Thèses sur le sujet « Phenol compound »

L'enriquiment de l’oli d'oliva amb els seus propis fenols esdevé una estratègia interessant per augmentar i normalitzar la ingesta diària d’hidroxitirosol sense augmentar el consum calòric. No obstant això, olis amb alt contingut fenòlic proporcionen un gust amarg que podria provocar rebuig entre els consumidors. A més, altes dosis d'hidroxitirosol podria tenir una acció pro-oxidant. En aquesta tesi es va plantejar l'estratègia d'enriquiment d’un oli d'oliva no només amb els seus propis fenols, sinó amb fenols complementaris d'herbes aromàtiques, concretament de farigola, amb la hipòtesi de que apart de proporcionar millores en l'estabilitat de l'oli i l'acceptació dels consumidors, també podria aportar beneficis addicionals per a la salut. Un cop desenvolupat l'oli d'oliva enriquit en fenols, es va avaluar la biodisponibilitat dels fenols mitjançant mètodes in vitro i in vivo, avaluant possibles interaccions o sinergies entre ambdues fonts fenòliques.
El enriquecimiento de aceite de oliva con sus propios fenoles se convierte en una estrategia interesante para aumentar y normalizar la ingesta diaria de hidroxitirosol sin aumentar el consumo calórico. Sin embargo, aceites con alto contenido fenólico tienen un sabor amargo que podría provocar rechazo entre los consumidores, y además sus altas dosis de hidroxitirosol podría tener una acción pro-oxidante. En esta tesis se planteó la estrategia de enriquecimiento de aceite de oliva no sólo con sus propios fenoles, sino con fenoles complementarios de hierbas aromáticas, concretamente tomillo, con la hipótesis de que no sólo podría proporcionar mejoras en la estabilidad del aceite y la aceptación de los consumidores, sino que podría aportar beneficios adicionales para la salud. Una vez desarrollado el aceite de oliva enriquecido se evaluó la biodisponibilidad de los fenoles mediante métodos in vitro e in vivo, evaluando posibles interacciones o sinergias entre ambas fuentes fenólicas.
The enrichment of olive oil with its own phenolic compounds becomes an interesting strategy to increase and standardize the daily intake of hydroxytyrosol without increasing the caloric intake. Concerning olive oils with high phenolic content, however, they have a bitter taste, which could promote a refusal among consumers, and contain high doses of hydroxytyrosol that could have a pro-oxidant action. In this context, the strategy of enriching olive oil not only with its own phenolics but also with complementary phenols from aromatic herbs was outlined in this thesis with the hypothesis that it could not only improve olive oil stability and consumers’ acceptation but also provide additional health benefits. In this thesis a phenol-enriched olive oil was developed using the aromatic herb of thyme, and the bioavailability of the phenolic compounds was assessed, evaluating possible interactions or synergies between both sources through in vitro and in vivo approaches.

Ce memoire presente les syntheses d'acyl-2 methoxy-4 phenols (a) d'alkyl-2 methoxy-4 phenols (b), d'alkyl-3 methoxy -4phenols (c), d'alkoxy-4 phenols (d) d'acide (hydroxy-4' phenyl)-3 methyl-2 propionique (e), d'acide (hydroxy-4' phenyl)-3 hydroxy-2 propionique, d'hydroxy-7 carboxy-3 tetrahydro-1,2,3,4 isoquinoleine et d'acide hydroxy-4 phenylpropargylique(f). L'etude "in vivo" (cobayes) et "in vitro" des proprietes hypopigmentantes des composes a, b, c, d, e et f. L'etude "in vivo" et "in vitro" des proprietes hypopigmentantes de substances naturelles : arbutine, luteoline, abscissine

Thermosets show excellent mechanical properties and chemical resistance (for most automotive fluids) even at high temperatures up to 300 °C. Furthermore they can be highly efficient processed by injection molding. So they should be particularly suited for e.g. under the bonnet applications. However, the reality shows that thermosets are, except fiber reinforced composites, heavily underrepresented in technical applications. E.g. thermosetting components only account 0,2 % to a vehicle’s weight. Therefore reasons can be found in limited knowledge, e.g. relating mold filling behavior. The objective of the study is to analyze the influence of the mold filling behavior during injection molding of highly filled phenolic compounds on mechanical properties. Injection molding filling studies, mechanical testing and optical microscopy were done while varying mold geometry (injection gate and cavity height), mold temperature and injection rate during injection molding a highly filled phenolic compound. It was found that the mold filling behavior varies with altered injection molding parameters as well as the mold geometry. In consequence of this the mechanical properties change according to the resulting reinforcement orientation. The results can help to improve part and mold design for optimal load transmission.

Synthese par une nouvelle methode totalement stereoselective de trans,trans alkyl-3 cyclohexanediols-1,2. Synthese du cis,trans pentadecyl-3 cyclohexanediol-1,2. Activite allergisante et tolerogenique, vis a vis de l'urushiol de ces composes. Approche de la synthese de trans,trans alcenyl-3 cyclohexanediol-1,2. Isolement et structure des principaux composes aromatiques et lipidiques de ginkgo biloba l. Isolement et structure de nouvelles (-) alkyl-3 hydroxy-8 dihydro 3,4 isocoumarines. Isolement et structure de nouveaux nonacosanesdiols. Oxydation en position non activee, par l'acide metachloroperbenzoique des acides anacardiques et des cardanols. Activite allergisante des principaux aromatiques de ginkgo biloba l. Synthese d'un catechol porteur d'un complexe tris-bipyridyle du ruthenium comme sonde de microscopie electronique

Thermosets show excellent mechanical properties and chemical resistance (for most automotive fluids) even at high temperatures up to 300 °C. Furthermore they can be highly efficient processed by injection molding. So they should be particularly suited for e.g. under the bonnet applications. However, the reality shows that thermosets are, except fiber reinforced composites, heavily underrepresented in technical applications. E.g. thermosetting components only account 0,2 % to a vehicle’s weight. Therefore reasons can be found in limited knowledge, e.g. relating mold filling behavior. The objective of the study is to analyze the influence of the mold filling behavior during injection molding of highly filled phenolic compounds on mechanical properties. Injection molding filling studies, mechanical testing and optical microscopy were done while varying mold geometry (injection gate and cavity height), mold temperature and injection rate during injection molding a highly filled phenolic compound. It was found that the mold filling behavior varies with altered injection molding parameters as well as the mold geometry. In consequence of this the mechanical properties change according to the resulting reinforcement orientation. The results can help to improve part and mold design for optimal load transmission.

