Hibiscus sabdariffa L. extracts reduce serum uric acid levels in oxonate-induced rats

Effects of different levels of dried onion powder on nutrient digestibility, biochemical parameters, and nitrogen balance in Wistar albino rats with induced hyperuricemia

Introduction: Onions (Allium cepa L.) are excellent sources of bioactive compounds and phytochemicals such as allicin, quercetin, fisetin, and other sulfurous compounds. Therefore, our study aimed to investigate the effects of dried onion powder on growth performance, nitrogen balance, and biochemical parameters in Wistar albino rats with induced hyperuricemia. Methods: A total of 24 rats were randomly divided into four groups, with six in each group: HU (positive control) and HOT1, HOT2, and HOT3 groups, which received a diet containing onion powder at concentrations of 11.13, 14.84, and 18.61 g/100 g, respectively. Hyperuricemia was induced in rats by administering a new formulation intraperitoneally (250 mg/kg potassium oxonate) and orally (40 mg/kg potassium bromate) daily for 14 days. After confirmation of hyperuricemia induction, rats were fed with onion-treated diets with various concentrations of quercetin for 21 days. Results: Significant decreases (p ≤ 0.05) in serum uric acid, alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, total bilirubin, total cholesterol, and low-density lipoprotein were observed. An increasing trend (p ≤ 0.05) in the levels of hemoglobin (Hb), white blood cell (WBC), red blood cell (RBC), and platelet count was observed. An improvement in the levels of serum high-density lipoprotein, triglycerides, blood urea nitrogen, serum creatinine, serum total protein and neutrophils, lymphocytes, and monocytes was observed. A positive progress (p ≤ 0.05) was observed in growth performance and nutrient digestibility. Conclusion: In conclusion, a significantly lower uric acid level was observed in rats fed with HOT2 diet. Based on the ratio of the surface area (human/rat), the best recommended dose of onion for the incidence and prevention of hyperuricemia is 189.95 g, corresponding to the dose of 204 mg/day of quercetin in humans.

Evaluation of anti-hyperuricemic effects of Alocasia longiloba Miq. (Keladi Candik) extracts in potassium oxonate induced rat model

Hyperuricemia has become a significant public-health concern in recent years, and the available treatments have been reported to have an adverse side effect on patients. Alocasia longiloba has been used traditionally in Malaysia for treating gout, inflammation, and wounds. However, the plant has not been investigated for its effects on hyperuricemia. This study investigated the anti-hyperuricemic and anti-inflammatory effects of A. longiloba extracts in hyperuricemic rats induced by potassium oxonate (250 mg/kg body weight). Rats were given A. longiloba extracts or a standard drug for two-week, and blood and tissue samples were collected for analysis. Results show that A. longiloba extracts significantly reduced serum uric acid levels in hyperuricemic rats and inhibited xanthine oxidase (XOD) activity in the liver and kidney, which could be the mechanism underlying the urate-lowering effects. The extracts also significantly (p < 0.05) reduced the levels of proinflammatory cytokines (IL-18 and IL-1β) in serum samples and had hepatoprotective and nephroprotective effects in hyperuricemic rats. The study supports the use of A. longiloba as a complementary therapy for treating hyperuricemia.

Beneficial effects of phenolic compounds: native phenolic compounds vs metabolites and catabolites

In the human body, the positive effects of phenolic compounds are increasingly observed through their presence in tissues and organs in their native form or in the form of metabolites or catabolites formed during digestion, microbial metabolism, and host biotransformation. The full extent of these effects is still unclear. The aim of this paper is to review the current knowledge of beneficial effects of native phenolic compounds or their metabolites and catabolites focusing on their role in the health of the digestive system, including disorders of the gastrointestinal and urinary tracts and liver. Studies are mostly connecting beneficial effects in the gastrointestinal and urinary tract to the whole food rich in phenolics, or to the amount of phenolic compounds/antioxidants in food. Indeed, the bioactivity of parent phenolic compounds should not be ignored due to their presence in the digestive tract, and the impact on the gut microbiota. However, the influence of their metabolites and catabolites might be more important for the liver and urinary tract. Distinguishing between the effects of parent phenolics vs metabolites and catabolites at the site of action are important for novel areas of food industry, nutrition and medicine.

