Hibiscus sabdariffa polyphenolic extract inhibits hyperglycemia, hyperlipidemia, and glycation-oxidative stress while improving insulin resistance

Efficacy of Hibiscus sabdariffa L. extract on metabolic parameters in participants with abdominal obesity and mild metabolic syndrome in Bangkok, Thailand: A double-blind, randomized, placebo-controlled trial

BACKGROUND

Hibiscus sabdariffa L. (HS) has been investigated as an alternative treatment for metabolic syndrome (MetS), as it affects all MetS components with low side effects simultaneously; however, clinical evidence regarding its efficacy compared with placebo is inconsistent. This study assessed how the aqueous calyx extract of HS influences insulin resistance and MetS parameters and examined the safety effects on liver, kidney, and hematological indexes in participants with abdominal obesity and mild MetS symptoms.

METHODS

In this double-blind, randomized, placebo-controlled trial, 108 participants with MetS were randomly assigned to take 1000-mg HS (45.04 mg/day in total polyphenols) or placebo daily for 12 weeks. Insulin resistance (HOMA-IR), glycemic markers, body mass index (BMI), waist circumference (WC), lipid profiles, and blood pressure were assessed at baseline, 6 weeks, and 12 weeks. Additionally, liver and kidney function indicators along with hematological parameters were evaluated.

RESULTS

Compared with placebo, HS did not significantly affect HOMA-IR, glycemic markers, BMI, WC, lipid profile, or blood pressure. Although HS did not significantly alter the lipid profile overall, serum low-density lipoprotein (LDL) levels decreased significantly at 12 weeks compared with baseline (- 7.98 mg/dL, [95 % CI, - 14.80, - 1.15]). Additionally, HS did not cause significant liver or kidney function or hematological changes compared with placebo.

CONCLUSION

Taking 1000-mg HS daily for 12 weeks seems to be safe. Placebo and HS groups showed good clinical results, and the extract was not associated with improved metabolic parameters in individuals with abdominal obesity and mild MetS symptoms, with the exception of lower serum LDL.

Efficacy and safety of Hibiscus sabdariffa in cardiometabolic health: An overview of reviews and updated dose-response meta-analysis

BACKGROUND

Conventional treatments for cardiometabolic diseases face limitations related to cost, efficacy, and side effects. Hibiscus sabdariffa (HS) is a common food product and a potential alternative. However, previous studies have shown inconsistent results and lacked assessments of result certainty, intervention safety, and subgroup analysis credibility. This study evaluated the efficacy and safety of HS on blood pressure (BP), lipid profiles, glycemic control, anthropometric parameters, inflammatory markers, oxidative stress indicators, and liver enzymes.

METHODS

To conduct this umbrella review, a systematic search of eligible meta-analyses was performed up to May 2024. The random-effects model was used to synthesize results from individual trials. Quality, certainty, and credibility of evidence were evaluated using the Cochrane Risk of Bias tool, AMSTAR-II, GRADE, and ICEMAN frameworks.

RESULTS

Data from 26 randomized controlled trials involving 1797 participants revealed that HS dose-dependently reduced systolic and diastolic BP compared to placebo and other teas. Although no significant differences were found between HS and antihypertensive drugs, HS showed moderate credibility for therapeutic BP reduction (> 10 mmHg), especially in individuals over 50 years, in trials lasting over four weeks, and in those with a low risk of bias. HS also reduced total cholesterol, LDL-C, fasting blood glucose, and increased HDL-C. A minor, clinically insignificant increase in aspartate aminotransferase was observed without elevating adverse event risks.

CONCLUSIONS

HS showed BP-lowering effects comparable to antihypertensive drugs and beneficial impacts on lipid and glycemic profiles. Although HS is generally considered safe, long-term and therapeutic dosing safety requires careful monitoring.

Research advances in the therapy of metabolic syndrome

Metabolic syndrome refers to the pathological state of metabolic disorder of protein, fat, carbohydrate, and other substances in the human body. It is a syndrome composed of a group of complex metabolic disorders, whose pathogenesis includes multiple genetic and acquired entities falling under the category of insulin resistance and chronic low-grade inflammationand. It is a risk factor for increased prevalence and mortality from diabetes and cardiovascular disease. Cardiovascular diseases are the predominant cause of morbidity and mortality globally, thus it is imperative to investigate the impact of metabolic syndrome on alleviating this substantial disease burden. Despite the increasing number of scientists dedicating themselves to researching metabolic syndrome in recent decades, numerous aspects of this condition remain incompletely understood, leaving many questions unanswered. In this review, we present an epidemiological analysis of MetS, explore both traditional and novel pathogenesis, examine the pathophysiological repercussions of metabolic syndrome, summarize research advances, and elucidate the mechanisms underlying corresponding treatment approaches.

Medicinal Plant Extracts against Cardiometabolic Risk Factors Associated with Obesity: Molecular Mechanisms and Therapeutic Targets

Obesity has increasingly become a worldwide epidemic, as demonstrated by epidemiological and clinical studies. Obesity may lead to the development of a broad spectrum of cardiovascular diseases (CVDs), such as coronary heart disease, hypertension, heart failure, cerebrovascular disease, atrial fibrillation, ventricular arrhythmias, and sudden cardiac death. In addition to hypertension, there are other cardiometabolic risk factors (CRFs) such as visceral adiposity, dyslipidemia, insulin resistance, diabetes, elevated levels of fibrinogen and C-reactive protein, and others, all of which increase the risk of CVD events. The mechanisms involved between obesity and CVD mainly include insulin resistance, oxidative stress, inflammation, and adipokine dysregulation, which cause maladaptive structural and functional alterations of the heart, particularly left-ventricular remodeling and diastolic dysfunction. Natural products of plants provide a diversity of nutrients and different bioactive compounds, including phenolics, flavonoids, terpenoids, carotenoids, anthocyanins, vitamins, minerals, fibers, and others, which possess a wide range of biological activities including antihypertensive, antilipidemic, antidiabetic, and other activities, thus conferring cardiometabolic benefits. In this review, we discuss the main therapeutic interventions using extracts from herbs and plants in preclinical and clinical trials with protective properties targeting CRFs. Molecular mechanisms and therapeutic targets of herb and plant extracts for the prevention and treatment of CRFs are also reviewed.

A Holistic In Silico and In Vivo Approach to Exploring the Antidiabetic, Antioxidant, and Hepatoprotective Properties of Rose of Sharon

Diabetes mellitus (DM) is a significant global health burden that necessitates the exploration of effective and accessible therapeutic options. Phytotherapy has played a vital role in healthcare, with plant extracts being integral to traditional medicinal practices. The therapeutic potential of Hibiscus syriacus (Rose of Sharon), a plant with a rich ethnobotanical history, in the management of DM and its associated complications was investigated. In this study, the therapeutic potential of Hibiscus syriacus L. extract (HSE) against DM in streptozotocin (STZ)-induced diabetic rats was assessed, focusing on its effects on glucose regulation, antioxidative defense, and liver protection. The administration of the HSE extract substantially reduced hyperglycemia and increased insulin production, with concurrent improvements in body weight and hydration. The enhanced activity of antioxidant enzymes, such as superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px), suggests reduced oxidative stress, which is further supported by molecular docking results with the 3GTV superoxide dismutase enzyme, showing a binding energy of -6.3 kcal/mol. A decrease in MDA levels also indicates a reduction in oxidative stress. Notably, HSE treatment led to decreased aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels and improved lipid profiles, indicating its hepatoprotective and lipid-modifying benefits. These findings support the inclusion of HSE as an adjunctive therapy in DM management strategies. This study promotes the consideration of Hibiscus syriacus L. therapeutic properties in global health contexts.

