Home About us Contact
|
Home About us Contact | ||
|
|
||
Phenolic Compounds (phenolic + compound)
Kinds of Phenolic Compounds Selected AbstractsPHENOLIC COMPOUNDS, TOCOPHEROLS AND OTHER MINOR COMPONENTS IN VIRGIN OLIVE OILS OF SOME TUNISIAN VARIETIESJOURNAL OF FOOD BIOCHEMISTRY, Issue 2 2007D. KRICHENE ABSTRACT The phenols, ,-tocopherols, fatty acids and oxidative stability of six monovarietal virgin olive oils (VOOs) were determined. Fourteen phenolic compounds were detected and quantified by solid phase extraction and reversed phase-high performance liquid chromatography. Dialdehydic form of elenolic acid linked to tyrosol and hydroxytyrosol, oleuropein and ligstroside aglycones were the main components in all samples. Pinoresinol was the most abundant component in lignan fraction. The total phenol content of these monovarietal oils varied from 66.82 mg/kg in "Neb Jmel" oil to 662.74 mg/kg in "El Hor" oil. A wide range of ,-tocopherol contents was also noticed; it varied from 141.94 mg/kg in "Semni" variety to 364.23 mg/kg in "Jdallou" variety. With regard to pigments, chlorophylls and carotenoids were found at variable concentrations: with median values of 11.33 and 3.10 mg/kg, respectively. Among the studied varieties, "Oueslati" and El Hor were characterized by the lowest levels of palmitic and linoleic acids and the highest values of oleic acid. [source] PHENOLIC COMPOUNDS IN THE FLESH OF KOREAN APPLE CULTIVAR, BUSAJOURNAL OF FOOD BIOCHEMISTRY, Issue 6 2002HEA-JEUNG WHANG ABSTRACT Phenolic compounds were purified from Busa, the most widely cultivated apple cultivar in Korea, by a sequential separation employing PVPP, Ambertite XAD-2 and Sephadex LH-20 column chromatography. Phenolic compounds in some fractions were farther identified by directly comparing with corresponding phenolic standards after separation on HPLC and GC-MS. The phenolic compounds identified were p-hydoxybenzoic, protocatechuic, 4-hydroxymetyl-benzonic, caffeic, p-coumaric, o-coumaric, ferulic, sinapic and chlorogenic acids and (±)-catechin. Among them, 4-hydroxymethylbenzoic, protocatechuic, o-coumaric and sinapic acids were ascertained as new members of a family of phenolic acids present-in apples. Also the presence of rutin, quercetin and phlorizin in apples were demonstrated using HPLC. [source] SUPERCRITICAL CARBON DIOXIDE SELECTIVITY TO FRACTIONATE PHENOLIC COMPOUNDS FROM THE DRY ETHANOLIC EXTRACT OF PROPOLISJOURNAL OF FOOD PROCESS ENGINEERING, Issue 1 2010LOSIANE C. PAVIANI ABSTRACT The global yield and composition of extracts obtained by supercritical carbon dioxide (SC-CO2) extraction from a dry ethanolic extract of propolis were measured in order to determine the possibility of using SC-CO2 to fractionate components of interest present in these extracts. The global yield extraction was measured, and also the concentrations of the following phenolic compounds in the resulting supercritical fluid extracts (SFEs): 3,5-diprenyl-4-hydroxycinnamic acid (known as artepillin C), 3-prenyl-4-hydroxycinnamic acid, 4-hydroxycinnamic acid (p- coumaric acid) and 4-methoxy-3,5,7-trihydroxyflavone (kaempferide), of which artepillin C was the target component of greatest interest. The results showed extraction yields between 3.82 (at 150 bar) and 13.07% (at 350 bar), which could be highly correlated with the density of the SC-CO2 at a constant temperature of 60C. The resulting concentrations in the SFE indicated that the selectivity of the carbon dioxide could be manipulated, and it was more selective at lower pressures, although with lower extraction yields. PRACTICAL APPLICATIONS Supercritical fluid extraction is an interesting process for the production of natural extracts because it is a clean process, and extractions using carbon dioxide (CO2) as the solvent have been gaining attention in recent years. This study presented important aspects with respect to the fractionation of a dry ethanolic extract of propolis using supercritical carbon dioxide, and it is important to explore the potential applications of propolis extracts and the biological properties of its fractions in the food, pharmaceutical and cosmetic industries, such as in dental hygiene products, wound healing creams and antibacterial soaps. [source] Study of the Responses of a Sonogel-Carbon Electrode Towards Phenolic CompoundsELECTROANALYSIS, Issue 9 2005Cordero-Rando, Ma del Abstract The electrochemical behavior of a sonogel-carbon electrode towards nine phenolic compounds (chloro-, nitro- and alkyl-phenols) was studied; one of them (4-chloro-3-methylphenol) was used to evaluate characteristics of the electrode, such as accumulation and cleaning procedure of the electrode surface, reproducibility of the measurements, and influence of time from fabrication on electrochemical response. A polyethyleneglycol-modified sonogel-carbon electrode was found to improve the electrochemical response towards the analyte. A linear relationship between peak height and concentration in the range 0.005,0.5,mg L,1 was obtained, with a detection limit of 2.8,,g L,1. The studies of electrochemical parameters, as well as interferences, are also included. [source] Composite Multienzyme Amperometric Biosensors for an Improved Detection of Phenolic CompoundsELECTROANALYSIS, Issue 22 2003B. Serra Abstract A biosensor design, in which glucose oxidase and peroxidase are coimmobilized by simple physical inclusion into the bulk of graphite-Teflon pellets, is