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

Chemical profile of Roselle extract and its inhibitory activities on three digestive enzymes in vitro and in vivo

Roselle is rich in an extensive diversity of beneficial substances, including phenolic acids, amino acids, anthocyanins, vitamins, and flavonoids. Herein, the chemical constituents in Roselle extract (RE) were identified by UPLC-DAD-QTOF-MS. Besides, its inhibitory effects on three digestive enzymes, i.e. α-amylase, α-glucosidase, and pancreatic lipase, were investigated in both in vitro and in vivo. Thirty-three constituents including hibiscus acid, 18 phenolic acids, 2 anthocyanins and 12 flavonoids were identified. The anthocyanins content in RE was 21.44 ± 0.68 %, while the contents of chlorogenic acids, rutin and quercetin were 17.76 ± 2.28 %, 0.31 ± 0.01 % and 0.32 ± 0.01 %, respectively. RE inhibited pancreatic lipase in a non-competitive way with an IC50 value of 0.84 mg/mL. Besides, it demonstrated a mixed-type inhibition on both α-glucosidase and α-amylase with IC50 values of 0.59 mg/mL and 1.93 mg/mL, respectively. Fluorescence quenching assays confirmed the binding of RE to the enzyme proteins. Furthermore, rats pre-treated with RE at doses of 50 and 100 mg/kg body weight (bwt) exhibited significant reductions in fat absorption and improvements in fat excretion through feces. Additionally, the in vivo study revealed that RE was effective in suppressing the increase of blood glucose after starch consumption, while its effects on maltose and sucrose consumption were relatively weak.

Excessive Consumption Hibiscus sabdariffa L. Increases Inflammation and Blood Pressure in Male Wistar Rats via High Antioxidant Capacity: The Preliminary Findings

Hibiscus sabdariffa L. (HSL) has high amounts of antioxidants and many beneficial effects in several pathologies. However, few studies describe the possible harmful effects of high concentrations of HSL. Here we evaluate the effect of excessive and chronic consumption of infusions with different percentages of HSL on some oxidative stress markers in serum, and the possible association with inflammation and increased systolic blood pressure (SBP), in healthy rats. A total of 32 male Wistar rats were used to form 4 groups with 8 animals each. Group 1 control (drinking tap water), group 2, 3 and 4, drinking water supplemented with 15, 30 and 60 g/L of HSL calyxes respectively. SBP was evaluated and determinations in serum of the NO₃⁻/NO₂⁻ ratio, glutathione (GSH), total antioxidant capacity (TAC), selenium (Se), TNF-α, IL-1α/IL-1F1, IL-1β, IL-10, extracellular superoxide dismutase (EcSOD), thioredoxin reductase (TrxR) and glutathione peroxidase (GPx) activities, were evaluated. The SBP (p = 0.01), GPx activity, GSH, TAC, Se, TNF-α and EcSOD activities (p ≤ 0.001) and IL-1α/IL-1F1, IL-1β, TrxR and NO₃⁻/NO₂⁻ (p ≤ 0.05), were increased but IL-10 (p < 0.001) was decreased in rats that consumed the 3 and 6% HSL infusions. The excessive and chronic consumption of HSL may increase the TAC that could lead to a proinflammatory state which is associated with hypertension.

Exotic Medicinal Plants Used in Brazil with Diuretic Properties: A Review

Several exotic plants (non-native) are used in Brazilian traditional medicine and are known worldwide for their possible diuretic actions. Among the wide variety of plants, standing out Achillea millefolium L., Camellia sinensis L. Kuntze, Crocus sativus L., Hibiscus sabdariffa Linn., Petroselinum crispum (Mill.) A.W. Hill, Taraxacum officinale (L.) Weber, and Urtica dioica L., whose effects have already been the subject of some scientific study. In addition, we also discussed other exotic species in Brazil used popularly, but that still lack scientific studies, like the species Arctium lappa L., Carica papaya L., Catharanthus roseus (L.) G. Don, Centella asiatica (L.) Urb, Citrus aurantium L., and Persea americana Mill. However, generally, clinical studies on these plants are scarce. In this context, different plant species can be designated for further comprehensive studies, therefore, promoting support for developing an effective medicine to induce diuresis.

Efficacy of Hibiscus sabdariffa on Reducing Blood Pressure in Patients With Mild-to-Moderate Hypertension: A Systematic Review and Meta-Analysis of Published Randomized Controlled Trials

We aimed to assess the efficacy of Hibiscus sabdariffa in patients with mild-to-moderate hypertension or metabolic syndrome (MetS) by comparing it against placebo, antihypertensive drugs, or other herbal products. Four databases were searched for randomized clinical trials (RCTs) examining the efficacy of H. sabdariffa in patients with mild-to-moderate hypertension or hypertension associated with MetS. Data on the change in systolic blood pressure (SBP) and diastolic blood pressure (DBP) were extracted and analyzed using Review Manager Version 5.3. A total of 13 RCTs (1205 participants) were analyzed. Hibiscus sabdariffa significantly reduced both SBP and DBP compared with placebo (mean difference -6.67, P = 0.004 and -4.35 mm Hg, P = 0.02). Subgroup analysis showed that change in SBP and DBP was statistically significant in patients with only hypertension, whereas not significant in patients with hypertension associated with MetS. When H. sabdariffa was compared with active controls (antihypertensive drugs or other herbals), the change in SBP and DBP was not statistically significant (all P > 0.05). Hibiscus sabdariffa is effective in reducing the SBP and DBP in patients with mild-to-moderate hypertension, but was neither effective in those with MetS nor superior to antihypertensive drugs. Further RCTs are required to determine the long-term efficacy of H. sabdariffa and to describe patients who would benefit most from this treatment.

A systematic review and meta-analysis of the effects of Hibiscus sabdariffa on blood pressure and cardiometabolic markers

Context

Hibiscus sabdariffa (hibiscus) has been proposed to affect cardiovascular risk factors.

Objective

To review the evidence for the effectiveness of hibiscus in modulating cardiovascular disease risk markers, compared with pharmacologic, nutritional, or placebo treatments.

Data Sources

A systematic search of the Web of Science, Cochrane, Ovid (MEDLINE, Embase, AMED), and Scopus databases identified reports published up to June 2021 on randomized controlled trials using hibiscus as an intervention for lipid profiles, blood pressure (BP), and fasting plasma glucose levels in adult populations.

Data Extraction

Seventeen chronic trials were included. Quantitative data were examined using a random effects meta-analysis and meta-regression with trial sequential analysis to account for type I and type II errors.

Data Analysis

Hibiscus exerted stronger effects on systolic BP (−7.10 mmHg [95%CI, −13.00, −1.20]; I² = 95%; P = 0.02) than placebo, with the magnitude of reduction greatest in those with elevated BP at baseline. Hibiscus induced reductions to BP similar to that resulting from medication (systolic BP reduction, 2.13 mmHg [95%CI, −2.81, 7.06], I² = 91%, P = 0.40; diastolic BP reduction, 1.10 mmHg [95%CI, −1.55, 3.74], I² = 91%, P = 0.42). Hibiscus also significantly lowered levels of low-density lipoprotein compared with other teas and placebo (−6.76 mg/dL [95%CI, −13.45, −0.07]; I² = 64%; P = 0.05).

Conclusions

Regular consumption of hibiscus could confer reduced cardiovascular disease risk. More studies are warranted to establish an effective dose response and treatment duration.

Systematic Review Registration

PROSPERO registration no. CRD42020167295

Roselle for hypertension in adults

BACKGROUND

Hypertension is considered to be a serious health problem worldwide. Controlling and lowering blood pressure are of significant benefit to people with hypertension because hypertension is a risk factor for stroke, heart disease, and cardiovascular disease. Roselle, the tropical plant Hibiscus sabdariffa, also commonly called sour tea or red tea, has been used as both a thirst-quenching drink and for medicinal purposes.

