Effects of pomace olive oil-enriched diets on endothelial function of small mesenteric arteries from spontaneously hypertensive rats

The Effect and Mechanism of Oleanolic Acid in the Treatment of Metabolic Syndrome and Related Cardiovascular Diseases

Metabolic syndromes (MetS) and related cardiovascular diseases (CVDs) pose a serious threat to human health. MetS are metabolic disorders characterized by obesity, dyslipidemia, and hypertension, which increase the risk of CVDs' initiation and development. Although there are many availabile drugs for treating MetS and related CVDs, some side effects also occur. Considering the low-level side effects, many natural products have been tried to treat MetS and CVDs. A five-cyclic triterpenoid natural product, oleanolic acid (OA), has been reported to have many pharmacologic actions such as anti-hypertension, anti-hyperlipidemia, and liver protection. OA has specific advantages in the treatment of MetS and CVDs. OA achieves therapeutic effects through a variety of pathways, attracting great interest and playing a vital role in the treatment of MetS and CVDs. Consequently, in this article, we aim to review the pharmacological actions and potential mechanisms of OA in treating MetS and related CVDs.

Increase in the Bioactive Potential of Olive Pomace Oil after Ultrasound-Assisted Maceration

Olive pomace oil is obtained when a mixture of olive pomace and residual water is subjected to a second centrifugation. This oil has small amounts of phenolic and volatile compounds compared with extra-virgin olive oil. This study aimed to promote the aromatization of olive pomace oil with rosemary and basil using ultrasound-assisted maceration (UAM) to increase its bioactive potential. For each spice, the ultrasound operating conditions (amplitude, temperature, and extraction time) were optimized through central composite designs. Free fatty acids, peroxide value, volatile compounds, specific extinction coefficients, fatty acids, total phenolic compounds, antioxidant capacity, polar compounds, and oxidative stability were determined. After obtaining the optimal maceration conditions assisted by ultrasound, pomace oils flavored with rosemary and basil were compared to pure olive pomace oil. Quality parameters and fatty acids showed no significant difference after UAM. Rosemary aromatization by UAM resulted in a 19.2-fold increase in total phenolic compounds and a 6-fold increase in antioxidant capacity, in addition to providing the most significant increase in oxidative stability. Given this, aromatization by ultrasound-assisted maceration is an efficient method to increase, in a short time, the bioactive potential of olive pomace oil.

Olive Pomace Oil versus High Oleic Sunflower Oil and Sunflower Oil: A Comparative Study in Healthy and Cardiovascular Risk Humans

Olive pomace oil (OPO) is mainly a source of monounsaturated fat together with a wide variety of bioactive compounds, such as triterpenic acids and dialcohols, squalene, tocopherols, sterols and aliphatic fatty alcohols. To date, two long-term intervention studies have evaluated OPO’s health effects in comparison with high oleic sunflower oil (HOSO, study-1) and sunflower oil (SO, study-2) in healthy and cardiovascular risk subjects. The present study integrates the health effects observed with the three oils. Two randomized, blinded, cross-over controlled clinical trials were carried out in 65 normocholesterolemic and 67 moderately hypercholesterolemic subjects. Each study lasted fourteen weeks, with two four-week intervention phases (OPO versus HOSO or SO), each preceded by a three-week run-in or washout period. Regular OPO consumption reduced total cholesterol (p = 0.017) and LDL cholesterol (p = 0.018) levels as well as waist circumference (p = 0.026), and only within the healthy group did malondialdehyde (p = 0.004) levels decrease after OPO intake versus HOSO. Contrarily, after the SO intervention, apolipoprotein (Apo) B (p < 0.001) and Apo B/Apo A ratio (p < 0.001) increased, and to a lower extent Apo B increased with OPO. There were no differences between the study groups. OPO intake may improve cardiometabolic risk, particularly through reducing cholesterol-related parameters and waist circumference in healthy and hypercholesterolemic subjects.

