Oleuropein Aglycone Research Articles

Phenolics, fatty acids, and biological potential of selected Croatian EVOOs

Nutritional value of extra virgin olive oil is associated with its complex chemical composition. The aim of this study was to determine phenolic secoiridoids in Extra virgin olive oils (EVOOs) from autochthonous Croatian cultivars (Drobnica, Krvavica, Lastovka, and Oblica) by qNMR, to determine simple phenolics by UPLC, as well as to analyze the fatty acid profile, the antioxidant activity, and the oxidative stability of selected oils. This is the first study on chemical and biological characterization of selected autochthonous olives varieties. Drobnica EVOO contained the highest amount of total phenols and major secoiridoid derivatives (oleocanthal, oleacein, oleuropein aglycon, and ligstroside aglycon) compared to other oils. The antioxidant activity of Drobnica phenolics was very high by FRAP and copper‐induced LDL oxidation assays, while the oxidative stability of Drobnica oil by Rancimat method was very long (23 h).Practical applications: This study represents the contribution to the research of chemical and biological potential of monovarietal extra virgin olive oil from Croatia. EVOOs from selected Croatian autochthonous cultivars had very high phenolic content that is related to high inhibitory rate of copper‐induced oxidation of human LDL as well as the long oxidative stability. Drobnica EVOO showed very long oxidative stability. EFSA approved health claim on olive oil polyphenols (EU, 432/2012) and selected Croatian cultivars, especially Drobnica, are of interest due to its high phenolic content and strong biological potential.

Enhancement of Bioactive Phenols and Quality Values of Olive Oil by Recycling Olive Mill Waste Water

AbstractMature ‘Chondrolia Chalkidikis’ olives were processed in an industrial olive oil mill equipped with a three‐phase decanter. Water was added to the decanter at a 1:2 water‐to‐paste ratio. Olive mill waste water (ΟΜWW) was used to replace the added water at a rate of 50 or 100%. Following the final separation, the obtained oil was used for chemical analysis and sensory evaluation. All oils had similar acidity, peroxide and Κ values. OMWW‐treated olive oils presented higher total phenolic content and higher antioxidant activity based on DPPH and oven tests, but lower chlorophyll and carotenoids content. However, there was no significant difference between the 50 and 100% replacement. The phenolic profile of the treated olive oils analyzed by quantitative 1Η NMR revealed more than twofold oleocanthal and oleacein as well as oleuropein and ligstroside aglycone contents than in the control. Sensory evaluation of treated oils also showed an enhancement of fruity, bitter and pungent attributes compared to the control.

Enzymatic tailoring of oleuropein from Olea europaea leaves and product identification by HRMS/MS spectrometry

Oleuropein, a bioactive compound found in all parts of olive tree, especially in leaves and branches, presents numerous health promoting properties that increase research and market interest the last few years. In addition, oleuropein degradation products, such as hydroxytyrosol, elenolic acid, and the aglycones also exhibit biological activities with different properties compared to the starting compound. Under this view, a commercial lipase preparation Lipolase 100L and a thermophilic β-glucosidase from Myceliophthora thermophila were used for the regioselective hydrolysis of oleuropein towards the production of the corresponding biologically active compounds. The enzymatic degradation products of oleuropein, such as hydroxytyrosol, elenolic acid and its glucoside, and oleuropein aglycones were identified by LC-HRMS/MS and NMR spectroscopy. The latter, was found as a mix of diastereomers of the monoaldehydic form of oleuropein aglycone, identified as (5S, 8R, 9S)-, (5S, 8S, 9S)- and (5S, 8R, 9R). The high substrate specificity exhibited by both lipase and β-glucosidase allows the successful tailoring of oleuropein towards the production of different biologically active compounds with significant potential in the cosmeceutical and food industry.