OBJECTIVES

To assess the effect of Roselle on blood pressure in people with primary hypertension.

SEARCH METHODS

For this update, the Cochrane Hypertension Information Specialist searched the following databases and trials registers for randomised controlled trials (RCTs): the Cochrane Hypertension Specialised Register (to 6 August 2021), Cochrane Central Register of Controlled Trials (CENTRAL; 2021, Issue 7), MEDLINE Ovid (1946 to 5 August 2021), Embase Ovid (1974 to 5 August 2021), ProQuest Dissertations & Theses (to 6 August 2021), Web of Science Clarivate (to 7 August 2021), Food Science and Technology Abstracts Clarivate (to 7 August 2021), the WHO International Clinical Trials Registry Platform (to 6 August 2021), and the US National Institutes of Health Ongoing Trials Register ClinicalTrials.gov (to 6 August 2021). We searched Google Scholar and OpenSIGLE. We also handsearched local and regional Chinese databases: CBM, CMCC, TCMLARS, CNKI, CMAC, and the Index to Chinese Periodical Literature (to 14 September 2020), as well as Thai databases (ThaiJO, CUIR, TDC, CMU e-Theses, TCTR) (to 3 October 2020). There were no language or publication date restrictions.

SELECTION CRITERIA

We sought RCTs evaluating the use of any forms of Roselle with placebo or no treatment in adults with hypertension. Our primary outcome was change in trough and/or peak systolic and diastolic blood pressure (SBP, DBP). Secondary outcomes were withdrawals due to adverse effects, change in pulse pressure, and change in heart rate.

DATA COLLECTION AND ANALYSIS

All search results were managed using Covidence and re-checked for the number of records, inclusion and exclusion of studies with Mendeley reference management software. We used standard methodological procedures expected by Cochrane. Two review authors worked independently in parallel for screening (titles and abstracts, and full reports), data extraction, risk of bias assessment, and assessment of the certainty of the evidence using the GRADE approach. Any disagreements were resolved by discussion or by consultation with the third review author if necessary. We presented mean difference (MD) of change in SBP and DBP with their corresponding 95% confidence interval (CI).

MAIN RESULTS

For this update, only one RCT with a parallel-group design involving 60 participants with type 2 diabetes mellitus fulfilled the inclusion criteria. This study investigated the effect of Roselle extract capsules (total dose of 5600 mg) compared with placebo (lactose) at eight weeks. The study was at low risk of selection bias, performance bias, and detection bias. Conversely, it was at high risk of attrition bias, reporting bias, and other bias (baseline imbalance). We have very little confidence in the effect estimate of Roselle on change-from-baseline in both SBP and DBP between the two groups. The MD of change in SBP was 1.65, 95% CI -7.89 to 11.19 mmHg, 52 participants, very low-certainty evidence. The MD of change in DBP was 4.60, 95% CI -1.38 to 10.58 mmHg, 52 participants, very low-certainty evidence. Our secondary outcomes of withdrawals due to adverse effects, change in pulse pressure, and change in heart rate were not reported. Due to the limited available data, no secondary analyses were performed (subgroup and sensitivity analysis).

AUTHORS' CONCLUSIONS

The evidence is currently insufficient to determine the effectiveness of Roselle compared to placebo for controlling or lowering blood pressure in people with hypertension. The certainty of evidence was very low due to methodological limitations, imprecision, and indirectness. There is a need for rigorous RCTs that address the review question.

A systematic review with meta-analysis on the antihypertensive efficacy of Nigerian medicinal plants

ETHNOPHARMACOLOGICAL RELEVANCE

Despite the promising effects of herbal preparations in lowering blood pressure (BP), hypertension remains a major clinical challenge in Nigeria. The BP-lowering effects of medicinal plants are due to the presence of bioactive compounds.

AIM OF THE STUDY

This meta-analysis presents a precise estimate of the therapeutic benefits of medicinal plants utilized in Nigeria for the management of hypertension in animals and humans.

METHODS

A systematic literature search was performed through Cochrane, PubMed, Science Direct and Scopus databases from inception until February 28, 2021 using search terms related to randomized controlled trials of Nigerian medicinal plants for hypertension. Additional studies were identified through manual search. BP was the main outcome that was measured after the intervention. Meta-analysis was performed using the Review Manager and Meta-Essential.

RESULTS

Nineteen trials comprising of 16 preclinical and 3 clinical studies were enrolled for the meta-analysis. A total number of 16 plants was identified of which H. sabdariffa was the highest reported plant. The plant extracts significantly lowered the systolic blood pressure (SBP) and diastolic blood pressure (DBP) of the hypertensive subjects compared to control. Weighted mean difference (WMD) for SBP (-43.60 mmHg, 95% CI: -63.18, -24.01; p<0.0001) and DBP (-29.50 mmHg, 95 CI: -43.66, -15.34; p<0.0001) was observed for the preclinical studies. For clinical trials, the WMD was -13.98 mmHg, 95 CI: -19.08, -8.88; p<0.00001 for SBP and -10.00 mmHg, 95 CI: -12.22, -7.78; p<0.00001 for DBP. High heterogeneity was observed for the outcome measures of preclinical studies, but not for the clinical studies. The observed substantial heterogeneity in preclinical studies may be linked to methodological shortcomings as evidenced by the results of the risk of bias assessment. There was no evidence of publication bias in animal trials for BP using the funnel plot and Egger's regression test (SBP, p=0.239 and DBP, p=0.112).

CONCLUSIONS

This study provides evidence of medicinal preparations for the treatment of hypertension. A well-conducted trial with methodological rigour and a longer duration of follow-up is required for their effective clinical utilization.

Immunomodulatory and Mechanistic Considerations of Hibiscus sabdariffa (HS) in Dysfunctional Immune Responses: A Systematic Review

Hibiscus sabdariffa calyx (HS) water decoction extract is a commonly consumed beverage with various pharmacological properties. This systematic review examines the possible effect of HS intake on immune mediators. The Scopus and PUBMED databases were searched for all human and animal studies that investigated the effect of HS administration on immune related biomarkers. For each of the immune biomarkers, the mean, standard deviation and number of subjects were extracted for both the HS treated and untreated group. These values were used in the computation of standardized mean difference (SMD). Statistical analysis and forest plot were done with R statistical software (version 3.6.1). Twenty seven (27) studies met the eligibility criteria. Twenty two (22) of the studies were used for the meta-analysis which included a total of 1211 subjects. The meta-analysis showed that HS administration significantly lowered the levels of TNF-α (n=10; pooled SMD: -1.55; 95% CI: -2.43, -0.67; P < 0.01), IL-6 (n=11; pooled SMD:-1.09; 95% CI: -1.77, -0.40; P < 0.01), IL-1β (n=7; pooled SMD:-0.62; 95% CI: -1.25, 0.00; P = 0.05), Edema formation (n=4; pooled SMD: -2.29; 95% CI: -4.47, -0.11; P = 0.04), Monocyte Chemoattractant Protein -1 (n=4; pooled SMD: -1.17; 95% CI: -1.78, -0.57; P < 0.01) and Angiotensin converting enzyme cascade (n=6; pooled SMD: -0.91; 95% CI: -1.57, -0.25; P < 0.01). The levels of IL-10 (n=4; pooled SMD: -0.38; 95% CI: -1.67, 0.91; P = 0.56), Interleukin 8 (n=2; pooled SMD:-0.12; 95% CI: -0.76, 0.51; P = 0.71), iNOS (n=2; pooled SMD:-0.69; 95% CI: -1.60, 0.23 P = 0.14) and C- Reactive Protein (n=4; pooled SMD: 0.05; 95% CI: -0.26, 0.36; P = 0.75), were not significantly changed by HS administration. Some of the results had high statistical heterogeneity. HS may be promising in the management of disorders involving hyperactive immune system or chronic inflammation.

