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Obtenção de extratos de leiteira de dois irmãos (Tabernaemontana catharinensis (A.D.C.), cidrão (Aloysia triphylla L'Herit. Britton) e manga (Mangifera indica L.) por extração supercritica : estudo dos parametros de processo, caracterização e atividade antioxidante dos extratosPereira, Camila Gambini 03 September 2005 (has links)
Orientador: Maria Angela de Almeida Meireles / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-04T02:47:32Z (GMT). No. of bitstreams: 1
Pereira_CamilaGambini_D.pdf: 10935516 bytes, checksum: 3ee55417e7046bcabeb5f38cb0830ef2 (MD5)
Previous issue date: 2005 / Resumo: O resumo poderá ser visualizado no texto completo da tese digital / Abstract: The abstract is available with the full electronic document / Doutorado / Engenharia de Alimentos / Doutor em Engenharia de Alimentos
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ÓLEO ESSENCIAL E INFUSÃO DE Aloysia triphylla: EFEITOS NA ESTABILIDADE DA CARNE DE JUNDIÁ (Rhamdia quelen) / ESSENTIAL OIL AND INFUSION OF Aloysia triphylla: EFFECTS ON STABILITY OF SILVER CATFISH FLESH (Rhamdia quelen)Daniel, Ana Paula 22 August 2014 (has links)
This study has aimed to evaluate the effects of treatments with essential oil (OAT) and infusion of
Aloysia triphylla (IAT) on microbiological, chemical and sensory stability of silver catfish (Rhamdia quelen).
α-citral (29.4%) and β-citral (20.8%) were the main components of OAT, followed by limonene (11.9%).
Major compounds identified in the IAT were isoquercetrin > rosmarinic acid > luteolin. Experiments were
divided in four parts in which the first has was aimed at evaluating the antimicrobial activity of OAT against
foodborne bacteria strains, the microbiological stability of silver catfish fillets refrigerated after dipping in
OAT solution and the microbiological changes during the ice storage of whole silver catfish previously
sedated with OAT during the transport in vivo. In vitro assays revealed that the OAT has strong inhibitory
activity against Staphylococcus aureus and Enterococcus faecalis, and moderate inhibitory activity against
Escherichia coli, Enterobacter aerogenes, Salmonella Typhimurium, Salmonella Choleraesuis and
Salmonella Enteritidis, but does not inhibit Pseudomonas aeruginosa. Fillets imersed in 30 or 40 μL/L of
OAT had lower mesophilic and psychrotrophic counts than control (p<0.05) during storage. Entire refrigerat
fish that were previously sedated with 40 μL/L of OAT slowed lower counts for psychrotrophic at the 7th and
28th days of storage than control (p<0.05), whereas the mesophilic counts were similar to the control during
storage. The 2nd experiment has aimed at determine whether the use of OAT in the water (0, 30 or 40 μL/L)
to sedate silver catfish during transport action would delay the chemical and the sensory post mortem changes
of refrigerated whole fish. Fresheness of entire silver catfish was extented by sedation with 40 μL/L of OAT
as indicated by the delay in the onset of rigor mortis and in the degradation of inosine 5'-monophosphate into
inosine compared to the control (p<0.05). Fish exposed to 30 or 40 μL/L OAT received lower demerit scores
than the control (p <0.05) in sensory evaluation after 10 days of storage, whereas fish treated with 40 μL/L of
OAT had higher shelf life (35 days in ice) than the control (p<0.05). In the 3rd experiment, we assessed
whether the use of OAT in the water to sedate silver catfish during transport would influence the lipid
stability of fish fillets during frozen storage (17 months). The fillets from fish exposed to 30 and 40 μL/L of
OAT had higher initial content of primary products of lipid oxidation (conjugated dienes, CD) than control
fillets, whereas the fillets from fish exposed to 40 μL/L of OAT had lower content of secondary products of
lipid oxidation (thiobarbituric acid reactive substances, TBARS) after 6, 9 and 17 months of frozen storage
than control fillets (p<0.05). The 4th experiment was aimed at evaluating the in vitro antioxidant activity of
IAT and the lipid stability and instrumental color of frozen fillets after immersion in distilled water (control)
or IAT (1, 2.5 or 5%). The antioxidant effect of IAT (1-5%) was demonstrated as the treated fillets had lower
CD values after 7 months of storage, as well as lower TBARS value than control after 4, 7 and 10 months of
storage. Regardeless of the storage time, the treatment with 5% IAT reduced brightness, increased the
yellowness and chroma compared to control fillets, whereas the treatment with 2.5% IAT only increased the
yellowness. However, the total color change during the storage of fillets treated with 2.5 and 5% IAT was
lower than in control fillets (p <0.05). These results indicate that OAT has antimicrobial activity against
foodborne bacteria. Furthermore, the use of OAT as a sedative in the transport of silver catfish extended the
freshness and increased shelf life of the refrigerated whole fish, and also delayed lipid oxidation of the fillets
during frozen storage. Dipping silver catfish fillets in IAT delayed lipid oxidation and color changes during
frozen storage, which can extend the shelf life of fillets. These results indicate the great potential of A.
