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The present study aimed to optimize the recovery of bound phenolic antioxidants from rice hulls via microwave-assisted alkaline hydrolysis using response surface methodology. The microwave treatment duration, temperature, and solvent:solid ratio were the independent variables selected; whereas total phenol content, antioxidant activity (DPPH●, ABTS●+, CUPRAC assays), and the p-coumaric and ferulic acids concentration were the dependent ones. The optimum conditions were found to be 3.6 min, 155 °C, and 50:1 v/w which were then applied to hulls from different rice varieties cultivated in Greece [Gladio, Krezo, Scirocco, Karolina (two samples), Europa, Bravo, Bella (parboiled), and Fino (long-grain rice)]. The results were compared to those obtained using an optimized ultrasound-assisted alkaline hydrolysis protocol (120 min, 80 °C, 50:1 v/w) proposed in the literature. The values obtained with microwaves were much higher compared to those obtained by ultrasounds (i.e., p-coumaric acid levels were 1.2 to 2.2-fold higher, and those of ferulic acid were 2.1 to 6.0-fold higher) using almost 2-fold higher temperature but reducing the hydrolysis duration by ~33-fold. Thus, the optimized approach may assist the valorization of rice hulls as a sustainable source of natural phenolic antioxidants for novel food applications.

Essential oils (EOs) find application as flavoring agents in the food industry and are also desirable ingredients as they possess preservative properties. The Mediterranean diet involves the use of a lot of herbs and spices and their products (infusions, EOs) as condiments and for the preservation of foods. Application of EOs has the advantage of homogeneous dispersion in comparison with dry leaf use in small pieces or powder. Among them

The pan-European distributed Research Infrastructure for Promoting Metrology in Food and Nutrition (METROFOOD-RI) has evolved in the frame of the European Strategy Forum on Research Infrastructures (ESFRI) to promote high-quality metrology services across the food chain. The METROFOOD-RI comprises physical facilities and electronic facilities. The former includes Reference Material plants and analytical laboratories (the ‘Metro’ side) and also experimental fields/farms, processing/storage plants and kitchen-labs (the ‘Food’ side). The RI is currently prepared to apply for receiving the European Research Infrastructure Consortium (ERIC) legal status and is organised to fulfil the requirements for operation at the national, European Union (EU) and international level. In this view, the METROFOOD-RI partners have recently reviewed the scientific plan and elaborated strategic priorities on key thematic areas of research in the food and nutrition domain to which they have expertise to contribute to meet global societal challenges and face unexpected emergencies. The present review summarises the methodology and main outcomes of the research study that helped to identify the key thematic areas from a metrological standpoint, to articulate critical and emerging issues and demands and to structure how the integrated facilities of the RI can operate in the first five years of operation as ERIC.

In the present work, the role of the carboxyl group of o-dihydroxybenzoic acids (pyrocatechuic, 2,3-diOH-BA and protocatechuic, 3,4-diOH-BA) on the protection against induced oxidative stress in Saccharomyces cerevisiae was examined. Catechol (3,4-diOH-B) was included for comparison. Cell survival, antioxidant enzyme activities, and TBARS level were used to evaluate the efficiency upon the stress induced by H2O2 or cumene hydroperoxide. Theoretical calculation of atomic charge values, dipole moment, and a set of indices relevant to the redox properties of the compounds was also carried out in the liquid phase (water). Irrespective of the oxidant used, 2,3-diOH-BA required by far the lowest concentration (3–5 μM) to facilitate cell survival. The two acids did not activate catalase but reduced superoxide dismutase activity (3,4-diOH-BA>2,3-diOH-BA). TBARS assay showed an antioxidant effect only when H2O2 was used; equal activity for the two acids and inferior to that of 3,4-diOH B. Overall, theoretical and experimental findings suggest that the 2,3-diOH-BA high activity should be governed by metal chelation. In the case of 3,4-diOH BA, radical scavenging increases, and chelation capacity decreases. The lack of carboxyl moiety (3,4-diOH B) improves to radical scavenging, interaction with lipophilic free radicals, and antioxidant enzymes. The present study adds to our knowledge of the antioxidant mechanism of dietary phenols in biological systems.