Thesis (DTech (Chemistry))--Cape Peninsula University of Technology, 2016.
The use of ozone as an advanced oxidation process is gathering wide spread attention with the major limitation to its application being its cost of operation and design considerations. While the general approach of most researches is to buttress the already known fact of the efficacy of the process, little attention is given to studying the by-products of ozone reactions with organics. The aims of this study were to investigate the efficacy of the ozonation process for removing recalcitrant phenolics: phenol, 2-chlorophenol (2CP), 4-chlorophenol (4CP) and 2,4-dichloropheno (2,4DCP) from aqueous medium with a view of understanding various reaction pathways of the process and identifying possible intermediates and residual compounds using liquid chromatography-mass spectrometry (LC-MS). The choice of the selected chlorophenols would also elucidate the role of the positioning of the chlorine atoms in determining reaction rates, pathways and subsequent mechanisms and by-products. Sequel to this, oxy-hydroxy iron in β-phase (β-FeOOH, akaganite) and various β-FeOOH bonded composites on support metal oxides (Al2O3, NiO and TiO2) were prepared via hetero-junction joining, and explored as a possible promoter to improve the efficiency of the ozonation process. Apparent first order reaction rates constants of tested phenolics was in the order 2,4-DCP > 2-CP > Phenol > 4-CP, irrespective of the tested pH. The individual rates however increased with increasing pH. The position 4 chlorine atom was found to be least susceptible to hydroxylative dechlorination. Catechol intermediate and pathway was identified as the major degradation pathway for phenol and 2-CP, while 4-chlorocatechol pathways were more important for 4-CP and 2,4-DCP. The formation of polymeric dimers and trimers by all compounds was pronounced at alkaline pH. Heterogeneous catalytic ozonation using β-FeOOH reduced ozonation time for 4-CP by 32%. Mechanism for β-FeOOH/ozone catalysis showed that the catalyst suffered reductive dissolution in acidic pH and the kinetics of 4-CP removal using the catalyst was best described using a two stage kinetic model. The first stage was attributed to heterogeneous catalysis of ozone breakdown on β-FeOOH surface generating faster reacting radicals, while the second stage was due to homogeneous catalysis by reduced Fe2+ ions in solution. β-FeOOH stabilized on NiO at a 5% ratio exhibited superior catalytic property compared to the other tested composites. Characterization by high-resolution transmission electron microscopy (HRTEM) affirmed a β-FeOOH-NiO bonded interfaced composite which was stable as a iv catalyst over four (4) recycle runs. The mechanism of operation of the composite was via an increased ozone breakdown to radicals as monitored via photoluminescence experiments. The composite material produced satisfactory results when tested on real wastewater samples. Results from this study contribute to the current understanding on reaction mechanisms for ozone with phenols and chlorophenols, for the first time monitoring time captured intermediates via liquid chromatography-mass spectrometric method, which preserves the integrity of reaction intermediates. Also this study proposes heterogeneous catalysts; β-FeOOH and β-FeOOH bonded composites as possible improvements for simple ozone based water purification systems.

This thesis was aimed to analyze phenol oxidation by the bifunctional catalase/phenol oxidase of the thermophilic fungus Scytalidium thermophilum. Several reactive oxygen species (ROS) are continuously produced in fungi under oxidative stress. Depending on the nature of the ROS species, some are highly toxic and are rapidly detoxified by various cellular enzymatic mechanisms, including the production of catalase. S. thermophilum produces a novel bifunctional catalase-phenol oxidase (CATPO) which is capable of oxidizing phenolics in the absence of hydrogen peroxide. Phenol oxidases convert phenolic compounds to quinones, which are then polymerized mainly by free- radical mediated reactions. In this study, 14 phenolic compounds were selected according to their different chemical structures and functional properties and were analyzed as substrates of CATPO. Among 14 phenolic compounds, only in catechol, chlorogenic acid, catechin and caffeic acid distinct oxidation products were observed by HPLC. The oxidation products of catechol, caffeic acid, chlorogenic acid and catechin were characterized by LC-ESI-MS. Dimer, trimer, tetramer and oligomer formations were detected. While the maximum conversion efficiency, at 1 hour of reaction, was observed with catechin, minimum conversion efficiency was attained by caffeic acid, under the specified conditions. The oxidation products observed after oxidation of catechol, chlorogenic acid, catechin and caffeic acid by CATPO was compared with the same phenolic compounds oxidation products oxidized by laccase and tyrosinase. CATPO was incapable of oxidizing tyrosinase and laccase-specific substrates tyrosine and ABTS respectively. However, the oxidizing spectrum of substrates indicates that the nature of phenol oxidation by CATPO appears to resemble mainly those of laccase.

Thesis (MSc (Chemistry and Polymer Science))--University of Stellenbosch, 2009.
ENGLISH ABSTRACT: The separation of apple, cocoa and green tea phenolic compounds by comprehensive 2-dimensional liquid chromatography (2-D-LC) has been studied. In the first dimension, phenolic compounds were separated according to polarity by hydrophilic interaction chromatography (HILIC) on a diol stationary phase with a mobile phase containing acetonitrile, methanol, acetic acid and water. Gradient reversed-phase (RP) LC using a C18 column with fluorescence detection was employed in the second dimension to separate compounds according to hydrophobicity. Compounds were identified using negative electrospray ionisation mass spectrometry (ESI-MS) coupled to both HILIC and RP separations. The coupling of HILIC and RP separations proved to be especially beneficial since this provided simultaneous information on both the polarity and hydrophobicity of phenolics. The low degree of correlation (r2 < 0.21) between the two LC modes afforded peak capacities in excess of 3000 for the off-line method. An on-line method was also developed utilizing a short, small particle-packed column to provide fast separation in the second dimension. A 1 mm i.d. column was used in the first dimension for the on-line system to reduce injection volumes onto the second dimension column. A significantly lower practical peak capacity was measured for the on-line system, due largely to the reduction in second dimension peak capacity. On the other hand, analysis could be performed in an automated fashion using the online system reducing the risk of sample alteration and guaranteeing better operation reliability and reproducibility. Especially the off-line comprehensive HILIC × RP-LC method developed demonstrated its utility in the analysis of various groups of phenolic compounds including proanthocyanidins, phenolic acids, flavonols and flavonol conjugates in a variety of natural products.
AFRIKAANSE OPSOMMING: Die skeiding van fenoliese komponente in appel, kakao en groen tee is deur middel van ‘comprehensive’ 2-dimensionele vloeistof chromatografie (2-D-LC) bestudeer. Hidrofiliese interaksie chromatografie (HILIC) is gebruik om die fenoliese komponente in die eerste dimensie te skei op grond van polariteit, deur gebruik te maak van ‘n diol stationêre fase en mobiele fase bestaande uit asetonitriel, metanol, asynsuur en water. ‘n Gradiënt omgekeerde fase (RP) LC analisie op ‘n C18 kolom met fluorosensie deteksie is in die tweede dimensie gebruik om fenole volgens hidrofobisiteit te skei. Negatiewe elektrosproei-ionisasie massa spektometrie (ESIMS) gekoppel aan HILIC en RP skeidings is gebruik vir identifikasie van fenole. Die koppeling van HILIC en RP skeidings veral voordelig deurdat dit gelyktydige informasie verskaf het oor die polariteit sowel as die hidrofobisiteit van die fenoliese komponente. Die lae graad van korrelasie (r2 < 0.21) tussen die twee LC metodes was verantwoordelik vir piek kapasiteite bo 3000 vir die af-lyn metode. ‘n Aanlyn metode was ontwikkel deur gebruik te maak van ‘n kort, klein partikel gepakte kolom om vinnige skeiding in die tweede dimensie te verseker. 1 mm i.d. kolom was gebruik in die eerste dimensie vir die aanlyn sisteem om die inspuit volume op die tweede dimensie kolom te verminder. Aansienlike laer praktiese piek kapasiteit was gemeet vir die aanlyn sisteem, grootliks toegeskryf aan die reduksie in die tweede dimensie piek kapasitiet. Aan die ander kant, analise kan geoutomatiseerd uitgevoer word deur gebruik te maak van die aanlyn sisteem, wat monster alterasie, beter betroubaarheid en reproduseerbaarhied verseker. Veral die ontwikkelde af-lyn ‘comprehensive’ HILIC × RP-LC metode toon demonstreerbare voordele vir die analiese van verskeie groepe fenoliese komponente, insluitende proantosianiede, fenoliese sure, flavonole en gekonjugeerde flavonole in ‘n verskeidenheid natuurlike produkte.