Biophenols and Flavor in Extra Virgin Olive Oils from San Juan Province (Argentina)

AbstractThis work studied phenolic compounds and their relationship with flavor in extra virgin olive oils from Arbequina, Changlot Real, and Coratina cultivars from San Juan province (Argentina) in the 2012 and 2013 harvests. In 2013, the harvesting was brought forward by 15–17 days. The total and individual biophenols were analyzed by HPLC–UV. A taste panel recognized by the International Olive Council (IOC) carried out the sensory analysis. Oxidative stability was measured by accelerated oxidation assays using Rancimat equipment. The oils obtained in 2013 from the three cultivars had higher biophenol contents and particularly higher contents of secoiridoids and derivatives. The positive attributes (fruitiness, bitterness, and pungency) of the oils were more harmonious in the three cultivars in 2013 by enhancing the complexity with a wide range of green descriptors. The oxidative stability indices of the oils were also higher in the three cultivars in 2013. The multiple linear regression model suggested that the aldehyde and hydroxylic form of oleuropein aglycone (3,4‐DHPEA‐EA) was the main contributor (65.5%) to bitterness, while the dialdehyde form of decarboxymethyl ligstroside aglycone (p‐HPEA‐EDA), besides reducing bitterness, was the major contributor to pungency (52.2%). Among simple phenols, o‐coumaric acid contributed to bitterness (2.3%), and tyrosol (6.3%) and tyrosyl acetate (3.3%) were related to pungency.

Antioxidant potential of extra virgin olive oils extracted from three different varieties cultivated in the Italian province of Reggio Calabria

In this study, the physicochemical properties and bioactive compounds of olive oils from cultivars “Roggianella”, “Sinopolese” and “Ottobratica”, grown in the province of Reggio Calabria (Italy) have been evaluated.Polyphenols are a large family of compounds found in fruits and vegetables, which exhibit strong antioxidant activity by scavenging different families of Reactive Oxygen Species (ROS).Dialdehydic form decarboxymethyl oleuropein aglycon, hydroxytyrosol acetate, dialdehydic form oleuropein aglycon, pinoresinol, 1-acetoxypinoresinol, tyrosol and vanillic acid were the main phenolic compounds in all samples analyzed. Pinoresinol was the most abundant compound in the lignin fraction. In all oil samples analyzed the highest antioxidant capacity was attributed to Roggianella oil (36.85% I of DPPH and 4.07% I of ABTS) compared to Ottobratica (27.37% I of DPPH and 2.52% I of ABTS) and Sinopolese (18.33% I of DPPH and 1.72% I of ABTS). The main characteristics of the Roggianella cultivar were a very high concentration of total phenols (530 mg/kg of gallic acid) and α-tocopherol (211 mg/kg).

Effects of Olive Trees Age on the Minor Components of Oueslati Virgin Olive Oils Produced from Olives Harvested at Different Ripening Degrees

AbstractPhenolics, volatiles, squalene, tocopherols, and fatty acids of virgin olive oils (VOO) from adult and young olive trees of the Oueslati variety, typically cultivated in the Center of Tunisia, were analyzed at three different harvesting periods. Significant differences in contents of saturated fatty acids (p < 0.05), squalene (p < 0.05), alpha‐tocopherol and total tocopherol (p < 0.02) and oxidized form of decarboxymethyl oleuropein aglycon (p < 0.05) were seen between VOO from adult and young trees during maturation. Moreover, the volatile profiles of VOO from adult and young trees showed significant differences in the amounts of hexanal, 1‐penten‐3‐ol (p < 0.05), (Z)‐3‐hexenal and (Z)‐2‐penten‐1‐ol (p < 0.01). Principal component analysis showed that olives from adult trees should be harvested at the cherry stage of maturation to obtain a satisfactory level of oil quality, while olives from young trees should be harvested at the black maturation stage.

Synthesis and antioxidant evaluation of lipophilic oleuropein aglycone derivatives.

Oleuropein is the most important phenolic compound present in olive cultivars, but it is scarcely present in extra virgin olive oil (EVOO) due to its high hydrophilicity and degradability. Thus, a set of oleuropein aglycone derivatives were synthesized by transacetylation under mild conditions with the aim of circumventing these drawbacks and making the active moiety in oleuropein suitable to be added to food fats. The oleuropein aglycone (closed ring form) is obtained by hydrolyzing oleuropein using Lewis acid catalysis. Then, the permeation profiles as well as the antioxidant capacity of the oleuropein aglycone derivatives were evaluated by ORAC, DPPH assays and by ROS formation using the SH-SY5Y cell line. The biological activities of the obtained compounds exhibited a dependence on their level of lipophilicity.

