Hypotensive effect of aqueous extract of Averrhoa carambola L. (Oxalidaceae) in rats: an in vivo and in vitro approach

Averrhoa carambola Leaf Extract Induces Apoptosis-Like Death with Increased ROS Generation in Leishmania donovani

PURPOSE

The parasitic disease leishmaniasis is responsible for high mortality and morbidity rates worldwide. The visceral form is the most severe form of leishmaniasis (or leishmaniosis), which is caused predominantly by Leishmania donovani. Currently, clinically recommended antileishmanial drugs are not convenient because of several medical complications and resistance issues. Phytocompounds are the best candidates in this regard. The present study aimed to evaluate the antileishmanial activity of Averrhoa carambola leaf extract.

METHODS

The antipromastigote activity and cytotoxicity were assessed using the MTT assay. Morphological distortions were determined using phase contrast microscopy and scanning electron microscopy (SEM). Reactive oxygen species (ROS) production, nonprotein thiol depletion and apoptotic death in promastigotes were determined via flow cytometry. UV-visible spectroscopy and energy dispersive X-ray (EDX) spectroscopy was performed for elemental analysis. Fourier-transform infrared spectroscopy (FTIR) and liquid chromatography‒mass spectrometry (LCMS) were used to characterize the phytocomponent(s) present in the extract.

RESULTS

The chloroform extract of Averrhoa carambola leaf (ACCEX) (IC50 = 50.76 ± 1.7 µg/mL) exhibited the highest activity, followed by the ethyl acetate, hexane, and methanol extracts. ACCEX has also exhibited lower toxicity towards host macrophages. ACCEX also induced morphological distortions in promastigotes, with significant generation of ROS and the concomitant apoptosis initiation followed by a decrease in the nonprotein thiol level. The major phytometabolites present in ACCEX were identified from the National Institute of Standards and Technology (NIST) database and from a literature review.

CONCLUSIONS

This study suggested that Averrhoa carambola leaf extracts are rich in some classes of biologically active phytocompounds and exhibit good antileishmanial activity.

Traditional Uses, Phytochemical Constituents and Pharmacological Properties of Averrhoa carambola L.: A Review

Averrhoa carambola L. (star fruit) is an edible fruit that is extensively cultivated in southern China, Southeast Asia, India, and northern South America. It has a sweet and juicy taste and is frequently used in fruit salads and fruit platters, as a garnish in cocktail drinks and beverages, or squeezed into juice and served as a beverage. Traditionally, it has been used for treating diabetes and diabetic nephropathy, arthralgia, vomiting, lithangiuria, coughing, hangovers, and chronic paroxysmal headache for thousands of years. Currently, approximately 132 compounds have been isolated from A. carambola. Among them, flavonoids, benzoquinone, and their glycosides have been considered as biologically active substances, which are responsible for various biological activities. Pharmacological studies have revealed that crude extracts or monomeric compounds from A. carambola exhibit multiple bioactivities, such as anti-oxidant, anti-hyperglycemic, anti-obesity, anti-hyperlipidemic, anti-tumor, anti-inflammatory, hepatoprotective, cardioprotective, anti-hypertensive, neuroprotective, and others. Thus, A. carambola is a valuable treatment in Chinese medicine with therapeutic potential for multiple diseases, especially diabetes and diabetes-related diseases. Even though it is a very promising candidate in the development of functional food and the pharmaceutical industry, reports on its bioactivities have only been conducted in vivo and in vitro and there is a gap in research regarding clinical settings and safety. This review therefore provides a comprehensive and systematic overview of current progress on botany, ethnopharmacology, phytochemistry, pharmacology, and toxicity of A. carambola, providing a valuable reference for further developments and applications of A. carambola in the pharmaceutical industry and functional food.

