Oleuropein, the bitter principle of olives, enhances nitric oxide production by mouse macrophages

Effects of hydroxytyrosol-20 on carrageenan-induced acute inflammation and hyperalgesia in rats

Hydroxytyrosol (HT) is a simple phenol compound extracted from olive leaves. The content of HT in the studied preparation was about 20%, and the preparation was called hydroxytyrosol-20 (HT-20). HT has antioxidant and antiinflammatory activities. There has been no report so far on the efficacy of HT-20 in carrageenan-induced acute inflammation and hyperalgesia in rats. Therefore, the aim of this study was to assess the inhibitory role of HT-20 on carrageenan-induced swelling and hyperalgesia of rat paw. Paw inflammation was assessed by the increase in paw volume and hyperalgesia. The rat paws were cut out under ether anesthesia at 270 min after administration of carrageenan. The tissue of the right paw was isolated separately from the individual rat. The levels of the tumor necrosis factor-alpha (TNF-alpha), interleukin 1beta (IL-1beta) and interleukin 10 (IL-10) mRNA in the tissue were estimated by reverse transcription-polymerase chain reaction (RT-PCR). The results showed that the paw pressure thresholds of rats orally administered HT-20 significantly increased at 210, 240 and 270 min after administration of carrageenan, compared with corresponding basal paw pressure thresholds; the degree of swelling of the right hind paw showed a statistically significant reduction, compared with rats in the carrageenan-treated control. In this model, HT-20 appears to decrease pro-inflammatory cytokines IL-1beta and TNF-alpha and not to increase the antiinflammatory cytokine mRNA expression of IL-10.

Food supplementation with an olive (Olea europaea L.) leaf extract reduces blood pressure in borderline hypertensive monozygotic twins

Hypertension is a harmful disease factor that develops unnoticed over time. The treatment of hypertension is aimed at an early diagnosis followed by adequate lifestyle changes rather than pharmacological treatment. The olive leaf extract EFLA943, having antihypertensive actions in rats, was tested as a food supplement in an open study including 40 borderline hypertensive monozygotic twins. Twins of each pair were assigned to different groups receiving 500 or 1000 mg/day EFLA943 for 8 weeks, or advice on a favourable lifestyle. Body weight, heart rate, blood pressure, glucose and lipids were measured fortnightly. Blood pressure changed significantly within pairs, depending on the dose, with mean systolic differences of < or =6 mmHg (500 mg vs control) and < or =13 mmHg (1000 vs 500 mg), and diastolic differences of < or =5 mmHg. After 8 weeks, mean blood pressure remained unchanged from baseline in controls (systolic/diastolic: 133 +/- 5/77 +/- 6 vs 135 +/- 11/80 +/- 7 mmHg) and the low-dose group (136 +/- 7/77 +/- 7 vs 133 +/- 10/76 +/- 7), but had significantly decreased for the high dose group (137 +/- 10/80 +/- 10 vs 126 +/- 9/76 +/- 6). Cholesterol levels decreased for all treatments with significant dose-dependent within-pair differences for LDL-cholesterol. None of the other parameters showed significant changes or consistent trends. Concluding, the study confirmed the antihypertensive and cholesterol-lowering action of EFLA943 in humans.

Virgin olive oil polyphenol hydroxytyrosol acetate inhibits in vitro platelet aggregation in human whole blood: comparison with hydroxytyrosol and acetylsalicylic acid

Hydroxytyrosol acetate (HT-AC) is a polyphenol present in virgin olive oil (VOO) at a proportion similar to hydroxytyrosol (HT) (160-479 micromol/kg oil). The present study was designed to measure the in vitro platelet antiaggregating activity of HT-AC in human whole blood, and compare this effect with that of HT and acetylsalicylic acid (ASA). The experiments were designed according to the standard procedure to investigate the activity of ASA. HT-AC and HT inhibited platelet aggregation induced by ADP, collagen or arachidonic acid in both whole blood and platelet-rich plasma (PRP). ASA and HT-AC had a greater effect in whole blood than in PRP when ADP or collagen was used as inducer. ASA and HT-AC had a greater effect in PRP+leucocytes than in PRP alone. All three compounds inhibited platelet thromboxane B2 and leucocyte 6-keto-prostaglandin F1alpha (6-keto-PF1 alpha) production. The thromboxane/6-keto-PGF1alpha inhibition ratio (as an indirect index of the prostanoid equilibrium) was 10.8 (SE 1) for HT-AC, 1.0 (SE 0.1) for HT and 3.3 (SE 0.2) for ASA. All three compounds stimulated nitric oxide production, although HT was a weaker effect. In our experiments only concentrations higher than 500 microm (HT) or 1 mm (HT-AC and ASA) inhibited 3-nitrotyrosine production. All three compounds inhibited the production of TNFalpha by leucocytes, with no significant differences between them. In quantitative terms HT-AC showed a greater antiplatelet aggregating activity than HT and a similar activity to that of ASA. This effect involved a decrease in platelet thromboxane synthesis and an increase in leucocyte nitric oxide production.

Localization of the noncovalent binding site between amyloid-beta-peptide and oleuropein using electrospray ionization FT-ICR mass spectrometry

Abnormal accumulation and aggregation of amyloid-beta-peptide (Abeta) eventually lead to the formation and cerebral deposition of amyloid plaques, the major pathological hallmark in Alzheimer's disease (AD). Oleuropein (OE), an Olea europaea L. derived polyphenol, exhibits a broad range of pharmacological properties, such as antioxidant, anti-inflammatory, and antiatherogenic, which could serve as combative mechanisms against several reported pathways involved in the pathophysiology of AD. The reported noncovalent interaction between Abeta and OE could imply a potential antiamyloidogenic role of the latter on the former via stabilization of its structure and prevention of the adaptation of a toxic beta-sheet conformation. The established beta-sheet conformation of the Abeta hydrophobic carboxy-terminal region and the dependence of its toxicity and aggregational propensity on its secondary structure make the determination of the binding site between Abeta and OE highly important for assessing the role of the interaction. In this study, two different proteolytic digestion protocols, in conjunction with high-sensitivity electrospray ionization mass spectrometric analysis of the resulting peptide fragments, were used to determine the noncovalent binding site of OE on Abeta and revealed the critical regions for the interaction.

