Antihypertensive effects of crude extracts from leaves of Echinodorus grandiflorus

Antiatherosclerotic Properties of Echinodorus grandiflorus (Cham. & Schltdl.) Micheli: From Antioxidant and Lipid-Lowering Effects to an Anti-Inflammatory Role

Echinodorus grandiflorus is an important medicinal plant species that is native to South America. Despite extensive popular usage as a hypolipidemic drug, its effects as an atheroprotective agent remain unknown. The aim of this study was to evaluate the effects of an ethanol-soluble fraction that was obtained from E. grandiflorus (ESEG) leaves against the development of atherosclerosis in rabbits. Male rabbits received a diet that was supplemented with 1% cholesterol (cholesterol-rich diet [CRD]) for 60 days. After 30 days of the CRD, the animals were divided into five groups (n = 6) and treated with ESEG (10, 30, and 100 mg/kg), simvastatin (2.5 mg/kg), or vehicle once daily for 30 days. The negative control group was fed a cholesterol-free diet and treated orally with vehicle. At the end of 60 days, serum lipids, oxidized low-density lipoprotein, thiobarbituric acid reactive substances, nitrotyrosine, and serum interleukin 1 beta (IL-1β), IL-6, soluble intercellular adhesion molecule-1 (sICAM-1), and soluble vascular cell adhesion molecule-1 (sVCAM-1) levels were determined. Samples from the aortic arch and thoracic segment were also collected to investigate the tissue antioxidant defense system and perform histopathological analysis. Oral ESEG administration significantly reduced serum lipid levels in CRD-fed rabbits. This treatment also modulated the arterial antioxidant defense system by reducing lipid and protein oxidation. Similarly, serum IL-1β, IL-6, sICAM-1, and sVCAM-1 levels significantly decreased, accompanied by a reduction of atherosclerotic lesions in all arterial branches. These findings suggest that ESEG may be a new herbal medicine that can be directly applied for the treatment and prevention of atherosclerotic disease.

Endothelium-Dependent Effects of Echinodorus grandiflorus (Cham. & Schltdl.) Micheli Mediated by M3-Muscarinic and B2-Bradykininergic Receptors on Peripheral Vascular Resistance and Its Modulatory Effects on K+ Channels in Mesenteric Vascular Beds

This work provides the first demonstration that ethanolic extract (EEEG) obtained from Echinodorus grandiflorus leaves (EEEG) and its butanolic fraction (ButFr) has important vasodilatory effects on isolated mesenteric vascular beds (MVBs). First, the EEEG was obtained and a liquid-liquid fractionation was performed. EEEG and its resulting fractions were analyzed by high-performance liquid chromatography. Then, the vasodilatory effects of EEEG and their respective fractions were evaluated. Finally, the molecular mechanisms involved in the vasodilator responses of the EEEG and ButFr were also investigated. EEEG vasodilator response was estimated at ~11 and 18 mm Hg at doses of 0.1 and 0.3 mg, respectively. Moreover, it was found that ButFr was able to induce an expressive dose-dependent vasodilator response in MVBs. The PP reduction values for doses of 0.1 and 0.3 mg were ~10 and 28 mm Hg, respectively. Endothelium removal or inhibition of nitric oxide and prostaglandin synthase (by L-NAME plus indomethacin) inhibited the vasodilatory effects induced by ButFr or EEEG. The peak effect of ButFr and EEEG doses (0.1 and 0.3 mg) was decreased by ~100% (p < 0.001). The association of atropine plus HOE-140 fully inhibited EEEG and ButFr-induced vasodilation (p < 0.001). Moreover, perfusion with nutritive solution containing 40 mM KCl or previous treatment with tetraethylammonium completely blocked vasodilation induced by ButFr (p < 0.001). This study showed that EEEG and its ButFr have important vasodilatory effects by endothelial M3-muscarinic and B2-bradykininergic receptors inducing nitric oxide and prostacyclin release followed by K+ channels activation in the vascular smooth muscle.

