Antihypertensive effect of roselle (Hibiscus sabdariffa) calyx infusion in spontaneously hypertensive rats and a comparison of its toxicity with that in Wistar rats

Evaluation of the antioxidant potential of Salvia miltiorrhiza ethanol extract in a rat model of ischemia-reperfusion injury

The present study was undertaken to evaluate the protection potential of ethanol extract of Salvia miltiorrhiza (SMEE) against oxidative injury in the ischemia-reperfusion (I/R) model of rats in vivo. Rats were divided into six groups of 10 rats each. Group I/R model and sham were fed with a standard rat chow, groups SMEE I and SMEE II were fed with a standard rat chow and 400 or 800 mg/kg b.w. ethanol extract for 12 days before the beginning of I/R studies. Positive control group was fed with a standard rat chow and salvianolic acid B (55 mg/kg b.w.) or tanshinone II-A (55 mg/kg b.w.) for 12 days before the beginning of I/R studies. To produce I/R, the left anterior descending artery (LAD) was occluded in anesthetized rats for 15 min, followed by 120 min reperfusion. Infarct sizes were found significantly decreased in SMEE-treated and positive control groups compared to I/R model group. Serum AST, LDH and CK-MB activities were significantly reduced and myocardium Na⁺-K⁺ ATPase, Ca²⁺-Mg²⁺ ATPase activities and antioxidant enzyme activities (SOD, CAT, GSH-Px) were markedly increased in SMEE-treated and salvianolic acid B or tanshinone II-A positive control groups compared to the I/R model group. Pretreatment of S. miltiorrhiza ethanol extract and salvianolic acid B or tanshinone II-A dose-dependently reduced significantly myocardium MDA level, ROS and NOS activities and enhanced myocardium GSH level in I/R rats compared to I/R rats model. In conclusion, we clearly demonstrated that S. miltiorrhiza ethanol extract pretreatment can decrease oxidative injury in rats subjected to myocardial I/R.

The effect of hibiscus sabdariffa on lipid profile, creatinine, and serum electrolytes: a randomized clinical trial

Background. Hibiscus Sabdariffa L. (HS), a member of malvaceae family, is a medicinal plant with a worldwide fame. Its effect on reducing serum lipids is mentioned in several studies. The purpose of this study was to assess the efficacy of this plant in reducing the serum's lipids in hypertensive patients. Materials and Methods. Ninety hypertensive patients were randomly assigned to receive Hibiscus Sabdariffa (HS) tea or black tea for 15 days. The patients were asked to drink the tea within 20 minutes following its preparation. This process had to be repeated two times, daily. Patient's FBS and lipid profile were collected at the first visit day (day 0) and on the day 30. Results. There was no significant differences between pre and post experiment values within the two groups. An upward trend in total cholesterol, HDL, and LDL cholesterol was evident in both groups. The increase in total and HDL cholesterol in both groups relative to their initial values were significant. Conclusion. Hibiscus Sabdariffa is probably a safe medicinal plant. No significant harmful changes in cholesterol, triglyceride, BUN, serum creatinine, Na and K levels were observed within 15 days after the discontinuation of the medication.

Effects of Hibiscus sabdariffa extract powder and preventive treatment (diet) on the lipid profiles of patients with metabolic syndrome (MeSy)

Insulin resistance, obesity, hypertension, and dyslipidemia are strongly associated with metabolic syndrome (MeSy), which is considered to be a reversible clinical stage before its evolution to coronary heart disease and diabetes. Currently, the antihypertensive and hypolipidemic properties of aqueous Hibiscus sabdariffa extracts (HSE) have been demonstrated in clinical trials and in vivo experiments. The aim of the present study was to evaluate the effects of a Hibiscus sabdariffa extract powder (HSEP) and a recognized preventive treatment (diet) on the lipid profiles of individuals with and without MeSy according to the National Cholesterol Education Program Adult Treatment Panel III (NCEP-ATP III) criteria. The protocol was a follow-up study carried out in a factorial, randomized design (T1=preventive treatment comprises Diet, T2=HSEP, T3=HSEP+preventive treatment (Diet) X MeSy, non-MeSy individuals). A total daily dose of 100 mg HSEP was orally administered in capsules for one month. The preventive treatment (diet) was selected according to NCEP-ATP III recommendations and adjusted individually. Total cholesterol, LDL-c, HDL-c, VLDL-c, triglycerides, glucose, urea, creatinine, AST, and ALT levels in the blood were determined in all individuals pre- and post-treatment. The MeSy patients treated with HSEP had significantly reduced glucose and total cholesterol levels, increased HDL-c levels, and an improved TAG/HDL-c ratio, a marker of insulin resistance (t-test p<0.05). Additionally, a triglyceride-lowering effect was observed in MeSy patients treated with HSEP plus diet, and in individuals without MeSy treated with HSEP. Significant differences in total cholesterol, HDL-c, and the TAG/HDL-c ratio were found when the means of absolute differences among treatments were compared (ANOVA p<0.02). Therefore, in addition to the well documented hypotensive effects of Hibiscus sabdariffa, we suggest the use of HSEP in individuals with dyslipidemia associated with MeSy.