triphylla in the fish processing sector as a pre-slaughter treatment (sedative) or in the post-slaughter period
(natural food additive). / O objetivo deste estudo foi avaliar os efeitos do óleo essencial de Aloysia triphylla (OAT) e da
infusão de A. triphylla (IAT) na estabilidade da carne de jundiá (Rhamdia quelen) com ênfase nas alterações
microbiológicas, químicas e sensoriais do pescado. O α-citral (29,4%) e o β-citral (20,8%) foram os
compostos majoritários do OAT, seguidos do limoneno (11,9%). Na IAT foram identificados como
compostos majoritários a isoquercetrina > ácido rosmarínico > luteolina. No 1º experimento avaliou-se a
atividade antimicrobiana do OAT contra cepas isoladas de alimentos, a estabilidade microbiológica de filés
refrigerados após imersão em solução de OAT, bem como as alterações microbiológicas durante a
armazenagem sob refrigeração de jundiás inteiros previamente sedados com OAT durante o transporte in
vivo. Os ensaios in vitro revelaram que o OAT apresenta ação inibidora forte contra Staphylococcus aureus e
Enterococcus faecalis, e moderada contra Escherichia coli, Enterobacter aerogenes, Salmonella
Typhimurium, Salmonella Choleraesuis e Salmonella Enteritidis, mas não inibe Pseudomonas aeruginosa.
Os filés imersos em OAT 30 ou 40 μL/L apresentaram menores contagens de micro-organismos mesófilos e
psicrotróficos que o controle (p<0,05) ao longo do armazenamento. Os peixes sedados com 40 μL/L de OAT
durante o transporte tiveram contagens de psicrotróficos menores que o controle após 7 e 28 dias (p<0,05),
enquanto as contagens de mesófilos foram semelhantes ao controle durante o armazenamento. No 2º
experimento foi investigado se o uso do OAT na água (0, 30 ou 40 μL/L) como sedativo durante o transporte
de jundiás pode retardar as modificações químicas e sensoriais do pescado inteiro refrigerado. A exposição
do jundiá a 40 μL/L de OAT durante o transporte retardou o início do rigor mortis, bem como a degradação
de inosina 5´-monofosfato em inosina comparado ao controle (p<0,05), prolongando o frescor do pescado.
