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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Studies on the genetic and biochemical properties of a PUVA hyper-resistant mutant of Escherichia coli

Holland, Julie January 1990 (has links)
No description available.
2

Atom-economical chemoselective synthesis of furocoumarins via cascade palladium catalyzed oxidative aloxylation of 4-oxohydrocoumarins and alkenes

Tan, X., Zhao, H., Pan, Y., Wu, Na, Wang, H., Chen, Z. 02 June 2020 (has links)
No / A novel and efficient procedure for the synthesis of furo[3,2-c] coumarins from readily available 4-oxohydrocoumarins and alkenes in the presence of a catalytic amount of Pd(CF3COO)2 has been developed. Atom-economical characteristics and mild conditions of this method are in accord with the concept of modern green chemistry.
3

Estudo termoanalítico de furanocumarinas de Brosimum gaudichaudii Trécul / Thermoanalytical study of furocoumarins of Brosimum gaudichaudii Trécul

Rocha, Thaíza Carvalho da 28 May 2012 (has links)
Submitted by Jaqueline Silva (jtas29@gmail.com) on 2014-10-06T18:08:43Z No. of bitstreams: 2 Dissertação - Thaíza Carvalho da Rocha - 2012.pdf: 1513291 bytes, checksum: 5cdef676b716525fc5590bddb862c72f (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Approved for entry into archive by Jaqueline Silva (jtas29@gmail.com) on 2014-10-06T19:16:52Z (GMT) No. of bitstreams: 2 Dissertação - Thaíza Carvalho da Rocha - 2012.pdf: 1513291 bytes, checksum: 5cdef676b716525fc5590bddb862c72f (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Made available in DSpace on 2014-10-06T19:16:52Z (GMT). No. of bitstreams: 2 Dissertação - Thaíza Carvalho da Rocha - 2012.pdf: 1513291 bytes, checksum: 5cdef676b716525fc5590bddb862c72f (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2012-05-28 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Thermal analysis techniques have been very useful to study the pre-formulations since it consists in techniques that can provide quick and reliable results. This study evaluated the thermoanalytical profiles of psoralen and bergapten, compounds used in the treatment of vitiligo, and their interactions with excipients. We also evaluated the thermal profile of the plant extract Brosimum gaudichaudii Trécul (Moraceae) and a medicine containing the same extract. The results showed that psoralen and bergapten are substances with decomposition and have only one melting step at 162 ° C and 190 respectively. The compounds psoralen and bergapten interact with each other, but the results by XRD clearly show that the crystal structures of the compounds are not affected by these interactions. Furthermore, the results of thermal analysis showed that there was no interaction with the excipients of these compounds under study. All results were confirmed by FT-IR, used as a complementary technique. The plant extract showed an endothermic event which can be attributed to the fusion of these assets. The DSC curve profile of the drug trade allowed the detection of lactose in their composition, whose presence is not included in the package leaflet. / As técnicas de análise térmica tem se mostrado muito úteis no estudo de pré-formulações visto que consiste em técnicas que apresentam resultados rápidos e seguros. Neste trabalho foram avaliados os perfis termoanalíticos do psoraleno e bergapteno, compostos utilizados no tratamento de vitiligo, e suas interações com excipientes. Avaliou-se também o perfil térmico do extrato da planta Brosimum gaudichaudii Trécul (Moraceae) e de um medicamento contendo o mesmo extrato. Os resultados mostraram que psoraleno e bergapteno são substâncias que possuem decomposição em apenas uma etapa e apresentam fusão em 162 e 190 °C, respectivamente. Os compostos psoraleno e bergapteno interagem entre si, mas os resultados através de DRX deixam claro que as estruturas cristalinas dos compostos não são afetadas por essas interações. Além disso, os resultados obtidos com a análise térmica evidenciam que não ocorreu nenhuma interação destes compostos com os excipientes em estudo. Todos os resultados foram confirmados por FT-IR, utilizada como técnica complementar. O extrato da planta mostrou um evento endotérmico que pode ser atribuído à fusão dos ativos presentes. O perfil da curva DSC do medicamento comercial possibilitou a detecção da lactose em sua composição, cuja presença não consta na bula do medicamento.
4

Grapefruit-drug interaction: isolation, synthesis, and biological activities of furocoumarins and their variation due to pre- and post-harvest factors.

