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The purpose of this article was to investigate for the first time the nanoencapsulation of a naturally-occurring flavonoid, i.e. aureusidin, exhibiting a variety of properties including antioxidant. In particular, the encapsulation efficiency of aureusidin in biodegradable poly(lactic acid) PLA nanoparticles was evaluated using the emulsification-solvent evaporation technique, while some of the pertinent parameters affecting the properties of the formed nanoparticles were investigated. The obtained results were promising, suggesting that the particular polymer-technique system is a valid choice for aureusidin encapsulation and protection.

Grape seed extracts (GSEs) were investigated in yeast cells harbouring defects in their antioxidant system (regarding the cellular growth and growth recovery from H2O2 insult). GSEs antioxidant activity was detected in wild-type and mutant strains Δcta1, Δgsh1 and Δoye2glr1, while pro-oxidant activity in Δsod1 cells was seen. Assessment of proliferation of prostate cancer PC3 and HBV-replicating HepG2 2.2.15 cells treated with GSEs has shown higher cytotoxicity of red grape seed extract (RW) than white grape seed extract (WW) subjective to dose and period of administration. No antiviral effect was detected by measuring the secreted virion particles in HepG2 2.2.15 cells treated with GSEs. The GSEs play a dual antioxidant/pro-oxidant role in vivo according with the cellular antioxidant system deficiencies and exhibit cytotoxic properties in PC3 and HepG2 2.2.15 cell lines, but no antiviral action against HBV.

In this study, the behaviour of catechin (Cat) and ascorbic acid (AA) and their mixtures at different ratios was studied in view of elaborating predictions over an eventual pro-oxidant or synergistic antioxidant activity. The Co(II)–EDTA luminol chemiluminescence showed that the mixture of Cat:AA (3:1) had the highest antioxidant activity, while the mixture of Cat:AA (1:2) the most pronounced pro-oxidant activity. As the concentration of AA increases, the antioxidant behaviour of the mixture increases strongly as well. The LC–MS analysis for the two mixtures (Cat:AA at ratios of 1:2 and 1:3) revealed that the sufficient of AA accounts for the good antioxidant behaviour of catechin (Cat:AA 1:3 with an IC50 of 47.61 ± 0.00 μM and the mixture Cat:AA 1:2 with an IC50 of 75.32 ± 0.86 μM as assessed by chemiluminescence), supported by the formation of structure I (m/z 183). As its concentration decreases, the antioxidant activity drops and this is attributed to the formation of structure II (m/z 255). However, when AA becomes lesser beyond this point, a re-strengthening of the antioxidant behaviour has been observed, which may be assigned to the formation of procyanidin structures. Thus, AA may suppress the formation of procyanidin, i.e. creation of C C bonds between the catechin units.

In the present study the biocatalytic activity of a crude onion peroxidase extract on the reaction between catechol and heterocyclic 1,3-dicarbonyl compounds is investigated. The crude enzyme preparation promotes effectively the reaction between catechol and 4-hydroxycoumarin, 4-hydroxy-1-methyl-2-quinolinone and 2,4-quinolinediol to afford the corresponding coumestans and benzofuroquinolinones in satisfactory yields. The products of the reaction are fully characterized spectroscopically and are found to possess potent antioxidant activity as evaluated by 2,2-diphenyl-1-picrylhydrazyl (DPPH), ferric reducing antioxidant power (FRAP), and luminol-induced chemiluminescence assays.

The behaviour of four known antioxidants (quercetin, ascorbic acid, catechin and caffeic acid) and their mixtures at different molar ratios was studied in view of elaborating predictions over an eventual pro-oxidant or synergistic antioxidant activity. The Co(II)–EDTA luminol chemiluminescence showed that the mixture of quercetin and ascorbic acid at ratio 2:1 had the most pronounced antioxidant activity, while that of quercetin and caffeic acid at ratio 1:2 showed the least antioxidant activity, which may be interpreted as a strong propensity for pro-oxidant behaviour. The LC–MS analysis for the two mixtures revealed a significant amount of unoxidised quercetin in the case of quercetin with ascorbic acid, whereas in the case of quercetin with caffeic acid this amount was negligible. This observation supports the fact that the first combination was more antioxidant than the second, through efficient quercetin recycling (reduction of the quinone by ascorbic acid; redox cycling of quinones).