The Confrontation between Ethnopharmacology and Pharmacological Tests of Medicinal Plants Associated with Mental and Neurological Disorders

For neurological disorders, pharmacological tests have shown promising results in the reduction of side effects when using plants with known therapeutic effects in the treatment of some types of dementia. Therefore, the goals of this study are to gather data about the major medicinal plants used in the nervous system as described in ethnopharmacological surveys from South America and Brazil and to compare this data with the results from pharmacological tests on the active principles of those same plants found in the scientific literature. After collecting the data about each plant, their respective popular indication was compared with the results found through pharmacological tests. The discrepancy rate between the effects observed by ethnopharmacological and pharmacological methods in this study is greater than 50%. In conclusion, despite the importance of ethnopharmacological data, it is important to make comparisons with pharmacological tests for the same plants, since the pharmacological studies, although few, have shown a high rate of discrepancy in the results.

Alterations of haemodynamic parameters in spontaneously hypertensive rats by Aristolochia ringens Vahl. (Aristolochiaceae)

Aristolochia ringens Vahl. (Aristolochiaceae (AR); 馬兜鈴 mǎ dōu líng) is used traditionally in Nigeria for the management of various disorders including oedema. Preliminary investigation revealed its modulatory effect on the cardiovascular system. This study was aimed at investigating the effect of the aqueous root extract of A. ringens (AR) on haemodynamic parameters of spontaneously hypertensive rats (SHRs). The effect of oral subacute (21 days) and intravenous acute exposure of SHRs to the extract were assessed using tail cuff and carotid artery canulation methods respectively. In the latter, the effect of chloroform, butanol and aqueous fractions of AR were also evaluated. The extract significantly reduced systolic and diastolic blood pressures in SHRs, with peak reductions of 20.3% and 26.7% respectively at 50 mg/kg by the 21st day of oral subacute exposure. Upon intravenous exposure, AR (50 mg/kg) reduced systolic and diastolic blood pressure by as much as 53.4 ± 2.2 and 49.2 ± 2.8 mmHg respectively. A dose-dependent reduction in heart rate, significant at 25 and 50 mg/kg was also observed. Hexamethonium (20 mg/kg) and atropine (1 mg/kg) inhibited the extract's reduction of systolic blood pressure, diastolic blood pressure and heart rate significantly. The extract's butanol fraction produced the greatest systolic and diastolic blood pressures reduction of 67.0 ± 3.8 and 68.4 mmHg respectively at 25 mg/kg and heart rate reduction of 40 ± 7 beats per minute at 50 mg/kg. HPLC analysis revealed the presence of 4-hydroxybenzoic acid and quercetin in AR. The extract's alterations of haemodynamic parameters in this study show that it has hypotensive effect on spontaneously hypertensive rats.

Echinodorus grandiflorus: Ethnobotanical, phytochemical and pharmacological overview of a medicinal plant used in Brazil

Echinodorus grandiflorus (Cham. & Schltdl.) Micheli is a native Brazilian species used in traditional practices for the treatment of several conditions such as inflammatory diseases, arthritis and hypertension. Through a systematic review of the accumulated knowledge about the species E. grandiflorus, the botanical, phytochemistry, ethnobotanical and pharmacological properties of this medicinal plant demonstrates its potential to naturally provide anti-inflammatory and anti-oxidant with a special emphasis on anti-hypertensive and cardioprotective effects. The body of literature reports that the chemical composition of crude E. grandiflorus extracts are notably composed of diterpenoids and flavonoids metabolites. Pharmacological studies have shown that oral treatments using the hydroalcoholic extracts of leaves from this plant has a significant anti-inflammatory, anti-hypertensive, diuretic and cardioprotective effects in rats with no toxicity. The holistic activities of complex extracts are corroborated by the individuals mechanisms of action, as well as, synergistic benefits attributed to the isolated chemical major constituents in this species. In light of the serious health concerns ascribed, it is important to investigate medicinal plant species with histories of traditional use for circulatory problems to meet the growing demands by scientifically validating their use and safety.