α-Tocopherol, β-carotene, lutein, squalene and secoiridoids in seven monocultivar Italian extra-virgin olive oils

Fatty acids and bioactive lipophilic and hydrophilic compounds (tocopherols, β-carotene, lutein, squalene, total polyphenols and secoiridoids) in monocultivar Italian extra-virgin olive oil (EVOO) samples produced from the Leccino cultivar and six other yet uncharacterised cultivars (Rustica, Carpinetana, Dritta, Gentile di Chieti and Intosso) were analysed, also taking into account the effect of the type of decanter used for the oil extraction. Significant differences among cultivars were found for α-tocopherol and squalene, but not for carotenoids. Among phenols, cultivars significantly influenced oleuropein and ligstroside aglycones contents, but not those of the dialdehydic form of decarboxymethyl elenolic acid linked neither to tyrosol nor hydroxytyrosol. As previously reported, phenol is quantitatively affected by the type of decanter used for oil extraction. Accordingly, we found that the two-phases decanter preserved in the oil 1.5 times more phenolic compounds as compared with three-phases, whereas it did not influence the amount of lipophilic compounds. Moreover, our data statistically support the finding that type of decanter affects phenols also qualitatively. In fact, the two-phases decanter preferably preserved more the hydroxytyrosol secoiridoid derivatives than the tyrosol ones. Our results from one hand characterise for the first time oils previously unreported, from the other give some new indications on the relative role of factors relevant for the achievement of biologically active extra-virgin oil, i.e. the cultivar and technological ones.

Oleuropein aglycone enhances UCP1 expression in brown adipose tissue in high-fat-diet-induced obese rats by activating β-adrenergic signaling

Oleuropein is the pungent principle of raw olives. Oleuropein aglycone (OA) is a major phenolic compound in extra virgin olive oil and the absorbed form of oleuropein. We aimed to determine the mechanism underlying the nutritional effects of oleuropein and OA on interscapular brown adipose tissue (IBAT) in rats with high-fat (HF) diet-induced obesity by examining the agonistic activity of oleuropein and OA toward the transient receptor potential ankyrin 1 (TRPA1) and vanilloid 1 (TRPV1). Four-week-old male Sprague–Dawley rats were fed an HF (palm oil 30% wt:wt) diet alone or with oleuropein (HF-O, 1 g/kg diet) for 28 days. In rats fed HF-O compared to HF, urinary noradrenaline, adrenaline and UCP1 levels in IBAT were significantly higher, whereas plasma leptin levels and the total weight of the abdominal cavity adipose tissue were significantly lower. In anaesthetized 7-week-old male Sprague–Dawley rats, the OA (3.8 mg of intravenous injection)-induced increase in plasma noradrenaline secretion was suppressed by TRPA1 or TRPV1 antagonist and by a β2- or β3-adrenoceptor antagonist. Furthermore, OA-activated rat and human TRPV1s expressed on HEK293 cells at the same level as zingerone (pungent component in ginger). OA also activated humanTRPA1, and its potency was approximately 10-fold stronger than that for TRPV1. These findings suggest that OA is the agonist of both TRPA1 and TRPV1 and that OA enhances UCP1 expression in IBAT with a concomitant decrease in the visceral fat mass of HF-diet-induced obese rats through enhanced noradrenaline secretion via β-adrenergic action following TRPA1 and TRPV1 activation.

LC-DAD/ESI-MS/MS characterization of phenolic constituents in Tunisian extra-virgin olive oils: Effect of olive leaves addition on chemical composition