Action mechanisms of two key xanthine oxidase inhibitors in tea polyphenols and their combined effect with allopurinol

BACKGROUND

Tea polyphenols have been reported to have the effect of lowering uric acid. However, there are few studies on the inhibitory effects and molecular mechanisms of specific catechins on the urate-metabolizing enzyme xanthine oxidase (XO). In this research, multiple spectroscopic methods and computer simulations were used to determine the inhibitory ability and mechanisms of epigallocatechin gallate (EGCG) and gallocatechin gallate (GCG) on XO.

RESULTS

Herein, EGCG and GCG reversibly inhibited XO activity in a mixed manner, with IC₅₀ values of 40.50 ± 0.32 and 33.60 ± 0.53 μmol L^-1 , and also decreased the superoxide anion radical (O₂ ^- ) of the catalytic system by reducing the XO molecule and inhibiting the formation of uric acid. The combination of EGCG or GCG with allopurinol showed synergistic inhibition on XO. The binding of EGCG or GCG to XO with moderate affinity formed a stable complex by hydrogen bonds and van der Waals forces. The presence of EGCG and GCG made the structure of XO more stable and compact. The two inhibitors bound to the vicinity of flavin adenine dinucleotide (FAD) in XO, hindering the entry of substrate; thus the activity of XO was suppressed.

CONCLUSION

Both EGCG and GCG are excellent natural XO inhibitors, and inhibited the activity of XO by occupying the channel of the substrate to enter the active center and interfering with the dual substrate reaction catalyzed by XO. These findings provide a scientific basis for the application of catechins in dietary supplements and medicines with lowering uric acid effects. © 2022 Society of Chemical Industry.

Use of Hibiscus sabdariffa Calyxes in Meat Products

In the search for new ingredients that counteract some of the problems associated with the consumption of meat and meat products like high contents of saturated fat, salt, cholesterol, the absence of dietary fiber, and the presence of synthetic additives, Hibiscus sabdariffa calyxes have shown good colorant, antimicrobial, and antioxidant properties. This research paper studies the use of H. sabdariffa roselle calyxes directly or by means of extracts in meat and meat products. Although its application is incipient, the results are promising. The vibrant red color of the calyxes makes calyxes suitable for their use in meat products even though the concentration must be optimized since the acid taste can detract from the overall acceptance. The antimicrobial properties contribute to safer meat products, and antioxidant effects, helping to extend the shelf life of meat products and reducing oxidative processes. Nonetheless, achieving the desired effects is still challenging since several factors can affect these functional properties.

Physiological Effects and Human Health Benefits of Hibiscus sabdariffa: A Review of Clinical Trials

Hibiscus sabdariffa Linn. Malvaceae (HS) is characterized by its edible calyxes. The HS calyxes are widely used for cosmetic, food, and medicinal applications. According to ethnobotanical evidence, decoction, infusion, or maceration extracts from HS calyxes have been used in folk medicine to treat many ailments. Moreover, several in vitro and in vivo studies have demonstrated the pharmacological properties and potential human health benefits of HS consumption. On the other hand, the evaluation of the physiological effects and health benefits of HS in clinical studies is most challenging. Therefore, this narrative review summarizes and discusses the physiological effects and health benefits of HS calyxes reported in clinical trials. Preparations obtained from HS calyxes (extracts, infusions, decoction, teas, beverages, capsules, and pills) are used as non-pharmacological therapies to prevent/control diverse chronic non-communicable diseases. The most-reported HS health benefits are its antihypertensive, antidyslipidemic, hypoglycemic, body fat mass reduction, nephroprotective, antianemic, antioxidant, anti-inflammatory, and anti-xerostomic activities; these effects are associated with the phytochemicals found in HS. Moreover, no adverse effects were reported during the clinical trials. However, clinical studies exhibited some limitations; thus, further studies are required to validate the clinical efficacy of HS in large-scale studies with higher doses and a good experimental design

The Efficacy and Mechanism of Chinese Herbal Medicines in Lowering Serum Uric Acid Levels: A Systematic Review