reported for the detection of phenolic compounds. This design allows the "in situ" generation of the H2O2 needed for the enzyme reaction with the phenolic compounds, which avoids several problems detected in the performance of single peroxidase biosensors as a consequence of the presence of a high H2O2 concentration. So, a much lower surface fouling was found at the GOD-HRP biosensor in comparison with a graphite-Teflon-HRP electrode, suggesting that the controlled generation of H2O2 makes more difficult the formation of polymers from the enzyme reaction products. The construction of trienzyme biosensors, in which GOD, HRP and tyrosinase were coimmobilized into the graphite-Teflon matrix is also reported, and their performance was compared with that of GOD-HRP bienzyme electrodes. The practical applicability of the composite multienzyme amperometric biosensors was evaluated by the estimation of the phenolic compounds content in waste waters from a refinery, and the results were compared with those obtained by using a colorimetric official method based on the reaction with 4-aminoantipyrine. [source] Radical Scavenging Activity and Phenolic Compounds in Persimmon (Diospyros kaki L. cv. Mopan)JOURNAL OF FOOD SCIENCE, Issue 1 2008X.N. Chen ABSTRACT:, The Mopan persimmon (Diospyros kaki L. cv. Mopan) is the major cultivar of astringent persimmon in northern China. This study investigates the radical scavenging activity against ABTS and DPPH radical, and the content of total and individual phenolics (catechin, epicatechin, epigallocatechin, chlorogenic acid, caffeic acid, and gallic acid) with apple, grape, and tomato as controls. The radical scavenging activities against ABTS and DPPH radicals of the Mopan persimmon are 23.575 and 22.597 ,m trolox eq/g f.w., respectively. These findings suggest that the Mopan persimmon's antioxidant activity is significantly (P < 0.05) stronger than that of reference materials. The Mopan persimmon showed the highest content of total phenolics among the 4 materials tested. Significant correlations (R2= 0.993, P < 0.05, ABTS radical; R2= 0.980, P < 0.05, DPPH radical) are found between the total phenolics and the radical scavenging activities. The total content of these 6 kinds of phenolics (catechin, epicatechin, epigallocatechin, chlorogenic acid, caffeic acid, and gallic acid) is significantly correlated (R2= 0.831, P < 0.05, ABTS radical; R2= 0.745, P < 0.05, DPPH radical) with the individual radical scavenging activity of the 4 materials, although the total content of the 6 phenolics accounts for no more than 20% of the total phenolics in the Mopan persimmon. Gallic acid exhibits the strongest antioxidant activity in all 6 kinds of phenolics and its content is the largest in the Mopan persimmon, presumably being responsible for its much higher antioxidant activity as compared to apple, grape, and tomato. [source] Isolation and Characterization of Virgin Olive Oil Phenolic Compounds by HPLC/UV and GC-MSJOURNAL OF FOOD SCIENCE, Issue 4 2001M. Tasioula-margari ABSTRACT This research examined the phenolic fraction of extra virgin olive oil samples from Lianolia variety olives grown in the region of Preveza, Greece. Phenolic compounds were extracted from oil samples, separated by reversed-phase high-performance liquid chromatography (HPLC), and characterized by gas chromatography-mass spectrometry (GC-MS). Both simple and complex phenols were detected with the latter being the most abundant. 3,4-Dihydroxyphenyl ethanol (hydroxytyrosol) and p-hydroxyphenylethanol (tyrosol) predominated among the simple phenols. Complex phenolic compounds were further separated by preparative HPLC and analyzed by GC-MS before and after hydrolysis. The presence of hydroxytyrosol and tyrosol derivatives was confirmed. Both derivatives were always present in greater quantities and made up an average exceeding 70% in all samples analyzed. [source] Induction of Phenolic Compounds in Pea (Pisum sativum L.) Inoculated by Rhizobium leguminosarum and Infected with Orobanche crenataJOURNAL OF PHYTOPATHOLOGY, Issue 11-12 2007Y. Mabrouk Abstract Parasitic plants are among the most important problematic weeds, they are responsible of major losses of many crops. Early growth stages, such as seed germination stimulated by host root exudates and tubercle development, are key phases for these parasites development. Inhibition of these early phases could be a general strategic option for parasitic plants management. In our previous study, we have demonstrated that some Rhizobium leguminosarum strains decrease pea infection by Orobanche crenata and germinated seeds enhanced browning symptoms. These observations suggested the probability of toxic compounds accumulation such as gallic acid and naringenin used as a defence strategy by inoculated pea plants. In this study, we demonstrate that these two phenolic compounds cause severe physiological disorder of germination broomrape seeds. They inhibited germination of O. crenata seeds induced by strigol analogue GR24, and caused a browning reaction in germinated seeds. [source] Biocontrol and Plant Pathogenic Fusarium oxysporum -Induced Changes in Phenolic Compounds in Tomato Leaves and RootsJOURNAL OF PHYTOPATHOLOGY, Issue 7-8 2007Y. Panina Abstract The biocontrol fungus Fusarium oxysporum strain CS-20 was previously shown to reduce the incidence of Fusarium wilt of tomato through an uncharacterized host-mediated response. As phenolic