The aim of the present research is to evaluate the chemical characterization of main compounds from Tunisian monocultivar extra virgin olive oil (EVOO) (‘Chemlali’, ‘Chétoui’, ‘Zalmati’ and ‘crossbreeding Chemlali by Zalmati’) extracted after the addition of different amounts (0% and 3%) of olive leaves. As expected for extra virgin olive oil, the main sterols found in all analyzed samples were β-sitosterol, ∆-5-avenasterol, campesterol and clerosterol. Stigmasterol, 24-methylene-cholesterol, cholesterol, campestanol, sitostanol, ∆-7-stigmastenol, ∆-5,24-stigmastadienol, and ∆-7-avenasterol were also found in all samples, but in lower amounts. Most of these compounds were significantly affected by the cultivars but not to be affected by added leaves at 3% to olives prior to the extraction process. The obtained results revealed that 14 phenolic compounds belonging to different phenolic types were characterized and quantified by an effective HPLC-DAD-ESI-MS/MS method. In all the studied olive oil samples, dialdehydic form of elenolic acid linked to hydroxytyrosol (3,4-DHPEA-EDA), oleuropein aglycon (3,4-DHPEA-EA), and ligstroside aglycon (p-HPEA-EA) were the most abundant compounds. In addition, EVOO from ‘Chétoui’ cultivar extracted with 3% of olive leaves presented the highest amount of individual phenolic compounds.

Selective ultrasound-enhanced enzymatic hydrolysis of oleuropein to its aglycon in olive (Olea europaea L.) leaf extracts.

Hydrolysis of oleuropein, the main phenol in olive (Olea europaea L.) leaf extracts, to oleuropein aglycon and other subsequent products in the hydrolytic pathway can be catalyzed by different enzymes. Three of the most used hydrolases were assayed to catalyze the process, and β-glucosidase from Aspergillus niger was selected. Acceleration of the enzymatic hydrolysis by ultrasound (US) was studied using a Box-Behnken design (duty cycle, amplitude, cycle time) and an oleuropein standard, and the optimum US conditions for achieving maximum yield of oleuropein aglycon were 0.5s/s duty cycle, 50% amplitude and 45s cycle. The method was applied to obtain oleuropein aglycon from commercial and laboratory extracts from olive leaves, which may have a pharmacological use as deduced by its healthy properties. The kinetics of the US-assisted enzymatic hydrolysis was monitored by analysis of the target compounds using liquid chromatography-tandem mass spectrometry.

The Polyphenol Oleuropein Aglycone Modulates the PARP1-SIRT1 Interplay: AnIn Vitro and In Vivo Study.

Poly(ADP-ribose) polymerase-1 (PARP1) activation contributes to the cascade of events initiated by amyloid-β (Aβ) peptide eventually leading to cell death in Alzheimer's disease brain. A significant accumulation of PAR polymers and increase of PARP1 expression were detected in the cortex at the early (3.5 months) and intermediate (6 months) stage of Aβ deposition in the TgCRND8 mouse model. Our previous data highlighted the beneficial effects of oleuropein aglycone (OLE), the main polyphenol found in the olive oil, against neurodegeneration both in cultured cells and in model organisms. Here we found that 8-week OLE treatment (50 mg/kg of diet) to 6-month-old TgCRND8 mice rescued to control values PARP1 activation and the levels of its product, PAR. In N2a neuroblastoma cells, PARP1 activation and PAR formation upon exposure to N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) were abolished by pretreatment for 24 h with either OLE (100μM) or PARP inhibitors. A significant reduction of the NAD+ content, compared to controls, was found in N2a cells exposed to MNNG (100μM) for 90 min; the latter was slightly attenuated by cell treatment for 24 h with PJ-34 or with OLE. In vitro and in vivo, the OLE-induced reduction of PARP1 activation was paralleled by the overexpression of Sirtuin1 (SIRT1), and, in vivo, by a decrease of NF-κB and the pro-apoptotic marker p53. In N2a cells, we also found that OLE potentiates the MNNG-induced increase of Beclin1 levels. In conclusion, our data show that OLE treatment counteracts neuronal damage through modulation of the PARP1-SIRT1 interplay.

Potential Therapeutic Effects of Oleuropein Aglycone in Alzheimer's Disease.