The ability of a crude onion peroxidase preparation to act as a biocatalyst for the oxidative dimerization–cyclization of methyl p-coumarate, methyl caffeate and methyl ferulate is presented. The products of the reaction have been fully characterized and were found to possess potent antioxidant activity in a ferric reducing antioxidant power (FRAP) assay.

The electrochemical behaviour and the antioxidant effectiveness of ascorbic acid (AA), caffeic acid (CA), quercetin (Q), catechin (Cat), hesperetin (H) and their equimolar binary mixtures were evaluated by means of cyclic voltammetry and luminol Co(II)–EDTA chemiluminescence, respectively, with a view to the prediction of a potential prooxidant or synergistic behaviour of mixtures of antioxidants. An important synergistic oxidation between Q and Cat was observed. The mixture CA/AA manifested the most prooxidant tendency among all the tested compounds and their mixtures. AA increased the antioxidant activity of Q and decreased that of Cat. Q and Cat regenerated CA, the prooxidant effect of the mixtures increasing with less e-delocalisation. Cat and CA have an antagonistic effect. H has the closest oxidation potential to CA and a slight increase of its antioxidant activity was registered when mixed with CA, which was not the case when it was combined with the other compounds or measured alone.

In the framework of the detailed phytochemical analysis of the aerial parts of Sideritis syriaca, two novel acylflavones were isolated together with three acetylated flavone glycosides and acylated flavone glycosides. The novel acylflavones were identified as isoscutellarein 7-trans-p-coumarate and apigenin 7-,4′-bis(trans-p-coumarate). Their structures were elucidated by means of UV, 1D and 2D NMR, LC–DAD–MS and confirmed by HR-MS spectroscopy.

Truffles are one of the most prized of foods but also one of the most perishable. Storing fresh truffles entails the use of low temperatures and the addition of carbon dioxide, but the effect of carbon dioxide on truffle metabolism is largely unknown. Treatment with 50% CO 2 + 5% O 2 at 2 °C for 29 d caused a reduction in polyphenol contents and antioxidant activity compared to the controls (air treatment). ADH (alcohol dehydrogenase) and LDH (lactate dehydrogenase) activities in CO 2 -treated samples decreased together with the related metabolites, ethanol and lactic acid, but on day 29 (final sampling) they increased again, reaching the initial levels but still below the concentrations of air-treated samples. Polyamine contents decreased initially in CO 2 -treated samples more than in air-treated truffles but at the final sampling increased significantly (1.5–2.3-fold). In summary, polyphenol metabolism, anerobic pathways, and polyamine biosynthesis are reduced by high CO 2 and low O 2 atmospheres, suggesting reduced general cell metabolic activity associated with reduced senescent activity, or stress effects. The rapid increase of polyamines and anaerobic metabolism could be an index of the reaction to stress only at the end of storage, and the increase in polyamines could provide protection against pathogen attack.

An experimental setup based on a 23-full factorial, central composite design was implemented with the aim to optimising recovery of polyphenols from onion solid wastes (OSW). In order to allow for the establishment of a sustainable process, reusable and non-toxic solutions composed of water/ethanol/citric acid were employed as extracting media. The factors considered were (i) the pH of the medium, (ii) the extraction time and (iii) the ethanol concentration. The model obtained produced a satisfactory fitting of the experimental data with regard to total polyphenol extraction (R2 = 0.97, p = 0.0025) and the reducing power of the extracts (R2 = 0.97, p = 0.0033), but not with the antiradical activity (R2 = 0.89, p = 0.0592). The 2nd order polynomial equations obtained after elaboration of the experimental data indicated that all parameters considered were significant in respect with the efficiency of total polyphenol recovery. The highest total polyphenol yield was theoretically predicted to be 9342 ± 1435 mg gallic acid equivalents per 100 g dry weight, under optimal conditions (60% EtOH, pH 2 and 4.2 h). Liquid chromatography-electrospray ionisation mass spectrometry of the optimally obtained extract revealed that the principal phytochemicals recovered were quercetin 3,4′-diglucoside, quercetin 4′-glucoside and quercetin. Simple linear regression analysis between the total polyphenol and the antiradical activity of the OSW extracts showed that there was no correlation in a statistically significant manner, as opposed to reducing power. Industrial relevance The recovery of value-added substances from agri-food industrial wastes is an issue with importance pertaining to both the reduction of the waste load released to the environment, and the development of novel, natural food additives with functional properties. Up to date, the examinations pertaining to the clarification of factors that can affect extractability were based on rather unilateral assessment, while it is generally accepted that the retrieval depends on several parameters, which render the phenomenon a particular complexity. In this view, the implementation of factorial design with respect to investigating in parallel several factors pertaining to efficient polyphenol recovery becomes imminent. Thus the establishment of models on such a sound experimental basis is expected to provide a reliable background for more costand resource-effective processes, with a potential direct industrial applicability.