compounds are involved in the defence response of tomato to pathogens and other stressors, this work was undertaken to determine whether biocontrol strains induced changes in phenolic compounds in leaves and roots of tomato seedlings in the presence and absence of pathogenic F. oxysporum f. sp. lycopersici. Roots of intact tomato seedlings were placed in water or aqueous fungal spore suspensions. Two biocontrol F. oxysporum strains [CS-20 (host-mediated mechanism) and 85SK-1 (control mechanism unknown)] and two plant pathogenic strains of F. oxysporum f. sp. lycopersici Race 1 were used. After 24 or 72 h exposure, phenolic compounds were extracted from leaves and roots before identification by HPLC. There were significant qualitative and quantitative differences between the two sampling times. Compared with the control treatment, strain CS-20 significantly altered (usually increasing) the ferulic, caffeic and vanillic acid contents, and concentrations once unidentified phenolic compounds recovered from leaves and roots. In another experiment, tomato seedlings growing in sterile sand were drenched with spores of strain CS-20 the day before treating them with varying concentrations of spores of the pathogen for 24 or 72 h. The amount of pathogen present did not significantly affect the plant phenolic response to the presence of strain CS-20. This work demonstrates that tomato responds within 24 h to the presence of the biocontrol strain CS-20 by alterations in secondary metabolism that are typical of resistance responses in tomato. [source] Studies on Symptom Development, Phenolic Compounds and Morphological Defence Responses in Wheat Cultivars Differing in Resistance to Fusarium Head BlightJOURNAL OF PHYTOPATHOLOGY, Issue 4-5 2002E. SIRANIDOU Abstracts Development of Fusarium head blight, caused by Fusarium culmorum, was evaluated in seven winter wheat cultivars and one spring wheat cultivar in an outdoor pot experiment. Of the cultivars studied, only the spring wheat cultivar Frontana exhibited resistance against initial infection by the fungus. Significantly higher amounts of free phenolic compounds were found in the glumes, lemmas and paleas of Frontana prior to and at all sampling times after inoculation, in comparison to the winter wheat cultivar Agent. Furthermore, the amount of p -coumaric acid increased significantly in the glumes, lemmas and paleas of the cultivar Frontana 2 days after inoculation compared to that in uninoculated spike tissues. However, the amounts of ferulic acid between inoculated and healthy plant tissues did not differ. Ultrastructural studies indicated more pronounced structural defence responses, such as cell wall appositions, in the infected lemma tissue of the resistant cultivar Frontana compared with the susceptible Agent 3 days after inoculation. Immunogold labelling of lignin revealed no differences in the density of gold particles on the cell walls of healthy lemma tissue in the two cultivars. However, density of particles increased in the infected lemma tissue of the resistant cultivar Frontana on cell walls adjacent to the fungal cells, 3 days after inoculation. The susceptible cultivar Agent showed little or no response to the infection. Phenolic compounds appear to play a role in the resistance of the cultivar Frontana to F. culmorum. [source] Changes in Cell Wall-bound Phenolic Compounds and Lignin in Roots of Date Palm Cultivars Differing in Susceptibility to Fusarium oxysporum f. sp. albedinisJOURNAL OF PHYTOPATHOLOGY, Issue 7-8 2000C. El Modafar The roots of date palm contain four cell wall-bound phenolic acids identified as p -hydroxybenzoic, p -coumaric, ferulic and sinapic acids. The ferulic acid represents the major phenolic compound since it constitutes 48.2,55.8% of cell wall-bound phenolic acids. All these phenolic acids were present in the resistant cultivar (BSTN) and the susceptible cultivar (JHL). However, the pre-infection contents of p -coumaric, ferulic and sinapic acids were greater in the resistant cultivar than in the susceptible one. For the contents of p -hydroxybenzoic acid, there was no significant difference between the resistant cultivar and the susceptible cultivar. Similarly, the pre-infection contents of lignin were approximately equal for both cultivars. Inoculation of the date palm roots by Fusarium oxysporum f. sp. albedinis induced important modifications to the contents of the cell wall-bound phenolic compounds and lignin, which made it possible to distinguish between resistant and susceptible cultivars. The post-infection contents of cell wall-bound phenolic compounds underwent a rapid and intense increase with a maximum accumulation on the tenth day for p -hydroxybenzoic acid (1.54 ,mol/g), p -coumaric acid (2.77 ,mol/g) and ferulic acid (2.64 ,mol/g) and on the fifteenth day for sinapic acid (1.85 ,mol/g). The maximum contents accumulated in the resistant cultivar were greater than those in the susceptible cultivar, namely, 11 times for p -hydroxybenzoic acid, 2.6 times for p -coumaric acid, 1.8 times for ferulic acid and 12.3 times for sinapic acid. In the susceptible cultivar, p -coumaric acid and ferulic acid contents also increased after inoculation although they did not reach the pre-infection contents of the resistant cultivar. The contents of p -hydroxybenzoic acid in the susceptible cultivar roots did not present post-infection modification and those of sinapic acid decreased instead. The