Thesis (MTech (Chemistry))--Cape Peninsula University of Technology, 2007
The inclusion behaviour of the two host compounds, 9-(4-methoxyphenyl)-9Hxanthen- 9-o1 (A1)• and 9-(4-methylphenyl)-9H-xanthen-9-o1 (A10) were investigated. These host compounds are large, bulky, rigid and they contain functionalities that allow them to selectively interact with other molecules, such as the guests in this work. The host molecules form inclusion complexes with small organic guest molecules. The host•••guest interactions are the interesting focus of this study. The host A1 included the guests: cyclohexane, 1,4-dioxane and N,N-dimethylformamide. Kinetics of desolvation were studied for the 1,4-dioxane and N,N-dimethylformamide compounds. Guest-exchange reactions were performed. The hostA1 was also used in the separation of 1, 4-dioxane and benzene. The host A10 included the guests; benzene, 1,4-dioxane, cyclohexane, cyclohexanone, N,N-dimethylacetamide and N,N-dimethylformamide. Kinetics of desolvation were studied for the benzene and cyclohexane compounds. The host A10 was used in the separation of the following pairs of guests: benzene and 1,4-dioxane; N,N-dimethylformamide and N,Ndimethylacetamide. The structures of the compounds were elucidated using single crystal X-ray diffraction. Thermal analysis was performed in order to determine the thermal stabilities of the complexes, including techniques such as thermogravimetry, differential scanning calorimetry and melting point measurement. The reactions in the guest exchange experiments were monitored using differential scanning calorimetry. Competition experiments were performed to determine the selectivity of a host for a series of related guests. These experiments were conducted between pairs of guests.

Axenic cultures of Chiamydomonas ulvaensis [CCAP 11/58], Scenedesmus brasiliensis [CCAP 276/1 B] and Ochromonas danica [0CAP933/28] were screened for their ability to grow on and remove phenol from their incubation media. Neither C. ulvaensis nor S. brasiliensis removed the phenol substrate as rapidly as 0. danica which is a nutritionally versatile chrysophyte. 0. danica was found to grow on phenol and p-cresol as the sole C-source at concentrations up to 4mM in cultures grown in both photoheterotrophic and heterotrophic conditions. The alga would not grow on cresols or xylenols unless phenol was present. Oxygen uptake and turnover studies confirmed that the enzymes involved in phenolic catabolism were inducible and that the organism showed a decrease in activity resulting from the position and number of the methyl substituents on the aromatic ring. [U- 14C]Phenol was completely mineralised with some 65% of the 14C-label appearing as 14CO2, approximately 12% remaining in the aqueous medium and the rest accounted for in the biomass. Analysis of the biomass showed that 14C-label had been incorporated into the protein, nucleic acid and lipid fractions; phenol carbon is thus unequivocally assimilated by the alga. Phenol-grown cultures of 0. danica converted phenol to catechol which was further metabolised by the meta cleavage pathway. 2-Hydroxymuconic semialdehyde and pyruvate, characteristic products of meta cleavage, were found in incubations of catechol with cell-free extracts of phenol-grown cells together with the appropriate enzyme activities. This is , as far as I am aware, the first definitive identification of the meta cleavage pathway for aromatic ring degradation in a eukaryotic microorganism.

With n-BuLi/t-BuOK (Lochmann's base), protons are removed from the hydroxyl and methyl groups of cresols to give cresol dianions in yields of 85% (o), 95% (m), and 40% (p). These dianions react with alkyl halides, MeSiCl, Bu₃Sn Cl, CO₂, and oxidizing agents at carbon only, and with dialkyl sulfates at both carbon and oxygen. Thus phenol derivatives bearing primary alkyl groups can be prepared from the corresponding methylphenol via cresol dianions. Dimethylphenol trianions were prepared with Lochmann's base from all six isomers of dimethylphenol. 3,5-Dimethylphenol trianion was prepared in the best yield (80%); 2,3-, 2,4-, 2,5-, 2,6-, and 3,4-dimethylphenol trianions were prepared in 19.5%, 19%, 52%, 36%, and 44% yields, respectively. The common side products were dianions and tetraanions (in the latter, the fourth proton was usually pulled from the ring ortho to oxygen). These trianions were reacted with dimethyl sulfate to give anisole derivatives. 3,5-Dimethoxytoluene monoanion was reacted with n-BuBr to give a mixture of O,O'-dimethylolivetol (40%) and 4-butyl-3,5-dimethoxytoluene (34%).

Semiconductor photocatalysis degrades phenolic pollutants to carbon dioxide and water, but the mechanisms of this potentially attractive method of environmental remediation remain unclear. This study aimed to elucidate the primary molecular events by HPLC analysis of the initial products of degradation in water or aqueous acetonitrile. The position of substituents relative to the hydroxyl group were found to influence the reaction rate and also primary oxidation steps, and hence the intermediate profile. 2,6- Dialkylated phenols reacted fastest and showed high conversion to dehydrodimeric products as a prelude to degradation. In contrast, 3,5-dialkylated phenols and 4-tertbutylphenol reacted more slowly and appeared to degrade directly to small polar compounds with little accumulation of primary carbocyclic intermediates. The rate of photocatalytic degradation of two isomeric dibromohydroxybenzonitriles was also influenced by substitution pattern. 3,5-Dibromo-2-hydroxybenzonitrile, however, is itself photolabile in daylight giving 3-bromo-2,5-dihydroxybenzonitrile in aqueous solution. The analogous reaction does not occur for 3,5-dibromo-4-hydroxybenzonitrile, the difference in behaviour being attributed to differences in the electronic spectra of the two compounds. The mechanism of photocatalysis appears to be influenced by the orientation of the substrate on the catalyst surface. For the alkyl phenols, particularly those with tert-butyl substitution, minimisation of disturbance to the polar network of the solvent directs the more hydrophobic parts of the molecule towards the oxidising surface of the catalyst. In addition, this effect encourages clustering of molecules with the subsequent formation of aggregated products. While part of the behaviour observed may be attributable to the presence of acetonitrile in the solvent, the hydrophobic profile of a substrate undergoing heterogeneous photocatalytic oxidation in water would seem to be a significant determinant of the molecular pathway selected in the first phase of its degradation.

Phenolic compounds play a central role in peach fruit colour, flavour and health attributes. Phenolic profiles of several peaches and nectarines and most of the structural genes leading to the anthocyanin synthesis in peach fruit have been studied. Moreover, crosses of red and non-red peaches suggested that a major gene controls skin colour of the extreme phenotypes ‘highlighter’ and ‘full-red’. However, there is no data about either the ‘flavan-3-ols specific genes’ (ANR and LAR) or the regulation of the flavonoid metabolism in this crop. In the present study, we determined the concentration of phenolic compounds in the yellowfleshed nectarine Prunus persica cv. ‘Stark Red Gold’ during fruit growth and ripening. We examined the transcript levels of the main structural genes of the flavonoid pathway. Gene expression of the biosynthetic genes correlated well with the concentration of flavan-3-ols, which was very low at the beginning of fruit development, strongly increased at mid-development and finally decreased again during ripening. In contrast, the only gene transcript which correlated with anthocyanin concentration was PpUFGT, which was high at the beginning and end of fruit growth, remaining low during the other developmental stages. These patterns of gene expression could be explained by the involvement of different transcription factors, which up-regulate anthocyanin biosynthesis (PpMYB10 and PpbHLH3), or repress (PpMYBL2) the transcription of the structural genes. These transcription factors appeared to be involved also in the regulation of the lightinduced anthocyanin accumulation in ‘Stark Red Gold’ nectarines, suggesting that they play a critical role in the regulation of flavonoid biosynthesis in peaches and nectarines in response to both developmental and environmental stimuli. Phenolic profiles and expression patterns of the main flavonoid structural and regulatory genes were also determined for the extreme phenotypes denominated ‘highlighter’ and ‘full-red’ and hypotheses about the control of phenolic compounds content in these fruit are discussed.

