Universiẗat, Diss., 2002--Bonn.

Três fungos endofíticos isolados de Viguiera robusta (Asteraceae) foram cultivados em três meios de cultivo distintos (Czapek, arroz e extrato de malte) e também em culturas binárias em extrato de malte. Para a extração dos cultivos em extrato de malte foi utilizada a resina diaion HP-20, que promove a adsorção dos metabólitos produzidos pelo fungo, aumentando o rendimento dos extratos. Os extratos e frações obtidos foram submetidos à análise química por meio de técnicas cromatográficas e RMN 1H e a ensaios diversos biológicos para a comparação de seus perfis. O estudo químico do extrato de Chaetomium globosum (VR-10), cultivado em arroz, levou a isolamento da substância S1 (chaetoglobosina E), que apresenta elevada atividade citotóxica e é uma ferramenta importante em biologia química. Também de C. globosum foi isolado a substância S2 (dimetil-tereftalato), o qual já foi identificado como metabólito de fungo endofítico e também de planta. De Pestalotiopsis guepini (VR-8), cultivado em Czapek, foi isolada a substância S3 (tirosol), relatado na literatura como molécula sinalizadora em Candida albicans. Do fungo Cladosporium sphaerospermum (VR-2), após cultivo em arroz, foram isoladas três substâncias: marcfortina A (S4), a marcfortina B (S5) e a marcfortina C (S6) e (S7), substâncias com pronunciada atividade antiparasitária. Foi desenvolvido um método via CLAE-DAD-MS/MS para identificação rápida de derivados de marcfortina, o qual possibilitiou a identificação da substância S7 (marcfortina D) no extrato bruto de C. sphaerospermum. A análise conformacional da marcfortina A (S4) foi realizada através de experimentos de NOE-diff e técnicas de modelagem molecular. Os resultados obtidos nos bioensaios após diferentes cultivos dos fungos endofíticos indicaram que estes são fontes promissoras de substâncias bioativas, constituindo ferramentas importantes na busca por novos compostos. / Three endophytic fungi isolated from Viguiera robusta (Asteraceae) were cultivated in three different culture media (Czapek, rice and malt extract) and also in mixed cultures in the malt extract medium. Diaion HP-20 resin was used for the malt extract cultures extraction increasing the yields of the extracts. Extracts and fractions have been submitted to chemical analyses by chromatographic techniques and 1H NMR, and also to several bioassays for the comparison of their chemical and biological profiles. Chemical study of the rice culture extract from Chaetomium globosum (VR-10) gave the citotoxic compound S1 (chaetoglobosin E), an important chemical biology tool. C. globosum also led to the isolation of compound S2 (dimethyl-terephthalate), previously isolated from an endophytic fungus and also from plants. Compound S3 (tyrosol) has been isolated from the Czapek culture extract of Pestalotiopsis guepini (VR-8). Tyrosol has been reported as a quorum sensing molecule in Candida albicans. Three compounds have been isolated from Cladosporium sphaerospermum (VR-2) rice cuture extract: marcfortine A (S4), marcfortine B (S5) and marcfortine C (S6). Marcfortines have been reported as potent antiparasitic compounds. A HPLC-DAD-MS/MS was developed for the rapid identification of marcfortine derivatives, which allowed the identification of compound S7 (marcfortine D) in the crude extract from C. sphaerospermum. The conformational analysis of marcfortine A (S4) was carried out by NOE-diff experiments and molecular modeling techniques. Bioassays results showed that the endophytic fungi should be considered as promising sources of novel and bioactive compounds.

