Polyphenol extracts from Hibiscus sabdariffa Linnaeus attenuate nephropathy in experimental type 1 diabetes

Utilizing Natural Materials in Electronic Devices: Inching Toward "Herbal Electronics"

Sustainable development is the primary key to address global energy challenges. Though the scientific community is engaged in developing efficient ways to not only maximize energy production from natural resources like sun, wind, water, etc. but also to make all the electronic gadgets power efficient, despite all this, the materials used in most of the electronic devices are largely produced using various materials processing techniques and semiconductors, polymers, dielectrics, etc. which again increases the burden on energy and in turn affects the environment. While addressing these challenges, it is very important to explore the possibility to directly, or with minimum processing, utilize the potential of natural resources in the development of electronic devices. Recent articles are focused on the development of herbal electronic devices that essentially implement natural resources, like plants, leaves, etc., either in their raw or extracted form in the device assembly. This review encompasses the recent research developments around herbal electronic devices. Furthermore, herbal electronics has been discussed for several functional applications including electrochromism, energy storage, memresistor, LED, solar cell, water purification, pressure sensor, etc. Moreover, advantages, disadvantages, and challenges encountered in the realization of "herbal electronics" have been discussed at length.

Mango (Mangifera indica L.) seed kernel extract suppresses hyperglycemia by modulating pancreatic β cell apoptosis and dysfunction and hepatic glucose metabolism in diabetic rats

This study investigated the anti-hyperglycemic action of mango seed kernel extract (MKE) and various mechanisms involved in its actions to improve pancreatic β cells and hepatic carbohydrate metabolism in diabetic rats. An intraperitoneal injection of 60 mg/kg of streptozotocin (STZ) followed by 30 consecutive days of treatment with MKE (250, 500, and 1000 mg/kg body weight) was used to establish a study group of diabetic rats. Using liquid chromatography-electrospray ionization-quadrupole time-of-flight mass spectrometry (LC-ESI-QTOF-MS/MS) for identification, 26 chemical compounds were found in MKE and the high-performance liquid chromatography (HPLC) analysis of the MKE also revealed the existence of mangiferin, gallic acid, and quercetin. The results confirmed that in each diabetes-affected rat, MKE mitigated the heightened levels of fasting blood glucose, diabetic symptoms, glucose intolerance, total cholesterol (TC), and low-density lipoprotein-cholesterol (LDL-C). As demonstrated by a remarkable increment in serum and pancreatic insulin, the diabetic pancreatic β cell function was potentiated by treating with MKE. The effect of MKE on diabetic pancreatic apoptosis clearly reduced the terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL)-positive cells, which was related to diminished levels of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and Bax and an increase in Bcl-xL protein expression. Furthermore, diabetes-induced liver damage was clearly ameliorated along with a notable reduction in serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels and abnormal liver histology. By enhancing anti-oxidant superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) activities, MKE alleviated diabetes-induced pancreatic and liver oxidative damage, as demonstrated by diminished levels of malondialdehyde. In minimizing the expression levels of glucose 6-phosphatase and phosphoenolpyruvate carboxykinase-1 proteins in the diabetic liver, MKE also enhanced glycogen content and hexokinase activity. Collectively, these findings indicate that by suppressing oxidative and inflammatory processes, MKE exerts a potent anti-hyperglycemic activity in diabetic rats which serve to protect pancreatic β cell apoptosis, enhance their function, and improve hepatic glucose metabolism.

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.

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.

Dietary Parsley Seed Mitigates Methomyl-Induced Impaired Growth Performance, Hemato-Immune Suppression, Oxidative Stress, Hepato-Renal Damage, and Pseudomonas aeruginosa Susceptibility in Oreochromis niloticus