Edible oils from olive drupes as a source of bioactive pentacyclic triterpenes. Is there a prospect for a health claim authorization?

Virgin olive oil and olive-pomace oil constitute high nutritional value edible oils due to the presence of oleic acid and a variety of bioactives. Among the latter, the group of pentacyclic triterpenes (PcTr) is the least studied. This review provides an insight into the biosynthesis of PcTr in the olive fruit, mainly of oleanane-type, and the factors influencing their transfer to the oil. Particular attention is given to the extraction methods along with the liquid and gas chromatography coupled to mass spectrometry protocols used for the discrimination and determination of PcTr. The in vivo bioactive properties of PcTr through the intake of these oils against cardiovascular diseases, liver dysfunction, obesity and diabetes are presented with a prospect of a future health claim authorization. Gaps in literature are pointed out to support this goal.

Molecular Mechanisms Underlying the Effects of Olive Oil Triterpenic Acids in Obesity and Related Diseases

Dietary components exert protective effects against obesity and related metabolic and cardiovascular disturbances by interfering with the molecular pathways leading to these pathologies. Dietary biomolecules are currently promising strategies to help in the management of obesity and metabolic syndrome, which are still unmet medical issues. Olive oil, a key component of the Mediterranean diet, provides an exceptional lipid matrix highly rich in bioactive molecules. Among them, the pentacyclic triterpenic acids (i.e., oleanolic acid) have gained clinical relevance in the last decade due to their wide range of biological actions, particularly in terms of vascular function, obesity and insulin resistance. Considering the promising effects of these triterpenic compounds as nutraceuticals and components of functional foods against obesity and associated complications, the aim of our review is to decipher and discuss the main molecular mechanisms underlying these effects driven by olive oil triterpenes, in particular by oleanolic acid. Special attention is paid to their signaling and targets related to glucose and insulin homeostasis, lipid metabolism, adiposity and cardiovascular dysfunction in obesity. Our study is aimed at providing a better understanding of the impact of dietary components of olive oil in the long-term management of obesity and metabolic syndrome in humans.

Cardiovascular Effects Induced by Fruit Peels from Passiflora edulis in Hypertensive Rats and Fingerprint Analysis by HPLC-ESI-MSn spectrometry

Hypertension is a chronic disease and a global health problem. Due to its high prevalence, it constitutes the most important risk factor for cardiovascular disease. Fruit peels from Passiflora edulis fo. flavicarpa are rich in bioactive natural compounds that may have action in hypertension. This study aimed to perform a fingerprinting analysis of Passiflora edulis fruit peel extract and evaluate its actions on the cardiovascular system in an in vivo model. The extract was obtained from the dried and powdered fruit peels of Passiflora edulis. Glycoside flavonoids were identified in the extract by HPLC-ESI-MSⁿ. The extract showed a significant hypotensive effect after 28 days of treatment and improved vascular function in the mesenteric artery. This effect was verified by decreased vascular hypercontractility and increased vasorelaxant in response to sodium nitroprusside and acetylcholine. There was also a decrease in endothelial dysfunction, which can be attributed to nitric oxide's increased bioavailability. Thus, we hypothesize that all these effects contributed to a reduction in peripheral vascular resistance, leading to a significant hypotensive effect. These results are novel for fruit peels from P. edulis. Also, there was a decrease in plasma and cardiac malondialdehyde levels and an increase in glutathione, suggesting a reduction in oxidative stress, as well as an increase of anti-inflammatory cytokines such as IL-10 in the plasma. This study demonstrated that the extract can be a new source of raw material to be applied as food or medicine adjuvant for treating hypertension.