Os peixes expostos a 30 ou 40 μL/L de OAT receberam menor escore sensorial de demérito que o controle
(p<0,05) após 10 dias de armazenamento, enquanto os expostos a 40 μL/L de OAT apresentaram maior vida
útil (35 dias em gelo) que o controle (p<0,05). No 3º experimento foi avaliado se o uso do OAT na água
como sedativo durante o transporte de jundiás influencia a estabilidade lipídica dos filés do pescado durante o
congelamento. A exposição 30 e 40 μL/L de OAT resultou em maior teor inicial de produtos primários da
oxidação lipídica (dienos conjugados, DC) nos filés, enquanto os filés dos peixes expostos a 40 μL/L de OAT
apresentaram menor teor de produtos secundários da oxidação lipídica (substâncias reativas ao ácido
tiobarbitúrico, TBARS) que os peixes controle após 6, 9 e 17 meses de congelamento (p<0,05). No 4º
experimento avaliou-se a atividade antioxidante da IAT in vitro e a estabilidade lipídica e cor instrumental de
filés congelados após a imersão em água destilada (controle) ou IAT (1, 2,5 ou 5%). O efeito antioxidante da
IAT (1-5%) foi constatado pelos menores valores DC após 7 meses de congelamento, bem como valor de
TBARS inferior ao controle após 4, 7 e 10 meses de congelamento nos filés tratados. Independente do tempo
de armazenagem, o tratamento com IAT 5% reduziu a luminosidade, aumentou a tendência ao amarelo e o
croma comparado aos filés controle, enquanto o tratamento com IAT 2,5% aumentou apenas a tendência ao
amarelo. No entanto, a variação total de cor dos filés tratados com IAT 2,5 e 5% ao longo do congelamento
foi menor que nos filés controle (p<0,05). Os resultados indicam que o OAT possui atividade antimicrobiana
contra patógenos e micro-organismos indicadores de qualidade dos alimentos. Além disso, a utilização do
OAT como um sedativo na água de transporte de jundiás prolongou o frescor e aumentou a vida útil do
pescado inteiro refrigerado, além de retardar a oxidação lipídica dos filés durante o armazenamento
congelado. A imersão de filés de jundiás na IAT retardou a oxidação lipídica e as mudanças na coloração
durante o armazenamento congelado, podendo estender a vida útil dos filés. Estes resultados indicam o
grande potencial da A. triphylla na área de processamento pescados, tanto no tratamento pré-abate (sedativo)
como pós-abate (aditivo alimentar natural).
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Óleo essencial de aloysia triphylla (l'hérit) britton para jundiás: crescimento, transporte, parâmetros bioquímicos, metabólicos e oxidativos / The essential oil of aloysia triphylla (l'hérit) for silver catfish: growth,trasnport and biochemical, metabolic and oxidative parametersZeppenfeld, Carla Cristina 20 January 2014 (has links)
Conselho Nacional de Desenvolvimento Científico e Tecnológico / The addition of plant extracts in diet led to weight gain in some species fish. The essential oil of Aloysia triphylla (EO) has anesthetic and sedative action for fish and reduces stress handling. Thus, the present study aimed to evaluate the effect of the EO as an additive in animal feed and transportation of silver catfish Rhamdia quelen in relation to growth, intestinal morphology, metabolic and oxidative parameters, In the first experiment, the fish were be divided into three groups: 0 (control), 30 or 40 μL/L EO added to water. The fish were transported in plastic bags for 6 hours and at the end, survival, water quality and ionoregulatory and biochemical parameters were evaluated. In the second were added to the food and different concentrations of OE (0, 0.25, 0.5, 1.0 and 2.0 mL/kg) the growth of silver catfish was observed for 60 days and at the end morphological and immunohistochemical analysis of gut was performed. The addition of EO in the water of transport silver catfish and reduces stress and the suggested concentration is 40 μL /L. The addition of 2.0 mL OE per kg of diet increased in growth and its use is recommended as a feed additive for silver catfish. / A adição de extratos vegetais em rações levaram ao aumento de peso em algumas espécies de peixes. O óleo essencial de Aloysia triphylla (OEA) tem ação anestésica e sedativa para peixes e reduz o estresse de manuseio. Assim, o presente trabalho teve por objetivo avaliar o efeito OEA como aditivo em rações e transporte para jundiás, Rhamdia quelen, em relação ao crescimento, morfologia intestinal, parâmetros metabólicos e estresse oxidativo. No primeiro experimento os peixes foram divididos em três grupos: 0 (controle), 30 ou 40 μL/L adicionado à água OEA. Os peixes foram transportados em sacos plásticos durante 6 horas e ao final foram avaliados: sobrevivência, qualidade da água e parâmetros ionoregulatórios e bioquímicos. No segundo experimento foi adicionada à ração diferentes concentrações de OEA (0; 0,25; 0,5; 1,0 e 2,0 mL/kg), monitorado o crescimento dos jundiás por 60 dias e ao final foi realizada análise morfológica histoquímica do intestino. A adição de OEA na água de transporte de jundiás reduz o estresse e a concentração recomendada é de 40 μL/L. A adição de 2,0 mL/kg de OEA na ração promoveu crescimento e sua utilização é recomendada como um aditivo em alimentos para jundiá.