Beneficial effects of vegetable oils (corn, olive and sunflower oils) and alpha-tocopherol on anti-inflammatory and gastrointestinal profiles of indomethacin in rats

Nonsteroidal anti-inflammatory drugs (NSAIDs) such as indomethacin are widely used in the treatment of inflammation, fever and pain. However, NSAIDs cause gastric damage as a major adverse reaction. In this study, the effects of vegetable oils (corn, olive and sunflower oils) and alpha-tocopherol on anti-inflammatory and gastrointestinal profiles of indomethacin were evaluated in rats. Results showed that indomethacin given with sunflower, corn and olive oils reduced paw edema induced by carrageenan by 79.5%, 74.0% and 60.5%, whereas individual indomethacin and diclofenac reduced paw edema by 56.2% and 50.7%, respectively. Furthermore, it has been found that the vegetable oils possess significant anti-inflammatory effect against paw edema when given alone. These results showed that the vegetable oils have beneficial effects on reduction paw edema induced by carrageenan. Besides, the administration of indomethacin together with the vegetable oils and alpha-tocopherol did not cause a statistically significant gastric damage in rats (P>0.05). However, indomethacin caused statistically significant gastric lesions as compared with untreated rats (P<0.05). Moreover, it was also found that the effects of the vegetable oils and alpha-tocopherol improved the levels of antioxidant defense systems in rat stomach tissues against oxidative damage. These results suggest that indomethacin as well as other NSAIDs do not have any adverse effect on the gastrointestinal tract when they are used together with vegetable oils and vitamin E or as the preparations of the oils.

Inhibition of platelet aggregation by olive oil phenols via cAMP-phosphodiesterase

The aim of the present study was to confirm that olive oil phenols reduce human platelet aggregability and to verify the hypothesis that cAMP- and cGMP- phosphodiesterases (PDE) could be one of the targets of the biological effect. Four extracts from oils characterized by a high phenol content (HPE), and low phenol levels (LPE) were prepared and analyzed quali- and quantitatively by HPLC-UV and electrospray ionization–MS/MS. Human washed platelets stimulated with thrombin were used for the aggregation assay. Human platelet cAMP-PDE and recombinant PDE5A1 were used as enzyme source. Platelet aggregation and enzyme activity were assayed in the presence of HPE, LPE and individual phenols. The phenol content of HPE ranged between 250 and 500 mg/kg, whereas the LPE content was 46 mg/kg. The compounds identified were hydroxytyrosol (HT), tyrosol (TY), oleuropein aglycone (OleA) and the flavonoids quercetin (QU), luteolin (LU) and apigenin (AP). OleA was the most abundant phenol (range 23·3 to 37·7 %) and LU was the most abundant flavonoid in the extracts. Oil extracts inhibited platelet aggregation with an 50% inhibitory concentration interval of 1·23–11·2 μg/ml. The inhibitory effect of individual compounds (10 μm) including homovanillyl alcohol (HVA) followed this order: OleA>LU>HT = TY = QU = HVA, while AP was inactive. All the extracts inhibited cAMP-PDE, while no significant inhibition of PDE5A1 (50μg/ml) was observed. All the flavonoids and OleA inhibited cAMP-PDE, whereas HT, TY, HVA (100 μm) were inactive. Olive oil extracts and part of its phenolic constituents inhibit platelet aggregation; cAMP-PDE inhibition is one mechanism through which olive oil phenols inhibit platelet aggregation.

The effects of polyphenols in olive leaves on platelet function

INTRODUCTION

The phenolic compounds of olive leaves and olive oils in the Mediterranean diet have been associated with a reduced incidence of heart disease. Accordingly, antioxidant-rich diets may prevent the deleterious effects of oxidative metabolism by scavenging free radicals, thus inhibiting oxidation and delaying atherosclerosis. The process involves phospholipase C activation and arachidonic acid metabolism, and is thought to reduce hydrogen peroxide (H(2)O(2)). In our study, an extract of Olea europaea L. leaves was used. The active phenolic compounds in this extract are part of the secoiridoid family, known for their capacity to scavenge H(2)O(2). The results from this study will help to improve our understanding of effects of polyphenol antioxidants in olive leaf extract on platelet function.

METHODS

Full blood examination (FBE), platelet aggregation, and ATP release were performed on samples from fasting, normal, healthy male subjects. Platelet function at increasing concentrations of oleuropein was investigated through measures of platelet aggregation and ATP release from activated platelets.

RESULTS

Blood analysis (n=11) revealed a significant dose-dependant reduction in platelet activity with olive extract concentrations of 1.0% v/v (P<0.001). ATP Release showed a similar pattern (P=0.02).

CONCLUSIONS

Olive leaf polyphenols derived from O. europaea L. leaves inhibited in vitro platelet activation in healthy, non-smoking males. Further bioavailability studies need to be undertaken to determine the in vivo effect of extract on platelet function and to validate the present results.

Retention and distribution of polyphenols after pan-frying of French fries in oils enriched with olive leaf extract

Palm oil, olive oil, and sunflower oil were supplemented with an extract rich in polyphenols obtained from olive tree (Olea europaea) leaves at levels of 120 and 240 mg total polyphenols per kilogram of oil. Pan-frying of potatoes was performed in both the enriched and the nonsupplemented oils under domestic frying conditions. Total polyphenol content was estimated by the Folin-Ciocalteau assay, oleuropein was determined by HPLC analysis, while other individual polyphenols by GC/MS analysis. Fourteen polyphenol species were identified in the olive leaf extract, among which oleuropein predominated (1.25 g/kg olive leaves). All the enriched oils contained oleuropein before and after frying. Oleuropein as well as other polyphenol species were detected in all French fries cooked in enriched oils. Polyphenol intake by consuming French fries pan-fried in the enriched oils was calculated to be 6 to 31 times higher than that in the case of French fries fried in commercial oils, being dependent on the frying oil type.

