since ancient times and even nowadays as a part of popular medicine for various ailments and physiological disorders. Hence this study was undertaken to investigate the antihypertensive activity of allicin in dexamethasone induced hypertension in wistar rats.

METHODS

The animals were randomly divided into four groups comprising of six rats per group. Hypertension was induced by subcutaneous injection of dexamethasone (10 μg/rat/day) in hypertensive rats. Two hypertensive group animals were treated with nicorandil (6 mg/kg/day, po) and allicin (8 mg/kg/day, po) respectively for 8 weeks. While systolic blood pressure (SBP) was measured by the tail-cuff method weekly up to 8 weeks.

RESULTS

Dexamethasone treatment resulted in significant increase in SBP while allicin treatment significantly decreases the SBP. Thus, this study confirmed that allicin treatment for 8 weeks partially reverse dexamethasone induced hypertension in rats. Allicin treatment also attenuated dexamethasone-induced anorexia and loss of total body weight.

CONCLUSION

This result suggests antihypertensive effects of allicin in dexamethasone induced hypertension. However, further studies are needed to explore the detailed mechanism of antihypertensive effect of allicin.

Does Garlic Supplementation Control Blood Pressure in Patients with Severe Coronary Artery Disease? A Clinical Trial Study

Background

Hypertension is one of the major risk factors for cardiovascular morbidities, including coronary artery disease (CAD).

Objectives

With interest on the important role of hypertension in the progression of CAD, this study was designed to estimate the effect of garlic powder tablets on the blood pressure (BP) in patients with severe CAD.

Methods

A randomized, placebo-controlled, clinical trial was conducted on 56 CAD patients, aged 25 - 75 years old. The patients were randomly divided into two groups: Galois groups (n = 27), receiving garlic powder tablet (400 mg garlic) twice daily and the placebo groups (n = 29), receiving placebo for 3 months. The BP was assessed at baseline and at the end of the study.

Results

During the 3 months study, in the placebo group, systolic BP (SBP) increased with 6.3 mmHg and diastolic BP (DBP) increased with 4.6 mmHg, changes which were significant. After the 3 months, the effect of garlic on SBP, after adjusting for baseline value, was significant, and this effect was more significant in hypertensive patients. Plasma lipids and lipoproteins did not change significantly in either the garlic or placebo groups, during the study. Tolerability, compliance and acceptability were high in all patients.

Conclusions

These results demonstrate that treatment with garlic-based drugs can be an effective treatment for controlling BP in CAD patients and has no interaction with other drugs that CAD patients take. Therefore, it may be considered as a safe adjunct treatment for this group of patients.

Anti-diabetic and anti-oxidant potential of aged garlic extract (AGE) in streptozotocin-induced diabetic rats

Background

Although aged garlic extract (AGE) shares some active components with fresh garlic and in spite of its palatability and milder side effects, the anti-diabetic and related anti-oxidant properties of AGE have not been investigated extensively, and the reported findings are inconsistent.

This study investigated the anti-diabetic effects of 3 incremental doses of AGE in streptozotocin (STZ)-induced diabetic rats (fasting blood sugar > 20 mM).

Method

Diabetic rats were divided into a control diabetic group (CD) and AGE-treated diabetic group (AGE-D). The AGE-D was divided into 3 groups and accordingly treated with AGE i.p. at 100, 300 and 600 mg/kg daily for 8 weeks. A control normal group (CN) was also included for reference.

Results

Compared to the CN group, the CD group showed significant loss of body weight (over 50 %); and decreased serum insulin concentration (10 fold) and total anti-oxidant level and catalase activity (45–70 %) in serum, kidney and liver. Conversely, the CD rats had an elevated blood glucose (nearly 4 fold), serum cholesterol (nearly 2 fold) and triglycerides (>2 fold), erythrocyte glycated hemoglobin (GHb, 3 fold) and kidney and liver lipid peroxidation (MDA levels). Treatment with AGE positively reversed the diabetic changes in the targeted parameters to levels significantly lower than those measured in the CD group and the degrees of attenuation were almost dose dependent especially with the two higher doses.

Conclusion

AGE exhibits a dose-dependent ameliorative action on indicators of diabetes in STZ-induced diabetic rats.