The aqueous extract of Hibiscus sabdariffa calices modulates the production of monocyte chemoattractant protein-1 in humans

Diet supplementation and/or modulation is an important strategy to significantly improve human health. The search of plants as additional sources of bioactive phenolic compounds is relevant in this context. The aqueous extract of Hibiscus sabdariffa is rich in anthocyanins and other phenolic compounds including hydroxycitric and chlorogenic acids. Using this extract we have shown an effective protection of cultured peripheral blood mononuclear cells from the cellular death induced by H(2)O(2) and a significant role in the production of inflammatory cytokines. In vitro, the extract promotes the production of IL-6 and IL-8 and decreases the concentration of MCP-1 in supernatants in a dose-dependent manner. In humans, the ingestion of an acute dose of the extract (10g) was well tolerated and decreased plasma MCP-1 concentrations significantly without further effects on other cytokines. This effect was not due to a concomitant increase in the antioxidant capacity of plasma. Instead, its mechanisms probably involve a direct inhibition of inflammatory and/or metabolic pathways responsible for MCP-1 production, and may be relevant in inflammatory and chronic conditions in which the role of MCP-1 is well established. If beneficial effects are confirmed in patients, Hibiscus sabdariffa could be considered a valuable traditional herbal medicine for the treatment of chronic inflammatory diseases with the advantage of being devoid of caloric value or potential alcohol toxicity.

Hibiscus sabdariffa L. tea (tisane) lowers blood pressure in prehypertensive and mildly hypertensive adults

In vitro studies show Hibiscus sabdariffa L., an ingredient found in many herbal tea blends and other beverages, has antioxidant properties, and, in animal models, extracts of its calyces have demonstrated hypocholesterolemic and antihypertensive properties. Our objective in this study was to examine the antihypertensive effects of H. sabdariffa tisane (hibiscus tea) consumption in humans. A randomized, double-blind, placebo-controlled clinical trial was conducted in 65 pre- and mildly hypertensive adults, age 30-70 y, not taking blood pressure (BP)-lowering medications, with either 3 240-mL servings/d of brewed hibiscus tea or placebo beverage for 6 wk. A standardized method was used to measure BP at baseline and weekly intervals. At 6 wk, hibiscus tea lowered systolic BP (SBP) compared with placebo (-7.2 +/- 11.4 vs. -1.3 +/- 10.0 mm Hg; P = 0.030). Diastolic BP was also lower, although this change did not differ from placebo (-3.1 +/- 7.0 vs. -0.5 +/- 7.5 mm Hg; P = 0.160). The change in mean arterial pressure was of borderline significance compared with placebo (-4.5 +/- 7.7 vs. -0.8 +/- 7.4 mm Hg; P = 0.054). Participants with higher SBP at baseline showed a greater response to hibiscus treatment (r = -0.421 for SBP change; P = 0.010). No effects were observed with regard to age, gender, or dietary supplement use. These results suggest daily consumption of hibiscus tea, in an amount readily incorporated into the diet, lowers BP in pre- and mildly hypertensive adults and may prove an effective component of the dietary changes recommended for people with these conditions.

The effectiveness of Hibiscus sabdariffa in the treatment of hypertension: a systematic review

INTRODUCTION

Hypertension is a common global health problem with significant mortality and morbidity. Hibiscus sabdariffa is a plant known in many countries and is consumed as hot and cold drinks In addition to its use in folk medicine; it has been suggested as treatment for many conditions including hypertension.

OBJECTIVES

The objectives of this review were to examine the evidence of effectiveness and safety of hibiscus in the treatment of hypertension.