Alzheimer's disease (AD) is an age-associated neurodegenerative amyloid disease and is considered a social and clinical problem the last decades, particularly in the Western countries. Amyloid diseases are characterized by the deposition of typically aggregated protein/peptides in tissues that are associated with brain degeneration and progressive cognitive impairment. The amyloid plaques and neurofibrillary tangles arise as a result of self-assembly into fibrillar material of amyloid-β protein and hyperphosphorylated tau, respectively. Moreover, mounting evidence shows that oxidative and nitrosative stress plays a central role in the pathogenesis of neurodegenerative disorders such as AD. Oleuropein belongs to a specific group of polyphenols, the secoiridoids, which are abundant in Oleaceae. Oleuropein aglycone is abundant in extra virgin olive oil and it is generated as a product of a glucosidase released when olive fruits are crushed. This secoiridoid compound has radical-scavenging activity and antioxidative effects and it is considered a promising target to prevent amyloid toxicity as an inhibitor of the oligomer nucleation and growth. The neuroprotective and antioxidant effects of flavonoids have been found to strongly depend on their structure and functional groups. Oleuropein aglycone counteracts amyloid aggregation and toxicity affecting different pathways: amyloid precursor protein processing, amyloid-β peptide and tau aggregation, autophagy impairment, and neuroinflammation. In the current work, available literature on oleuropein aglycone effects as antioxidant and inhibitor of amyloid deposits in AD is reviewed. Moreover, we discuss the chemistry, food sources and bioavailability of oleuropein aglycone.

Application and comparison of high‐speed countercurrent chromatography and high‐performance liquid chromatography in semi‐preparative separation of decarboxymethyl oleuropein aglycone (3,4‐DHPEA‐EDA), a bioactive secoiridoid from extra‐virgin olive oil

This paper primarily extends research on applying and comparing high‐speed countercurrent chromatography (HSCCC) and high‐performance liquid chromatography (HPLC) in semi‐preparative isolation of decarboxymethyl oleuropein aglycone (3,4‐DHPEA‐EDA), a bioactive secoiridoid, from extra‐virgin olive oil (EVOO). An EVOO phenolic extract (EVOO‐PE) was obtained by solid‐phase extraction (SPE), and this extract was subjected to one run using the maximum loading capacity of each methodology without loss of resolution. For this sample set, the HSCCC method proved to be a more efficient approach regarding loading capacity, solvent consumption, and throughput compared with the HPLC method. However, the purity of the target from HPLC was superior to that of HSCCC, as the number of theoretical plates could not match that of HPLC. Therefore, we propose that HPLC should be used when higher purities are required, despite higher costs. In addition, HPLC is orthogonal and complementary to HSCCC, and can often provide straightforward resolution of otherwise difficult separations by HSCCC.Practical applications: Our results indicate that the optimized HSCCC is an economic process, and hence, a good candidate for further scaling‐up to preparative and industrial scales, as long as the chromatographic profile of the sample itself is simple enough to achieve good resolution, or a very high purity of the compound of interest is not required. For those cases, HPLC would provide superior target purity but would result in higher costs.This paper compares high‐speed countercurrent chromatography (HSCCC) and high‐performance liquid chromatography (HPLC) in semi‐preparative isolation of decarboxymethyl oleuropein aglycone (3,4‐DHPEA‐EDA), a bioactive secoiridoid, from extra‐virgin olive oil (EVOO). An EVOO phenolic extract (EVOO‐PE) was obtained by solid‐phase extraction (SPE), and this extract was subjected to one run using the maximum loading capacity of each methodology without loss of resolution. For this sample set, the HSCCC method proved to be a more efficient approach regarding loading capacity, solvent consumption, and throughput compared with the HPLC method. However, the purity of the target from HPLC was superior to that of HSCCC, as the number of theoretical plates could not match that of HPLC.

Antioxidant compounds of Iranian olive oils influenced by growing area, ripening stage, and cultivar