Black Lucques olives prevented bone loss caused by ovariectomy and talc granulomatosis in rats

This study was conducted to determine whether olive fruits, rich in micronutrients, might improve bone loss in ovariectomized (OVX) rats (an experimental model of postmenopausal osteoporosis) and in OVX rats with granulomatosis inflammation (a model of senile osteoporosis). Six-month-old Wistar female rats underwent ovariectomy and were then immediately treated orally by substituting oil in the diet by 10 g/d green Lucques olives or 6 g/d black Lucques olives for each rat for 84 days. OVX rats and sham-operated controls received the same diet with oil. Three weeks before the end of the experiment, subcutaneous inflammation was provoked by injections of sterile magnesium silicate in half the animals in each group. In OVX rats, granulomatosis inflammation, characterized by a rise in inflammatory parameters such as fibrinogen, alpha1-acid glycoprotein, spleen weight and granulocyte level, and an impairment of oxidative status (as shown by a decrease in plasma antioxidant capacity, a higher rate of isoprostane excretion) elicited a bone loss in the whole femur and in the metaphyseal areas considered on their own. Whereas green olives had no effect on osteopenia, consumption of the black variety prevented bone loss in the whole femur and at cortical sites in those oestrogen-deficient animals with talc inflammation (diaphyseal bone mineral density: black olives and inflammation 0-2323 (SE 0.0026) v. ovariectomy and inflammation 0.2117 (SE 0.0030); P=0.027). This bone-sparing effect seemed to result from an improvement in the inflammatory and oxidative status. The present data show that black olives are able to prevent bone loss in an experimental model of senile osteoporosis (oestrogen-deficient rats in which a low-grade inflammation was induced by talc injection).

Encapsulation of olive leaf extract in beta-cyclodextrin

Olive leaf extract, rich in oleuropein, formed an inclusion complex with beta-cyclodextrin (beta-CD) upon mixing of the components in aqueous media and subsequent freeze-drying. Inclusion complex formation was confirmed by differential scanning calorimetry (DSC). DSC thermograms indicated that the endothermic peaks of both the olive leaf extract and the physical mixture of olive leaf extract with beta-CD, attributed to the melting of crystals of the extract, were absent in DSC thermogram of inclusion complex. Moreover, DSC studies under oxidative conditions indicated that the complex of olive leaf extract with beta-CD was protected against oxidation, since it remained intact at temperatures where the free olive leaf extract was oxidized. Phase solubility studies afforded A L type diagrams, 1:1 complex stoichiometry, a moderate binding constant ( approximately 300 M (-1)), and an increase of the aqueous solubility by approximately 50%. The formation of the inclusion complex was also confirmed by nuclear magnetic resonance (NMR) studies of beta-CD solutions in the presence of both pure oleuropein and olive leaf extract. The NMR data have established the formation of a 1:1 complex with beta-CD that involves deep insertion of the dihydroxyphenethyl moiety inside the cavity from its secondary side.

Vasculoprotective potential of olive oil components

Epidemiological and clinical studies found that the traditional Mediterranean-style diet is associated with significantly lower mortality from coronary artery disease. Although it is difficult to isolate individual dietary factors, cumulative evidence suggests that olive oil, used as primary source of fat by Mediterranean populations, may play a key role in the observed cardiovascular benefit. Olive oil is a priceless source of vitamins and polyphenolic antioxidants, and has a balanced ratio of monounsaturated and polyunsaturated fatty acids. There are multiple mechanisms by which olive oil might impact the development of atherosclerosis. Olive oil decreases LDL-cholesterol and increases HDL-cholesterol, and also reduces oxidative stress due to polyphenols, which are able to scavenge free radicals and protect LDL from oxidation. In addition, olive oil components may interfere with the inflammatory response within atherosclerotic lesion, by inhibiting endothelial activation involved in monocyte recruitment during early atherogenesis and macrophage production of inflammatory cytokines and matrix degrading enzymes, thus improving vascular stability. Other vasculoprotective mechanisms by olive oil components derive from anti-thrombotic and anti-hypertensive actions. The available data support the need to preserve certain dietary traditions, such as olive oil consumption, to counteract the burden of cardiovascular disease.

Bioavailability of the phenolic compounds of the fruits (drupes) of Olea europaea (olives): impact on plasma antioxidant status in humans

To examine the bioavailability of olive polyphenols and to correlate it with their antioxidant efficacy, plasma and urine from healthy volunteers who had consumed 20 olives were subjected to (a) GC-MS analysis for individual phenolics, (b) estimation of plasma total polyphenol content and (c) estimation of plasma total antioxidant potential. Olive polyphenols were absorbed and metabolized within the body, occurring in plasma mainly in the conjugated form with glucuronic acid and reaching C(max) in 1-2h. Excretion rates were maximum at 0-4h. Tyrosol and hydroxytyrosol increased in plasma after intervention. Total antioxidant potential increased (p<0.05). The results indicate that olive polyphenols possess good bioavailability, which is in accordance with their antioxidant efficacy.

The olive constituent oleuropein exhibits proteasome stimulatory properties in vitro and confers life span extension of human embryonic fibroblasts

Normal human fibroblasts undergo replicative senescence due to both genetic and environmental factors. Senescence and aging can be further accelerated by exposure of cells to a variety of oxidative agents that contribute among other effects to the accumulation of damaged proteins. The proteasome, a multicatalytic nonlysosomal protease, has impaired function during aging, while its increased expression delays senescence in human fibroblasts. The aim of this study was to identify natural compounds that enhance proteasome activity and exhibit antiaging properties. We demonstrate that oleuropein, the major constituent of Olea europea leaf extract, olive oil and olives, enhances the proteasome activities in vitro stronger than other known chemical activators, possibly through conformational changes of the proteasome. Moreover, continuous treatment of early passage human embryonic fibroblasts with oleuropein decreases the intracellular levels of reactive oxygen species (ROS), reduces the amount of oxidized proteins through increased proteasome-mediated degradation rates and retains proteasome function during replicative senescence. Importantly, oleuropein-treated cultures exhibit a delay in the appearance of senescence morphology and their life span is extended by approximately 15%. In summary, these data demonstrate the beneficial effect of oleuropein on human fibroblasts undergoing replicative senescence and provide new insights towards enhancement of cellular antioxidant mechanisms by natural compounds that can be easily up-taken through normal diet.