Phenolic compounds play a central role in peach fruit colour, flavour and health attributes. Phenolic profiles of several peaches and nectarines and most of the structural genes leading to the anthocyanin synthesis in peach fruit have been studied. Moreover, crosses of red and non-red peaches suggested that a major gene controls skin colour of the extreme phenotypes ‘highlighter’ and ‘full-red’. However, there is no data about either the ‘flavan-3-ols specific genes’ (ANR and LAR) or the regulation of the flavonoid metabolism in this crop. In the present study, we determined the concentration of phenolic compounds in the yellowfleshed nectarine Prunus persica cv. ‘Stark Red Gold’ during fruit growth and ripening. We examined the transcript levels of the main structural genes of the flavonoid pathway. Gene expression of the biosynthetic genes correlated well with the concentration of flavan-3-ols, which was very low at the beginning of fruit development, strongly increased at mid-development and finally decreased again during ripening. In contrast, the only gene transcript which correlated with anthocyanin concentration was PpUFGT, which was high at the beginning and end of fruit growth, remaining low during the other developmental stages. These patterns of gene expression could be explained by the involvement of different transcription factors, which up-regulate anthocyanin biosynthesis (PpMYB10 and PpbHLH3), or repress (PpMYBL2) the transcription of the structural genes. These transcription factors appeared to be involved also in the regulation of the lightinduced anthocyanin accumulation in ‘Stark Red Gold’ nectarines, suggesting that they play a critical role in the regulation of flavonoid biosynthesis in peaches and nectarines in response to both developmental and environmental stimuli. Phenolic profiles and expression patterns of the main flavonoid structural and regulatory genes were also determined for the extreme phenotypes denominated ‘highlighter’ and ‘full-red’ and hypotheses about the control of phenolic compounds content in these fruit are discussed.

The main object of the presented study was investigation of the use of cross-linked enzyme (tyrosinase) aggregates (CLTA) obtained from crude mushroom extract for a rapid phenolic content analysis in wines. In addition, a comparison of phenolic characteristics of Turkish red wines was performed. Reproducible and reliable results in total phenolic measurement were obtained with CLTAs similar to pure tyrosinase and tyrosinase obtained from crude mushroom extract. Measurement of total phenolic content is possible both in standard solutions and in complex matrices, such as wine. In a very short time period, 10 seconds, phenolics content in red and white wines produced from grapes of Turkey were investigated by using CLTAs. Results were consistent when compared to a well known phenolic measurement method, Folin-Ciocalteau. CLTAs exhibited very high operational stability and retained more than 90% of its activity after 30th use. Moreover, it showed good shelf-life stability for about 2 months storage by maintaining 90% of its maximum activity. So, use of CLTAs prepared from crude mushroom extract is an effective, fast and cheap alternative in total phenolics measurements in wines. Moreover, a novel catalase phenoloxidase (CATPO) produced by a fungal microorganism, Scytalidium thermophilum, was studied to check its capabilities in phenolics measurements. This novel catalase phenol oxidase showed similarly good results, exhibiting widesubstrate selectivity.

Diels-Alder [4+2] cycloaddition of a mixture of 1- and 2 methylcyclopentadiene to 2-phenyl-g.-benzoquinone affords a mixture of four nd cycloadducts. A single, isomerically pure cycloadduct was isolated by careful column chromatography. Stereospecific reduction of this material with sodium borohydride and cerium(III) chloride 'affords a single, isomerically pure tricyclic diol. The structures of the cycloadduct and this tricyclic diol, established via analysis of their one- and two-dimensionial NMR spectra, were shown to be (1-methyl-5-phenyltricyclo[6.2.1.02,7]undec a-4,9 diene-3,6-dione and 1-methyl-5-phenyltricyclo[6.2.1.0 2 ,7 ]undeca-4,9-diene t.&A-3-=.a-6-diol), respectively. Intramolecular [2+2] photocyclization of this tricyclic diol afforded the corresponding cage diol, 3-methyl-7phenylpentacyclo[5.4.0.0 2 ,6 .03 , 1 0 .05, 9 ]undecane-.exogxa-8,11-diol. Oxidation of this cage diol with pyridinium chlorochromate in dry dichloromethane afforded a single, isomerically pure cage hydroxyketone, 3-methyl-7 phenylpentacyclo[5.4.02,6.03,l .1519]undecane-xA-8-ol-II-one, whose structure was established by single crystal X-ray crystallographic methods.

The environmental stress cracking (ESC) behaviour of a series of phenolics toughened with varying proportions of thermoplastic (0-35%), has been studied. Since these materials have been designed for applications in 'under-the-bonnet' automotive components, testing took place in serveral 'in-service' environments and in some of the constituent chemicals as well as in air. Initial screening of the materials using three point bend testing highlighted the most hostile environments for further study. Tensile testing of samples in air and in methanol and immersion of samples in various environments provided a further insight concerning the diffusion effects likely to be encountered. Creep tests were conducted in selected environments at 23^oC, as well as at increased temperatures to provide more realistic 'under-the-bonnet' situations. The observed increase in creep rate in most hostile environments was related to crack initiation and growth. Within the range of added thermoplastic studied, two scales of morphology were seen to occur. In addition to a small scale morphology, only observed using TEM, there exists a large scale ribbon-like morphology. This was studied using light microscopy as well as SEM, on samples etched with permanganate and it was shown using X-ray microanalysis that the ribbons visible were thermoplastic rich regions. A good correlation was obtained between the amount of ribbon-like areas and the thermoplastic content of the sample. Samples, apparently prepared under identical conditions, vary slightly in colour. Further investigation revealed that these colour differences could be correlated with a variation in large scale morphology as well as considerable property differences. TEM, SEM and light microscopy were performed to relate the ESC behaviour with the material morphology. TEM investigations concerning the small scale morphology effect upon crack growth were inconclusive. However, from viewing etched samples subject to ESC via bend tests in methanol, using SEM and light microscopy, it was evident that the large scale morphology was responsible for deflecting microcracks.

