Amaya Aleixandre

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.

Short-term effect of egg-white hydrolysate products on the arterial blood pressure of hypertensive rats.

In the present study we evaluate the blood pressure-lowering effect of the following products: the hydrolysate obtained from egg white (EW) by enzymatic treatment with pepsin (HEW), the peptide fraction of HEW with molecular mass lower than 3000 Da (HEW<3000 Da), and three peptide sequences isolated from HEW<3000 Da (Tyr-Ala-Glu-Glu-Arg-Tyr-Pro-Ile-Leu: YAEERYPIL); (Arg-Ala-Asp-His-Pro-Phe-Leu: RADHPFL); and (Ile-Val-Phe (IVF)). These peptides, and also HEW and HEW<3000 Da, had been characterized previously in vitro as potent inhibitors of angiotensin-converting enzyme (ACE). EW and the products mentioned earlier were orally administered by gastric intubation, to 17-20-week-old male spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto (WKY) rats. We measured the systolic blood pressure (SBP) and the diastolic blood pressure (DBP) of the rats by the tail cuff method before administration and also 2, 4, 6, 8 and 24 h post-administration. Distilled water served as negative control, and we used captopril (50 mg/kg) as positive control to carry out similar experiments with a known ACE inhibitor. HEW, HEW<3000 Da and the three peptide sequences decreased SBP and DBP in SHR but they did not modify these variables in WKY rats. The peptide sequences YAEERYPIL, RADHPFL and IVF showed a potency to decrease blood pressure greater than HEW or HEW<3000 Da. The results obtained suggest that the studied products could be used as a functional food with potential therapeutic benefit in the prevention and treatment of hypertension.

Effect of the long-term intake of an egg white hydrolysate on the oxidative status and blood lipid profile of spontaneously hypertensive rats.

This paper examines the effects of the long-term consumption of egg white hydrolysed with pepsin (hEW) on the antioxidant status and lipid profile of spontaneously hypertensive rats (SHR). The antioxidant capacity was measured by the oxygen radical absorbance capacity (ORAC) and the oxidative status by the malon-dialdehyde (MDA) assay. The lipid profile was analysed spectrophotometrically. The radical-scavenging capacity of the plasma was increased and the MDA concentration in the aorta was decreased in the SHR treated with 0.5g/kg/day of hEW. Our findings indicate that hEW played an important role in antioxidative defence of SHR and exerted a beneficial effect on the lipid profile, lowering triglycerides and total cholesterol without changing HDL levels. Therefore, hEW may be useful to prevent or reverse abnormalities associated with the metabolic syndrome and its complications, such as hypertension, oxidative stress and hyperlipidemia.

Antihypertensive effect of a polyphenol-rich cocoa powder industrially processed to preserve the original flavonoids of the cocoa beans.

A natural flavonoid-enriched cocoa powder, commercially named CocoanOX and developed via a patented industrial process, was characterized and tested for a possible antihypertensive effect. The bioavailability of this polyphenol-rich cocoa powder developed at pilot scale was previously demonstrated in humans. The present results showed that this product was very rich in total procyanidins (128.9 mg/g), especially monomers, dimers, and trimers (54.1 mg/g), and mainly (-)-epicatechin (19.36 mg/g). The effect of a single oral administration of CocoanOX in spontaneously hypertensive rats (SHR) was evaluated at different doses (50, 100, 300, and 600 mg/kg). This product produced a clear antihypertensive effect in these animals, but these doses did not modify the arterial blood pressure in the normotensive Wistar-Kyoto rats. Paradoxically, the maximum effect in the systolic blood pressure (SBP) of SHR was caused by 300 mg/kg of CocoanOX. This dose brought about a decrease in this variable very similar to that caused by 50 mg/kg Captopril. It was also surprising that the maximum effect in the diastolic blood pressure (DBP) was caused by 100 mg/kg CocoanOX. The initial values of DBP and SBP were recovered in SHR, respectively, 24 and 48 h postadministration of the different doses of CocoanOX or Captopril. These results suggest that CocoanOX could be used as a functional ingredient with antihypertensive effect, although it would be also necessary to carry out bioavailability and clinical studies to demonstrate its long-term antihypertensive efficiency in humans.

Dietary Fiber in the Prevention and Treatment of Metabolic Syndrome: A Review

Inclusion of fiber in the diet has been linked to the prevention of a range of illnesses and conditions. This review contains several ideas about the possible benefits of dietary fiber intake in patients with metabolic syndrome. The principal beneficial effects of a fiber-rich diet in these patients are: prevention of obesity, improved glucose levels, and control of the profile of blood lipids. We now also know that dietary fiber may favor the control of arterial blood pressure. Animal experiments have also shown the benefit of different types of fiber on these variables. Of particular relevance are the studies using obese Zucker rats, which present similar anomalies to those seen in patients with metabolic syndrome. There is therefore a growing interest in discovering new sources of natural fiber. Some of these different kinds of fiber may then be used as functional ingredients to obtain foods with properties that are beneficial to health.

Changes in arterial blood pressure after single oral administration of milk‐casein‐derived peptides in spontaneously hypertensive rats

In this study we evaluated the short-term oral antihypertensive effect of several peptide sequences isolated from casein fractions, previously characterized as in vitro angiotensin-converting enzyme-inhibitors, in spontaneously hypertensive rats (SHR). Systolic blood pressure (SBP) and the diastolic blood pressure (DBP) of the rats were measured by the tail cuff method before administration and also 2, 4, 6, 8 and 24 h post-administration. The sequences LVYPFTGPIPN, HLPLP, IAK, YAKPVA and WQVLPNAVPAK showed a clear decrease in SBP and DBP in SHR. HPHPHLSF caused a significant decrease of the DBP in the SHR, but this sequence did not modify the SBP of these animals in a significant manner. KKYNVPQL did not modify SBP in the SHR, and caused a slight, but significant and maintained, decrease in DBP in these animals. SBP and DBP returned to baseline values 24 h post-administration of all peptides. In conclusion, these peptides are bioactive ingredients with potential benefit in the prevention and treatment of hypertension or other associated disorders.