The present experiment investigated the potential protective role of parsley (Petroselinum crispum) seed meal (PSM) in alleviating methomyl (MET)-adverse impacts on growth, whole-body composition, hematological indicators, hepatorenal function, immune response, oxidative status, and disease resistance to Pseudomonas aeruginosa. For this purpose, 225 healthy Nile tilapia (Oreochromis niloticus) were allotted into five groups (45 fish/group in triplicate). One group was reared in clean water and fed a non-supplemented basal diet, while the other groups were exposed to 20.39 μg L^-1 MET and fed a non-fortified basal diet or basal diets supplemented with 0.5, 1.0, or 2.0% of PSM for 60 days. The obtained data revealed significantly lower weight gain, feed intake, and specific growth rate, but higher feed conversion ratio and decreases in crude protein, lipid, and ash contents in the MET-exposed fish. Anemia, leukopenia, lymphocytopenia, and esonipenia were also obvious. Furthermore, MET-exposed fish had significantly higher serum levels of hepatic enzymes and renal damage products. Nevertheless, there was a significant depletion of enzymatic and non-enzymatic antioxidants and increased malondialdehyde, myeloperoxidase, and tumor necrosis factor-α levels in MET-exposed fish. The MET exposure significantly depressed lysozyme activity, nitric oxide, complement3, acetylcholinesterase activity, total proteins, globulin, and albumin levels in O. niloticus serum. Furthermore, pathological alterations in the liver and kidney were noted. The relative percentage of survival rate in MET-exposed fish was dramatically reduced on day 14 post-challenge with P. aeruginosa. The inclusion of PSM, on the other hand, greatly alleviated most of the MET-related negative effects. Taken together, the dietary intervention with PSM has a promising role in alleviating MET-deleterious impacts, rendering parsley seeds a viable aqua feed additive for O. niloticus.

Dietary Polyphenols and Their Role in Oxidative Stress-Induced Human Diseases: Insights Into Protective Effects, Antioxidant Potentials and Mechanism(s) of Action

Dietary polyphenols including phenolic acids, flavonoids, catechins, tannins, lignans, stilbenes, and anthocyanidins are widely found in grains, cereals, pulses, vegetables, spices, fruits, chocolates, and beverages like fruit juices, tea, coffee and wine. In recent years, dietary polyphenols have gained significant interest among researchers due to their potential chemopreventive/protective functions in the maintenance of human health and diseases. It is believed that dietary polyphenols/flavonoids exert powerful antioxidant action for protection against reactive oxygen species (ROS)/cellular oxidative stress (OS) towards the prevention of OS-related pathological conditions or diseases. Pre-clinical and clinical evidence strongly suggest that long term consumption of diets rich in polyphenols offer protection against the development of various chronic diseases such as neurodegenerative diseases, cardiovascular diseases (CVDs), cancer, diabetes, inflammatory disorders and infectious illness. Increased intake of foods containing polyphenols (for example, quercetin, epigallocatechin-3-gallate, resveratrol, cyanidin etc.) has been claimed to reduce the extent of a majority of chronic oxidative cellular damage, DNA damage, tissue inflammations, viral/bacterial infections, and neurodegenerative diseases. It has been suggested that the antioxidant activity of dietary polyphenols plays a pivotal role in the prevention of OS-induced human diseases. In this narrative review, the biological/pharmacological significance of dietary polyphenols in the prevention of and/or protection against OS-induced major human diseases such as cancers, neurodegenerative diseases, CVDs, diabetes mellitus, cancer, inflammatory disorders and infectious diseases have been delineated. This review specifically focuses a current understanding on the dietary sources of polyphenols and their protective effects including mechanisms of action against various major human diseases.

Using polyphenols as a relevant therapy to diabetes and its complications, a review

Diabetes is currently a worldwide health concern. Hyperglycemia, hypertension, obesity, and oxidative stress are the major risk factors that inevitably lead to all the complications from diabetes. These complications severely impact the quality of life of patients, and they can be managed, reduced, or even reverted by several polyphenols, plant extracts and foods rich in these compounds. The goal of this review is to approach diabetes not as a single condition but rather an interconnected combination of risk factors and complications. This work shows that polyphenols have multi target action and effects and they have been systematically proven to be relevant in the reduction of each risk factor and improvement of associated complication.

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.

Modulation of Renal Function in a Metabolic Syndrome Rat Model by Antioxidants in Hibiscus sabdariffa L

Metabolic syndrome (MS) is the association of three or more pathologies among which obesity, hypertension, insulin resistance, dyslipidemia, and diabetes are included. It causes oxidative stress (OS) and renal dysfunction. Hibiscus sabdariffa L. (HSL) is a source of natural antioxidants that may control the renal damage caused by the MS. The objective of this work was to evaluate the effect of a 2% HSL infusion on renal function in a MS rat model induced by the administration of 30% sucrose in drinking water. 24 male Wistar rats were divided into 3 groups: Control rats, MS rats and MS + HSL rats. MS rats had increased body weight, systolic blood pressure, triglycerides, insulin, HOMA index, and leptin (p ≤ 0.04). Renal function was impaired by an increase in perfusion pressure in the isolated and perfused kidney, albuminuria (p ≤ 0.03), and by a decrease in clearance of creatinine (p ≤ 0.04). The activity of some antioxidant enzymes including the superoxide dismutase isoforms, peroxidases, glutathione peroxidase, glutathione-S-transferase was decreased (p ≤ 0.05). Lipoperoxidation and carbonylation were increased (p ≤ 0.001). The nitrates/nitrites ratio, total antioxidant capacity, glutathione levels and vitamin C were decreased (p ≤ 0.03). The treatment with 2% HSL reversed these alterations. The results suggest that the treatment with 2% HSL infusion protects renal function through its natural antioxidants which favor an improved renal vascular response. The infusion contributes to the increase in the glomerular filtration rate, by promoting an increase in the enzymatic and non-enzymatic antioxidant systems leading to a decrease in OS and reestablishing the normal renal function.