Three procedures are developed and investigated for the simple and fast determination of peroxide value of olive oil by luminol chemiluminescence. The procedure using hemin as catalyst in carbonate alkaline solution allows the determination of hydrogen peroxide within the range 0.014–50 μM. The method can be used for the determination of peroxide value within the range 2.00–30.0 mequiv. O 2 /kg oil and results correlate very well ( r 2 = 0.99) with those of the official method. All reagents are aqueous solutions and olive oil is dissolved in acetone:ethanol mixed solution and, hence, the method is using minimal amounts of organic solvents and can be successfully applied to field analysis. Antioxidant activity of five common compounds found in natural products was determined by using luminol CL with Co(II) as EDTA complex as catalyst at pH 9.00.

The aim of this study is to enrich edible oils with carotenoids and lycopene from tomato puree or tomato peel, an industrial tomato waste. These tomato derivatives were incorporated in refined olive oil, extra virgin olive oil and refined sunflower oil. The incorporation of peel enhanced the concentration of β-carotene and lycopene more than tomato puree. Furthermore, the incorporation of both tomato puree and peel induced better thermal stability of the refined olive oil compared to extra virgin oil and sunflower oil. A decrease on total phenols as well as some prooxidant activity account for this, when tomato puree was incorporated. In our oil preparations, rutin and naringenin, as flavonoids coming exclusively from tomato puree or peel, were detected. The enrichment of oils with tomato carotenoids and lycopene, in particular low quality oils like refined olive oils, might be an alternative approach to elaborate new functional foods.

1. IntroductionModernbiocatalysisaimsat the development of novel,precisetools in the view of improving a wide range of processes, whichreduce energy and raw material consumption, and generate lesswaste and toxic side-products. Although putatively useful asbiocatalysts, the principal drawbacks hindering a broaderapplicability of enzymes are the high production cost and thelow yields obtained[1]. In recent years, the use of enzymes hasgained a wider acceptance, because of the recognition thatenzymes from various plant and microbial sources have severaladvantages over conventional physical and chemical treatmentprocesses. These advantages include selective removal of parti-cular pollutants, application to xenobiotic recalcitrant com-pounds, high reaction rates, operation over a wide range of pHand salinity, reduction in sludge volume, and simplicity ofcontrolling the process[2,3].Amongthe enzymicprocesses for waste treatment, peroxidase-and phenol oxidase-catalysed treatments of phenols and aromaticamines are probably the most comprehensively studied[4,5].Bacterial mono- and dioxygenases, reductases, dehalogenases,cytochrome P450, lignin- and manganese-peroxidases have beenemployed in a spectrum of bioremediation investigations[1,5].Peroxidases (peroxidase EC 1.11.1.7) are widely distributed innature. Most peroxidases are heme proteins and contain iron(III)protoporphyrin IX (ferriprotoporphyrin IX), as the prostheticgroup. The family of peroxidases comprises yeast cytochromecperoxidase, plant ascorbate peroxidases, fungal peroxidases andother classical plant peroxidases.Peroxidases catalyse the oxidation of a wide variety ofsubstrates, using H

The aim of this study was the detailed qualitative and quantitative analysis of the phenolic content of several extracts and fractions of Sorbus domestica fruits. The analysis was realized by LC–DAD–MS (ESI+). Twenty-four different extracts and fractions of five different maturity stages of the fruit were analyzed for comparison reasons in order to determine the most beneficial for health type of consuming. Sixty-two different phenolics were identified. There were significant qualitative and quantitative differentiations in the phenolic content among the different types of the fruits. All categories were rich in benzoic, phenylpropanoic and cinnamoylquinic acids and derivatives. Unripe fruit categories were also rich in flavonoids, while well matured fruit categories had a low content of flavonoids. Fruit pulp, which was proved to be a strong antioxidant according to previous research work, contained very low amounts of both acids and flavonoids, but its phenolic content was highly qualitatively differentiated from the other categories.