Effects of oleuropein on rat's atria and thoracic aorta: a study of antihypertensive mechanisms

Oleuropein (OLE) is the main bioactive ingredient in the leaves of the olive plant Olea europaea L. (Oleaceae), which has proven beneficial due to the antiinflammatory, antiatherogenic, anticancer, antimicrobial, and antiviral effects. This study aimed to investigate the antihypertensive and vasodilator potential of OLE by analyzing its acute effects on spontaneous atrial contractions and vasomotor responses of the isolated thoracic aorta in rats. We showed that the application of OLE induces negative chronotropic and inotropic effects on the heart. OLE also causes mild aortic vasodilation given that the maximal reduction in tension of intact aortic rings precontracted with phenylephrine was approximately 30%. This vasodilation is likely dependent on the nitric oxide released from the endothelium based on the effect obtained on denuded and phenylephrine precontracted aortic rings and responses reordered following vasoconstriction induced by high concentrations of K⁺ and heparin. Our findings provide a basis for further testing of OLE cardiovascular effects, which may lead to subsequent clinical research for its application in the treatment of hypertension and heart disease.

A review on management of cardiovascular diseases by olive polyphenols

Noncommunicable diseases have increasingly grown the cause of morbidities and mortalities worldwide. Among them, cardiovascular diseases (CVDs) continue to be the major contributor to deaths. CVDs are common in the urban community population due to the substandard living conditions, which have a significant impact on the healthcare system, and over 23 million human beings are anticipated to suffer from the CVDs before 2030. At the moment, CVD physicians are immediately advancing both primary and secondary prevention modalities in high-risk populations. The cornerstone of CVD prevention is a healthy lifestyle that is more cost-effective than the treatments after disease onset. In fact, in the present scenario, comprehensive research conducted on food plant components is potentially efficacious in reducing some highly prevalent CVD risk factors, such as hypercholesterolemia, hypertension, and atherosclerosis. Polyphenols of olive oil (OO), virgin olive oil (VOO), and extra virgin olive oil contribute an essential role for the management of CVDs. Olive oil induces cardioprotective effects due to the presence of a plethora of polyphenolic compounds, for example, oleuropein (OL), tyrosol, and hydroxytyrosol. The present study examines the bioavailability and absorption of major olive bioactive compounds, for instance, oleacein, oleocanthal, OL, and tyrosol. This review also elucidates the snobbish connection of olive polyphenols (OP) and the potential mechanism involved in combating various CVD results taken up from the in vitro and in vivo studies, such as animal and human model studies.

Pomace Olive Oil Concentrated in Triterpenic Acids Restores Vascular Function, Glucose Tolerance and Obesity Progression in Mice

Pomace olive oil, an olive oil sub-product, is a promising source of bioactive triterpenoids such as oleanolic acid and maslinic acid. Considering the vascular actions of pomace olive oil and the potential effects of the isolated oleanolic acid on metabolic complications of obesity, this study investigates for the first time the dietary intervention with a pomace olive oil with high concentrations of the triterpenic acids (POCTA), oleanolic and maslinic acid, during diet-induced obesity in mice. The results demonstrate that obese mice, when switched to a POCTA-diet for 10 weeks, show a substantial reduction of body weight, insulin resistance, adipose tissue inflammation, and particularly, improvement of vascular function despite high caloric intake. This study reveals the potential of a functional food based on pomace olive oil and its triterpenic fraction against obesity progression. Our data also contribute to understanding the health-promoting effects attributable to the Mediterranean diet.