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Effet protecteur des polyphénols de la verveine odorante dans un modèle d'inflammation colique chez le rat / Protective effect of lemon verbena polyphenols in a model of colonic inflammation in ratsLenoir, Loïc 11 July 2011 (has links)
La consommation de polyphénols, micronutriments largement répandus dans lesaliments d’origine végétale, a été associée à la diminution du risque de développement denombreuses pathologies telles que maladies cardiovasculaires, maladies neurodégénérativesou cancers. Cet effet des polyphénols s’explique en partie par leurs propriétés antioxydanteset anti-inflammatoires. Du fait de leur faible absorption au niveau de l’intestin grêle, lespolyphénols sont présents en grande quantité dans le côlon où ils peuvent exercer cespropriétés. L’inflammation intestinale fait interagir le système immunitaire intestinal avecde nombreux facteurs environnementaux et est fréquemment associée à une augmentationdu stress oxydant via la production d’espèces réactives de l’oxygène par les cellulesimmunitaires. De nombreuses études ont montré, sur des modèles animaux d’inflammationintestinale, les effets protecteurs de certains polyphénols. La verveine odorante (Aloysiatriphylla (L’Hérit.) Britton) est une plante médicinale connue pour ses vertus thérapeutiquesdigestives et anti-spasmodiques et couramment consommée en infusion. L’infusé deverveine odorante contient de grandes quantités de polyphénols (acides phénoliquescomplexes et dérivés de flavones) et ses propriétés antioxydantes ont été mises en évidenceaussi bien in vitro qu’in vivo.L’objectif de cette thèse a donc été d'évaluer l’effet d’une consommation préventived’un infusé de verveine odorante à dose nutritionnelle (40 g/l et 4 g/l) sur le développementd’une inflammation intestinale modérée chez le rat. Des rats Wistar ont consommé commeboisson l’infusé de verveine seul pendant deux semaines puis associé à un agentinflammatoire, le sulfate de dextran sodique (DSS), à 4% pendant 7 ou 9 jours. L’effet de laverveine a été évalué sur différents paramètres cliniques (diarrhée, saignements rectaux,poids corporel), marqueurs de l’inflammation (longueur du côlon, score histologique,activité myéloperoxydase, cytokines) et du stress oxydant (peroxydation lipidique,glutathion, défenses antioxydantes enzymatiques). Les cellules immunitaires ont étéidentifiées dans le sang ainsi que dans les structures lymphoïdes secondaires par cytométrieen flux. Enfin l’étude du métabolisme des polyphénols en situation inflammatoire ou non aété initiée par l’analyse de l’excrétion urinaire des dérivés polyphénoliques.Lors d’une inflammation de 7 jours, la consommation préventive d’infusé deverveine à 40 g/l et 4 g/l retarde l’apparition de diarrhée et de saignements rectaux, limite larétraction du côlon et la diminution de la prise de poids des rats. Malgré l’absence d’effetsur l’activité myéloperoxydase, l’infusé à 40 g/l atténue les altérations histologiques de lamuqueuse colique induites par l’inflammation. L’infusé à 4 g/l stimule l’activité de lasuperoxyde dismutase et réduit la peroxydation lipidique. Les deux infusés modulent lespopulations de cellules immunitaires dans les structures lymphoïdes secondaires (ganglionsmésentériques et plaques de Peyer), en particulier les lymphocytes B et les lymphocytes Tcytotoxiques. L’excrétion urinaire des polyphénols de la verveine est faible et n'est pasaffectée par l'inflammation. Lors d’une inflammation de 9 jours, les deux infusés limitentl’augmentation d’activité de la myéloperoxydase. Seul l’infusé à 40 g/l limite la rétractiondu côlon, stimule l’activité de la glutathion réductase et diminue les taux d’IL-6 et deTNF-α. Ainsi, nous avons montré qu’une consommation préventive d’un infusé de verveineodorante offre des effets protecteurs lors de l’inflammation intestinale en agissant àdifférents niveaux. L’exploration des voies de signalisation impliquées pourrait permettre demieux comprendre les effets protecteurs de cette boisson de consommation courante. / Polyphenols are micronutrients widely distributed in foods of plant origin and theirconsumption has been associated with a decreased risk of various pathologies such ascardiovascular diseases, neurodegenerative diseases