Antioxidant properties of sorghum are related to sorghum type and method of processing into foods. Tannin and non-tannin sorghums and their products were evaluated for total phenols, tannins and antioxidant activity. Total phenols were determined using the Folin Ciocalteu method, and tannins were determined by the vanillin-HCl method. Antioxidant activity was evaluated using the ABTS (2,2¢- azinobis(3-ethyl-benzothiazoline-6-sulphonic acid) and DPPH (2,2¢-diphenyl-Ipicrylhydrazyl) assays. Tannin sorghums and their products had higher total phenols, tannins and antioxidant activity than non-tannin sorghum grain and products. Fermentation, extrusion cooking and porridge making reduced measurable phenols, tannins and in vitro antioxidant activity. Reduction was probably due to phenols binding to the food components, thus reducing their solubility in the extracting solvents; 1% HCl in methanol and 70% aqueous acetone. The procyanidin profile obtained using normal phase HPLC and fluorescent detection showed that extrusion cooking and porridge making lowered extractability of polymers (DP>8), while that of oligomers (DP 2-8) and monomers in porridges was not significantly changed. This indicated increased interactions of procyanidin polymers with the food matrix, especially with protein. Pepsin treatment of sorghum extrudates and porridges significantly improved the antioxidant activity and recovery. The highest antioxidant activity was in the supernatants of pepsin hydrolysates. Amylase treatment alone did not significantly affect phenol content and antioxidants, except in bread containing non-tannin white sorghum bran, where there was a slight increase in phenols. The combination of pepsin followed by amylase treatment of porridges and extrudates had effects similar to those of pepsin alone. Improved extractability of antioxidants on pepsin treatment was due to either the release of phenolic antioxidants or protein hydrolysates high in aromatic amino acid residues such as tyrosine, also known for their antioxidant activity. In either situation the improved antioxidant activity could mean that once food is digested it can potentially protect the gastrointestinal tract against oxidative stress generated from the diet and that produced by food interactions during digestion. There is scope to explore other biological methods like use of other proteases to improve antioxidant recovery. Further work would thus determine contribution of phenolic compounds to improved antioxidant activity, and also identify the phenolics.

Phenolic compounds in African green leafy vegetables (GLVs) may have a significant impact on human health. However, there is little information on the phenolic composition, antioxidant properties, as well as biological and cellular protective effects of these vegetables. The effects of boiling and extraction solvent on these compounds and on their antioxidant properties are also unknown. Phenolic content, antioxidant activity and cellular protective effects of four African GLVs in comparison with spinach, an exotic GLV, was determined. African GLVs had appreciable levels of total phenolics and antioxidant activity and in higher quantities compared to spinach. Boiling decreased the antioxidant content and activity of these vegetables and 75% acetone was more effective in extracting antioxidants from the GLVs compared to water. GLVs with high levels of phenolics also contained higher levels of antioxidant activity, suggesting that phenolics are likely to have contributed to radical scavenging activity of these vegetable extracts, even though the degree of scavenging varied in each extract of the vegetable species. The flavonoid compositions of raw and boiled African GLVs and spinach were determined using high-performance liquid chromatography. Epicatechin and rutin were the most dominant flavonoids found in both water and 75% acetone extracts. Among water extracts, pumpkin contained higher concentrations of detected flavonoids, while among the acetone extracts, cowpea exhibited higher concentrations. The effect of boiling was dependent on the type of vegetable and the specific flavonoids. There were no major differences observed between the type of flavonoids detected in extracts of African GLVs and those in spinach. However, similar to the results of total phenolics and antioxidant activity, the 75% acetone extracts of African GLVs also exhibited higher amounts of flavonoids than spinach. The protective effects of GLVs against oxidative haemolysis were dependent on the type of vegetable species. Boiling had variable effects depending on the species. The highest level of protection of erythrocytes against oxidative damage was offered by amaranth extracts, while extracts of raw jute mallow contributed to the damage of erythrocytes. The highest antioxidant protection activity against oxidative damage in plasmid DNA was offered by extracts of jute mallow and lowest by spinach.