Mild photochemical synthesis of the antioxidant hydroxytyrosol via conversion of tyrosol

Hydroxytyrosol, a naturally occurred orthodiphenolic antioxidant molecule found in olive oil and olive mill wastewaters, was obtained from the wet hydrogen peroxide photocatalytic oxidation of its monophenolic precursor tyrosol. The liquid-phase oxidation of tyrosol to hydroxytyrosol was performed by use of an iron-containing heterogeneous catalyst (Al-Fe)PILC with the assistance of UV irradiation at 254 nm and at room temperature. The spectroscopic and HPLC data of the synthesized compound proved to coincide fully with those of a pure sample obtained by continuous countercurrent extraction. This reaction was found to be light-induced. The hydroxytyrosol synthesis reaction reached its maximum yield of 64.36% under the optimized operating conditions of 3.6 mM tyrosol, 0.5 g L(-1) catalyst, and 10(-2) M H2O2 with the assistance of UV light. Increasing the initial hydrogen peroxide concentration more than 10(-2) M has a diminishing return on the reaction efficiency. Catalyst can be recuperated by means of filtration and then reused in a next run after regeneration since its activity did not significantly decrease (<10%). The reaction synthesis is operationally simple and could find application for industrial purposes.

Elements of Mediterranean diet improve oxidative status in blood of kidney graft recipients

Patients were fully informed as to the study objectives and benefits, and provided written consent prior to enrolment. The study protocol was approved by the Committee on Human Research at the Pomeranian Medical University, Szczecin, Poland. An intensification of free-radical reactions may contribute to accelerated atherosclerosis in kidney graft recipients. We examined the effect of a Mediterranean-type diet (MD) on the oxidative status of the plasma and erythrocytes of kidney graft recipients. Two patient groups were formed: a study group consuming the MD diet and a control group with a low-fat diet. C-reactive protein levels in plasma, oleic acid C18: 1n-9 and linoleic acid C18: 2n-6 concentrations in triacyloglycerols were determined. To determine the oxidative status, we measured the concentrations of α-tocopherol in plasma, the content of thiobarbituric acid-reactive species (TBARS) in plasma and erythrocytes, and the activities of superoxide dismutase, catalase and glutathione peroxidase in erythrocytes. In the MD group, the activities of erythrocyte enzymes changed significantly: those of superoxide dismutase increased (P<0.001 after 6 months), catalase decreased (P<0.001 after 6 months) and glutathione peroxidase decreased (P<0.05 after 2 months). The oleic acid content of triacylglycerols was increased (P<0.006) whereas that of linoleic acid was decreased (P<0.00005), α-tocopherol levels remaining unchanged. TBARS in plasma were decreased after 6 months of MD (P<0.05). No significant correlations were observed between TBARS, oleic acid, linoleic acid and α-tocopherol levels in plasma. MD appears to protect the erythrocytes against the action of free radicals, as reflected in the modified activities of some enzymes regulating the oxidative status of these blood cells.

Oleuropein, a non-toxic olive iridoid, is an anti-tumor agent and cytoskeleton disruptor

Oleuropein, a non-toxic secoiridoid derived from the olive tree, is a powerful antioxidant and anti-angiogenic agent. Here, we show it to be a potent anti-cancer compound, directly disrupting actin filaments in cells and in a cell-free assay. Oleuropein inhibited the proliferation and migration of advanced-grade tumor cell lines in a dose-responsive manner. In a novel tube-disruption assay, Oleuropein irreversibly rounded cancer cells, preventing their replication, motility, and invasiveness; these effects were reversible in normal cells. When administered orally to mice that developed spontaneous tumors, Oleuropein completely regressed tumors in 9-12 days. When tumors were resected prior to complete regression, they lacked cohesiveness and had a crumbly consistency. No viable cells could be recovered from these tumors. These observations elevate Oleuropein from a non-toxic antioxidant into a potent anti-tumor agent with direct effects against tumor cells. Our data may also explain the cancer-protective effects of the olive-rich Mediterranean diet.

Minor components of olive oil modulate proatherogenic adhesion molecules involved in endothelial activation

The Mediterranean diet reduces the risk of coronary artery disease as a consequence of its high content of antioxidants, namely, hydroxytyrosol (HT) and oleuropein aglycone (OleA), typical of virgin olive oil. Because intercellular and vascular cell adhesion molecules (ICAM-1 and VCAM-1) and E-selectin are crucial for endothelial activation, the role of the phenolic extract from extra virgin olive oil (OPE), OleA, HT, and homovanillyl alcohol (HVA) on cell surface and mRNA expression in human umbilical vascular endothelial cells (HUVEC) was evaluated. OPE strongly reduced cell surface expression of ICAM-1 and VCAM-1 at concentrations physiologically relevant (IC50 < 1 microM), linked to a reduction in mRNA levels. OleA and HT were the main components responsible for these effects. HVA inhibited cell surface expression of all the adhesion molecules, whereas the effect on mRNA expression was weaker. These results supply new insights on the protective role of olive oil against vascular risk through the down-regulation of adhesion molecules involved in early atherogenesis.

Noncovalent interaction between amyloid-beta-peptide (1-40) and oleuropein studied by electrospray ionization mass spectrometry

Beta amyloid peptide (Abeta) is the major proteinaceous component of senile plaques formed in Alzheimer's disease (AD) brain. The aggregation of Abeta is associated with neurodegeneration, loss of cognitive ability, and premature death. It has been suggested that oxidative stress and generation of free radical species have implications in the fibrillation of Abeta and its subsequent neurotoxicity. For this reason, it is proposed that antioxidants may offer a protective or therapeutic alternative against amyloidosis. This study is the first report of the formation of the noncovalent complex between Abeta or its oxidized form and the natural derived antioxidant oleuropein (OE) by electrospray ionization mass spectrometry (ESI MS). ESI MS allowed the real time monitoring of the complex formation between Abeta, OE, and variants thereof. Several experimental conditions, such as elevated orifice potential, low pH values, presence of organic modifier, and ligand concentration were examined, to assess the specificity and the stability of the formed noncovalent complexes.