and cancer. This effect of polyphenolsis sustained by their antioxidative and anti-inflammatory properties. Due to their poorabsorption in the small intestine, high amounts of polyphenols reach the colon where theycan exert such properties. Intestinal inflammation results from an interaction between gutimmunity and various environmental factors and is frequently associated with an increase ofoxidative stress. Numerous studies have shown protective effects of polyphenols in animalcolitis models. Lemon verbena (Aloysia triphylla (L’Hérit.) Britton) is a medicinal herbknown for its digestive and antispasmodic properties and is widely consumed as an infusion.Lemon verbena infusion contains large amounts of polyphenols (complex phenolic acidsand flavone glycosides) and their antioxidative properties have been shown in vitro and invivo.The aim of the present thesis was to evaluate the effects of a preventive consumptionof lemon verbena infusion at nutritional doses (40 g/l and 4 g/l) on the development of amoderate colitis in the rat. Wistar rats ingested lemon verbena infusion alone as a drink fortwo weeks and then associated with the inflammatory agent dextran sulfate sodium (DSS) at4% for 7 or 9 days. Effects of lemon verbena were evaluated on several clinical parameters(diarrhoea, rectal bleeding, body weight), inflammatory markers (colon length, histologicalscore, myeloperoxidase activity, cytokines) and oxidative stress markers (lipid peroxidation,glutathione, antioxidative enzymatic defenses). Immune cells were identified in blood andgut associated lymphoid structures using flow cytometry. Moreover, the study of polyphenolmetabolism was initiated by the analysis of urinary polyphenol metabolites in healthy andcolitis rats.During a 7 days inflammation, the preventive consumption of lemon verbenainfusion at 40 g/l and 4 g/l delays apparition of diarrhoea and rectal bleeding, limits thecolon length reduction and the decrease of body weight gain. Despite no effect onmyeloperoxidase activity, the 40 g/l infusion attenuates colonic mucosa alterations due tothe colitis. The 4 g/l infusion increases superoxide dismutase activity and reduces lipidperoxidation. Both infusions modulate immune cell populations in gut associated lymphoidstructures (mesenteric lymph nodes and Peyer patches), especially B cells and cytotoxic Tcells. Urinary excretion of lemon verbena polyphenols is low and not modified byinflammation. During a 9 days inflammation, both lemon verbena infusions limitmyeloperoxidase increase. Only the 40 g/l infusion reduces colon retraction, increasesglutathione reductase activity and reduces colonic IL-6 and TNF-α levels.Thus, we have shown that the preventive consumption of a lemon verbena infusionprovided protection against intestinal inflammation at different levels. Exploration ofvarious signalling pathways could allow better insight into the protective effects of thiscommon beverage.
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Evaluación de la Actividad Antibacteriana in vitro del Aceite Esencial de Hojas de Aloysia triphylla P. “Cedrón” Frente a Escherichia coli ATTC 25922 y Staphylococcus aureus 25923Aliaga Mamani, Patricia Alexandra 23 October 2013 (has links)
El presente trabajo se realizó con el fin de evaluar la actividad antibacteriana in vitro del aceite esencial de hojas de Aloysia triphylla P. “cedrón” de la región de Tacna, frente a las bacterias patógenas Escherichia coli ATCC 25922 y Staphylococcus aureus ATCC 25923. Se determinó la sensibilidad antibacteriana de Escherichia coli y Staphylococcus aureus, por el método de disco difusión, por el método de dilución en medio líquido y difusión en agar. Los resultados indican que el aceite esencial, contiene actividad antibacteriana significativa frente a Escherichia coli y moderada frente a Staphylococcus aureus. Así, el estudio reveló la CMI de Escherichia coli siendo de 3,701 mg/mL mientras que para Staphylococcus aureus fue 15,167 mg/mL (dosis cinco veces mayor). También se precisó la CMB de Escherichia coli siendo de 4,186 mg/mL, mientras que para Staphylococcus aureus fue 16,259 mg/mL (dosis cuatro veces mayor).
Palabras claves: Sensibilidad antibacteriana, CMI, CMB, Escherichia coli ATTC 25922, Staphylococcus aureus ATCC 25923.
