Fast separation and determination of tyrosol, hydroxytyrosol and other phenolic compounds in extra-virgin olive oil by capillary zone electrophoresis with ultraviolet-diode array detection

Boric acids decorated polymers with Au nanoparticle anchor assisted laser desorption/ionization for qualitive and quantitative analysis of hydroxytyrosol in red wines

Hydroxytyrosol possesses a variety of biological and pharmacological activities that are beneficial to human health. However, the methodologies for its detection always suffered from problems. In this work, the gold nanoparticle modified polymer decorated with boric acids (pMBA/VPBA@Au) was synthesized and used both as the adsorbent and matrix to enrich and ionize small molecule substances through surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS). The pMBA/VPBA@Au displayed a low detection limit (8 × 10-6 M) and high selectivity (1:100) for the enrichment of hydroxytyrosol, and the linear correlation curve between the concentration of hydroxytyrosol and the intensity of MS had a good correlation (10-4-10-2 M, R2 = 0.997). Additionally, the pMBA/VPBA@Au was used to quantify hydroxytyrosol in red wines, and the contents were 0.053-0.094 μg/mL. In general, a simple and novel method for the detection of hydroxytyrosol by SALDI-MS using boric acid functionalized polymer was developed for the first time, showing a good practical application value.

Chemoprevention effect of the Mediterranean diet on colorectal cancer: Current studies and future prospects

Colorectal cancer (CRC) is the third most common cancer and the second most deadly cancer worldwide. Nevertheless, more than 70% of CRC cases are resulted from sporadic tumorigenesis and are not inherited. Since adenoma-carcinoma development is a slow process and may take up to 20 years, diet-based chemoprevention could be an effective approach in sporadic CRC. The Mediterranean diet is an example of a healthy diet pattern that consists of a combination of nutraceuticals that prevent several chronic diseases and cancer. Many epidemiological studies have shown the correlation between adherence to the Mediterranean diet and low incidence of CRC. The goal of this review is to shed the light on the anti-inflammatory and anti-colorectal cancer potentials of the natural bioactive compounds derived from the main foods in the Mediterranean diet.

Potential Effects of Phenolic Compounds That Can Be Found in Olive Oil on Wound Healing

The treatment of tissue damage produced by physical, chemical, or mechanical agents involves considerable direct and indirect costs to health care systems. Wound healing involves a series of molecular and cellular events aimed at repairing the defect in tissue integrity. These events can be favored by various natural agents, including the polyphenols in extra virgin olive oil (EVOO). The objective of this study was to review data on the potential effects of different phenolic compounds that can also be found in EVOO on wound healing and closure. Results of in vitro and animal studies demonstrate that polyphenols from different plant species, also present in EVOO, participate in different aspects of wound healing, accelerating this process through their anti-inflammatory, antioxidant, and antimicrobial properties and their stimulation of angiogenic activities required for granulation tissue formation and wound re-epithelialization. These results indicate the potential usefulness of EVOO phenolic compounds for wound treatment, either alone or in combination with other therapies. Human studies are warranted to verify this proposition.

Instrumental Techniques to Classify Olive Oils according to Their Quality

This review includes an update of the publications on quality classification of olive oils into extra, virgin or lampante olive oil categories. Nowadays, the official method to carry out this classification is time-consuming and, sometimes, it is not systematic and/or objective. It is based on conventional physicochemical analysis and on a sensorial tasting of olive oils carried out by a panel of experts. The aim of this review was to explore and give value to the alternative techniques reported in the bibliography to complement the current official methods established for that classification of olive oils. Specifically considered were non-separation and separation analytical techniques which could contribute to correctly classify olive oils according to their physicochemical and/or sensorial characteristics. An in-depth description has been written on the methods used to differentiate these three types of olive oils and the main advantages and disadvantages of the proposed procedures. The techniques here reviewed could be a real and fast option to complement or even substitute some of the analysis included in the official method. Finally, general trends and detected difficulties found to address this issue have been discussed throughout the article.