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.

Effect of Different Drying Methods on the Nutritional Value of Hibiscus sabdariffa Calyces as Revealed by NMR Metabolomics

Red mature calyces of Hibiscus sabdariffa were collected from 16 different locations in Meghalaya, India. Samples were processed using shade drying (SD) and tray drying (TD). NMR spectroscopy was used to assess the metabolic composition of the calyces. In this study, 18 polar metabolites were assigned using 1D and 2D NMR spectra, and 10 of them were quantified. Proximate analysis showed that the TD method is more efficient at reducing moisture and maintaining the ash content of the Hibiscus biomass. NMR metabolomics indicates that the metabolite composition significantly differs between SD and TD samples and is more stable in TD plant processing. The differences in post-harvest drying has a greater impact on the metabolite composition of Hibiscus than the plant location.

Aqueous Fraction from Hibiscus sabdariffa Relaxes Mesenteric Arteries of Normotensive and Hypertensive Rats through Calcium Current Reduction and Possibly Potassium Channels Modulation

BACKGROUND/OBJECTIVES

Hibiscus sabdariffa L. (H. sabdariffa (HS)) extract has a vascular relaxant effect on isolated rat thoracic aorta, but data on small resistance arteries, which play an important role on the development of hypertension, are still missing. The purposes of this study were (1) to assess the effect on isolated mesenteric arteries (MA) from normotensive (Wistar and Wistar-Kyoto (WKY)) and spontaneous hypertensive rats (SHR); (2) to elucidate the mechanism(s) of action underling the relaxant effect in light of bioactive components.

METHODS

Vascular effects of HS aqueous fraction (AF) on isolated MA rings, as well as its mechanisms of action, were assessed using the contractility and intracellular microelectrode technique. The patch clamp technique was used to evaluate the effect of HS AF on the L-type calcium current. Extraction and enrichment of AF were carried out using liquid-liquid extraction, and the yield was analyzed using HPLC.

RESULTS

The HS AF induced a concentration-dependent relaxant effect on MA rings of SHR (EC₅₀ = 0.83 ± 0.08 mg/mL), WKY (EC₅₀ = 0.46 ± 0.04 mg/mL), and Wistar rats (EC₅₀ = 0.44 ± 0.08 mg/mL) pre-contracted with phenylephrine (10 µM). In Wistar rats, the HS AF maximum relaxant effect was not modified after endothelium removal or when a guanylate cyclase inhibitor (ODQ, 10 µM) and a selective β2-adrenergic receptor antagonist (ICI-118551, 1 µM) were incubated with the preparation. Otherwise, it was reduced by 34.57 ± 10.66% when vascular rings were pre-contracted with an 80 mM [K+] solution (p < 0.001), which suggests an effect on ionic channels. HS AF 2 mg/mL significantly decreased the peak of the L-type calcium current observed in cardiac myocytes by 24.4%. Moreover, though the vasorelaxant effect of HS, AF was reduced by 27% when the nonselective potassium channels blocker (tetraethylammonium (TEA) 20 mM) was added to the bath (p < 0.01). The extract did not induce a membrane hyperpolarization of smooth muscle cells, which might suggest an absence of a direct effect on background potassium current.

CONCLUSION

These results highlight that the antihypertensive effect of HS probably involves a vasorelaxant effect on small resistance arteries, which is endothelium independent. L-type calcium current reduction contributes to this effect. The results could also provide a link between the vasorelaxant effect and the bioactive compounds, especially anthocyanins.

Insight into the molecular evidence supporting the remarkable chemotherapeutic potential of Hibiscus sabdariffa L

Hibiscus sabdariffa or roselle tea is popular around the globe for its antioxidant capability along with various other health benefits. Besides, it has uses in Ayurvedic and Chinese herbal medicines for the treatment of several diseases. However, the investigation for the anticancer potential of the plant began roughly in the last decade that emerged with encouraging results. Both crude extracts and pure compounds of the plant were reported to induce chemoprevention, selective cytotoxicity, cell cycle arrest, apoptosis, autophagy and anti-metastasis effects in varied types of human cancer cells. The plant contains a high quantity of polyphenolic compounds and at least two of them were proven to induce potent anticancer effects. Although, the molecular mechanism underlying the anticancer activity was roughly estimated in several studies. The present review aimed to assemble all ambiguous information to report the molecular evidence establishing the potent anticancer activity of Hibiscus sabdariffa and its implication for cancer therapy. This study suggests that Hibiscus sabdariffa is an ideal candidate to investigate its role as a herbal supplement for cancer prevention and treatment. With excellent safety and tolerability record, polyphenolic compounds from the plant need better designed clinical trials.

Potential Application of Tetrapleura tetraptera and Hibiscus sabdariffa (Malvaceae) in Designing Highly Flavoured and Bioactive Pito with Functional Properties

Sorghum beer (pito) is an indigenous alcoholic beverage peculiar to northern Ghana and parts of other West African countries. It is overwhelmed with calories, essential amino acids (such as lysine, etc.), B-group vitamins, and minerals. In recent years, there has been a growing demand for highly flavoured yet functional pito in Ghana; however, the local producers lack the prerequisite scientific expertise in designing such products. We propose the utilization of Tetrapleura tetraptera (TT) and Hibiscus sabdariffa (HS) as cheap and readily available materials in designing functional flavoured pito. The addition of TT and HS would not alter the fermentation profile but rather augment the starter with nutrients, thus improving the fermentation performance and shelf life of the final pito. In vitro and in vivo studies provide substantive evidence of antioxidant, nephro- and hepato-protective, renal/diuretic effect, anticholesterol, antidiabetic, and antihypertensive effects among others of the TT and HS, hence enriching the pito with health-promoting factors and consequently boosting the health of the consumer. Herein, we summarise the phytochemical, biological, pharmacological, and toxicological aspects of TT and HS as well as the technology involved in brewing the novel bioactive-flavoured pito. In addition, we also report the incidence of heavy metal in conventional pito.

Antihypertensive phytocomplexes of proven efficacy and well-established use: Mode of action and individual characterization of the active constituents

Hypertension has become the leading risk factor for worldwide cardiovascular diseases. Conventional pharmacological treatment, after both dietary and lifestyle changes, is generally proposed. In this review, we present the antihypertensive properties of phytocomplexes from thirteen plants, long ago widely employed in ethnomedicines and, in recent years, increasingly evaluated for their activity in vitro and in vivo, also in humans, in comparison with synthetic drugs acting on the same systems. Here, we focus on the demonstrated or proposed mechanisms of action of such phytocomplexes and of their constituents proven to exert cardiovascular effects. Almost seventy phytochemicals are described and scientifically sound pertinent literature, published up to now, is summarized. The review emphasizes the therapeutic potential of these natural substances in the treatment of the 'high normal blood pressure' or 'stage 1 hypertension', so-named according to the most recent European and U.S. guidelines, and as a supplementation in more advanced stages of hypertension, however needing further validation by clinical trial intensification.

The efficacy of sour tea (Hibiscus sabdariffa L.) on selected cardiovascular disease risk factors: A systematic review and meta-analysis of randomized clinical trials

This study sought to summarize clinical evidence of sour tea (Hibiscus sabdariffa L.) administration on cardiovascular disease risk factors. PubMed, Scopus, Institute for Scientific Information Web of Science, and Google Scholar were systematically searched from inception to June 2019 to identify randomized clinical trials, which assessed the effect of sour tea consumption on lipid profiles, fasting plasma glucose, and blood pressure in adult populations. Mean and standard deviation for each parameter were extracted to calculate effect size. Cochrane Collaboration tools were used to evaluate risk of bias assessment. A total of seven randomized clinical trials consisting 362 participants were included in the meta-analysis. Pooled effect size demonstrated that sour tea consumption significantly reduces fasting plasma glucose (-3.67 mg/dl, 95% confidence interval, CI [-7.07, -0.27]; I² = 37%), systolic blood pressure (-4.71 mmHg, 95% CI [-7.87, -1.55]; I² = 53%), and diastolic blood pressure (-4.08 mmHg, 95% CI [-6.48, -1.67]; I² = 14%). Although no significant effect was observed on triacylglycerol, total cholesterol, and high-density lipoprotein cholesterol following sour tea consumption, a trend toward a significant reduction was found in low-density lipoprotein cholesterol serum concentrations (p = 0.08). This systematic review and meta-analysis suggests that sour tea consumption could have beneficial effect in controlling glycemic status and blood pressure among adult population.