<p. For the cell viability assays, GLVs were evaluated to determine their cytotoxicity levels and functional role in oxidative damage. The results of the long-term cell viability (i.e. MTT, NR and CV) assays indicated no cytotoxicity, while the short-term cell viability (i.e. DCF) assay indicated that all extracts of raw GLVs were significantly (p < 0.05) cytotoxic to SC-1 fibroblast and human adenocarcinoma colon cancer (Caco-2) cells than extracts of cooked samples, and the levels of toxicity in the extracts of spinach was higher than in African GLVs. These results indicate that there was an initial cytotoxic effect as extracts of raw GLVs were added to the cells. However, after about 72 h, the cells recovered from the initial shock and started proliferating as usual. In the presence of peroxyl radicals, extracts of African GLVs exhibited higher protective effects against oxidative damage in both types of cell cultures than extracts of spinach. These results indicate that these protective effects could be attributed to the presence of phenolics and antioxidant properties of these extracts. Although boiling reduced the antioxidant content and activity of African GLVs, the levels remained higher than in spinach. Boiling also decreased the cytotoxicity and cell damage caused by extracts of raw GLVs samples. African GLVs are consumed after boiling, and therefore the observed cytotoxicities might not be experienced in practical terms. African GLVs have therefore a potential to reduce the risk and development of diseases associated with oxidative stress in communities that consume these vegetables. / Thesis (PhD)--University of Pretoria, 2012. / Centre for Nutrition / PhD / Unrestricted

Les flavonoïdes sont des composés naturels appartenant à la famille des polyphénols, qui sont étudiés depuis de nombreuses années pour leur caractère antioxydant ainsi que leurs propriétés thérapeutique. La mise en évidence, pour certaines d’entre eux, d’une activité vasorelaxante variant en fonction de leur structure, en fait un modèle d’étude de choix pour la prévention des maladies cardiovasculaires. Le 3’,4’-dihydroxyflavonol (DiOHF) est le dérivé le plus décrit pour son fort potentiel en terme de propriétés cardioprotectrices et antioxydantes et est considéré comme un composé d’intérêt dans le traitement anti-ischémique, bien que sa faible solubilité dans l’eau soit un facteur limitant pour son utilisation. Dans ce contexte, notre premier objectif a été de synthétiser une trentaine de dérivés du DiOHF, fonctionnalisés par un groupement hydrophile, tout en préservant ses propriétés antioxydantes et pour certaines des structures obtenues, ses propriétés vasorelaxantes. Pour cela, nous avons développé une méthode de synthèse rapide utilisant les irradiations micro-onde, qui nous a permis d’optimiser les rendements, de réduire les temps de réaction et qui ne conduit à aucune formation de sous-produits. Notre second objectif a été de déterminer l’activité antioxydante de ces dérivés flavonoïques par des tests mettant en œuvre des réactions de compétition avec des radicaux libres. Faisant suite à ce premier screening, des études biologiques chez le rat ont été réalisées sur les composés montrant les meilleures performances. A partir d’essais in vitro et in vivo nous avons démontré, l’innocuité de ces dérivés flavonols, et le fort impact des modifications de structure sur l’activité vasorelaxante et antioxydante, ainsi que sur la récupération fonctionnelle et métabolique consécutive à une ischémie/reperfusion myocardique. Un autre champ d’action de ces flavonols hydrosolubles pourrait être d’explorer leur utilisation dans le traitement du diabète de type 2. Pour cela nous avons greffé deux motifs antidiabétiques, correspondant à des molécules actives déjà utilisées dans le traitement de l’insulinorésistance, sur les dérivés flavonols les plus cardioprotecteurs et/ou vasorelaxants de notre série, ainsi que sur des dérivés de l’acide cinnamique. Ces composés ont été testés pour leur activité antioxydante, laissant supposer un potentiel significativement supérieur aux analogues antidiabétiques non fonctionnalisés, en termes de protection antioxydante et fonctionnelle. / Flavonoids are natural polyphenolic compounds, and epidemiological and pharmacological studies have shown that flavonoids intake is associated with many beneficial effects. An important example is the 3’,4’-dihydroxyflavonol (DiOHF) which showed interesting therapeutic properties in vitro so it could be considered as an important lead compound to the treatment of cardiovascular diseases. However is poor water solubility prevents it use as a drug. Starting from this model we have synthesized a series of new flavones functionalized by a hydrophilic group in order to increase water solubility. To obtain these derivatives we have set up a fast, simple and clean method without formation of by-products, using micro-waves irradiation to optimize yield and to decrease reaction time. Our second purpose was to investigate the antioxidant activity of the synthesized compounds by undergoing several assays. The most promising compounds were tested in biological studies, in vitro and in vivo. The results showed a significant enhancement of the post-ischemic mechanical function recovery in vivo and in vitro. Another purpose was to designed new flavonols linked to selected antidiabetic moieties already used in the treatment of insulinoresistance. It was shown that these new compounds retain the antioxidant properties of the parent flavonols, and can be of interest in the development of new diabete 2 treatments.