Flavonoids as natural phenolic compounds and their role in therapeutics: an overview

Background

Natural plants and plant-derived formulations have been used by mankind from the ancient period of time. For the past few years, many investigations elaborated the therapeutic potential of various secondary chemicals present in the plants. Literature revealed that the various secondary metabolites, viz. phenolics and flavonoids, are responsible for a variety of therapeutic action in humans.

Main body

In the present review, an attempt has been made to compile the exploration of natural phenolic compounds with major emphasis on flavonoids and their therapeutic potential too. Interestingly, long-term intake of many dietary foods (rich in phenolics) proved to be protective against the development and management of diabetes, cancer, osteoporosis, cardiovascular diseases and neurodegenerative diseases, etc.

Conclusion

This review presents an overview of flavonoid compounds to use them as a potential therapeutic alternative in various diseases and disorders. In addition, the present understanding of phenolics and flavonoids will serve as the basis for the next scientific studies.

Suitability of Roselle-Hibiscus sabdariffa L. as Raw Material for Soft Drink Production

Consumption of conventional soft drinks has been linked with several diseases in man. This has called for the consumption of natural soft drinks such as roselle drink. Roselle-Hibiscus sabdariffa L. is the major raw material for the production of beverage called cranberry (Florida), bissap (Egypt), zobo (Nigeria), and roselle drink generally. The nutritional and phytochemical properties found in roselle make the plant useful in the preparation of some drugs and food. It has been reported that consumption of roselle drink helps to cure diseases such as high blood pressure and diabetes. The pharmacological properties of the plant are traceable to activities of flavonoid and anthocyanin which are the major antioxidants in roselle. Good aroma and colour of the drink are among the characteristics displayed by the plant. However, consumers are sometimes exposed to risks when the drink is consumed after 24 hours of preparation due to the proliferation of spoilage microorganisms in the drink. Most of these microbes thrive even at extreme temperatures. Unfortunately, some of these microorganisms are of public health importance causing diseases such as meningitis and dysentery. Researchers have revealed that roselle calyx is the major source of contamination in the drink. This paper reviews the suitability of the plant for soft drink production. It further highlights the nutrition, pharmacology, and limitations of the plant for soft drink production.

Effect of aqueous extract and anthocyanins of calyces of Hibiscus sabdariffa (Malvaceae) in rats with adenine-induced chronic kidney disease

OBJECTIVES

The aim of this work was to assess the possible beneficial effects of aqueous extracts of Hibiscus sabdariffa L. calyces and anthocyanins isolated therefrom in an adenine-induced chronic kidney disease (CKD) model.

METHODS

Rats were orally given, for 28 consecutive days, either adenine alone or together with either aqueous extract of H. sabdariffa calyces (5 and 10%) or anthocyanins (50, 100 and 200 mg/kg of anthocyanin concentrate). For comparative purposes, two groups of rats were given lisinopril (10 mg/kg).

KEY FINDINGS

When either H. sabdariffa aqueous extract or the anthocyanins isolated from it was administered along with adenine, the adverse effects of adenine-induced CKD were significantly lessened, mostly in a dose-dependent manner. The positive effects were similar to those obtained by administration of lisinopril.

CONCLUSIONS

The results obtained show that both H. sabdariffa and its anthocyanins could be considered as possible promising safe dietary agents that could be used to attenuate the progression of human CKD. This could have added significance as H. sabdariffa tea is widely consumed in many parts of Africa and Asia and is thus readily available.

Phytochemical Content, Health Benefits, and Toxicology of Common Edible Flowers: A Review (2000-2015)

Edible flowers contain numerous phytochemicals which contribute to their health benefits, and consumption of edible flowers has increased significantly in recent years. While many researchers have been conducted, no literature review of the health benefits of common edible flowers and their phytochemicals has been compiled. This review aimed to present the findings of research conducted from 2000 to 2015 on the species, traditional application, phytochemicals, health benefits, and the toxicology of common edible flowers. It was found in 15 species of common edible flowers that four flavonols, three flavones, four flavanols, three anthocyanins, three phenolic acids and their derivatives were common phytochemicals and they contributed to the health benefits such as anti-oxidant, anti-inflammatory, anti-cancer, anti-obesity, and neuroprotective effect. Toxicology studies have been conducted to evaluate the safety of common edible flowers and provide information on their dosages and usages.

