Inhibition of leukocyte leukotriene B4 production by an olive oil-derived phenol identified by mass-spectrometry

Enhancement of the biological activity of hydroxytyrosol through its oxidation by laccase from Trametes versicolor

The laccase-catalyzed oxidation of hydroxytyrosol (HT) towards the formation of its bioactive oligomer derivatives was investigated. The biocatalytic oligomerization was catalyzed by laccase from Trametes versicolor in aqueous or various water-miscible organic solvents and deep eutectic solvent (DES)-based media. Mass Spectroscopy and Nuclear Magnetic Resonance were used for the characterization of the products. The solvent system used significantly affects the degree of HT oligomerization. The use of 50 % v/v methanol favored the production of the HT dimer, while other organic solvents as well as DESs led to the formation of hydroxytyrosol trimer and other oligomers. In vitro studies showed that the HT dimer exhibits 3- to 4-fold enhanced antibacterial activity against Gram-positive and Gram-negative bacteria compared to the parent compound. Moreover, the ability of HT dimer to inhibit the activity of soybean lipoxygenase and Candida rugosa lipase was 1.5-fold higher than HT, while molecular docking supported these results. Furthermore, HT dimer showed reduced cytotoxicity against HEK293 cells and exhibited a strong ability to inhibit ROS formation. The enhanced bioactivity of HT dimer indicates that this compound could be considered for use in cosmetics, skin-care products, and nutraceuticals.

Hydroxytyrosol Dimers from Medicinal Insect Blaps Rynchopetera and the in Vitro Cytotoxic Activity

The edible Blaps rynchopetera Fairmaire is widely used for its various medicinal effects. From its ethyl acetate fraction, three new hydroxytyrosol dimers, rynchopeterine H (1), rynchopeterine I (2) and trans-2-(3,4-dihydroxy-phenyl)-3-hydroxy-7-(2-hydroxyethyl)-1,4-benzdioxane (3), together with four known similar dimers were obtained by chromatography of silica gel and Sephadex LH-20. Their structures were identified by HRESIMS, 1D and 2D NMR spectra analysis. Compounds 1-4 were obtained as a mixture, and cytotoxicity screening for HepG2, Caco-2, U251, AGS, B16 and Bel-7402 cell lines showed that the mixture of compounds 1-4 exhibited significantly selective cytotoxicity and good inhibitory activity on the proliferation of mouse melanoma cells (B16) with an IC50 value of 27.37 μg·mL−1.

Targeting Mammalian 5-Lipoxygenase by Dietary Phenolics as an Anti-Inflammatory Mechanism: A Systematic Review

5-Lipoxygenase (5-LOX) plays a key role in inflammation through the biosynthesis of leukotrienes and other lipid mediators. Current evidence suggests that dietary (poly)phenols exert a beneficial impact on human health through anti-inflammatory activities. Their mechanisms of action have mostly been associated with the modulation of pro-inflammatory cytokines (TNF-α, IL-1β), prostaglandins (PGE2), and the interaction with NF-κB and cyclooxygenase 2 (COX-2) pathways. Much less is known about the 5-lipoxygenase (5-LOX) pathway as a target of dietary (poly)phenols. This systematic review aimed to summarize how dietary (poly)phenols target the 5-LOX pathway in preclinical and human studies. The number of studies identified is low (5, 24, and 127 human, animal, and cellular studies, respectively) compared to the thousands of studies focusing on the COX-2 pathway. Some (poly)phenolics such as caffeic acid, hydroxytyrosol, resveratrol, curcumin, nordihydroguaiaretic acid (NDGA), and quercetin have been reported to reduce the formation of 5-LOX eicosanoids in vitro. However, the in vivo evidence is inconclusive because of the low number of studies and the difficulty of attributing effects to (poly)phenols. Therefore, increasing the number of studies targeting the 5-LOX pathway would largely expand our knowledge on the anti-inflammatory mechanisms of (poly)phenols.