Doutoramento em Química
Em Portugal, as indústrias corticeira e de pasta de papel constituem um importante sector económico, contudo, gerando elevadas quantidades de subprodutos. Estes subprodutos poderiam ser explorados em aplicações de alto valor acrescentado, como fonte de compostos fenólicos, por exemplo, em vez de serem apenas queimados para produção de energia. Estes compostos são conhecidos pelas suas inúmeras propriedades, entre as quais, antioxidante, anti-inflamatória e anti-trombótica. Neste estudo as frações fenólicas da maior parte dos subprodutos gerados nas indústrias corticeira e de pasta de papel foram caracterizados em detalhe, com vista à sua valorização. A fração fenólica das cascas de Eucalyptus globulus, E. grandis, E. urograndis e E. maidenii, bem como da cortiça de Quercus suber e resíduos provenientes da sua exploração, nomeadamente, o pó de cortiça e os condensados negros, foi obtida por processos convencionais de extração sólido-líquido. No caso da casca de E. globulus, foi ainda avaliado o potencial de metodologias “verdes” no processo de extração de compostos fenólicos, usando extração com CO2 supercrítico. Esta técnica foi otimizada com recurso a metodologias de superfície de resposta. Na identificação e quantificação dos compostos fenólicos foi usada cromatografia líquida de alta resolução aliada a técnicas de espectrometria de massa. O teor de fenólicos totais foi ainda determinado pelo método de Folin- Ciocalteu, essencialmente para efeitos comparativos. A caracterização da fração fenólica de cada extrato foi ainda complementada com a análise da atividade antioxidante, usando o radical 2,2-difenil-1-picrilhidrazilo (DPPH). Foram identificados trinta compostos fenólicos na casca de E. globulus, 17 deles referenciados pela primeira vez como seus constituintes, nomeadamente os ácidos quínico, di-hidroxifenilacétic, cafeico e metil-elágico, bis-hexahidroxidifenoil( HHDP)-glucose, galoil- bis-HHDP-glucose, galoil-HHDPglucose, isoramnetina—hexosídeo, quercetina-hexosídeo, ácido metil-elágicopentosídeo, miricetina-ramnosídeo, isoramnetina-ramnosídeo, mearnsetina, floridzina, mearnsetina-hexosídeo, luteolina e uma proantocianidina B. Neste trabalho, foi estudada pela primeira vez a composição fenólica das cascas de E. grandis, E. urograndis e E. maidenii. Treze, doze e vinte e quatro compostos fenólicos foram identificados nas cascas de E. grandis, E. urograndis e E. maidenii, respetivamente. Entre estes compostos encontram-se os ácidos quínico, gálico, metilgálico, protocatequínico, clorogénico e elágico, catequina, galoil-bis-HHDP-glucose, digaloilglucose, epicatequina, quercetina-glucoronídeo, di-hidroxiisopropilcromona- hexosídeo, isoramnetina-hexosídeo, ácido elágicoramnosídeo, taxifolina, quercetina-hexosídeo, di-hidroxi- (metilpropil)isopropilcromona-hexosídeo, ácido metil-elágico-pentosídeo, miricetina-ramnosídeo, isoramnetina-ramnosídeo, aromadendrina-ramnosídeo, mearnsetina, mearnsetina-hexosídeo, eriodictiol, quercetina, isoramnetina e naringenina. A análise da fração fenólica da cortiça permitiu identificar vinte e dois compostos fenólicos, dez deles referenciados pela primeira vez como seus constituintes, nomeadamente, os ácidos quínico, salicílico, p-hidroxifenillático e metilgálico, ácido carboxílico da brevifolina, eriodictiol, naringenina, um éster isoprenílico do ácido cafeico, isoramnetina-ramnosídeo e isoramnetina. No pó de cortiça industrial foram identificados dezasseis compostos fenólicos, nomeadamente os ácidos quínico, gálico, protocatequínico, cafeico, ferúlico, elágico e metilgálico, esculetina, ácido carboxílico da brevifolina, coniferaldeído, um éster isoprenílico do ácido cafeico, uma dilactona do ácido valoneico, ácido elágico-pentosídeo, ácido elágico-ramnosídeo, isoramnetinaramnosídeo e isoramnetina. Destes, apenas o ácido elágico foi previamente referenciado como componente do pó de cortiça. Do mesmo modo, treze compostos fenólicos foram identificados no condensado negro, doze deles referenciados pela primeira vez como seus constituintes. São eles os ácidos quínico, gálico, p-hidroxifenil-láctico, protocatequínico, p-coumarico, cafeico e elágico, vanilina, esculetina, coniferaldeído, um éster isoprenílico do ácido cafeico e o eriodictiol. A extração supercrítica de compostos fenólicos da casca de eucalipto permitiu não só verificar os parâmetros que afetam a qualidade e quantidade finais dos extratos, como também obter os valores ótimos para estes parâmetros. Esta extração mostrou ainda ser bastante seletiva para determinados grupos de compostos fenólicos, como as flavanonas eriodictiol e naringenina e para o flavonol O-metilado isoramnetina. Este é também o primeiro estudo envolvendo a determinação da atividade antioxidante de extratos da cortiça e dos resíduos da sua exploração, bem como da casca de E. grandis, E. urograndis e E. maidenii. A vasta gama de compostos fenólicos identificados em cada extrato analisado, assim como as prominentes atividades antioxidantes, todas na mesma gama de valores do bem conhecido antioxidante comercial, ácido ascórbico, são claramente um grande contributo para a valorização destes subprodutos industriais.
In Portugal, the cork and the pulp and paper industries are important economic sectors, however, generating substantial amounts of by-products. These byproducts could be exploited in added value applications, rather than being simply burned for energy production, as, for example, as a source of the valuable phenolic compounds. These compounds are known by their innumerous properties, as antioxidant, anti-inflammatory or even antithrombotic. In this study, the phenolic fractions of the most abundant cork and pulp industrial residues were characterised in detail, aiming at up-grading them. The phenolic fraction of the barks of Eucalyptus globulus, E. grandis, E. urograndis and E. maidenii as well as the cork from Quercus suber and the residues of its exploitation, namely, cork powder and black condensates, were obtained by conventional solid-liquid extractions. In the case of E. globulus bark, the potential application of green methodologies in the extraction of phenolic compounds was also evaluated, by using supercritical CO2 extraction. This approach was optimized by using surface response methodology. High-performance liquid chromatography coupled with mass spectrometry techniques were used in the identification and quantification of phenolic compounds. The total phenolic content was also accessed by the Folin- Ciocalteu method, mainly for comparative purposes. The characterization of the phenolic fraction of each extract was also complemented with antioxidant activity measurements, by using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging. Thirty phenolic compounds were identified as constituents of E. globulus bark, 17 of them referenced for the first time, namely, quinic, dihydroxyphenylacetic, and caffeic acids, bis-hexahydroxydiphenoyl(HHDP)-glucose, galloyl-bis- HHDP-glucose, galloyl-HHDP-glucose, isorhamentin-hexoside, quercetinhexoside, methyl-ellagic acid, methyl-ellagic acid (EA)-pentoside, myricetinrhamnoside, isorhamnetin-rhamnoside, mearnsetin, phloridzin, mearnsetinhexoside, luteolin and a proanthocyanidin B-type dimer. The phenolic composition of E. grandis, E. urograndis and E. maidenii bark was studied in this work for the first time. Thirteen, twelve and twenty four phenolic compounds were identified in E. grandis, E. urograndis and E. maidenii bark extracts, respectively. These compounds include quinic gallic, protocatechuic, chlorogenic and ellagic acids, methyl gallate, catechin, galloyl-bis-HHDPglucose, digalloylglucose, epicatechin, quercetin-glucuronide, dihydroxyisopropylchromone- hexoside, isorhamnetin-hexoside, ellagic acid-rhamnoside, taxifolin, quercetin-hexoside, dihydroxy-(methylpropyl)isopropylchromonehexoside, methyl-ellagic acid-pentoside, myricetin-rhamnoside, isorhamnetinrhamnoside, aromadendrin-rhamnoside, mearnsetin, mearnsetin-hexoside, eriodictyol, quercetin, isorhamnetin and naringenin. The analysis of the phenolic fraction of cork allowed to identify twenty two phenolic compounds, ten of them reported for the first times as its constituents, namely, quinic, salicylic and p-hydroxyphenyl-lactic acids, eriodictyol, naringenin, methyl gallate, brevifolin carboxylic acid, caffeic acid isoprenyl ester, isorhamnetin-rhamnoside and isorhamnetin. It were identified sixteen phenolic compounds in industrial cork powder, namely, quinic, gallic, protocatechuic, caffeic, ferulic and ellagic acids and methyl gallate, esculetin, brevifolin carboxylic acid, coniferaldehyde, caffeic acid isoprenyl ester, valoneic acid dilactone, ellagic acid-pentoside, ellagic acid-rhamnoside, isorhamnetinrhamnoside and isorhamnetin. From these, only ellagic acid was previously reported as constituent of cork powder. Likewise, thirteen phenolic compounds were identified on black condensate, twelve of them for the first time, namely quinic, gallic, p-hydroxyphenyl-lactic, protocatechuic, p-coumaric, caffeic and ellagic acids and vanillin, esculetin, coniferaldehyde, caffeic acid isoprenyl ester and eriodictyol. The supercritical extraction of phenolic compounds from E. globulus bark allowed to verify the parameters affecting the qualitatively and quantitatively the final extracts. The optimal conditions of those parameters were obtained. This technique showed to be selective to restrict classes of compounds, such as flavanones and O-methylated flavonols. This was also the first study involving the evaluation of the antioxidant activity of the phenolic extracts of E. grandis, E. urograndis and E. maidenii bark as well as of cork and the residues of their exploitation. The vast range of phenolic compounds identified in each vegetal source studied, as well as its outstanding antioxidant activities, all in the same range of the well known commercial antioxidant ascorbic acid, are, clearly, a contribute to the up-grading of these industrial by-products.