Roselle Calyx (Hibiscus sabdariffa L.) Ethyl Acetate Fraction Lowering Malondialdehyde and TNF-α and Reducing Hypercoagulability in Diabetic Model

INTRODUCTION

Traditionally and empirically, Hibiscus sabdariffa L. has been used in treating diabetes mellitus due to its antioxidant activity. This study aimed to investigate the effect of administering the ethyl acetate fraction of hibiscus calyxes (EAFHCs) on malondialdehyde (MDA) levels, tumor necrosis factor-α (TNF-α) levels, bleeding time, and platelet count in male white rats induced with streptozotocin-induced diabetes.

METHOD

Thirty-six Wistar Kyoto rats were induced with intraperitoneal streptozotocin at 55 mg/kg BW and stabilized for 5 days to obtain diabetic conditions. Diabetic animals were divided into four groups; the diabetic group was given vehicle, the glibenclamide group was given 0.45 mg/kg BW of glibenclamide, and two groups were administered the EAFHCs at doses of 100 mg/kg BW and 200 mg/kg BW for 5 days. Subsequently, the MDA, TNF-α, bleeding time and platelet count levels were examined on days 1, 3, and 5, respectively. All data were analyzed using two-way ANOVA followed by the Duncan Multiple Range Test (DMRT).

RESULTS

EAFHC significantly reduced MDA and TNF-α levels (p < 0.05). Additionally, this fraction appeared to shorten bleeding time and decrease platelet count in diabetic rats. Administration of the EAFHC for 5 days effectively lowered MDA and TNF-α levels significantly, decreased platelet counts and prolonged coagulation (p < 0.05) in diabetic rats.

CONCLUSION

This study demonstrates that EAFHC effectively reduces MDA and TNF-α levels and reduces the risk of hypercoagulability in diabetic model.

Novel Insight into the Cellular and Molecular Signalling Pathways on Cancer Preventing Effects of Hibiscus sabdariffa: A Review

A category of diseases known as cancer includes abnormal cell development and the ability to infiltrate or spread to other regions of the body, making them a major cause of mortality worldwide. Chemotherapy, radiation, the use of cytotoxic medicines, and surgery are the mainstays of cancer treatment today. Plants or products produced from them hold promise as a source of anti-cancer medications that have fewer adverse effects. Due to the presence of numerous phytochemicals that have been isolated from various parts of the Hibiscus sabdariffa (HS) plant, including anthocyanin, flavonoids, saponins, tannins, polyphenols, organic acids, caffeic acids, citric acids, protocatechuic acid, and others, extracts of this plant have been reported to have anti-cancer effects. These compounds have been shown to reduce cancer cell proliferation, induce apoptosis, and cause cell cycle arrest. They also increase the expression levels of the cell cycle inhibitors (p53, p21, and p27) and the pro-apoptotic proteins (BAD, Bax, caspase 3, caspase 7, caspase 8, and caspase 9). This review highlights various intracellular signalling pathways involved in cancer preventive potential of HS.

Antioxidant Capacity of Polar and Non-Polar Extracts of Four African Green Leafy Vegetables and Correlation with Polyphenol and Carotenoid Contents

In sub-Saharan Africa, chronic malnutrition is often associated with intestinal inflammation and oxidative stress. African green leafy vegetables (GLVs), commonly consumed by these populations and rich in bioactive compounds, may improve the antioxidant status. The aim of this study was to measure the antioxidant capacity using complementary assays (DPPH, FRAP, ABTS, ORAC and NO scavenging) in polar and non-polar leaf extracts of four African GLVs, cassava (Manihot esculenta), roselle (Hibiscus sabdariffa), jute mallow (Corchorus olitorius), and amaranth (Amaranthus spp.), with spinach (Spinacia oleracea) chosen as a reference. Their antioxidant capacity was correlated with their total polyphenol (TPC), flavonoid (TFC), condensed tannin, lutein, and β-carotene contents. Identification of phenolic compounds by UHPLC-DAD-MS/MS revealed the presence of three main classes of compound: flavonols, flavones, and hydroxycinnamic acids. Cassava and roselle leaves presented significantly higher TPC and TFC than amaranth, jute mallow, and spinach. They also exhibited the highest antioxidant capacity, even higher than that of spinach, which is known for its important antioxidant effect. The antioxidant capacity was 2 to 18 times higher in polar than non-polar extracts, and was more strongly correlated with TPC and TFC (R > 0.8) than with β-carotene and lutein contents. These findings provide new data especially for cassava and roselle leaves, for which studies are scarce, suggesting an appreciable antioxidant capacity compared with other leafy vegetables.

Promising Therapeutic Treatments for Cardiac Fibrosis: Herbal Plants and Their Extracts

Cardiac fibrosis is closely associated with multiple heart diseases, which are a prominent health issue in the global world. Neurohormones and cytokines play indispensable roles in cardiac fibrosis. Many signaling pathways participate in cardiac fibrosis as well. Cardiac fibrosis is due to impaired degradation of collagen and impaired fibroblast activation, and collagen accumulation results in increasing heart stiffness and inharmonious activity, leading to structure alterations and finally cardiac function decline. Herbal plants have been applied in traditional medicines for thousands of years. Because of their naturality, they have attracted much attention for use in resisting cardiac fibrosis in recent years. This review sheds light on several extracts from herbal plants, which are promising therapeutics for reversing cardiac fibrosis.

Impact of Processing and Physicochemical Parameter on Hibiscus sabdariffa Calyxes Biomolecules and Antioxidant Activity: From Powder Production to Reconstitution

Hibiscus sabdariffa is a tropical plant with red calyxes whose anthocyanins, phenols, and antioxidant activity make it attractive to consumers both from a nutritional and medicinal standpoint. Its seasonality, perishability, and anthocyanin instability, led to the setup of stabilization methods comprising drying and powdering. However, its properties can often be altered during these stabilization processes. Treatments such as dehumidified-air-drying, infrared drying, and oven-drying, and their combination showed better quality preservation. Moreover, powder production enables superior biomolecule extractability which can be linked to a higher bioaccessibility. However, the required temperatures for powder production increase the bioactive molecules degradation leading to their antioxidant activity loss. To overcome this issue, ambient or cryogenic grinding could be an excellent method to improve the biomolecule bioavailability and accessibility if the processing steps are well mastered. To be sure to benefit from the final nutritional quality of the powder, such as the antioxidant activity of biomolecules, powders have to offer excellent reconstitutability which is linked to powder physicochemical properties and the reconstitution media. Typically, the finest powder granulometry and using an agitated low-temperature reconstitution media allow for improving anthocyanin extractability and stability. In this review, the relevant physicochemical and processing parameters influencing plant powder features from processing transformation to reconstitution will be presented with a focus on bioactive molecules and antioxidant activity preservation.

Effect of Cornus mas L. fruit extract on blood pressure, anthropometric and body composition indices in patients with non-alcoholic fatty liver disease: A double-blind randomized controlled trial

BACKGROUND & AIMS

Obesity is linked to the pathogenesis of non-alcoholic fatty liver disease (NAFLD). Patients with NAFLD are at increased risk for hypertension. Some investigations have hypothesized that Cornus mas L. fruit can improve obesity and hypertension. We investigated the effect of C. mas L. fruit extract on blood pressure, anthropometric and body composition indices in patients with NAFLD.

