[Cellular mechanism of vasculo-protection induced by polyphenols on the endothelium]

Antidiabetic activity of the aqueous extract of Erigeron floribundus leaves in streptozotocin-induced type 1 diabetes model in Wistar rats

Backgroud

Erigeron floribundus is a herbaceous plant used in traditional Cameroonian medicine to treat diabetes mellitus. The aim of this study was to evaluate the antidiabetic properties of the aqueous extract of E. floribundus leaves (AEEF) in diabetic rats.

Methods

Diabetes was induced by a single intraperitoneal injection of streptozotocin (60 mg/kg) in normal rats fasted for 16 h. Subsequently, 30 diabetic male rats were divided into groups and treated orally for 21 days with distilled water (10 mL/kg), glibenclamide (3 mg/kg) and AEEF (300, 400, and 500 mg/kg). Body weight, food and water intake, blood glucose, insulin levels, lipid and oxidative profiles, as well as some markers of liver and kidney function were assessed. Histological sections of the rats' pancreas were taken.

Results

AEEF and glibenclamide significantly increased (p < 0.001) body weight and decreased food and water intake in rats. A decrease in blood glucose (p < 0.001) and an increase in insulin levels (p < 0.001) were observed in the AEEF and glibenclamide groups. AEEF caused a significant (p < 0.001) decrease in the levels of total cholesterol, LDL-c, triglycérides and coronary risk index (CRI), accompanied by a significant (p < 0.001) increase in HDL levels and HOMA-β in rats. AEEF showed an improvement (p < 0.001) in CAT and SOD activity and GSH levels accompanied by a significant decrease (p < 0.001) in malondialdehyde levels. In addition, ALAT and ASAT activity, urea and creatinine levels were significantly reduced (p < 0.001) after treatment with AEEF and glibenclamide. The extract also improved the size of Langerhans Islets in the pancreas of diabetic rats.

Conclusion

AEEF contains several bioactive compounds conferring antidiabetic, anti-dyslipidemic and antioxidant properties, thus justifying its therapeutic use in the treatment of diabetes mellitus.

Myricitrin exhibits anti-atherosclerotic and anti-hyperlipidemic effects in diet-induced hypercholesterolemic rats

The present study investigated the anti-atherosclerotic potential of myricitrin in hypercholesterolemic rats. Rats were divided into the following groups: sham (standard food), control [1% high-cholesterol diet (HCD)], 1 μM myricitrin + 1% HCD, 10 μM myricitrin + 1% HCD, 100 μM myricitrin + 1% HCD, and the positive control (10 mg/kg body weight atorvastatin). The dose was given to rats via oral gavage for 45 consecutive days. Feeding of rats with 1% HCD caused substantial increases in the levels of LDL, cholesterol, and triglycerides (TG), while high-density lipoprotein (HDL) was reduced. However, rats supplemented with myricitrin had reduced levels of cholesterol, LDL, and TG to near-normal levels, whereas HDL was increased. Catalase, superoxide dismutase (SOD), glutathione peroxidase (Gpx), and reduced glutathione (GSH) levels were substantially reduced in the HCD-fed rats compared with sham rats. However, the rats supplemented with 100 μM myricitrin showed > 50% increases in these levels. Lipid peroxidation and reactive oxygen species (ROS) levels were reduced following myricitrin treatment. The aortic cell wall area was significantly increased by 14.5% in HCD-fed rats. However, rats supplemented with 1, 10, and 100 μM myricitrin showed significant reductions in the aortic cell wall area of 2.3%, 4%, and 27.5%, respectively. This is the first report of the anti-atherosclerotic and hypolipidemic effects of myricitrin in hypercholesterolemic rats. Myricitrin decreased the level of total serum cholesterol and the role of aortic atherosclerosis in hypercholesterolemic rats.

Is a Meal without Wine Good for Health?