Tryptophanase gene deficiency improves the application of dioxygenase to 3-(2-hydroxyethyl)catechol production

3-(2-Hydroxyethyl)catechol (HEC) is a polyphenol reported to exhibit skin-lightning and antioxidative effects, and hence is expected to be used as cosmetic and food additives and chemical products such as electronic materials. In this study, we established biocatalytic HEC production from 2-phenylethanol using the dioxygenase whose expression was induced by toluene, CumA, and its flanking dehydrogenase, CumB, from an isolated strain, Pseudomonas sp. K17. Escherichia coli cells coexpressing CumA and CumB were stained blue during cultivation in Luria-Bertani medium, and HEC was not produced upon using the cell-free extracts as biocatalysts, likely resulting from the inhibitory effects of the blue dyes. The disruption of the tryptophanase gene of E. coli was found to repress the generation of the blue dyes, and enhanced HEC production. The blue dyes were extracted from the cell-free extracts, and their molecular formula was C₁₆H₁₀N₂O₃, suggesting they were monooxygenated indigo or its isomers. Although repression of blue dye formation and enhancement of HEC production were observed when cells were cultivated with glucose, the percent yield of HEC was 84% at 20 h, whereas that with tryptophanase disruption strain was 84% at 4 h. It was suggested that tryptophanase gene disruption could contribute to more efficient HEC production.

Use of whole electrophoretic profile and chemometric tools for the differentiation of three olive oil qualities

Olive oil is a liquid fat obtained from olives (the fruit of Olea europea). It is one of the most important ingredients of the Mediterranean diet, due to its health benefits. Depending on its quality, olive oil can be classified as extra virgin (EVOO), virgin (VOO) and lampante (LOO). Currently, an official method defines the quality parameters of the different categories of olive oil using different analytical techniques and a sensory analysis through a Panel Test. However, the evaluation of olive oil quality by tasting panels has some drawbacks, such as the subjectivity of the analysis and the lack of panels accredited outside Spain. For this reason, fast, simple and reliable analytical methods, which can differentiate the categories of olive oil are needed. In this work, the potential of a method using capillary electrophoresis (CE) with ultraviolet (UV) detection as an additional method to the ones already included in the official method has been investigated. The separations were performed using a 45 mM sodium tetraborate buffer (pH 9), and the analytes were measured at 200 nm. For chemometric model construction, the whole electrophoretic profile was processed. It required a correction of migration time shift, which was solved using two internal standards (naphthol and benzoic acid), and a correction of the drift baseline. The results obtained after applying the method to 130 olive oil samples are very promising, achieving success rates above 91%. Finally, the use of all information found in the electropherogram was compared with that based on the selection and integration of only some peaks.

Extraction, Analysis, and Antioxidant Activity Evaluation of Phenolic Compounds in Different Italian Extra-Virgin Olive Oils

The analysis of phenolic compounds in extra virgin olive oils was carried out by high-performance liquid chromatography utilizing photodiode array and mass spectrometry detectors. The chromatographic profile of thirty samples from four Italian Regions highlighted the presence of secoiridoids, phenolic alcohols, flavonoids, and phenolic acid classes. A similar qualitative profile was observed with some differences in peak area and fifteen compounds were tentatively identified. Quantitative analysis was performed by UV detection considering eight standard phenolic compounds. The chromatographic method, after optimization, was validated studying some parameters, e.g., intra-day and inter-day retention time precision, limit of detection, limit of quantification, and linearity. Recovery of the method was performed achieving good results (10 and 50 g·g^-1 with recovery of 72.9⁻92.1% (w/w) and 79.1⁻102.8% (w/w), respectively). In all samples secoiridoids were the main compounds ranging from 85 to more than 99% (w/w) of the total concentration of detected phenolic compounds while phenolic acids accounted for the lowest percentage (0.1⁻0.6%, w/w). Finally, total concentration of phenolic compounds and antioxidant activity were determined with different chemical assays. A good and significant correlation among total phenolic compound concentration and antioxidant activity was observed. A significant different phenolic compound concentration and antioxidant activity was determined between samples from Puglia and Sicily. This was studied performing statistical analysis by one-way analysis of variance (ANOVA) followed by Bonferroni post-hoc test.