Nutritional and other health properties of olive pomace oil

Olive-pomace oil is rich in oleic acid, and thus it can be an interesting dietary fat alternative as it can allow reaching the recommendation of consuming 20% of total diet energy in the form of monounsaturated fatty acids. In addition, olive-pomace oil also contains a wide range of minor components that may contribute to its healthy properties. The major components identified with healthy properties are triterpenic dialcohols and acids, squalene, tocopherols, sterols, fatty alcohols and phenolic compounds. The refining process, that the crude pomace-oil must undergo for commercial purposes, significantly reduces the content of phenolic compounds, while the other minor components remain at concentrations which can induce positive health effects, especially on cardiovascular health, outstanding pentacyclic triterpenes and aliphatic fatty alcohols in olive-pomace oil. Numerous in vitro and preclinical studies support that mainly the pure compounds, or extracts isolated from plant sources, play an important role in preventing cardiovascular disease and risk factors. Likewise, tocopherols, squalene and phytosterols, in addition to the minor fraction of phenolic compounds, have shown high biological activity with particular association to the cardiovascular function. In the light of the foregoing, and taking into consideration the absence of clinical studies with olive-pomace oil, it would be of great interest to develop randomized, crossover, controlled, double-blind studies to extend the knowledge and understanding on the health effects of olive-pomace olive.

Cardioprotective Effect of a Virgin Olive Oil Enriched with Bioactive Compounds in Spontaneously Hypertensive Rats

Olive oil and its derivatives have been described to exert beneficial effects on hypertensive states and cardiovascular disease prevention. We studied the effects of chronic consumption of extra virgin olive oil (EVOO), enriched in bioactive compounds from olive fruit and leaves, on blood pressure, endothelial function, oxidative and inflammatory status, and circulating cholesterol levels, in spontaneously hypertensive rats (SHR). Thirty SHR were randomly assigned to three groups: a control untreated SHR group, an SHR group (1 mL/rat/day) of a control olive oil (17.6 mg/kg of phenolic compounds), and an SHR group (1 mL/rat/day) of the enriched EVOO (750 mg/kg of phenolic compounds) for eight weeks. Ten Wistar Kyoto rats (WKY) were included as healthy controls. Long-term administration of the enriched EVOO decreased systolic blood pressure and cardiac hypertrophy, and improved the ex vivo aortic endothelial dysfunction measured in SHR. Moreover, enriched oil supplementation reduced the plasma levels of Angiotensin II and total cholesterol, and the urinary levels of endothelin-1 and oxidative stress biomarkers, while pro-inflammatory cytokines were unaffected. In conclusion, sustained treatment with EVOO, enriched in bioactive compounds from the olive fruit and leaves, may be an effective tool for reducing blood pressure and cholesterol levels alone or in combination with pharmacological anti-hypertensive treatment.

An Improved Scalable Synthesis of α- and β-Amyrin

The synthesis of α- and β-amyrin was accomplished starting from easily accessible starting materials, oleanolic, and ursolic acid. The procedures allow the preparation of β-amyrin in an exceptionally short scalable manner via selective iodation and reduction. For α-amyrin, a different synthetic approach had to be chosen providing access to α-amyrin in medium-to-large scale.

Antihypertensive effects of oleuropein-enriched olive leaf extract in spontaneously hypertensive rats

The effects of chronic consumption of oleuropein-enriched (15% w/w) olive leaf extract (OLE) on blood pressure, endothelial function, and vascular oxidative and inflammatory status in spontaneously hypertensive rats (SHR) were evaluated. Ten Wistar Kyoto rats (WKY) and twenty SHR were randomly assigned to three groups: a control WKY group, a control SHR group and a SHR group treated with OLE (30 mg kg(-1)) for 5 weeks. Long-term administration of OLE reduced systolic blood pressure, heart rate, and cardiac and renal hypertrophy. OLE treatment reversed the impaired aortic endothelium-dependent relaxation to acetylcholine observed in SHR. OLE restored aortic eNOS phosphorylation at Ser-1177 and Thr-495 and increased eNOS activity. OLE eliminated the increased aortic superoxide levels, and reduced the elevated NADPH oxidase activity, as a result of reduced NOX-1 and NOX-2 mRNA levels in SHR. OLE reduced the enhanced vascular TLR4 expression by inhibition of mitogen-activated protein kinase (MAPK) signaling with the subsequent reduction of proinflammatory cytokines. In conclusion, OLE exerts antihypertensive effects on genetic hypertension related to the improvement of vascular function as a result of reduced pro-oxidative and pro-inflammatory status.