A hydroalcoholic medium at pH 3.5, containing Fe 3+ and pyruvic acid, was used as the model matrix to study quercetin/catechin interactions and their possible influence on the antioxidant characteristics of the system. Incubation at 55 � C for a period of 20 days resulted in a complete disappearance of quercetin and a decrease of catechin concentration by almost 75%. Liquid chromatography–mass spectrometry analysis showed that the degradation products are mainly quercetin derivatives, but evidence also indicated that there may be the formation of a co-pigment-like, decarboxylated pyruvic acid-bridged quercetin/catechin adduct. The hydroxyl free radical scavenging activity (SAHFR) exhibited significant negative correlation (P < 0.05) with both quercetin and catechin concentration whereas the antiradical activity (AAR) was positively and significantly (P < 0.05) linked only with quercetin, stressing its importance as natural antioxidant agent with a key role in food systems. � 2007 Elsevier Ltd. All rights reserved.

Quercetin was oxidized with potassium ferricyanide under alkaline conditions, a reaction that has been previously shown to generate the same set of products deriving from oxidation by mushroom polyphenol oxidase (PPO) and horseradish peroxidase (POD). The major oxidation product was isolated and characterized by means of 1H NMR and LC–MS, and it was found to be a quercetin heterodimer [1,3,11a-trihydroxy-9-(3,5,7-trihydroxy-4H-1-benzopyran-4-on-2-yl)-5a-(3,4-dihydroxyphenyl)-5,6,11-hexahydro-5,6,11-trioxanapthacene-12-one], occurring in onion skins. Its in vitro antioxidant properties were evaluated in comparison with the parent molecule and other natural polyphenols, employing three representative tests and the alterations in the activity observed were discussed on the basis of structure–activity relationships. Biomimetic chemical oxidations of natural polyphenols may help understand oxidation pathways in plant food commodities and evaluate the consequences on their nutritional value.

The aim of this study was to investigate the carotenoid composition and the provitamin A value of three palm date (Phoenix dactylifera) varieties (Deglet-Nour, Hamraya and Tantebouchte) from Algeria at three different ripening stages (khallal, rutab and tamr). Chromatographic analysis showed that the major carotenoid pigment present in dates is lutein followed by b-carotene, with an evident carotenoid disappearance during ripening from the khallal to the tamr stage. The different date fruits present a total carotenoid content in the range of 61.7–167, 32.6–672, and 37.3–773 lg/100 g fresh weight (FW) in Deglet-nour, Tantebouchte and Hamraya varieties, respectively. The rutab stage of Tantebouchte showed the lowest carotenoid content of 32.6 lg/100 g FW, whereas the khallal stage of Hamraya presented the highest value, 773 lg/100 g FW, followed by Tantebouchte with 672 lg/100 g FW. Provitamin A value (due exclusively to b-carotene) increased from 0.4 to 0.5 RE/100 g in Deglet-Nour fruits, but decreased from 11.7 to 1.6 RE/100 g and from 3.9 to 0.5 RE/100 g in Tantebouchte and Hamraya fruits, respectively, during ripening. The lowest value was found at the tamr stage of the Deglet-Nour variety (0.5 RE/100 g) whereas the highest provitamin A content was found at the khallal stage of the Tantebouchte variety (11.7 RE/100 g).

In the present work, thirteen algae from the Aegean Sea were examined for radical-scavenging activity (RSA) using the DPPH and chemiluminescence (CL) tests. Extracts of the brown alga Taonia atomaria exhibited the best RSA in comparison to the extracts of the other investigated species and approached the activity of powerful antioxidant standards. Column chromatography separation of T. atomaria extract, followed by preparative HPLC, resulted in the isolation of six metabolites, which were identified by spectral analyses (1H NMR, 13C NMR and MS). The isolated metabolites taondiol, isoepitaondiol, stypodiol, stypoldione, sargaquinone and sargaol were found to possess marked RSA.

Flavonols are one of the most studied classes of polyphenolic phytochemicals, because of the importance pertaining to their antioxidant potency and other biological activities. Grapes and grape products such as wine constitute an integral part of the human diet, and during the past few years several studies have generated analytical data on the flavonol profile, as well as on the factors that may affect it. To further aid epidemiological research, which is based on composition tables, this review aims at providing an up-to-date compilation of data on the flavonol composition of grapes and some of the principal commodities deriving from them, including grape juices and wines. Information regarding environmental and technological parameters that may influence flavonols in these products is also reported.