Antagonism between olive oil phenolics and nitric oxide on lymphomonocyte cytosolic calcium

Some biological actions of olive oil phenolics (inhibition of platelet aggregation, decrease of LDL-oxidation, inhibition of bacterial growth and hypertensive action) have been attributed to NOS stimulation in endothelial cells through an increase of cytosolic calcium, notwithstanding the scavenging activity of phenolics on NO and superoxide. In this paper, we determine the concentration of cytosolic calcium in human lymphomonocytes incubated with high concentrations of NO-donors (CysNO) and we evaluate the effects of olive oil phenolics on this parameter. CysNO induces a marked decrease of cytosolic calcium; both olive oil phenolics oppose this action of CysNO. The effects of phenolics and CysNO are independent and additive.

Hypoglycemic and antioxidant effect of oleuropein in alloxan-diabetic rabbits

Patients with diabetes mellitus are likely to develop certain complication such as retinopathy, nephropathy and neuropathy as a result of oxidative stress and overwhelming free radicals. Treatment of diabetic patients with antioxidant may be of advantage in attenuating these complications. Oleuropein, the active constituent of olive leaf (Olea europaea), has been endowed with many beneficial and health promoting properties mostly linked to its antioxidant activity. This study aimed to evaluate the significance of supplementation of oleuropein in reducing oxidative stress and hyperglycemia in alloxan-induced diabetic rabbits. After induction of diabetes, a significant rise in plasma and erythrocyte malondialdehyde (MDA) and blood glucose as well as alteration in enzymatic and non-enzymatic antioxidants was observed in all diabetic animals. During 16 weeks of treatment of diabetic rabbits with 20 mg/kg body weight of oleuropein the levels of MDA along with blood glucose and most of the enzymatic and non-enzymatic antioxidants were significantly restored to establish values that were not different from normal control rabbits. Untreated diabetic rabbits on the other hand demonstrated persistent alterations in the oxidative stress marker MDA, blood glucose and the antioxidant parameters. These results demonstrate that oleuropein may be of advantage in inhibiting hyperglycemia and oxidative stress induced by diabetes and suggest that administration of oleuropein may be helpful in the prevention of diabetic complications associated with oxidative stress.

Mixture of honey, beeswax and olive oil inhibits growth of Staphylococcus aureus and Candida albicans

BACKGROUND

Honey, beeswax and olive oil mixture (1:1:1, v/v) is useful in the treatment of diaper dermatitis, psoriasis and eczema. The study was designed to investigate effects of honey, olive oil, and beeswax and the mixture on growth of Staphylococcus aureus and Candida albicans isolated from human specimens.

METHODS

The following experiments were performed: 1) honey mixture was poured on holes made on plates seeded with S. aureus or C. albicans, 2) the microorganisms were cultured onto media made of honey mixture alone, nutrient agar-honey mixture and Sabouraud glucose agar-honey mixture. The concentration of honey mixture in nutrient agar or Sabouraud glucose agar was 12.5, 25, 33, 50 and 66% (v/v), and 3) honey, olive oil or beeswax was added onto nutrient agar or Sabouraud glucose agar at a ratio of 1:2 (v/v) and then were seeded with S. aureus or C. albicans.

RESULTS

Clear zone of inhibition was observed around holes filled with honey mixture; 3.5 mm on media seeded with C. albicans and 4 mm on media seeded with S. aureus. No growth of either microorganism was obtained on media made of honey mixture alone. The minimum concentration of honey mixture in nutrient agar-honey mixture media required to inhibit S. aureus was 50% and 66% concentration was required to inhibit C. albicans growth onto Sabouraud glucose agar-honey mixture media. No growth of S. aureus or C. albicans was obtained on media containing honey whereas mild to moderate growth was obtained on media containing olive oil or beeswax.

CONCLUSIONS

Honey and honey mixture apparently could inhibit growth of S. aureus or C. albicans.

Development of a sensitive and specific solid phase extraction--gas chromatography-tandem mass spectrometry method for the determination of elenolic acid, hydroxytyrosol, and tyrosol in rat urine

A novel gas chromatography-tandem mass spectrometry (GC-MS/MS) method was developed, using an ion trap mass spectrometer, for the simultaneous determination of olive oil bioactive components, elenolic acid, hydroxytyrosol, and tyrosol, in rat urine. Samples were analyzed by GC-MS/MS prior to and after enzymatic treatment. A solid phase extraction sample pretreatment step with greater than 80% analytical recoveries for all compounds was performed followed by a derivatization reaction prior to GC-MS/MS analysis. The calibration curves were linear for all compounds studied for a dynamic range between 1 and 500 ng. The limit of detection was in the mid picogram level for tyrosol and elenolic acid (300 pg) and in the low picogram level for hydroxytyrosol (2.5 pg). The method was applied to the analysis of rat urine samples after sustained oral intake of oleuropein or extra virgin olive oil as a diet supplement.

Differential anti-inflammatory effects of phenolic compounds from extra virgin olive oil identified in human whole blood cultures

OBJECTIVE

The olive oil-rich Mediterranean diet protects against cardiovascular disease, which involves inflammatory processes. This study investigated the effects of phenolic compounds found in extra virgin olive oil on inflammatory mediator production by human mononuclear cells.

METHODS

Diluted human blood cultures were stimulated with lipopolysaccharide in the presence of phenolics (vanillic, p-coumaric, syringic, homovanillic and caffeic acids, kaempferol, oleuropein glycoside, and tyrosol) at concentrations of 10(-7) to 10(-4) M. Concentrations of the inflammatory cytokines tumor necrosis factor-alpha, interleukin-1beta, and interleukin-6 and of the inflammatory eicosanoid prostaglandin E2 were measured by enzyme-linked immunosorbent assay.

RESULTS

Oleuropein glycoside and caffeic acid decreased the concentration of interleukin-1beta. At a concentration of 10(-4) M, oleuropein glycoside inhibited interleukin-1beta production by 80%, whereas caffeic acid inhibited production by 40%. Kaempferol decreased the concentration of prostaglandin E2. At a concentration of 10(-4) M, kaempferol inhibited prostaglandin E2 production by 95%. No effects were seen on concentrations of interleukin-6 or tumor necrosis factor-alpha and there were no effects of the other phenolic compounds.