Plants Used as Antihypertensive

Hypertension is a critical health problem and worse other cardiovascular diseases. It is mainly of two types: Primary or essential hypertension and Secondary hypertension. Hypertension is the primary possibility feature for coronary heart disease, stroke and renal vascular disease. Herbal medicines have been used for millions of years for the management and treatment of hypertension with minimum side effects. Over aim to write this review is to collect information on the anti-hypertensive effects of natural herbs in animal studies and human involvement as well as to recapitulate the underlying mechanisms, from the bottom of cell culture and ex-vivo tissue data. According to WHO, natural herbs/shrubs are widely used in increasing order to treat almost all the ailments of the human body. Plants are the regular industrial units for the invention of chemical constituents, they used as immunity booster to enhance the natural capacity of the body to fight against different health problems as well as herbal medicines and food products also. Eighty percent population of the world (around 5.6 billion people) consume medicines from natural plants for major health concerns. This review provides a bird's eye analysis primarily on the traditional utilization, phytochemical constituents and pharmacological values of medicinal herbs used to normalize hypertension i.e. Hibiscus sabdariffa, Allium sativum, Andrographis paniculata, Apium graveolens, Bidenspilosa, Camellia sinensis, Coptis chinensis, Coriandrum sativum, Crataegus spp., Crocus sativus, Cymbopogon citrates, Nigella sativa, Panax ginseng,Salviaemiltiorrhizae, Zingiber officinale, Tribulus terrestris, Rauwolfiaserpentina, Terminalia arjuna etc.

Nutritional and medicinal properties of Star fruit (Averrhoa carambola): A review

Star fruit (Averrhoa carambola), a popular fruit in many parts of the world, is considered to have many beneficial nutritional and medicinal effects. However, harmful nephrotoxic and neurotoxic effects have also been described. In this review, we have discussed the reported beneficial effects of star fruit, explored the potential mechanisms for such beneficial effects, and outline factors that may affect the safe level of consumption. The beneficial effects include the following: antioxidant (mediated via L-ascorbic acid, epicatechin, and gallic acid), hypoglycemic (mediated via high fiber levels and 2-dodecyl-6-methoxycyclohexa-2,5-diene-1,4-dione), hypotensive (mediated via apigenin), hypocholesterolemic (mediated via micronized fiber), anti-inflammatory, anti-infective, antitumor effects, and immune-boosting effects. The presence of chronic kidney disease, gastroenteropathies, chronic pancreatitis, dehydration, consumption on an empty stomach, and higher concentration of oxalate in fruit/juice consumed predisposes to toxicity. The level of ingestion at which the beneficial effects transition to nephrotoxicity and neurotoxicity is still to be accurately ascertained. Furthermore, the relationship between the amount of star fruit ingested and the severity of toxicity is not certain and warrants further study.

In vivo the antioxidative extract of Averrhoa carambola Linn. leaves induced apoptosis in Ehrilch ascites carcinoma by modulating p53 expression

This study was designed to evaluate the antioxidant activity of methanol extract of Averrhoa carambolla Linn. leaves (MELA) using DPPH· and ABTS·+ free radical scavenging assays whereas its antineoplastic effect against Ehrlich ascites carcinoma (EAC) was assed using viable cell count, life span, body weight gain and hematological parameters of experimental mice. Results showed that rich phenolic and flavonoid content of MELA had moderate dose dependent free radical scavenging activity (IC50: 62.0 μg/mL for DPPH· and 6.0 μg/mL for ABTS·+). In vivo antineoplastic assay, MELA significantly (P < 0.05) decreased viable cells and body weight gain, increased the survival time and restored altered hematological profiles of cancer cell bearing mice. Fluorescence microscopic view of EAC cells derived from MELA-treated group showed apoptotic characteristics and this observation was also supported by overexpression of pro-apoptotic genes coding p53 and Bax proteins in treated cancer cells. The anti-apoptotic genes coding Bcl-2 protein was also absent in treated EAC cells as compared with the control. Moreover, phytochemical profiles of MELA as identified by GC/MS analysis are also consistent with its activities.