Thirty four different extracts, fractions and residues of five different maturity stages of the Greek Service tree fruits ( Sorbus domestica , fam. Rosaceae) were evaluated for their antioxidant activities (DPPH and luminol-induced chemiluminescence methods) and in correlation with their total phenolic contents (Folin–Ciocalteau test). Dichloromethane, diethyl ether and ethyl acetate fractions possessed significant radical-scavenging activities which were greater than the activity of trolox. This seemed to be correlated with their total phenolic content. Unripe yellow fruits, together with the fruit pulp, were the strongest antioxidants, while the well-matured brown fruits were the weakest ones. Results showed that the fractions of diethyl ether, ethyl acetate and dichloromethane, can be used as antioxidants in food and medicinal preparations.

The browning capacity of white wines was studied, employing an accelerated test and samples produced and stored under identical conditions. Browning was approached from a kinetic point of view and efforts were focussed on the investigation of plausible correlations with major redox-active polyphenols, including substances with an o -diphenol feature, such as gallic acid, caftaric acid, 2- S -glutathionylcaftaric acid (GRP), caffeic acid, catechin, and epicatechin. Over a period of ten days, browning development was shown to obey zero-order kinetics from the third day of the treatment, and browning rate constants ( k ) varied from 15.3 to 74.5 × 10 −3 day −1 . Regression analysis between k values and concentration of individual phenolics provided strong evidence that epicatechin is the principal browning agent ( r 2 = 0.8033, P P R ), throughout treatments, indicated that increases in browning are accompanied by a commensurate decline in the reducing ability, raising concerns about the impact of browning reactions on the in vitro antioxidant properties of white wines.

Caffeic acid (3,4-dihydroxycinnamic acid) was oxidized in wine-like model solutions (citrate buffer, pH 3.5) containing l -cysteine, by means of sodium periodate that mimics the mechanism of polyphenol oxidase (PPO). The reaction lead to the formation of a l -cysteine/caffeic acid adduct, which was isolated and tentatively identified as 2-S-cysteinylcaffeic acid (2-CCA), on the basis of LC-MS and 1H NMR data. The antioxidant properties of 2-CCA were assessed by employing the DPPH and a ferric-reducing test, and compared with both caffeic acid and l -cysteine, but also with gallic acid, which was used as a reference antioxidant. The results indicated that the adduct exhibits slightly improved antiradical activity in relation with the parent molecule (caffeic acid), but its reducing capacity was dramatically reduced, a fact that was theoretically ascribed to its strong chelating ability.

Summarization: A sensitive and simple procedure is described for determining the total phenolic/antioxidant levels of olive oil mill wastewater (OMW), using for the first time Co(II)/ethylenediaminetetracetic acid (EDTA)-induced luminol chemiluminescence. Olive oil wastewater samples were tested for their composition in simple phenolic compounds as a function of the extraction system (two- and three-phase centrifugation systems). The results revealed that the three-phase system had a stronger antioxidant activity and a higher total phenolic content than the twophase system. The relationship between antioxidant values and total phenolic content is also discussed. D 2004 Elsevier Ltd. All rights reserved. Παρουσιάστηκε στο: Environment international

The aim of this study was to determine the phenolic profile of seven different varieties of ripe date palm fruit (Phoenix dactylifera) from Algeria by LC–DAD–MS (ESI+), to investigate their respective antioxidant activities by the DPPH· method and to estimate their phenolic content using the Folin–Ciocalteu method. The total phenolic content was in the range of 2.49 ± 0.01 to 8.36 ± 0.60 mg gallic acid equivalents (GAE) per 100 g fresh fruit. This fruit was shown to possess an antioxidant activity, giving values of antiradical efficient (AE) from 0.08 ± 0.00 to 0.22 ± 0.00. The phenolic contents and the antiradical efficiencies of the different varieties were highly correlated (R2=0.975). All the varieties were found to contain mainly p-coumaric, ferulic and sinapic acids and some cinnamic acid derivatives. Three different isomers of 5-o-caffeoylshikimic acid were detected. Different types of flavonoids were identified, mainly flavones, flavanones and flavonol glycosides.