CONCLUSIONS

Some, but not all, phenolic compounds derived from extra virgin olive oil decrease inflammatory mediator production by human whole blood cultures. This may contribute to the antiatherogenic properties ascribed to extra virgin olive oil.

Bioactivity and analysis of biophenols recovered from olive mill waste

Biophenols have attracted increasing attention during the past few years due to their biological activities and natural abundance and are potential targets for the food and pharmaceutical industries. Olive mill waste (OMW) is rich in biophenols and typically contains 98% of the total phenols in the olive fruit, making value addition to OMW an attractive enterprise. The phenolic profile of OMW is complex, yet this complexity has not been fully exploited in the valorization of the waste. Most work on the bioactivity of OMW has focused on antioxidant and antimicrobial activities. The analytical techniques used to identify and quantify active biophenols are also reviewed.

Clinical and mycological benefits of topical application of honey, olive oil and beeswax in diaper dermatitis

Twelve infants suffering from diaper dermatitis were treated four times daily for 7 days with a mixture containing honey, olive oil and beeswax. The severity of erythema was evaluated on a five-point scale. Three infants had severe erythema and ulceration, four had moderate erythema, and five had moderate erythema with maceration. The initial mean lesion score of 2.91 +/- 0.79 declined significantly (p < 0.05) to 2.0 +/- 0.98 (day 3), 1.25 +/- 0.96 (day 5) and 0.66 +/- 0.98 (day 7). Candida albicans was isolated initially from four patients, but from only two patients after treatment. This topical treatment was safe and well-tolerated, and demonstrated clinical and mycological benefits in the treatment of diaper dermatitis.

Activity of olive oil phenols on lymphomonocyte cytosolic calcium

Phenols, present in the Mediterranean diet, have antioxidant properties and are free radical scavengers; however, the molecular mechanisms of their beneficial effects are not yet fully understood. The level of cytosolic calcium ([Ca2+]i) is an important signal also in nonexcitable cells, including immune cells, and regulates fundamental processes. In this paper, we determine [Ca2+]i in human lymphomonocytes incubated with two olive oil phenols: 3,4-(dihydroxyphenyl)ethanol and p-(hydroxyphenyl)ethanol. Both tested phenols increase [Ca2+]i in a dose-dependent way. This effect is antagonized by nifedipine and is noticeable both in the presence and in the absence of calcium in the extracellular medium.

Genotoxicity of vegetable cooking oils in the Drosophila wing spot test

Seven vegetable oils consumed by humans were tested for genotoxic activity in the Drosophila somatic mutation and recombination test. The oils included five seed oils (sesame, sunflower, wheat germ, flax, and soy oil) and both first-class extra-virgin and low-grade (refined) olive oil. Larvae of the standard (STD) and highly bioactive (NORR) crosses of Drosophila melanogaster were fed medium containing 6% and 12% of each of the oils. Flax oil produced the strongest response, while sesame, wheat germ, and soy oil showed some genotoxic activity. Sunflower and the low-grade olive oil gave inconclusive results, and extra-virgin olive oil was clearly nongenotoxic. It is argued that the genotoxicity is probably due to the fatty acid composition of the oils, which after peroxidation can form specific DNA-adducts.

An alternative treatment for pityriasis versicolor, tinea cruris, tinea corporis and tinea faciei with topical application of honey, olive oil and beeswax mixture: an open pilot study

OBJECTIVE

To evaluate the possible role of honey, olive oil and beeswax in the treatment of skin fungal infections.

PATIENTS AND METHODS

Thirty-seven patients with pityriasis versicolor, tinea cruris, tinea corporis and tinea faciei were studied. After clinical evaluation of redness, scaling, pruritus and burning/pain sensation and mycological assessment, honey mixture containing honey, olive oil and beeswax (1:1:1) was applied to the lesions three times daily for a maximum of 4 weeks.

RESULTS

Clinical response was obtained in 86% of patients with pityriasis versicolor, 78% of patients with tinea cruris and in 75% of patients with tinea corporis. Mycological cure was obtained in 75, 71 and 62% of patients with PV, tinea cruris and tinea corporis, respectively. The patient with tinea faciei showed clinical and mycological cure 3 weeks after commencement of therapy.

CONCLUSION

Honey mixture may have place in the management of these skin conditions and rigorous, controlled trials are justified.

Antiproliferative and apoptotic effects of selective phenolic acids on T47D human breast cancer cells: potential mechanisms of action

INTRODUCTION

The oncoprotective role of food-derived polyphenol antioxidants has been described but the implicated mechanisms are not yet clear. In addition to polyphenols, phenolic acids, found at high concentrations in a number of plants, possess antioxidant action. The main phenolic acids found in foods are derivatives of 4-hydroxybenzoic acid and 4-hydroxycinnamic acid.

METHODS

This work concentrates on the antiproliferative action of caffeic acid, syringic acid, sinapic acid, protocatechuic acid, ferulic acid and 3,4-dihydroxy-phenylacetic acid (PAA) on T47D human breast cancer cells, testing their antioxidant activity and a number of possible mechanisms involved (interaction with membrane and intracellular receptors, nitric oxide production).

RESULTS

The tested compounds showed a time-dependent and dose-dependent inhibitory effect on cell growth with the following potency: caffeic acid > ferulic acid = protocatechuic acid = PAA > sinapic acid = syringic acid. Caffeic acid and PAA were chosen for further analysis. The antioxidative activity of these phenolic acids in T47D cells does not coincide with their inhibitory effect on tumoral proliferation. No interaction was found with steroid and adrenergic receptors. PAA induced an inhibition of nitric oxide synthase, while caffeic acid competes for binding and results in an inhibition of aryl hydrocarbon receptor-induced CYP1A1 enzyme. Both agents induce apoptosis via the Fas/FasL system.

CONCLUSIONS

Phenolic acids exert a direct antiproliferative action, evident at low concentrations, comparable with those found in biological fluids after ingestion of foods rich in phenolic acids. Furthermore, the direct interaction with the aryl hydrocarbon receptor, the nitric oxide synthase inhibition and their pro-apoptotic effect provide some insights into their biological mode of action.