Antihypertensive effects of foods

Hypertension is one of the major risk factors for arteriosclerosis, which leads to cardiovascular disease and stroke. Several clinical trials revealed that control of the blood pressure is useful to reduce the morbidity and mortality associated with these diseases. However, the protective efficacy against these complications still remains at less than 50% even if the high blood pressure is treated by current medical drugs. Healthy diets are expected to not only prevent but also treat lifestyle-related diseases. Improvement of the dietary life, including low-salt diets, appropriate alcohol consumption, and calorie restriction, is important for the prevention of hypertension. In addition, green tea, which has been drunk on a daily basis in Japan and China since ancient times, possesses an antihypertensive effect, and it was revealed that its components with this effect are catechins. Many studies have been performed on the antihypertensive effects of foods. Therefore, functional foods and their ingredients, reported to possess antihypertensive effects in animal experiments and human clinical trials, are summarized in this review. Blood pressure might be controlled by improvement of the daily eating habits based on evidence regarding these functional foods, and a healthy longevity can be expected.

Herbal drugs against cardiovascular disease: traditional medicine and modern development

Herbal products have been used as conventional medicines for thousands of years, particularly in Eastern countries. Thousands of clinical and experimental investigations have focused on the effects and mechanisms-of-action of herbal medicine in the treatment of cardiovascular diseases (CVDs). Considering the history of clinical practice and the great potentials of herb medicine and/or its ingredients, a review on this topic would be helpful. This article discusses possible effects of herbal remedies in the prevention and treatment of CVDs. Crucially, we also summarize some underlying pharmacological mechanisms for herb products in cardiovascular regulations, which might provide interesting information for further understanding the effects of herbal medicines, and boost the prospect of new herbal products against CVDs.

Garlic for hypertension: A systematic review and meta-analysis of randomized controlled trials

BACKGROUND

In the past decade, garlic has become one of the most popular complementary therapies for blood pressure (BP) control used by hypertensive patients. Numerous clinical studies have focused on the BP-lowering effect of garlic, but results have been inconsistent. Overall, there is a dearth of information available to guide the clinical community on the efficacy of garlic in hypertensive patients.

AIM

To systematically review the medical literature to investigate the current evidence of garlic for the treatment of hypertension.

METHODS

PubMed, the Cochrane Library and EMBASE were searched for appropriate articles from their respective inceptions until August 2014. Randomized, placebo-controlled trials comparing garlic vs. a placebo in patients with hypertension were considered. Papers were independently reviewed by two reviewers and were analyzed using Cochrane software Revman 5.2.

RESULTS

A total of seven randomized, placebo-controlled trials were identified. Compared with the placebo, this meta-analysis revealed a significant lowering effect of garlic on both systolic BP (WMD: -6.71 mmHg; 95% CI: -12.44 to -0.99; P = 0.02) and diastolic BP (WMD: -4.79 mmHg; 95% CI: -6.60 to -2.99; P < 0.00001). No serious adverse events were reported in any of the trials.

CONCLUSION

The present review suggests that garlic is an effective and safe approach for hypertension. However, more rigorously designed randomized controlled trials focusing on primary endpoints with long-term follow-up are still warranted before garlic can be recommended to treat hypertensive patients.

Aqueous extract of dioscorea opposita thunb. normalizes the hypertension in 2K1C hypertensive rats

BACKGROUND

Dioscorea opposita Thunb. (Huai Shan Yao, DOT), a common staple food in China, has been used for more than 2000 years in traditional Chinese medicine (TCM) to treat different systemic diseases including hypertension. The objective of this study was to investigate the possible antihypertensive effects of the aqueous extract of (DOT) in renovascular hypertensive rats as well as the mechanism in reducing blood pressure.

METHODS

The two-kidney one-clip (2K1C) Goldblatt model of renovascular hypertension was used in Wistar rats. Rats with captopril, low-dose DOT and high-dose DOT treated 2K1C groups for 6 weeks. The blood pressure, cardiac mass index (heart weight/body weight), plasma level of angiotensin-II (Ang-II), endothelin-1(ET-1), superoxide dismutase (SOD) and malondialdehyde (MDA) were evaluated.

RESULTS

DOT significantly reduced mean systolic and diastolic blood pressure after treatment. DOT also significantly increased plasma SOD activity but decreased plasma MDA concentration. Renal function was improved with captopril and DOT. DOT reduced plasma Ang-II activity and plasma ET concentration. They couldalso significantly reduce the left ventricular hypertrophy and cardiac mass index.

CONCLUSIONS

Our results suggest that DOT may have an antihypertensive effect on hypertension by inhibit ET-converting enzyme and antioxidant activity, which warrant further exploration.