Effect of hibiscus sabdariffa on blood pressure in patients with stage 1 hypertension

Using different drug regimens has been proved to have effective effects on lowering blood pressure, but the adverse effects of long-term usage such medications is evident. According to recent trend in suing herbal and traditional medicines, researchers have been focused on evaluating the effect of different herbals on managing hypertension. The aim of the present study is the evaluation of the antihypertensive effect one of these herbs, sour tea (Hibiscus sabdariffa), on stage one hypertension. Patients with stage one hypertension who were diagnosed by a cardiologist has been included in the present clinical trial after giving informed consent. The patients were divided into two groups. The control and case group received the same lifestyle and dietary advices for controlling blood pressure. The case group received two standard cup of sour tea every morning for 1 month. The blood pressure of both groups was documented at baseline and at the end of the study and the results were analyzed using SPSS software. A total of 46 patients participated in this study and there was no significant difference in terms of age and body mass index between groups. There was a significant reduction in systolic blood pressure in both groups, but the mean reduction in systolic and diastolic blood pressure was significantly higher in the case group (P = 0.004 and P < 0.001, respectively). Using H. sabdariffa as sour tea two times a day can be effective in managing blood pressure in stage one hypertension along with lifestyle and dietary modification.

Myocardial Protection from Ischemia-Reperfusion Damage by the Antioxidant Effect of Hibiscus sabdariffa Linnaeus on Metabolic Syndrome Rats

Cardiovascular diseases (CVD) constitute one of the most prevalent health problems worldwide, being strongly associated with metabolic syndrome (MS). Oxidative stress (OS) is present in both CVD and MS. Infusions of Hibiscus sabdariffa Linnaeus (HSL) have antioxidant properties and could therefore decrease the presence of OS in these diseases. The aim of this study was to evaluate myocardial protection during ischemia/reperfusion due to the antioxidant effect of HSL infusion (3%) on a MS rat model induced by the administration of 30% sucrose in drinking water. We determined in control, MS, and MS + HSL rat hearts (n = 6 per group) cardiac mechanical performance (CMP), coronary vascular resistance (CVR), and activities of manganese and copper/zinc superoxide dismutases (Mn and Cu/Zn-SOD), peroxidases, glutathione peroxidase (GPx), catalase (CAT), glutathione s-transferase (GST), glutathione reductase (GR), and glutathione (GSH). We also determined lipoperoxidation (LPO), total antioxidant capacity (TAC), and the nitrate/nitrite ratio (NO₃⁻/NO₂⁻). The treatment with the HSL infusion restored the CMP (p = 0.01) and CVR (p = 0.04) and increased the Mn- (p = 0.02), Cu/Zn-SOD (p = 0.05), peroxidases (p = 0.04), GST (p = 0.02) activity, GHS (p = 0.02), TAC (p = 0.04), and NO₃⁻/NO₂⁻ (p = 0.01) and decreased the LPO (p = 0.02) in the heart of MS rats undergoing ischemia/reperfusion. The results suggest that the treatment with an infusion from HSL calices protects the cardiac function from damage by ischemia and reperfusion through the antioxidant activities of the substances it possesses. It favors antioxidant enzymatic activities and nonenzymatic antioxidant capacity.

Hibiscus acid from Hibiscus sabdariffa (Malvaceae) has a vasorelaxant effect on the rat aorta

Hibiscus sabdariffa (Malvaceae) is a plant that is widely recognised for its antihypertensive properties; however the constituent(s) responsible for this biological activity are presently unknown. The aim of this study was to identify the potential compounds that are responsible for the vasorelaxant activity of H. sabdariffa. Thereafter, the mechanisms involved in producing the vasorelaxation were investigated. The plant was extracted consecutively with hexane, ethyl acetate and methanol. The methanolic extract was subjected to bioassay-guided fractionation in order to isolate pure compounds that possessed vasorelaxant activity. The vascular effects of the pure compounds were studied on the rat aorta in vitro using myography techniques. Hibiscus acid produced a concentration-dependent relaxation of the rat aorta pre-contracted with either phenylephrine (3 μM) or KCl (60 mM), irrespective of the presence of the endothelium. When the tissue was pre-contracted with phenylephrine, the concentration required to produce 50% relaxation (IC₅₀), was 0.09 ± 0.01 mg/ml. Hibiscus acid had no effect on the phasic contraction induced by phenylephrine in Ca²⁺-free physiological solution; but it did affect the component of the contraction that is due to Ca²⁺ influx. In parallel studies, garcinia acid, a diastereoisomer of hibiscus acid, was found to have an almost identical vasorelaxant effect. The vasorelaxant action of both compounds is most likely due to the inhibition of Ca²⁺ influx via voltage-dependent Ca²⁺ channels.

Beneficial Effects of Natural Bioactive Compounds from Hibiscus sabdariffa L. on Obesity

Obesity is a condition associated with the accumulation of excess fat in the body, energy imbalance, lipogenesis, etc., which increases adipose tissue mass through adipogenesis and poses a health risk. Its prevalence has become an economic burden to the health care system and the world at large. One of the alternatives to tackling obesity involves the use of bioactive compounds. We critically examined the effects of Hibiscus sabdariffa extract (HSE) on various parameters associated with the development of obesity such as; the effect of HSE on body weight, the effect of HSE on lipid accumulation, cholesterol metabolism and plasma parameters, the inhibitory effect of HSE on pancreatic lipase, and the effect of HSE on adipocyte differentiation/adipogenesis. This review has gathered reports on the various anti-obesity effects of H. sabdariffa bioactive compounds in cell and animal models, as well as in humans. Available toxicology information on the consumption of H. sabdariffa revealed that its toxicity is dose-dependent and may cause an adverse effect when administered over a long period of time. Reports have shown that H. sabdariffa derived bioactive compounds are potent in the treatment of obesity with an evident reduction in body weight, inhibition of lipid accumulation and suppression of adipogenesis through the PPARγ pathway and other transcriptional factors.

Medicinal plants used for hypertension treatment by folk healers in Songkhla province, Thailand

ETHNOPHARMACOLOGICAL RELEVANCE

Hypertension is the most dominant risk factor for the development of cardiovascular, kidney, and eye diseases. In Thailand, illness and hospitalisation in the modern public health system due to high blood pressure is increasing. However, some Thai people have turned their attention to the use of herbal medicines for healthcare. Therefore, this study aimed (1) to study the folk knowledge of hypertension treatment and (2) to study plant utilisation in the treatment of high blood pressure by Songkhla folk healers.

MATERIALS AND METHODS

Field surveys and semi-structured interviews about theories of disease, principles of healing, and herbal usage (plant species, parts used, preparation, and application methods) were gathered. The data were analysed by descriptive statistics. The literatures regarding medicinal plants used in any traditional medicine, antihypertension activity, and toxicity was reviewed.

