Association Between In Vitro Antiradical Activity and Ferric Reducing Power in Aged Red Wines: A Mechanistic Approach

Polyphenolic phytochemicals present in certain plant tissues exhibit multifunctional properties, in terms of expressing in vitroantioxidant activity. In the case of wines, which can be considered as very complex mixtures of polyphenols, a trend has been revealed by previous studies regarding the correlation of values from antioxidant tests based on different chemical backgrounds. In this respect, 25 aged red wines, along with some characteristic polyphenolic antioxidants, were employed to carry out specific antioxidant tests, including the widely used DPPH• stable radical and a ferric reducing assay. The results showed that the values arising from these two tests correlated very well (r2 0.8761) at a 99.9% significance level (p<0.001). On such a basis, and using the information derived from the examination of the pure components, the findings were discussed from a mechanistic point of view to examine whether particular red wine constituents are responsible for the antioxidant behaviour observed.

Note: A Comparative Study on the in Vitro Antiradical Activity and Hydroxyl Free Radical Scavenging Activity in Aged Red Wines

The antiradical and hydroxyl free radical scavenging activities were estimated in twenty-five, aged red wines from different areas in Greece. The antiradical activity (AAR) was determined by means of the wellknown DPPH• method, and its values ranged from 24.7 to 125.1. A novel, chemiluminescence-based, highly sensitive assay was applied for determination of the hydroxyl free radical scavenging activity (SAHFR), which varied from 1.62 to 12.22 mM quercetin equivalents. The values from the two assays correlated very well (r2 =0.8542, P<0.001), which confirmed an important relationship between SAHFR and AAR. This tendency in aged red wines, which may be significant in evaluating the antioxidant behaviour of red wine polyphenols, is discussed on the basis of previous research and relevant data.

Evaluation of anti-oxidant and acetylcholinesterase activity and identification of polyphenolics of the invasive weed Dittrichia viscosa

INTRODUCTION

The bioactive metabolites derived from weeds have attracted the interest of the food and pharmaceutical industries due to their health benefits.

OBJECTIVE

To evaluate the anti-oxidant and acetylcholinesterase activity of Dittrichia viscosa extracts and characterise the polyphenolic metabolites using the LC coupled with diode-array detection (DAD) and positive mode electrospray ionisation (ESI) MS method with a view to evaluating the exploitation potential of this invasive weed.

MATERIALS AND METHODS

Roots and aerial parts of D. viscosa were extracted with solvents of increasing polarity and their major polyphenolic metabolites were identified by LC - DAD/ESI(+)/MS. The total phenolic content of the extracts was determined using the Folin-Ciocalteu method, while their anti-oxidant activity was evaluated on the basis of their ability to scavenge the stable free radical 1,1-diphenyl-2-picrylhydrazyl (DPPH) and hydrogen peroxide. Thin-layer chromatography was used to screen for acetylcholinesterase inhibitors.

RESULTS

Stem extracts gave the highest phenolic content, whereas the roots showed the lowest content. Twenty-five polyphenolic constituents of the extracts were tentatively characterised according to their MS and UV spectroscopic data. Among the extracts studied, roots-ethyl acetate and flowers-diethyl ether revealed the highest activity according to the DPPH and chemiluminescence assays respectively.

CONCLUSION

The metabolic profile of D. viscosa was studied and the structures of the major polyphenolic metabolites were tentatively assigned based on their MS and UV-vis spectra. The extracts exhibited high levels of anti-oxidant and acetylcholinesterase inhibitory activity and the inhibitors are probably localised mainly in flowers and roots.

Evaluation of anti-oxidant activity and identification of major polyphenolics of the invasive weed Oxalis pes-caprae

INTRODUCTION

Phytochemical analyses of weeds, many of which have been used in traditional medicine worldwide, could lead to the identification of secondary metabolites with significant biological activity.