Dihydrochalcone C-glycosides from Averrhoa carambola leaves

Ten undescribed dihydrochalcone C-glycosides, carambolasides R1‒R3, S1, S2, T1‒T3, 3-hydroxycarambolaside T1, and 3-hydroxycarambolaside P were isolated along with carambolasides I and P from the leaves of Averrhoa carambola L. (Oxalidaceae). Their structures were determined by spectroscopic and chemical methods. Among them, carambolasides P, T1, T2, and I with contents of 22.78, 14.39, 4.93, and 1.87 mg g^-1 dry wt., respectively, were shown to be abundant in the leaves by HPLC analysis. All the compounds showed more potent ABTS radical cation scavenging activity than l-ascorbic acid. 3-Hydroxycarambolaside T1 and 3-hydroxycarambolaside P also demonstrated moderate DPPH radical scavenging activity. Further, carambolaside R3, 3-hydroxycarambolaside T1, and 3-hydroxycarambolaside P exhibited weak in vitro porcine pancreatic lipase inhibitory activity.

El-Sayed N, A. El-Toumy S, Abdou Mohamed D, Abdel Aziz Z, Ehrlich A, A. Farag M. Nutrient and Sensory Metabolites Profiling of Averrhoa Carambola L. (Starfruit) in the Context of Its Origin and Ripening Stage by GC/MS and Chemometric Analysis

Averrhoa carambola L. is a tropical tree with edible fruit that grows at different climatic conditions. Despite its nutritive value and reported health benefits, it is a controversial fruit owing to its rich oxalate content. The present study aimed at investigating aroma and nutrient primary metabolites distribution in A. carambola fruits grown in Indonesia, Malaysia (its endemic origin) versus Egypt, and at different ripening stages. Two techniques were employed to assess volatile and non-volatile metabolites including headspace solid-phase micro-extraction (HS-SPME) joined with gas chromatography coupled with mass-spectrometry (GC-MS) and GC-MS post silylation, respectively. Twenty-four volatiles were detected, with esters amounting for the major class of volatiles in Egyptian fruit at ca. 66%, with methyl caproate as the major component, distinguishing it from other origins. In contrast, aldehydes predominated tropically grown fruits with the ether myristicin found exclusively in these. Primary metabolites profiling led to the identification of 117 metabolites viz. sugars, polyols and organic acids. Fructose (38–48%) and glucose (21–25%) predominated sugar compositions in ripe fruits, whereas sorbitol was the major sugar alcohol (2.4–10.5%) in ripe fruits as well. Oxalic acid, an anti-nutrient with potential health risks, was the major organic acid detected in all the studied fruits (1.7–2.7%), except the Malaysian one (0.07%). It increases upon fruit ripening, including considerable amounts of volatile oxalate esters detected via SPME, and which must not be omitted in total oxalate determinations for safety assessments.

Hypotensive effect of Eugenia dysenterica leaf extract is primarily related to its vascular action: The possible underlying mechanisms

ETHNOPHARMACOLOGICAL RELEVANCE

Eugenia dysenterica (ED) leaves are used in Brazil to treat cardiac diseases; however, there are no scientific data describing the effects of this species on cardiac activity.

AIM OF THE STUDY

To investigate the effect of ED aqueous leaf extract (EDLE) on hear rate (HR) and mean arterial pressure (MAP) of anaesthetised rats and its underlying mechanism of action.

MATERIAL AND METHODS

EDLE was analysed, and its proanthocyanidin composition was determined. After performing dose-effect curves for EDLE on HR and MAP, EDLE-induced hypotension was evaluated before and after atropine (AT), L-N(ω)-nitro-L-arginine methyl ester (L-NAME), hexamethonium (HXT), indomethacin (IND), carbenoxolone (CBX), or nifedipine (NFD) administration. The effect of proanthocyanidin-depleted extract (EDLE/P-) was also determined and compared to that of the EDLE with proanthocyanidins.