RESULTS

Most healers believed that hypertension was caused by the disorder of fire and wind elements in the body. The medicinal plants containing hot and mild tastes, which had the potential for treating problems in the wind element, were applied. A total of 62 species were used for hypertension treatment. Most plants were in the Asteraceae, Piperaceae, Rutaceae, or Zingiberaceae family (4 species each). Herbal medicines were preferred to be prepared by boiling (78%) and consumed by drinking 1 teacup before 3 meals each day (26%). Piper retrofractum and Cleome viscosa had the greatest Frequency of Citation (FC = 6, n = 14). Thirty-seven species have been reported for use in traditional medicine. Twenty-four and 46 species have already been investigated for antihypertension activity and toxicity, respectively.

CONCLUSION

Identifying medicinal plants that have been tested by experienced folk doctors would provide an opportunity for people to choose and consume local herbs that are easy to access in their local area. However, the remaining plants that have not been studied for antihypertension activity and toxicity should be further analysed to confirm their efficacy.

Antihypertensive Effects of Roselle-Olive Combination in L-NAME-Induced Hypertensive Rats

This study aimed to evaluate the antihypertensive efficacy of a new combination therapy of Hibiscus sabdariffa and Olea europaea extracts (2 : 1; Roselle-Olive), using N(G)-nitro-L-arginine-methyl ester- (L-NAME-) induced hypertensive model. Rats received L-NAME (50 mg/kg/day, orally) for 4 weeks. Concurrent treatment with Roselle-Olive (500, 250, and 125 mg/kg/day for 4 weeks) resulted in a dose-dependent decrease in both systolic and diastolic blood pressure, reversed the L-NAME-induced suppression in serum nitric oxide (NO), and improved liver and kidney markers, lipid profile, and oxidative status. Furthermore, Roselle-Olive significantly lowered the elevated angiotensin-converting enzyme activity (ACE) and showed a marked genoprotective effect against oxidative DNA damage in hypertensive rats. Roselle-Olive ameliorated kidney and heart lesions and reduced aortic media thickness. Real-time PCR and immunohistochemistry showed an enhanced endothelial nitric oxide synthase (eNOS) gene and protein expression in both heart and kidney of Roselle-Olive-treated rats. To conclude, our data revealed that Roselle-Olive is an effective combination in which H. sabdariffa and O. europaea synergistically act to control hypertension. These effects are likely to be mediated by antioxidant and genoprotective actions, ACE inhibition, and eNOS upregulation by Roselle-Olive constituents. These findings provide evidences that Roselle-Olive combination affords efficient antihypertensive effect with a broad end-organ protective influence.

Polyphenols reported to shift APAP-induced changes in MAPK signaling and toxicity outcomes

Due to its widespread availability, acetaminophen (APAP) is the leading cause for drug-induced liver injury in many countries including United States and United Kingdom. When used as recommended, APAP is relatively safe. However, in overdose cases, increased metabolism of APAP to N-acetyl-para-benzoquinoneimine (NAPQI), a reactive metabolite, leads to glutathione (GSH) depletion, oxidative stress, and cellular injury. Throughout this process, a variety of factors play important roles in propagating toxicity, including c-Jun N-terminal kinase (JNK), a member of the mitogen-activated protein kinase (MAPK) family. Because of its involvement in multiple cellular processes, biomarkers associated with MAPK signaling have generated interest as a mechanistic target for protecting against APAP-induced liver injury and hepatocellular injury, in general. This review summarizes mechanistic details by which natural products, specifically those containing polyphenolic moieties, are capable of attenuating APAP-induced toxicity, at least in part through an ability to modulate MAPKs. These compounds include carnosic acid, chlorogenic acid, davallialactone, extracts from Hibiscus sabdariffa, quercetin-based compounds, and resveratrol. Despite variations in the experimental designs across these studies, common pathways and biomarkers were implicated in cytoprotection when polyphenolic compounds were given with APAP, such as enhanced antioxidant gene expression and reversal of APAP-induced changes in oxidative stress markers and MAPK signaling. Overall, an emphasis should be placed on method standardization for future studies if we are to gain a more in-depth understanding of how polyphenolic moieties contribute to cytoprotection during an APAP overdose event.

The response of male and female rats to a high-fructose diet during adolescence following early administration ofHibiscus sabdariffaaqueous calyx extracts

Metabolic syndrome is linked to the consumption of fructose-rich diets. Nutritional and pharmacological interventions perinatally can cause epigenetic changes that programme an individual to predispose or protect them from the development of metabolic diseases later.Hibiscus sabdariffa(HS) reportedly has anti-obesity and hypocholesterolaemic properties in adults. We investigated the impact of neonatal intake of HS on the programming of metabolism by fructose. A total of 85 4-day-old Sprague Dawley rats were divided randomly into three groups. The control group (n=27, 12 males, 15 females) received distilled water at 10 ml/kg body weight. The other groups received either 50 mg/kg (n=30, 13 males, 17 females) or 500 mg/kg (n=28, 11 males, 17 females) of an HS aqueous calyx extract orally till postnatal day (PND) 14. There was no intervention from PND 14 to PND 21 when the pups were weaned. The rats in each group were then divided into two groups; one continued on a normal diet and the other received fructose (20% w/v) in their drinking water for 30 days. The female rats that were administered with HS aqueous calyx extract as neonates were protected against fructose-induced hypertriglyceridaemia and increased liver lipid deposition. The early administration of HS resulted in a significant (P⩽0.05) increase in plasma cholesterol concentrations with or without a secondary fructose insult. In males, HS prevented the development of fructose-induced hypercholesterolaemia. The potential beneficial and detrimental effects of neonatal HS administration on the programming of metabolism in rats need to be considered in the long-term well-being of children.

Cardioprotective Effect of Aloe vera Biomacromolecules Conjugated with Selenium Trace Element on Myocardial Ischemia-Reperfusion Injury in Rats

The present study was undertaken to evaluate the cardioprotection potential and underlying molecular mechanism afforded by a selenium (Se) polysaccharide (Se-AVP) from Aloe vera in the ischemia-reperfusion (I/R) model of rats in vivo. Myocardial I/R injury was induced by occluding the left anterior descending coronary artery (LAD) for 30 min followed by 2-h continuous reperfusion. Pretreatment with Se-AVP (100, 200, and 400 mg/kg) attenuated myocardial damage, as evidenced by reduction of the infarct sizes, increase in serum and myocardial endogenous antioxidants (superoxide dismutase (SOD), glutathione peroxidase (GSH), and catalase (CAT)), and decrease in the malondialdehyde (MDA) level in the rats suffering I/R injury. This cardioprotective activity afforded by Se-AVP is further supported by the decreased levels of cardiac marker enzymes creatine kinase (CK) and lactate dehydrogenase (LDH), as well as the rise of myocardial Na⁺-K⁺-ATPase and Ca²⁺-Mg²⁺-ATPase activities in I/R rats. Additionally, cardiomyocytic apoptosis was measured by terminal-deoxynucleotidyl transferase-mediated nick end labeling (TUNEL) staining and the result showed that the percent of TUNEL-positive cells in myocardium of Se-AVP-treated groups was lower than I/R rats. In conclusion, we clearly demonstrated that Se-AVP had a protective effect against myocardial I/R injury in rats by augmenting endogenous antioxidants and protecting rat hearts from oxidative stress-induced myocardial apoptosis.

Does consumption of an aqueous extract of Hibscus sabdariffa affect renal function in subjects with mild to moderate hypertension?

Hibiscus sabdariffa (HS) has been traditionally used as a herbal medicine in Nigeria mainly because of its antihypertensive action. In view of the recent increase in the prevalence of renal failure, we have investigated the effect of HS consumption on renal function in Nigerians with mild to moderate hypertension. A total of 78 newly diagnosed but untreated subjects with mild to moderate hypertension attending the medical outpatients unit of Enugu State University Teaching Hospital (Enugu, Nigeria) were recruited for the study. These subjects were randomly divided into three equally sized groups that received HS or lisinopril (treatment groups) or placebo (control group), once daily for 4 weeks. Indices of renal function (urine volume and creatinine clearance) were measured at baseline and weekly throughout the study period. HS and lisinopril significantly increased (P < 0.001) urine volume compared to placebo, and HS significantly (P < 0.001) increased urine volume more than lisinopril. HS significantly increased (P < 0.001) creatinine clearance compared to placebo whereas lisinopril did not. These results indicate that HS consumption improved indices of renal function in our study population of Nigerians with mild to moderate hypertension.