Highly Methoxylated Pectin Improves Insulin Resistance and Other Cardiometabolic Risk Factors in Zucker Fatty Rats

In this study, we evaluated the effect of a highly methoxylated apple pectin (HMAP) on cardiometabolic risk factors in Zucker fatty rats. beta-Glucan, a fiber known for its hypocholesterolemic properties, also was used. The rats fed both fiber-enriched diets exhibited a reduction in body weight and in total cholesterol and triglycerides when compared to the Zucker fatty rats fed the standard diet. The effect on the lipid profile was more remarkable in the HMAP group. A decrease in blood glucose was only noticed in this group. Moreover, a decrease in plasma insulin, HOMA-IR, and HOMA-beta was noticed in the fiber groups, and in particular in the HMAP group, these variables being similar to the lean rats. Blood pressure and endothelial function were similar in all the Zucker fatty rats. These results warrant evaluation in humans to determine if HMAP could be used as a functional ingredient to reduce lipid profile, insulin resistance, and other cardiometabolic risk factors.

Soluble fiber-enriched diets improve inflammation and oxidative stress biomarkers in Zucker fatty rats

In this study we evaluated the effect of the administration of different soluble fiber enriched-diets on inflammatory and redox state of Zucker fatty rats. Four groups of ten 8 week-old female Zucker fatty rats were used. The four groups were respectively fed the following diets until the 15th week of life: standard diet (obese control), 10% high methoxylated apple pectin (HMAP)-, 5% soluble cocoa fiber (SCF)-, and 10% β-glucan-enriched diets. A group of Zucker lean rats fed the standard diet was also used as control for normal values of this rat strain. The plasma levels of tumoral necrosis factor-α (TNF-α), adiponectin, and malondialdehyde (MDA) were measured at the end of treatment. The reduced glutathione liver levels were also obtained at that moment. TNF-α plasma levels decreased somewhat in Zucker fatty rats fed the different fibers, and MDA plasma levels significantly decreased in these animals. Nevertheless, adiponectin plasma levels increased in the Zucker fatty rats fed the SCF enriched diet, but did not change in the HMAP and the β-glucan group. The Zucker fatty rats fed the different fiber showed a trend towards increased the reduced glutathione liver levels, but significant differences with obese control rats were only obtained in the β-glucan group. The results obtained in this study suggest that the intake of the different soluble fiber-enriched diets that we have evaluated could prevent and/or attenuate the inflammatory and/or the prooxidative state of the metabolic syndrome.

Changes in arterial blood pressure of a soluble cocoa fiber product in spontaneously hypertensive rats.

The effect produced by long-term intake of a soluble cocoa fiber product (SCFP) on the development of hypertension of spontaneously hypertensive rats (SHR) was evaluated. Twenty male 3-week-old SHR were divided into two groups of 10 animals that drank either tap water (control) or a solution of SCFP (0.75 g/day SCFP) until the 20th week of life. Five 20-week-old rats of each group were sacrificed. Tap water as drinking fluid was given to all the animals from the 20th to 24th week of life. The 24-week-old rats were also sacrificed. Body weight, liquid and dry food intake, and arterial blood pressure (tail cuff) were recorded weekly. Malondialdehyde (MDA), glucose and angiotensin converting enzyme (ACE) activity in the plasma from the sacrificed rats were also obtained, and we evaluated the relaxation caused by acetylcholine in the aorta from these animals. SCFP attenuated the development of hypertension in SHR; however, the withdrawal of SCFP caused an increase in blood pressure in the rats. Body weight gain was slower in the group treated with SCFP. SCFP increased liquid intake but decreased dry food intake in the rats. SCFP decreased plasma MDA concentrations and slightly decreased plasma ACE activity, but no differences were observed in plasma glucose and in the aorta responses to acetylcholine in both groups of 20-week-old SHR. We have demonstrated the antihypertensive and antioxidant properties of SCFP. The control of body weight and the control of increased angiotensin II may be involved in the antihypertensive effect of this product.

Effect of a Soluble Cocoa Fiber-Enriched Diet in Zucker Fatty Rats

The effects of a soluble cocoa fiber (SCF) were studied in Zucker fatty rats. Two groups of Zucker fatty rats were fed the following diets: standard diet and 5% SCF-enriched diet. A group of Zucker lean rats fed the standard diet was used for results comparison with obese Zucker animals. Solid and liquid intakes, body weight, plasma glucose, lipid profile, and systolic (SBP) and diastolic (DBP) blood pressure were recorded weekly. At the end of the experimental period insulin was determined, and fat apparent digestibility (FAD) and insulin resistance were calculated. The Zucker fatty rats fed 5% SCF-enriched diet showed less weight gain and food intake than those fed the standard diet. The group fed the fiber-enriched diet showed lower values of the total cholesterol/high-density lipoprotein cholesterol ratio and triglyceride levels than the standard group. FAD was also lower in the fiber group. Both SBP and DBP were decreased. In addition, SCF reduced plasma glucose and insulin, and as a consequence the insulin resistance was also decreased. Our data demonstrate that SCF resulted in an improvement of the studied risk factors associated with cardiometabolic disorders.