Girennavar, Basavaraj 15 May 2009 (has links)
The health maintaining properties of citrus consumption are attributed to the wide assortment of bioactive compounds. Consumption of grapefruit along with certain medications, however, is posing a risk of drug toxicity and side reactions. The first study involved isolation of bioactive furocoumarins with a combination of chromatographic techniques and synthesis. Five furocoumarins namely, dihydroxybergamottin, paradisin A, bergamottin, bergaptol and geranylcoumarin were isolated from grapefruit and series of furocoumarin monomers and paradisin A were synthesized. The second study involved influence of pre- and post-harvest factors on the levels of furocoumarins in grapefruit juice. Considerable differences were observed in the levels of these compounds in different grapefruit cultivars. Ray Red showed the lowest levels of all three furocoumarins and Duncan contains the highest amount of DHB and bergamottin, where as the highest levels of paradisin A was observed in Star Ruby. The highest levels of DHB and bergamottin were found in Flame cultivar grown in California. The changes in the levels of these furocoumarins during the season in Rio Red and Marsh White grapefruit cultivars were evaluated. The third study investigated biological activities of grapefruit juices and furocoumarins. Grapefruit and Pummelo juices were found to be potent inhibitors of cytochrome CYP3A4 and CYP2C9 isoenzymes at 5% concentration while CYP2D6 was less affected. Among the five furocoumarins tested, the inhibitory potency was in the order of paradisin A>dihydroxybergamottin>bergamottin>bergaptol>geranylcoumarin at 0.1 µM to 0.1 mM concentrations. A fourth study investigated the effect of furocoumarins on bacterial auto-inducer signaling, and found that furocoumarins are potent inhibitors of AI-1 and AI-2 activities at 0.01% concentration. In a fifth study, involving synthesized furocoumarin monomers and dimer on anti-proliferative activities on normal and cancer cell lines, furocoumarins found to be non-toxic to normal cells. However, bergamottin showed a significant anti-proliferative activity in HT-29 and MCF-7 cell lines. This dissertation indicates that furocoumarins are bioactive compounds from grapefruit juice with potent inhibitory property of major drug metabolizing cytochrome P450 isoenzymes. Furocoumarins show a considerable variation between varieties, location and season. These results corroborate the involvement of furocoumarins in grapefruit drug interaction.
5

Isolamento, caracterização e avaliação da atividade fotossensibilizadora de cumarinas e furanocumarinas extraídas de espécies de Citrus / Isolation, characterization and evaluation of photosensitizer activity of coumarins and furocoumarins extracted from Citrus species