Tea and herbal infusions have been studied for their polyphenolic content, antioxidant activity and phenolic profile. The total phenolics recovered by ethyl acetate from the water extract, were determined by the Folin–Ciocalteu procedure and ranged from 88.1 ± 0.42 (Greek mountain tea) to 1216 ± 32.0 mg (Chinese green tea) GAE (Gallic acid equivalents)/cup. The antioxidant activity was evaluated by two methods, DPPH and chemiluminescence assays, using Trolox and quercetin as standards. The EC 50 of herbal extracts ranged from 0.151 ± 0.002 mg extract/mg DPPH (0.38 quercetin equivalents and 0.57 Trolox equivalents), for Chinese green tea, to 0.77 ± 0.012 mg extract/mg DPPH (0.08 quercetin equivalents and 0.13 Trolox equivalents), for Greek mountain tea. Chemiluminescence assay results showed that the IC 50 ranged from 0.17 ± 3.4 × 10 −3 μg extract/ml of the final solution in the measuring cell (1.89 quercetin and 5.89 Trolox equivalents) for Chinese green tea, to 1.10 ± 1.86 × 10 −2 g extract/ml of the final solution in the measuring cell (0.29 quercetin and 0.90 Trolox equivalents) for Greek mountain tea. The phenolic profile in the herbal infusions was investigated by LC-DAD-MS in the positive electrospray ionization (ESI + ) mode. About 60 different flavonoids, phenolic acids and their derivatives have been identified.

Ethyl acetate extracts of seeds originating from nine Hellenic native and international Vitis vinifera varieties cultivated in Greece were screened for their contents of characteristic polyphenols. The compounds determined were principal constituents of low molecular weight, including gallic acid (GA), catechin (CT), epicatechin (ECT), epigallocatechin (EGC), epicatechin gallate (ECG), epigallocatechin gallate (EGCG), and the procyanidins B 1 and B 2 (dimers). Total content varied from 55.1 to 964 mg per 100 g of seeds, the average being 380 mg per 100 g. The most abundant polyphenol was CT, accounting for 49.8% of the total content, followed by ECT (26.0%), ECG (9.3%), procyanidin B 1 (5.8%), and procyanidin B 2 (5.1%), whereas EGC and GA were minor constituents. The assessment of the in vitro antiradical activity ( A AR ), employing the stable radical DPPH , showed that there is a significant correlation with total polyphenol content ( r 2 =0.6499, P 1 may be one of the most important radical scavengers in grape seed extracts ( r 2 =0.7934, P

14 pages, 7 figures, 3 tables., Kinetic studies on thermal stability of anthocyanins isolated from the dry calyces of Hibiscus sabdariffa L. (roselle) were carried out in aqueous solutions (55–98 °C), either as free or copigmented anthocyanins with chlorogenic acid, and in the dry state as free anthocyanins or co-lyophilized with an amorphous polysaccharide (pullulan) and stored in different relative humidity environments (water activities 0.33, 0.53, 0.75 and 0.84) at 40 °C. The rate constants for degradation were obtained from first-order reaction kinetic plots. The degradation kinetics of individual anthocyanin components in solution, as assessed by HPLC, followed an Arrhenius-type response with respect to temperature; activation energies, Ea, varied between 13.3 and 15.1 kcal/mol. Copigmentation of anthocyanins with chlorogenic acid did not seem to improve their stability in solution. In the dry state, the degradation rate constants increased with the water activity, particularly above 0.53. In the freeze-dried pullulan–anthocyanin mixtures, the polysaccharide matrix delayed colour degradation compared to the free anthocyanin preparations by 1.5–1.8 times. The degradation kinetics of anthocyanins did not show any dependence on the molecular mobility of the system, as it relates to the glass–rubber transition (Tg) detectable by calorimetry. Anthocyanin degradation occurred, even at sub-Tg temperatures of the amorphous matrices, whereas no changes in the rate constants were observed in the vicinity of the glass transition; the plot of (lnk)−1 against (T−Tg) was linear with all data fitting into a common line as predicted by the Williams–Landel–Ferry (WLF) equation. Both free and co-lyophilized with pullulan Hibiscus anthocyanins exhibited good antiradical activity throughout storage in all humidity environments studied, despite of a substantial loss in colour intensity., G.G. acknowledges the receipt of a fellowship from MAICh during her MSc studies. This project has been partially supported from the GreekM inistry of Industry, Energy and Technology and the Spanish Ministerio de Asuntos Exteriores through a grant of bilateral cooperation between Greece and Spain.