Arachidonate 12-lipoxygenase and 12-hydroxyeicosatetraenoic acid contribute to stromal aging-induced progression of pancreatic cancer

The incidence of pancreatic cancer increases with age, suggesting that chronological aging is a significant risk factor for this disease. Fibroblasts are the major nonmalignant cell type in the stroma of human pancreatic ductal adenocarcinoma (PDAC). In this study, we investigated whether the chronological aging of normal human fibroblasts (NHFs), a previously underappreciated area in pancreatic cancer research, influences the progression and therapeutic outcomes of PDAC. Results from experiments with murine xenografts and 2D and 3D co-cultures of NHFs and PDAC cells revealed that older NHFs stimulate proliferation of and confer resistance to radiation therapy of PDAC. MS-based metabolite analysis indicated that older NHFs have significantly increased arachidonic acid 12-lipoxygenase (ALOX12) expression and elevated levels of its mitogenic metabolite, 12-(S)-hydroxy-5,8,10,14-eicosatetraenoic acid (12-(S)-HETE) compared with their younger counterparts. In co-cultures with older rather than with younger NHFs, PDAC cells exhibited increases in mitogen-activated protein kinase signaling and cellular metabolism, as well as a lower oxidation state that correlated with their enhanced proliferation and resistance to radiation therapy. Expression of ALOX12 was found to be significantly lower in PDAC cell lines and tumor biopsies, suggesting that PDAC cells rely on a stromal supply of mitogens for their proliferative needs. Pharmacological (hydroxytyrosol) and molecular (siRNA) interventions of ALOX12 in older NHFs suppressed their ability to stimulate proliferation of PDAC cells. We conclude that chronological aging of NHFs contributes to PDAC progression and that ALOX12 and 12-(S)-HETE may be potential stromal targets for interventions that seek to halt progression and improve therapy outcomes.

Molecular pathways involved in lymphedema: Hydroxytyrosol as a candidate natural compound for treating the effects of lymph accumulation

Lymphedema is a chronic accumulation of interstitial fluid due to inefficient lymph drainage. Major causes of lymphedema are malformations of lymphatic vessels, trauma, toxic damage and surgery. The swelling typically affects the limbs. Lymphedema may be primary, caused by genetic mutations and relatively rare, or secondary (acquired), due to external causes such as infections or surgery. Fluid accumulation induces pathological changes: activation of the inflammatory cascade, immune cell infiltration, tissue fibrosis, adipose accumulation. We focused on the inflammatory phenotype mediated by leukotriene B4, a lipid mediator of the inflammatory pathway, and the potential therapeutic effect of hydroxytyrosol. We conducted an electronic search in PubMed using "lymphedema", "lymphedema pathway", "hydroxytyrosol" as keywords. We found that lymphedema deregulates at least six molecular pathways and that hydroxytyrosol, a compound with antioxidant activity, can improve endothelial dysfunction, hemostatic and lipid profiles, and decrease oxidative stress and inflammation through inhibition of leukotriene B4 activity. This review is the first to highlight the possibility of using hydroxytyrosol to treat the secondary effects of lymphedema, especially inflammation. The possible effects of hydroxytyrosol on lymphedema should be tested in vitro and in vivo to find the best way to treat patients with lymphedema in order to improve their health status.

In vitro Anti-inflammatory Activity of Ligustrum vulgare Extracts and Their Analytical Characterization