Density functional theory/Becke’s three-parameter hybrid functional combined with the Lee–Yang–Parr correlation functional (DFT/B3LYP) was used to examine the radical scavenging potential of resveratrol, piceatannol, and their dehydro/dihydro counterparts. For this reason, the values of molecular descriptors predicting the hydrogen atom transfer (HAT) and the single electron transfer preceding (SET-PT) or following a proton transfer (SPLET) were computed in the gas and liquid (benzene, water) phases. The double bond, resulting in molecular planarity, was predicted to favor the single hydrogen or electron transfer. The triple bond, resulting in a linear backbone, was predicted to decrease the ease of these transfers, whereas the saturation, resulting in loss of planarity, was expected to decrease the activity even more. The impact of saturation was predicted to be detrimental for resveratrol. However, for piceatannol, an enhancement of activity was proposed only under stepwise HAT because allylic hydrogen ...

A set of seven commercial white wine samples (W1–7) produced from the cultivar Malagousia and obtained directly from the cellar 4 months after winemaking were subjected to accelerated oxidation (55 °C, 11 days). The correlation of browning susceptibility with compositional data, as well as the effect on phenolic content using simple assays, and the radical scavenging activity (DPPH·, ABTS·+) were examined. Calculated browning rate constants (k) varied by 1.03–2.66-fold among pairs of samples. Thus, despite the fact that samples originated from the same cultivar, differences were significant in some cases. No correlation was observed between browning and total or free sulfur dioxide, total iron, copper or other compositional parameters (total phenol, total hydroxycinnamates, total flavanol, catechin, epicatechin content, etc.), except for the grape reaction product/caftaric acid ratio (0.802, p = 0.017). The later suggested that wine must elaboration might be important for white wine oxidative stability, and its contact with oxygen should be avoided or minimized. Addition of ascorbic acid at the maximum level detected in the tested wines (70 mg/L), to one of the samples free of ascorbic acid but containing the highest level of total (100 mg/L) and free SO2 (30 mg/L) among these, had a negative effect. However, one of the samples containing ascorbic acid (33 mg/L) was resistant to oxidation. The molar ratio of free SO2 to that of ascorbic may affect browning susceptibility; therefore, the use of ascorbic acid should be made with caution. Chemometrics could be useful to provide prediction of browning susceptibility in relation to compositional data. The radical scavenging activity decreased with a significant correlation between the loss in DPPH· scavenging and ascorbic acid content (r = 0.845, p = 0.008). The changes in total flavanols did not follow a clear trend, whereas the spectrophotometric monitoring of total hydroxycinnamate was not informative due to interferences with browning products. Present findings are expected to be useful for those involved in white wine production.

The generalized two-dimensional correlation spectroscopy (g2D-COR spectroscopy) analysis combined with its extended version moving-window 2D-COR (MW-2D-COR) was performed on a set of kinetic ATR-FTIR spectral data. The former is a mathematical method that is applied to a set of spectra collected for a sample exposed to an external perturbation (e.g. storage time). Virgin olive oils (VOOs) of similar fatty acid composition, chlorophyll, and a-tocopherol content were photooxidized (10,912 Lx, no headspace, 24 h). The proposed approach revealed hidden information under specific ATR-FTIR bands and the order of events was established using appropriate rules. MW-2D-COR analysis displayed the evolution of changes during storage. In this way, the detection of the time interval upon which spectral changes are observed was evidenced. As an overview, MW plots of the analyzed samples revealed three time-zones in which changes tend to maximize, with the first one to reach a peak at ~2.5 h. The area around 2850-2930 cm−1 including bands assigned to the symmetric and asymmetric stretching vibration of the aliphatic –CH2- bonds, was the one found to be affected in all VOOs. The time interval upon which spectral changes are first detected in the corresponding area could serve as an index for the commencement of the loss of freshness. Present findings highlight the need to combine the two types of correlation analyses to obtain meaningful information on VOO photooxidation kinetics. Lipid scientists may gain an extra tool in their efforts to understand oxidation phenomena.