Background. Chinese herbal medicines are widely used to lower serum uric acid levels. However, no systemic review summarizes and evaluates their efficacies and the underlying mechanisms of action. Objectives. To evaluate the clinical and experimental evidences for the effectiveness and the potential mechanism of Chinese herbal medicines in lowering serum uric acid levels. Methods. Four electronic databases PubMed, Wed of Science, the Cochrane Library and Embase were used to search for Chinese herbal medicines for their effects in lowering serum uric acid levels, dated from 1 January 2009 to 19 August 2020. For clinical trials, randomized controlled trials (RCTs) were included; and for experimental studies, original articles were included. The methodological quality of RCTs was assessed according to the Cochrane criteria. For clinical trials, a meta-analysis of continuous variables was used to obtain pooled effects. For experimental studies, lists were used to summarize and integrate the mechanisms involved. Results. A total of 10 clinical trials and 184 experimental studies were included. Current data showed that Chinese herbal medicines have promising clinical efficacies in patients with elevated serum uric acid levels (SMD: −1.65, 95% CI: −3.09 to −0.22; p = 0.024). There was no significant difference in serum uric acid levels between Chinese herbal medicine treatments and Western medicine treatments (SMD: −0.13, 95% CI: −0.99 to 0.74; p = 0.772). Experimental studies revealed that the mechanistic signaling pathways involved in the serum uric acid lowering effects include uric acid synthesis, uric acid transport, inflammation, renal fibrosis and oxidative stress. Conclusions. The clinical studies indicate that Chinese herbal medicines lower serum uric acid levels. Further studies with sophisticated research design can further demonstrate the efficacy and safety of these Chinese herbal medicines in lowering serum uric acid levels and reveal a comprehensive picture of the underlying mechanisms of action.

Targets and mechanisms of dietary anthocyanins to combat hyperglycemia and hyperuricemia: a comprehensive review

Hyperglycemia and hyperuricemia are both metabolic disorders related to excessive amount of metabolites in blood, which are considered as high risk factors for the development of many chronic diseases. Enzymes, cells, tissues and organs, which are relevant to metabolism and excretion of glucose and UA, are usually regarded to be the targets in treatment of hyperglycemia and hyperuricemia. Several drugs have been commonly applied to combat hyperglycemia and hyperuricemia through various targets but with unignorable side effects. Anthocyanins have become promising alternatives against hyperglycemia and hyperuricemia because of their bio-activities with little side effects. Structurally different anthocyanins from berry fruits, cherries and purple sweet potato lead to the diverse functional activity and property. This review is aimed to illustrate the specific targets that are available for anthocyanins from berry fruits, cherries and purple sweet potato in hyperglycemia and hyperuricemia management, as well as discuss the structure-activity relationship, and the underlying mechanisms associated with intracellular signaling pathway, anti-oxidative stress and anti-inflammation. In addition, the relationship of hyperglycemia and hyperuricemia, and the possibly regulative role of anthocyanins against them, along with the effects of anthocyanins in clinical trial are mentioned.

Effect and Mechanism of ShiZhiFang on Uric Acid Metabolism in Hyperuricemic Rats

Objective

To explore the effect and mechanism of ShiZhiFang on uric acid metabolism.

Methods

40 rats were divided into normal group, model group, ShiZhiFang group, and benzbromarone group. The hyperuricemic rat model was induced by yeast gavage at 15 g/kg and potassium oxonate intraperitoneal injection at 600 mg/kg for two weeks. During the next two weeks, ShiZhiFang group rats were given ShiZhiFang by gavage, and benzbromarone group rats were given benzbromarone by gavage. The serum uric acid, creatinine, blood urea nitrogen, XOD activity, urinary uric acid, urinary β₂-MG, and histopathological changes were observed in the rats of each group after treatment.

Results

The hyperuricemic model was established successfully and did not show the increase of serum creatinine and blood urea nitrogen. Compared with the model group, the serum uric acid, serum XOD activity, and urinary β₂-MG were significantly decreased (p < 0.05), and 24 h urinary uric acid excretion was significantly decreased (p < 0.01) in ShiZhiFang group, whereas the two treatment groups were of no statistical significant in above indicators (p > 0.05); renal histopathology showed that the lesions in two treatment groups were reduced compared to the model groups. The gene and protein expression of uric acid anion transporters rOAT1 and rOAT3 in the kidney was significantly higher than that in model group (p < 0.01).

Conclusion

The model is suitable for the study of primary hyperuricemia. The mechanisms of ShiZhiFang on uric acid metabolism in hyperuricemic rats may be involved in reducing the activity of serum XOD and promoting the transcription and expression of rOAT1 and rOAT3 in the kidney.