Interest in the anti-inflammatory effects of Ligustrum vulgare L., which has been used traditionally in China and Japan prompted us to determine anti-inflammatory effects of the plant's compounds in leukocytes. The leaves of L. vulgare were used to prepare a decoction which was successively extracted with organic solvents (dichloromethane (DCM), n-butanol, ethyl acetate) using liquid-liquid partition. Extracts were tested for inhibition of LTB4, resp. PGE2 biosynthesis. Each extract was evaluated for its in vitro cyclooxygenase-1/2 (COX-1/2) inhibitory activity using assays with purified COX-1 and COX-2 enzymes, as well as for their LTB4 formation inhibitory activity using an assay with activated human neutrophil granulocytes. All extracts reported inhibitory actions against COXs in comparison with the synthetic inhibitors NS-398 (IC50 = 2.6 μM) and indomethacin (IC50 = 0.9 μM). The dichloromethane extract of privet leaves showed a considerable inhibitory effect against COX-1 and COX-2 enzyme activity. The DCM extract revealed 2.7 times higher inhibitory activity against LTB4 formation in comparison with the known specific LT inhibitor zileuton (IC50 = 5.0 μM). Additionally, oleuropein and echinacoside were detected by HPLC-DAD and LC-MS in the Ligustrum vulgare leaves. Both compounds exhibited weak inhibitory activity on cyclooxygenases and leukotriene formation.

Mechanisms of action of phenolic compounds in olive

Olive oil, an oil rich in monounsaturated fatty acids (MUFCs) and minor constituents including phenolic compounds, is a major component of the Mediterranean diet. The potential health benefits of the Mediterranean diet were highlighted by the seminal Seven Countries Study, and more contemporary research has identified olive oil as a major element responsible for these effects. It is emerging that the phenolic compounds are the most likely candidates accounting for the cardioprotective and cancer preventative effects of extra virgin olive oil (EVOO). In particular, the phenolic compound, hydroxytyrosol has been identified as one of the most potent antioxidants found in olive oil. This review will briefly consider historical aspects of olive oil research and the biological properties of phenolic compounds in olive oil will be discussed. The focus of the discussion will be related to the mechanisms of action of hydroxytyrosol. Studies have demonstrated that hydroxytyrosol induces apoptosis and cell cycle arrest in cancer cells. Further, research has shown that hydroxytyrosol can prevent cardiovascular disease by reducing the expression of adhesion molecules on endothelial cells and preventing the oxidation of low-density lipoprotein (LDL). The molecular mechanisms accounting for these effects are reviewed.

The Mediterranean diet: effects on proteins that mediate fatty acid metabolism in the colon

A Mediterranean diet appears to have health benefits in many domains of human health, mediated perhaps by its anti-inflammatory effects. Metabolism of fatty acids and subsequent eicosanoid production is a key mechanism by which a Mediterranean diet can exert anti-inflammatory effects. Both dietary fatty acids and fatty acid metabolism determine fatty acid availability for cyclooxygenase- and lipoxygenase-dependent production of eicosanoids, namely prostaglandins and leukotrienes. In dietary intervention studies and in observational studies of the Mediterranean diet, blood levels of fatty acids do reflect dietary intakes but are attenuated. Small differences in fatty acid levels, however, appear to be important, especially when exposures occur over long periods of time. This review summarizes how fat intakes from a Greek-style Mediterranean diet can be expected to affect fatty acid metabolizing proteins, with an emphasis on the metabolic pathways that lead to the formation of proinflammatory eicosanoids. The proteins involved in these pathways are ripe for investigation using proteomic approaches and may be targets for colon cancer prevention.

Hydroxytyrosol: from laboratory investigations to future clinical trials

Mediterranean countries have lower rates of mortality from cardiovascular disease and cancer than Northern European or other Western countries. This has been attributed, at least in part, to the so-called Mediterranean diet, which is composed of specific local foods, including olive oil. Traditionally, many beneficial properties associated with this oil have been ascribed to its high oleic acid content. Today, it is clear that many of the beneficial effects of ingesting virgin olive oil are due to its minor compounds. This review summarizes the existing knowledge concerning the chemistry, pharmacokinetics, and toxicology of hydroxytyrosol, a minor compound of virgin olive oil, as well as this compound's importance for health. The main findings in terms of its beneficial effects in cardiovascular disease and cancer, including its properties against inflammation and platelet aggregation, are emphasized. New evidence and strategies regarding the use of hydroxytyrosol as a natural drug for the prevention and treatment of diseases with high incidences in Western countries are also presented.