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Avaliação do eugenol e de óleos essenciais na redução do estresse em aquicultura / Evaluation of the stress-reducing effect of eugenol and essential oils on aquacultureParodi, Thaylise Vey 07 January 2014 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This study evaluated the anesthetic efficacy of eugenol and essential oils (EOs) of Aloysia
triphylla and Lippia alba on aquaculture, as well as their stress-reducing effect during
transport of shrimp and fish. The effectiveness of eugenol on blocking noxious stimulis
was also tested. Sub-adult and post-larvae of white shrimp (Litopenaeus vannamei), albine
and grey silver catfish (Rhamdia quelen) and fat snook (Centropomus paralellus) were
evaluated for anesthetic induction time and recovery during short and long exposure to the
EOs and eugenol. Oxidative stress parameters were also evaluated in sub-adult shrimps.
Both silver catfish strains and fat snook were transported in water containing EO of A.
triphylla at different concentrations and the reduction of stress was evaluated. An
experimental model was elaborated to test the analgesic activity of eugenol in zebrafish
(Danio rerio). The concentrations of eugenol, EO of A. triphylla and L. alba recommended
for anesthesia in shrimps were respectively 200, 300 and 750 μL L-1 for sub-adults and
175, 300 and 500 μL L-1 for post-larvae. The concentrations indicated for transport are
between 20-50, 20-30 and 50 μL-1 for sub adults and for post-larvae only eugenol and EO
of A. triphylla at 20 and 20-50 μL L-1. A better antioxidant capacity in the hemolymph was
obtained with 30 μL L-1 EOs of A. triphylla and L. alba and 20 μL L-1 eugenol. Albine silver
catfish juveniles induced and recovered form anesthesia in longer time than grey ones and
200 μL L-1 was considered the most suitable concentration for both strains. In the transport
the OE de A. triphylla increased whole body cortisol but did not promote ion loss. The
increase of the concentration of OE A. triphylla proportionately decreased and increased
the time of induction and recovery from anesthesia in fat snooks. The concentration of 20
μL L-1 reduced blood glucose levels after 24 h and plasma cortisol and lactate levels after
6h. Eugenol itself did not presented analgesic activity, but after the injection of acetic acid
in the anterior portion eugenol blocked the noxious reflex. / O trabalho objetivou avaliar a eficácia anestésica do eugenol e óleos essenciais (OEs) de
Aloysia triphylla e Lippia alba em aquicultura, bem como a eficácia dos mesmos como
redutores de estresse durante o transporte de camarões e peixes e verificar efeito
bloqueador de estímulos nocivos do eugenol. Camarões (sub-adultos e pós larvas),
ambas variedades de jundiá e robalos-peva foram transportados em água contendo óleo
essencial de A. triphylla em diferentes concentrações e avaliada a redução do estresse.
Para eugenol foi traçado modelo experimental de avaliação da atividade analgésica em
peixe-zebra (Danio rerio). As concentrações de eugenol e OE de A. triphylla e L. alba
recomendadas para anestesia em camarões foram, respectivamente de 200, 300,750 μL
L-1 para sub-adultos e para pós-larvas 175, 300 e 500 μL L-1. Para transporte
concentrações entre 20-50; 20-30 e 50 μL L-1 são apropriadas para sub-adultos e para
pós-larvas somente eugenol e OE de A. triphylla 20 e 20-50 μL L-1. Uma melhor
capacidade antioxidante na hemolinfa de camarões foi obtida com 30 μL L-1 OEs de A.
triphylla e L. alba e 20 μL L-1 para eugenol. Juvenis albinos de jundiá induziram e
recuperaram da anestesia em maior tempo que os cinzas e considerou-se 200 μL L-1 a
concentração mais adequada. No transporte, embora o OE de A. triphylla tenha causado
aumento de cortisol corporal em jundiás, houve redução da perda de íons. Em robalospeva
o aumento da concentração do OE de A. triphylla proporcionalmente diminuiu e
aumentou o tempo de indução e recuperação anestésica, respectivamente. A
concentração de 20 μL L-1 reduziu os níveis de glicose sanguínea após 24h e de cortisol e
lactato após 6h. O eugenol por si só não apresentou atividade analgésica, porém quando
injetado ácido acético na porção anterior de zebrafish a resposta ao efeito nocivo foi
bloqueada.