METHODS

We searched several medical databases (MEDLINE, EMBASE, CINAHL, Cochrane Central Register of Controlled Trials, and the specialized register of the Cochrane Hypertension Group and the general engine Google) to January 2009. We included randomized controlled trials that had examined Hibiscus's effectiveness and safety in the treatment of primary hypertension in adults. Two authors independently selected the trials for the review, extracted the data, and critically appraised the included studies.

RESULTS

Four trials, with a total of 390 patients, met our inclusion criteria. Two studies compared Hibiscus sabdariffa to black tea; one study compared it to captopril and one to lisinopril. The studies found that Hibiscus had greater blood pressure reduction than tea but less than the ACE-inhibitors. However, all studies, except one, were short term and of poor quality with a Jadad scoring of <3 and did not meet international standards.

CONCLUSION

The four randomized controlled studies identified in this review do not provide reliable evidence to support recommending Hibiscus sabdariffa for the treatment of primary hypertension in adults.

Aqueous extract of Hibiscus sabdariffa L. decelerates acetaminophen-induced acute liver damage by reducing cell death and oxidative stress in mouse experimental models

BACKGROUND

Acetaminophen (AAP)-induced oxidative stress can cause cell death to induce liver damage. The antioxidant effect of Hibiscus sabdariffa L. (HS) was shown in previous studies. In this study the effect of HS extract (HSE) on AAP-induced liver injury in BALB/c mice was investigated.

RESULTS

In vivo, BALB/c mice were fed orally with 200, 400 or 600 mg kg(-1) HSE for 2 weeks and then injected with 1000 mg kg(-1) AAP. Pretreatment with HSE decreased lipid peroxidation and increased catalase activity and glutathione level. It also decreased AAP-induced liver injury, accompanied by decreased expression of pJNK, Bax and tBid in the liver. Additionally, HSE protected BALB/c normal liver cells from AAP-induced damage in vitro.

CONCLUSION

It has been demonstrated that HSE can protect the mouse liver from AAP-induced injury and that the protective mechanism might involve decreasing oxidative stress and reducing cell death.

Roselle for hypertension in adults

BACKGROUND

Hypertension is considered a serious health problem worldwide. Controlling and lowering blood pressure have a significant benefit to the hypertensive patients because hypertension is a risk factor for stroke, heart disease and cardiovascular disease. A tropical plant called Roselle, or Red Sorrel in English-speaking countries, has been used both as a thirst-quenching drink and for medical purposes.

OBJECTIVES

To explore the effect of Roselle on blood pressure in hypertensive adult patients.

SEARCH STRATEGY

The following databases were searched (Date of most recent search was September 2009): - Cochrane Database of Systematic Reviews (2nd Quarter 2009) - DARE (2nd Quarter 2009) - Ovid MEDLINE (1950 to Present with Daily Update) - EMBASE (1980 to 2009 Week 22) - AMED (1985 to May 2009) - EBSCO CINAHL - BIOSIS (1969 to 2008) - AGRICOLA (1970 to May 2009) - Food Science and Technology Abstract (1969 to 2009 June Week 1) - International Pharmaceutical Abstracts - International Bibliographic Information on Dietary Supplements - Clinical Trials.gov and Current Controlled Trials - OpenSIGLE - Hand searching of journals - ISI Web of Knowledge

SELECTION CRITERIA

We sought randomised control trials (RCTs) evaluating use of any forms of Roselle with placebo or no treatment in hypertensive patients. Change in trough and/or peak systolic and diastolic blood pressure were primary outcomes. Secondary outcomes were withdrawals due to adverse effects, change of pulse pressure and change of heart rate.

DATA COLLECTION AND ANALYSIS

Two review authors (C Ngamjarus, CN and P Pattanittum, PP) independently scanned titles and abstracts, as well as independently screened the full reports of the potentially relevant studies. At each stage, the results were compared and disagreements were solved by discussion.

MAIN RESULTS

No studies were identified that met the inclusion criteria. However, one abstract of an ongoing study is likely to meet the inclusion criteria, when completed.

AUTHORS' CONCLUSIONS

There is insufficient evidence to support the benefit of Roselle for either controlling or lowering blood pressure in patients with hypertension. Based on the information of this review, there is a clear need to develop well-designed studies to assess the efficacy of Roselle on hypertensive patients.