Cysteine plays an important role in many biological and pharmaceutical systems. Therefore, in view of its importance, it is essential to find means of detecting it at the lowest possible levels. In this regard, electrochemical techniques have been found to be capable of detecting analytes even at micro levels. However, electrochemical determination of cysteine occurs at a very high potentials. These overpotentials makes quantitative analysis or detection of cysteine difficult at most conventional carbon electrodes. On platinum electrode, the oxidation of cysteine has been reported to occur in the potential range 0.7 to 1.45 V (vs NHE). Therefore, the object of this investigative study has been to find an active complex that could replace platinum and other expensive metals as electrodes. Such a complex should also be capable of reducing the potential at which the oxidation of cysteine occurs on carbon electrodes. As a result, this manuscript gives a full report on the investigative study of electrocatalytic activity of molybdenum phthalocyanine complexes towards detection of cysteine. Molybdenum phthalocyanine, OMo(OH)Pc, and its tetrasulfonated derivative, [OMo(OH)TSPc]⁴⁻ were successfully used to reduce the potential needed to initiate the oxidation of cysteine on carbon paste electrodes (CPE). The oxidation of cysteine on CPE modified with [OMo(OH)Pc]⁴⁻ was found to occur at 0.29 V (vs Ag/AgCl), and in the presence of [OMo(OH)TSPc]⁴⁻ species in solution the oxidation occurred at 0.33 V (vs Ag/AgCl). Molybdenum, in the oxidation states of Mo(IV), Mo(V) and Mo(VI), is found in biological systems as an essential trace element, participating in a number of enzymatic reactions, where it is believed to be coordinated to sulphur-containing ligands in many molybdenum enzymes. This therefore explains why molybdenum phthalocyanines were employed in electroanalytical detection of sulphur containing amino acid, cysteine. Electrochemical methods have also been successfully used in detection of environmental pollutants such as phenolic compounds. Phenolic compounds are oxidised at readily accessible potentials. However, like cysteine, there are problems associated with the electrochemical detection of these important environmental pollutants. Their electrooxidation is known to form dimeric and/or polymeric oxidation products which adsorb onto the electrode surface, thus -videactivating it. Therefore, to address this problem, cobalt phthalocyanine (CoPc) and its tetrasulfonated derivative, [CoTSPc]⁴⁻ were employed in electrocatalytic detection of phenolic compounds. These complexes were found to increase the anodic peak currents for the oxidation of o-cresol, m-cresol, p-cresol, phenol, 2-chlorophenol and 4-chlorophenol. In addition, CoPc deposited onto the glassy carbon electrode improved the stability of the electrode, by reducing electrode poisoning caused by the electrooxidation products of the mentioned phenolic compounds. The potential at which the oxidation occurred and the current response of individual phenolic compounds depended on the degree of substitution and the type of substituent on the phenol molecule. In general, the current response was found to be lower for chlorinated phenols compared with the cresols and phenol. To establish the role of the central metal in the catalytic process, comparison of the electrocatalytic activity of some of the first row transition metal phthalocyanines, for the detection of mono-substituted phenolic compounds, showed the following trend: Co⁽¹¹⁾ > Mn⁽¹¹⁾ > Fe⁽¹¹⁾Pc > Ni⁽¹¹⁾Pc > Cu⁽¹¹⁾Pc > H₂Pc > Zn⁽¹¹⁾Pc > Bare GCE. A report is also given on electrocatalysis using [CoTSPc]⁴⁻ electrochemically deposited on the glassy carbon electrode. This was also found to enhance the anodic peak currents for the oxidation of all phenolic compounds. A report on the effects of scan rate, operating potential, analyte concentration and other variables is also given.

Oil-bearing plants are important sources of edible oil and proteins; they have attracted attention recently because of their antioxidant, antimicrobial and anti-inflammatory properties. The objective of this work was to investigate the nature of phenolic compounds in oil-bearing plants and the effects of phenolic compounds on protein isolates from soybean and flaxseed. Proteins were isolated from full-fat and defatted soybean and flaxseed using sodium hydroxide extraction and isoelectric precipitation. Free phenolic compounds were extracted from the oil-bearing plants and protein isolates using methanol; for bound phenolic compounds the oil-bearing plants and proteins were subjected to basic and acidic hydrolysis followed by methanol extraction. Total free and bound phenolic compounds were determined by spectrophotometric analysis. Reversed phase-HPLC was used for separation of individual phenolic compounds, which were identified by mass spectrometry (MS). Molecular characteristics and biological properties of the protein isolates were studied using RP-HPLC, polyacrylamide gel electrophoresis (PAGE) and MS. Thermal and gelation properties of protein isolates were investigated using differential scanning calorimetry (DSC) and rheometry. Generally, bound phenolic compounds (20%-30% of total phenolic content) were higher in protein isolates from flaxseed than in protein isolates from soybean (10%-20% of total phenolic content). With flaxseed protein isolates, removal of phenolic compounds showed little effect on the electropherotic behavior of the proteins or the protein subunits. Native-PAGE. SDS-PAGE and RP-HPLC for the peptides profiles of hydrolyzed protein isolates from both full-fat and defatted soybean revealed the removal of free and bound phenolic compounds affect on the biological properties of protein isolates. Removal of free and bound phenolic compounds affected the thermal stability and gelation properties of protein isolates from flaxseed and soybean.