Metabolomics involvement in the study of foods is steadily growing. Such a rise is a consequence of the increasing demand in the food sector to address challenges regarding the issues of food safety, quality, and authenticity in a more comprehensive way. Virgin olive oil (VOO) is a key product of the Mediterranean diet, with a globalized consumer interest as it may be associated with various nutritional and health benefits. Despite the strict legislation to protect this high added-value agricultural commodity and offer guarantees to consumers and honest producers, there are still analytical issues needing to be further addressed. Thus, this review aims to present the efforts made using targeted and untargeted metabolomics approaches, namely nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry-based techniques (mainly LC/GC-MS) combined with multivariate statistical analysis. Case-studies focusing on geographical/varietal classification and detection of adulteration are discussed with regards to the identification of possible markers. The advantages and limitations of each of the aforementioned techniques applied to VOO analysis are also highlighted.

&Tau, oward a harmonized and standardized procedure for the determination of total hydroxytyrosol and tyrosol content in virgin olive oil (VOO), the pros of a recently published in house validated ultra high performance liquid chromatography (UHPLC) protocol are discussed comparatively with those of other procedures that determine directly or indirectly the compounds hosted under the health claim on &ldquo, olive oil polyphenols&rdquo, (EC regulation 432/2012). Authentic VOOs were analyzed with five different liquid chromatographic separation protocols and 1H-NMR one in five different laboratories with expertise in VOO phenol analysis within three months. Data comparison indicated differences in absolute values. Method comparison using appropriate tools (Passing-Bablok regression and Bland Altman analyses) for all protocols vs. the UHPLC one indicated slight or statistically significant differences. The results were also discussed in terms of cost effectiveness, detection means, standard requirements and ways to calculate the total hydroxytyrosol and tyrosol content. Findings point out that the in-house validated fit for the purpose UHPLC protocol presents certain pros that should be exploited by the interested parties. These are the simplicity of sample preparation, fast elution time that increase the number of samples analyzed per day and integration of well-resolved peaks with the aid of only two commercially available external standards. Importance of correction factors in the calculations is stressed.

The present work aimed at examining the combined effect of chlorophyll content and light filtering packaging material on the photo-stability of virgin olive oil (VOO) via mesh cell-FTIR spectroscopy monitoring. Four different VOOs of Koroneiki cultivar differing in total chlorophyll content (∼12–46 mg/kg) were exposed in parallel to direct visible light (6000 lx, 24 °C, 344 h) and FTIR spectra were recorded periodically with or without applying light protection by an industrial filter used for packaging. Findings suggested that the protective role of light filtering material was more evident in the VOO with the lowest total chlorophyll content. Real time monitoring of VOO by mesh cell-FTIR was found to be a useful tool to follow the combined effect of pro-oxidant chlorophylls and the protective light filtering materials on the photo-oxidation process of VOO employing a minute sample amount., Financial support by Fundación General CSIC (Programa ComFuturo) is acknowledged. This work was also supported by Spanish State Secretariat of Research, Development and Innovation (AGL2015‐69320-R project). DT received funding for an Erasmus + Internship.

DFT calculation of various molecular descriptors was carried out in order to examine the radical scavenging properties of sesame oil lignans and some selected metabolites of sesamin formed in vivo. The major sesame oil lignans, namely sesamin and sesamolin may present antioxidant activity through hydrogen atom transfer, though lacking a phenolic group. This can be achieved via the contribution of allylic hydrogen atoms according to C–H bond dissociation enthalpy (BDE) values. Even so, the predicted activity is not higher than that of some phenolic derivatives (e.g. pinoresinol) or metabolites bearing catechol moieties. The contribution of non-phenolic hydrogen atoms may result in the formation of planar or semi-planar conjugated compounds. Some of the tested lignans (e.g. sesaminol, sesamolinol) may be efficient electron donors comparable to active flavonoids according to ionization potential (IP) values. Neutral sesamol can be an efficient electron donor rather than hydrogen atom donor according to IP and net electrophilicity values. Only computation in water could partially justify literature experimental findings on the higher reactivity of sesamol over that of sesamin. The metabolites of sesamin, bearing one or two catechol groups were found as the most efficient hydrogen atom donors and most prone to ionization. Therefore, they could be capable to act efficiently via hydrogen atom transfer (HAT) or sequential proton loss electron transfer (SPLET) in real systems as shown by gas-phase and calculations in solvents (benzene, water). Thus, these metabolites may account for the high in vivo antioxidant activity of sesamin. Examination of the succeeding products of metabolism indicated the progressive loss of radical scavenging efficiency which was predicted to be negligible in the compounds excreted from the body of mammals.