Hippocrates, the father of medicine, had said: "Wine is a thing wonderfully appropriate to man if, in health as in disease, it is administered with appropriate and just measure according to the individual constitution." Wine has always accompanied humanity, for religion or for health. Christians and Jews need wine for the liturgy. For Plato, wine was an indispensable element in society and the most important in the symposium. In this second part of the banquet, mixed with water, the wine gave the word. If the French paradox made a lot of ink flow; it was the wine that was originally responsible for it. Many researchers have tried to study alcohol and polyphenols in wine, in order to solve the mystery. Beyond its cardiovascular effects, there are also effects on longevity, metabolism, cancer prevention, and neuroprotection, and the list goes on. The purpose of this work is to make an analysis of the current knowledge on the subject. Indeed, if the paradigm of antioxidants is seductive, it is perhaps by their prooxidant effect that the polyphenols act, by an epigenetic process mediated by nrf2. Wine is a preserve of antioxidants for the winter and it is by this property that the wine acts, in an alcoholic solution. A wine without alcohol is pure heresy. Wine is the elixir that by design, over millennials, has acted as a pharmacopeia that enabled man to heal and prosper on the planet. From Alvise Cornaro to Serge Renaud, nutrition was the key to health and longevity, whether the Cretan or Okinawa diet, it is the small dose of alcohol (wine or sake) that allows the bioavailability of polyphenols. Moderate drinking gives a protection for diseases and a longevity potential. In conclusion, let us drink fewer, but drink better, to live older.

Therapeutic Role of Resveratrol and Quercetin on Aortic Fibroblasts of Psammomys obesus After Oxidative Stress by Hydrogen Peroxide

In our study, we propose to analyze the effects of resveratrol (RES) and quercetin (QRC) on proliferation markers, oxidative stress, apoptosis, and inflammation of aortic fibroblasts of Psammomys obesus after induced oxidative stress by hydrogen peroxide (H2O2). Fibroblasts were incubated in RES 375 μM and QRC 0.083 μM for 24 hours after exposure to H2O2 1.2 mM for 6 hours. We performed the proliferation rate, cells viability, morphological analyses, cytochrome c, Akt, ERK1/2, and p38 MAPK quantification. The redox status was achieved by proportioning of malondialdehyde, nitric monoxide, advanced oxidation protein products, carbonyl proteins, catalase, and superoxide dismutase activity. The inflammation was measured by TNFα, MCP1, and NF-kB assay. The extracellular matrix (ECM) remodeling was performed by SDS-PAGE. Stressed fibroblasts showed a decrease of cell proliferation and viability, hypertrophy and oncosis, chromatin hypercondensation and increase of cytochrome c release characteristic of apoptosis, activation of ERK1/2 and Akt pathway, and decreases in p38 MAPK pathways marking the cellular resistance. The redox state was disrupted by increased malondialdehyde, nitric monoxide, advanced oxidation protein products, carbonyl protein production, catalase and superoxide dismutase activity, and a decreased production of proteins including collagens. Inflammation state was marked by MCP-1, TNFα, and NF-kB increase. Treatment of fibroblasts stressed by RES and QRC inverted the oxidative stress situation decreasing apoptosis and inflammation, and improving the altered redox status and rearrangement of disorders observed in extracellular matrix. H2O2 induced biochemical and morphological alterations leading to apoptosis. An improved general condition is observed after treatment with RES and QRC; this explains the antioxidant and antiapoptotic effects of polyphenols.

The anticonvulsant effect of a polysaccharide-rich extract from Genipa americana leaves is mediated by GABA receptor

BACKGROUND

This study aimed to chemically characterize a polysaccharide-rich extract (PRE) obtained from Genipa americana leaves and evaluate its neuroprotective effect in the brain morphology and oxidative markers using mice behavioral models.

METHODS

Dry powder (5 g) of G. americana leaves were submitted to depigmentation in methanol. PRE was obtained by extraction in NaOH and precipitation with absolute ethanol and characterized by infrared spectroscopy (FTIR) and nuclear magnetic resonance (¹H and ¹³C NMR). Swiss mice (25-35 g) received saline (0.9% NaCl) or PRE (1-27 mg/kg) by intraperitoneal (i.p.) route, 30 min before evaluation in behavioral models (open field, elevated plus maze, sleeping time, tail suspension, forced swimming, seizures induced by pentylenetetrazole-PTZ). Animal's brain were dissected and analyzed for histological alterations and oxidative stress.

RESULTS

FTIR spectrum showed bands around 3417 cm^-1 and 2928 cm^-1, relative to the vibrational stretching of OH and CH, respectively. ¹H NMR spectrum revealed signals at δ 3.85 (methoxyl groups) and δ 2.4 (acetyl) ppm. ¹³C NMR spectrum revealed signals at δ 108.0 and δ 61.5 ppm, corresponding to C1 and C5 of α-L-arabinofuranosyl residues. PRE presented central inhibitory effect, increasing the latency for PTZ-induced seizures by 63% (9 mg/kg) and 55% (27 mg/kg), and the latency to death by 73% (9 mg/kg) and 72% (27 mg/kg). Both effects were reversed by the association with flumazenil.

