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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

Synthèse d'analogues de mycosporines par catalyse à l'or et évaluation de leurs activités photoprotectrices

Nguyen, Khanh Hung 15 November 2013 (has links)
Le nombre de cancers et notamment de cancers photoinduits étant en augmentation, il est indispensable d’identifier de nouvelles molécules protectrices de type filtres UV, réparatrices vis-à-vis des altérations de l’ADN mais également favorisant la réponse pigmentaire. Les lichens sont des organismes originaux qui possèdent des qualités de résistance remarquables aux rayonnements solaires dues notamment à la production de métabolites photoprotecteurs tels que les mycosporines. A partir de ce motif structural original, nous avons synthétisé divers analogues par catalyse à l’or en utilisant un outil de la chimie théorique (TD-DFT) pour orienter les synthèses. Les premières évaluations de leurs propriétés physico-chimiques des molécules ont montré des activités prometteuses. / For several years, melanoma is the cancer with 84,000 new cases per year in Europe, including over 7000 cases in France, in 2010. One of the major causes of this cancer is the excessive exposure to UV radiations and it has been suggested that UV-A may be the primary cause of sunlight-induced melanoma. Hence, sunscreens with a good absorption in the UV-A spectral range need to be developed with a good efficacy and photostability. Lichens are original sources for the development of new UV filters because they possess ability to absorb UV due to the presence of metabolites such as mycosporines or MAAs (mycosporines like aminoacid). Based on the general structure of mycosporines, we have synthesized various analogues of mycosporines using a gold-catalyzed strategy. To orientate the synthesis, we used the method of the quantum chemistry: TD-DFT (Time-dependent density functional theory). These products were analyzed for their UV profiles and some of them showed good absorbing properties in UVA range. The cytotoxicity assay showed no toxicity of all products evaluated.

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