A review on phytochemistry and therapeutic uses of Hibiscus sabdariffa L

Hibiscus sabdariffa L. (roselle) belonging to the Malvaceae family is widely grown in many countries. This plant is often used in the traditional medicine being rich in phytochemicals like polyphenols especially anthocyanins, polysaccharides and organic acids thus having enormous prospective in modern therapeutic uses. The study aimed to review and document all the available evidence and information about the calyces of Hibiscus sabdariffa (roselle) with the special focus on their nutritional composition, bioactive constituents and therapeutic uses. The electronic database was searched up to 2017, using keywords Hibiscus sabdariffa, chemical constituents of roselle, therapeutic uses of roselle. Journals, books and conference proceedings were also searched. The review provides valuable information about the nutraceutical component of Hibiscus sabdariffa L. and their utilization for curing various degenerative diseases like hypertension, hyperlipidemia, cancer and other inflammatory diseases of liver and kidney. Their toxicological effects have also been discussed from a safety point of view. Most studies supported and provided the scientific basis for the statement that Hibiscus sabdariffa and their active constituents play an important role in the prevention of chronic and degenerative diseases that are associated with oxidative stress. Our study suggests, that good research is needed, to establish a potential strategy that can balance the pharmacological and toxic effects of roselle and standardized fingerprint of Hibiscus sabdariffa is required internationally for quality control.

Anti-gout Potential of Malaysian Medicinal Plants

Gout is a type of arthritis that causes painful inflammation in one or more joints. In gout, elevation of uric acid in the blood triggers the formation of crystals, causing joint pain. Malaysia is a mega-biodiversity country that is rich in medicinal plants species. Therefore, its flora might offer promising therapies for gout. This article aims to systematically review the anti-gout potential of Malaysian medicinal plants. Articles on gout published from 2000 to 2017 were identified using PubMed, Scopus, ScienceDirect, and Google Scholar with the following keyword search terms: “gout,” “medicinal plants,” “Malaysia,” “epidemiology,” “in vitro,” and “in vivo.” In this study, 85 plants were identified as possessing anti-gout activity. These plants had higher percentages of xanthine oxidase inhibitory activity (>85%); specifically, the Momordica charantia, Chrysanthemum indicum, Cinnamomum cassia, Kaempferia galanga, Artemisia vulgaris, and Morinda elliptica had the highest values, due to their diverse natural bioactive compounds, which include flavonoids, phenolics, tannin, coumarins, luteolin, and apigenin. This review summarizes the anti-gout potential of Malaysian medicinal plants but the mechanisms, active compounds, pharmacokinetics, bioavailability, and safety of the plants still remain to be elucidated.

Isolation and Characterization of Key Genes that Promote Flavonoid Accumulation in Purple-leaf Tea (Camellia sinensis L.)

There were several high concentrations of flavonoid components in tea leaves that present health benefits. A novel purple-leaf tea variety, 'Mooma1', was obtained from the natural hybrid population of Longjing 43 variety. The buds and young leaves of 'Mooma1' were displayed in bright red. HPLC and LC-MS analysis showed that anthocyanins and O-Glycosylated flavonols were remarkably accumulated in the leaves of 'Mooma1', while the total amount of catechins in purple-leaf leaves was slightly decreased compared with the control. A R2R3-MYB transcription factor (CsMYB6A) and a novel UGT gene (CsUGT72AM1), that were highly expressed in purple leaf were isolated and identified by transcriptome sequencing. The over-expression of transgenic tobacco confirmed that CsMYB6A can activate the expression of flavonoid-related structural genes, especially CHS and 3GT, controlling the accumulation of anthocyanins in the leaf of transgenic tobacco. Enzymatic assays in vitro confirmed that CsUGT72AM1 has catalytic activity as a flavonol 3-O-glucosyltransferase, and displayed broad substrate specificity. The results were useful for further elucidating the molecular mechanisms of the flavonoid metabolic fluxes in the tea plant.