lignin contents increased in both cultivars with a maximum accumulation on the fifteenth day. However, the maximum contents accumulated in the resistant cultivar roots were 1.5 times greater than those of the susceptible cultivar. These results showed clear differences between the resistant BSTN and the susceptible JHL cultivars. The implication of cell wall-bound phenolic compounds and lignin in the resistance of date palm to F. oxysporum f. sp. albedinis appears to be dependent on the speed and intensity of their accumulation with greater contents in the first stage of infection. Zusammenfassung Die Wurzeln der Dattelpalme enthalten vier zellwandgebundene Phenolsäuren, die als p -Hydroxybenzoesäure, p- Cumarsäure, Ferulasäure und Sinapinsäure identifiziert wurden. Ferulasäure ist die wichtigste phenolische Verbindung, denn sie stellt 48,2 bi 55,8% der zellwandgebundenen Phenolsäuren. Alle vier Phenolsäuren waren in der resistenten Sorte BSTN und in der anfälligen Sorte JHL vorhanden. Die Gehalte an p -Cumarsäure, Ferulasäure und Sinapinsäure waren vor der Infektion bei der resistenten Sorte jedoch höher als bei der anfälligen Sorte. Hinsichtlich des Gehalts an p -Hydroxybenzoesäure unterschieden sich die resistente und die anfällige Sorte nicht signifikant voneinander. Auch die Ligningehalte vor der Infektion waren bei beiden Sorten ungefähr gleich. Die Inokulation von Dattelpalmenwurzeln mit Fusarium oxysporum f. sp. albedinis induziert wichtige Änderungen der Gehalte an zellwandgebundenen phenolischen Verbindungen und Lignin, was eine Unterscheidung resistenter von anfälligen Sorten ermöglicht. Nach der Infektion nehmen die Gehalte an zellwandgebundenen phenolischen Verbindungen rasch und erheblich zu, mit maximaler Akkumulation am 10. Tag bei p -Hydroxybenzoesäure (1,54 ,mol/g), p -Cumarsäure (2,77 ,mol/g) und Ferulasäure (2,64 ,mol/g) sowie am 15. Tag bei Sinapinsäure (1,85 ,mol/g). Die in der resistenten Sorte akkumulierten maximalen Gehalte waren höher als die maximalen Gehalte der anfälligen Sorte , um das Elffache bei p -Hydroxybenzoesäure, das 2,6-fache bei p -Cumarsäure, das 1,8-fache bei Ferulasäure und das 2,3-fache bei Sinapinsäure. Bei der anfälligen Sorte steigen die Gehalte an p -Cumarsäure und Ferulasäure nach der Inokulation ebenfalls an, bleiben aber niedriger als die Werte der resistenten Sorte vor der Infektion. Der p -Hydroxybenzoesäuregehalt in den Wurzeln der anfälligen Sorte ist nach der Infektion nicht verändert, und der Sinapinsäuregehalt nimmt ab. Der Ligningehalt steigt bei beiden Sorten, mit maximaler Akkumulation am 15. Tag. Der maximale Gehalt in den Wurzeln der resistenten Sorte war jedoch 1,5-mal höher als bei der anfälligen Sorte. Diese Ergebnisse zeigen deutliche Unterschiede zwischen der resistenten Sorte (BSTN) und der anfälligen Sorte (JHL). Die Bedeutung der zellwandgebundenen phenolischen Verbindungen und des Lignins für die Resistenz der Dattelpalme gegen F. oxysporum f. sp. albedinis scheint von der Geschwindigkeit und der Intensität der Akkumulation abzuhängen, wobei die Gehalte im ersten Stadium der Infektion höher sind. [source] Theoretical Prediction of the Phenoxyl Radical Formation Capacity and Cyclooxygenase Inhibition Relationships by Phenolic CompoundsMOLECULAR INFORMATICS, Issue 6 2002Juan Ruiz Abstract Due to the importance of the O-H bond dissociation in the antioxidant mechanism of anti-inflammatory phenols, we studied the biradical process Ph-OH,PhO.+H. for 25 phenolic compounds using ab initio calculations. Enthalpies of reaction (,Hr), changes in the electron density at the O-H bond critical point (,OH) and total atomic charges of ortho and para carbon atoms strongly correlate with the in vitro inhibition of cyclooxygenase activity by phenols. The most active compounds have large values of the electron density at the O-H bond (,OH), thus favouring the O-H bond dissociation. In contrast, inactive compounds have small values of the electron density at the O-H bond (,OH), thus reducing the hydrogen donation ability. These results are also supported by the representation of the molecular electrostatic potentials maps. The prediction of the cyclooxygenase inhibitory activity of the proposed QSAR equations is analysed using the multilineal (MLR) method. Finally, the differences in biological activity are examined by analysing the binding interactions of active compounds in the pocket site of human COX-2 enzyme structure derived from crystallographic X -ray data. [source] Dibromomethane as One-Carbon Source in Organic Synthesis: The Mannich Base Formation from the Reaction of Phenolic Compounds with a Preheated Mixture of Dibromomethane and Diethylamine.CHEMINFORM, Issue 44 2004Yung-Son Hon Abstract For Abstract see ChemInform Abstract in Full Text. [source] Cytotoxic Prenylated Phenolic Compounds from the Twig Bark of Garcinia xanthochymusCHEMISTRY & BIODIVERSITY, Issue 5 2007Quan-Bin Han Abstract Three new hydroxylated xanthones with prenyl or geranyl substituents, compounds 1,3, were isolated from the twig bark of Garcinia xanthochymus, along with the four known compounds 1,4,5,6-tetrahydroxy-7,8-diprenylxanthone (4), 1,3,5,6-tetrahydroxy-4,7,8-triprenylxanthone (5), garciniaxanthone E (6), and 6-prenylapigenin (7). Their structures were elucidated by extensive spectroscopic analysis, including 1D- and 2D-NMR as well as HR-MS experiments. All compounds showed moderate cytotoxicities against breast cancer (MDA-MB-435S) and