Involvement of bradykinin B2 and muscarinic receptors in the prolonged diuretic and antihypertensive properties of Echinodorus grandiflorus (Cham. & Schltdl.) Micheli

BACKGROUND

Although Echinodorus grandiflorus (Cham. & Schltr.) Michel are used in Brazilian folk medicine as a diuretic drug, to date, no study has evaluated the mechanisms involved in this activity after prolonged administration in rats.

AIM OF THE STUDY

Evaluate the possible mechanisms involved in the prolonged diuretic activity of ethanol soluble fraction obtained from Echinodorus grandiflorus (ES-EG) and to assess its relationship with hypotensive and antihypertensive activity using normotensive rats and those with renovascular hypertension (2K1C).

METHODS

The diuretic effects of ES-EG (30-300 mg/kg; p.o.) were compared with hydrochlorothiazide in a repeated-dose treatment for 7 days. The urinary volume and sodium, potassium, chloride, bicarbonate contents, conductivity, pH and density were estimated in sample collected in 24 h for 7 days. Plasma sodium, potassium, total protein, urea, creatinine, aldosterone, vasopressin, nitrite, acetylcholinesterase concentration and angiotensin converting enzyme (ACE) activity were measured in samples collected at the end of the experimental period (seventh day). Using pharmacological antagonists or inhibitors, the involvement of bradykinin, prostaglandin, acetylcholine and nitric oxide (NO) in ES-EG-induced diuresis was determined. In addition, activities of erythrocytary carbonic anhydrase and renal Na+/K+/ATPase were evaluated in vitro.

RESULTS

ES-EG increased diuresis similarly to hydrochlorothiazide and also presented HCO3-sparing effects and increased serum nitrite levels. Moreover, the intraduodenal administration of ES-EG induces significant hypotensive and antihypertensive effects in 2K1C rats. Previous treatment with HOE-140, indometacin and atropine fully avoided the diuretic effect of ES-EG, and including L-NAME pre-administration, it prevented the hypotensive and hypertensive activity induced by ES-EG. In addition, the association between HOE-140 and atropine or indometacin and L-NAME fully inhibited the hypotensive and antihypertensive effects of ES-EG. The 7-day treatment with ES-EG resulted in increased plasma nitrite levels. All other parameters were not affected by treatment with ES-EG.

CONCLUSIONS

Our results suggest that the mechanisms through which Echinodorus grandiflorus extracts induce prolonged diuresis and reduce blood pressure in normotensive and 2K1C rats are mainly related to activation of muscarinic and bradykinin receptors with direct effects on prostaglandins and nitric oxide pathways.

Inhibition of Angiotensin Converting Enzyme, Angiotensin II Receptor Blocking, and Blood Pressure Lowering Bioactivity across Plant Families

Hypertension is a major risk factor for coronary heart disease, kidney disease, and stroke. Interest in medicinal or nutraceutical plant bioactives to reduce hypertension has increased dramatically. The main biological regulation of mammalian blood pressure is via the renin-angiotensin-aldosterone system. The key enzyme is angiotensin converting enzyme (ACE) that converts angiotensin I into the powerful vasoconstrictor, angiotensin II. Angiotensin II binds to its receptors (AT1) on smooth muscle cells of the arteriole vasculature causing vasoconstriction and elevation of blood pressure. This review focuses on the in vitro and in vivo reports of plant-derived extracts that inhibit ACE activity, block angiotensin II receptor binding and demonstrate hypotensive activity in animal or human studies. We describe 74 families of plants that exhibited significant ACE inhibitory activity and 16 plant families with potential AT1 receptor blocking activity, according to in vitro studies. From 43 plant families including some of those with in vitro bioactivity, the extracts from 73 plant species lowered blood pressure in various normotensive or hypertensive in vivo models by the oral route. Of these, 19 species from 15 families lowered human BP when administered orally. Some of the active plant extracts, isolated bioactives and BP-lowering mechanisms are discussed.