Fracarolli, Letícia 23 September 2015 (has links)
O crescente aumento da tolerância aos fungicidas atualmente utilizados é um dos principais problemas tanto na área clínica quanto na agrícola e tem estimulado o desenvolvimento de estratégias alternativas para o controle de fungos patogênicos, tais como o tratamento fotodinâmico antimicrobiano (TFA), que pode utilizar fotossensibilizadores (FS) de origem natural ou sintética. Alguns FS, como as cumarinas e furanocumarinas, são produzidos por espécies de Citrus como limão Tahiti (Citrus latifolia) e toranjas (Citrus paradisi). O presente estudo investigou o TFA in vitro de conídios do fungo fitopatogênico Colletotrichum acutatum com: (1) o corante fenotiazínico azul de metileno (MB), (2) uma furanocumarina comercial, 8-metoxipsoraleno (8-MOP), (3) uma cumarina comercial, (2H-chromen-2-one), (4) a cumarina 5,7-dimetoxicumarina extraída no presente trabalho a partir de óleo da casca do limão Tahiti, (5) a cumarina 7-hidroxicumarina extraída no presente trabalho a partir de óleo essencial de toranja rubi, (6) duas frações extraídas por De Menezes e colaboradores (2014a) a partir de um resíduo da indústria citrícola, uma delas constituída pela furanocumarina isopimpinelina e outra constituída por uma mistura das cumarinas 7-metoxicumarina e 5,7-dimetoxicumarina (3:1), (7) cinco extratos brutos obtidos a partir de óleos da casca e essencial de limão Tahiti e óleos essenciais de toranjas rubi e branca. Com exceção do extrato bruto obtido do óleo essencial de toranja branca, todos os demais extratos apresentaram cumarinas e/ou furanocumarinas em sua composição. As suspensões de conídios foram tratadas com os diferentes compostos (50 ?M para os compostos comerciais e as frações puras e 12,5 mg L-1 para os extratos e a mistura) e expostas à radiação solar por 1 h. O MB foi exposto à radiação solar por 30 min, 1 e 2 h. Determinou-se o efeito do tratamento fotodinâmico em folhas de mudas de laranja Valencia (Citrus sinensis) com (1) 8-MOP, (2) mistura de cumarinas, (3) 5,7-dimetoxicumarina e (4) o extrato bruto de limão Tahiti. Adicionalmente, experimentos para avaliar a estabilidade do 8-MOP exposto à radiação solar por até 12 h foram realizados. Nesses experimentos, soluções de 8-MOP (50 ?M) foram expostas à radiação solar e alíquotas foram retiradas após os diferentes tempos de exposição. Após as exposições, estudos de espectroscopia de absorção no UV e emissão de fluorescência foram realizados, além da realização de experimentos para avaliar a eficácia do TFA com os FS previamente expostos à radiação solar por 6 e 12 h. Os TFA mais eficazes foram com o MB, 8-MOP (ambos 50 ?M), a mistura de cumarinas e um dos extratos brutos obtidos de limão Tahiti (ambos 12,5 mg L-1), que mataram 99,998%, 99,378%, 99,336% e 65,049% dos conídios, respectivamente, após 1 h de exposição à radiação solar. Nenhum dano nas folhas de laranja foi observado após o TFA com os compostos. Os espectros de absorção e emissão de fluorescência das soluções de 8-MOP expostas à radiação solar mostraram fotodegradação do composto após 12 h de exposição. Entretanto, as soluções de 8-MOP expostas por 6 e por 12 h ainda foram capazes de matar 99,978% e 95,591% dos conídios de C. acutatum, respectivamente / Increasing tolerance to currently used fungicides is a major problem both in clinical and agricultural areas and has stimulated the development of alternative strategies to control pathogenic fungi such as the antimicrobial photodynamic treatment (APDT), that can use natural or synthetic photosensitizers (PS). Some PS, such as coumarins and furocoumarins are produced by Citrus species such Tahiti acid lime (Citrus latifolia) and grapefruit (Citrus paradisi). This study investigated the in vitro APDT of conidia of the plant-pathogenic fungi C. acutatum with: (1) the phenothiazinium dye methylene blue (MB), (2) commercial furocoumarin, 8-methoxypsoralen (8-MOP), (3) commercial coumarin (2H-chromen-2-one), (4) coumarin 5,7-dimethoxycoumarin, extracted in this study from Tahiti lime peel oil, (5) coumarin 7-hidroxycoumarina, extracted in this study from ruby grapefruit essential oil, (6) two fractions extracted by De Menezes et al (2014a) from a Citrus industry residue, one of them constituted by the furocoumarin isopimpinellin, and the other constituted by the mixture of coumarins 7-methoxycoumarin and 5,7-dimethoxycoumarin (3:1), (7) five crude extracts obtained from Tahiti lime peel or essential oil and ruby and white grapefruit essential oil. Except the extract from the white grapefruit, all the others presented coumarins and/or furocoumarins in their composition. Conidial suspentions were treated with the different PS (50 ?M for commercial and pure compounds and 12.5 mg L-1 for the extracts and the mixture) and exposed to solar radiation for 1 h. The MB was exposed to solar radiation for 30 min, 1 and 2 h. The APDT effect on the leaves of Valencia orange trees (Citrus sinensis) with (1) 8-MOP, (2) the mixture of coumarins, (3) 5,7-dimethoxycoumarin, and (4) the most efective extract from Tahiti lime were determined. Additionally, experiments to assess the 8-MOP stability after exposure to solar radiation for 12 h were realized. 8-MOP solutions (50 ?M) were exposed under solar radiation and rates were removed after different times of exposition. After the expositions, absorption spectroscopic studies in UV and fluorescence emission were realized, as well as holding the realization of experiments of APDT efficacy evaluation after 6 and 12 h to exposure under solar radiation. The more effective treatments were with MB, 8-MOP (both 50 ?M), the coumarins mixture and one of the extracts from Tahiti lime (both 12.5 mg L-1), killing at least 99,998%, 99,378%, 99,336% and 65,049% of the conidia, respectively after 1 h under solar radiation. No damage to orange tree leaves was observed after APDT with any of the compounds. The absorption and fluorescence intensity spectra showed the 8-MOP photodegradation after 12 h of exposition, although the 8-MOP solutions exposed under solar radiation for 6 and 12 h still killed at least 99,978% and 95,591% of the C. acutatum conidia, respectively
6