lung adenocarcinoma (A549) cell lines, but lacked antifungal activity against Candida albicans. [source] P-Glycoprotein Inhibitory Activity of Two Phenolic Compounds, (,)-Syringaresinol and Tricin from Sasa borealisCHEMISTRY & BIODIVERSITY, Issue 1 2007Hee Jeong Abstract (,)-Syringaresinol and tricin, isolated from the AcOEt-soluble extract of the whole plants of Sasa borealis (Gramineae), showed inhibitory effects on the P-glycoprotein in adriamycin-resistant human breast cancer cells, MCF-7/ADR. [source] Chemistry And Biological Effects Of Dietary Phenolic Compounds: Relevance To Cardiovascular DiseaseCLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 3 2000Lincoln W Morton SUMMARY 1. There has been considerable recent interest in the possibility that increased intake of dietary anti-oxidants may protect against cardiovascular disease. This is partly due to the knowledge that oxidative events in vivo may play a role in the pathogenesis of atherosclerosis. 2. While dietary anti-oxidants, such as vitamins E and C, have received considerable attention in this regard, relatively little is known about a similar anti-oxidant role for plant-derived polyphenolic compounds, such as the flavonoids and phenolic acids. A review of the distribution, bioavailability and biological activity of these compounds suggests that they may have a physiological role as anti-oxidants. 3. Human trials on the anti-oxidant effects of beverages rich in polyphenolics, such as red wine, fruit juice or tea, have been limited and results are, at present, inconclusive. This is due, in part, to poor methodologies available to measure oxidative damage in vivo. 4. There is a sound rationale for considering polyphenolics as important contributors to the dietary anti-oxidant intake derived from fruits and vegetables. However, continuing research is needed using appropriate biomarkers of oxidant damage in vivo before these compounds can be conclusively considered as dietary anti-oxidants with nutritional benefit. [source] Phenolic compounds and some quality parameters of pumpkin seed oilEUROPEAN JOURNAL OF LIPID SCIENCE AND TECHNOLOGY, Issue 2 2010Mirjana Andjelkovic Abstract Pumpkin seed oil has become a recognized source of phenolic compounds. The main aim of this paper was to evaluate the concentration of phenolic compounds and their extraction from pumpkin seed oil. The total phenolics content (TPC) measured in the pumpkin seed oil samples ranged from 24.71 to 50.93,mg GAE/kg of oil. The individual phenolics were tyrosol, vanillic acid, vanillin, luteolin and sinapic acid. Hexane and acetone were the best solvents for the washing step, and methanol for the elution of the phenolics in the solid-phase extraction (diol-SPE), whereas bleaching caused a significant increase in the TPC obtained (24.5,30.7%). Additionally, some other oil characteristics were evaluated. The mean oxidative stability of the oils (OSI) was around 4,h, with 5.43,h for the most stable oil. The maximum antioxidant capacity measured by the reduction of the DPPH radical was 62%, which was comparable to 0.16,mM Trolox equivalent. The color of the oil was expressed by L*a*b* coefficients and its hue and saturation. Whereas all samples had similar lightness, their rates of green, red, yellow and blue color were different. Moreover, TPC correlated negatively with lightness, b* and saturation (,0.49, ,0.48, and ,0.43), and positively with a* and hue (0.58 and 0.52). [source] Contents of Total Phenolics and Ferulic Acid, and PAL Activity during Water Potential Changes in Leaves of Maize Single-Cross Hybrids of Different Drought ToleranceJOURNAL OF AGRONOMY AND CROP SCIENCE, Issue 2 2008T. Hura Abstract The aim of this study was to determine whether the resistance and/or sensitivity to drought stress, can be attributed to the level of phenolic compounds in the leaves of maize genotypes. The experiments were carried out on seedlings of three maize genotypes characterized by different levels of drought resistance. Experiments with three periods of drought were conducted (8, 11 and 14 days), to obtain plants with different levels of water potential in leaves, which induced changes in the total phenolic content and ferulic acid, and l -phenylalanine ammonia-lyase (PAL) activity. Only for the drought-resistant genotype Tina, was the low water potential found to be correlated with the high level of the total phenolic content and ferulic acid, which is the main source of blue fluorescence emissions. Moreover, only for Tina were the highest intensities of blue fluorescence emission correlated with the low water potential in leaves. The phenolic compounds present in leaf tissues can protect the deeper situated mesophyll, by absorbing light reaching the leaf and transforming it into a blue fluorescence. Phenolic compounds can, in this way, function as photoprotectors limiting the excitation of chlorophyll during conditions of water deficit in leaves. [source] PHENOLIC COMPOUNDS IN THE FLESH OF KOREAN APPLE CULTIVAR, BUSAJOURNAL OF FOOD BIOCHEMISTRY, Issue 6 2002HEA-JEUNG WHANG ABSTRACT Phenolic compounds were purified from Busa, the most widely cultivated apple cultivar in Korea, by a sequential separation employing PVPP, Ambertite XAD-2 and Sephadex LH-20 column chromatography. Phenolic compounds in some fractions were farther identified by directly comparing with corresponding phenolic standards after separation on HPLC and GC-MS. The phenolic