In vitro vasorelaxation mechanisms of bioactive compounds extracted from Hibiscus sabdariffa on rat thoracic aorta

BACKGROUND

In this study, we suggested characterizing the vasodilator effects and the phytochemical characteristics of a plant with food usage also used in traditional treatment of arterial high blood pressure in Senegal.

METHODS

Vascular effects of crude extract of dried and powdered calyces of Hibiscus sabdariffa were evaluated on isolated thoracic aorta of male Wistar rats on organ chambers. The crude extract was also enriched by liquid-liquid extraction. The various cyclohexane, dichloromethane, ethyl acetate, butanol extracts obtained as well as the residual marc were subjected to Sephadex LH-20 column chromatography. The different methanolic eluate fractions were then analyzed by Thin Layer (TLC) and High Performance Liquid Chromatography (HPLC) and their vascular effects also evaluated.

RESULTS

The H. Sabdariffa crude extract induced mainly endothelium-dependent relaxant effects. The endothelium-dependent relaxations result from NOS activation and those who not dependent to endothelium from activation of smooth muscle potassium channels. The phytochemical analysis revealed the presence of phenolic acids in the ethyl acetate extract and anthocyans in the butanolic extract. The biological efficiency of the various studied extracts, in term of vasorelaxant capacity, showed that: Butanol extract > Crude extract > Residual marc > Ethyl acetate extract. These results suggest that the strong activity of the butanolic extract is essentially due to the presence of anthocyans found in its fractions 43-67.

CONCLUSION

These results demonstrate the vasodilator potential of hibiscus sabdariffa and contribute to his valuation as therapeutic alternative.

Effect of Hibiscus sabdariffa L. dried calyx ethanol extract on fat absorption-excretion, and body weight implication in rats

The effect of Hibiscus sabdariffa L. (Hs) calyx extract on fat absorption-excretion and body weight in rats, was investigated. Rats were fed with either a basal diet (SDC = Control diet) or the same diet supplemented with Hs extracts at 5%, 10% and 15% (SD₅, SD₁₀ and SD₁₅). Only SD₅ did not show significant increases in weight, food consumption and efficiency compared to SD_C. The opposite occurred in SD₁₅ group which showed a significant decrease for these three parameters. The SD₁₀ responses were similar to SD₁₅, with the exception of food consumption. In both SD_C and SD₅ groups, no body weight loss was observed; however, only in the latter group was there a significantly greater amount of fatty acids found in feces. A collateral effect emerging from the study is that components of Hs extract at the intermediate and greater concentrations used in this experiment could be considered possible antiobesity agents.

In vitro anti-Helicobacter pylori activity of diallyl sulphides and protocatechuic acid

The in vitro inhibitory effects of diallyl disulphide (DADS), diallyl trisulphide (DAT), roselle calyx extract and protocatechuic acid (PA) on the growth of Helicobacter pylori (15 susceptible, 11 clarithromycin-resistant and 9 metronidazole-resistant strains) were studied. The inhibition zone was determined after each agent had been heated at 25, 60, 100 degrees C for 60 min. The minimal inhibitory concentration (MIC) of each agent was determined by the tube dilution assay. The results showed that heat treatment did not affect the anti-H. pylori activity of DADS, DAT, roselle calyx extract and PA, and the MIC values of these agents against test H. pylori strains were in the range 8-64 mg/L. The time-kill study assay for DAT and PA at 1x MIC was monitored in Muller Hinton broth supplemented with 10% horse blood or mice stomach homogenate. Both DAT and PA inhibited the growth of all test H. pylori in broth and mice stomach homogenate (p < 0.05); however, the inhibitory effects of these two agents were less in mice stomach homogenate than in broth (p < 0.05). DAT at 4, 6, 8, 10, 12, 14 mg/L and PA at 8, 16, 24, 32, 40, 48 mg/L were used for urease activity assay. These two agents significantly reduced urease activity of test H. pylori strains (p < 0.05), in which DAT and PA at 1x MIC reduced the urease activity of H. pylori to 70% and 40%, respectively. These agents, based on their lower MIC values and heat tolerance, might be useful in the prevention or therapy of H. pylori.