Evaluation of activated composite membranes for the facilitated transport of phenol

In this work the results on the first use of an activated composite membrane (ACM) containing Cyanex 923 for the extraction and transport of phenol are presented. A new dense layer-ACM configuration constituted by piperazine showed better stability than that prepared with 1,3-phenylenediamine. The effects of several parameters on the transport of phenol such as feed phase pH, carrier concentration and stripping phase composition were evaluated. The performance of the membrane was also evaluated during continuous additions of phenol and for a long period of time, observing the same rate of extraction and reextraction. Moreover, phenol transport was evaluated starting from synthetic wastewater of resin production plants type. The results exhibit the potential use of ACMs in the elimination and transport of organic species, even when analyte is initially found in complex solutions.

Authentication and Quantitation of Fraud in Extra Virgin Olive Oils Based on HPLC-UV Fingerprinting and Multivariate Calibration

High performance liquid chromatography method with ultra-violet detection (HPLC-UV) fingerprinting was applied for the analysis and characterization of olive oils, and was performed using a Zorbax Eclipse XDB-C8 reversed-phase column under gradient elution, employing 0.1% formic acid aqueous solution and methanol as mobile phase. More than 130 edible oils, including monovarietal extra-virgin olive oils (EVOOs) and other vegetable oils, were analyzed. Principal component analysis results showed a noticeable discrimination between olive oils and other vegetable oils using raw HPLC-UV chromatographic profiles as data descriptors. However, selected HPLC-UV chromatographic time-window segments were necessary to achieve discrimination among monovarietal EVOOs. Partial least square (PLS) regression was employed to tackle olive oil authentication of Arbequina EVOO adulterated with Picual EVOO, a refined olive oil, and sunflower oil. Highly satisfactory results were obtained after PLS analysis, with overall errors in the quantitation of adulteration in the Arbequina EVOO (minimum 2.5% adulterant) below 2.9%.

Degradation of phenolic compounds by the lignocellulose deconstructing thermoacidophilic bacterium Alicyclobacillus Acidocaldarius

Alicyclobacillus acidocaldarius, a thermoacidophilic bacterium, has a repertoire of thermo- and acid-stable enzymes that deconstruct lignocellulosic compounds. The work presented here describes the ability of A. acidocaldarius to reduce the concentration of the phenolic compounds: phenol, ferulic acid, ρ-coumaric acid and sinapinic acid during growth conditions. The extent and rate of the removal of these compounds were significantly increased by the presence of micro-molar copper concentrations, suggesting activity by copper oxidases that have been identified in the genome of A. acidocaldarius. Substrate removal kinetics was first order for phenol, ferulic acid, ρ-coumaric acid and sinapinic acid in the presence of 50 μM copper sulfate. In addition, laccase enzyme assays of cellular protein fractions suggested significant activity on a lignin analog between the temperatures of 45 and 90 °C. This work shows the potential for A. acidocaldarius to degrade phenolic compounds, demonstrating potential relevance to biofuel production and other industrial processes.

Determination of hydroxytyrosol and tyrosol by liquid chromatography for the quality control of cosmetic products based on olive extracts