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Effet protecteur des polyphénols de la verveine odorante dans un modèle d'inflammation colique chez le ratLenoir, Loïc 11 July 2011 (has links) (PDF)
La consommation de polyphénols, micronutriments largement répandus dans lesaliments d'origine végétale, a été associée à la diminution du risque de développement denombreuses pathologies telles que maladies cardiovasculaires, maladies neurodégénérativesou cancers. Cet effet des polyphénols s'explique en partie par leurs propriétés antioxydanteset anti-inflammatoires. Du fait de leur faible absorption au niveau de l'intestin grêle, lespolyphénols sont présents en grande quantité dans le côlon où ils peuvent exercer cespropriétés. L'inflammation intestinale fait interagir le système immunitaire intestinal avecde nombreux facteurs environnementaux et est fréquemment associée à une augmentationdu stress oxydant via la production d'espèces réactives de l'oxygène par les cellulesimmunitaires. De nombreuses études ont montré, sur des modèles animaux d'inflammationintestinale, les effets protecteurs de certains polyphénols. La verveine odorante (Aloysiatriphylla (L'Hérit.) Britton) est une plante médicinale connue pour ses vertus thérapeutiquesdigestives et anti-spasmodiques et couramment consommée en infusion. L'infusé deverveine odorante contient de grandes quantités de polyphénols (acides phénoliquescomplexes et dérivés de flavones) et ses propriétés antioxydantes ont été mises en évidenceaussi bien in vitro qu'in vivo.L'objectif de cette thèse a donc été d'évaluer l'effet d'une consommation préventived'un infusé de verveine odorante à dose nutritionnelle (40 g/l et 4 g/l) sur le développementd'une inflammation intestinale modérée chez le rat. Des rats Wistar ont consommé commeboisson l'infusé de verveine seul pendant deux semaines puis associé à un agentinflammatoire, le sulfate de dextran sodique (DSS), à 4% pendant 7 ou 9 jours. L'effet de laverveine a été évalué sur différents paramètres cliniques (diarrhée, saignements rectaux,poids corporel), marqueurs de l'inflammation (longueur du côlon, score histologique,activité myéloperoxydase, cytokines) et du stress oxydant (peroxydation lipidique,glutathion, défenses antioxydantes enzymatiques). Les cellules immunitaires ont étéidentifiées dans le sang ainsi que dans les structures lymphoïdes secondaires par cytométrieen flux. Enfin l'étude du métabolisme des polyphénols en situation inflammatoire ou non aété initiée par l'analyse de l'excrétion urinaire des dérivés polyphénoliques.Lors d'une inflammation de 7 jours, la consommation préventive d'infusé deverveine à 40 g/l et 4 g/l retarde l'apparition de diarrhée et de saignements rectaux, limite larétraction du côlon et la diminution de la prise de poids des rats. Malgré l'absence d'effetsur l'activité myéloperoxydase, l'infusé à 40 g/l atténue les altérations histologiques de lamuqueuse colique induites par l'inflammation. L'infusé à 4 g/l stimule l'activité de lasuperoxyde dismutase et réduit la peroxydation lipidique. Les deux infusés modulent lespopulations de cellules immunitaires dans les structures lymphoïdes secondaires (ganglionsmésentériques et plaques de Peyer), en particulier les lymphocytes B et les lymphocytes Tcytotoxiques. L'excrétion urinaire des polyphénols de la verveine est faible et n'est pasaffectée par l'inflammation. Lors d'une inflammation de 9 jours, les deux infusés limitentl'augmentation d'activité de la myéloperoxydase. Seul l'infusé à 40 g/l limite la rétractiondu côlon, stimule l'activité de la glutathion réductase et diminue les taux d'IL-6 et deTNF-α. Ainsi, nous avons montré qu'une consommation préventive d'un infusé de verveineodorante offre des effets protecteurs lors de l'inflammation intestinale en agissant àdifférents niveaux. L'exploration des voies de signalisation impliquées pourrait permettre demieux comprendre les effets protecteurs de cette boisson de consommation courante.
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