Herbal medicines as diuretics: a review of the scientific evidence

There is increasing interest in the health and wellness benefits of herbs and botanicals. This is with good reason as they might offer a natural safeguard against the development of certain conditions and be a putative treatment for some diseases. One such area may be the lowering of blood pressure in those where it is elevated (i.e., hypertension). One class of clinical medicines used to lower blood pressure are known as diuretics and work by increasing the excretion of urine from the body as well as the amount of sodium in urine. There are a growing number of studies purporting diuretic effects with traditional medicines. The aim of this article was to review these studies and identify which extracts promote diuresis (which we assessed on terms of urine excreted and urinary sodium excretion) and also to identify the research needs in this area. We identified a number of species and genuses reporting diuretic effects. Of these, the most promising, at the present time, are the species Foeniculum vulgare, Fraxinus excelsior, Hibiscus sabdariffa, Petroselinum sativum and Spergularia purpurea, and species from the genuses Cucumis (Cucumis melo and Cucumis trigonus), Equisetum (Equisetum bogotense, Equisetum fluviatile, Equisetum giganteum, Equisetum hiemale var. affine and Equisetum myriochaetum), Lepidium (Lepidium latifolium and Lepidium sativum), Phyllanthus (Phyllanthus amarus, Phyllanthus corcovadensis and Phyllanthus sellowianus) and Sambucus (Sambucus mexicana and Sambucus nigra). However, there the number of studies is limited and we recommend that further studies be conducted to confirm reported effects. Such evidence is needed to provide scientific credence to the folklore use of traditional medicines and even be helpful in the development of future medicines, treatments and treatment guidelines.

Antihypertensive effect of an aqueous extract of the calyx of Hibiscus sabdariffa

The present study was designed to investigate the efficacy of an aqueous calyx extract of Hibiscus sabdariffa (HS) in two forms of experimental hypertension: salt-induced and L-NAME (N(omega)-L-arginine methyl ester)-induced and in normotensive controls. The blood pressure and heart rate fell dose-dependently in both the hypertensive and normotensive rats after intravenous injection of 1-125 mg/kg of HS, suggesting that HS possesses anti-hypertensive, hypotensive and negative chronotropic effects. The fall in mean arterial pressure was significantly pronounced in the hypertensive rats (salt-induced: 94.4+/-8.6 mm Hg; L-NAME-induced: 136.5+/-10.3 mm Hg) than in the normotensive controls (50.2+/-5.1 mm Hg; P<0.05).

Mechanisms of the anti-hypertensive effect of Hibiscus sabdariffa L. calyces

Previous studies have demonstrated the anti-hypertensive effects of Hibiscus sabdariffa L. (HS) in both humans and experimental animals. To explore the mechanisms of the anti-hypertensive effect of the HS, we examined the effects of a crude methanolic extract of the calyces of HS (HSE) on vascular reactivity in isolated aortas from spontaneously hypertensive rats. HSE relaxed, concentration-dependently, KCl (high K(+), 80 mM)- and phenylephrine (PE, 1 microM)-pre-contracted aortic rings, with a greater potency against the alpha(1)-adrenergic receptor agonist. The relaxant effect of HSE was partly dependent on the presence of a functional endothelium as the action was significantly reduced in endothelium-denuded aortic rings. Pretreatment with atropine (1 microM), L-NAME (10 microM) or methylene blue (10 microM), but not indomethacin (10 microM), significantly blocked the relaxant effects of HSE. Endothelium-dependent and -independent relaxations induced by acetylcholine and sodium nitroprusside, respectively, were significantly enhanced in aortic rings pretreated with HSE when compared to those observed in control aortic rings. The present results demonstrated that HSE has a vasodilator effect in the isolated aortic rings of hypertensive rats. These effects are probably mediated through the endothelium-derived nitric oxide-cGMP-relaxant pathway and inhibition of calcium (Ca(2+))-influx into vascular smooth muscle cells. The present data further supports previous in vivo findings and the traditional use of HS as an anti-hypertensive agent.