OBJECTIVE

To perform an assessment of the chemical composition and exploitation potential of the invasive weed Oxalis pes-caprae. To evaluate the anti-oxidant activity of its extracts and isolate and characterise polyphenolic metabolites using LC-DAD-MS (ESI+) and NMR methods.

METHODOLOGY

Aerial parts of the invasive weed O. pes-caprae were extracted with solvents of increasing polarity and their major polyphenolic metabolites were identified by LC-DAD-MS (ESI+). The total phenolic content of the extracts was determined using the Folin-Ciocalteu method, while their anti-oxidant activity was evaluated on the basis of their ability to scavenge the stable free radical 1,1-diphenyl-2-picrylhydrazyl and hydrogen peroxide.

RESULTS

The major polyphenolic constituents of the extracts were tentatively characterised as chlorogenic acid, quinic ferulate, luteolin glucoside and cernuoside according to their MS and UV spectroscopic data. Cernuoside, an aureusidin glucoside, was isolated from the methanolic extract of the weed's flowers and its structure was unambiguously identified by 1D- and 2D-NMR spectroscopy. The butanol extract of O. pes-caprae displayed the highest anti-oxidant activity.

CONCLUSION

The metabolic profile of O. pes-caprae was studied and the structures of the major polyphenolic metabolites based on their MS and UV-vis spectra were tentatively assigned. The aureusidin glucoside cernuoside was isolated and characterised for the first time from O. pes-caprae. The extracts exhibited high levels of anti-oxidant activity.

Improving yeast strains using recyclable integration cassettes, for the production of plant terpenoids

BACKGROUND

Terpenoids constitute a large family of natural products, attracting commercial interest for a variety of uses as flavours, fragrances, drugs and alternative fuels. Saccharomyces cerevisiae offers a versatile cell factory, as the precursors of terpenoid biosynthesis are naturally synthesized by the sterol biosynthetic pathway.

RESULTS

S. cerevisiae wild type yeast cells, selected for their capacity to produce high sterol levels were targeted for improvement aiming to increase production. Recyclable integration cassettes were developed which enable the unlimited sequential integration of desirable genetic elements (promoters, genes, termination sequence) at any desired locus in the yeast genome. The approach was applied on the yeast sterol biosynthetic pathway genes HMG2, ERG20 and IDI1 resulting in several-fold increase in plant monoterpene and sesquiterpene production. The improved strains were robust and could sustain high terpenoid production levels for an extended period. Simultaneous plasmid-driven co-expression of IDI1 and the HMG2 (K6R) variant, in the improved strain background, maximized monoterpene production levels. Expression of two terpene synthase enzymes from the sage species Salvia fruticosa and S. pomifera (SfCinS1, SpP330) in the modified yeast cells identified a range of terpenoids which are also present in the plant essential oils. Co-expression of the putative interacting protein HSP90 with cineole synthase 1 (SfCinS1) also improved production levels, pointing to an additional means to improve production.

CONCLUSIONS

Using the developed molecular tools, new yeast strains were generated with increased capacity to produce plant terpenoids. The approach taken and the durability of the strains allow successive rounds of improvement to maximize yields.

Polyphenolic composition and antioxidant characteristics of kumquat (Fortunella margarita) peel fractions

The polyphenolic composition of two Fortunella margarita (Nagami kumquat) specimens from Greece and Egypt was investigated employing fractionation by solvent partition and liquid chromatography-mass spectrometry. The main groups of phenolics identified in the different fractions generated were C-glycosylated flavones, O-glycosylated flavones, C-glycosylated flavanones, O-glycosylated flavanones, flavonols, chalcones, phenolic acids and derivatives thereof. The antioxidant potency of the fractions was assessed using two representative in vitro tests, including antiradical activity and hydroxyl free radical scavenging activity. It was revealed that the ethyl acetate fractions from both specimens contained the higher polyphenol content and exhibited the better antioxidant characteristics. The results indicated that F. margarita peels may be regarded as a rich source of potentially bioactive polyphenols.