Perceived health properties of wild and cultivated food plants in local and popular traditions of Italy: A review

ETHNOPHARMACOLOGICAL RELEVANCE

Many wild and cultivated plants are rich in mineral elements and bioactive compounds and are consumed for health purposes. Studies have demonstrated the curative properties of many of these food plants. In this paper, we discuss the properties of several plants with potential health benefits that have previously received little attention.

AIM OF THE STUDY

This review provides an overview and critical discussion of food plants perceived by informants (emic view) as healthy or used as 'food medicine' in Italy. Pharmacological activity of these plants is explored, based upon published scientific research (etic view). Preparation methods, taste perception, toxicity and various potentialities of some food plants are also discussed.

MATERIALS AND METHODS

The present review includes literature available from 1877 to 2012. The information was collected from books, scientific papers, and abstracts that reported any plants used as food medicine in Italy. The perceived health properties were analyzed in the framework of recent international phytochemical and phytopharmacological literature.

RESULTS

A total of 67 edible wild plants and 18 cultivated vegetables, distributed into 20 families, were reported by informants (in literature). Several plants were highly cited (e.g., Taraxacum officinale Webb., Crepis vesicaria L., Allium cepa L., Allium sativum L.). The most frequent health properties attributed to edible plants by the informants were: laxative (22 species), diuretic (15), digestive (11), galactagogue (8), antitussive (cough) (8), hypotensive (7), tonic (7), sedative (7), hypoglycemic (6).

CONCLUSIONS

Some edible plants are promising for their potential health properties, such as Crepis vesicaria L., Sanguisorba minor Scop. and Sonchus oleraceus L. Several wild species were perceived by informants to maintain health but have never been studied from a phytochemical or pharmacological point of view: e.g., Asparagus albus L., Crepis leontodontoides All., Hyoseris radiata L. subsp. radiata, Phyteuma spicatum L.

Anti-hypertensive nutraceuticals and functional foods

Epidemiological studies have demonstrated that elevated blood pressure is one of the major risk factors for stroke and coronary heart disease (CHD). A close association between blood pressure and the incidence of cardiovascular diseases is well established if systolic/diastolic blood pressure is above 140/90 mmHg. In recent years, nutraceuticals and functional foods have attracted considerable interest as potential alternative therapies for treatment of hypertension, especially for prehypertensive patients, whose blood pressure is marginally or mildly high but not high enough to warrant the prescription of blood pressure-lowering medications. This review summarizes the findings of recent studies on the chemistry, production, application, efficacy, and mechanisms of popular blood pressure-lowering nutraceuticals and functional foods including the Dietary Approaches to Stop Hypertension (DASH) diet plan, L-arginine, chlorogenic acid, fermented milk, garlic, onion, tea, soybean, ginger, hawthorn, and fish oil.

Role of eicosanoids of the contralateral kidney in maintenance of two-kidney, one-clip renovascular hypertension in rats

OBJECTIVE

To elucidate the role of the eicosanoids prostaglandin E(2) (PGE(2)), 6-keto-prostaglandin F(1a) (PGF(1a)) and thromboxane B(2) (TXB(2)) in the maintenance of two-kidney, one-clip renovascular hypertension in rats.

MATERIAL AND METHODS

The right renal artery was constricted by a silver clip in 63 male Sprague-Dawley rats to induce hypertension, while a sham operation was performed in 17 control rats. Six months after the induction of hypertension, nephrectomy of the clipped kidney was performed. Nephrectomy was followed by a period of high sodium intake. Blood pressure and eicosanoid excretion were measured before and after nephrectomy of the clipped kidney, as well as during high sodium intake.

RESULTS

During the chronic phase of Goldblatt hypertension, the amount of vasoconstrictive TXB(2) excreted by the contralateral kidney increased compared to that in the controls, whereas PGE(2) excretion was unaffected. Eicosanoid excretion before and after removal of the clipped kidney did not differ between post-Goldblatt hypertensive and post-Goldblatt normotensive animals. During the period of high sodium intake, PGE(2) excretion increased only in control rats, being unaltered in Goldblatt hypertensive rats.

CONCLUSIONS

In the chronic phase of two-kidney, one-clip renovascular hypertension, the contralateral kidney of post-Goldblatt hypertensive and post-Goldblatt normotensive rats excretes more vasoconstrictive thromboxane in comparison to controls, whereas excretion of vasodilatory prostaglandin is not elevated. However, increased TXB(2) excretion and the absence of an increase in PGE(2) excretion from the contralateral kidney do not appear to be important for the maintenance of high blood pressure in this model of renovascular hypertension.