Chemopreventive properties of Hibiscus sabdariffa L. on human gastric carcinoma cells through apoptosis induction and JNK/p38 MAPK signaling activation

Gastric cancer is a common malignancy in many countries of the world, especially in Asia. Prevention is likely to be the most effective means of not only reducing the incidence but also mortality from this disease. The term 'chemoprevention' has been referred to the prevention of cancer using specific agents to suppress or reverse the carcinogenic process. In recent years, attention has been focused on the anticancer properties of edible plants, an important role in the prevention of disease. Hibiscus sabdariffa Linne (Malvaceae), an attractive plant believed to be native to Africa, is cultivated in the Sudan and Eastern Taiwan. The purpose of this study was to examine whether the plant, H. sabdariffa extracts (HSE), affects the apoptosis of AGS cells. Using a set of apoptotic detection assays, they showed that HSE induced cytotoxicity and apoptosis of AGS cells in a concentration-dependent manner but is ineffective in Chang liver cells. The result also revealed increased phosphorylation in p38, JNK and c-Jun, cytochrome c release, and expression of Fas, FasL, Bax, and t-Bid in the HSE-treated AGS cells. We further used MAPK inhibitors to evaluate their effect on the HSE-induced AGS death. The data showed that SB203580 (p38 inhibitor), JNK inhibitor I and II or transfection with the mutant JNK expression vector had strong potential in inhibiting AGS cells apoptosis and related proteins expression. Finally, we suggested that HSE mediated AGS apoptosis via the JNK/p38 signaling cascade. According to these results, HSE could be developed as a chemopreventive agent.

Hibiscus anthocyanins-rich extract inhibited LDL oxidation and oxLDL-mediated macrophages apoptosis

The oxidative modification of low-density lipoprotein (LDL) plays a key role in the pathogenesis of atherosclerosis. Anti-oxidative reagents, which can effectively inhibit LDL oxidation, may prevent atherosclerosis via reducing early atherogenesis, and slowing down the progression to advance stages. As shown in previous studies Hibiscus sabdariffa L. is a natural plant containing a lot of pigments that was found to possess anti-oxidative of activity. Therefore, in this study, we evaluated the anti-oxidative activity of Hibiscus anthocyanins (HAs) by measuring their effects on LDL oxidation (in cell-free system) and anti-apoptotic abilities (in RAW264.7 cells). HAs have been tested in vitro examining their relative electrophoretic mobility (REM), Apo B fragmentation, thiobarbituric acid relative substances (TBARS) and radical 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging activity assay. The anti-oxidative activity of HAs was defined by relative electrophoretic mobility of oxLDL (decrease of 50% at 2 mg/ml), fragmentation of Apo B (inhibition of 61% at 1mg/ml), and TBARS assay (IC(50): 0.46 mg/ml) in the Cu(2+)-mediated oxidize LDL. Furthermore, the addition of >0.1 mg/ml of HAs could scavenge over 95% of free DPPH radicals, HAs showed strong potential in inhibiting LDL oxidation induced by copper. In addition, to determine whether oxLDL-induced apoptosis in macrophages is inhibited by HAs, we studied the viability, morphology and caspase-3 expression of RAW 264.7 cells. MTT assay, Leukostate staining analysis and Western blotting reveals that HAs could inhibit oxLDL-induced apoptosis. According to these findings, we suggest that HAs may be used to inhibit LDL oxidation and oxLDL-mediated macrophage apoptosis, serving as a chemopreventive agent. However, further investigations into the specificity and mechanism(s) of HAs are needed.

The protective effects of Hibiscus sabdariffa extract on CCl4-induced liver fibrosis in rats

Dried flower Hibiscus sabdariffa L. (HSE) extracts, a local soft drink material and medicinal herb, were studied for their protective effects against liver fibrosis induced using carbon tetrachloride (CCl(4)) in rats. Male Wistar rats were administered CCl(4) by intraperitoneal injection for 7weeks and received a normal diet or normal diet with various HSE doses (1-5%) for 9weeks. HSE significantly reduced the liver damage including steatosis and fibrosis in a dose dependent manner. Moreover, HSE significantly decreased the elevation in plasma aspartate aminotransferase (AST) and alanine aminotransferase (ALT). It also restored the decrease in glutathione content and inhibited the formation of lipid peroxidative products during CCl(4) treatment. In the primary culture, HSE also significantly inhibited the activation of the hepatic stellate cells. These results suggested that HSE may protect the liver against CCl(4)-induced fibrosis. This protective effect appears due to HSEs antioxidant properties.