CONCLUSIONS

PRE, containing a heteropolysaccharide, presents antioxidant and anticonvulsant effect in the model of PTZ-induced seizures via gamma-aminobutyric acid (GABA), decreasing the number of hippocampal black neurons.

Anti-hyperlipidemic and anti-atherosclerotic effects of Pinus eldarica Medw. nut in hypercholesterolemic rabbits

Background

Previous studies suggest that chemical constituents present in Pinus eldarica Medw (P. eldarica) nut possess antioxidant properties that may positively influence lipid profile.

The present study was conducted to evaluate the efficacy of P. eldarica nut on the experimental atherosclerosis development in hypercholesterolemic rabbits.

Methods

Forty male 6 months old white New Zealand rabbits (1.8–2 kg) were randomly assigned into five equal groups. One group was kept as control (normal) group, fed on standard rabbit diet and other 4 groups were fed on high cholesterol diet (HCD). Out of four HCD groups one group was kept as control (HCD) and other three groups were treated with different doses (50, 100 and 200 mg/kg/day) of P. eldarica nut for 8 weeks. Percentage of aortic wall area changes as indication of atherosclerosis development and fasting blood cholesterol, LDL, HDL and triglyceride levels were determined in all groups.

Results

The results indicate that fasting blood cholesterol and aortic atherosclerotic involvements in 200 mg/kg/day and 100 mg/kg/day P. eldarica nut extract treated groups significantly decreased as compared to the high cholesterol-diet control group.

Conclusion

P. eldarica nut lowers blood cholesterol level and aortic atherosclerotic involvement in hypercholesterolemic rabbits.

Beneficial effects of polyphenols on cardiovascular disease

In recent years, numerous studies have demonstrated the health benefits of polyphenols, and special attention has been paid to their beneficial effects against cardiovascular disease, the leading cause of death in the world today. Polyphenols present vasodilator effects and are able to improve lipid profiles and attenuate the oxidation of low density lipoproteins. In addition, they present clear anti-inflammatory effects and can modulate apoptotic processes in the vascular endothelium. It has been suggested that most of these effects are a consequence of the antioxidant properties of polyphenols, but this idea is not completely accepted, and many other mechanisms have been proposed recently to explain the health effects of these compounds. In fact, different signaling pathways have been linked to polyphenols. This review brings together some recent studies which establish the beneficial properties of polyphenols for cardiovascular disease and analyzes the mechanisms involved in these properties.

Cardiovascular protective effects of resveratrol

Resveratrol (3,4',5-trihydroxy-trans-stilbene), a phytoalexin found in grape skins, peanuts, and red wine, has been reported to have a wide range of biological and pharmacological properties. It has been speculated that at low doses (such as consumed in the common diet) resveratrol may have cardioprotective activity. In this article we describe recent in vitro and in vivo studies in animal models. The results of these studies suggest that resveratrol modulates vascular cell function, inhibits LDL oxidation, suppresses platelet aggregation and reduces myocardial damage during ischemia-reperfusion. Although the reported biological data indicate that resveratrol is a highly promising cardiovascular protective agent, more studies are needed to establish its bioavailability and in vivo cardioprotective effects, particularly in humans.

Extending applicability of the oxygen radical absorbance capacity (ORAC-fluorescein) assay

The ORAC-fluorescein (ORAC-FL) method recently validated using automatic liquid handling systems has now been adapted to manual handling and using a conventional fluorescence microplate reader. As calculated for Trolox, the precision of the method was <3.0, expressed as percent coefficient of variation. The accuracy of the method was <2.3, expressed as percent variation of the mean. The detection and quantification limits were those corresponding to 0.5- and 1-microM Trolox standard solutions, respectively. The method has been applied to 10 pure compounds (benzoic and cinnamic acids and aldehydes, flavonoids, and butylated hydroxyanisole), to 30 white, rose, and bottled- and oak-aged red wines, and to 7 commercial dietary antioxidant supplements. All samples exhibited a good linear response with concentration. As seen by other methodologies, the chemical structure of a compound determines its antioxidant activity (ORAC-FL value). Of particular interest were the results with oak-aged red wines from different vintages (1989-2002) that confirm influence of vintage, but not origin of the oak, in the antioxidant activity of wines from the same variety. Dietary antioxidant supplements presented a great variability (170-fold difference) in their antioxidant potency. This work proves applicability of the ORAC-FL assay in evaluating the antioxidant activity of diverse food samples.