RESULTS

EDLE decreased the MAP in a dose-dependent manner; HR was decreased only with the highest and most toxic dose. Only CBX and NFD decreased EDLE-induced hypotension. Five polymeric series of proanthocyanidins were identified, which were mainly constituted by procyanidin and prodelphinidin units with B-type linkage and up to 12 flavan-3-ol units. EDLE/P- induced hypotension did not differ from that induced by EDLE.

CONCLUSIONS

The cardiovascular effects of EDLE were primarily related to its vascular action. EDLE-induced hypotensive effect appeared to involve L-type calcium channel blockage as well as myoendothelial gap junction signalling. The higher molecular weight proanthocyanidins from EDLE are unlikely to contribute to its cardiovascular effect.

Diet, Lifestyle and Cardiovascular Diseases: Linking Pathophysiology to Cardioprotective Effects of Natural Bioactive Compounds

Heart and blood vessels disorders comprise one of the main causes of death worldwide. Pharmacologically active natural compounds have been used as a complementary therapy in cardiovascular disease around the world in a traditional way. Dietary, natural bioactive compounds, as well as healthy lifestyles, are considered to prevent coronary artery diseases. Pre-clinical and clinical studies reported that consumption of plant-food bioactive derivatives including polyphenolic compounds, peptides, oligosaccharides, vitamins, unsaturated fatty acids possess protective effects on cardiovascular diseases. This review aims to summarize the cardiovascular risk factors, pre-clinical studies and clinical trials related to cardioprotective properties of the plant-food-derived bioactive compounds. Molecular mechanisms by the natural bioactive compounds exert their cardiovascular protective properties have also been highlighted.

Effect of an aqueous extract of Averrhoa carambola L. on endothelial function in rats with ventricular remodelling

Ventricular remodelling leads to cardiomyocyte hypertrophy, myocardial fibrosis, endothelial vasoactive substance changes and endothelial dysfunction. Our purpose was to research the effect of an aqueous extract of Averrhoa carambola L. (AEA) on endothelial function in rats with ventricular remodelling induced by isoprenaline. Rats were subjected to injection of isoprenaline and administration of various drugs. Vasoactive substances were measured, and the ventricular remodelling index was detected by the weighing method. Immunohistochemical analysis, pathological examination, Western blot and Masson's trichrome staining were performed. After AEA administration, the levels of transforming growth factor-β (TGF-β), angiotensin II (AngII), inducible NO synthase (iNOS), endothelin-converting enzyme (ECE), and endothelin 1 (ET-1); the ventricular remodelling index; and the collagen volume fraction were decreased, while the levels of total NO synthase (tNOS) and endothelial NO synthase (eNOS) were increased. The pathological examination results showed that apoptosis, fibrosis, necrosis and inflammatory infiltration of myocardial tissue were attenuated by AEA treatment. AEA might alleviate ventricular remodelling in rats by maintaining the balance of vasoactive substances and the function of the vascular endothelium.