Hydroxytyrosol (HT) and a set of synthetic isochroman derivatives of HT have been studied with regards to their radical scavenging activity in the gas employing density functional theory (DFT) and the Becke's 3 Lee Yang Parr (B3LYP) functional. Values of molecular descriptors (bond dissociation enthalpy, BDE; ionization potential, IP; proton dissociation enthalpy, PDE; proton affinity, PA; electron transfer energy, ETE; electron accepting power, ɷ +; electron donating power, ɷ −; net electrophilicity, Δɷ±) characterizing the hydrogen atom or electron donating efficiency of test compounds were used. Published experimental findings for the radical scavenging activity of the same compounds using methods such as Rancimat, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) radical cation and oxygen radical absorbance capacity were discussed. All the synthetic isochromans were predicted to be more potent hydrogen atom and electron donors than HT, though polarity may affect their performance in lipidic systems. Present findings point out that HT and examined isochromans prefer to scavenge free radicals via hydrogen atom transfer instead of electron donation and that allylic hydrogen atoms are expected to account for a higher activity in comparison to other phenolic antioxidants. The most potent hydrogen atom donor was the one bearing two catechol groups which can form stepwise a di-quinone and then scavenge additional radicals via allylic hydrogen atom donation and subsequent adduct formation. The total enthalpy required for all hydrogen atoms donated by test compounds was the most appropriate index of experimental activity prediction instead of common descriptors.

4 Tablas.-- 4 Figuras, The determination of the total hydroxytyrosol (Htyr) and tyrosol (Tyr) content of virgin olive oil is of utmost interest for the International Olive Council (IOC), food authorities, producers, and distributors after the issuing of a health claim that “olive oil polyphenols contribute to the protection of blood lipids from oxidative stress.” To address the need of a harmonized and standardized protocol the present study focuses on the extraction solvent of the polar fraction. Aqueous mixtures of methanol and acetonitrile of equal polarity are prepared and comparatively examined. Different analytical approaches (Folin-Ciocalteu assay, reversed phase chromatography-diode array-fluorescence detection, LC-Orbitrap, LC-TOF, LC-TQd, H-NMR) are applied to highlight the extracting efficiency of the tested mixtures regarding the phenolic content and composition. The use of acetonitrile does not have a clear positive effect that could compensate its higher cost, commercial availability, and toxicity. The findings justify further why methanol:water, 80:20 v/v should be retained in a future IOC protocol for the accurate and repeatable determination of total Htyr and Tyr content, which is necessary to support the health claim for “olive oil polyphenols.”. Practical Applications: The development of a harmonized and standardized methodology for the determination of total Htyr and Tyr content in an explicit manner is a request of the olive oil sector. A tool that can be introduced easily in the olive industry and official laboratories for the control of the label that bears a health claim for “olive oil polyphenols,” is also requested by the consumers and the IOC. In this view, the present study contributes to the cornerstone that is the standardization of the extraction solvent. Methanol:water 80:20 v/v, should be retained in an International Olive Council protocol for the accurate and repeatable determination of total hydroxytyrosol and tyrosol content necessary to support the health claim for “olive oil polyphenols”. If the total hydroxytyrosol and tyrosol content is determined after hydrolysis of the polar fraction no effect of artifact formation in the quantitation should be expected., H2020 Societal Challenges. Grant Number: 635690