Nutritional benefit of olive oil: the biological effects of hydroxytyrosol and its arylating quinone adducts

Olive oil is the essential component of the Mediterranean diet, a nutritional regimen gaining ever-increasing renown for its beneficial effects on inflammation, cardiovascular disease, and cancer. A unique characteristic of olive oil is its enrichment in oleuropein, a member of the secoiridoid family, which hydrolyzes to the catechol hydroxytyrosol and functions as a hydrophilic phenolic antioxidant that is oxidized to its catechol quinone during redox cycling. Little effort has been spent on exploring the biological properties of the catechol hydroxytyrosol quinone, a strong arylating electrophile that forms Michael adducts with thiol nucleophiles in glutathione and proteins. This study compares the chemical and biological characteristics of hydroxytyrosol with those of the tocopherol family in which Michael adducts of arylating desmethyltocopherol quinones have been identified and correlated with biologic properties including cytotoxicity and induction of endoplasmic reticulum stress. It is noted that hydroxytyrosol and desmethyltocopherols share many similarities, suggesting that Michael adduct formation by an arylating quinone electrophile may contribute to the biological properties of both families, including the unique nutritional benefit of olive oil.

Phenolic compounds and antioxidant activity of Italian extra virgin olive oil Monti Iblei

The profile of phenolic compounds, antioxidant capacity, oxidative stability, and chemical characteristics (free acidity, peroxide value, specific extinction K232 and K270 values, and DeltaK) of 22 commercial extra virgin olive oil (EVOO) samples coming from the denomination of protected origin (DPO) Monti Iblei and obtained from olives harvested in the period September-December 2005 in the production area of the province of Siracusa (Sicily, Italy) were evaluated. The content of total phenols, expressed as gallic acid equivalents, ranged from 14.80 to 121.20 mg/100 g, with a mean value of 53.72 mg/100 g, mainly attributable to deacetoxyligstroside aglycone, deacetoxyoleuropein aglycone, oleuropein aglycone, and ligstroside aglycone. The mean values of Trolox equivalent antioxidant capacity (TEAC) and of oxidative stability were 54.76 and 11.99 hours, respectively. Both TEAC and oxidative stability were positively correlated to the phenol content and to the percentage of inclusion of the olive cultivar "Tonda Iblea." The high mean content of phenols, besides conferring prolonged oxidative stability, likely confers to the DPO Monti Iblei EVOO marked potential beneficial effects for human health.

One-month administration of hydroxytyrosol, a phenolic antioxidant present in olive oil, to hyperlipemic rabbits improves blood lipid profile, antioxidant status and reduces atherosclerosis development

The present study analysed the effects of hydroxytyrosol (HT) on blood lipids, antioxidant status and the progression of aortic lesions in hyperlipemic rabbits. Sixty-four rabbits were distributed into eight groups of animals (n = 8). Animal groups C, A and H were fed for 1-month with a control diet containing sunflower oil (C), an atherogenic diet (A) high in saturated fat and cholesterol or the A diet together with HT, respectively. The other five groups were fed for 2-months with diets C or A (groups CC or AA, respectively), or for 1-month with the A-diet followed by a further month with diet C, extra virgin olive oil diet (O) or diet C with HT (groups AC, AO and AH, respectively). Four milligram of HT/kg body weight were used in the study. Fifty and 42% decrease in total cholesterol and triacylglycerols, respectively, and a 2.3-fold increase in HDL-cholesterol were observed in the AH group but not in the H group. The HT-supplemented groups improved their antioxidant status and reduced the size of atherosclerotic lesions measured as intimal layer areas of the aortic arch when compared with control animals. We conclude that HT supplementation may have cardioprotective effects in vivo.

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.