METHODS

This 12-week double-blind randomized controlled trial was conducted on fifty patients with NAFLD. Patients received 20 cc/d C. mas L. fruit extract or placebo. We measured diastolic blood pressure (DBP), systolic blood pressure (SBP), weight, waist circumference (WC), hip circumference (HC), waist-to-hip ratio (WHR), body fat mass (BFM), body fat percent (BFP) and fat free mass (FFM) before and after intervention.

RESULTS

Treatment group compared to control group showed a significant reduction in DBP (-8.62 ± 11.86 mmHg vs. 0.53 ± 8.53 mmHg; P_crude = 0.003; P_adjucted = 0.03) and SBP (-8.63 ± 14.37 mmHg vs. 0.0 ± 12.67 mmHg; P_crude = 0.02; P_adjucted = 0.02). We found no difference between groups in weight, WC, HC, WHR, BFM, BFP and FFM (P > 0.05). After adjusting for confounding factors, a significant reduction was observed in treatment group compared to control group in BFM (-0.2 ± 3.9 kg vs. 0.7 ± 2.4 kg; P = 0.01) and BFP (-0.2 ± 4.9% vs. 0.8 ± 2.8%; P = 0.02).

CONCLUSIONS

C. mas L. fruit extract statistically reduced blood pressure and body fat. However, it had no effect on other anthropometric and body composition indices. Studies with larger sample sizes and higher dosages of extract are needed.

TRIAL REGISTRATION

Registered on 30/9/2018 at Iranian Registry of Clinical Trials IRCT20180419039359N1 (https://www.irct.ir/trial/30707).

Insulin: A connection between pancreatic β cells and the hypothalamus

Insulin is a hormone secreted by pancreatic β cells. The concentration of glucose in circulation is proportional to the secretion of insulin by these cells. In target cells, insulin binds to its receptors and activates phosphatidylinositol-3-kinase/protein kinase B, inducing different mechanisms depending on the cell type. In the liver it activates the synthesis of glycogen, in adipose tissue and muscle it allows the capture of glucose, and in the hypothalamus, it regulates thermogenesis and appetite. Defects in insulin function [insulin resistance (IR)] are related to the development of neurodegenerative diseases in obese people. Furthermore, in obesity and diabetes, its role as an anorexigenic hormone in the hypothalamus is diminished during IR. Therefore, hyperphagia prevails, which aggravates hyper-glycemia and IR further, becoming a vicious circle in which the patient cannot regulate their need to eat. Uncontrolled calorie intake induces an increase in reactive oxygen species, overcoming cellular antioxidant defenses (oxidative stress). Reactive oxygen species activate stress-sensitive kinases, such as c-Jun N-terminal kinase and p38 mitogen-activated protein kinase, that induce phos-phorylation in serine residues in the insulin receptor, which blocks the insulin signaling pathway, continuing the mechanism of IR. The brain and pancreas are organs mainly affected by oxidative stress. The use of drugs that regulate food intake and improve glucose metabolism is the conventional therapy to improve the quality of life of these patients. Currently, the use of antioxidants that regulate oxidative stress has given good results because they reduce oxidative stress and inflammatory processes, and they also have fewer side effects than synthetic drugs.

Angiopoietin-Like Protein Responses to Pecan-Enriched Diets Versus a Nut-Excluded Diet

Daily pecan consumption improves fasting and postprandial triglycerides, but its effect on angiopoietin-like proteins (ANGPTLs) is unknown. The objective of this study was to investigate the impact of daily pecan consumption for 8 weeks on fasting and postprandial ANGPTL3, -8, and -4. This was an 8-week, randomized, controlled trial with three treatments: two pecan groups and a nut-free control group (n = 16). The ADD group (n = 15) consumed pecans (68 g) as part of a free-living diet, and the SUB group (n = 16) substituted the pecans (68 g) for isocaloric foods from their habitual diet. Fifty-six participants were randomized but nine subjects did not begin or finish the 8-week intervention and/or testing visits. At pre- and post-intervention, a high saturated fat meal was consumed with 3.5 h postprandial blood draws to determine changes in ANGPTL3, -8, and -4. There was a significant suppression in postprandial ANGPTL3 from pre- to post-intervention within ADD and SUB (P = .004 and P = .002, respectively) but not control (ns). There were no other changes within or between groups for fasting and postprandial outcomes. Daily pecan consumption improved postprandial ANGPTL3, which may mediate improvements in lipid metabolism.

Hibiscus sabdariffa in Diabetes Prevention and Treatment—Does It Work? An Evidence-Based Review

Diabetes is currently a global health problem that is already reported as an epidemic. This metabolic disease, characterized by a disturbance in the carbohydrate, protein, and lipid metabolism, is often accompanied by disorders of several organs. Its treatment is expensive and often difficult to control. Therefore, it seems necessary to search for new drugs and solutions to facilitate therapy and reduce treatment costs. Herbal medicines are becoming more and more popular. Hibiscus sabdariffa (roselle) is a plant that grows wild in a tropical climate. It has been used in folk medicine for thousands of years. Thanks to the numerous active compounds, including polyphenols, polysaccharides, organic acids, or pectins, it is reported to exhibit hypoglycemic, antioxidant, hypotensive, and anti-lipidemic activities and numerous indirect effects that are related to them. The aim of this review was to update the knowledge about the therapeutic effects of roselle in diabetes and its comorbidities based on in vitro, animal, and human studies. After a careful analysis of the scientific literature, it can be stated that roselle is a promising product that can be used either on its own or as an addition to the conventional treatment regimens to prevent or treat diabetes and its accompanying diseases.

Medicinal plants with anti-colorectal cancer bioactive compounds: Potential game-changers in colorectal cancer management

Development and identification of molecular compounds capable of killing or inhibiting transformed cells promoting carcinogenesis without inducing toxic effects to the normal cells are of utmost significance. A systematic review was conducted in screening for important literature was extensively performed by searching the Web of Science, Ovid, BMC Springer, Elsevier, Embase, and MEDLINE databases for optimum selectivity. Google Scholar was also used to supplement information. Pharmacotherapeutic biomolecules active against colon cancer carcinogenesis in Musa acuminata and Musa balbisiana (bananas), Punica granatum L (pomegranate), Glycine max (Soybean), Brassica oleracea L var. italica Plenck (Broccoli), and Hibiscus rosa-sinesis and Hibiscus sabdariffa (hibiscus) were evaluated. Signaling pathways like phosphatidylinositol 3-kinase (PI3K), mitogen-activated protein kinase (MAPK), protein kinase B (AKT), and nuclear factor-kappa B (NFκB) correlate the mediation of COX-2 expression. Increased levels of COX-2 are correlated with the occurrence and progression of colon cancer. Natural antioxidants in herbal plants including polyphenols and carotenoids inhibit the oxidation of lipids, proteins, and nucleic acids and thereby preventing the initiation of oxidizing chain reactions. These bioactive compounds should be considered an important dietary supplement.