Anti-Hypertensive Herbs and Their Mechanisms of Action: Part II

Traditional medicine has a history extending back to thousands of years, and during the intervening time, man has identified the healing properties of a very broad range of plants. Globally, the use of herbal therapies to treat and manage cardiovascular disease (CVD) is on the rise. This is the second part of our comprehensive review where we discuss the mechanisms of plants and herbs used for the treatment and management of high blood pressure. Similar to the first part, PubMed and ScienceDirect databases were utilized, and the following keywords and phrases were used as inclusion criteria: hypertension, high blood pressure, herbal medicine, complementary and alternative medicine, endothelial cells, nitric oxide (NO), vascular smooth muscle cell (VSMC) proliferation, hydrogen sulfide, nuclear factor kappa-B (NF-κB), oxidative stress, and epigenetics/epigenomics. Each of the aforementioned keywords was co-joined with plant or herb in question, and where possible with its constituent molecule(s). This part deals in particular with plants that are used, albeit less frequently, for the treatment and management of hypertension. We then discuss the interplay between herbs/prescription drugs and herbs/epigenetics in the context of this disease. The review then concludes with a recommendation for more rigorous, well-developed clinical trials to concretely determine the beneficial impact of herbs and plants on hypertension and a disease-free living.

Ethnopharmacological investigation of the diuretic and hemodynamic properties of native species of the Brazilian biodiversity

ETHNOPHARMACOLOGICAL RELEVANCE

Although Echinodorus grandiflorus, Cuphea carthagenensis, and Phyllanthus tenellus infusions are used in Brazilian folk medicine due to their possible diuretic effect, none of these species was critically investigated as a diuretic drug. So, the aim of this study was to evaluate the possible acute diuretic activity of ethanol soluble fractions (ES) obtained from these species and assess the relationship between renal cortical blood flow and their antioxidant and hypotensive activity using normotensive Wistar rats.

MATERIAL AND METHODS

The preparation obtained from E. grandiflorus (ES-EG), C. carthagenensis (ES-CC), and P. tenellus (ES-PT) infusions was orally administered in a single dose to rats. Urine excretion rate, pH, density, conductivity and Na(+), K(+), Cl(-) and HCO3(-) contents were measured in the urine of saline-loaded animals. Concentration of electrolytes, total protein, urea, creatinine, and angiotensin converting enzyme (ACE) activity were evaluated in collected serum. The involvement of the renal cortical blood flow and antioxidative activity in the hypotensive and diuretic effects was also determined.

RESULTS

Water and Na(+), Cl(-) and Na(+) excretion rates were significantly increased by ES-EG, while urinary bicarbonate excretion was reduced. Moreover, ES obtained from E. grandiflorus was able to significantly increase renal blood flow and reduce mean arterial pressure and oxidative stress in "in vitro" and "in vivo" models. All other parameters evaluated were not affected by any treatment.

CONCLUSION

The results presented here shown that the ES-EG obtained from E. grandiflorus leaves shown a significant diuretic and hypotensive activity and suggest that these effects could be related with an important renal and systemic vasodilator effect. In addition, it was shown for the first time that the pharmacological effects of ES obtained from P. tenellus and C. carthagenensis do not support its popular use as a diuretic agent.

Loranthus ferrugineus: a Mistletoe from Traditional Uses to Laboratory Bench

Objectives:

Loranthus ferrugineus (L. ferrugineus) from Loranthaceae, a mistletoe, is a medicinal herb used for a variety of human ailments. Traditionally, decoctions of this parasitic shrub have been mainly used to treat high blood pressure (BP) and gastrointestinal complaints; usage which is supported by experimental based pharmacological investigations. Nonetheless, there is still limited data available evaluating this plant’s traditions, and few studies have been scientifically translated toward evidence based phytomedicine. We therefore provide a concise review of the currently available L. ferrugineus literature and discuss potential directions for future areas of investigation.

Methods:

We surveyed available literature covering ethnopharmacological usage of L. ferrugineus and discussed relevant findings, including important future directions and shortcomings for the medicinal values of this parasitic shrub.

Results:

Evidence based pharmacological approaches significantly covered the medicinal application of L. ferrugineus for hypertension and gastrointestinal complaint management, with a particular focus on the active hydrophilic extract of this herb.