Effects of aqueous extract of Hibiscus sabdariffa on the renin-angiotensin-aldosterone system of Nigerians with mild to moderate essential hypertension: A comparative study with lisinopril

Objectives:

The present study investigated the effects of aqueous extract of Hibiscus sabdariffa (HS) on the three basic components of renin-angiotensin-aldosterone system: Plasma renin, serum angiotensin-converting enzyme (ACE), and plasma aldosterone (PA) in mild to moderate essential hypertensive Nigerians and compared with that of lisinopril, an ACE inhibitor.

Materials and Methods:

A double-blind controlled randomized clinical study was used. Seventy-eight newly diagnosed but untreated mild to moderate hypertensive subjects attending Medical Outpatients Clinic of Enugu State University Teaching Hospital, Enugu were recruited for the study. Those in Group A received placebo (150 mg/kg/day), Group B were given lisinopril (10 mg once daily) while those in Group C received aqueous extract of HS (150 mg/kg/day). After 4 weeks of treatment, the levels of plasma renin, serum ACE, and PA were determined.

Results:

HS and lisinopril significantly (P < 0.001) reduced PA compared to placebo by 32.06% and 30.01%, respectively. Their effects on serum ACE and plasma renin activity (PRA) were not significant compared to placebo; they reduced ACE by 6.63% and 5.67% but increased plasma PRA by 2.77% and 5.36%, respectively.

Conclusion:

HS reduced serum ACE and PA in mild to moderate hypertensive Nigerians with equal efficacy as lisinopril. These actions are possibly due to the presence of anthocyanins in the extract.

Effect of sour tea (Hibiscus sabdariffa L.) on arterial hypertension: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Hibiscus sabdariffa L. is a tropical wild plant rich in organic acids, polyphenols, anthocyanins, polysaccharides, and volatile constituents that are beneficial for the cardiovascular system. Hibiscus sabdariffa beverages are commonly consumed to treat arterial hypertension, yet the evidence from randomized controlled trials (RCTs) has not been fully conclusive. Therefore, we aimed to assess the potential antihypertensive effects of H. sabdariffa through systematic review of literature and meta-analysis of available RCTs.

METHODS

The search included PUBMED, Cochrane Library, Scopus, and EMBASE (up to July 2014) to identify RCTs investigating the efficacy of H. sabdariffa supplementation on SBP and DBP values. Two independent reviewers extracted data on the study characteristics, methods, and outcomes. Quantitative data synthesis and meta-regression were performed using a fixed-effect model, and sensitivity analysis using leave-one-out method. Five RCTs (comprising seven treatment arms) were selected for the meta-analysis. In total, 390 participants were randomized, of whom 225 were allocated to the H. sabdariffa supplementation group and 165 to the control group in the selected studies.

RESULTS

Fixed-effect meta-regression indicated a significant effect of H. sabdariffa supplementation in lowering both SBP (weighed mean difference -7.58 mmHg, 95% confidence interval -9.69 to -5.46, P < 0.00001) and DBP (weighed mean difference -3.53 mmHg, 95% confidence interval -5.16 to -1.89, P < 0.0001). These effects were inversely associated with baseline BP values, and were robust in sensitivity analyses.

CONCLUSION

This meta-analysis of RCTs showed a significant effect of H. sabdariffa in lowering both SBP and DBP. Further well designed trials are necessary to validate these results.

Anti-hypertensive Herbs and their Mechanisms of Action: Part I

The use of herbal therapies for treatment and management of cardiovascular diseases (CVDs) is increasing. Plants contain a bounty of phytochemicals that have proven to be protective by reducing the risk of various ailments and diseases. Indeed, accumulating literature provides the scientific evidence and hence reason d'etre for the application of herbal therapy in relation to CVDs. Slowly, but absolutely, herbal remedies are being entrenched into evidence-based medical practice. This is partly due to the supporting clinical trials and epidemiological studies. The rationale for this expanding interest and use of plant based treatments being that a significant proportion of hypertensive patients do not respond to Modern therapeutic medication. Other elements to this equation are the cost of medication, side-effects, accessibility, and availability of drugs. Therefore, we believe it is pertinent to review the literature on the beneficial effects of herbs and their isolated compounds as medication for treatment of hypertension, a prevalent risk factor for CVDs. Our search utilized the PubMed and ScienceDirect databases, and the criterion for inclusion was based on the following keywords and phrases: hypertension, high blood pressure, herbal medicine, complementary and alternative medicine (CAM), nitric oxide, vascular smooth muscle cell (VSMC) proliferation, hydrogen sulfide, nuclear factor kappa-B, oxidative stress, and epigenetics/epigenomics. Each of the aforementioned keywords was co-joined with herb in question, and where possible with its constituent molecule(s). In this first of a two-part review, we provide a brief introduction of hypertension, followed by a discussion of the molecular and cellular mechanisms. We then present and discuss the plants that are most commonly used in the treatment and management of hypertension.

Hibiscus sabdariffa Leaf Extract Inhibits Human Prostate Cancer Cell Invasion via Down-Regulation of Akt/NF-kB/MMP-9 Pathway

Hibiscus sabdariffa leaf has been previously shown to possess hypoglycemic, hypolipidemic, and antioxidant effects, and induce tumor cell apoptosis. However, the molecular mechanisms involved in the anticancer activity of H. sabdariffa leaf extract (HLE) are poorly understood. The object of the study was to examine the anti-invasive potential of HLE. First, HLE was demonstrated to be rich in polyphenols. The results of wound-healing assay and in vitro transwell assay revealed that HLE dose-dependently inhibited the migration and invasion of human prostate cancer LNCaP (lymph node carcinoma of the prostate) cells under non-cytotoxic concentrations. Our results further showed that HLE exerted an inhibitory effect on the activity and expressions of matrix metalloproteinase-9 (MMP-9). The HLE-inhibited MMP-9 expression appeared to be a consequence of nuclear factor-kappaB (NF-κB) inactivation because its DNA-binding activity was suppressed by HLE. Molecular data showed all these influences of HLE might be mediated via inhibition of protein kinase B (PKB, also known as Akt)/NF-κB/MMP-9 cascade pathway, as demonstrated by the transfection of Akt1 overexpression vector. Finally, the inhibitory effect of HLE was proven by its inhibition on the growth of LNCaP cells and the expressions of metastasis-related molecular proteins in vivo. These findings suggested that the inhibition of MMP-9 expression by HLE may act through the suppression of the Akt/NF-κB signaling pathway, which in turn led to the reduced invasiveness of the cancer cells.

Anthocyanin-rich extract from Hibiscus sabdariffa calyx counteracts UVC-caused impairments in rats

CONTEXT

Ultraviolet radiation (UV) was reported to cause oxidative stress. Hibiscus sabdariffa L. (Malvaceae) calyx is commonly used in traditional Asian and African medicines and possesses strong antioxidant capacity due to its anthocyanin (ANTH) content.

OBJECTIVE

This study researched the possible protective role of Hibiscus sabdariffa calyx extract (HSCE) in UVC exposure of rats.

MATERIAL AND METHODS

Levels of serum enzymes, renal function tests, and some oxidant/antioxidant biomarkers of skin, lens, and retina tissues were monitored. Rats were exposed to UVC 4 h daily for 40 d and simultaneously received HSCE containing 2.5, 5, and 10 mg doses of ANTH in drinking water.