Twenty-six white wines of “Appellation of Origin of High Quality”, covering all viticultural areas of Greece were assayed for their polyphenolic content, using high-performance liquid chromatography coupled with diode array detector. Further, the antiradical activity and reducing power of the wines were evaluated. In both cases, the antioxidant potency of the wines was correlated with the total polyphenol concentration, as well as with the concentration of the two major classes of white wine polyphenols, hydroxycinnamates and flavanols. It was found that wines contain in average 324.7 mg l −1 total hydroxycinnamates (THC) and 52.2 mg l −1 total non-hydroxycinnamates (TNHC), (catechin, epicatechin, gallic acid). The antiradical activity was correlated principally with total phenols (THC+TNHC) and with THC, but poorly with TNHC. By contrast, TNHC were found to exert sound reducing effect, as opposed to THC which were weakly correlated with the reducing power.

Selected Greek regional, aged red wines were assessed for their polyphenolic composition using well-established spectrophotometric methodology, and tested for antioxidant potential by three different assays. The total polyphenol (TP) concentration was found to vary from 1217 to 3772 mg L −1 gallic acid equivalents, total anthocyanin (TA) content ranged from 44.3 to 360.1 mg L −1 , and total flavanol (TF) from 291.1 to 664.8 mg L −1 catechin equivalents. The antiradical activity was evaluated using DPPH • , and varied from 0.73 to 1.37 m M Trolox® equivalents, while reducing power values were from 5.29 to 10.80 m M ascorbic acid equivalents, using a modified FRAP assay. The hydroxyl free radical scavenging activity was determined with the deoxyribose method, and ranged from 38.5 to 59.9% decrease in A 532 relative to control. The examinations showed that TP and TF may provide a significant contribution to the overall antioxidant status of wines, but TA appears to be a less important factor in this respect. Reducing power was found to be highly associated with the antiradical activity of wines.

The effect of irrigation and harvest time was studied with respect to almond kernel quality with two almond cultivars. Kernel quality analyses included kernel weight, moisture content, kernel oil quality and composition, and sugar content and composition. ‘Ferragnes’ kernels had similar oil content and quality but higher oleic acid content than ‘Texas’ almonds. Various differences were also found in sugar content and composition between the two cultivars. Irrigation delayed almond maturation, had no effect on oil and sugar content, but improved oil composition with higher oleic acid content and sugar composition with higher sucrose content compared to dry-grown almonds. Late harvested almonds contained more dry matter per kernel, higher oil content but of lower quality, based on the UV absorption coefficients and oil composition, and higher sugar content mainly due to further sucrose accumulation compared to early harvested almonds.

A simple, rapid, sensitive, and enzyme-free analytical method for estimating scavenging of hydrogen peroxide (H2O2) was developed.Peroxyoxalate chemiluminescence (POCL) was measured, using 9,10-diphenylanthracene as fluorophore.The chemiluminescence signal was found to be linear in response to increasing amounts of H2O2 in ethyl acetate/acetonitrile (9:1) (r2 = .9990), within a range of concentrations varying from 9.0 to 72.0 microM. In contrast, acetonitrile was highly unsuitable because of poor linearity (r2 = .3736) and poor signal stability. The linearity of POCL inhibition, as a measure of H2O2 scavenging, was tested employing well-known, lipid-soluble antioxidants, including beta-carotene, butylated hydroxytoluene (BHT) and alpha-tocopherol, and also the more polar flavonol quercetin, and the water-soluble L-ascorbic acid (AA). Under the experimental conditions, the corresponding values of H2O2 scavenging activity (SA(HP)) for quercetin, beta-carotene, alpha-tocopherol, and L-AA were 19.1 +/- 0.4, 70.9 +/- 20.1, 8.4 +/- 0.4, and 44.8 +/- 5.6 x 10(-3) microM(-1)The data establish the assay as a method for assessing the H2O2 quenching activity of lipid-soluble antioxidants.

A rapid and sensitive method has been developed for the determination of trans -resveratrol in wine. This method consists of a solid phase extraction step followed by a rapid HPLC quantification step (30 min). The improvement of this method consists of the washing step of the solid phase extraction method carried out at pH 8.0 (12% ethanol in a phosphate buffer solution), thus permitting a more efficient removal of the interfering phenolic compounds in conjunction with the required low volume of tested sample. Trans -resveratrol content was determined for 29 red Greek wines of appellation of origin. The concentrations found varied between 0.550 and 2.534 mg/l. The wines produced by grape varieties grown in the Greek islands (Rhodes, Crete and Paros) were richer in trans -resveratrol. The grape variety Mandilaria, in particular, was the Greek variety with the highest trans -resveratrol content.