compounds identified were p-hydoxybenzoic, protocatechuic, 4-hydroxymetyl-benzonic, caffeic, p-coumaric, o-coumaric, ferulic, sinapic and chlorogenic acids and (±)-catechin. Among them, 4-hydroxymethylbenzoic, protocatechuic, o-coumaric and sinapic acids were ascertained as new members of a family of phenolic acids present-in apples. Also the presence of rutin, quercetin and phlorizin in apples were demonstrated using HPLC. [source] Isolation and Characterization of Virgin Olive Oil Phenolic Compounds by HPLC/UV and GC-MSJOURNAL OF FOOD SCIENCE, Issue 4 2001M. Tasioula-margari ABSTRACT This research examined the phenolic fraction of extra virgin olive oil samples from Lianolia variety olives grown in the region of Preveza, Greece. Phenolic compounds were extracted from oil samples, separated by reversed-phase high-performance liquid chromatography (HPLC), and characterized by gas chromatography-mass spectrometry (GC-MS). Both simple and complex phenols were detected with the latter being the most abundant. 3,4-Dihydroxyphenyl ethanol (hydroxytyrosol) and p-hydroxyphenylethanol (tyrosol) predominated among the simple phenols. Complex phenolic compounds were further separated by preparative HPLC and analyzed by GC-MS before and after hydrolysis. The presence of hydroxytyrosol and tyrosol derivatives was confirmed. Both derivatives were always present in greater quantities and made up an average exceeding 70% in all samples analyzed. [source] Studies on Symptom Development, Phenolic Compounds and Morphological Defence Responses in Wheat Cultivars Differing in Resistance to Fusarium Head BlightJOURNAL OF PHYTOPATHOLOGY, Issue 4-5 2002E. SIRANIDOU Abstracts Development of Fusarium head blight, caused by Fusarium culmorum, was evaluated in seven winter wheat cultivars and one spring wheat cultivar in an outdoor pot experiment. Of the cultivars studied, only the spring wheat cultivar Frontana exhibited resistance against initial infection by the fungus. Significantly higher amounts of free phenolic compounds were found in the glumes, lemmas and paleas of Frontana prior to and at all sampling times after inoculation, in comparison to the winter wheat cultivar Agent. Furthermore, the amount of p -coumaric acid increased significantly in the glumes, lemmas and paleas of the cultivar Frontana 2 days after inoculation compared to that in uninoculated spike tissues. However, the amounts of ferulic acid between inoculated and healthy plant tissues did not differ. Ultrastructural studies indicated more pronounced structural defence responses, such as cell wall appositions, in the infected lemma tissue of the resistant cultivar Frontana compared with the susceptible Agent 3 days after inoculation. Immunogold labelling of lignin revealed no differences in the density of gold particles on the cell walls of healthy lemma tissue in the two cultivars. However, density of particles increased in the infected lemma tissue of the resistant cultivar Frontana on cell walls adjacent to the fungal cells, 3 days after inoculation. The susceptible cultivar Agent showed little or no response to the infection. Phenolic compounds appear to play a role in the resistance of the cultivar Frontana to F. culmorum. [source] Walnut (Juglans regia L.): genetic resources, chemistry, by-productsJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 12 2010Marcela L Martínez Abstract Walnut (Juglans regia L.) is the most widespread tree nut in the world. There is a great diversity of genotypes differing in forestry, productivity, physical and chemical nut traits. Some of them have been evaluated as promising and may serve as germplasm sources for breeding. The nutritional importance of the nut is related to the seed (kernel). It is a nutrient-dense food mainly owing to its oil content (up to 740 g kg,1 in some commercial varieties), which can be extracted easily by screw pressing and consumed without refining. Walnut oil composition is dominated largely by unsaturated fatty acids (mainly linoleic together with lesser amounts of oleic and linolenic acids). Minor components of walnut oil include tocopherols, phospholipids, sphingolipids, sterols, hydrocarbons and volatile compounds. Phenolic compounds, present at high levels in the seed coat but poorly extracted with the oil, have been extensively characterised and found to possess strong antioxidant properties. The oil extraction residue is rich in proteins (unusually high in arginine, glutamic and aspartic acids) and has been employed in the formulation of various functional food products. This review describes current scientific knowledge concerning walnut genetic resources and composition as well as by-product obtainment and characteristics. Copyright © 2010 Society of Chemical Industry [source] Nutritional comparison of fresh, frozen and canned fruits and vegetables.JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 6 2007Part 1. Abstract The first of a two-part review of the recent and classical literature reveals that loss of nutrients in fresh products during storage and cooking may be more substantial than commonly perceived. Depending on the commodity, freezing and canning processes may preserve nutrient value. The initial thermal treatment of processed products can cause loss of water-soluble and oxygen-labile nutrients such as vitamin C and the B vitamins. However, these nutrients are relatively stable during subsequent canned storage owing to the