Phytochemical, pharmacological and toxicological aspects ofHibiscus sabdariffa L.: a review

This article reviews the reported phytochemical, pharmacological and toxicological properties of Hibiscus sabdariffa L. (English: roselle, red sorrel; Arabic: karkade), the calyces of which are used in many parts of the world to make cold and hot drinks. Nutritionally, these contain ascorbic acid (vitamin C). In folk medicine, the calyx extracts are used for the treatment of several complaints, including high blood pressure, liver diseases and fever. The pharmacological actions of the calyx extracts include strong in vitro and in vivo antioxidant activity. In rats and rabbits, the extract showed antihypercholesterolaemic, antinociceptive and antipyretic, but not antiinflammatory activities. In rat and man a strong antihypertensive action has been demonstrated. The effects of the calyx extracts on smooth muscles in vitro are variable, but they mostly inhibit the tone of the isolated muscles. In healthy men, consumption of H. sabdariffa has resulted in significant decreases in the urinary concentrations of creatinine, uric acid, citrate, tartrate, calcium, sodium, potassium and phosphate, but not oxalate. Oil extracted from the plant's seeds has been shown to have an inhibitory effect on some bacteria and fungi in vitro. The plant extracts are characterized by a very low degree of toxicity. The LD50 of H. sabdariffa calyx extract in rats was found to be above 5000 mg/kg. A single report has suggested that excessive doses for relatively long periods could have a deleterious effect on the testes of rats. In view of its reported nutritional and pharmacological properties and relative safety, H. sabdariffa and compounds isolated from it (for example, anthocyanins and Hibiscus protocatechuic acid) could be a source of therapeutically useful products.

Hibiscus polyphenol-rich extract induces apoptosis in human gastric carcinoma cells via p53 phosphorylation and p38 MAPK/FasL cascade pathway

In view of the continuing need for effective anticancer agents, and the association of diet with reduced cancer risk, edible plants are increasingly being considered as sources of anticancer drugs. Hibiscus sabdariffa Linne (Malvaceae), an attractive plant believed to be native to Africa, is cultivated in the Sudan and Eastern Taiwan. Polyphenols had been demonstrated previously to possess antioxidative and antitumor promoting effects. In this study, investigations were conducted to examine the mechanism of the anticancer activity of H. sabdariffa L., Hibiscus polyphenol-rich extracts (HPE). Using HPLC assay, HPE was demonstrated to contain various polyphenols. HPE induced cell death of eight kinds of cell lines in a concentration-dependent manner. Among them human gastric carcinoma (AGS) cells were the most susceptible to HPE (0.95 mg/mL HPE inhibited its growth by 50%). Our results revealed that AGS cells underwent DNA fragmentation, and had an increase in the distribution of hypodiploid phase (apoptotic peak, 52.36%) after a 24-h treatment with HPE (2.0 mg/mL). This effect of HPE in AGS cells might be mediated via p53 signaling and p38 MAPK/FasL cascade pathway, as demonstrated by an increase in the phosphorylation of p53 and the usage of a specific p38 inhibitor, SB203580. Thus, our data present the first evidence of HPE as an apoptosis inducer in AGS cells and these findings may open interesting perspectives to the strategy in human gastric cancer treatment.

In vitro antibacterial activity of roselle calyx and protocatechuic acid

The in vitro inhibitory effect of roselle calyx and protocatechuic acid, a compound derived from roselle calyx, on the growth of methicillin-resistant Staphylococcus aureus, Klebsiella pneumoniae, Pseudomonas aeruginosa and Acinetobacter baumannii was studied. The data from inhibition zone and minimum inhibitory concentration (MIC) values showed that both roselle calyx extract and protocatechuic acid inhibited effectively the growth of all test bacterial pathogens, the antibacterial activity of protocatechuic acid being significantly greater than roselle calyx (p < 0.05). Furthermore, heat treatment did not affect the antibacterial activity of roselle calyx and protocatechuic acid against all test pathogens. The time-kill data from protocatechuic acid showed this agent provided concentration dependent antibacterial activities in broth and human plasma (p < 0.05); however, protocatechuic acid showed less inhibitory activity in human plasma than in broth (p < 0.05). These agents based on their lower MIC values, heat tolerance and concentration dependent antibacterial activity may be useful in clinical infection prevention or therapy.