Emerging Approach for the Application of Hibiscus sabdariffa Extract Ointment in the Superficial Burn Care

Wound healing comprises organized events involving tissue repair and regeneration. The discovery of toll-like receptors (TLRs) sheds recent light on the mechanisms involved in initiating inflammatory responses throughout the healing cascades. Hibiscus sabdariffa (HS) components may exhibit a wound healing action, owing to their antioxidant and anti-inflammatory activities. This study was designed to investigate the early effects of HS loaded in an ointment base on wound healing, antioxidant, antimicrobial effects, burning intensity, and histopathological features on the rat burn model in comparison to the standard treatment, Iruxol® ointment. A burn injury model was used to evaluate the wound healing potency of the preparation. Rats were treated with ointments three times on the day of the induction of the burn. Findings revealed that the strong antioxidant properties of the HS-loaded ointment augmented the skin healing potential by stimulating biomarkers required for skin regeneration. HS repressed the burning-induced inflammation by the effective reduction in the levels of tumor necrosis factor α (TNF-α) and IL-6 through TLR4 protein inhibition. Topical HS downregulates transforming growth factor-beta (TGF-β) levels. HS extract possesses a potential bactericidal activity against highly resistant clinical isolates of Pseudomonas aeruginosa. Overall, this study proclaims that HS-loaded topical preparations could be a valuable product that serves as adjuvants to accelerate burn wound healing through inactivating the TLR4 pathway.

Terminalia catappa aqueous leaf extract reverses insulin resistance, improves glucose transport and activates PI3K/AKT signalling in high fat/streptozotocin-induced diabetic rats

Rising prevalence of type 2 diabetes mellitus (T2DM) in sub-Saharan Africa has necessitated surveys of antidiabetic medicinal plants. This study assessed the antidiabetic mechanism of Terminalia catappa aqueous leaf extract (TCA) in high fat/low dose streptozotocin-induced type 2 diabetic rats. T2DM was induced by a combination of high-fat diet and low dose STZ (30 mg/kg bw) and the animals were administered with TCA (400 and 800 mg/kg bw) orally daily for 28 days. Biochemical parameters and indices for diabetes including renal function tests and pancreatic histology were evaluated. Relative expression of hepatic insulin resistance, signalling and glucose transport genes were also assessed. Induction of T2DM resulted in significant (p < 0.05) weight loss, dysregulated glucose level and clearance, electrolyte imbalance and disrupted diabetic biochemical parameters. Diabetes onset also perturbed β-cell function and insulin resistance indices, damaged pancreas microanatomy, while disrupting the expression of insulin receptor substrate 1 (IRS-1), phosphatidylinositol 3-kinase (PI3K), protein kinase B (AKT) and glucose transporter isoform 4 (GLUT-4) mRNA. Oral treatment of diabetic animals with TCA significantly (p < 0.05) ameliorated alterations due to T2DM induction in a manner comparable with glibenclamide. These results suggest TCA exerts its antidiabetic action by reversing insulin resistance, improving glucose transport and activating PI3K/AKT signalling.

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

Bioactivity of Dietary Polyphenols: The Role in LDL-C Lowering

Cardiovascular diseases are the leading causes of the death around the world. An elevation of the low-density lipoprotein cholesterol (LDL-C) level is one of the most important risk factors for cardiovascular diseases. To achieve optimal plasma LDL-C levels, clinal therapies were investigated which targeted different metabolism pathways. However, some therapies also caused various adverse effects. Thus, there is a need for new treatment options and/or combination therapies to inhibit the LDL-C level. Dietary polyphenols have received much attention in the prevention of cardiovascular diseases due to their potential LDL-C lowering effects. However, the effectiveness and potential mechanisms of polyphenols in lowering LDL-C is not comprehensively summarized. This review focused on dietary polyphenols that could reduce LDL-C and their mechanisms of action. This review also discussed the limitations and suggestions regarding previous studies.

Systematic Review of Medicinal Plants Used for Treatment of Diabetes in Human Clinical Trials: An ASEAN Perspective

Traditionally, there are some medicinal plants believed to treat diabetes, as they have been proven in research studies to possess antidiabetic properties, such as improved insulin sensitivity and hypoglycemic activities, due to their high level of phenolic compounds, flavonoids, terpenoids, alkaloids, and glycosides. We conducted a systematic review to identify potential medicinal plants used during human clinical trials in the Association of Southeast Asian Nation (ASEAN) countries on prediabetic or type 2 diabetic individuals and to potentially identify any bioactive compounds involved in effectively treating symptoms of diabetes such as lowering of blood glucose. A total of 1209 reference titles were retrieved from four selected databases (Science Direct, Scopus, Springer Link, and PubMed) and only three met the inclusion criteria. Upon evaluation of the selected articles, four medicinal plants were identified: turmeric (Curcuma longa), garlic (Allium sativum L.), bitter melon (Momordica charantia), and Rosella flower (Hibiscus sabdariffa L.). Of these, only the bitter melon study did not show any significant change in the blood glucose of participants after intervention. This review demonstrates the limitations in published articles of human clinical trials for medicinal plants' intervention for diabetes. Upon further investigations on the four identified medicinal plants included in the animal studies, the findings showed positive effects in the management of diabetes, such as hyperglycemia. Hence, further testing and standardization of the methods in the studies can be suggested for human clinical trials for reliable data collections such as methods of extract preparation, duration of intervention, and conditions set for the study design.

Traditionally Used Plants in the Treatment of Diabetes Mellitus: Screening for Uptake Inhibition of Glucose and Fructose in the Caco2-Cell Model

The traditional use of plants and their preparations in the treatment of diseases as a first medication in the past centuries indicates the presence of active components for specific targets in the natural material. Many of the tested plants in this study have been traditionally used in the treatment of Diabetes mellitus type 2 and associated symptoms in different cultural areas. Additionally, hypoglycemic effects, such as a decrease in blood glucose concentration, have been demonstrated in vivo for these plants. In order to determine the mode of action, the plants were prepared as methanolic and aqueous extracts and tested for their effects on intestinal glucose and fructose absorption in Caco2 cells. The results of this screening showed significant and reproducible inhibition of glucose uptake between 40 and 80% by methanolic extracts made from the fruits of Aronia melanocarpa, Cornus officinalis, Crataegus pinnatifida, Lycium chinense, and Vaccinium myrtillus; the leaves of Brassica oleracea, Juglans regia, and Peumus boldus; and the roots of Adenophora triphylla. Furthermore, glucose uptake was inhibited between 50 and 70% by aqueous extracts made from the bark of Eucommia ulmoides and the fruit skin of Malus domestica. The methanolic extracts of Juglans regia and Peumus boldus inhibited the fructose transport between 30 and 40% in Caco2 cells as well. These findings can be considered as fundamental work for further research regarding the treatment of obesity-correlated diseases, such as Diabetes mellitus type 2.

Acute consumption of pecans decreases angiopoietin-like protein-3 in healthy males: a secondary analysis of randomized controlled trials

Angiopoietin-like proteins (ANGPTL)-3 and -4 regulate lipid metabolism, but the effect of tree nuts of varying fatty acid composition on post-meal responses is unknown. The purpose of the study was to conduct a secondary analysis of two studies on ANGPTL3 and -4 responses to meals containing different tree nuts. We hypothesized that the pecan-containing meal would mitigate postprandial rises in ANGPTL3 compared to the traditional meal without nuts in males, but not females. In addition, we hypothesized that there would be no other differences between any other treatments in ANGPTL3 or -4 responses. The two studies were double-blind, randomized crossover trials. Twenty-two adults (10=male, 12=female) completed study 1, which compared meals containing pecans vs. no nuts (control), and thirty adults (14=male, 16=female) completed study 2, which compared meals containing black walnuts, English walnuts (EW), or no nuts (control). Blood was collected at fasting, 30, 60, 120, and 180min postprandially. In study 1, ANGPTL3 was suppressed more in pecan vs. control in males (iAUC: -579.4±219.4 vs. -128.4±87.1pg/mL/3h, P<.05). In study 2, there was no difference in ANGPTL3 between black walnuts vs. EW, but ANGPTL3 was suppressed more in control vs. black walnuts in females only (iAUC: -196.4±138.4 vs. 102.1±90.1pg/mL/3h, P<.05). There were no differences in ANGPTL4 between treatments. In conclusion, adding pecans to a meal decreased ANGPTL3 in males, but not females. These data highlight the importance of investigating the impact of nutrients and sex on postprandial ANGPTL3 ad -4 responses to better understand their ability to reduce cardiovascular disease risk.