Natural and synthetic 2'-hydroxy-chalcones and aurones: synthesis, characterization and evaluation of the antioxidant and soybean lipoxygenase inhibitory activity

A series of 2'-hydroxy-chalcones and their oxidative cyclization products, aurones, have been synthesized and tested for their antioxidant and lipoxygenase inhibitory activity. The natural product aureusidin (31) was synthesized in high yield by a new approach. An extensive structure-relationship study was performed and revealed that several chalcones and aurones possess an appealing pharmacological profile combining high antioxidant and lipid peroxidation activity with potent soybean LOX inhibition.

Antioxidant small molecules confer variable protection against oxidative damage in yeast mutants

To assess the capacity of small molecules to function as antioxidants in pathologic conditions, a set of yeast assays utilizing strains deficient in the antioxidant machinery was applied with measurements of reactive oxygen species (ROS), glutathione (GSH/GSSG), and induction of the stress responsive proteins oye2 and oye3. Yeast strains deficient in superoxide dismutase (Delta sod1), catalase A (Delta cta1), and double-deficient in Old Yellow enzyme 2 and glutathione reductase 1 (Delta oye2 glr1) were supplemented with ascorbic acid, beta-carotene, caffeic acid, or quercetin, subjected to pro-oxidant insult, and monitored for growth recovery. Ascorbic acid and caffeic acid protected cells under most circumstances, whereas beta-carotene and quercetin protection was highly context dependent, exhibiting protection in some cases and inhibition in others. Beta-carotene and quercetin elevated substantially endogenous levels of ROS in some yeast mutants. Quercetin supplementation increased significantly GSH and GSSG levels but could not maintain GSH levels in H(2)O(2)-exposed cells. Induction of the stress response machinery was manifested by the strong up-regulation of a chromosomally encoded OYE2-GFP fusion. In the case of quercetin, there was simultaneous induction of OYE3-GFP, which was previously shown to sensitize cells to H(2)O(2)-induced programmed cell death (PCD). Taken together, the results show that mutations in the antioxidant machinery affect significantly the capacity of dietary antioxidants to protect cells.

Recovery of Bioactive Flavonols from Onion Solid Wastes Employing Water/Ethanol-Based Solvent Systems

Food processing by-products and wastes represent in many instances major polluting agents, since they bear a significant load of organic bio-molecules and particularly high chemical and biological oxygen demand (COD and BOD) levels. In this regard the development of processes that will aim at reducing the polluting load by removing added-value phytochemicals from agriculture-food wastes becomes imminent. In the present study, a first approach regarding the efficient recovery of bioactive flavonols from onion solid wastes has been attempted. Major flavonols were identified by liquid chromatography-mass spectrometry techniques and recovery was achieved by using environmentally friendly and food-compatible solvent systems, composed of water/ethanol, and acidified with either acetic or citric acid and HCl. Initial screening of various mixtures showed that significantly higher recoveries (P<0.001) can be attained by using 60% ethanol containing 0.1% HCl. The assessment of factors affecting yield, including extraction time and temperature, was accomplished using a series of extractions on the basis of a 3 × 3 factorial design model. The results obtained showed that maximization of yield is dependent upon increasing both extraction time and temperature.

Beta-orcinol metabolites from the lichen Hypotrachyna revoluta

Four new beta-orcinol metabolites, hypotrachynic acid (1), deoxystictic acid (2), cryptostictinolide (3) and 8'-methylconstictic acid (4) along with the metabolites 8'-methylstictic acid (5), 8'-methylmenegazziaic acid (6), stictic acid (7), 8'-ethylstictic acid (8) and atranorin (9), that have been previously described, were isolated for the first time from the tissue extracts of the lichen Hypotrachyna revoluta (Flörke) Hale. The structures of the new metabolites were elucidated on the basis of extensive spectroscopic analyses. Radical scavenging activity (RSA) of the metabolites isolated in adequate amounts, was evaluated using luminol chemiluminescence and comparison with Trolox.