Isolamento, caracterização e avaliação da atividade fotossensibilizadora de cumarinas e furanocumarinas extraídas de espécies de Citrus / Isolation, characterization and evaluation of photosensitizer activity of coumarins and furocoumarins extracted from Citrus species

Letícia Fracarolli 23 September 2015 (has links)
O crescente aumento da tolerância aos fungicidas atualmente utilizados é um dos principais problemas tanto na área clínica quanto na agrícola e tem estimulado o desenvolvimento de estratégias alternativas para o controle de fungos patogênicos, tais como o tratamento fotodinâmico antimicrobiano (TFA), que pode utilizar fotossensibilizadores (FS) de origem natural ou sintética. Alguns FS, como as cumarinas e furanocumarinas, são produzidos por espécies de Citrus como limão Tahiti (Citrus latifolia) e toranjas (Citrus paradisi). O presente estudo investigou o TFA in vitro de conídios do fungo fitopatogênico Colletotrichum acutatum com: (1) o corante fenotiazínico azul de metileno (MB), (2) uma furanocumarina comercial, 8-metoxipsoraleno (8-MOP), (3) uma cumarina comercial, (2H-chromen-2-one), (4) a cumarina 5,7-dimetoxicumarina extraída no presente trabalho a partir de óleo da casca do limão Tahiti, (5) a cumarina 7-hidroxicumarina extraída no presente trabalho a partir de óleo essencial de toranja rubi, (6) duas frações extraídas por De Menezes e colaboradores (2014a) a partir de um resíduo da indústria citrícola, uma delas constituída pela furanocumarina isopimpinelina e outra constituída por uma mistura das cumarinas 7-metoxicumarina e 5,7-dimetoxicumarina (3:1), (7) cinco extratos brutos obtidos a partir de óleos da casca e essencial de limão Tahiti e óleos essenciais de toranjas rubi e branca. Com exceção do extrato bruto obtido do óleo essencial de toranja branca, todos os demais extratos apresentaram cumarinas e/ou furanocumarinas em sua composição. As suspensões de conídios foram tratadas com os diferentes compostos (50 ?M para os compostos comerciais e as frações puras e 12,5 mg L-1 para os extratos e a mistura) e expostas à radiação solar por 1 h. O MB foi exposto à radiação solar por 30 min, 1 e 2 h. Determinou-se o efeito do tratamento fotodinâmico em folhas de mudas de laranja Valencia (Citrus sinensis) com (1) 8-MOP, (2) mistura de cumarinas, (3) 5,7-dimetoxicumarina e (4) o extrato bruto de limão Tahiti. Adicionalmente, experimentos para avaliar a estabilidade do 8-MOP exposto à radiação solar por até 12 h foram realizados. Nesses experimentos, soluções de 8-MOP (50 ?M) foram expostas à radiação solar e alíquotas foram retiradas após os diferentes tempos de exposição. Após as exposições, estudos de espectroscopia de absorção no UV e emissão de fluorescência foram realizados, além da realização de experimentos para avaliar a eficácia do TFA com os FS previamente expostos à radiação solar por 6 e 12 h. Os TFA mais eficazes foram com o MB, 8-MOP (ambos 50 ?M), a mistura de cumarinas e um dos extratos brutos obtidos de limão Tahiti (ambos 12,5 mg L-1), que mataram 99,998%, 99,378%, 99,336% e 65,049% dos conídios, respectivamente, após 1 h de exposição à radiação solar. Nenhum dano nas folhas de laranja foi observado após o TFA com os compostos. Os espectros