Phenolic and tocopherol compounds of virgin olive oils, obtained from three imported cultivars (cvs) of Mission, Beleydi, and Koroneiki collected in two different ripening stages from two completely different regions (subdesertic zone (Qom) and Caspian zone (Gorgan)), were determined. Regardless of the growing area conditions, Beleydi cultivars showed the lowest oil content, total phenolic content, secoiridoids, and oleuropein aglycone along with the highest content of decarboxy methyl ligstroside aglycon, ligstroside aglycone, and consequently the lower oxidative stability. Moreover, in spite of lower oil contents, the cvs growing in Qom had higher total phenolic compounds, secoiridoids, oleuropein aglycone and higher oxidative stability. Furthermore, the amount of most of the studied components decreased during the ripening stages.Practical applications: For selection of well‐characterized cvs, assessing cv‐cultivation zone‐maturity seems unavoidable before commercialization. This trend supports the differentiation of various olive oils and have motivated new and unique branding that assist their sales as well as the need for evaluating the adaptability of imported olive cvs into different growing areas and the most appropriate time of harvest before developing plantations, as a key point for mills due to the increased competitiveness and quality protection.Physicochemical properties of selected olive cultivars grown in Iran were determined and a correlation between their phenolic compounds and oxidative stability was achieved. Finally, geographic origin of olive cvs was determined by using principal component analysis.

Oleuropein aglycone and polyphenols from olive mill waste water ameliorate cognitive deficits and neuropathology

In TgCRND8 (Tg) mice we checked the dose-response effect of diet supplementation with oleuropein aglycone (OLE) at 12.5 or 0.5mgkg-1 of diet. We also studied the effects of dietary intake of the mix of polyphenols present in olive mill waste water administered at a total dose as high as the highest dose of OLE (50mgkg-1 of diet) previously investigated. Four month-old Tg mice were equally divided into four groups and treated for 8weeks with a modified low fat (5.0%) AIN-76A diet (10gday-1 per mouse) as such, supplemented with OLE (12.5 or 0.5mgkg-1 of diet) or with a mix of polyphenols (50mgkg-1 of diet) found in olive mill waste water. Behavioural performance was evaluated by the step down inhibitory avoidance and object recognition tests. Neuropathology was analyzed by immunohistochemistry. OLE supplementation at 12.5mgkg-1 of diet and the mix of polyphenols was found to improve significantly cognitive functions of Tg mice (P<0.0001). Aß42 and pE-3Aß plaque area and number were significantly reduced in the cortex by OLE and in the cortex and hippocampus by the mix of polyphenols (P<0.01, P<0.001 and P<0.0001). Similar autophagy induction was found in the brain cortex of differently treated mice. Our results extend previous data showing that the effects of OLE on behavioural performance and neuropathology are dose-dependent and not closely related to OLE by itself. In fact, diet supplementation with the same dose of a mix of polyphenols found in olive mill waste water resulted in comparable neuroprotection.

Determination of Bitterness of Extra Virgin Olive Oils by Amperometric Detection

AbstractA flow injection system with amperometric detection at potentials poised at +0.4 and +0.9 V was used to evaluate intensity of the bitter taste in monovarietal Extra Virgin Olive Oils (EVOO). Results from the proposed method were based on the extraction of the bitter constituents of the virgin olive oil samples in methanol‐water, followed by the direct amperometric measurement. These potentials were selected according to the hydrodynamic voltammogram of oleuropein, one of the most prominent and bitter phenolic compound found in EVOO. The amperometric detection was applied on 32 monovariatal EVOO samples. Results were correlated with the phenolic profile measured by high performance liquid chromatography (HPLC). The amperometric signal at +0.9 V mainly correlated with the total phenols of the samples (R2=0.81), whereas the signal at +0.4 V mainly correlated with oleuropein aglycone (3,4 DHPEA‐EDA, R2=0.79). Bitterness intensity of the samples was evaluated by a trained sensory panel of experts and the results compared to those obtained by the amperometric flow system. The best correlation with the bitter taste was achieved by the sensor at +0.4 V (R2=0.72). A calibration model based on partial least squares was built with three variables, namely the sensors set at +0.4 and +0.9 V and the total phenol content of the EVOO extracts. The model showed a moderate capacity to predict the bitterness of the EVOO samples using leave one out method, (R2=0.75) and in prediction of a test set of samples (R2=0.7). Such approach is very promising for future studies.