Anti-HIV activity of olive leaf extract (OLE) and modulation of host cell gene expression by HIV-1 infection and OLE treatment

We investigated the antiviral activity of olive leaf extract (OLE) preparations standardized by liquid chromatography-coupled mass spectrometry (LC-MS) against HIV-1 infection and replication. We find that OLE inhibits acute infection and cell-to-cell transmission of HIV-1 as assayed by syncytia formation using uninfected MT2 cells co-cultured with HIV-1-infected H9 T lymphocytes. OLE also inhibits HIV-1 replication as assayed by p24 expression in infected H9 cells. These anti-HIV effects of OLE are dose dependent, with EC(50)s of around 0.2 microg/ml. In the effective dose range, no cytotoxicity on uninfected target cells was detected. The therapeutic index of OLE is above 5000. To identify viral and host targets for OLE, we characterized gene expression profiles associated with HIV-1 infection and OLE treatment using cDNA microarrays. HIV-1 infection modulates the expression patterns of cellular genes involved in apoptosis, stress, cytokine, protein kinase C, and hedgehog signaling. HIV-1 infection up-regulates the expression of the heat-shock proteins hsp27 and hsp90, the DNA damage inducible transcript 1 gadd45, the p53-binding protein mdm2, and the hedgehog signal protein patched 1, while it down-regulates the expression of the anti-apoptotic BCL2-associated X protein Bax. Treatment with OLE reverses many of these HIV-1 infection-associated changes. Treatment of HIV-1-infected cells with OLE also up-regulates the expression of the apoptosis inhibitor proteins IAP1 and 2, as well as the calcium and protein kinase C pathway signaling molecules IL-2, IL-2Ralpha, and ornithine decarboxylase ODC1.

Exchanging carbohydrates for monounsaturated fats in energy-restricted diets: effects on metabolic profile and other cardiovascular risk factors

OBJECTIVE

To investigate whether improvements in cardiovascular risk factors, as observed in energy-balance conditions after exchanging carbohydrates (CHO) for monounsaturated (MUFA) fats, are also observed in energy-restricted conditions.

DESIGN

Longitudinal, clinical intervention study using two types of energy-restricted diets (-30% of initial energy intake) with similar levels of saturated and polyunsaturated fats: a high CHO diet (55% of energy from CHOs, 10% from MUFAs) and a high MUFA diet (40% of energy from CHOs, 25% from MUFAs).

SUBJECTS

A total of 32 overweight subjects (nine males, 23 females, BMI: 26-45 kg/m(2)).

MEASUREMENTS

Body weight, serum lipids, fasting plasma insulin and phospholipid fatty acid composition of red blood cells were measured at baseline and after 8 weeks. Various oxidative status parameters (plasma lipid hydroperoxides, total plasma antioxidant capacity, plasma uric acid and vitamin E) and serum-induced smooth muscular cell (SMC) proliferation were also measured at these time points.

RESULTS

Weight loss (1.1 kg/week over the first 4 weeks and 6.7 kg at week 8) was not significantly affected by the diet composition. Both diets reduced significantly total serum cholesterol, but the MUFA-rich diet showed better effects on fasting serum triacylglycerol (TG) than the CHO-rich diet: 1.18 vs 1.51 mmol/l for the MUFA-rich diet (after vs before, P<0.05) and 1.42 vs 1.62 for the CHO-rich diet. After 8 weeks, plasma vitamin E concentrations were positively associated with the oleic acid level of red blood cell phospholipids and showed opposite variations in both diets (increase with the MUFA-rich diet and decrease with the CHO-rich diet). Relative changes in SMC proliferation induced by sera were negatively associated with the ratio oleic:linoleic acid of red blood cell phospholipids and were significantly higher with the CHO-rich diet.

CONCLUSIONS

The MUFA-rich diet showed better effects on serum TG than the CHO-rich diet, even with energy restriction and weight loss. The results suggest also a protective effect of oleic acid on oxidative stress and SMC proliferation, two other important cardiovascular risk factors.

Biological activity of some naturally occurring resins, gums and pigments against in vitro LDL oxidation

Naturally occurring gums and resins with beneficial pharmaceutical and nutraceutical properties were tested for their possible protective effect against copper-induced LDL oxidation in vitro. Chiosmastic gum (CMG) (Pistacia lentiscus var. Chia resin) was the most effective in protecting human LDL from oxidation. The minimum and maximum doses for the saturation phenomena of inhibition of LDL oxidation were 2.5 mg and 50 mg CMG (75.3% and 99.9%, respectively). The methanol/water extract of CMG was the most effective compared with other solvent combinations. CMG when fractionated in order to determine a structure-activity relationship showed that the total mastic essential oil, collofonium-like residue and acidic fractions of CMG exhibited a high protective activity ranging from 65.0% to 77.8%. The other natural gums and resins (CMG resin 'liquid collection', P. terebinthus var. Chia resin, dammar resin, acacia gum, tragacanth gum, storax gum) also tested as above, showed 27.0%-78.8% of the maximum LDL protection. The other naturally occurring substances, i.e. triterpenes (amyrin, oleanolic acid, ursolic acid, lupeol, 18-a-glycyrrhetinic acid) and hydroxynaphthoquinones (naphthazarin, shikonin and alkannin) showed 53.5%-78.8% and 27.0%-64.1% LDL protective activity, respectively. The combination effects (68.7%-76.2% LDL protection) of ursolic-, oleanolic- and ursodeoxycholic- acids were almost equal to the effect (75.3%) of the CMG extract in comparable doses.

In vitro cytotoxicity to human cells in culture of some phenolics from olive oil

The neutral red in vitro cytotoxicity assay was used to evaluate the comparative responses of human cells isolated from tissues of the oral cavity to olive oil phenolics. The cell lines used included normal gingival fibroblasts, immortalized, nontumorigenic gingival epithelial cells, and carcinoma cells from the salivary gland. No differences in the relative sensitivities to the phenolics amongst the three cell types were noted. In general, for all cell types, the sequence of increasing cytotoxicity was: oleuropein aglycone>oleuropein glycoside, caffeic acid>o-coumaric acid>cinnamic acid>>tyrosol, syringic acid, protocatechuic acid, vanillic acid. Cytotoxicity was noted only at phenolic concentrations far exceeding those attainable after habitual consumption, thus indicating that consumption of phenol-rich olive oil is safe.