Modelling the dynamic structure of biological state-based systems

The paper discusses the modelling aspects of systems with dynamic processes and dynamic structure. A combination of models bringing together the benefits of two paradigms, Population P Systems and Communicating X-machines, is introduced. A simple case study is used in order to illustrate the potential of the combined use of the two methods.

Storage of olives (Olea europaea L.) under CO2 atmosphere: liquid chromatography-mass spectrometry characterization of indices related to changes in polyphenolic metabolism

Olives (Olea europaea cv. Chondrolia) were stored under a CO2 atmosphere immediately after harvesting for a period of 12 days. Samples obtained at 24-h intervals were analyzed by HPLC to identify components that may reflect changes in the biochemical behavior of the tissue. Four substances were shown to undergo significant fluctuations during storage, while their evolution was found to be different in olives stored under CO2 from those stored under regular atmospheric conditions (control). On the basis of data provided by liquid chromatography-electrospray ionization mass spectrometry, these substances were tentatively identified as hydroxytyrosol glucoside, demethylated ligstroside aglycone, ibotalactone A methyl ester, and verbascoside. The data are discussed in relation to the effect of postharvest treatments of olives for purposes of manipulating their polyphenolic content and plausible development of novel debittering processes.

Antioxidant potential of six pine species

The aim of the study was to evaluate the antioxidant efficacy of extracts obtained from six Pinus species (P. pinea, P. brutia, P. radiata, P. halepensis, P. attenuata, P. nigra) growing in natural forests in Southern Greece. Specimens of fresh, dry needles and pine bark were extracted and fractionated with a variety of organic solvents and the efficient concentration and their radical scavenging activity was evaluated by the Co(II)/EDTA induced luminol plateau chemiluminescence assay.

Novel quality control methods in conjunction with chemometrics (multivariate analysis) for detecting honey authenticity

The importance of honey has been recently upgraded because of its nutrient and therapeutic effect. The adulteration of honey increased exponentially in terms of both geographic and/or botanical origin. Therefore, the need has arisen for more effective quality control methods aiming at detecting adulteration. Various novel, fast, and accurate methods like AAS, HPLC, GC-MS, ES-MS, TLC, HPAED-PAD, NMR, FT-Raman, and NIR have enriched the arsenal of analytical chemist in this direction. However, apart from these novel methods, the application of multivariate analysis and, in particular, PCA, CLA, and CA, proved to be extremely useful for grouping and detecting honey of various origins. Mineral and trace element analysis were repeatedly shown to be a very effective means for the classification purposes of honey of various origins (geographical and botanical).

Determination of hydrogen peroxide scavenging activity of cinnamic and benzoic acids employing a highly sensitive peroxyoxalate chemiluminescence-based assay: Structure–activity relationships

A series of cinnamic acids along with their corresponding benzoate analogues were tested for their ability to scavenge hydrogen peroxide (H(2)O(2)), by using a highly sensitive, peroxyoxalate chemiluminescence assay. Among benzoic acid derivatives, vanillic acid (3-hydroxy-4-methoxybenzoic acid) was found to be the most efficient H(2)O(2) scavenger with its hydrogen peroxide scavenging activity (SA(HP)) being 170.20 microM(-1), whereas protocatechuic acid (3,4-dihydroxybenzoic acid) exhibited the weakest activity (5.90 microM(-1)). Caffeic acid (3,4-dihydroxycinnamic acid) was the strongest antioxidant amongst cinnamate derivatives with a SA(HP) = 8.2 microM(-1), as opposed to m-coumaric acid (2-hydroxycinnamic acid), which was found to be a poor hydrogen peroxide scavenger (SA(HP) = 0.18 microM(-1)). Comparison between the two groups revealed that benzoate derivatives are much stronger hydrogen peroxide quenchers in relation with their cinnamate analogues, and this finding was discussed on a basis of structure-activity relationships and comparative assessment of other antioxidant characteristics.