The Digestibility of Hibiscus sabdariffa L. Polyphenols Using an In Vitro Human Digestion Model and Evaluation of Their Antimicrobial Activity

Hibiscus sabdariffa L. (H.s.) is a polyphenolic-rich plant commonly consumed either as a beverage or spice. The aim of the present study was to evaluate the in vitro digestibility of H.s. polyphenols using an in vitro model of digestion which simulates the human stomach and small intestine. The bioaccessible polyphenols released in the digested samples were analyzed by liquid chromatography coupled to photodiode array and mass spectrometry detection. H.s. anthocyanins (cyanidin-3-O-sambubioside and delphinidin-3-O-sambubioside) content drastically dropped during the digestion process from 2.91 ± 0.03 µg g⁻¹ and 8.53 ± 0.08 µg g⁻¹ (w/w) CG (Cyanidin-glucoside) in the raw extract, respectively, to 0.12 ± 0.01 µg g⁻¹ 0.12 ± 0.01 µg g⁻¹ (w/w) CG at the end of duodenal digestion. Total polyphenols also have shown a decrease from 1192.65 ± 30.37 µg g⁻¹ (w/w) in the raw extract to 282.24 ± 7.21 µg g⁻¹ (w/w) by the end of gastric digestion, in contrast to their increase by the end of duodenal digestion 372.91 ± 3.97 µg g⁻¹ (w/w). On the other hand, the decrease in certain compounds (e.g., caffeoylquinicandcoumaroylquinic acids) was observed during gastric digestion resulting in an increase of quinic acid in the duodenal aliquots, thus suggesting that this compound was derived from the degradation of the more complex hydroxycinnamic acids. H.s. extract also exhibited a bacteriostatic effect against Staphylococcus aureus ATCC 6538 (MIC of 2.5 mg mL⁻¹) and a bactericidal effect against a food isolate of Listeria monocytogenes (MBC of 2.5 mg mL⁻¹). The undigested polyphenols of H.s. in the upper gastrointestinal tract enters the colon, where they are metabolized by the gut microbiota. The present study results showed that resistance of H.s. polyphenols during gastrointestinal digestion might affect their uptake, resulting in a decrease in their digestibility.

A review of the effectiveness of hibiscus for treatment of metabolic syndrome

ETHNOPHARMACOLOGICAL RELEVANCE

Hibiscus species (Family: Malvaceae) have long been used in traditional medicine to treat a variety of maladies such as abscesses, bilious conditions, cancer, cough, fatigue, gastrointestinal discomfort, fever, veisalgia, cardiovascular disorders, neurosis, scurvy, and urinary tract disorders. Its antioxidants have the capacity to destroy free radicals that damage cells and increase risk of inflammatory conditions such as metabolic syndrome, cancer, and cardiovascular disease.

AIM OF THE STUDY

This review synthesizes findings from animal studies and clinical trials to assess effectiveness of hibiscus for treating biomarkers of metabolic syndrome including hyperglycemia, hypertriglyceridemia, low high-density lipoprotein, obesity, and hypertension.

MATERIALS AND METHODS

We searched for 12 edible species of hibiscus in the Google Scholar database. Each scientific name of these species, their common names and their edible plant parts were searched in conjunction with fourteen key words associated with metabolic syndrome. A total of 68 articles met all inclusion criteria for this review, including 18 that tested human subjects, 48 that tested other animals, one that tested humans and other animals, and one that did not specify.

RESULTS

Hibiscus often improved blood glucose, total cholesterol, high-density lipoprotein cholesterol, triglycerides, blood pressure, weight, lipid absorption and oxidation of fatty acids within vital organs around the abdominal cavity. Higher doses led to greater benefits in some cases, especially for body mass of animals, but lower doses were often equally effective. Hibiscus was often equally or more effective than pharmaceuticals in improving some biomarkers of metabolic syndrome, especially blood glucose and insulin sensitivity.

CONCLUSION

Hibiscus shows great promise for improving biomarkers of metabolic syndrome, but there are limitations that need to be addressed by future work, including increasing the number and size of human clinical trials, expanding human trials to include people from a greater diversity of ethnicities, taking into account the health and physical activity of human participants, investigating the influence of growing conditions and extraction/preparation techniques on nutrients in hibiscus, comparing the efficacy of several plant parts and plant products of hibiscus to a reference control group within the same experiment, incorporating rigorous statistical analysis of treatments and investigating the influence of dosage.

Phenolic Compounds from Leaves and Flowers of Hibiscus roseus: Potential Skin Cosmetic Applications of an Under-Investigated Species

The use of plant extracts in skin-care cosmetics is a modern trend due to their richness in polyphenols that act as anti-aging molecules. Hibiscus roseus is a perennial species naturalized in Italy, with beautiful soft pink flowers; its phenolic composition and biological activities have not been studied yet. The aim of this study was to characterize and quantify the phenolics and to evaluate the antioxidant, sun protection factor (SPF), and anti-collagenase activities of the ethanolic extracts of H. roseus leaves (HL) and flowers (HF). p-Coumaric, chlorogenic, and trans-ferulic acids derivatives as well as quercetin and kaempferol flavonoids were the main phenolic compounds detected. Catechin, epicatechin, kaempferol-3-O-rutinoside, kaempferol-3-O-glucoside, kaempferol-7-O-glucoside, tiliroside, oenin, and peonidin-3-O-glucoside were detected only in HF, while phloridzin was exclusive from HL, which also showed greater amounts of hydroxycinnamic acid derivatives. HF was richer in flavonoids and total phenolics, also exhibiting greater antioxidant capacity. The SPF and anti-collagenase activity of both extracts were similar and comparable to those of synthetic standards. The overall results demonstrate that H. roseus extracts are promising sources of bioactive phenolic compounds that could be potentially applied as anti-aging agents in skin-care cosmetics.

Mechanisms of Action of Nutritionally Rich Hibiscus sabdariffa's Therapeutic Uses in Major Common Chronic Diseases: A Literature Review