Management of hyperuricemia through dietary polyphenols as a natural medicament: A comprehensive review

Hyperuricemia, a condition due to high serum uric acid level and is notorious to health. It is considered to be a potent risk factor for gout and dramatically associated in the development of many chronic diseases such as malignant tumor, cardiovascular disorders and renal failure. Modern innovative medicinal and therapeutic interventions are underlying these days to combat hyperuricemia. Previously reported studies revealed the significant impact of dietary polyphenols (e.g. anthocyanins, phenolic acids, flavonoids etc.) against hyperurecemia disorder. Dietary plant polyphenols, unlike anti- hyperuricemic agents, are not reported to have any side effects in curing hyperuricemia. The current comprehensive review figure outs the use of dietary polyphenols as a natural remedy for the management of hyperuricemia. The sources, affiliated pathways, mode of actions and factors affecting their efficiency to prevent hyperuricemia are deeply discussed in this article. Additionally, limitations and suggestions regarding previously reported studies are also highlighted.

Antihyperuricemic effects of thiadiazolopyrimidin-5-one analogues in oxonate treated rats

Hyperuricemia is a risk factor for not only gout, but also to a variety of disorders that affect the vital organ systems of the human body. The xanthine oxidase (XO) is the key enzyme in the production of uric acid and its inhibition can inhibit hyperuricemia. Although, XO inhibitor allopurinol is widely prescribed antigout agent but its use is not without any side effects. Previously, we described the synthesis of four novel thiadiazolopyrimidin-5-one analogues as effective XO inhibitors and molecular docking studies also confirmed this. When these analogues were tested in potassium oxonate treated rats, their serum uric acid and creatinine levels were dropped significantly from 4.85±0.03 mg/dl to 1.21±0.01 mg/dl and 0.92±0.02 mg/dl to 0.40±0.02 mg/dl respectively. Among the pyrimidine analogues tested, 6a was most potent. Histological examinations of both liver and kidney tissues exhibited severe necrosis in oxonate treated rats and pyrimidine analogues could significantly attenuate this with a correlative inhibitory profile of hepatic XO from the same rats. Our results demonstrate antihyperuricemic effect of novel thiadiazolopyrimidin-5-one analogues in oxonate treated rats, which can be further explored not only as antigout therapeutics but also in other systems where hyperuricemia is the driving cause of the disease.

Variations in chemical fingerprints and major flavonoid contents from the leaves of thirty-one accessions of Hibiscus sabdariffa L

The leaves of Hibiscus sabdariffa L. have been used as traditional folk medicines for treating high blood pressure and fever. There are many accessions of H. sabdariffa L. throughout the world. To assess the chemical variations of 31 different accessions of H. sabdariffa L., fingerprinting analysis and quantitation of major flavonoids were performed by high‐performance liquid chromatography (HPLC). The HPLC method was validated for linearity, sensitivity, precision, repeatability and accuracy. A quadrupole‐time‐of‐flight mass spectrometry (Q‐TOF‐MS) was applied for the characterization of major compounds. A total of 9 compounds were identified, including 6 flavonoids and 3 phenolic acids. In the fingerprint analysis, similarity analysis (SA) and principal component analysis (PCA) were used to differentiate the 31 accessions of H. sabdariffa L. Based on the results of PCA and SA, the samples No. 15 and 19 appeared much different from the main group. The total content of five flavonoids varied greatly among different accessions, ranging from 3.35 to 23.30 mg/g. Rutin was found to be the dominant compound and the content of rutin could contribute to chemical variations among different accessions. This study was helpful to understand the chemical variations between different accessions of H. sabdariffa L., which could be used for quality control. © 2015 The Authors Biomedical Chromatography Published by John Wiley & Sons Ltd.

Modification of the liver fatty acids by Hibiscus sabdariffa Linnaeus (Malvaceae) infusion, its possible effect on vascular reactivity in a metabolic syndrome model

We investigated the effects of Hibiscus sabdariffa Linnaeus (HSL)-fed infusion on the fatty acid (FA) profile in liver of metabolic syndrome (MS) rats and its possible effect on vascular reactivity. Body mass, intra-abdominal fat, triglycerides, insulin, blood pressure, saturated, monounsaturated FA, NEFAs, Δ(9)-, Δ(6)-desaturases and vasoconstriction were increased, while vasorelaxation, polyunsaturated FA, endothelial nitric oxide and [Formula: see text]/[Formula: see text] ratio decreased in MS versus Control, but HSL infusion modified it and increased Δ(5)-desaturase. The results suggest that the alteration in FA liver metabolism in the MS contributes to impaired vascular reactivity, but treatment with of HSL infusion can improve this condition.

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.