Flavan-3-ols and 2-diglycosyloxybenzoates from the leaves of Averrhoa carambola

Averrhoa carambola L. (Oxalidaceae) was widely cultivated for fruits (star fruit), whereas the value of leaves remains to be discovered. Our study on the leaves yielded five flavan-3-ols (1-5) and two 2-diglycosyloxybenzoates. Their structures were determined by spectroscopic and chemical methods. Epicatechin-(5,6-bc)-4β-(p-hydroxyphenyl)-dihydro-2(3H)-pyranone (1) and benzyl 2-β-d-apiofuranosyl-(1 → 6)-β-d-glucopyranosyloxybenzoate (6) were new structures. 6-(S^-2-Pyrrolidinone-5-yl)epicatechin (4) and 6-(R-2-pyrrolidinone-5-yl)epicatechin (5) were obtained as monomeric diastereomer for the first time and their absolute configurations were determined by electronic circular dichroism (ECD) computation. Epicatechin-(7,8-bc)-4α-(p-hydroxyphenyl)-dihydro-2(3H)-pyranone (2), epicatechin-(7,8-bc)-4β-(p-hydroxyphenyl)-dihydro-2(3H)-pyranone (3), and methyl 2-β-d-apiofuranosyl-(1 → 6)-β-d-glucopyranosyloxybenzoate (7) were not previously reported from the genus Averrhoa. Compounds 1-5 showed more potent 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) radical cation and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activities and ferric reducing antioxidant power (FRAP) than l-ascorbic acid. Meanwhile 1 and 3 exhibited lipase and α-glucosidase inhibitory activities, respectively. The results clarified the structures of flavan-3-ols and 2-diglycosyloxybenzoates in the leaves and their antioxidant, lipase, and α-glucosidase inhibitory activities.

Evaluation of the possible hepatotoxic and nephrotoxic potentials of the Averrhoa carambola juice extract in female albino rats

Background Averrhoa carambola fruit is consumed by many people because of its sweetness and medicinal values. However, there is a dearth of researched information on its complete toxicity profile. This study investigated the possible toxicity potentials of star fruit juice in female albino rats. Methods Thirty-five rats assigned into seven groups of five rats each and administered with varying doses (0, 250, 500, 1000, 2000, 4000 and 5000 mg/kg) of the juice were used for acute toxicity studies. Another 20 rats assigned to four groups (A-D) of five rats each were administered the juice at 0, 600, 400 and 200 mg/kg body weight orally for 28 days. On the 29th day, whole blood, sera and vital organs were collected for hematological, serum biochemical and histopathological analyses, respectively. Results Acute study results indicate that the juice was safe even at 5000 mg/kg after 48 h. In the subacute studies, there were no significant (p < 0.05) differences in all hematological parameters, total protein, albumin and globulin values of the treated groups compared with those of the control group. The aspartate aminotransferase, alanine aminotransferase and alkaline phosphatase activities, as well as urea, creatinine and malondialdehyde values of the rats treated with the juice were significantly (p < 0.05) higher than those of the control rats in a dose-dependent manner. The liver and kidney histomorphologies of the rats treated with the juice showed lesions of degeneration and necrosis when compared with those of the control. Conclusion The juice of A. carambola is both nephrotoxic and hepatotoxic but had no deleterious effects on the hematology.

Antihypertensive activity of 80% methanol seed extract of Calpurnia aurea (Ait.) Benth. subsp. aurea (Fabaceae) is mediated through calcium antagonism induced vasodilation

ETHNOPHARMACOLOGICAL RELEVANCE

Calpurnia aurea (Ait.) Benth. subsp. aurea (CASA) (Fabaceae) seeds are used to treat hypertension in Ethiopian folklore medicine, particularly by Shinasha, Agew-awi and Amhara people in northwest Ethiopia. However, the claim has so far not been substantiated scientifically.

AIM OF THE STUDY

The study was conducted to evaluate the antihypertensive activity of 80% methanol extract of CASA in animal model of hypertension as well as its vasorelaxant effect and possible underlying mechanisms in isolated guinea pig aorta.

MATERIAL AND METHODS

Hypotensive and antihypertensive effect of CASA extract was determined in vivo through the intravenous (iv) route in normotensive and hypertensive anesthetized rats using 2-kidney-1-clip (2K1C) rat model. Ex vivo, guinea pig thoracic aortic rings were isolated and suspended in organ bath, and the vasodepressor effects as well as the mechanism of action of the extract were studied by means of isometric tension recording experiments.