de absorção e emissão de fluorescência das soluções de 8-MOP expostas à radiação solar mostraram fotodegradação do composto após 12 h de exposição. Entretanto, as soluções de 8-MOP expostas por 6 e por 12 h ainda foram capazes de matar 99,978% e 95,591% dos conídios de C. acutatum, respectivamente / Increasing tolerance to currently used fungicides is a major problem both in clinical and agricultural areas and has stimulated the development of alternative strategies to control pathogenic fungi such as the antimicrobial photodynamic treatment (APDT), that can use natural or synthetic photosensitizers (PS). Some PS, such as coumarins and furocoumarins are produced by Citrus species such Tahiti acid lime (Citrus latifolia) and grapefruit (Citrus paradisi). This study investigated the in vitro APDT of conidia of the plant-pathogenic fungi C. acutatum with: (1) the phenothiazinium dye methylene blue (MB), (2) commercial furocoumarin, 8-methoxypsoralen (8-MOP), (3) commercial coumarin (2H-chromen-2-one), (4) coumarin 5,7-dimethoxycoumarin, extracted in this study from Tahiti lime peel oil, (5) coumarin 7-hidroxycoumarina, extracted in this study from ruby grapefruit essential oil, (6) two fractions extracted by De Menezes et al (2014a) from a Citrus industry residue, one of them constituted by the furocoumarin isopimpinellin, and the other constituted by the mixture of coumarins 7-methoxycoumarin and 5,7-dimethoxycoumarin (3:1), (7) five crude extracts obtained from Tahiti lime peel or essential oil and ruby and white grapefruit essential oil. Except the extract from the white grapefruit, all the others presented coumarins and/or furocoumarins in their composition. Conidial suspentions were treated with the different PS (50 ?M for commercial and pure compounds and 12.5 mg L-1 for the extracts and the mixture) and exposed to solar radiation for 1 h. The MB was exposed to solar radiation for 30 min, 1 and 2 h. The APDT effect on the leaves of Valencia orange trees (Citrus sinensis) with (1) 8-MOP, (2) the mixture of coumarins, (3) 5,7-dimethoxycoumarin, and (4) the most efective extract from Tahiti lime were determined. Additionally, experiments to assess the 8-MOP stability after exposure to solar radiation for 12 h were realized. 8-MOP solutions (50 ?M) were exposed under solar radiation and rates were removed after different times of exposition. After the expositions, absorption spectroscopic studies in UV and fluorescence emission were realized, as well as holding the realization of experiments of APDT efficacy evaluation after 6 and 12 h to exposure under solar radiation. The more effective treatments were with MB, 8-MOP (both 50 ?M), the coumarins mixture and one of the extracts from Tahiti lime (both 12.5 mg L-1), killing at least 99,998%, 99,378%, 99,336% and 65,049% of the conidia, respectively after 1 h under solar radiation. No damage to orange tree leaves was observed after APDT with any of the compounds. The absorption and fluorescence intensity spectra showed the 8-MOP photodegradation after 12 h of exposition, although the 8-MOP solutions exposed under solar radiation for 6 and 12 h still killed at least 99,978% and 95,591% of the C. acutatum conidia, respectively
7