As perspectivas são promissoras para a exploração de espécies não tradicionais de frutas tropicais com compostos de interesse nutricional e capacidade antioxidante. Dentre as frutas que apresentam relevantes quantidades de nutrientes, podemos destacar o pequi (Caryocar villosum Alb. Pers.). Na sua forma in natura, possui concentrações expressivas de compostos fenólicos e carotenoides totais, principalmente na polpa, sendo o óleo extraído rico em ácidos graxos. Diversos estudos sobre o cacau relacionam sua alta capacidade antioxidante com sua grande concentração de compostos fenólicos. O objetivo deste estudo foi a utilização do mesocarpo do pequi liofilizado na incorporação em formulação de chocolate amargo com vista à agregação de valor nutricional. No mesocarpo do pequi liofilizado foi verificada a granulometria, biometria, composição centesimal, carotenoides e microscopia eletrônica de varredura. No óleo extraído do mesocarpo do pequi liofilizado foi avaliada a composição em ácidos graxos e colorimetria, bem como a qualidade e funcionalidade nos perfis lipídicos pelos índices de composição: índice de Aterogenicidade (I.A), índice de Trombogenicidade (I.T) e a razão hipocolesterolêmica e hipercolesterolêmica (H.H). Adicionou-se 1,5% de mesocarpo liofilizado na formulação de chocolate amargo determinando-se tamanho de partícula, índice de temperagem, parâmetros físico-químicos, reologia, análise térmica, capacidade antioxidante total pelos métodos de redução do ferro e DPPH, e determinação de fenólicos totais. Como resultado observou-se principalmente a presença dos ácidos graxos palmítíco (26,5 %), oleico (52,67 %) e linoleico (15,2 %) no óleo da polpa. Com a adição de 1,5 % de mesocarpo de pequi liofilizado não houve aumento significativo (p<0,05) do tamanho de partículas da massa do chocolate formulado, não aumentando sua viscosidade e a tensão inicial. A análise de fenólicos totais mostrou um aumento da concentração destes compostos na formulação de chocolate com adição do mesocarpo do pequi liofilizado (813,49 &#181;g GAE.mL -1) em relação à formulação padrão de chocolate amargo (235,98 &#181;g GAE.mL -1), mostrando o grande potencial que este fruto oferece. Na análise de atividade antioxidante, frente ao radical DPPH, houve um aumento da concentração de antioxidantes na formulação de chocolate com adição do mesocarpo do pequi liofilizado (151,65 mg/L) em relação à formulação padrão de chocolate amargo (158,87 mg/L). Na curva de resfriamento da manteiga de cacau encontrou-se o valor BCI (Buhler Crystallization Index) de 3,7 &#177; 0,00, sendo considerado adequado para produção de chocolates. Houve um aumento da temperatura inicial da temperagem e uma diminuição do tempo total do processo com a adição do óleo de pequi na massa do chocolate em relação à formulação controle. A análise térmica indicou que o óleo de pequi suporta temperaturas de até 300 &#176;C, e os chocolates até 50&#176;C. Os índices de funcionalidade do óleo de pequi demostraram que o mesmo possui baixa capacidade de aterogenicidade (0,38), a relação poliinsaturado/ saturado apresentou-se na faixa indicada como benéfica à saúde (0,61), assim como o índice hipocolesterolêmico/ hipercolesterolêmico que se apresentou adequado (2,58). Concluindo-se que houve o aumento no potencial nutricional do chocolate com a adição da polpa de pequi liofilizada, sem alterar estatisticamente suas propriedades reológicas. / The perspectives are promisíng for the exploration of non-traditional species of tropical fruits with compounds of nutritional interest and antioxidant capacity. Among the fruits that present relevant amounts of nutrients, we can highlight pequi (Caryocar villosum Alb. Pers.). In its natural form, it has expressive concentrations of phenolic compounds and total carotenoids, mainly in the pulp, being the extracted oil rich in fatty acids. Several studies about cocoa relate its high antioxidant capacity to its high concentration of phenolic compounds. The objective of this study was the utilization of freeze-dried mesocarp of pequi in the incorporation on bitter chocolate formulation with a view to aggregating nutritional value. In the freeze-dried mesocarp of pequi was verified the granulometry, biometry, centesimal composition, carotenoids and scanning electron microscopy. In the extracted oil of freeze-dried mesocarp of pequi was evaluated the composition of fatty acids and colorimetry, as well the quality and the functionality in the lipids profile by the index of composition: Aterogenicity Index (A.I.), Thrombogenicity Index (T.I.) and hypocholesterolemic and hypercholesterolemic ratio (H.H.). It was added 1.5% of freeze-dried mesocarp in the formulation of bitter chocolate determining particle size, temper index, physico-chemical parameters, rheology, thermal analysis, total antioxidants capacity by reduction of iron and DPPH methods, and determination of total phenolics. As a result, it was observed the main presence of palmitic (26.5%), oleic (52.67%) and linoleic (15.2%) acids in the pulp of the oil. With the addition of 1.5 % of freeze-dried mesocarp of pequi there was no significant increase (p<0.05) in the particle size of the formulated chocolate mass, without increasing its viscosity and initial tension. The analysis of total phenolics showed an increase in the concentration of these compounds in the chocolate formulation with the addition of the freeze-dried mesocarp (813.49 &#181;g GAE.mL-1) in relation to the standard bitter chocolate formulation (235.98 &#181;g GAE.mL-1), showing the great potential that this fruit offers. In the analysis of antioxidant activity, against the radical DPPH, there was an increase in the concentration of antioxidants in the chocolate formulation with the addition of the freeze-dried mesocarp (151,65 mg/L) in relation to the standard bitter chocolate formulation (158.87 mg/L). In the cooling curve of cocoa butter it was found the BCI value (Buhler Crystallization Index) of 3.7 &#177; 0.00 being considered suitable for manufacturing of chocolates. It was occurred an increase of the initial temperature of tempering and a decrease of the total processes time with the addition of pequi Gil in the chocolate mass. The thermal analysis indicated that pequi Gil supports temperatures of up to 300&#176;C, and the chocolates up to 50&#176;C. The functional indexes of pequi Gil showed that it had a low atherogenic capacity (0.38), the polyunsaturated / saturated ratio was in the range indicated as beneficial to health (0.61), as well as the index hypocholesterolemic/ Hypercholesterolemic was adequate (2,58). It was concluded that there was an increase in the nutritional potential of the chocolate with the addition of lyophilized pequi pulp, without statistically altering its rheological properties.

As perspectivas são promissoras para a exploração de espécies não tradicionais de frutas tropicais com compostos de interesse nutricional e capacidade antioxidante. Dentre as frutas que apresentam relevantes quantidades de nutrientes, podemos destacar o pequi (Caryocar villosum Alb. Pers.). Na sua forma in natura, possui concentrações expressivas de compostos fenólicos e carotenoides totais, principalmente na polpa, sendo o óleo extraído rico em ácidos graxos. Diversos estudos sobre o cacau relacionam sua alta capacidade antioxidante com sua grande concentração de compostos fenólicos. O objetivo deste estudo foi a utilização do mesocarpo do pequi liofilizado na incorporação em formulação de chocolate amargo com vista à agregação de valor nutricional. No mesocarpo do pequi liofilizado foi verificada a granulometria, biometria, composição centesimal, carotenoides e microscopia eletrônica de varredura. No óleo extraído do mesocarpo do pequi liofilizado foi avaliada a composição em ácidos graxos e colorimetria, bem como a qualidade e funcionalidade nos perfis lipídicos pelos índices de composição: índice de Aterogenicidade (I.A), índice de Trombogenicidade (I.T) e a razão hipocolesterolêmica e hipercolesterolêmica (H.H). Adicionou-se 1,5% de mesocarpo liofilizado na formulação de chocolate amargo determinando-se tamanho de partícula, índice de temperagem, parâmetros físico-químicos, reologia, análise térmica, capacidade antioxidante total pelos métodos de redução do ferro e DPPH, e determinação de fenólicos totais. Como resultado observou-se principalmente a presença dos ácidos graxos palmítíco (26,5 %), oleico (52,67 %) e linoleico (15,2 %) no óleo da polpa. Com a adição de 1,5 % de mesocarpo de pequi liofilizado não houve aumento significativo (p<0,05) do tamanho de partículas da massa do chocolate formulado, não aumentando sua viscosidade e a tensão inicial. A análise de fenólicos totais mostrou um aumento da concentração destes compostos na formulação de chocolate com adição do mesocarpo do pequi liofilizado (813,49 &#181;g GAE.mL -1) em relação à formulação padrão de chocolate amargo (235,98 &#181;g GAE.mL -1), mostrando o grande potencial que este fruto oferece. Na análise de atividade antioxidante, frente ao radical DPPH, houve um