Chinese medicines in the treatment of experimental diabetic nephropathy

Diabetic nephropathy (DN) is a severe micro vascular complication accompanying diabetes mellitus that affects millions of people worldwide. End-stage renal disease occurs in nearly half of all DN patients, resulting in large medical costs and lost productivity. The course of DN progression is complicated, and effective and safe therapeutic strategies are desired. While the complex nature of DN renders medicines with a single therapeutic target less efficacious, Chinese medicine, with its holistic view targeting the whole system of the patient, has exhibited efficacy for DN management. This review aims to describe the experimental evidence for Chinese medicines in DN management, with an emphasis on the underlying mechanisms, and to discuss the combined use of herbs and drugs in DN treatment.

Management of diabetic complications: a chemical constituents based approach

ETHNOPHARMACOLOGICAL RELEVANCE

Long term hyperglycemia leads to development of complications associated with diabetes. Diabetic complications are now a global health problem without effective therapeutic approach. Hyperglycemia and oxidative stress are important components for the development of diabetic complications. Over the past few decades, herbal medicines have attracted much attention as potential therapeutic agents in the prevention and treatment of diabetic complications due to their multiple targets and less toxic side effects. This review aims to assess the current available knowledge of medicinal herbs for attenuation and management of diabetic complications and their underlying mechanisms.

MATERIAL AND METHODS

Bibliographic investigation was carried out by scrutinizing classical text books and peer reviewed papers, consulting worldwide accepted scientific databases (SCOPUS, PUBMED, SCIELO, NISCAIR, Google Scholar) to retrieve available published literature. The inclusion criteria for the selection of plants were based upon all medicinal herbs and their active compounds with attributed potentials in relieving diabetic complications. Moreover, plants which have potential effect in ameliorating oxidative stress in diabetic animals have been included.

RESULTS

Overall, 238 articles were reviewed for plant literature and out of the reviewed literature, 127 articles were selected for the study. Various medicinal plants/plant extracts containing flavonoids, alkaloids, phenolic compounds, terpenoids, saponins and phytosterol type chemical constituents were found to be effective in the management of diabetic complications. This effect might be attributed to amelioration of persistent hyperglycemia, oxidative stress and modulation of various metabolic pathways involved in the pathogenesis of diabetic complications.

CONCLUSION

Screening chemical candidate from herbal medicine might be a promising approach for new drug discovery to treat the diabetic complications. There is still a dire need to explore the mechanism of action of various plant extracts and their toxicity profile and to determine their role in therapy of diabetic complications. Moreover, a perfect rodent model which completely mimics human diabetic complications should be developed.

Polyphenols of Hibiscus sabdariffa improved diabetic nephropathy via attenuating renal epithelial mesenchymal transition

We previously reported that Hibiscus sabdariffa polyphenol extracts (HPE) are beneficial for diabetic nephropathy. Since an epithelial to mesenchymal transition (EMT) is critical in renal fibrosis, the present study aimed to investigate whether HPE could prevent EMT of tubular cells. Treatment of HPE reduced angiotensin II receptors (AT)-1 and transforming growth factor β1 (TGF-β1) evoked by high glucose and recovered the increased vimentin and decreased E-cadherin. HPE decreased fibronectin, thus avoiding EMT and accompanying fibrosis. AT-1 was upstream to TGF-β1, while there were recruitment signals between AT-1 and TGF-β1. Scan electron microscopy (SEM) and immunohistochemistry (IHC) revealed that the interacting filaments of tubular cells disappeared when treated with high glucose, and type IV collagen of tubulointerstitial decreased in diabetic kidneys. Treatment of HPE recovered morphological changes of cell junction and basement membrane. We suggest that HPE has the potential to be an adjuvant for diabetic nephropathy by regulating AT-1/TGF-β1 and EMT.

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.

Peptide isolated from Japanese flounder skin gelatin protects against cellular oxidative damage

Gelatin was extracted from the skin of Japanese flounder ( Palatichtys olivaceus ) and was subjected to enzymatic hydrolysis. The peptic hydrolysate resulted in a potent antioxidative peptide Gly-Gly-Phe-Asp-Met-Gly (582 Da), which bears +12.61 kcal/mol hydrophobicity. The antioxidative potential of the peptide was characterized by analyzing the protective effect of the peptide on reactive oxygen species (ROS)-mediated intracellular macromolecule damage. It was found that the peptide is a potent scavenger of intracellular ROS, thereby protecting the radical-mediated damage of membrane lipids, proteins, and DNA. Moreover, the peptide is capable of upregulating the expression of inherent antioxidative enzymes, superoxide dismutase-1, glutathione, and catalase. Collectively, it can be concluded that Japanese flounder skin, a processing byproduct of filleting, can be effectively used to produce a bioactive peptide with potent antioxidant capacity.