2 Figuras.-- 3 Tablas, The viewpoint is the outcome of the scientific expertise of the scientists that sign it and work collaboratively in the frame of the OLEUM project. The project aims to better guarantee olive oil quality and authenticity by empowering detection and fostering prevention of olive oil fraud and by an effort of harmonization, correct interpretation, and use of official and supporting analytical methods. Practical Applications: The consensus among scientists, the European food authorities, IOC, and the olive industry on which compounds should be determined to support the health claim on olive oil polyphenols (EC Reg. 432/2012) is of utmost importance and can be supported by the evidence provided in this viewpoint article. The exact interpretation of this health claim involves the clarification of the compounds that should be summed up to give the amount of at least 5 mg phenols per 20 g of oil., H2020 Societal Challenges. Grant Number: 635690

This paper describes the development of an image processing algorithm, which can estimate the amount of adulteration of olive oil with soybean oil from a captured photo. This algorithm is intended to be implemented into an application for modern smartphones, where the user can measure the quality of a sample of olive oil, only by taking photos from the sample. The determination of the adulteration percentage is done by separating the captured image into two regions: one that contains only the oil sample and another one, which contains the rest of the image. The colour difference between these two regions, for known adulteration percentages is used to determine the appropriate model that combines these quantities. Then, any other mixture of these oils, can be identified using the derived model and the methodology that is described in this paper.

The phenolic content/composition and antioxidant activity of hot/cold infusion and decoction from the leaves of Arbutus unedo were studied for the first time. 1,1-diphenyl-2-picrylhydrazyl (DPPH●), 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) radical cation (ABTS●+), crocin-bleaching, copper-reducing, and liposome accelerated oxidation assays were used for the evaluation of the activity in vitro. In vivo, the extracts were examined for their ability to protect S. cerevisiae cells from H2O2 induced oxidative stress. An on-line high-performance liquid chromatography-DPPH● assay was applied to identify potent radical scavengers and comment on their contribution to the total activity. The addition of leaves to boiling water (decoction) was the most appropriate practice to apply since the highest phenol intake (220.2 mg gallic acid/cup served) was obtained. Additionally, its antioxidant activity was equal or superior to that of the other extracts. Flavonols (~51–61 mg/g dry extract) were the main phenols in all the extracts, with quercitrin accounting for ~20% of the total phenol amount. The on-line DPPH● method verified the high potency of the decoction and indicated as the most active radical scavengers, two galloylquinic acid derivatives and myricitrin, accounting for ~28–45% and ~11–13% of the total scavenging, respectively. Present data may contribute to the future exploitation of A. unedo leaves by the food industry for health-promoting herbal tea preparations and dietary supplements.

Food by-products and waste valorisation practices have gained much attention lately as a means of a sustainable management, which can concomitantly increase the profit for local economies. So far, these materials constitute an underexploited source for the recovery/production of compounds for food applications and other needs of the food chain (energy production, feeds). To highlight new trends and show the potential for regional economies the present contribution focuses on Central Macedonia, the largest Greek region with significant agro-industrial activities, such as olive oil, wine and rice production, that generate different types and quantities of by-products and waste. Proposals for the exploitation of selective streams using chemical and biotechnological tools for the recovery/production of compounds of high interest for the food industry are critically discussed. Know-how developed by academia and research institutions in the Central Macedonia should be examined by the respective stakeholders in order to contribute to the zero-waste society target set by European Union till 2025.

Seven commercial white wine samples of the Malagousia cultivar were investigated for the first time with regard to their phenolic composition and radical scavenging activity. Total phenol content, corrected for ascorbic acid contribution (0–47 mg gallic acid equivalents/L of wine), ranged between 241 and 336 mg gallic acid equivalents/L of wine. On the other hand, the range for total hydroxycinnamates was 51.5–122.4 mg chlorogenic acid equivalents/L of wine and that for total flavanols 19.6–68.8 mg catechin equivalents/L wine. Fifteen phenolic compounds were identified and quantified by gas chromatography/mass spectrometry in the selective ion monitoring and high-performance liquid chromatography coupled with diode array detector. Tyrosol, caftaric, caffeic and 2-S-glutathionyl caffeoyl tartaric (GRP) acids were the major phenolics in all samples with mean concentrations of 12.32, 10.71, 10.17 and 4.79 mg/L wine, respectively. Catechin (3.75 mg/L) and p -coumaric acid (3.04 mg/L) followed in abundance. Variations in the values of GRP/caftaric (0.1–4.6) and caffeic/caftaric (0.4–4.2) acid concentrations, suggested differences in the degree of oxidation on one hand and hydrolytic processes during production and bottling on the other. Despite these variations, the radical scavenging activity of samples examined with DPPH and ABTS + assays (mean value 0.85 and 3.45 mmol Trolox equivalents/L of wine) indicated a high efficiency in comparison to literature data on native and foreign white wines. The present findings can be useful for both technological and nutritional purposes.