Kyoto University (京都大学)
0048
新制・課程博士
博士(農学)
甲第17626号
農博第1988号
新制||農||1010(附属図書館)
学位論文||H25||N4747(農学部図書室)
30392
京都大学大学院農学研究科農学専攻
(主査)教授 奥本 裕, 教授 白岩 立彦, 教授 松村 康生
学位規則第4条第1項該当

Growing demand and shortages of potable water sources due to industrialization have become a great concern worldwide. Various approaches and solutions have been adopted to provide cleaner and quality water. In a preliminary study, a method of treating wastewater was investigated in which algae were used to remove nutrients (nitrogen and phosphorous) from wastewater and then the algae were harvested for use as a biofuel. The results from this investigation are included in the Appendix B. Employing traditional oxidants, such as hydrogen peroxide, chlorine, and ozone, for treatment of recalcitrant organic compounds have achieved less promising results. However, photocatalysis, an advanced oxidation process (AOP), which is a low-cost and high-efficiency technique, has been widely recognized as a promising approach for water purification and elimination of organic constituents in wastewater. Photocatalysis is the increase in the rate of a chemical reaction by employing a catalyst in the presence of photons. Generally, for a high performance photocatalyst, light of appropriate wavelength is used to activate a catalyst in close contact with contaminants, thereby modifying the rate of the reaction. The presence of these contaminants could pose potential health and environmental concerns, especially in a controlled environment such as on a space station or during long-term manned missions. Thus, the development of energy efficient and "green" technologies to reduce or eliminate organic constituents in wastewater has important potential applications. This research investigated the supported semiconductor photocatalysts (TiO2 and ZnO), particularly ZnO nanorods and nanowires, their synthesis methods, properties and corresponding effectiveness in photocatalysis. The effect of transition metal co-catalysts on the photocatalytic properties of TiO2 was investigated. Although TiO2 is the most extensively studied photocatalyst for water decontamination, ZnO, as presented in this work, could be a substitute because of its lower cost, relative energy bandgap and higher visible light photoactivity. Both photocatalysts were doped and screened for the decomposition of model contaminates, rhodamine B (RhB), phenol and methyl orange, under ultraviolet and/or visible light irradiation. In the photodegradation of RhB, TiO2/Ru 1% showed a superior photocatalytic activity relative to P25-TiO2 under broad-band irradiation, while doped ZnO-Ag resulted in better photodegradation of methyl orange, compared to P25-TiO2, under visible light irradiation. The morphology and estimated chemical composition of photocatalysts were determined by energy dispersive spectroscopy (EDS) and scanning electron microscopy (SEM). Brunhauer, Emmett and Teller (BET) analysis was utilized to measure mass-specific surface area(s). A X-ray diffraction (XRD) study was carried out to confirm the identity of photocatalyst phase(s) present. The cause of low photocatalytic activity under an inert atmosphere, the simple effective fabrication technique of doped ZnO nanowires over TiO2 and properties of the photocatalyst are also discussed.

In this study, extraction of phenolic compounds from sour cherry, peach and apple pomaces using high pressure extraction (HPE) and subcritical CO2 extraction (SCE) was investigated considering total phenolic content (TPC) and antiradical efficiency (AE). Different combinations of pressure (50, 125, 200 MPa), temperature (20, 40, 60&
#61616
C), solid/solvent ratio (0.05, 0.15, 0.25 g/ml) and extraction time (10, 25, 40 min) were used for HPE according to the Box-Behnken experimental design. The variables used for SCE were pressure (20, 40, 60 MPa), temperature (40, 50, 60&
#61616
C), ethanol concentration (14, 17, 20 wt%) and extraction time (10, 25, 40 min). For HPE, TPC and AE at the optimum conditions were 3.80 mg gae/g sample and 22 mg DPPH&
#729
/g sample for sour cherry pomace, 0.93 mg gae/g sample and 6.40 mg DPPH&
#729
/g sample for peach pomace and 2.08 mg gae/g sample and 10.80 mg DPPH&
#729
/g sample for apple pomace, respectively. For SCE, TPC and AE at the optimum conditions were 0.60 mg gae/g sample and 2.30 mg DPPH&
#729
/g sample for sour cherry pomace, 0.26 mg gae/g sample and 1.50 mg DPPH&
#729
/g sample for peach pomace and 0.47 mg gae/g sample and 3.30 mg DPPH&
#729
/g sample for apple pomace, respectively. Efficiency of HPE and SCE methods was compared with solvent extraction (SE). TPC and AE of the extracts obtained by HPE were close to those obtained by SE but the efficiency of SCE was low compared to HPE and SE. SCE was a better extraction method for apple and peach pomaces compared to sour cherry pomace.

The main objective of this study was to extract phenolic compounds from caper and oleaster by using microwave. The effects of microwave power (400 and 700 W), extraction time (5-20 min), solid to solvent ratio (1:10, 1:20 and 1:30) and solvent type (water, ethanol and different ratios of ethanol-water mixture) on total phenolic content, antioxidant activity and concentration of the phenolic compounds in the extracts were investigated. In conventional extraction, extraction time and solvent type were used as independent variables. Microwave extraction was compared with conventional extraction. In caper and oleaster extracts that were obtained by using microwave, total phenolic compounds ranged between 5.0-52.4 and 2.6-43.0 mg GAE/g dry material while the antioxidant activity were between 0.5-2.0 and 0.2-3.7 mg DPPH/g dry material, respectively. Higher total phenolic content was observed with increasing solvent amount. The highest total phenolic content was obtained when 50% ethanol-water mixture was used as solvent. Microwave power did not affect total phenolic content significantly. The highest total phenolic contents were obtained when 400 W microwave power, 50% ethanol-water mixture and solid to solvent ratio of 1:30 were used in the extraction from both caper and oleaster. The best extraction time for caper was 5 min while it was 15 min for oleaster. The main constituents were rutin and kaempferol for both caper and oleaster extracts. For caper and oleaster there was no difference between extraction methods in terms of concentration of phenolic compounds. However, extraction time decreased significantly by using microwave, as compared to conventional extraction.

Raw and processed foods are vulnerable to contamination during their production, distribution and sale. Thus, a wide variety of chemical preservatives are used in the food industry to prevent the growth of food spoilage and pathogenic bacteria. However, health and economic concerns have led to an intensive search for natural alternatives, such as plant extracts, that can safely be used as substitutes for synthetic antimicrobials and preservatives to partially or completely inhibit the growth of bacteria. This study evaluated the antimicrobial effects of natural phenolic compounds extracted from vegetables, fruits, herbs and spices. The main objective was to determine the lowest concentration of phenolics to inhibit the visible growth of the pathogenic bacteria which is defined as the minimum inhibitory concentration (MIC). Some of the most common Gram-positive and Gram-negative foodborne pathogens were treated with several natural phenolic compounds. Concentrations of 5, 10, 15, and 20 ppm (pH 5-6) of each compound were evaluated by broth micro-dilution method and the MICs were determined by using official density (OD) assay. The results demonstrated that the phenolic compounds have varying antimicrobial activities against foodborne pathogens. Natural sources of phenolic compounds contain major antibacterial components and have great potential to be used as natural antimicrobials and food preservatives.

Corynebacterium diphtheriae, Pseudomonas aeruginosa, Ricinus communis, Shigella dysentariae, and Vibrio cholerae produce AB toxins which share the same basic structural characteristics: a catalytic A subunit attached to a cell-binding B subunit. All AB toxins have cytosolic targets despite an initial extracellular location. AB toxins use different methods to reach the cytosol and have different effects on the target cell. Broad-spectrum inhibitors against these toxins are therefore hard to develop because they use different surface receptors, entry mechanisms, enzyme activities, and cytosolic targets. We have found that grape seed extract provides resistance to five different AB toxins: diphtheria toxin (DT), P. aeruginosa exotoxin A (ETA), ricin, Shiga toxin, and cholera toxin (CT). To identify individual compounds in grape seed extract that are capable of inhibiting the activities of these AB toxins, we screened twenty common phenolic compounds of grape seed extract for anti-toxin properties. Three compounds inhibited DT, four inhibited ETA, one inhibited ricin, and twelve inhibited CT. Additional studies were performed to determine the mechanism of inhibition against CT. Two compounds inhibited CT binding to the cell surface and even stripped bound CT off the plasma membrane of a target cell. Two other compounds inhibited the enzymatic activity of CT. We have thus identified individual toxin inhibitors from grape seed extract and some of their mechanisms of inhibition against CT. This work will help to formulate a defined mixture of phenolic compounds that could potentially be used as a therapeutic against a broad range of AB toxins.
M.S.
Masters
Molecular Biology and Microbiology
Medicine
Biotechnology