RESULTS

Significant (p < 0.05) increases in the levels of serum aminotransferases, lactate dehydrogenase, urea, creatinine, and uric acid were noted after UVC exposure. In skin, lens, and retina tissues, total oxidant status, oxidative stress index, lipid peroxidation, and protein oxidation escalated markedly (p < 0.05) whereas total antioxidant status, reduced glutathione, and superoxide dismutase decreased dramatically (p < 0.05) related to UVC. Co-administration of HSCE with each ANTH dose significantly (p < 0.05) reversed aforementioned parameters (except total oxidant status) almost in all tissues. The LD50 of HSCE in rats was determined to be above 5000 mg/kg.

DISCUSSION AND CONCLUSION

Our data revealed that HSCE has a remarkable potential to counteract UVC-caused impairments, probably through its antioxidant and free radical-defusing effects. Therefore, HSCE could be useful against some cutaneous and ocular diseases in which UV and oxidative stress have a role in the etiopathogenesis.

Physicochemical properties and antimicrobial activity of Roselle (Hibiscus sabdariffa L.)

BACKGROUND

The therapeutic action of a plant depends on its chemical constituents. In this study, experiments were carried out in order to evaluate the effect of extraction conditions on the antioxidative and antimicrobial activities of Roselle (Hibiscus sabdariffa L.).

RESULTS

Roselle was found to be rich in malic acid, anthocyanins, ascorbic acid and minerals, especially Ca and Fe, but low in glucose. More than 18 volatile compounds were identified by gas chromatography and gas chromatography-mass spectrometry. This herb, which is rich in phenolic compounds and displays DPPH radical scavenging activity, could be a good source of natural antioxidants. The antimicrobial activity of the Roselle water and ethanol extracts was tested with Bacillus subtilis (ATCC6633), Staphylococcus aureus (ATCC6538) and Escherichia coli (ATCC 8739). The inhibition of the Roselle ethanol extract against B. subtilis and S. aureus was slightly higher than that of water extract but this difference was not significant. However, E. coli was strongly inhibited by the Roselle water extract at concentrations of 25 and 50 mg mL(-1) as determined by a paper disc method.

CONCLUSION

The obtained results indicated that antioxidant and antimicrobial activity was related to different methods of extraction and Roselle extracts could be a source of therapeutically useful products.

Insulin secretion enhancing activity of roselle calyx extract in normal and streptozotocin-induced diabetic rats

Background and Objective:

Our recent study revealed the antihyperglycemic activity of an ethanolic extract of roselle calyxes (Hibiscus sabdariffa) in diabetic rats. The present study had, therefore, an objective to investigate the mechanism underlying this activity.

Materials and Methods:

Male Sprague Dawley rats were induced to be diabetes by intraperitoneal injection of 45 mg/kg streptozotocin (STZ). Normal rats as well as diabetic rats were administered with the ethanolic extract of H. sabdariffa calyxes (HS-EE) at 0.1 and 1.0 g/kg/day, respectively, for 6 weeks. Then, blood glucose and insulin levels, at basal and glucose-stimulated secretions, were measured. The pancreas was dissected to examine histologically.

Results:

HS-EE 1.0 g/kg/day significantly decreased the blood glucose level by 38 ± 12% in diabetic rats but not in normal rats. In normal rats, treatment with 1.0 g/kg HS-EE increased the basal insulin level significantly as compared with control normal rats (1.28 ± 0.25 and 0.55 ± 0.05 ng/ml, respectively). Interestingly, diabetic rats treated with 1.0 g/kg HS-EE also showed a significant increase in basal insulin level as compared with the control diabetic rats (0.30 ± 0.05 and 0.15 ± 0.01 ng/ml, respectively). Concerning microscopic histological examination, HS-EE 1.0 g/kg significantly increased the number of islets of Langerhans in both normal rats (1.2 ± 0.1 and 2.0 ± 0.1 islet number/10 low-power fields (LPF) for control and HS-EE treated group, respectively) and diabetic rats (1.0 ± 0.3 and 3.9 ± 0.6 islet number/10 LPF for control and HS-EE treated group, respectively).

Conclusion:

The antidiabetic activity of HS-EE may be partially mediated via the stimulating effect on insulin secretion.

Toxicity studies of the water extract from the calyces of Hibiscus sabdariffa L. in rats

Acute and chronic toxicities of the water extract from calyces of Hibiscus sabdariffa were studied in male and female rats. After 14 days of a single oral administration of test substance 5,000 mg/kg body weight, measurement of the body and organ weights, necropsy and health monitoring were performed. No signs and differences of the weights or behaviour compared to the control rats were observed. The results indicated that the single oral administration of H. sabdariffa extract in the amount of 5,000 mg/kg body weight does not produce acute toxicity. The chronic toxicity was determined by oral feeding both male and female rats daily with the extract at the doses of 50, 100, and 200 mg/kg body weight for 270 days. The examinations of signs, animal behaviour and health monitoring showed no defects in the test groups compared to the control groups. Both test and control groups (day 270th) and satellite group (day 298th) were analysed by measuring their final body and organ weights, taking necropsy, and examining haematology, blood clinical chemistry, and microanatomy. Results showed no differences from the control groups. Overall, our study demonstrated that an oral administration of H. sabdariffa extract at the doses of 50, 100 and 200 mg/kg body weight for 270 days does not cause chronic toxicity in rat.

Hibiscus sabdariffa L. in the treatment of hypertension and hyperlipidemia: a comprehensive review of animal and human studies

The effectiveness of Hibiscus sabdariffa L. (HS) in the treatment of risk factors associated with cardiovascular disease is assessed in this review by taking a comprehensive approach to interpreting the randomized clinical trial (RCT) results in the context of the available ethnomedical, phytochemical, pharmacological, and safety and toxicity information. HS decoctions and infusions of calyxes, and on occasion leaves, are used in at least 10 countries worldwide in the treatment of hypertension and hyperlipidemia with no reported adverse events or side effects. HS extracts have a low degree of toxicity with a LD50 ranging from 2,000 to over 5,000mg/kg/day. There is no evidence of hepatic or renal toxicity as the result of HS extract consumption, except for possible adverse hepatic effects at high doses. There is evidence that HS acts as a diuretic, however in most cases the extract did not significantly influence electrolyte levels. Animal studies have consistently shown that consumption of HS extract reduces blood pressure in a dose dependent manner. In RCTs, the daily consumption of a tea or extract produced from HS calyxes significantly lowered systolic blood pressure (SBP) and diastolic blood pressure (DBP) in adults with pre to moderate essential hypertension and type 2 diabetes. In addition, HS tea was as effective at lowering blood pressure as the commonly used blood pressure medication Captropril, but less effective than Lisinopril. Total cholesterol, low-density lipoprotein cholesterol (LDL-C), and triglycerides were lowered in the majority of normolipidemic, hyperlipidemic, and diabetic animal models, whereas high-density lipoprotein cholesterol (HDL-C) was generally not affected by the consumption of HS extract. Over half of the RCTs showed that daily consumption of HS tea or extracts had favorable influence on lipid profiles including reduced total cholesterol, LDL-C, triglycerides, as well as increased HDL-C. Anthocyanins found in abundance in HS calyxes are generally considered the phytochemicals responsible for the antihypertensive and hypocholesterolemic effects, however evidence has also been provided for the role of polyphenols and hibiscus acid. A number of potential mechanisms have been proposed to explain the hypotensive and anticholesterol effects, but the most common explanation is the antioxidant effects of the anthocyanins inhibition of LDL-C oxidation, which impedes atherosclerosis, an important cardiovascular risk factor. This comprehensive body of evidence suggests that extracts of HS are promising as a treatment of hypertension and hyperlipidemia, however more high quality animal and human studies informed by actual therapeutic practices are needed to provide recommendations for use that have the potential for widespread public health benefit.