As oil blending affects physical, chemical, and sensory characteristics of flavoured olive oils

Extra-virgin olive oils used in the production of flavoured oils can derive from a single cultivar or can be a blend of two or more mono-varietal oils. In order to investigate the effects of the characteristics of the oil blends on the quality of the deriving flavoured oils, three mono-cultivar extra-virgin olive oils (Coratina, Peranzana, Ogliarola) were used to produce three blends, which were successively flavoured by infusion. From each blend, three types of flavoured olive oils were produced: basil, chilli pepper, and garlic + chilli pepper. Mono-varietal extra-virgin olive oils, blends, and flavoured oils were submitted for routine analyses and for determination of polar compounds, phenolic profile, antioxidant activity, and volatile profiles. The panel and consumer tests were also carried out on the flavoured oils. Along with the undoubted influence of the flavouring agents, the quality parameters of each blend changed and their changes greatly depend on the starting blend. The parameters mostly affected by oil blend were: acidity, K232, peroxide values, diacylglycerols, polar compounds, total phenolics, antioxidant activity, and phenolics such as p-coumaric acid, tyrosol acetate, vanillic acid, tyrosol, hydroxytyrosol, hydroxytyrosol acetate, dialdehydic form of elenolic acid linked to tyrosol, and ligstroside aglycone, oleuropein aglycone. The effects of oil blending were rather limited on volatile profiles and sensory characteristics.

The polyphenol Oleuropein aglycone hinders the growth of toxic transthyretin amyloid assemblies

Transthyretin (TTR) is involved in a subset of familial or sporadic amyloid diseases including senile systemic amyloidosis (SSA), familial amyloid polyneuropathy and cardiomyopathy (FAP/FAC) for which no effective therapy has been found yet. These conditions are characterized by extracellular deposits primarily found in the heart parenchyma and in peripheral nerves whose main component are amyloid fibrils, presently considered the main culprits of cell sufferance. The latter are polymeric assemblies grown from misfolded TTR, either wt or carrying one out of many identified mutations. The recent introduction in the clinical practice of synthetic TTR-stabilizing molecules that reduce protein aggregation provides the rationale to search natural effective molecules able to interfere with TTR amyloid aggregation by hindering the appearance of toxic species or by favoring the growth of harmless aggregates. Here we carried out an in depth biophysical and morphological study on the molecular features of the aggregation of wt- and L55P-TTR involved in SSA or FAP/FAC, respectively, and on the interference with fibril aggregation, stability and toxicity to cardiac HL-1 cells to demonstrate the ability of Oleuropein aglycone (OleA), the main phenolic component of the extra virgin olive oil. We describe the molecular basis of such interference and the resulting reduction of TTR amyloid aggregate cytotoxicity. Our data offer the possibility to validate and optimize the use of OleA or its molecular scaffold to rationally design promising drugs against TTR-related pathologies that could enter a clinical experimental phase.

Phenolic Compounds, Antioxidant Activity, and Other Characteristics of Extra Virgin Olive Oils from Italian Autochthonous VarietiesTonda di Villacidro,Tonda di Cagliari,Semidana, andBosana

Extra virgin olive oils (EVOOs) from the fruits of Italian autochthonous varietiesTonda di Villacidro,Tonda di Cagliari,Semidana, andBosanawere investigated to promote their quality aspects. All the analyzed EVOOs showed low values of acidity (≤0.45%) and of peroxide value (≤6.22 mEq O2/kg). There were no relevant differences in fatty acids and triacylglycerols composition among the four EVOOs. Tocopherols determined by HPLC-FL revealed thatBosanaoil was characterized by the highestα-tocopherol level (213.3 ± 55.4 mg/kg). Chlorophylls, carotenoids, and total phenol (TP) contents as well as antioxidant activity (FRAP, DPPH∙, and ABTS∙+assays) of the oils hydrophilic fractions (HFs) were assessed by spectrophotometric methods. Some differences concerning the antioxidant activity and the TP content were observed:Bosanaoil HF activity was the most pronounced (1.17 ± 0.37 mmol TEAC/kg) and it contained the highest TPs amount (335.20 ± 121.34 mg/kg). HFs phenolic composition was determined by HPLC-DAD. The main identified phenols were secoiridoids, dominating inBosanaoil, such as decarboxymethyl ligstroside aglycone (p-HPEA-EDA, 35.8 ± 19.9 mg/kg) and oleuropein aglycone (3,4-HPEA-EA up to 84.7 mg/kg). In summary, all the four varieties showed good characteristics for the use as quality EVOO.