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

H. sabdariffa polyphenolic extract (HPE) was demonstrated to inhibit high glucose-stimulated cellular changes. In this study, we analyzed the composition of HPE and used a type 2 diabetic rat model to test its protective effect. At least 18 phenolic compounds were found in HPE. Treatment with HPE reduced hyperglycemia and hyperinsulinemia, especially at the dose of 200 mg/kg. HPE decreased serum triacylglycerol, cholesterol, and the ratio of low density lipoprotein/high density lipoprotein (LDL/HDL). Diabetes promoted plasma advanced glycation end product (AGE) formation and lipid peroxidation, while HPE significantly reduced these elevations. Immunohistological observation revealed that HPE inhibited the expression of connective tissue growth factor (CTGF) and receptor of AGE (RAGE), which was increased in type 2 diabetic aortic regions. Furthermore, HPE recovered the weight loss found in type 2 diabetic rats. In conclusion, we demonstrated the anti-insulin resistance properties of HPE and its effect on hypoglycemia, hypolipidemia, and antioxidation. HPE has the potential to be an adjuvant for diabetic therapy.

Plant polyphenols as dietary antioxidants in human health and disease

Polyphenols are secondary metabolites of plants and are generally involved in defense against ultraviolet radiation or aggression by pathogens. In the last decade, there has been much interest in the potential health benefits of dietary plant polyphenols as antioxidant. Epidemiological studies and associated meta-analyses strongly suggest that long term consumption of diets rich in plant polyphenols offer protection against development of cancers, cardiovascular diseases, diabetes, osteoporosis and neurodegenerative diseases. Here we present knowledge about the biological effects of plant polyphenols in the context of relevance to human health.

Isoliquiritigenin entails blockade of TGF-beta1-SMAD signaling for retarding high glucose-induced mesangial matrix accumulation

Diabetic nephropathy characterized as mesangial fibrosis and glomerulosclerosis results in renal failure and end-stage renal diseases. Enhanced expression and secretion of connective tissue growth factor (CTGF) play an important role in the expansion of glomerular mesangial matrix mostly composed of type IV collagen. Isoliquiritigenin can prevent various renal injuries via its anti-inflammatory action. However, the effect of isoliquiritigenin on diabetic nephropathy has never been explored. The present study was to investigate whether nontoxic isoliquiritigenin inhibited high glucose (HG)-induced mesangial fibrosis by retarding formation of type IV collagen as well as CTGF in human mesangial cells (HRMC). Serum starved cells were cultured in media containing 5.5 mM glucose plus 27.5 mM mannitol as an osmotic control or 33 mM glucose for 3 days with and without 1-20 microM isoliquiritigenin. Exposure of cells to HG caused marked increases in collagen secretion and CTGF expression, which was dose-dependently reversed by isoliquiritigenin at the transcriptional levels. Additionally, isoliquiritigenin boosted HG-plummeted type matrix metalloproteinase-1 (MT-1 MMP) expression and dampened HG-elevated tissue inhibitor of MMP-2 (TIMP-2) expression, facilitating the degradation of mesangial matrix. Isoliquiritigenin inhibited HG-upregulated CTGF and TIMP-2 expression via disturbing TGF-beta1 signaling in HRMC, as evidenced by TGF-beta receptor I kinase (TGF-beta RI) inhibitor. HG-activated SMAD2 through autocrine TGF-beta signaling was repealed by > or =10 microM isoliquiritigenin. HG induced SMAD4 expression of HRMC and obliterated antagonistic SMAD7, whereas isoliquiritigenin suppressed induction of TGF-beta RII and TGF-beta RI with blunting their downstream SMAD signaling. The results demonstrate that the bioactive isoliquiritigenin in licorice diminished mesangial matrix accumulation in response to ambient HG through retarding TGF-beta1-SMAD signaling transduction. Therefore, isoliquiritigenin may be a potential therapeutic agent for the prevention and treatment of mesangial fibrosis and glomerulosclerosis leading to diabetic nephropathy due to longstanding diabetes mellitus.

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

BACKGROUND

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

RESULTS

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

CONCLUSION

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