An analytical method for the simultaneous determination of hydroxytyrosol and tyrosol in different types of olive extract raw materials and cosmetic cream samples has been developed. The determination was performed by liquid chromatography with UV spectrophotometric detection. Different chromatographic parameters, such as mobile phase pH and composition, oven temperature and different sample preparation variables were studied. The best chromatographic separation was obtained under the following conditions: C18 column set at 35°C and isocratic elution of a mixture ethanol: 1% acetic acid solution at pH 5 (5:95, v/v) as mobile phase pumped at 1 mL min(-1). The detection wavelength was set at 280 nm and the total run time required for the chromatographic analysis was 10 min, except for cosmetic cream samples where 20 min runtime was required (including a cleaning step). The method was satisfactorily applied to 23 samples including solid, water-soluble and fat-soluble olive extracts and cosmetic cream samples containing hydroxytyrosol and tyrosol. Good recoveries (95-107%) and repeatability (1.1-3.6%) were obtained, besides of limits of detection values below the μg mL(-1) level. These good analytical features, as well as its environmentally-friendly characteristics, make the presented method suitable to carry out both the control of the whole manufacture process of raw materials containing the target analytes and the quality control of the finished cosmetic products.

In vivo and in vitro addition of dried olive extract in poultry

A freeze-dried powder from organic olive (Olea europaea) juice extract, contains 8.82% polyphenols and a minimum of 2.5% hydroxytyrosol (3,4-dihydroxyphenylethanol), an effective free radical scavenger and the major antioxidant in the byproduct (dried olive extract, DOE). Myricetin, a bioflavonoid extract from the bark powder of the bayberry tree (Myrica cerifera), also has many beneficial biological properties and antioxidative capacity. While well-known as antioxidants, the capacity of these compounds to retard lipid oxidation in foods containing unsaturated fatty acids has not been widely evaluated. Thus, a study was conducted to assess the capacity of DOE to (1) enhance the growth of poultry, (2) determine the effectiveness of DOE (administered in vivo) as an antioxidant in post-mortem tissue and further processed meat, and (3) compare the in vitro antioxidative capacity of hydroxytyrosol and myricetin. DOE was administered ad libitum in water at 6 and 12 mg per bird per day for 6 weeks in a factorial design: 3 diets (control plus two treatment levels) × 2 blocks × 2 replications. There was no enhancement of feed consumption, body weight (BW), or feed conversion by DOE; overall means for these measurements were 5.49 kg per bird, 3.32 kg per bird, and 1.65 g feed per g live BW, respectively. Diagnostic examinations of two birds per pen at the end of the study revealed no adverse effects due to consumption of DOE, a generally recognized as safe substance. The byproduct, administered in vivo, did not retard lipid oxidation in fresh, heated, or NaCl (1.0% w/w)/heated/stored meat as assessed by absorbance values for thiobarbituric acid reactive substances at 532 nm and 2,2-diphenylpicrylhydrazyl at 517 nm. Both the byproduct and hydroxytyrosol are highly water-soluble and may have been unavailable as an antioxidant in the tissue of broilers that did not consume water for 4-6 h prior to processing. As an additive in processed thigh meat, 6 and 12 mg of DOE (2.5% hydroxytyrosol) per 3 mg of meat, although not as effective as myricetin (95% purity), reduced oxidation. Further assessment revealed that hydroxytyrosol from the DOE, added at (1)/38 the concentration of myricetin, was almost 50% as effective.

Olive oil by capillary electrophoresis: characterization and genuineness

Olive oil, obtained from Olea europaea L. (Oleaceae) fruits, is an important ingredient in the Mediterranean diet. The purpose of this paper is to review and evaluate olive oil analysis using capillary electrophoresis (CE). This review covers a selection of the literature published on this topic over the past decade. The current state of the art of the topic is evaluated, with special emphasis on separation conditions, analysis purpose, and analytes investigated. CE has been used to characterize or to carry out authenticity studies. Particular attention has been focused on the botanical origin because high-quality monovarietal olive oils have been recently introduced on the markets and their quality control requires the development of new and powerful analytical tools as well as new regulations to avoid fraud. CE represents a good compromise between sample throughput, sample volume, satisfactory characterization, and sustainability for the analysis of target compounds present in olive oils.

