There are two purposes in this research, one is to develop the new method which can be used for detection and quantification of chloramphenicol in fish, and the method is according to Commission Decision 2002/657/EC. The other is to study about the depletion of chloramphenicol in Tilapia which is the main aquacultural product in Taiwan. Homogenized fish tissues were extracted with EtOAc and defatted with Hexane. HPLC separation was conducted on RP18 column in 0.5mM ammonium acetate ¡V MeOH. Chloramphenicol was determinated by LC-ESI-MS-MS in negative mode. The recoveries of chloramphenicol from fish gill, gut, liver and muscle were 68.8, 73.3, 82.7 and 85.5%. The limit of detection was 0.05, 0.14, 0.07 and 0.03 ng/g. Decision limit(CC£\) of fish muscle was 0.05 ng/g and detection capability(CC£]) was 0.07 ng/g. Chloramphenicol was administered by oral and by bathing respectively in Tilapia. Chloramphenicol was given by bathing at 45.8 mg/kg for one hour. No chloramphenicol was demonstrated in gill, gut and fish muscle on 193th hour, 673th hour, and 385th hour respectively after the beginning of this study. There was 0.08 ng/g chloramphenicol in liver after 385th hour. Chloramphenicol was given orally to Tilapia at 354.5 mg/kg daily for 3 days. No chloramphenicol demonstrated in fish muscle on 480th hour. There were 0.09 ng/g and 0.16 ng/g in liver and gut respectively. No matter oral experiment or bathing experiment, th concertration of chloramphenicol in liver is higher than in the other, the depletion rate in high concentration was faster than in low concentration.

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Les stilbènes sont des composés phénoliques issus du métabolisme secondairevégétal, dont la distribution au sein du règne végétal est limitée aux espèces qui ont acquis aucours de l’évolution la capacité à synthétiser ces molécules. Leurs impacts et leurs activitésbiologiques tels que les effets neuroprotecteurs, anticancérigènes, antioxydants ont déjàconcerné plusieurs sujets d’étude. C’est dans ce contexte que l’objectif de notre travail a prisnaissance. Dans un premier temps, nous avons isolé et identifié ces molécules chez quelquesespèces de la famille des Cypéracées. Cette étude phytochimique a été réalisée en utilisant unensemble de stratégies analytiques et préparatives faisant appel à la CLHP analytique etpréparative et la CPC (Chromatographie de Partage Centrifuge) pour l’obtention desmolécules pures et à la LC-Masse et la RMN pour l’identification des composées isolés. Dansun second temps, nous avons étudié les activités biologiques in vitro de ces produits telles queles activités antioxydantes par trois méthodes (ORAC, DPPH et MCA) et l’effet de cesstilbènes sur la cytotoxicité neuronale induite par le peptide β-amyloïde avec des cellulesPC12. Nous avons isolé une nouvelle molécule, le carexinol A, pour la première fois, qui amontré une forte activité anti-amyloïde. La dernière partie de cette thèse fait état de l’analyseet du dosage des stilbènes dans des vins tunisiens dont le vin Sidi Zahia qui a donné lesmeilleurs résultats. / Stilbenes are phenolic compounds of plant secondary metabolism, whosedistribution within the plant kingdom is limited to species that have acquired during theevolution the ability to synthesize these molecules. Their impacts and their biologicalactivities such as neuroprotective, anticarcinogenic, antioxidant effects have already touchedseveral topics. It is in this context that the purpose of our work arose. First, we have isolatedand identified these molecules in some species of the sedge family. Phytochemical studieswere performed using a set of analytical and preparative strategies by means of analytical andpreparative HPLC and CPC (Centrifugal Partition Chromatography) for obtaining puremolecules and LC-Mass and NMR for identification of compound isolated. In a second step,we investigated the in vitro biological properties of these products such as antioxidantactivities by three methods (ORAC, DPPH and MCA) and their effect on neuronalcytotoxicity induced by β-amyloid peptide with PC12 cells. We isolated a new molecule, forthe first time, carexinol A, that showed strong anti-amyloid activity. The last part of this thesisrefers to the analysis and determination of stilbenes in Tunisian wines including Sidi Zahiawine that gave the best results.