The impact of alkaline or acid digestion to phenolic content (TPP), antioxidant activity (radical scavenging, copper (II) reducing and liposome oxidation) and phenolic composition of rice hull extracts was evaluated systematically for the first time. Alkaline digestion yielded extracts superior in TPP (13206-25498 mg gallic acid/kg dry hulls) and antioxidant activity. Chromatographic analysis showed that these were rich in hydroxycinnamic acids, whereas hydroxybenzoic acid/aldehyde derivatives, obtained as hydroxycinnamate degradation products, were the main phenolics in the extracts after acid treatment. Optimized alkaline digestion (120 °C, 120 kPa, 2 h) applied to hulls from selected rice varieties cultivated in Greece, showed a high p-coumaric (4879–6367 mg/kg dry hulls) and ferulic acid (1510–2037 mg/kg dry hulls) content, probably related to their low silicon levels (44,916–59,981 mg SiO2/kg dry hulls). Our study provides useful data for exploitation of rice hulls by the food industry.

Density functional theory/Becke's three-parameter hybrid functional combined with the Lee-Yang-Parr correlation functional (DFT/B3LYP) was used to examine the radical scavenging potential of resveratrol, piceatannol, and their dehydro/dihydro counterparts. For this reason, the values of molecular descriptors predicting the hydrogen atom transfer (HAT) and the single electron transfer preceding (SET-PT) or following a proton transfer (SPLET) were computed in the gas and liquid (benzene, water) phases. The double bond, resulting in molecular planarity, was predicted to favor the single hydrogen or electron transfer. The triple bond, resulting in a linear backbone, was predicted to decrease the ease of these transfers, whereas the saturation, resulting in loss of planarity, was expected to decrease the activity even more. The impact of saturation was predicted to be detrimental for resveratrol. However, for piceatannol, an enhancement of activity was proposed only under stepwise HAT because allylic hydrogen atoms could be prone for abstraction after the formation of quinone. The predictions (gas, liquid phase) were in agreement with experimental evidence for resveratrol and its derivatives. The lipophilicity, which may affect antioxidant activity in real systems, increased according to partition coefficient (log P) values as follows: dihydrostilbenestilbenedehydrostilbene. On the basis of dipole moment values, no clear trend was observed.

The applicability of FT-MIR/ATR spectroscopy (4000–400 cm−1) for the evaluation of early stages of autoxidation was examined for extra virgin olive oil samples (EVOO), which even after 12-month storage (dark, 23 ± 3°C) satisfied official limits for acidity, peroxide, K232 and K270 values. Changes in intensity values at 3470 cm−1 (hydroperoxide formation) and in values of various intensity ratios, namely A3006/2924, A3006/2853, A3006/1746, A3006/1465, A3006/1163, A1118/1097, A2853/1746, A2853/1417, A2853/1163, A2853/1118, A2853/1097, and A2853/723 (relevant to the degree of oil unsaturation) did not offer more information than the physicochemical criteria when examined one by one. Principal component – discriminant analysis of intensity values at 2924, 2853, 1746, 1465, 1163, 1118, 1097, and 723 cm−1 led to a 100, 91, and 54.5% correct classification for the 12, 6, and 0 months stored ones, respectively. Improvement in correct classification of the latter (73–91%) was obtained when the second derivatives of various spectral ranges were treated by the same statistical approach. Frequencies assigned to stretching and/or bending of CO and CH2 groups (1020–1260 cm−1) produced the best discrimination among samples. Findings are discussed with reference to literature reports about FT-MIR applicability under various oxidation conditions of virgin olive oil (VOO). A systematic inter-laboratory study is suggested in order FT-MIR/ATR to be used as a robust tool in VOO quality control. Practical applications: There is an increasing awareness among consumers and olive oil producers and distributors about virgin olive oil freshness and discussions are on the way for updating of the relevant EU regulations on its quality characteristics. Modernization of methods of analysis and introduction of additional criteria can be achieved by the employment of powerful techniques that can provide solid, multiple type of information with little sample manipulation. FT-MIR/ATR requires no sample preparation, the spectra are related to all chemical components of the lipid matrix and are recorded over a broad region (4000–400 cm−1) in few minutes. Chemometric analysis of the numerous peaks extracts all of the valuable information that can enhance claims or disputes about the oxidative status of a virgin olive oil (e.g., freshness or loss of freshness). Moreover, FT-MIR apparatus has multiple uses in the oil industry (authenticity, origin) so that an investment on such a green technique is advisable.