aumento da concentração de antioxidantes na formulação de chocolate com adição do mesocarpo do pequi liofilizado (151,65 mg/L) em relação à formulação padrão de chocolate amargo (158,87 mg/L). Na curva de resfriamento da manteiga de cacau encontrou-se o valor BCI (Buhler Crystallization Index) de 3,7 &#177; 0,00, sendo considerado adequado para produção de chocolates. Houve um aumento da temperatura inicial da temperagem e uma diminuição do tempo total do processo com a adição do óleo de pequi na massa do chocolate em relação à formulação controle. A análise térmica indicou que o óleo de pequi suporta temperaturas de até 300 &#176;C, e os chocolates até 50&#176;C. Os índices de funcionalidade do óleo de pequi demostraram que o mesmo possui baixa capacidade de aterogenicidade (0,38), a relação poliinsaturado/ saturado apresentou-se na faixa indicada como benéfica à saúde (0,61), assim como o índice hipocolesterolêmico/ hipercolesterolêmico que se apresentou adequado (2,58). Concluindo-se que houve o aumento no potencial nutricional do chocolate com a adição da polpa de pequi liofilizada, sem alterar estatisticamente suas propriedades reológicas. / The perspectives are promisíng for the exploration of non-traditional species of tropical fruits with compounds of nutritional interest and antioxidant capacity. Among the fruits that present relevant amounts of nutrients, we can highlight pequi (Caryocar villosum Alb. Pers.). In its natural form, it has expressive concentrations of phenolic compounds and total carotenoids, mainly in the pulp, being the extracted oil rich in fatty acids. Several studies about cocoa relate its high antioxidant capacity to its high concentration of phenolic compounds. The objective of this study was the utilization of freeze-dried mesocarp of pequi in the incorporation on bitter chocolate formulation with a view to aggregating nutritional value. In the freeze-dried mesocarp of pequi was verified the granulometry, biometry, centesimal composition, carotenoids and scanning electron microscopy. In the extracted oil of freeze-dried mesocarp of pequi was evaluated the composition of fatty acids and colorimetry, as well the quality and the functionality in the lipids profile by the index of composition: Aterogenicity Index (A.I.), Thrombogenicity Index (T.I.) and hypocholesterolemic and hypercholesterolemic ratio (H.H.). It was added 1.5% of freeze-dried mesocarp in the formulation of bitter chocolate determining particle size, temper index, physico-chemical parameters, rheology, thermal analysis, total antioxidants capacity by reduction of iron and DPPH methods, and determination of total phenolics. As a result, it was observed the main presence of palmitic (26.5%), oleic (52.67%) and linoleic (15.2%) acids in the pulp of the oil. With the addition of 1.5 % of freeze-dried mesocarp of pequi there was no significant increase (p<0.05) in the particle size of the formulated chocolate mass, without increasing its viscosity and initial tension. The analysis of total phenolics showed an increase in the concentration of these compounds in the chocolate formulation with the addition of the freeze-dried mesocarp (813.49 &#181;g GAE.mL-1) in relation to the standard bitter chocolate formulation (235.98 &#181;g GAE.mL-1), showing the great potential that this fruit offers. In the analysis of antioxidant activity, against the radical DPPH, there was an increase in the concentration of antioxidants in the chocolate formulation with the addition of the freeze-dried mesocarp (151,65 mg/L) in relation to the standard bitter chocolate formulation (158.87 mg/L). In the cooling curve of cocoa butter it was found the BCI value (Buhler Crystallization Index) of 3.7 &#177; 0.00 being considered suitable for manufacturing of chocolates. It was occurred an increase of the initial temperature of tempering and a decrease of the total processes time with the addition of pequi Gil in the chocolate mass. The thermal analysis indicated that pequi Gil supports temperatures of up to 300&#176;C, and the chocolates up to 50&#176;C. The functional indexes of pequi Gil showed that it had a low atherogenic capacity (0.38), the polyunsaturated / saturated ratio was in the range indicated as beneficial to health (0.61), as well as the index hypocholesterolemic/ Hypercholesterolemic was adequate (2,58). It was concluded that there was an increase in the nutritional potential of the chocolate with the addition of lyophilized pequi pulp, without statistically altering its rheological properties.