Antioxidant activity of lignin phenolic compounds extracted from kraft and sulphite black liquors

The antioxidant activity of the phenolic compounds present in industrial black liquors obtained from the two cooking processes (kraft and sulphite) used in Portugal to produce Eucalyptus globulus pulp was evaluated. The black liquors treated at several pH values were extracted with ethyl acetate. Phenolic fractions were further separated by liquid chromatography of the crude extracts of kraft liquor at pH = 6 and sulphite liquor at the original pH. Total phenolic content was determined in terms of gallic acid equivalents (Folin-Ciocalteu colorimetric method), and the antioxidant activity in the crude extracts at several pH values and in the separated fractions was measured using the DPPH test for radical scavenging capacity. The total phenolic content of crude extracts and separated fractions ranged from 92.7 to 181.6 and from 91.6 to 1,099.6 mg GAE/g, respectively, while the antioxidant activity index (AAI) ranged from 2.20 to 3.41 and from 2.21 to 11.47 respectively, showing very strong antioxidant activity in all studied cases. The fractions separated by column chromatography were submitted to mass spectrometry analysis and the results were compared to others in the literature of natural products, mainly from Eucalyptus, and the characteristic bands of functional groups were identified by ¹H-NMR and FTIR. These methods allowed the identification of 17 phenolic compounds.

Prediction of extra virgin olive oil varieties through their phenolic profile. Potential cytotoxic activity against human breast cancer cells

The aim of this work was to develop a rapid resolution liquid chromatography coupled to electrospray ionization time-of-flight mass spectrometry (RRLC-ESI-TOF-MS) method followed by tetrazolium salt (MTT)-based cell viability assays for qualitative and quantitative classification of extra virgin olive oil (EVOO) varieties by phenolic and other polar compound contents as well as for rapid characterization of putative cytotoxic activities against human cancer cells. Five different Spanish EVOO varieties were analyzed, and RRLC-ESI-TOF-MS method was applied for qualitative and quantitative identification of most important phenolic compounds. We finally employed MTT-based cell viability protocol to assess the effects of crude EVOO phenolic extracts (PEs) on the metabolic status of cultured SKBR3 human breast cancer cells. MTT-based cell viability assays revealed a wide range of breast cancer cytotoxic potencies among individual crude PE obtained from EVOO monovarietals. Remarkably, breast cancer cell sensitivity to crude EVOO-PEs was up to 12 times higher in secoiridoids enriched-PE than in secoiridoids-low/null EVOO-PE.

Application and potential of capillary electroseparation methods to determine antioxidant phenolic compounds from plant food material

Antioxidants are one of the most common active ingredients of nutritionally functional foods which can play an important role in the prevention of oxidation and cellular damage inhibiting or delaying the oxidative processes. In recent years there has been an increased interest in the application of antioxidants to medical treatment as information is constantly gathered linking the development of human diseases to oxidative stress. Within antioxidants, phenolic molecules are an important category of compounds, commonly present in a wide variety of plant food materials. Their correct determination is pivotal nowadays and involves their extraction from the sample, analytical separation, identification, quantification and interpretation of the data. The aim of this review is to provide an overview about all the necessary steps of any analytical procedure to achieve the determination of phenolic compounds from plant matrices, paying particular attention to the application and potential of capillary electroseparation methods. Since it is quite complicated to establish a classification of plant food material, and to structure the current review, we will group the different matrices as follows: fruits, vegetables, herbs, spices and medicinal plants, beverages, vegetable oils, cereals, legumes and nuts and other matrices (including cocoa beans and bee products). At the end of the overview, we include two sections to explain the usefulness of the data about phenols provided by capillary electrophoresis and the newest trends.

The Biotransformation of Aromatic Amino Acids by Phoma macrostoma

A search for natural products produced in fermentation cultures of a strain of Phoma macrostoma led to the identification of tyrosol as the major metabolite produced by this organism. The addition of the amino acid tyrosine to growing fermentation cultures of P. macrostoma resulted in an increase in the production of tyrosol. It was subsequently determined that this strain of P. macrostoma was also capable of the biotransformation of other amino acids into similar alcohols.