The present study focuses on the examination of the radical scavenging activity trend of some natural hydroxybenzaldehydes and their corresponding acids with the aid of DFT/B3LYP. Values of computed molecular descriptors (bond dissociation enthalpy, BDE; ionization potential, IP; proton affinity, PA; electron transfer energy, ETE) characterizing the hydrogen atom or electron donating efficiency of parent compounds and ions were discussed considering published experimental findings for the radical scavenging activity of the same compounds using various methods (Rancimat, crocin bleaching, trolox equivalent antioxidant capacity and 2,2-diphenyl-1-picrylhydrazyl assays). Calculations in the gas and/or liquid phase (benzene, methanol, water) were performed to approximate the activity in a lipid substrate or in solution. BDE values could predict the activity of the compounds when hydrogen atom transfer prevailed. Thus, protocatechuic ( 1 ) aldehyde, syringaldehyde ( 2 ) and their respective acids ( 1′ , 2′ ) were predicted to be the most efficient hydrogen atom donors, in line with Rancimat data. In polar media, where electron donation should be favored for hydroxybenzaldehydes, experimental findings could not always be supported by molecular descriptors. Combined information from various descriptors, as shown for DPPH data, could justify the higher efficiency of 1 over that of 1′ and 2′ . The results document further the use of computed molecular descriptors as a green tool that can facilitate antioxidant activity studies and selection of efficient antioxidants.

Ligustrum japonicum and Olea europaea leaf extracts prepared via domestic techniques were studied for antioxidant and aldose reductase inhibitory activity (ARI) in relation to individual phenol/flavonoid composition (HPLC-various detection means) and content. On the same extract weight basis L. japonicum leaf extracts, poorer in total polar phenol (TPP) content and in most cases in flavonoids, were less efficient than olive leaf extracts in radical scavenging and in retarding lipid oxidation. On the same TPP content basis, the former were of comparable efficiency in radical scavenging but exhibited lower activity than the latter in bulk oils or liposomes. L. japonicum extracts were characterized by the presence of verbascoside and apigenin derivatives, whereas O. europaea extracts by that of oleuropein. Superiority of L. japonicum infusion versus O. europaea infusion was evidenced using the ARI activity assay either on the same extract weight or on TPP content basis. The former was also superior in comparison to oleuropein, tyrosol, and hydroxytyrosol activity. These findings suggest the presence of other active compounds besides the so far identified phenolics and enhance our view on the importance of Oleaceae plants as sources of bioactive compounds beyond O. europaea. Practical applications: Oleaceae plants are a unique source for the secoiridoid oleuropein or verbascoside that confer well documented biological properties. On continuation of our effort to valorize plants of this family as sources for functional constituents we examined, in parallel, leaf extracts of the less investigated species Ligustrum japonicum versus those of Olea europaea L. The data presented for the extracts obtained via domestic preparations techniques (infusions, decoctions, tinctures) are expected to attract the interest of those involved in herbal teas and dietary supplements sector.