RESULTS

The blood pressure fell dose-dependently and significantly in renal hypertensive and normotensive rats following i.v. administration, suggesting that the hydroalcoholic extract possesses hypotensive and antihypertensive effects. The extract also caused a dose-dependent relaxation of aorta pre-contracted with KCl at a concentration of 5-250mg/L, with a maximum relaxation of 92.1% achieved at 250mg/L. The relaxation mechanism was found to be independent of the muscarinic receptors, histamine receptors, ATP dependent K(+) channels, cyclooxygenase enzymes, cGMP/NO pathway and the endothelium system. The extract caused rightward shift of the Ca(++) dose-response curves, similar to that caused by verapamil, indicating that it produced vasorelaxation by inhibiting extracellular Ca(2+) influx.

CONCLUSIONS

The findings demonstrate that the plant is endowed with antihypertensive effect, providing evidence for its traditional use. The effect may be, at least in part, due to dilation of blood vessels through blockage of Ca(2+) channels.

Phytochemical and in vitro and in vivo biological investigation on the antihypertensive activity of mango leaves (Mangifera indica L.)

AIMS

The aim of this study was to investigate the antihypertensive effect of leaves Mangifera indica L. using in vitro and in vivo assays.

METHODOLOGY

The ethanol extract of leaves of M. indica was fractionated to dichloromethanic, n-butyl alcohol and aqueous fractions. The chemical composition of ethanolic extract and dichloromethanic fraction were evaluated by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). Antioxidant activity was evaluated in the DPPH scavenging activity assay. Angiotensin-converting enzyme (ACE) inhibitory activity was investigated using in vitro and in vivo assays. The chronic antihypertensive assay was performed in spontaneously hypertensive rats (SHRs) and Wistar rats treated with enalapril (10 mg/kg), dichloromethanic fraction (100 mg/kg; twice a day) or vehicle control for 30 days. The baroreflex sensitivity was evaluated through the use of sodium nitroprusside and phenylephrine. Cardiac hypertrophy was evaluated by morphometric analysis.

RESULTS

The dichloromethanic fraction exhibited the highest flavonoid, total phenolic content and high antioxidant activity. Dichloromethanic fraction elicited ACE inhibitory activity in vitro (99 ± 8%) similar to captopril. LC-MS/MS analysis revealed the presence of ferulic acid (48.3 ± 0.04 µg/g) caffeic acid (159.8 ± 0.02 µg/g), gallic acid (142.5 ± 0.03 µg/g), apigenin (11.0 ± 0.01 µg/g) and quercetin (203.3 ± 0.05 µg/g). The chronic antihypertensive effects elicited by dichloromethanic fraction were similar to those of enalapril, and the baroreflex sensitivity was normalized in SHR. Plasma ACE activity and cardiac hypertrophy were comparable with animals treated with enalapril.

CONCLUSIONS

Dichloromethanic fraction of M. indica presented an antihypertensive effect, most likely by ACE inhibition, with benefits in baroreflex sensitivity and cardiac hypertrophy. Altogether, the results of the present study suggest that the dichloromethanic fraction of M. indica leaves may have potential as a promoting antihypertensive agent.

Hypotensive effect and endothelium-dependent vascular action of leaves of Alpinia purpurata (Vieill) K. Schum

The aims of this study were to evaluate the chemical profile, vascular reactivity, and acute hypotensive effect (AHE) of the ethanolic extract of leaves of Alpinia purpurata (Vieill) K. Schum (EEAP). Its chemical profile was evaluated using HPLC-UV, ICP-OES, and colorimetric quantification of total flavonoids and polyphenols. The vascular reactivity of the extract was determined using the mesenteric bed isolated from WKY. AHE dose-response curves were obtained for both EEAP and inorganic material isolated from AP (IAP) in WKY and SHR animals. Cytotoxic and mutagenic safety levels were determined by the micronucleus test. Rutin-like flavonoids were quantified in the EEAP (1.8 ± 0.03%), and the total flavonoid and polyphenol ratios were 4.1 ± 1.8% and 5.1 ± 0.3%, respectively. We observed that the vasodilation action of EEAP was partially mediated by nitric oxide (·NO). The IAP showed the presence of calcium (137.76 ± 4.08 μg mg-1). The EEAP and IAP showed an AHE in WKY and SHR animals. EEAP did not have cytotoxic effects or cause chromosomic alterations. The AHE shown by EEAP could result from its endothelium-dependent vascular action. Rutin-like flavonoids, among other polyphenols, could contribute to these biological activities, and the calcium present in EEAP could act in a synergistic way.