Tesis por compendio / A pesar de los enormes beneficios potenciales que ofrecen los cítricos genéticamente modificados (GM), su liberación en campo suscita preocupaciones acerca de su potencial impacto ambiental y posibilidad de que muestren efectos deletéreos inesperados desde un punto de vista agronómico. Las principales preocupaciones que plantea el uso de la transformación genética para la mejora de este cultivo de vida larga, propagación vegetativa y compleja biología reproductiva son: (1) la transferencia de los transgenes vía polen a variedades compatibles de especies de Citrus y afines; (2) la estabilidad de los transgenes a largo plazo; (3) la aparición de efectos pleiotrópicos adversos derivados de la integración y la expresión de los transgenes sobre las principales características agronómicas y fenotípicas del cultivo. Todas estas cuestiones han sido ampliamente estudiadas en otros cultivos anuales GM que ya son o no comerciales. Sin embargo, puesto que el empleo de la transformación genética en la mejora de árboles frutales todavía se encuentra en sus inicios, actualmente se dispone de muy poca información al respecto para estos cultivos. Por todo ello, el futuro de los arboles transgénicos en el ámbito comercial permanece aún incierto, aunque actualmente se dispone de la tecnología para producirlos. Por otro lado, en el caso concreto de los cítricos, no existen variedades transgénicas comerciales ni evidencias inequívocas de que esta herramienta sea realmente útil para afrontar con éxito objetivos de mejora concretos. Lograr cumplir objetivos de mejora tan importantes como la mejora de la calidad nutri-funcional de los frutos cítricos mediante ingeniería genética podría contribuir a una mayor aceptación de esta tecnología por parte del público, puesto que se trata de una mejora dirigida primeramente al consumidor. En este trabajo nos hemos planteado afrontar parte de los aspectos que en gran medida limitan la aceptación y comercialización de cítricos GM, mediante (1) la realización de un experimento de campo con cítricos GM para evaluar su seguridad ambiental y la ausencia de efectos agronómicos adversos (2) el abordaje de un objetivo de mejora de la calidad nutri-funcional de la naranja concreto mediante ingeniería metabólica con la finalidad de reforzar sus propiedades saludables. El experimento de campo consistió en una plantación de cítricos transgénicos que portaban únicamente los genes marcadores uidA y nptII cuya finalidad fue estudiar la viabilidad de la transformación genética en la mejora de genotipos cítricos comercialmente importantes. Este huerto experimental nos sirvió para estimar la frecuencia máxima de dispersión de los transgenes por polen bajo condiciones de polinización abierta y estudiar los factores ambientales, genéticos y fenológicos que la determinan, para así poder proponer medidas de contención apropiadas en futuras plantaciones de cítricos GM. También sirvió como primera aproximación para abordar cuestiones básicas como el estudio de la estabilidad de la expresión de los transgenes a largo plazo (tras 7 años de establecimiento en campo) bajo condiciones reales de cultivo y su potencial impacto sobre la morfología, fenología y calidad de la fruta de los cítricos transgénicos. Los estudios realizados, aunque no resuelven todas las preocupaciones concernientes a los cítricos GM, aportan información crucial relativa a su seguridad y comportamiento en campo, inexistente hasta el momento, que puede servir como base para futuros ensayos de campo con cítricos GM y como guía para las políticas de regulación de su plantación (caso-a-caso). Por otro lado, en este trabajo se ha logrado desarrollar una estrategia para inducir producción temprana de fruta e incrementar el contenido de b-caroteno (pro-vitamina A, con elevada capacidad antioxidante) en la pulpa de una variedad de naranjo dulce mediante ingeniería metabólica. Dicha estrategia consistió en el silenciamiento mediado por RNAi del gen de una β-caroteno hidroxilasa de naranjo (CsβCHX), implicada en la conversión de b-caroteno en xantofilas, combinado con la sobreexpresión del gen FLOWERING LOCUS T de naranjo (CsFT) en plantas transgénicas juveniles de naranjo dulce cv Pineapple. Posteriores ensayos con el animal modelo Caenorhabditis elegans demostraron que la naranjas enriquecidas ejercían un efecto antioxidante in vivo un 20% mayor que las naranjas control isogénicas. Este es el primer ejemplo exitoso de ingeniería metabólica para incrementar el contenido de β-caroteno (o cualquier fitonutriente) en naranjas y demuestra el potencial que tiene la ingeniería genética para el enriquecimiento nutricional de cultivos frutales leñosos. / Pons Bayarri, EA. (2014). Towards application of genetic engineering in citriculture: 1) assessing dispersal, long-term stability and phenotypic impact of transgenes in citrus trees and 2) improving nutri-functional quality of orange fruit through metabolic engineering [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/43588 / Compendio