A series of 3′,4′-dihydroxy natural aurones differing in ring A substitution pattern have been studied with regards to their radical scavenging potential in the gas and in the liquid phase (benzene, water) using density functional theory (DFT) and the Becke's 3 Lee Yang Parr functional (B3LYP). Based on O–H bond dissociation enthalpy (BDE) and adiabatic ionization potential (IP) values, all tested aurones are expected to be more efficient hydrogen atom and electron donors than luteolin. The substitution pattern in ring A may have an impact on hydrogen atom donating activity of the compounds as phenolic and non-phenolic hydrogen atoms may be donated. Substitution affected polarity and in certain cases planarity of compounds, which may influence efficiency in real systems. Hydration at C-2 (auronols) affected polarity, electron donation and stability of the derived phenoxy radical at C-4′ and loss of planarity, rendering membrane penetration difficult. Change in C ring configuration (isoaurones) resulted in lower IP and O–H BDE value at C-6. The current findings suggest that aurones deserve more attention for food or pharmaceutical applications as antioxidants.

Alkannins and shikonins (A/S) are naturally occurring isohexenylnaphthazarins (IHNs) of great interest in the field of life sciences due to their broad spectrum of biological properties and are used as food colourants in some countries. In the present study for the first time assessment of the radical scavenging activity of A/S and selected derivatives was carried out using the Crocin Bleaching Assay (CBA) and a modified DPPH assay. Exploration of structure-radical scavenging activity relationship (SAR) was approached with a wide range of A/S derivatives. To accomplish this task, a computational approach was also employed for the two enantiomers and other structurally related compounds. The findings indicated that the side chain –OH group at C-1′ has a positive effect to the radical scavenging properties of alkannin/shikonin by assisting hydrogen atom donation from this carbon atom. Thus, alkannin and shikonin were more potent than deoxyshikonin. Esterification of that hydroxyl group was critical for the activity of the respective compounds (acetyl-, isovaleryl- and β,β-dimethylacryl-shikonin). All of the examined IHN derivatives were found experimentally less potent scavengers than naphthazarin.

A health claim on "olive oil polyphenols", namely, hydroxytyrosol and its derivatives, was recently approved by EC Regulation 432/2012. As no official method exists so far for the complete separation of all forms of hydroxytyrosol and tyrosol present in the oil, it is of utmost importance to find a simple, reproducible, and undisputable protocol to protect consumers and avoid unfair competition. In this study two hydrolysis protocols for the complex forms either in the polar fraction of the oil (protocol 1) or directly in the oil (protocol 2) were comparatively applied to a series of extra virgin olive oils. Protocol 1 gave at least 50% higher levels of total hydroxytyrosol and tyrosol. Nevertheless, the minimum amount of 5 mg/20 g oil of phenols was fulfilled only when suitable correction factors were introduced in the calculations to account for the differences in the mass between simple and complex phenols. Changes in the terminology used in the health claim are also proposed.

Olive leaf-olive oil preparations were obtained by vigorous mixing at various levels of addition (5, 10, 15%w/w) of new or mature leaves. After removal of the plant material via centrifugation, quality and sensory characteristics of the preparations were determined. Oxidative stability (120°C, 20 L/h) and DPPH radical scavenging were increased ∼2–7 fold depending on the level of leaves used due to enrichment with polar phenols, mainly oleuropein, and a-tocopherol. The extraction process affected the chlorophyll content and organoleptic traits as indicated by acceptability and preference tests (n = 50). Forty-four % of the panelists identified a strong pungency in preparations with 15% w/w new leaves. Fifty-four % of them identified a bitter taste in those with 15% w/w mature leaves, which was attributed to high levels of oleuropein (∼200 mg/kg oil). Olive leaf-olive oil preparations had interesting properties regarding antioxidants present that can attract the interest of a functional product market. Practical applications: The wider use of olive oil and derived products is highly desirable. In this sense, the current study presents data that support introduction to the market of a new specialty olive oil based solely on olive tree products (olive oil and leaves). Thus, in addition to olive oil and olive paste, a new product, that is an olive oil enriched with olive leaf antioxidants, especially oleuropein produced via a “green” technique (mechanical means instead of extraction with organic solvent) can be made available for consumers.