Antihyperglycemic Activity of Eucalyptus tereticornis in Insulin-Resistant Cells and a Nutritional Model of Diabetic Mice

Eucalyptus tereticornis is a plant used in traditional medicine to control diabetes, but this effect has not been proved scientifically. Here, we demonstrated through in vitro assays that E. tereticornis extracts increase glucose uptake and inhibit their production in insulin-resistant C2C12 and HepG2 cells, respectively. Furthermore, in a nutritional model using diabetic mice, the administration of ethyl acetate extract of E. tereticornis reduced fasting glycaemia, improved tolerance to glucose, and reduced resistance to insulin. Likewise, this extract had anti-inflammatory effects in adipose tissue when compared to control diabetic mice. Via bioguided assays and sequential purification of the crude extract, a triterpenoid-rich fraction from ethyl acetate extracts was shown to be responsible for the biological activity. Similarly, we identified the main compound responsible for the antihyperglycemic activity in this extract. This study shows that triterpenes found in E. tereticornis extracts act as hypoglycemic/antidiabetic compounds and contribute to the understanding of their use in traditional medicine.

Effects of oleuropein in rats with simultaneous type 2 diabetes and renal hypertension: a study of antihypertensive mechanisms

The mechanism of oleuropein's antihypertensive effects was examined in rat model of simultaneous type 2 diabetes and renal hypertension (diabetic hypertensive). Five groups of male Sprague-Dawley rats including a control, a diabetic-hypertensive group receiving vehicle, and three diabetic-hypertensive groups receiving oleuropein at 20, 40, or 60 mg/kg/day were used. The duration of diabetes was 10 weeks; during the last 4 weeks of which, animals were hypertensive and received vehicle or oleuropein. Systolic blood pressure, glucose and malondialdehyde, heart rate, and maximal response to phenylephrine (PE) in the absence of nitro-L-arginine methyl ester (L-NAME) of oleuropein-treated groups were significantly lower than those of vehicle-treated group. Erythrocyte superoxide dismutase, maximal response to PE in the presence of L-NAME, and maximal response to acetylcholine (Ach) of oleuropein-treated groups were significantly higher than those of vehicle-treated group. The findings indicate that antihypertensive effects of oleuropein might be partly mediated by improving the release of nitric oxide, and antioxidant and sympathoplegic activities.

Microvascular disorders in obese Zucker rats are restored by a rice bran diet

BACKGROUND AND AIM

Nutritional-based approaches aimed to prevent microvascular dysfunction associated to obesity present potential advantages over pharmacological strategies. Our aim was to test whether a rice bran enzymatic extract (RBEE)-supplemented diet could attenuate microvascular alterations in obese rats.

METHODS AND RESULTS

Lean and obese Zucker rats were fed standard diet supplemented or not with 1% and 5% RBEE for 20 weeks. Functional studies were performed in small mesenteric arteries in isometric myograph. Immunoblotting and fluorescence studies were made in arterial homogenates and arterial sections, respectively. RBEE-supplementation restored microvascular function in obese rats through a marked increase in NO and endothelial-derived hyperpolarizing factor contribution by up-regulation of eNOS and calcium-activated potassium channels expression, respectively, in association to a substantial reduction of microvascular inflammation and superoxide anion formation. These data agrees with the beneficial actions of RBEE on dyslipidemia, hyperinsulinemia and hypertension in obesity.

CONCLUSION

The multi-factorial properties of RBEE-diet, especially for restoring the function of small resistance arteries shows this dietary-based approach to be a promising candidate for prevention of microvascular alterations in obesity, which are crucial in cardiovascular events in obese subjects.