Conclusion:

Understanding the sites of action of this plant and its beneficial effects will provide justification for its use in old traditional treatments, and potentially lead to the development of therapies. Other medicinal applicative areas of this parasitic shrub, such as wound healing, gerontological effects, and antiviral and anticancer activities, are yet to be researched.

In vitro antioxidant capacity of tea of Echinodorus grandiforus, “leather hat,” in Wistar rat liver

Oxidative stress has been considered as one of the factors responsible for hepatic diseases, which sometimes require new ways of treatment. The present study aimed to evaluate the in vitro antioxidant capacity of the tea of Echinodorus grandiforus (“leather hat” plant) in rat liver. Different preparations of tea were evaluated for phenolic composition, antioxidant activity by DPPH assay and ability to inhibit lipid peroxidation induced by copper sulfate. The antioxidant activity was assessed in liver tissue treated with sodium azide in the presence or absence of tea by assays for lipid peroxidation (TBARS), protein oxidation (carbonyl) and the antioxidant enzymes catalase (CAT) and superoxide dismutase (SOD). The results show that different preparations of tea are important sources of polyphenols and contain theobromine, catechin and vitexin. Furthermore, the results indicate that this tea exhibits an antioxidant activity by its ability to scavenge DPPH radical. Different preparations of tea prevented damage to lipids and proteins induced by sodium azide, as well as assisting in restoring CAT and SOD activities. Thus, it can be seen that E. grandiforus tea had antioxidant activity in serum and liver being able to prevent oxidative damages generated by sodium azide.

Angiotensin Converting Enzyme Inhibition Activity of Fennel and Coriander Oils from India

Foeniculum vulgare Mill and Coriandrum sativum L. are very popular spices in Indian kitchens. The present study was an attempt to evaluate the angiotensin converting enzyme (ACE) inhibition and antioxidant activity of the standardized oils of F. vulgare and C. sativum by an UV method using hippuryl-L-histidyl-L-leucine (HHL) as substrate. Standardization of the oils and identification of the chemical-markers (linalool and anethole) present in them was performed through HPLC and GC-MS. Coriander oil showed the higher ACE inhibition with an IC50 value of 34.8 ± 2.3 μg/mL, than fennel oil with an IC50 value of 40.7 ± 3.5 μg/mL. Both oils showed strong DPPH radical scavenging activity. This finding suggests that coriander and fennel oils can be potential leads for the management of hypertension as an ACE inhibitor.

The contributions of muscarinic receptors and changes in plasma aldosterone levels to the anti-hypertensive effect of Tulbaghia violacea

BACKGROUND

Tulbaghia violacea Harv. (Alliaceae) is used to treat various ailments, including hypertension (HTN) in South Africa. This study aims to evaluate the contributions of muscarinic receptors and changes in plasma aldosterone levels to its anti-hypertensive effect.

METHODS

In the acute experiments, methanol leaf extracts (MLE) of T. violacea (30-120 mg/kg), muscarine (0.16 -10 μg/kg), and atropine (0.02 - 20.48 mg/kg), and/or the vehicle (dimethylsulfoxide (DMSO) and normal saline (NS)) were respectively and randomly administered intravenously in a group of spontaneously hypertensive (SHR) weighing 300 to 350 g and aged less than 5 months. Subsequently, T. violacea (60 mg/kg) or muscarine (2.5 μg/kg) was infused into eight SHRs, 20 min after atropine (5.12 mg/kg) pre-treatment. In the chronic (21 days) experiments, the SHRs were randomly divided into three groups, and given the vehicle (0.2 ml/day of DMSO and NS), T. violacea (60 mg/kg/day) and captopril (10 mg/kg/day) respectively into the peritoneum, to investigate their effects on blood pressure (BP), heart rate (HR), and plasma aldosterone levels. Systolic BP and HR were measured using tail-cuff plethysmography during the intervention. BP and HR were measured via a pressure transducer connecting the femoral artery and the Powerlab at the end of each intervention in the acute experiment; and on day 22 in the chronic experiment.