In vivo hypotensive effect and in vitro inhibitory activity of some Cyperaceae species

In 1820, French naturalist August Saint Hillaire, during a visit in Espírito Santo (ES), a state in southeastern Brazil, reported a popular use of Cyperaceae species as antidote to snake bites. The plant may even have a hypotensive effect, though it was never properly researched. The in vitro inhibitory of the angiotensin converting enzyme (ACE) activity of eigth ethanolic extracts of Cyperaceae was evaluated by colorimetric assay. Total phenolic and flavonoids were determined using colorimetric assay. The hypotensive effect of the active specie (Rhychonospora exaltata, ERE) and the in vivo ACE assay was measured in vivo using male Wistar Kyoto (ERE, 0.01-100mg/kg), with acetylcholine (ACh) as positive control (5 µg/kg, i.v.). The evaluation of ACE in vivo inhibitory effect was performed comparing the mean arterial pressure before and after ERE (10 mg/kg) in animals which received injection of angiotensin I (ANG I; 0,03, 03 and 300 µg/kg, i.v.). Captopril (30 mg/kg) was used as positive control. Bulbostylis capillaris (86.89 ± 15.20%) and ERE (74.89 ± 11.95%, ERE) were considered active in the in vitro ACE inhibition assay, at 100 µg/mL concentration. ACh lead to a hypotensive effect before and after ERE's curve (-40±5% and -41±3%). ERE showed a dose-dependent hypotensive effect and a in vivo ACE inhibitory effect. Cyperaceae species showed an inhibitory activity of ACE, in vitro, as well as high content of total phenolic and flavonoids. ERE exhibited an inhibitory effect on both in vitro and in vivo ACE. The selection of species used in popular medicine as antidotes, along with the in vitro assay of ACE inhibition, might be a biomonitoring method for the screening of new medicinal plants with hypotensive properties.

The effects of hydroxysafflor yellow A on blood pressure and cardiac function

AIM OF THE STUDY

This work aims to investigate the effects of HSYA on cardiac function and blood pressure.

MATERIALS AND METHODS

To evaluate changes in mean arterial pressure (MAP) and heart rate (HR), different groups of pentobarbitone-anesthetized normotensive and spontaneously hypertensive rats (SHR) were treated with intravenous HSYA (0.1-3 mg/kg). Isolated WKY rat hearts in Langendorff system were employed for examining the effect of HSYA on hemodynamic. After 30 min equilibration time the isolated hearts were perfused with HSYA (30 μmol/L) in a stepwise fashion. Potassium channel inhibitors were used to determine the role of potassium channel activation in HSYA effect.

RESULTS

Intravenous injection of the HSYA significantly reduced MAP and HR in both normotensive rats and SHR in a dose-dependent manner. HSYA reduced left ventricular systolic pressure (LVSP), left ventricular end-diastolic pressure (LVEDP), the maximum rate of increase of left ventricular pressure (+dp/dt(max)) and heart rate (HR) in a dose-dependent manner. HSYA had no remarkable effect on the maximum rate of decrease of left ventricular pressure (-dp/dt(max)); BK(Ca) and K(ATP) blocker can weakened the inhibitory effect of HSYA on heart function and HR, but K(V) and K(ACh) blocker did not significantly weaken the HSYA effects.

CONCLUSION

Our results show that HSYA could significantly reduce blood pressure and heart rate, which may be related to activation of BK(Ca) and K(ATP) channels.