Effectiveness and tolerability of a standardized extract from Hibiscus sabdariffa in patients with mild to moderate hypertension: a controlled and randomized clinical trial

In order to compare the antihypertensive effectiveness and tolerability of a standardized extract from Hibiscus sabdariffa with captopril, a controlled and randomized clinical trial was done. Patients from 30 to 80 years old with diagnosed hypertension and without antihypertensive treatment for at least 1 month before were included. The experimental procedure consisted of the administration of an infusion prepared with 10 g of dry calyx from H. sabdariffa on 0.51 water (9.6 mg anthocyanins content), daily before breakfast, or captopril 25 mg twice a day, for 4 weeks. The outcome variables were tolerability, therapeutic effectiveness (diastolic reduction > or = 10 mm Hg) and, in the experimental group, urinary electrolytes modification. Ninety subjects were included, 15 withdrew from the study due to non-medical reasons; so, the analysis included 39 and 36 patients from the experimental and control group, respectively. The results showed that H. sabdariffa was able to decrease the systolic blood pressure (BP) from 139.05 to 123.73mm Hg (ANOVA p < 0.03) and the diastolic BP from 90.81 to 79.52mm Hg (ANOVA p < 0.06). At the end of the study, there were no significant differences between the BP detected in both treatment groups (ANOVA p > 0.25). The rates of therapeutic effectiveness were 0.7895 and 0.8438 with H. sabdariffa and captopril, respectively (chi2, p > 0.560), whilst the tolerability was 100% for both treatments. A natriuretic effect was observed with the experimental treatment. The obtained data confirm that the H. sabdariffa extract, standardized on 9.6mg of total anthocyanins, and captopril 50 mg/day, did not show significant differences relative to hypotensive effect, antihypertensive effectiveness, and tolerability.

Hibiscus sabdariffa extract inhibits the development of atherosclerosis in cholesterol-fed rabbits

Hibiscus sabdariffa L., a local soft drink material and medicinal herb, is usually used effectively in native medicines against hypertension, pyrexia, and liver disorders. Here, we report an extract, HSE (H. sabdariffa extract), which is designed to exhibit hypolipidemia and antiatherosclerotic effects in rabbits with experimental atherosclerosis. New Zealand White rabbits were fed with a normal diet, high cholesterol (1.3%), lard oil (3%) diet (HCD) with or without 0.5 or 1% HSE for 10 weeks. The levels of triglyceride, cholesterol, and low-density lipoprotein cholesterol (LDL-C) were lower in the serum of rabbits fed HCD plus HSE than in the serum of rabbits fed HCD. Feeding HSE (0.5 and 1% in the diet) to rabbits significantly reduced severe atherosclerosis in the aorta. Histopathological examination showed that HSE reduced foam cell formation and inhibited smooth muscle cell migration and calcification in the blood vessel of rabbits. These results suggest that HSE inhibits serum lipids and shows an antiatherosclerotic activity.

Chronic administration of aqueous extract of Hibiscus sabdariffa attenuates hypertension and reverses cardiac hypertrophy in 2K-1C hypertensive rats

The effect of aqueous extract of petals of Hibiscus sabdariffa (HS) on the established stages of 2-Kidney, 1-Clip renovascular hypertension was investigated in Sprague-Dawley rats. Renovascular hypertension was induced by subjecting the animals to left renal artery clamping using a 0.2mm silver clip under ether anesthesia. Sham-operated (Sh-Op) rats served as controls. Six weeks after renal artery clamping, one group of hypertensive rats (blood pressure (BP) >140 mmHg) received HS (250 mg/kg/day) in drinking water (2K-1C+HS). The second group (2K-1C) and the sham-operated (Sh-Op) controls, received drinking water. BP was monitored weekly using rat-tail plethysmography. After 8 weeks, 2K-1C+HS had a reduction in systolic BP (139.6+/-1.6 mmHg) compared to 2K-1C (174+/-2.4 mmHg, n=5; P<0.001). No significant difference was found in BP of 2K-1C+HS and Sh-Op (139.6+/-1.6 mmHg versus 132+/-3.4 mmHg). A reduction in heart rate in 2K-1C+HS was observed (388+/-3.7 bpm versus 444+/-6.8 bpm in 2K-1C and 416+/-9.3 in Sh-Op, n=5; P<0.001). The hearts of 2K-1C were heavier than those of 2K-1C+HS (0.74+/-0.03 g versus 0.66+/-0.03 g, n=5; P<0.05). Cardiac weight of 2K-1C+HS was comparable to those of Sh-Op (0.57+/-0.04 g). Serum creatinine and plasma electrolytes were not different from controls. This study suggests that HS exhibits antihypertensive and cardioprotective effects in vivo and supports the public belief that HS may be a useful antihypertensive agent.