Chondrocyte autophagy is stimulated by HIF-1 dependent AMPK activation and mTOR suppression

The goal of the study is to examine the relationship between the sensor molecules, Hypoxia Inducible Factor-1 (HIF-1), AMP activated Protein Kinase (AMPK) and mammalian Target of Rapamycin (mTOR) in chondrocyte survival and autophagy. We showed that chondrocytes expressed the energy sensor AMPK-1 and that activation increased with maturation. In addition, we showed that thapsigargin treatment activated AMPK and autophagy in a HIF-1-dependent manner. Using serum-starved AMPK-silenced cells, we demonstrated that AMPK was required for the induction of the autophagic response. We also noted a change in chondrocyte sensitivity to apoptogens, due to activation of caspase-8 and cleavage and activation of the pro-apoptotic protein, BID. To test the hypothesis that AMPK signaling directly promoted autophagy, we inhibited AMPK activity in mTOR silenced cells and showed that while mTOR suppression induced autophagy, AMPK inhibition did not block this activity. Based on these findings, it is concluded that because of the micro-environmental changes experienced by the chondrocyte, autophagy is activated by AMPK in a HIF-1-dependent manner.

Extra virgin olive oil phenolics: absorption, metabolism, and biological activities in the GI tract

Olive oil, a typical ingredient of the Mediterranean diet, possesses many beneficial health effects. The biological activities ascribed to olive oil consumption are associated in part to its phenolics constituents, and mainly linked to the direct or indirect antioxidant activity of olive oil phenolics and their metabolites, which are exerted more efficiently in the gastrointestinal (GI) tract, where dietary phenolics are more concentrated when compared to other organs. In this regard, we present a brief overview of the metabolism, biological activities, and anticancer properties of olive oil phenolics in the GI tract.

Analysis of phenolic compounds in extra virgin olive oil by using reversed-phase capillary electrochromatography

In this work, the simultaneous separation of ten phenolic compounds (protocatechuic, p-coumaric, o-coumaric, vanillic, ferulic, caffeic, syringic acids, hydroxytyrosol, tyrosol and oleuropein) in extra virgin olive oils (EVOOs) by isocratic RP CEC is proposed. A CEC method was optimized in order to completely resolve all the analyzed compounds by studying several experimental parameters. The influence of the stationary phase type (C(18) and C(8) modified silica gel), buffer concentration and pH as well as the organic modifier content of the mobile phase on retention factors, selectivity and efficiency were evaluated in details. A capillary column packed with Cogent bidentate C(18) particles for 23 cm and a mobile phase composed by 100 mM ammonium formate buffer pH 3/H(2)O/ACN (5:65:30 v/v/v) allowed the baseline resolution of the compounds under study in less than 35 min setting the applied voltage and temperature at 22 kV and 20 degrees C, respectively. A study, evaluating the intra- and interday precision as well as LOD and LOQ and method linearity was developed in accordance with the analytical procedures for method validation. LODs were in the range of 0.015-2.5 microg/mL, while calibration curves showed a good linearity (r(2) >0.997). The CEC method was applied to the separation and determination of these compounds in EVOO samples after a suitable liquid-liquid extraction procedure. The mean recovery values of the studied compounds ranged between 87 and 99%.

CE methods applied to the analysis of micronutrients in foods

This article reviews the applications of CE that are relevant to the analysis of small molecules in foods. CE has been applied to a wide range of important areas of food analysis and is rapidly being established as an alternative technique to chromatographic methods including HPLC and GC within analytical food and research laboratories. In recent years the analysis of food by CE has become more frequent and important and as such a variety of compounds have been separated and quantified. Although many other analytes have been detected by CE, this review will highlight areas relating primarily to the rather broad chemical classes of free amino acids, carbohydrates, organic acids, vitamins and a variety of antioxidants. In addition, information relating to the analyte, sample matrix, mode of CE employed, scope of the methodology and the detection and derivatization of the small molecules are considered and discussed.