lack of oxygen. Frozen products lose fewer nutrients initially because of the short heating time in blanching, but they lose more nutrients during storage owing to oxidation. Phenolic compounds are also water-soluble and oxygen-labile, but changes during processing, storage and cooking appear to be highly variable by commodity. Further studies would facilitate the understanding of the changes in these phytochemicals. Changes in moisture content during storage, cooking and processing can misrepresent changes in nutrient content. These findings indicate that exclusive recommendations of fresh produce ignore the nutrient benefits of canned and frozen products. Nutritional comparison would be facilitated if future research would express nutrient data on a dry weight basis to account for changes in moisture. Copyright © 2007 Society of Chemical Industry [source] Impact of sorghum processing on phytate, phenolic compounds and in vitro solubility of iron and zinc in thick porridgesJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 5 2007AP Polycarpe Kayodé Abstract This study focussed on the impact of process variables on levels of phytate and phenolic compounds, and in vitro solubility of iron (Fe) and zinc (Zn) in sorghum porridges, a major staple in semi-arid tropics. The aim was to identify practices that enhance the mineral availability in this type of staple food. We studied the example of the West African porridge ,dibou' for which the processing methods involve grain cleaning, milling, sieving and cooking. Regional variations occur in the process, particularly in the cleaning which may be done wet or dry; sieving may be omitted in certain locations. Cleaning reduced the phytate content of the grain by 24,39%, while milling, sieving and cooking had no significant effect on phytate. Phenolic compounds measured as levels of reactive hydroxyl groups, remained constant after cleaning, milling and sieving, but significantly decreased by 38,65% after cooking. The Fe solubility tended to increase after cleaning but was drastically reduced due to cooking, and so was the soluble Zn. Levels of total phenolic compounds highly correlated with the Fe and Zn solubility (r2 = 0.73 and 0.82, respectively). Phenolic reaction products formed during the cooking process are presumably related with the extensive browning phenomenon observed in the dibou porridge, and with the reduction observed in Fe and Zn solubility. Copyright © 2007 Society of Chemical Industry [source] Phenolic compounds in some apple (Malus domestica Borkh) cultivars of organic and integrated productionJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 10 2005Robert Veberic Abstract Eleven organically grown apple cultivars and 11 apple cultivars of integrated production from Austria and Slovenia were analyzed by HPLC for the content of phenolic compounds in peel and pulp. We identified chlorogenic acid, p -coumaric acid, procyanidin B3, protocatechuic acid, (,)-epicatechin, phloridzin, rutin and quercetin-3-rhamnoside in apple peel. In apple pulp, (+)-catechin was also identified in all the cultivars. Some other phenols (procyanidin B3, rutin and quercetin-3-rhamnoside) could not be identified or were not properly separated. With regard to the phenolic content in the apple peel, there were no differences between organically grown apple cultivars and apple cultivars of integrated production. Organically grown apples, however, exhibited a higher content of phenolic substances in the apple pulp compared with the apple cultivars of integrated production. This may be due either to the different genotype source or to the growing technology. Higher concentrations of phenolic compounds in organically grown cultivars could be a result of plant response to stress. The apple peel contained higher concentrations of identified phenols than the pulp. The apple peel represents up to 10% of the whole fruit; therefore the phenolsic compounds in the pulp are of greater importance to the consumer than the phenolic compounds in the peel. Copyright © 2005 Society of Chemical Industry [source] Phenolic compounds and the colour of oranges subjected to a combination treatment of waxing and irradiationJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 13 2004Mostafa Moussaid Abstract The effects of waxing, irradiation doses and storage on phenolic compounds and colour of irradiated oranges were investigated. Mature oranges (Citrus sinensis (L) Osbeck var Maroc late) waxed or unwaxed were treated with 0, 1 or 2 kGy radiation and stored up to 9 weeks at 20 °C and 40,50% RH. Colour of the oranges, total phenols and flavones in the peel were measured. Phenolic compounds increased with irradiation dose and storage time. Hue angle, L* value and chroma of the orange colour were more affected by waxing and storage time than the irradiation treatment. Changes in the phenolic compounds were linked with changes in the redness and saturation of the orange colour. Irradiation stimulated synthesis of flavones; waxing controlled changes induced by irradiation. These results may aid in maintaining the quality and safety of oranges during storage. Copyright © 2004 Society of Chemical Industry [source] Phenolic compounds, lycopene and antioxidant activity in commercial varieties of tomato (Lycopersicum esculentum)JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 3 2002Isabel Martínez-Valverde Abstract Nine commercial varieties of tomato (Rambo, Senior, Ramillete, Liso, Pera, Canario, Durina, Daniella and Remate) produced in Spain were analysed for their lycopene content, content of phenolic compounds and antioxidant capacity. The phenolic compounds were characterised as flavonoids (quercetin, kaempferol and naringenin) and hydroxycinnamic acids (caffeic, chlorogenic, ferulic and p -coumaric acids). Antioxidant activity was measured using the DPPH and ABTS assays. The concentrations of lycopene and the various phenolic compounds as well as the antioxidant activity were significantly influenced by the tomato variety. Quercetin, the most abundant flavonoid, was found in concentrations ranging between 7.19 and 43.59,mg,kg,1 fresh weight, while naringenin levels were lower than 12.55,mg,kg,1. The most abundant hydroxycinnamic acid was chlorogenic acid, with values ranging from 14 to 32,mg,kg,1 fresh weight, followed by caffeic acid, while p -coumaric and ferulic acids showed similar concentrations lower than 5,mg,kg,1. The highest content of lycopene was found in Ramillete, Pera and Durina (>50,mg,kg,1 fresh weight), while the concentration in the other varieties was between 50 and 30,mg,kg,1, with the exception of Liso (less than 20,mg,kg,1). The antioxidant activity of tomato extracts varied with the tomato variety and the assay method used. Individual compounds found to be significantly related to antioxidant capacity were lycopene and ferulic and caffeic acids, but not quercetin and chlorogenic acid. © 2002 Society of Chemical Industry [source] Antioxidant and other biological activities of phenols from olives and olive oilMEDICINAL RESEARCH REVIEWS, Issue 1 2002Francesco Visioli Abstract Olive oil is the principal source of fats in the Mediterranean diet, which has been associated with a lower incidence of coronary heart disease and certain cancers. Phenolic compounds, e.g., hydroxytyrosol and oleuropein, in extra-virgin olive oil are responsible for its peculiar pungent taste and for its high stability. Recent findings demonstrate that olive oil phenolics are powerful antioxidants, both in vitro and in vivo, and possess other potent biological activities that could partially account for the observed healthful effects of the Mediterranean diet. © 2001 John Wiley & Sons, Inc. Med Res Rev, 22, No. 1, 65,75, 2002 [source] Properties of wheat bran polyphenol oxidaseMOLECULAR NUTRITION & FOOD RESEARCH (FORMERLY NAHRUNG/FOOD), Issue 1 2004dem Soysal Abstract Polyphenol oxidase (PPO) obtained from wheat bran catalyzed the oxidation of 4-methyl catechol. Phenolic compounds found naturally in crude extract played role as an endogeneous substrate and activity of crude extract needed correction. Activity versus enzyme concentration gave a linear plot at high substrate concentration whereas a nonlinear plot was obtained at low substrate concentration which proved the presence of endogeneous substrate. Adsorption on celite and extraction with polyvinylpyrrolidone (PVPP) caused the removal of phenols. Adsorption of PPO on celite yielded a 4-fold increase in specific activity whereas extraction with PVPP yielded a 2.5-fold increase in specific activity compared to the crude extract. The kinetics of PPO catalyzed oxidation obeyed Michaelis-Menten model; Km and Vmax values were found as 218 mM and 99 ,M/min, respectively. The enzyme was inhibited by ethyl alcohol, dithiothreitol (DTT) and isoproterenol and exhibited heat stability up to a temperature of 90°C. The optimum pH of the enzyme was found to be 5.0. [source] Fluorescence Resonance Energy Transfer Between Polyphenolic Compounds and Riboflavin Indicates a Possible Accessory Photoreceptor Function for Some Polyphenolic CompoundsPHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 5 2006Kumar Chandrakuntal ABSTRACT The photoreceptive extreme tip of the wheat coleoptile exhibits intense green-yellow fluorescence under UV light, suggesting the presence of UV-absorbing materials. Fluorescence spectra of the intact coleoptile tip and tip homogenate showed the presence of the known photoreceptor pigments flavin and carotene, and a preponderance of phenolic compounds. Absorption spectra and fluorescence spectra of various phenolic compounds showed close overlap with the absorption and fluorescence spectra of the wheat coleoptile tip homogenate. Fluorescence spectra of several phenolic compounds showed close overlap with the absorption bands of flavin, carotene and pterine, suggesting possible energy transduction from phenols to these photoreceptors. Excitation of gentisic acid and ferulic acid with 340 nm light in the presence of flavin showed enhancement of flavin fluorescence in a concentration- and viscosity-dependent fashion, indicating fluorescence resonance energy transfer between them and riboflavin. Furthermore, several phenolic compounds tested generated superoxide anion on excitation at 340 nm, suggesting that superoxide-dependent signal cascades could operate in a polyphenol-mediated pathway. Phenolic compounds thus may act as accessory photoreceptors bringing about excitation energy transfer to the reactive photoreceptor molecules, or they may take over the function of the normal photoreceptor in genetic mutations lacking the system, or both processes may occur. The responses of plants to UV-B and UV-A light in mutants may be explained in terms of various phenolics acting as energy transducers in photoreceptor functioning. [source] | ||||||||||||||||||||||||||||||||||