Hibiscus sabdariffa, this beverage has been used for millennia as both a delicious cultural beverage and an ancient medicinal therapy. In recent years, many studies have investigated the uses and mechanisms of action of Hibiscus sabdariffa to treat common chronic diseases. In this literature review, we place the spotlight on Hibiscus sabdariffa's medical effect on common chronic diseases, the flower commonly used to make hibiscus tea. The databases PubMed, MEDLINE, Clinical Key, and CINAHL were searched for studies related to Hibiscus sabdariffa's compounds, antioxidative and anti-inflammatory features, mechanism of action on common chronic diseases including hypertension, hyperlipidemia, obesity, diabetes, and Alzheimer's disease. Hibiscus sabdariffa antihypertensive potentials originate from the vasodilator activity, diuretic efficacy, functionality as an ACE inhibitor, adipocyte differentiation inhibitor, heart rate reduction ability, and anti-inflammatory mechanistic. The antihyperlipidemic effect is dose-dependent and stems from the antioxidative effect and the activation of AMPK through phosphorylation and the inhibition of regulatory adipogenic transcription factors PPAR-γ, C/EBP-α, and SREBP-1c, which altogether results in lipid-lowering effect. As an antihyperglycemic, Hibiscus sabdariffa serves as anti-insulin resistance by inhibition of the phosphorylation of IRS-1 beside a similar effect to gliptins. Finally, Hibiscus sabdariffa was proven to protect against neuroinflammation in microglial cell culture exposed to LPS by decreasing IL-1, IL-6, TNF-α expression, and the protective effect against glucotoxicity, improve memory function by inhibiting the formation of hyperphosphorylated tau proteins in the mouse brain. Regular consumption of hibiscus tea or extract is beneficial for a reduction in chronic disease risk and diagnosis. Key teaching pointsHibiscus sabdariffa, or hibiscus, has been used for millennia as both a delicious cultural beverage and an ancient medicinal therapy. Recent studies have investigated the uses of Hibiscus sabdariffa to treat common chronic diseases.Its antihypertensive potential originates from the vasodilator activity, diuretic efficacy, functionality as an ACE inhibitor, adipocyte differentiation inhibitor, heart rate reduction ability, and anti-inflammatory mechanistics.The antihyperlipidemic effect is dose-dependent and stems from the antioxidative effect and the activation of AMPK through phosphorylation and also the inhibition of regulatory adipogenic transcription factors PPAR-γ, C/EBP-α and SREBP-1c which all together results in lipid-lowering effect.As an antihyperglycemic, Hibiscus sabdariffa serves as anti-insulin resistance by inhibition of the phosphorylation of IRS-1 beside the similar effect to gliptins.Hibiscus sabdariffa was proven to protect against neuroinflammation in microglial cell culture exposed to LPS by decreasing IL-1, IL-6, TNF-α expression, and the protective effect against glucotoxicity, improve memory function by inhibiting the formation of hyperphosphorylated tau proteins in the mouse brain.

Hibiscus cannabinus L. (kenaf) studies: Nutritional composition, phytochemistry, pharmacology, and potential applications

The electronic database was searched up to July 2020, using keywords, kenaf and roselle, chemical constituents of kenaf and roselle, therapeutic uses of kenaf and roselle. Journals, books and conference proceedings were also searched. Investigations of pharmacological activities of kenaf revealed that this edible plant exhibits a broad range of therapeutic potential including antioxidant, antimicrobial, antityrosinase, anticancer, antihyperlipidemia, antiulcer, anti-inflammatory, and hepatoprotective activities. Kenaf also showed versatile utility as a functional ingredient in food, folk medicine, and animal nutritions, as well as in nanotechnology processes. The exploitation of underexploited kenaf by-products can be a significant part of waste management from an economic and environmental point of view. In addition, kenaf showed comparable nutritional, phytochemical, and pharmacological properties with Hibiscus sabdariffa (Roselle). This review has important implications for further investigations and applications of kenaf in food and pharmaceuticals industry.

Eurocristatine, a plant alkaloid from Eurotium cristatum, alleviates insulin resistance in db/db diabetic mice via activation of PI3K/AKT signaling pathway

Eurocristatine (ECT) is an alkaloid isolated from Eurotium cristatum, and it has been used in multiple applications. However, its use as a treatment for type 2 diabetes mellitus (T2DM) has not yet been reported. In this study, we investigated the anti-T2DM effect of ECT and explored its potential molecular mechanism. In vivo, after treatment with ECT (20, 40 mg/kg) for 6 weeks, fasting blood glucose (FBG) was remarkably reduced in db/db mice. Moreover, glucose tolerance, insulin sensitivity and hyperinsulinemia were ameliorated treatment with ECT. The values of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) also showed that ECT could alleviate liver toxicity caused by diabetes in db/db mice. In vitro, ECT (15 and 30 μM) alleviated insulin resistance by increasing glucose consumption, glucose uptake and glycogen content in high glucose-induced HepG2 cells. The Western blotting (WB) results showed that ECT could upregulate the expression of phosphatidylinositol 3-kinase (PI3K), increase the phosphorylation of insulin receptor substrate 1 (IRS1) and protein kinase B (AKT) in vivo and in vitro. Besides, ECT improved the glycogen content by inhibiting the expression of glycogen synthase kinase3β (GSK3β) and promoting that of glycogen synthase (GS). Furthermore, administration of the PI3K/AKT signaling pathway inhibitor LY294002 abolished the beneficial effects of ECT. These findings are the first to verify that ECT has the potential to improve glucose metabolism and alleviate insulin resistance by activating the PI3K/AKT signaling pathway in db/db mice.

Effect of sour tea supplementation on liver enzymes, lipid profile, blood pressure, and antioxidant status in patients with non-alcoholic fatty liver disease: A double-blind randomized controlled clinical trial

The aim of this study was to evaluate the efficacy of sour tea supplementation in patients with nonalcoholic fatty liver disease (NAFLD). Seventy NAFLD patients were enrolled in this randomized, double-blind, placebo-controlled clinical trial. Participants received sour tea in the form of a 450 mg capsule or a placebo capsule daily for 8 weeks. Anthropometric indices, liver enzymes, lipid profile, blood pressure, and antioxidant status were evaluated at the baseline and at the end of the study. Sixty-one participants completed the study. After 8 weeks, sour tea administration significantly decreased serum triglyceride (TG) (p = .03), alanine aminotransferase (ALT) (p = .01), and aspartate aminotransferase (AST) (p = .004) levels compared with the placebo. In addition, sour tea supplementation resulted in a significant reduction in systolic blood pressure (SBP) (p = .03) and diastolic blood pressure (DBP) (p = .04), and a significant increase in serum total antioxidant capacity (TAC) levels (p ˂ .001) compared with the placebo. However, no significant changes in anthropometric measures, total cholesterol (TC), low-density lipoprotein cholesterol (LDL-c), and high-density lipoprotein cholesterol (HDL-c) levels were observed after sour tea supplementation compared with the placebo (p > .05). Sour tea supplementation may be effective in improving serum TG, liver enzymes, and blood pressure in patients diagnosed with NAFLD. Further studies are needed to address the exact mechanism of action of these effects.

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.

Comparison Among Garlic, Berberine, Resveratrol, Hibiscus sabdariffa, Genus Zizyphus, Hesperidin, Red Beetroot, Catha edulis, Portulaca oleracea, and Mulberry Leaves in the Treatment of Hypertension and Type 2 DM: A Comprehensive Review

Diabetes mellitus (DM) and hypertension are 2 of the most prevalent diseases with poor impact on health status worldwide. In most cases, they coexist with other metabolic disorders as well as cardiac, micro- and macrovascular complications. Many plants are known for their hypotensive, cardioprotective, and/or antidiabetic activities. Their active ingredients either identified and isolated or still utilized as herbal preparations of certain plant parts. The use of medicinal plants comprises the main basis for most of the traditional medicine (TM) systems and procedures. As conventional medicines seem insufficient to control such progressive diseases, herbal agents from TM could be used as adjuvant with good impact on disease control and progression as well as other concomitant health conditions. The aim of this study is to compare the efficacy of 10 different herbal medicines of botanical origin or herbal preparations in the management of hypertension and its cardiovascular complications and type 2 DM along with various coexisting health disorders. These herbal medicines are garlic, berberine, resveratrol, Hibiscus sabdariffa, Zizyphus ( oxyphylla, mucronate, jujube, rugosa), hesperidin, red beetroot, Catha edulis, mulberry leaves, and Portulaca oleracea.

Metabolomics analysis and biological investigation of three Malvaceae plants

INTRODUCTION

Metabolomics is a fast growing technology that has effectively contributed to many plant-related sciences and drug discovery.