Nitric oxide mediates the blood-pressure lowering effect of garlic in the rat two-kidney, one-clip model of hypertension

Garlic reduces blood pressure (BP) in two-kidney, one-clip (2K-1C) rats, and enhances nitric oxide (NO) synthesis in in vivo and in vitro experiments. NO is an important modulator of BP in the 2K-1C model. This study investigated the role of NO in the BP-lowering effect of garlic in the 2K-1C model. BP readings (mm Hg) were obtained from 2K-1C rats in 4 groups treated intraperitoneally for 2 wk with either normal saline (NS), garlic, L-nitroarginine-methylester (L-NAME), or L-NAME+garlic (n=4x5). BP was determined using the tail-cuff method and compared with data of 4 similarly treated groups of normal (unclipped) rats (NRs). The BP readings of NR groups were 120+/-3 mm Hg for the NS-treated group, 120+/-2 mm Hg for the garlic-treated group, 167+/-3 mm Hg for the L-NAME treated group (higher than NS or garlic, P<0.001) and 128+/-5 mm Hg for the garlic+L-NAME-treated group (lower than L-NAME, P<0.001). The BP readings of 2K-1C rat groups were: for the NS group, 169+/-6 mm Hg (higher than NRs, P<0.001); for the garlic group, 116+/-7 mm Hg (lower than NS, P<0.001); for the L-NAME group: 184+/-8 mm Hg (higher than garlic, P<0.001), and for the L-NAME+garlic group: 130+/-6 mm Hg (lower than garlic or NS, P<0.001). The data show that L-NAME increases the BP of both NRs and 2K-1C rats, with the rise more evident in the NRs (39 vs. 9%, respectively). Garlic counteracts the hypertensive effect of L-NAME in NRs as well as 2K-1C rats. We conclude that the BP-lowering effect of garlic in the rat 2K-1C model may be partly mediated through the NO pathway.

Mechanism of garlic (Allium sativum) induced reduction of hypertension in 2K-1C rats: a possible mediation of Na/H exchanger isoform-1

Garlic causes reduction in blood pressure (BP), however the role of Na/H exchanger (NHE) which mediates hypertension and related tissue-damage is poorly understood. In this study the effect of an established dose of raw garlic extract was investigated on the expression of NHE-1 and -3 and sodium pump activity in a 2K-1C model of hypertension in rats. 2K-1C animals showed high BP, increased serum concentration of PGE2 and TxB2, hypertrophy of the unclipped kidneys, but not in the clipped kidneys In addition, NHE-1 and NHE-3 isoforms were increased in both the 2K-1C kidneys, whereas alpha-actin was increased in the clipped but not in unclipped kidneys. Sodium pump activity was decreased in the clipped kidneys, but remained unchanged in the unclipped kidneys. Garlic treatment reduced the induction of NHE-1 only in the unclipped 2K-1C kidneys, whereas garlic treatment increased the sodium pump activity in both the 2K-1C kidneys. These findings demonstrate that the antihypertensive action of garlic is associated with a reversal of NHE-1 induction in the unclipped kidneys. Induction of NHE isoforms together with a reduced sodium pump activity might cause necrosis in the 2K-1C clipped kidneys due to cellular retention of Na+. On the other hand, activation of sodium pump by garlic extract in the kidneys should reduce intracellular Na+ concentration and normalize BP. These findings signify the use of garlic in the treatment of hypertension.

Effect of garlic on cardiovascular disorders: a review

Garlic and its preparations have been widely recognized as agents for prevention and treatment of cardiovascular and other metabolic diseases, atherosclerosis, hyperlipidemia, thrombosis, hypertension and diabetes. Effectiveness of garlic in cardiovascular diseases was more encouraging in experimental studies, which prompted several clinical trials. Though many clinical trials showed a positive effect of garlic on almost all cardiovascular conditions mentioned above, however a number of negative studies have recently cast doubt on the efficacy of garlic specially its cholesterol lowering effect of garlic. It is a great challenge for scientists all over the world to make a proper use of garlic and enjoy its maximum beneficial effect as it is the cheapest way to prevent cardiovascular disease. This review has attempted to make a bridge the gap between experimental and clinical study and to discuss the possible mechanisms of such therapeutic actions of garlic.