Modification de la synthèse des furocoumarines chez Ruta graveolens L. par une approche de génie métabolique / Functional exploration of the biosynthesis pathway of phenylpropanoids of Ruta graveolens by metabolic engineering

Doerper, Sébastien 12 November 2008 (has links)
La rue officinale (Ruta graveolens L) est une plante connue comme étant particulièrement riche en métabolites secondaires et produisant notamment des molécules d’intérêt pharmaceutique comme les furocoumarines. Nous avons tenté par une approche de génie métabolique d’augmenter la teneur en furocoumarines produites dans les plantes. La mise en place de telles approches nous a également permis de mieux comprendre les mécanismes de régulation de la voie de biosynthèse des phénylpropanoïdes. Pour atteindre ces objectifs nous avons transformé la rue avec différents gènes placés sous le contrôle d’un promoteur constitutif fort, le promoteur 35S du CaMV. Pour chaque série de transformants nous avons étudié la teneur en furocoumarines et analysé les variations de composés phénylpropanoïdes (rutine, umbelliférone, ferulate, scopolétine). Parallèlement à cette analyse métabolique, une corrélation a été réalisée avec le niveau d’expression des transgènes et de certains endogènes par l’utilisation d’approche de PCR quantitative. Les séries de plantes transgéniques surexprimant les gènes codants pour la Coumaroyl ester 3’-Hydroxylase de rue (CYP98A22) et d’A. thaliana (CYP98A3) présentent toutes les deux une augmentation significative d’une facteur 3 de la teneur en furocoumarines. Par contre si les premières sont caractérisées par une diminution de la production en rutine et en umbelliférone, les secondes présentent une augmentation importante de la teneur en Scopolétine et en umbelliférone. Ces résultats suggèrent la coexistence de deux C3’H chez R. graveolens ayant des fonctions différentes, l’une d’entre elles étant impliquée directement ou non dans la synthèse de scopolétine. Si la transformation génétique de rues avec des gènes de la famille CYP98A induit des modifications du métabolisme secondaire, la surexpression d’un gène spécifique à la voie de biosynthèse des furocoumarines (gène cyp71AJ1, codant pour la psoralène synthase d’A. majus) permet d’augmenter uniquement la teneur en furocoumarines (X4). L’ensemble de ces travaux a permis de montrer l’intérêt d’une approche de génie métabolique pour générer des plantes présentant un intérêt potentiel pour la production de molécules d’intérêts pharmaceutiques / Garden Rue (Ruta graveolens L.) is a plant known as being particularly rich in secondary metabolites and in particular producing molecules of pharmaceutical interest like furocoumarines. By the use of a metabolic engineering approach, we tried to increase the content of furocoumarines produced in these plants but also to better understand the regulation mechanisms of the phenylpropanoïd biosynthesis pathway. To achieve these goals we transformed Ruta plants with various genes placed under the control of a strong constitutive promoter, CaMV 35S promoter. The plants we obtained were analyzed for their ability to overproduce furocoumarines but also other phenylpropanoïds like ferulate, umbelliferone, scopoletine or rutin. Using Real Time PCR experiments, a correlation was carried out with the level of expression of each transgene and several endogenous genes. Plants overexpressing either the Ruta or the Arabidopsis Coumaroyl ester 3 '-Hydroxylase (CYP98A22 and CYP98A3 respectively) display both a significant increase (3 time level) of the furocoumarin. However if the S-98A22 plants are characterized by a reduction in the production of rutin and umbelliferone, S-98A3 transgenic plants display a significant increase scopoletine and umbelliferone content. These results suggest the coexistence of two C3'H having different functions in Ruta. One of them might be involved more specifically in the synthesis of scopoletine. If the transformation of Ruta with genes belonging to the CYP98A family generates an enlarged of the secondary metabolism, we also showed that the overexpression of a gene belonging to the furocoumarins biosynthesis pathway (CYP71AJ1, the psoralen synthase) allowed a specific stimulation. Indeed a 4 time increase of the content of furocouramins was noticed in these transgenic plant lines. This work made it possible to make evidence of the interest of a metabolic engineering approach to generate plants of interest for the production of pharmaceutical molecules
8

Contribution à l'étude des P450 impliqués dans la biosynthèse des furocoumarines / Study of P450 involved in furocoumarin biosynthesis

Larbat, Romain 30 May 2006 (has links)
Les furocoumarines sont des phytoalexines offrant un potentiel thérapeutique important. Les travaux présentés ici portent sur les cytochromes P450 participant à leur voie de biosynthèse. Une étude «structure-fonction» de la cinnamate-4-hydroxylase (C4H) a été réalisée pour identifier les déterminants de la faible sensibilité de la C4H de Ruta graveolens (CYP73A32) au psoralène. Deux régions protéiques semblent impliquées dans l’inactivation différentielle entre CYP73A32 et CYP73A1. L’une, entre les résidus 31 et 58, est responsable de l’affinité pour le psoralène. L’autre, entre les résidus 229 et 379, contrôle la vitesse d’inactivation. La caractérisation de nouveaux P450 de la biosynthèse des furocoumarines a été entreprise. D’une part, plusieurs ADNc partiels ont été clonés chez Ruta graveolens. D’autre part, CYP71AJ1 isolé chez Ammi majus, a été caractérisé comme étant une psoralène synthase. La spécificité de CYP71AJ1 pour la marmésine a été approchée par l’étude d’un modèle 3D. Mots clés : cytochrome P450, psoralène synthase, cinnamate-4-Hydroxylase, C4H, métabolite secondaire, Ruta graveolens, Ammi majus, inactivation autocatalytique, furocoumarines, psoralène, (+)-marmésine, Modélisation 3D, (+)-columbianetine / Furocoumarins are phytoalexins known as efficient therapeutic agents. The work reported here focuses on cytochromes P450 involved in their biosynthesis pathway. A “structure-function” study was realized to understand how C4H from Ruta graveolens (CYP73A32) can resist to psoralen mechanism-based inactivation. Two parts of the protein seems involved in the differential susceptibility of CYP73A32 and CYP73A1 to psoralen. The first, between amino acids 31 and 58, defines differential affinity to psoralen. The second between residues 229 and 379 controls inactivation kinetic. The second part of this work was devoted to cloning and identification of new P450 involved in furocoumarin biosynthesis. On the one hand, several partial cDNA were cloned from Ruta graveolens. On the other hand, CYP71AJ1, cloned from Ammi majus, was identified as a psoralen synthase. The specificity of CYP71AJ1 for marmesin was approached by the study of a 3D model.

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