Efficacy and safety of an olive oil-based intravenous fat emulsion in adult patients on home parenteral nutrition

BACKGROUND

The most frequently used intravenous lipid emulsions are composed of 100% long chain triacylglycerols from soybean oil or of 50% long chain triacylglycerols-50% medium chain triacylglycerols. A newer emulsion, ClinOleic 20% containing 80% olive oil and 20% soybean oil, was suggested to reduce lipid peroxidation and immune function impairment.

AIM

To assess ClinOleic 20%'s efficacy, safety and effect upon systemic inflammatory parameters in adults on home parenteral nutrition.

METHODS

In stable home parenteral nutrition patients, the initial intravenous lipid emulsion was changed for ClinOleic 20%. Nutritional status, clinical and biological tolerance, and systemic inflammatory markers were analysed before and after 1 and 3 months of home parenteral nutrition, with ClinOleic 20% as intravenous lipid emulsion.

RESULTS

Clinical and biological nutritional markers and inflammatory parameters did not differ between day 0 and month +3. There was no essential fatty acids deficiency. No side-effects were reported. Three of five patients presenting with migraine during home parenteral nutrition infusion at day 0 felt consistently better at month +3.

CONCLUSIONS

ClinOleic 20% is safe and efficient in adult home parenteral nutrition. It maintains normal essential fatty acids status and did not influence inflammatory parameters. In contrast to studies in preterm infants or paediatric patients, no effect on vitamin E concentration or lipid peroxidation was observed.

Topical application of natural honey, beeswax and olive oil mixture for atopic dermatitis or psoriasis: partially controlled, single-blinded study

OBJECTIVES

To investigate the effects of honey, olive oil and beeswax mixture on patients with atopic dermatitis (AD) or psoriasis vulgaris (PV).

MATERIALS AND METHODS

Twenty-one patients with dermatitis and 18 patients with psoriasis were entered for patient-blinded, partially controlled study; 11 patients with dermatitis used topical betamethasone esters and 10 patients with psoriasis used clobetasol propionate. Honey mixture contained honey, beeswax and olive oil (1:1:1). Mixtures A, B, and C contained honey mixture with the corticosteroids ointment in a ratio of 1:1, 2:1, and 3:1 respectively. Patients with dermatitis were subjected to controlled bilateral half-body comparison to evaluate the efficacy of honey mixture against Vaseline, or mixture A against Vaseline-betamethasone esters mixture (1:1) in patients using topical corticosteroid treatment. In patients with psoriasis, the effect of honey mixture was compared with paraffin in an individual right/left-sites comparison, or mixture A against paraffin-clobetasol propionate mixture (1:1) in patients using corticosteroid topical therapy. In dermatitis, body lesions on right or left half-body were assessed for erythema, scaling, lichenification, excoriation, indurations, oozing and itching on a 0-4 points scale. In psoriasis, lesions of selected site were assessed for redness, scaling, thickening and itching, on a 0-4 points scale.

RESULTS

In honey mixture group, 8/10 patients with dermatitis showed significant improvement after 2 weeks, and 5/11 patients pretreated with betamethasone esters showed no deterioration upon 75% reduction of corticosteroid doses with use of mixture C. In psoriasis, 5/8 patients showed a significant response to honey mixture. In patients using clobetasol propionate, 5/10 patients showed no deterioration upon 75% reduction of corticosteroid doses with use of mixture C.

CONCLUSION

Honey mixture appears useful in the management of dermatitis and psoriasis vulgaris.

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.