OBJECTIVE

To use the non-targeted metabolomics approach to investigate the chemical profiles of three Malvaceae plants, namely Hibiscus mutabilis L. (Changing rose), H. schizopetalus (Dyer) Hook.f. (Coral Hibiscus), and Malvaviscus arboreus Cav. (Sleeping Hibiscus), along with evaluating their antioxidant and anti-infective potential.

METHODOLOGY

Metabolic profiling was carried out using liquid chromatography coupled with high-resolution electrospray ionisation mass spectrometry (LC-HR-ESI-MS) for dereplication purposes. The chemical composition of the studied plants was further compared by principal component analysis (PCA). The antioxidant and anti-infective properties of their different extracts were correlated to their phytochemical profiles by orthogonal partial least square discriminant analysis (OPLS-DA).

RESULTS

A variety of structurally different metabolites, mostly phenolics, were characterized. Comparing the distribution pattern of these tentatively identified metabolites among the studied plant species/fractions revealed the chemical uniqueness of the dichloromethane fraction of M. arboreus. Some extracts and fractions of these plants demonstrated noteworthy antioxidant and antitrypanosomal potential; the latter was partly attributed to their anti-protease activities. The active principles of these plants were pinpointed before any laborious isolation steps, to avoid the redundant isolation of previously known compounds.

CONCLUSION

This study highlighted the use of the established procedure in exploring the metabolomes of these species, which could be helpful for chemotaxonomic and authentication purposes, and might expand the basis for their future phytochemical analysis. Coupling the observed biological potential with LC-MS data has also accelerated the tracing of their bioactive principles.

Polyphenols and AGEs/RAGE axis. Trends and challenges

The formation of advanced glycation end-products (AGEs) is a key pathophysiological event linked not only to the onset and progression of diabetic complications, but also to neurodegeneration, cardiovascular diseases, cancer, and others important human diseases. AGEs contributions to pathophysiology are mainly through the formation of cross-links and by engaging the receptor for advanced glycation end-products (RAGE). Polyphenols are secondary metabolites found largely in fruits, vegetables, cereals, and beverages, and during many years, important efforts have been made to elucidate their beneficial effects on human health, mainly ascribed to their antioxidant activities. In the present review, we highlighted the beneficial actions of polyphenols aimed to diminish the harmful consequences of advanced glycation, mainly by the inhibition of ROS formation during glycation, the inhibition of Schiff base, Amadori products, and subsequent dicarbonyls group formation, the activation of the glyoxalase system, as well as by blocking either AGEs-RAGE interaction or cell signaling.

Gymnemic Acid Ameliorates Hyperglycemia through PI3K/AKT- and AMPK-Mediated Signaling Pathways in Type 2 Diabetes Mellitus Rats

Gymnemic acid (GA) isolated from Gymnema sylvestre (Retz.) Schult. has been shown to have antihyperglycemic activity; however, the molecular mechanisms governing these effects are unclear. In this study, GA (40 and 80 mg kg^-1 day^-1) was evaluated by type 2 diabetes mellitus (T2DM) rats to explore its hypoglycemic activity and underlying mechanisms of action. The results indicated that GA decreased fasting blood glucose (FBG) concentrations by 26.7% and lowered insulin concentrations by 16.1% after oral administration of GA at a dose of 80 mg kg^-1 day^-1 for 6 weeks in T2DM rats. Our data showed that real-time polymerase chain reaction and western blot indicated that GA upregulated the level of phosphatidylinositol-3-kinase (PI3K) and glycogen synthesis (GS) and promoted the phosphorylation of protein kinase B (Akt) while downregulated the expression of glycogen synthesis kinase-3β (GSK-3β) in T2DM rats. In addition, key proteins involved in adenosine monophosphate (AMP)-activated protein kinase (AMPK)-mediated gluconeogenesis [such as phosphoenolpyruvate carboxy kinase (PEPCK) and glucose-6-phosphatase (G6Pase)] were downregulated in GA-treated T2DM rats. In summary, the hypoglycemic mechanisms of GA may be related to promoting insulin signal transduction and activating PI3K/Akt- and AMPK-mediated signaling pathways in T2DM rats.

Effect of sieved fractionation on the physical, flow and hydration properties of Boscia senegalensis Lam., Dichostachys glomerata Forssk. and Hibiscus sabdariffa L. powders

This study aimed at evaluating the effect of successive grinding and sieving processes on the physicochemical properties of powders obtained from Boscia senegalensis seeds, Dichostachys glomerata fruits and Hibiscus sabdariffa calyxes. Plant powders were fractionated into four granulometric classes and their properties were compared to those of unsieved powders. Mean particle size exerted a significant influence (p < 0.05) on the plant powders properties. The smaller the particle size of the powder fraction, the higher the protein, lipid and ash contents and the lower the carbohydrate and fiber contents. The decrease in particle size increased particle sphericity and elongation and enhanced flowability of B. senegalensis and D. glomerata powders, whereas an inverse tendency seemed to be observed for H. sabdariffa powders. Water absorption capacity, water solubility index and dispersibility were improved for finer particles for all plants. Sieve fractionation is a novel approach for improving physicochemical properties of plant powders.

Antidiabetic activity-guided isolation of gallic and protocatechuic acids from Hibiscus sabdariffa calyxes

We isolated and identified gallic and protocatechuic acids as the antidiabetic principles in Hibiscus sabdariffa using solvent extraction, column chromatographic fractionation, and nuclear magnetic resonance (NMR) spectroscopy. Ethylacetate fraction of the aqueous extract of H. sabdariffa inhibited α-amylase and α-glucosidase with IC₅₀ of 411.73 and 433.93 μg/ml, respectively. Furthermore, fractions I and II obtained from column chromatography inhibited α-amylase with IC₅₀ of 27.03 and 20.12 μg/ml, and α-glucosidase with IC₅₀ of 24.30 and 22.29 μg/ml, respectively. In addition, the principles reduced the serum glucose and lipid peroxide levels of diabetic rats and with an improvement in the rat lipid profiles and antioxidant defenses. Fractions I and II were identified as protocatechuic acid and gallic acid, respectively, using ¹ H and ¹³ C NMR. Protein-ligand docking showed that these compounds form multiple favorable interactions with the active-site residues of the two glycosidases. Overall, protocatechuic and gallic acids emerge as natural antidiabetic agents. PRACTICAL APPLICATIONS: Hibiscus sabdariffa (Zoborodo) is a refreshment drink for ceremonial gatherings in Nigeria. Also, its pharmacological use includes diabetes, hypertension, hyperlipidemia, metabolic syndrome, and hepatoprotection. The consumption of this food drink could improve diabetes, hypertension, dyslipidemia, metabolic syndrome, and liver disease. Furthermore, the inhibition of α-amylase and α-glucosidase could prevent diabetic complications associated with postprandial glucose. Developing the extract of H. sabdariffa calyx as food supplement could be used in managing diabetes and its associated complications such as dyslipidemia, hypertension, and metabolic syndrome.

Dietary polyphenols modulate starch digestion and glycaemic level: a review

Polyphenols, as one group of secondary metabolite, are widely distributed in plants and have been reported to show various bioactivities in recent year. Starch digestion not only is related with food industrial applications such as brewing but also plays an important role in postprandial blood glucose level, and therefore insulin resistance. Many studies have shown that dietary phenolic extracts and pure polyphenols can retard starch digestion in vitro, and the retarding effect depends on the phenolic composition and molecular structure. Besides, dietary polyphenols have also been reported to alleviate elevation of blood glucose level after meal, indicating the inhibition of starch digestion in vivo. This review aims to analyze how dietary polyphenols affect starch digestion both in vitro and in vivo. We can conclude that the retarded starch digestion in vitro by polyphenols results from inhibition of key digestive enzymes, including α-amylase and α-glucosidase, as well as from interactions between polyphenols and starch. The alleviation of postprandial hyperglycemia by polyphenols might be caused by both the inhibited starch digestion in vivo and the influenced glucose transport. Therefore, phenolic extracts or pure polyphenols may be alternatives for preventing and treating type II diabetes disease.