A new alkaloid from Narcissus serotinus L

A new alkaloid derivative of [2]benzopyrano-[3,4-c] indole, isomer of 3-epimacronine, 4-methoxy-5-methyl-1,2,3,5,6,6alphaR-hexahydro-[1,3]dioxolo[4',5':6,7]isochromeno [3,4-c]indol-8-one, has been isolated from Narcissus serotinus L. (Amaryllidaceae) and its structure was elucidated by mass and spectral analysis.

Sonochemical reduction of the antioxidant activity of olive mill wastewater

The use of ultrasonic irradiation to reduce the antioxidant activity of olive oil mill wastewaters (OMWs) originating from two-phase and three-phase decanters was examined. Sonication of diluted OMW samples was conducted at ultrasonic frequencies of 24 and 80 kHz, an applied power varying between 75 and 150 W, and liquid bulk temperatures varying between 25 and 60 degrees C. At the conditions in question, the reduction in antioxidant activity was found to increase with decreasing temperature and increasing power and frequency. Addition of NaCl in the samples also appeared to enhance reduction. Antioxidant activity of OMW samples was assessed using the recently developed Co(II)/ethylenediaminetetraacetic acid (EDTA)-induced luminol chemiluminescence analytical protocol, while the total phenolic load was measured according to the Folin-Ciocalteu method.

Measuring the antioxidant activity of olive oil mill wastewater using chemiluminescence

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 two-phase system. The relationship between antioxidant values and total phenolic content is also discussed.

Analysis of antioxidant compounds in sweet orange peel by HPLC-diode array detection-electrospray ionization mass spectrometry

HPLC-diode array detection-electrospray ionization mass spectrometry was used to determine qualitatively and quantitatively the flavonoid content of several fractions and residues of extracts of Greek navel sweet orange peel (Citrus sinensis) from the region of southern Greece (Leonidi-Tripoli). The main groups of flavonoids found according to HPLC retention times, spectral data and literature references were polymethoxylated flavones, C-glycosylated flavones, O-glycosylated flavones, O-glycosylated flavanones, flavonols and phenolic acids and their derivatives. The ethyl acetate fraction which has been shown in previous work to possess the best radical scavenging activity among the others was found to contain C-glycosylated flavones, polymethoxylated flavones, O-glycosylated flavones, O-glycosylated flavanones, two phenolic acid derivatives and two unknown compounds, all in low concentrations. The group of C-glycosylated flavones was reported for the first time in the peel of Navel sweet orange. The C-glycosylated flavones found according to their spectral characteristics and literature were 6-C-beta-glucosyldiosmin, 6,8-di-C-glucopyranosylapigenin, 6,8-di-C-beta-glucosyldiosmin and two unknown. The results suggest that the ethyl acetate fraction of navel Citrus sinensis peel consists of significant antioxidant compounds and can be used as a food additive of natural origin or a pharmaceutical supplement using as a source of peel the byproducts of the orange juice industry.

An analytical survey of the polyphenols of seeds of varieties of grape (Vitis vinifera) cultivated in Greece: implications for exploitation as a source of value-added phytochemicals

Seed samples from 12 white and 25 red international and Hellenic native grape varieties (Vitis vinifera) were screened for their polyphenolic composition. The polyphenols determined were mainly of low molecular weight, including gallic acid, catechin, epicatechin, epicatechin gallate, epigallocatechin, epigallocatechin gallate and the procyanidins B1 and B2. Average values of total content for white and red varieties (376 and 388 mg/100 g seeds, respectively) were very similar. Comparable results were observed with respect to the individual polyphenol content with seeds from red varieties being, in general, slightly richer. The predominant flavanol monomer in white and red varieties was catechin (which accounted for 50.5 and 49.3%, respectively, of the total content), whilst gallic acid and epigallocatechin were the constituents showing the lowest content, respectively. The data obtained are discussed with regard to the exploitation of grape seeds as a low-cost source of value-added phytochemicals.