RESULTS

In the acute experiments, T. violacea, muscarine, and atropine significantly (p < 0.05) reduced BP dose-dependently. T. violacea and muscarine produced dose-dependent decreases in HR, while the effect of atropine on HR varied. After atropine pre-treatment, dose-dependent increases in BP and HR were observed with T. violacea; while the BP and HR effects of muscarine were nullified. In the chronic experiments, the T. violacea-treated and captropril-treated groups had signicantly lower levels of aldosterone in plasma when compared to vehicle-treated group. Compared to the vehicle-treated group, significant reduction in BP was only seen in the captopril-treated group; while no difference in HR was observed among the groups.

CONCLUSION

The results obtained in this study suggest that stimulation of the muscarinic receptors and a reduction in plasma aldosterone levels contribute to the anti-hypertesive effect of T. violacea.

Possible mechanisms of action of the hypotensive effect of Annona muricata (soursop) in normotensive Sprague-Dawley rats

CONTEXT

Annona muricata Linn (Annonaceae) (soursop) is a food plant reported to have antihypertensive properties.

OBJECTIVE

We investigated the blood pressure reducing effect of its aqueous leaf extract and the possible mechanisms that may be responsible.

METHODS

Intravenous administration of an aqueous leaf extract (9.17-48.5 mg/kg) of A. muricata on the mean arterial pressure and heart rate were recorded invasively on anaesthetized, normotensive Sprague-Dawley rats. Contractile responses of rat aortic rings to the extract (0.5-4.0 mg/mL) were studied using standard organ bath techniques.

RESULTS

A. muricata (9.17-48.5 mg/kg) caused significant (p < 0.05) dose-dependent reduction in blood pressure without affecting the heart rates. The hypotensive effects were unaffected by atropine (2 mg/kg), mepyramine (5 mg/kg), propranolol (1 mg/kg) and L-NAME (5 mg/kg). A. muricata leaf aqueous extract significantly (p < 0.05) relaxed phenylephrine (10(-9)-10(-4) M) and 80 mM KCl induced contractions in endothelium intact and denuded aortic rings; and caused a significant (p < 0.05) rightward shift of the Ca(2+) dose response curves in Ca(2+)-free Kreb's solution containing 0.1 mM EGTA.

CONCLUSIONS

The hypotensive effects of A. muricata are not mediated through muscarinic, histaminergic, adrenergic and nitric oxide pathways, but through peripheral mechanisms involving antagonism of Ca(2+).

Effects of aqueous extract of Echinodorus grandiflorus on the immune response in ovalbumin-induced pulmonary allergy

BACKGROUND

Asthma is a disease characterized by intermittent obstruction of the airways and chronic inflammation that affects approximately 300 million people worldwide. The immune response in asthma is predominantly T(H)2, with high levels of total and allergen-specific IgE and bronchial eosinophilia. Asthma treatment is aimed at controlling the disease, and the drugs used currently have systemic adverse effects and generally are not effective in difficult-to-control cases.

OBJECTIVE

To investigate the effect of aqueous extract of Echinodorus grandiflorus, a plant used in folk medicine for its diuretic and anti-inflammatory properties, in a model of pulmonary allergy.

METHODS

BALB/c mice were intraperitoneally sensitized and nasally challenged with ovalbumin. Aqueous extract and dexamethasone treatments (0.1 mL/d per mouse) were initiated on day 32 and concluded on day 40. Eight hours after the last challenge evaluations, of serum, bronchoalveolar lavage, and lung tissue were performed.

RESULTS

Oral treatment with the extract markedly reduced the number of total cells and eosinophils in bronchoalveolar lavage. The eosinophil peroxidase activity in lung tissue, the levels of ovalbumin-specific IgE in serum, the levels of CCL11, and the gene expression of interleukin 4 and interleukin 13 in lung tissue were also lower after treatment.

CONCLUSIONS

These results suggest that the aqueous extract of E grandiflorus is able to modulate allergic pulmonary inflammation and may be useful as a potential therapeutic agent for asthma.