Nelumbo nucifera leaves extract attenuate the pathological progression of diabetic nephropathy in high-fat diet-fed and streptozotocin-induced diabetic rats

Diabetic nephropathy is not only a common and severe microvascular complication of diabetes mellitus but also the leading cause of renal failure. Lotus (Nelumbo nucifera) possesses antioxidative and anticancer properties. The present study aimed to investigate the antidiabetic and renoprotective effects of N. nucifera leaf extract (NLE) in a rat model of type 2 diabetic mellitus. Male Sprague–Dawley rats with type 2 diabetes induced by a high-fat diet (HFD)/streptozotocin (STZ) were treated with NLE at dosages of 0.5% and 1% (w/w) daily for 6 weeks. At the end of the experimental period, body weight, serum glucose levels, insulin levels, and kidney function were assessed. Furthermore, antioxidant enzyme and lipid peroxide levels were determined in the kidney, and histopathological examination was performed using hematoxylin and eosin staining, periodic acid Schiff staining, and Masson trichrome staining. To shed light on the molecular mechanism underlying the functioning of NLE, mouse glomerular mesangial cells (MES-13) treated with high glucose (HG, 25 mM glucose) were chosen as a model for an examination of the signal transduction pathway of NLE. The results revealed that NLE improved diabetic kidney injury by reducing blood glucose, serum creatinine, and blood urea nitrogen levels and enhanced antioxidant enzyme activities in kidney tissue. Treatment with NLE significantly reduced the malondialdehyde and 8-hydroxy-2-deoxyguanosine levels and increased serum insulin levels; expression of renal superoxide dismutase, catalase, and glutathione peroxidase activities; and glutathione content. Histological studies have also demonstrated that NLE treatment inhibited the dilation of Bowman’s capsule, which confirmed its renoprotective action in diabetes. In addition, treatment with NLE and its major component quercetin 3-glucuronide attenuated 25 mM HG-induced suppressed nuclear factor erythroid 2-related factor 2 and antioxidant enzyme expression in MES-13 cells. Collectively, these findings indicate that NLE may have antidiabetic and renoprotective effects against HFD/STZ-induced diabetes, at least in part, through antioxidative pathways.

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.

Biogenic Au@ZnO core-shell nanocomposites kill Staphylococcus aureus without provoking nuclear damage and cytotoxicity in mouse fibroblasts cells under hyperglycemic condition with enhanced wound healing proficiency

The aim of the present study is focused on the synthesis of Au@ZnO core-shell nanocomposites, where zinc oxide is overlaid on biogenic gold nanoparticles obtained from Hibiscus Sabdariffa plant extract. Optical property of nanocomposites is investigated using UV-visible spectroscopy and crystal structure has been determined using X-ray crystallography (XRD) technique. The presence of functional groups on the surface of Au@ZnO core-shell nanocomposites has been observed by Fourier transforms infrared (FTIR) spectroscopy. Electron microscopy studies revealed the morphology of the above core-shell nanocomposites. The synthesized nanocomposite material has shown antimicrobial and anti-biofilm activity against Staphylococcus aureus and Methicillin Resistant Staphylococcus haemolyticus (MRSH). The microbes are notorious cross contaminant and are known to cause infection in open wounds. The possible antimicrobial mechanism of as synthesized nanomaterials has been investigated against Staphylococcus aureus and obtained data suggests that the antimicrobial activity could be due to release of reactive oxygen species (ROS). Present study has revealed that surface varnishing of biosynthesized gold nanoparticles through zinc oxide has improved its antibacterial proficiency against Staphylococcus aureus, whereas reducing its toxic effect towards mouse fibroblast cells under normal and hyperglycaemic condition. Further studies have been performed in mice model to understand the wound healing efficiency of Au@ZnO nanocomposites. The results obtained suggest the possible and effective use of as synthesized core shell nanocomposites in wound healing.

Hibiscus sabdariffa (roselle) polyphenol-rich extract averts cardiac functional and structural abnormalities in type 1 diabetic rats

Diabetes mellitus is often associated with cardiac functional and structural alteration, an initial event leading to cardiovascular complications. Roselle (Hibiscus sabdariffa) has been widely proven as an antioxidant and recently has incited research interest for its potential in treating cardiovascular disease. Therefore, this study aimed to determine the cardioprotective effects of H. sabdariffa (roselle) polyphenol-rich extract (HPE) in type-1-induced diabetic rats. Twenty-four male Sprague-Dawley rats were randomized into 4 groups (n = 6/group): nondiabetic, diabetic alone (DM), diabetic supplemented with HPE (DM+HPE), and diabetic supplemented with metformin. Type-1 diabetes was induced with streptozotocin (55 mg/kg intraperitoneally). Rats were forced-fed with HPE (100 mg/kg) and metformin (150 mg/kg) daily for 8 weeks. Results showed that HPE supplementation improved hyperglycemia and dyslipidemia significantly (p < 0.05) in the DM+HPE compared with the DM group. HPE supplementation attenuated cardiac oxidative damage in the DM group, indicated by low malondialdehyde and advanced oxidation protein product. As for the antioxidant status, HPE significantly (p < 0.05) increased glutathione level, as well as catalase and superoxide dismutase 1 and 2 activities. These findings correlate with cardiac function, whereby left ventricle developed pressure in DM+HPE (79.13 ± 3.08 mm Hg) was higher significantly compared with DM (45.84 ± 1.65 mm Hg). Coronary flow of DM+HPE (17.43 ± 0.62 mL/min) was also greater compared with DM (13.02 ± 0.6 mL/min), showing that HPE supplementation improved cardiac contractility and relaxation rate significantly (p < 0.05). Histological analysis showed a marked decrease in cardiomyocyte hypertrophy and fibrosis in DM+HPE compared with the DM group. Ultrastructural changes and impairment of mitochondria induced by diabetes were minimized by HPE supplementation. Collectively, these findings suggest that HPE is a potential cardioprotective agent in a diabetic setting through its hypoglycemic, anti-hyperlipidemia, and antioxidant properties.

Microwave-assisted extraction for Hibiscus sabdariffa bioactive compounds

H. sabdariffa has demonstrated positive results against chronic diseases due to the presence of phytochemicals, mainly phenolic compounds. The extraction process of bioactive compounds increases the efficient collection of extracts with high bioactivity. Microwave-Assisted Extraction (MAE) constituted a "green technology" widely employed for plant matrix. In this work, the impact of temperature (50-150 °C), composition of extraction solvent (15-75% EtOH) and extraction time (5-20 min) on the extraction yield and individual compounds concentrations were evaluated. Furthermore, the characterization of 16 extracts obtained was performed by HPLC-ESI-TOF-MS. The results showed that 164 °C, 12.5 min, 45% ethanol was the best extraction condition, although glycoside flavonoids were degraded. Besides that, the optimal conditions for extraction yield were 164 °C, 60% ethanol and 22 min. Thus, temperature and solvent concentration have demonstrated to be potential factors in MAE for obtaining bioactive compounds from H. sabdariffa.