Bioactive properties of the main triterpenes found in olives, virgin olive oil, and leaves of Olea europaea

Oleanolic acid, maslinic acid, uvaol, and erythrodiol are the main triterpenes present in olives, olive tree leaves, and virgin olive oil. Their concentration in virgin olive oil depends on the quality of the olive oil and the variety of the olive tree. These triterpenes are described to present different properties, such as antitumoral activity, cardioprotective activity, anti-inflammatory activity, and antioxidant protection. Olive oil triterpenes are a natural source of antioxidants that could be useful compounds for the prevention of multiple diseases related to cell oxidative damage. However, special attention has to be paid to the concentrations used, because higher concentration may lead to cytotoxic or biphasic effects. This work explores all of the bioactive properties so far described for the main triterpenes present in virgin olive oil.

Protective effect of a pomace olive oil concentrated in triterpenic acids in alterations related to hypertension in rats: mechanisms involved

SCOPE

Despite the amount of information and research on the effects of virgin olive oil and its components in cardiovascular disease, little attention has been paid to the effects of pomace olive oil, an olive oil subproduct traditionally used in Spain. The aim of the present study was to evaluate the potential effects of a pomace olive oil concentrated in triterpenic acids (POCTA) on blood pressure, cardiac hemodynamics, and functional and molecular vascular alterations associated with hypertension in spontaneously hypertensive rats (SHR).

METHODS AND RESULTS

The study showed that POCTA attenuated the increase of blood pressure in SHR. This effect was associated with an improvement in endothelium-dependent relaxation, enhancement of vascular expression of endothelial nitric oxide synthase, and reduction of tumor necrosis factor alpha, transforming growth factor beta, and collagen I. Furthermore, POCTA improved cardiac hemodynamics (left ventricular systolic pressure and left ventricular end-diastolic pressure) and decreased relative kidney and lung weights.

CONCLUSION

POCTA exerts antihypertensive effects together with vascular and hypertension target organ protection in SHR. Since interest in pomace olive oil has been low, the results of this study contribute to increasing awareness of its biological and nutritional values.

Obesity: the preventive role of the pomegranate (Punica granatum)

Obesity represents a rapidly growing threat to the health of populations in an increasing number of countries. Diet intervention has been proposed as one of the strategies for weight loss and weight maintenance. Traditionally, the pomegranate, including its roots, tree bark, fruit juice, leaves, and flowers, has been used to treat some conditions such as diarrhea, hemorrhage, acidosis, and microbial infections. Pomegranate extracts have been found to have strong anti-inflammatory, antioxidant, and even antitumor properties in vivo and in vitro. More recently, positive effects on fat reduction have been shown using the pomegranate and its extracts. Many of the beneficial effects are related to the presence of anthocyanins, tannins, and very high levels of antioxidants, including polyphenols and flavonoids. Many studies have explored the effects of the pomegranate in obesity, and various mechanisms have been proposed as to how these different extracts help in fat reduction. This article provides an overview of the work done addressing the potential benefits of the pomegranate on obesity and assesses the efficacy of intervention by means of the pomegranate and its extracts. Human studies in this field are still limited and need more attention that would help in understanding the preventive and protective roles pomegranate extracts have on obesity.

Antioxidant activity and biological evaluation of olive pomace extract

The antiradical power of the methanol extracts of olive pomace (Taggiasca cultivar) achieved by high-pressure-high-temperature reactor were investigated using ABTS•(+) and DPPH• assays. The highest antioxidant activity was quantified at 90 min of contact time and 180°C of extraction temperature (64.19 ± 0.16 µg(TE) L(-1) and 15.80 ± 0.62 µg(DPPH) µL(extract) (-1)). The extract with high-antioxidant power resulted to be effective to counteract key aspects of cellular oxidation sensitive mechanisms and inflammation associated to vascular diseases. A linear correlation (p < 0.05) between total polyphenol contents and antioxidant capacity was given by the ABTS•(+) method (R (2) = 0.9184) and DPPH assay (R (2 )= 0.7062).