Le fractionnement du bois est un processus faisant appel à des méthodes encore non éco-compatibles. L’étape-clé de ce fractionnement est la délignification, qui utilise des composés chlorés, donc nocifs. Ainsi, des procédés originaux de délignification des sciures de bois de châtaignier ont été développés, utilisant des catalyseurs de type phtalocyanine et porphyrine. Ceux-ci, en milieu oxydant,permettent d’oxyder la lignine et donc de la détruire. Cette délignification a été caractérisée par différentes techniques, notamment par spectroscopie FT-IR et UV-Visible et par la mesure du nombre Kappa. Les résultats se sont révélés globalement décevants mais nous avons tout de même souhaité extraire les 4-O-Méthylglucuronoxylanes (MGX), les hémicelluloses majoritaires du châtaignier, à partir de sciures délignifiées par le système phtalocyanine/H2O2. Ceux-ci ont été extraits par simple traitement à l’eau chaude, ce qui a permis d’obtenir un MGX original porteur de résidu phénolique prouvant la délignification incomplète des sciures. Ces résidus phénoliques confèrent aux MGX un pouvoir antioxydant intéressant mesuré face au radical stable 2,2-diphényl-1-picrylhydrazyl (DPPH) par Résonance Paramagnétique Electronique (RPE) dont la CI50 a été mesuré à 225μg.mL-1, qui, comparé à des références, peut se placer comme un alternatif crédible en tant qu’antioxydant dans l’industrie alimentaire ou cosmétique. Nous avons enfin caractérisé plus précisément un fragment du polysaccharide afin de remonter à sa structure native dans le bois. / Fractionation of wood, essential for the development of its molecular constituents, generally includes non eco-friendly steps. The key-step of the fractionation, the delignification, is generally based on the implementation of aggressive conditions, using harmful reagents, particularly chlorinated. In this work, we developed a new method of delignification of sawdust chestnut, emblematic species of the Limousin region, using phthalocyanine or porphyrin as a catalyst and hydrogen peroxide as the oxidant. Lignin degradation was characterized by various techniques, including FT-IR spectroscopy, UV-visible absorption and by measuring the kappa number. Then we showed that the use of phthalocyanine, less effective that porphyrins in terms of degradation mass yields of lignocellulosic material are however more selective to lignin oxydation. It was then possible, from residues only partially delignified, to extract by a simple hot water a hemicellulose with a similar structure to the 4-O-M¨¦thylglucuronoxylans classically extracted from hardwood. This polysaccharide is characterized by the presence of phenolic residues providing it an interesting antioxidant activity, measured against the radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) by Electron Paramagnetic Resonance (EPR) and its IC50 is estimated at 225¦Ìg. mL-1. This value, compared to reference products such as vitamin E, allows to classify this compound among good candidates for development as a natural preservative for food or cosmetic industries.

La recrudescence des maladies dégénératives ces dernières décennies dans le monde a amené plusieurs chercheurs et médecins à médiatiser les antioxydants à cause des vertus qu’on leur prête: de la protection contre les maladies cardiovasculaires à la prévention de certains cancers. Le présent travail a été mené avec pour objectif principal d’évaluer le pouvoir antioxydant des épices entrant dans la préparation de la sauce en vue du développement d’un complément alimentaire nutraceutique. Pour ce faire, vingt épices largement consommées ont été choisies sur la base d’une enquête exploratoire menée au Cameroun. Les différentes épices réduites en poudres ont été analysées pour leurs teneurs en composition nutritionnelle. Le pouvoir antiradicalaire in vitro des extraits méthanoliques des différentes épices a été déterminé ainsi que le pouvoir anti-inflammatoire et antistress sur des rats adultes à stress induit. Les résultats obtenus ont montré des variations très significatives de la composition des épices. L’activité antioxydante utilisant la méthode au N’ N-diphényl-N’-picrylhydrazyl (DPPH), au « trolox equivalent antioxidant capacity » (TEAC) et le pouvoir réducteur total (PRT) ont révélé que Z. leprieurii et D. glomerata présentent les activités particulièrement élevées. Les extraits de ces deux épices ont servi de base à la préparation de mélange dont l’effet a été testé sur des rats mâles à inflammation induite. Les résultats obtenus ont montré que les épices individuelles et leur mélange à des doses de 100 mg/kg et 150 mg/kg présentent une activité anti-inflammatoire importante comparable à ceux commerciaux: inodméthacine, déxaméthasone et célécoxib. La variation de la teneur en malonaldéhyde (marqueur de l’oxydantion lipidique) a révélée l’action antioxydante in vivo des extraits, démontrant ainsi leur potentiel dans le développement de compléments alimentaires à effet antistress / Increasing evidences from current research point to the fact that certain disease conditions can be prevented through the consumption of antioxidant rich foods. The present work was carried out to evaluate the antioxidant potentials of twenty Cameroonian spices commonly used in some Cameroonian cuisine. The nutritional properties of spices, the in vitro antioxidant potential of their methanolic extracts as well as the in vivo antioxidant potential of the methanolic extracts of some selected samples were determined. The antioxidant activity brought about