Le polyuréthane (PU) est le polymère synthétique le plus utilisé dans des applications comme les revêtements, les adhésifs, les élastomères, les mousses et les fibres. De nos jours, la lignine est utilisée dans la synthèse de PU. Une conversion hautement efficace mais peu coûteuse de la lignine est un élément clé de l'utilisation commerciale de la conversion de la biomasse lignocellulosique. L'utilisation de la lignine pour remplacer une partie de polyols en synthèse de polyuréthane suit deux approches principales: (1) utiliser directement de la lignine sans modification chimique préliminaire; (2) utiliser la lignine avec une modification chimique. La lignine modifiée par oxypropylation a été reconnue comme un procédé efficace pour produire des polyols de lignine. En plus de la lignine, d'autres composés qui ont les mêmes groupes fonctionnels que la lignine peuvent être utilisés dans l'industrie de la PU, comme le guaiacol, le phénol et le catéchol. Au cours des dernières décennies la diminution des ressources en combustibles fossiles a suscité des inquiétudes croissantes. La biomasse est considérée comme une matière première potentielle à utiliser largement et à grande échelle grâce à son énorme abondance dans la nature. Parmi les technologies thermochimiques pour l'utilisation des ressources en biomasse, la pyrolyse semble être la plus prometteuse en raison de sa capacité potentielle à permettre aux fabricants commerciaux d'utiliser la biomasse lignocellulosique abondante, économique et locale. Un certain nombre de composés phénoliques préparés par pyrolyse sous vide peuvent être classés en trois groupes présentant les mêmes groupes fonctionnels que le guaiacol, le phénol et le catéchol. Dans ce projet, nous avons d’abord étudié la réaction d'oxypropylation du guaiacol en produisant un produit avec une performance appropriée. Étant donné que le rendement était même inférieur à 3%, la synthèse d'éther de Williamson a été utilisée comme la deuxième méthode pour modifier le guaiacol, le phénol et le catéchol. Le rendement était d'environ 55% à 65%, et les caractérisations étaient également les mêmes que celles habituellement mentionnées dans la littérature pour les polyols compondants.
Polyurethane (PU) is the most wildly used synthetic polymer in many applications like coatings, adhesives, elastomers, foams, and fibers. Nowadays, lignin is used in the synthesis of PU. A highly efficient yet low-cost conversion of lignin is a key element in the commercial utilization of lignocellulosic biomass conversion. Using lignin to replace part of polyols in polyurethane synthesis follows two main approaches: (1) directly using lignin without any preliminary chemical modification; (2) using lignin with chemical modification. Oxypropylation-modified lignin has been recognized as an effective method to produce lignin polyols. In addition to lignin, some other compounds which have the same functional groups as lignin can be used in the PU industry, such as guaiacol, phenol and catechol. The increasingly reduced availability of fossil fuels has caused increasing concerns over the last few decades. Biomass is considered a potential raw material to be used widely and extensively because of its huge abundance in nature. Among the thermochemical technologies for using biomass resources, pyrolysis seems to be the most promising due to its potential capacity to enable commercial-scale plants to use abundant, cheap, and local lignocellulosic biomass. A number of phenolic compounds prepared by vacuum pyrolysis can be classified into three groups bearing the same functionalities as guaiacol, phenol, and catechol. In this project, we have first studied the oxypropylation reaction of guaiacol in producing a product with suitable performance. Since the yield was even less than 3%, Williamson ether synthesis was used as a second method for modifying guaiacol, phenol and catechol. The yield was approximately 55% to 65%, and the characterizations were also the same as usually mentioned in the literature for the corresponding polyols for the compounding polyols.

Mestrado em Engenharia Química
Nos últimos anos, os sistemas aquosos bifásicos (ATPS), utilizando líquidos iónicos, têm revelado um enorme potencial no desenvolvimento de novas técnicas de separação e purificação de biomoléculas, mantendo as suas características funcionais intactas. Neste trabalho, os coeficientes de partição da vanilina e ácido gálico, dois compostos fenólicos com aplicações e propriedades antioxidantes bem conhecidas, foram determinados recorrendo a ATPS envolvendo líquidos iónicos. Foram avaliadas três condições no processo de partição da vanilina: natureza catiónica e aniónica do líquido iónico (LI), a temperatura de equilíbrio e a concentração de vanilina adicionada ao sistema. Todos os parâmetros demonstraram influenciar a partição da vanilina entre as duas fases aquosas. Para obter informação termodinâmica sobre o processo de partição, foram determinadas as funções termodinâmicas molares de transferência da vanilina. Os resultados indicaram que a partição da vanilina resulta essencialmente de um balanço de contribuições entálpicas e entrópicas, onde aniões e catiões mais complexos do LI desempenham um papel crucial. Foram também determinadas duas propriedades termofísicas para estes sistemas, viscosidade e densidade, às mesmas composições às quais se determinaram os coeficientes de partição. Na partição do ácido gálico, foram avaliados diferentes LIs e a influência do pH do meio aquoso por adição de sais inorgânicos distintos. Estes dois parâmetros demonstraram influenciar fortemente a capacidade de extracção dos ATPS estudados. Dada a escassez dos diagramas de fase envolvendo sistemas aquosos de LIs e Na2SO4, os diagramas ternários correspondentes a cada LI, e respectivas tie-lines e comprimentos destas, foram também determinados a 298 K. Em todos os sistemas estudados e em todas as condições testadas, tanto a vanilina como o ácido gálico, mostraram sofrer uma migração preferencial para a fase rica em LI. Com base neste trabalho, pode-se afirmar que os novos ATPS propostos apresentam uma elevada eficiência de extracção para compostos fenólicos constituindo assim uma nova plataforma para processos de separação. ABSTRACT: In recent years, ionic-liquid-based aqueous two-phase systems (ATPS) have been object of great interest due to their potential for the design of new “green” separation processes, in particular for the purification and separation of biomolecules, maintaining their functional characteristics unchanged. In this work, the partition coefficients of vanillin and gallic acid, two well known phenolic compounds, were determined using improved ionic-liquid-based ATPS. Three parameters were evaluated in the vanillin partitioning process: the ionic liquid (IL) cation and anion nature, the temperature of equilibrium and the concentration of vanillin in the system. All parameters have shown to influence the vanillin partitioning. In an attempt to elucidate the thermodynamics of the partitioning process, the standard molar thermodynamic functions of transfer of vanillin were also determined. The results indicated that the partition of vanillin results from an interplay between enthalpic and entropic contributions where both the IL anion and more complex cations play an essential role. Moreover, viscosities and densities of both aqueous phases were experimentally measured at the mass fraction compositions for which the partition coefficients were determined. Regarding the partitioning of gallic acid, different ILs and the influence of the aqueous medium pH, achieved by the addition of distinct inorganic salts, were evaluated. These two parameters have shown to strongly influence the extraction ability by IL-based ATPS. Due to the lack of the ternary phase diagrams compositions containing ILs and the salt Na2SO4, the respective individual phase diagrams, tie-lines and tie-line lengths, were additionally determined at 298 K. In all systems and conditions tested, both vanillin and gallic acid preferentially migrated to the IL-rich phase. The new proposed ATPS present large extraction efficiencies for phenolic compounds and represent a new platform for separation techniques.