Identification of phenolic compounds in tissues of the novel olive cultivar hardy's mammoth

A methodological approach to phenolic profiling making extensive use of LC-MS with extracted ion chromatograms was applied to extracts of five different olive tissues: pulp, seed, stone, new-season leaves, and old-season leaves. Tissue extracts of the cultivars Hardy's Mammoth, Corregiola, Verdale, and Manzanillo were analyzed by HPLC with UV and ESI MS detection. Chromatograms of samples of green Hardy's Mammoth drupes, a uniquely Australian olive cultivar, were dominated by a large, broad peak. This peak was not attributable to oleuropein, which is usually the dominant phenolic compound in green olive fruit, but the phenolic compound I. This compound was isolated by semipreparative HPLC and characterized by 1D- and 2D-NMR. Extraction studies showed that the compound was not likely to be an artifact of an enzymatic degradation process. Tritium labeling studies were used to establish a possible relationship between the biosynthesis of I and oleuropein.

The biochemistry and medical significance of the flavonoids

Flavonoids are plant pigments that are synthesised from phenylalanine, generally display marvelous colors known from flower petals, mostly emit brilliant fluorescence when they are excited by UV light, and are ubiquitous to green plant cells. The flavonoids are used by botanists for taxonomical classification. They regulate plant growth by inhibition of the exocytosis of the auxin indolyl acetic acid, as well as by induction of gene expression, and they influence other biological cells in numerous ways. Flavonoids inhibit or kill many bacterial strains, inhibit important viral enzymes, such as reverse transcriptase and protease, and destroy some pathogenic protozoans. Yet, their toxicity to animal cells is low. Flavonoids are major functional components of many herbal and insect preparations for medical use, e.g., propolis (bee's glue) and honey, which have been used since ancient times. The daily intake of flavonoids with normal food, especially fruit and vegetables, is 1-2 g. Modern authorised physicians are increasing their use of pure flavonoids to treat many important common diseases, due to their proven ability to inhibit specific enzymes, to simulate some hormones and neurotransmitters, and to scavenge free radicals.

In vitro antimycoplasmal activity of oleuropein

The activity of oleuropein, a phenolic glycoside contained in olive oil, was investigated in vitro against Mycoplasma hominis, Mycoplasma fermentans, Mycoplasma pneumoniae and Mycoplasma pirum. Oleuropein inhibited mycoplasmas at concentrations from 20 to 320 mg/l. The MICs of oleuropein to M. pneumoniae, M. pirum, M. hominis and M. fermentans were 160, 320, 20 and 20 mg/l, respectively.

Olive oil phenolics: effects on DNA oxidation and redox enzyme mRNA in prostate cells

Hydroxytyrosol, tyrosol and caffeic acid effects on hydrogen peroxide-induced DNA damage, hydroperoxide generation and redox enzyme gene expression were studied in oxidative-stress-sensitive human prostate cells (PC3). Hydroxytyrosol led to lower levels of hydroperoxides, DNA damage, and mRNA levels of classic glutathione peroxidase (GPx) for all the studied concentrations. Only hydroxytyrosol was effective at low concentrations (10 microm). Tyrosol reduced DNA oxidation only at high (>50 microm) concentrations and increased hydroperoxides, GPx and phospholipid hydroperoxide GPx mRNA levels. Caffeic acid elicited effects between those of the other two phenolics. Results indicate that hydroxytyrosol is the only significant antioxidant phenolic in olive oil and may be the major component accounting for its beneficial properties. Tyrosol appeared to exhibit pro-oxidant effects (only at high concentrations) and caffeic acid was neutral. Both number and position of hydroxyl groups appear to play a role in the cellular effects of hydroxytyrosol.

The role of antioxidants in the Mediterranean diet

Traditional Mediterranean diets, as opposed to North European and American diets, include a significantly large amount of plant foods; this notable difference between the two eating styles, despite the similarities among other classic risk factors for coronary heart disease (CHD) such as high plasma cholesterol levels, has been associated with a lower risk of developing the CHD and certain cancers. The involvement of excessive free radical production and the great number of epidemiologic studies linking antioxidant intake with a reduced incidence of the above-mentioned diseases indicate that dietary antioxidants likely play a protective role. Because diets in the Mediterranean are (or better yet, were) characterized by abundant plant foods (fruits, vegetables, breads, nuts, seeds; wine and olive oil), this article includes a review of the potential activities of dietary antioxidants, which are plentiful in Mediterranean diets, and wine as related to human disease.

Biophenols in table olives

Unprocessed olives are well-known sources of phenolic antioxidants with important biological properties. Processing methods to prepare table olives may cause a reduction of valuable phenols and may deprive the food of precious biological functions. The present work was undertaken to evaluate table olives produced in Greece as sources of biophenols. Commercially available olives were analyzed for their total phenol content by using the Folin-Ciocalteu reagent and for individual phenols by RP-HPLC. Samples were Spanish-style green olives in brine, Greek-style naturally black olives in brine, and Kalamata olives in brine. Most of the types of olives analyzed were found to be good sources of phenols. Hydroxytyrosol, tyrosol, and luteolin were the prevailing phenols in almost all of the samples examined. High levels of hydroxytyrosol were determined mainly in Kalamata olives and Spanish-style green olives, cultivar Chalkidiki (250-760 mg/kg).

Effect of freeze dried extract of Olea europaea on the pituitary-thyroid axis in rats

The effect of an aqueous extract of olive (Olea europaea) leaf on the thyroid activity was studied. The results suggest a stimulatory action of the extract on the thyroid, unrelated to the pituitary.

Antioxidant and other biological activities of phenols from olives and olive oil

Olive oil is the principal source of fats in the Mediterranean diet, which has been associated with a lower incidence of coronary heart disease and certain cancers. Phenolic compounds, e.g., hydroxytyrosol and oleuropein, in extra-virgin olive oil are responsible for its peculiar pungent taste and for its high stability. Recent findings demonstrate that olive oil phenolics are powerful antioxidants, both in vitro and in vivo, and possess other potent biological activities that could partially account for the observed healthful effects of the Mediterranean diet.