by N’ N-diphenyl-N’-picrylhydrazyl (DPPH), «trolox antioxidant equivalent capacity» (TEAC) and the total reduction power (PRT) methods have revealed that Z. leprieurii and D. glomerata presented the highest activities. The extracts of the two spices were used to prepare a mixture whose effect was tested on male rats with induced inflammation. The results obtained indicate that the individual spices and their mixture at 100 mg/kg and 150 mg/kg present an important anti-inflammatory activity comparable to that of commercial anti-inflammatory like indomethacin, dexamethasone and celecoxib. The variation of malondialdehyde content (a lipidic oxidant marquer) revealed the in vivo antioxidant action of extracts, thus demonstrating their potential for the development of functional foods with anti-stress effect

В данной работе составлен аналитический обзор литературы по методам определения антиоксидантной емкости. Проведено исследование антиоксидантной емкости экстрактов лекарственных трав и экстрактов виноградного шрота потенциометрическим методом с системой гексацианоферрата калия (III)/ гексацианоферрата калия (II), потенциометрическим титрованием и спектрофотометрическим методом Фолина-Чокальтеу. / In this paper, an analytical review of the literature on the method of determining the antioxidant capacity. A study of the antioxidant capacity of herbal extracts and grape shock extracts by the potentiometric method with the potassium (III) hexacyanoferrate / potassium hexacyanoferrate (II) system, potentiometric titration and the Folin-Chocalteu spectrophotometric method was carried out.

Oxidative stress (OS) plays a critical role in the pathogenesis of atherosclerosis potentially through interaction with nitric oxide (NO) generated by the inducible nitric oxide synthase (iNOS) pathway. Although considerable literature supports a pro-atherogenic role for iNOS-induced NO, recent evidence suggest an anti-atherogenic property for this enzyme where iNOS-induced NO attenuates atherosclerotic lesions after immune injury, enhancing endothelial integrity, survival, protecting against OS-induced apoptosis and necrosis. We therefore hypothesize that iNOS may have a cardio-protective role in the atherosclerotic vessel and that under conditions of OS, expression and function of this enzyme may be impaired, thus contributing to the deleterious consequences of OS. Experiments have therefore been conducted to establish whether pro-oxidants regulate iNOS expression/function in rat cultured aortic smooth muscle cells (RASMCs). These cells were induced for 24 hours with LPS and IFN-γ to mimic inflammatory conditions. Oxidative stress inducers may modulate iNOS-induced NO production through alteration of the expression and/or function of the inducible L-arginine-NO pathway. We examined the effects of hydrogen peroxide (H2O2), antimycin A and diethyl maleate (DEM) on this pathway in vascular smooth muscle cells. H2O2 had little effect on NO production or L-arginine transport while antimycin A and DEM independently caused a concentration dependent inhibition of both processes. Only DEM induced hemeoxygenase-1 (HO-1) expression, monitored by western blotting as a marker of OS. The effects of statins on NO synthesis and L-arginine transport in the presence and absence of OS were also investigated. The benefits of statins therapy in cardiovascular medicine are ascribed in part to their lipid-lowering effect by inhibiting 3-hydroxy-3-methoxyglutaryl coenzyme A (HMG-CoA) reductase, the rate limiting enzyme for cholesterol synthesis. However, statins may possess anti-inflammatory properties and are able to improve endothelial function, stabilize atherosclerotic plaque, and inhibit platelet aggregation, vascular smooth muscle cells proliferation and vessel wall inflammation. These effects may be exerted through novel actions of statins that include interaction with specific signalling pathways in cells which may be associated with the induction of iNOS and/or cationic amino acid transporters (CATs). Thus, we have extended our investigations to include an examination of the effects of statins on both iNOS and CAT function and expression under control conditions and following exposure of cells to OS. Atorvastatin caused a bell shaped response on NO production and iNOS expression and also enhanced L-arginine transport but in a non-concentration dependent manner. Simvastatin only affected NO synthesis without altering transporter activity. Pravastatin was without effect on either system. Further studies demonstrated that that atorvastatin was able to reverse the effects of antimycin A and DEM but only on NO production. These findings confirm that the inducible L-arginine-NO pathway can be downregulated by pro-oxidants. This mechanism may therefore contribute to the deleterious effects observed in disease states associated with OS. Moreover, statins (in particular atorvastatin) appear to be effective in reversing the inhibition of NO production caused by inducers of OS. This, together with the fact that atorvastatin and simvastatin can potentiate iNOS-induced NO production and indeed L-arginine transport (with atorvastatin), highlights a potential novel mechanism through which the cardio-protective actions of these compounds could be mediated.