Wine is one of the most important products of Greece and other Mediterranean countries. Adulteration of wines, either in terms of geographical origin or variety, has been a major topic of debate and extensive research. Various instrumental methods (gas chromatography, high pressure liquid chromatography) and sensory analysis, in conjunction with statistical analysis, were developed and applied in an attempt to provide reliable answers to this issue. This research aimed at classifying 33 greek wines from various regions by employing both instrumental and sensory analysis. Application of principal component analysis (PCA) to our experimental data resulted in satisfactory classifications of only Greek red wines in terms of their geographical origin. Greek wines were effectively distinguished in two or three groups (depending on PCA figure); wines from Aegean/Ionean islands. North Greece and South Greece. However, further work with greater numbers of samples is required in order to draw more valid conclusions and to obtain a detailed map of greek wines according to their geographical origin and variety.

The potential of a crude peroxidase (POD) from onion solid waste as a biocatalyst for the synthesis of a naturally occurring aurone is described. The crude enzyme preparation effectively promotes the cyclization of 2′,3,4,4′,6′-pentahydroxy-chalcone (which is not a natural substrate of onion POD) into aureusidin.

The scavenging activities of three standard antioxidants, quercetin, ascorbic acid, and trolox, were evaluated by Co(II)/ethylenediamine-tetraacetic acid (EDTA)-induced luminol chemiluminescence and the 2,2-diphenyl-1-picrylhydrazyl (DPPH*) free radical assay. Therefore, the aim of this study was to characterise an enzyme-free and time-independent chemiluminescence method for the assessment of the scavenging profile of compounds in a cell-free system using the Co(II)/EDTA-luminol-peroxide system. These results showed that the three standards were efficient and effective in inhibiting both Co(II)/EDTA-induced luminol chemiluminescence and the free radical DPPH*. For all the data obtained in this work, the scavenging activity for the standards tested decreased in the following order: quercetin > trolox > ascorbic acid. The present study has applied a simple and precise procedure for the study of hydroxyl radical scavenging activity by Co(II)/EDTA-induced luminol chemiluminescence, and this was assessed by DPPH* free radical scavenging.

Hexane extracts obtained by percolation from the leaves of nine Mediterranean plants ( Daphne oleoides , Myrtus communis , Pelargonium zonale , Phillyrea latifolia , Pistacia terebinthus , Quercus pubescens , Rhamnus lucioides , Sideritis syriaca , Smilax aspera ) and from five leaf spices ( Rosmarinum officinalis , Coridothymus capitatus , Laurus nobilis , Salvia fruticosa , Salvia pomifera ) were examined for the presence of tocopherols by thin layer chromatography, gas chromatography, high performance liquid chromatography and combined gas chromatography–mass spectrometry. With the exception of Sideritis syriaca , in all the plants and spices examined α-tocopherol was found to be present. The β - and γ -homologues were detected only in the extracts of Pelargonium zonale and Smilax aspera . Quantitative analysis by HPLC gave values ranging from 250 to 1325 ppm total tocopherols (on a dry leaf basis). These values are higher than those reported for oil seeds (sunflower seed, cottonseed, rapeseed, sesame seed) or other oil sources (peanut, soybean, maize).

A method is described for the evaluation of the peroxide value (PV, meq. O 2 kg −1 ) in olive oil. The method is based on the chemiluminogenic energy-transfer reaction of bis(2,4,6-(trichlorophenyl)oxalate (TCPO) with hydrogen peroxide or total peroxides in the presence of Mn(II) as catalyst and 9,10-dimethylanthracene as fluorophore. The procedure developed allows the evaluation of PV within the range of 0.6–100 meq. O 2 kg −1 (CL intensity = 1.76 × PV (meq. O 2 kg −1 ) + 23.2, r 2 = 0.994, n = 9) and relative standard deviation within the range 1–5% by using a simple manual measurement.

Hetero Diels-Alder reaction of diene 10 , obtained in one step from aldehyde 4 , with nitroso dienophile 6 produced the dihydro-2H-1,2-oxazines 12 . Treatment of the tosylates 13 derived from 12 with TBAF induced a ring contraction process leading directly to pyrrole 16 . Cyclization of this intermediate furnished the pyrrolo-castanospermine derivative 17 .