N-3 fatty acids for the treatment of inflammatory bowel diseases

The aim of the present paper is to briefly review the literature relating to clinical studies of the use of polyunsaturated long-chain fatty acids in the treatment of inflammatory bowel diseases (IBD) such as ulcerative colitis and Crohn's disease. The reasons for the discrepancies in the findings could be related to the different study designs, different treatments, overlapping of treatment effects, as well as the variety of treatment formulations and doses used, which have led to results that are, in certain instances, very difficult to explain. Emphasis on a treatment formulation which reduces the incidence of side effects, together with careful selection of patients and experimental design, seems to be associated with benefits, and these studies point to the therapeutic potential for these lipids in the therapy of IBD. It is possible that these fatty acids act by reducing low-grade active inflammation rather than by preventing reinitiation of the inflammatory process from a truly quiescent state. Whether this treatment is applicable to all IBD patients has not been fully elucidated. Nevertheless, taken together, all these studies suggest the effectiveness of these new therapeutic approaches, not only when conventional treatment fails or when it is not possible to treat chronically, but also, in some instances, as first choice.

Major phenolic compounds in olive oil: metabolism and health effects

It has been postulated that the components in olive oil in the Mediterranean diet, a diet which is largely vegetarian in nature, can contribute to the lower incidence of coronary heart disease and prostate and colon cancers. The Mediterranean diet includes the consumption of large amounts of olive oil. Olive oil is a source of at least 30 phenolic compounds. The major phenolic compounds in olive oil are oleuropein, hydroxytyrosol and tyrosol. Recently there has been a surge in the number of publications that has investigated their biological properties. The phenolic compounds present in olive oil are strong antioxidants and radical scavengers. Olive "waste water" also possesses compounds which are strong antioxidant and radical scavengers. Typically, hydroxytyrosol is a superior antioxidant and radical scavenger to oleuropein and tyrosol. Hydroxytyrosol and oleuropein have antimicrobial activity against ATTC bacterial strains and clinical bacterial strains. Recent syntheses of labeled and unlabelled hydroxytyrosol coupled with superior analytical techniques have enabled its absorption and metabolism to be studied. It has recently been found that hydroxytyosol is renally excreted unchanged and as the following metabolites as its glucuronide conjugate, sulfate conjugate, homovanillic acid, homovanillic alcohol, 3,4-dihydroxyphenylacetic acid and 3,4-dihydroxyphenylacetaldehyde. Studies with tyrosol have shown that it is excreted unchanged and as its conjugates. This review summarizes the antioxidant abilities; the scavenging abilities and the biological fates of hydroxytyrosol, oleuropein and tyrosol which have been published in recent years.

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.

Cancer chemoprevention by hydroxytyrosol isolated from virgin olive oil through G1 cell cycle arrest and apoptosis

Recent epidemiological evidence and animal studies suggest a relationship between the intake of olive oil and a reduced risk of several malignancies. The present study assesses the effect of hydroxytyrosol, a major antioxidant compound of virgin olive oil, on proliferation, apoptosis and cell cycle of tumour cells. Hydroxytyrosol inhibited proliferation of both human promyelocytic leukaemia cells HL60 and colon adenocarcinoma cells HT29 and HT29 clone 19A. The con-centrations of hydroxytyrosol which inhibited 50% of cell proliferation were approximately 50 and approximately 750 micromol/l for HL60 and both HT29 and HT29 clone 19A cells, respectively. At concentrations ranging from 50 to 100 micromol/l, hydroxytyrosol induced an appreciable apoptosis in HL60 cells after 24 h of incubation as evidenced by flow cytometry, fluorescence microscopy and internucleosomal DNA fragmentation. Interestingly, no effect on apoptosis was observed after similar treatment of freshly isolated human lymphocytes and polymorphonuclear cells. The DNA cell cycle analysis, quantified by flow cytometry, showed that the treatment of HL60 cells with hydroxytyrosol 50-100 micromol/l arrested the cells in the G0/G1 phase with a concomitant decrease in the cell percentage in the S and G2/M phases. These results support the hypothesis that hydroxytyrosol may exert a protective activity against cancer by arresting the cell cycle and inducing apoptosis in tumour cells, and suggest that hydroxytyrosol, an important component of virgin olive oil, may be responsible for its anticancer activity.