Effect of extract of Hibiscus on the ultrastructure of the testis in adult mice

Hibiscus sabdariffa extract is a popular beverage in many tropical and sub-tropical countries. Although, Hibiscus tea is known for its medicinal effects for thousands of years, scientific evidence of its systemic safety is very limited. The current study aimed to assess the potential adverse effects of H. sabdariffa extract on sperm morphology and testicular ultrastructure of albino mice. Thirty adult male albino mice were divided into three equal groups and were given: (a) distilled water, (b) cold Hibiscus aqueous extract, and (c) boiled Hibiscus aqueous extract. Hibiscus extract was administered orally daily for 4 weeks in a dose of 200 mg/kg body weight/mouse. Twenty-four hours after the last treatment, mice were decapitated and the testes and epididymides were excised and processed for transmission electron microscopy to assess ultrastructural and sperm abnormalities. The results clearly demonstrate that aqueous extracts from dried calyx of H. sabdariffa, either cold or boiled, alter normal sperm morphology and testicular ultrastructure and adversely influence the male reproductive fertility in albino mice. The current data suggest that Hibiscus extract should be consumed with caution, and reasonable estimates of the human risk associated with its consumption should be provided.

Long-term ingestion of Hibiscus sabdariffa calyx extract enhances myocardial capillarization in the spontaneously hypertensive rat

The effects of Hibiscus sabdariffa (HS) in lowering blood pressure in human and animal hypertension have been documented. This study investigated the effect of the water extract of the dried calyx of HS and Hibiscus anthocyanins (HAs) on left ventricular myocardial capillary length and surface area in spontaneously hypertensive rats (SHRs). Twelve-week-old male SHRs were divided into eight groups (six rats in each group). Three groups were given three doses; 10%, 15% and 20% of the water extract of HS in lieu of drinking water for 10 consecutive weeks (HS10, HS15 and HS20) with one group kept as control (C). Another three groups were given three doses of the HAs orally at doses of 50, 100 and 200 mg/kg for five consecutive days with one group kept as a control (C). Systolic (SBP) and diastolic (DBP) blood pressures, as well as heart rate (HR), were measured weekly. After the experimental protocols, the left ventricles (LV) of all rats were obtained. Capillary surface area density and length density were determined by unbiased sterological methods on 3 μm LV tissue samples from perfusion-fixed hearts. HS ingestion significantly reduced SBP, DBP and LV mass in a dose-dependent fashion but did not affect the HR. HS significantly increased surface area and length density of myocardial capillaries by 59%, 65% and 86%, and length density by 57%, 77% and 57%, respectively. Myocyte nuclear volume was significantly decreased in HS-treated rats. There was a decrease (although insignificant) in SBP and DBP with HA ingestion compared with controls. These changes suggest that the observed beneficial effect of HS on high BP in SHRs could be mediated through a reduction in the diffusion distance between capillaries and myocytes, as well as new vessel formation. It is proposed that these effects might be beneficial in restoring myocyte normal nutritional status compromised by the hypertrophic state of hypertension.

Hibiscus sabdariffa L., roselle calyx, from ethnobotany to pharmacology

Using MEDLINE and SCOPUS databases, a review of the literature from the pioneering study of 1991 until 2010 was performed on the effects on biological models of Hibiscus sabdariffa L. roselle calyx, its extracts mainly in polar solvents, or pure components found in extracts, as well as their possible relationship to these effects. Three relevant effects on lipid metabolism, antihypertensive activity, and apoptosis were observed. Our chronological review of the studies mentioned in the literature provides another opportunity to see how humans compile scientific knowledge of a chemical structure-physiological activity relationship starting from an ethnobotanical-ethnopharmagognosy contribution. The chemical components that are the main active principles in the physiological activities of Hibiscus sabdariffa L. calyx are anthocyanins and polyphenols (protocatechuic acid and quercetin). Advances have also been made in the elucidation of action mechanisms. Additionally, it has become clear that the lack of standardization in terms of chemical components of the material arising from Hibiscus sabdariffa L. used in testing on biological models imposes limits on the possibility of carrying out comparative analyses between studies. Fortunately, more recent studies are overcoming this obstacle by reporting component concentrations of assumed active principles; however, complete analysis of the extract, if this is to be considered as a therapeutic agent, is not commonly reported in the aforesaid studies. If one of the eventual scenarios for Hibiscus sabdariffa L. calyx is as a therapeutic agent in communities with economic limitations, then studies of a pharmacological nature should guarantee the effectiveness, safety, and tolerability of this material, which is widely accepted to be associated with chemical complexity, thus making this knowledge necessary.

Pharmacological characterization of the diuretic effect of Hibiscus sabdariffa Linn (Malvaceae) extract

ETHNOPHARMACOLOGICAL RELEVANCE

Hibiscus sabdariffa L. (Malvaceae) populary known in Mexico as "Jamaica", "flor de Jamaica", has widely used in Mexican Traditional Medicine as antihypertensive and diuretic, although the latter activity has been reported the present work show evidence about the diuretic, natriuretic and potassium-sparing effects.

AIM OF THE STUDY

To evaluate the diuretic activity of Hibiscus sabdariffa aqueous extract on in vivo and in situ models.

MATERIALS AND METHODS

The Hibiscus sabdariffa aqueous extract was administrated in increasing doses and evaluated the diuresis produced and disposal of electrolytes. Moreover, in isolated kidney was determined the renal filtration rate with plant extract, furosemide and amiloride.

RESULTS

The yield of Hibiscus sabdariffa aqueous extraction was 28.3% and the chemical standardization from 1 g of extract was: 56.5 mg delphinidin-3-O-sambubioside, 20.8 mg/g cyanidin-3-O-sambubioside, 3.2 mg/g quercetin, 2.1 mg/g rutin and 2.7 mg/g chlorogenic acid. The diuretic and natriuretic effect of Hibiscus sabdariffa aqueous extract showed a dose-dependent behavior. The pharmacological constants of natriuretic effect was ED50=86 mg/kg and Emax=0.9 mEq/100 g/5 h. In the model of kidney in situ was observed that renal filtration increased 48% with the aqueous extract of Hibiscus sabdariffa and an additive effect when was perfuse with furosemide.

CONCLUSION

The compound presents in Hibiscus sabdariffa as quercetin had effect on the vascular endothelium causing oxide nitric release, increasing renal vasorelaxation by increasing kidney filtration. Therefore, the diuretic effect of Hibiscus sabdariffa may be mediated by nitric oxide release.

Effect of Hibiscus sabdariffa and its Anthocyanins on Some Reproductive Aspects in Rats

An aqueous extract of Hibiscus sabdariffa L. is a common beverage in many parts of the world. Reports on its effect on reproduction are conflicting, with anecdotal evidence that the plant is an aphrodisiac, while others report that it is estrogenic, and adversely affects spermatogenesis in rats. We have studied the effect of different concentrations of aqueous extracts of H. sabdariffa calyces (10%, 15% and 20%) used as drinking water for 10 consecutive weeks, and its anthocyanins (50, 100, 200 mg/kg for 5 days, orally) on the weight and histology of the testis, and on some biochemical constituents in testicular homogenates, in addition to the plasma concentrations of testosterone, luteinizing hormone and estradiol. The possible presence of an estrogenic effect of the extract and anthocyanins on the uteri of immature female rats was also tested. Neither the H. sabdariffa extract nor the anthocyanins significantly altered either testicular weight and histology, or uterus weight. Plasma concentrations of the three hormones studied, the testicular concentrations of protein, reduced glutathione and total cholesterol, and superoxide dismutase activity were all insignificantly affected by either the extract or the anthocyanins, except for a slight, but statistically significant, decrease in testicular protein concentration caused by the 15% aqueous extract when compared with controls. These results suggest that H. sabdariffa exerts no adverse effect on the male reproductive system. Consumption of H. sabdariffa aqueous extract inhibited the growth of the rats compared with the controls.