Três fungos endofíticos isolados de Viguiera robusta (Asteraceae) foram cultivados em três meios de cultivo distintos (Czapek, arroz e extrato de malte) e também em culturas binárias em extrato de malte. Para a extração dos cultivos em extrato de malte foi utilizada a resina diaion HP-20, que promove a adsorção dos metabólitos produzidos pelo fungo, aumentando o rendimento dos extratos. Os extratos e frações obtidos foram submetidos à análise química por meio de técnicas cromatográficas e RMN 1H e a ensaios diversos biológicos para a comparação de seus perfis. O estudo químico do extrato de Chaetomium globosum (VR-10), cultivado em arroz, levou a isolamento da substância S1 (chaetoglobosina E), que apresenta elevada atividade citotóxica e é uma ferramenta importante em biologia química. Também de C. globosum foi isolado a substância S2 (dimetil-tereftalato), o qual já foi identificado como metabólito de fungo endofítico e também de planta. De Pestalotiopsis guepini (VR-8), cultivado em Czapek, foi isolada a substância S3 (tirosol), relatado na literatura como molécula sinalizadora em Candida albicans. Do fungo Cladosporium sphaerospermum (VR-2), após cultivo em arroz, foram isoladas três substâncias: marcfortina A (S4), a marcfortina B (S5) e a marcfortina C (S6) e (S7), substâncias com pronunciada atividade antiparasitária. Foi desenvolvido um método via CLAE-DAD-MS/MS para identificação rápida de derivados de marcfortina, o qual possibilitiou a identificação da substância S7 (marcfortina D) no extrato bruto de C. sphaerospermum. A análise conformacional da marcfortina A (S4) foi realizada através de experimentos de NOE-diff e técnicas de modelagem molecular. Os resultados obtidos nos bioensaios após diferentes cultivos dos fungos endofíticos indicaram que estes são fontes promissoras de substâncias bioativas, constituindo ferramentas importantes na busca por novos compostos. / Three endophytic fungi isolated from Viguiera robusta (Asteraceae) were cultivated in three different culture media (Czapek, rice and malt extract) and also in mixed cultures in the malt extract medium. Diaion HP-20 resin was used for the malt extract cultures extraction increasing the yields of the extracts. Extracts and fractions have been submitted to chemical analyses by chromatographic techniques and 1H NMR, and also to several bioassays for the comparison of their chemical and biological profiles. Chemical study of the rice culture extract from Chaetomium globosum (VR-10) gave the citotoxic compound S1 (chaetoglobosin E), an important chemical biology tool. C. globosum also led to the isolation of compound S2 (dimethyl-terephthalate), previously isolated from an endophytic fungus and also from plants. Compound S3 (tyrosol) has been isolated from the Czapek culture extract of Pestalotiopsis guepini (VR-8). Tyrosol has been reported as a quorum sensing molecule in Candida albicans. Three compounds have been isolated from Cladosporium sphaerospermum (VR-2) rice cuture extract: marcfortine A (S4), marcfortine B (S5) and marcfortine C (S6). Marcfortines have been reported as potent antiparasitic compounds. A HPLC-DAD-MS/MS was developed for the rapid identification of marcfortine derivatives, which allowed the identification of compound S7 (marcfortine D) in the crude extract from C. sphaerospermum. The conformational analysis of marcfortine A (S4) was carried out by NOE-diff experiments and molecular modeling techniques. Bioassays results showed that the endophytic fungi should be considered as promising sources of novel and bioactive compounds.

Ce travail de thèse a été conduit dans le but d’élaborer des papiers résistants à l’eau liquide et ayant des propriétés antifongiques, ce par utilisation de composés biosourcés. Deux approches ont été proposées : soit une modification en surface par enduction, soit une modification des fibres de cellulose. Dans le cas de la modification en surface, deux formulations d’enductions ont été étudiées. La première, composée de chitosane et de carbonate de calcium précipité (PCC) modifié, a été utilisée pour limiter le développement de moisissures et améliorer la résistance des papiers à l’eau. La formulation incorporant 20 % de PCC modifié a montré un retard de croissance significatif de la souche fongique sélectionnée en tant que souche cible. La seconde formulation, destinée à améliorer la résistance à l’eau des papiers, par enduction d'un latex prévulcanisé d’hévéa, a montré de très bons résultats, conduisant à une réduction de près de 95 % de l’absorption d’eau liquide. Toutefois, une perte d’opacité des papiers a été observée après pénétration de l’eau dans le matériau. Par conséquent, une seconde approche a été proposée, basée sur la modification physico-chimique des fibres de cellulose. Un procédé d’hybridation a été utilisé, permettant l’adsorption d’acide stéarique sur le PCC synthétisé in situ à la surface des fibres de cellulose. Un compromis entre la rétention des charges, la résistance à l’eau et les propriétés mécaniques a pu être proposé. Après détermination des conditions optimales de mise à l’échelle industrielle du procédé d’hybridation, un essai industriel a pu être réalisé et a conduit à des résultats prometteurs. / The present work investigates the creation of water-resistant and antifungal papers by using biobased compounds. Two approaches were developed: A surface modification by coating or a cellulose fibre modification. For the coating approach, two formulations were studied. The first one, consisting in chitosan and modified precipitated calcium carbonate (PCC) was mainly used to limit the development of molds while improving paper water resistance. The formulation incorporating 20 % of modified PCC showed a significant increase of the lag phase of the target fungal strain. The second coating formulation, especially designed to improve papers water resistance by a coating layer of prevulcanized natural rubber latex, showed very positive results, leading to 95 % reduction of liquid water absorption but with a negative impact on the material opacity after water penetration. As a consequence, physico-chemical modification of cellulose fibre was investigated in a second approach. An hybridization process was used, leading to stearic acid adsorption on in situ PCC synthesized at the surface of cellulosic fibres. A compromise between fillers retention, water resistance and mechanical properties was found. After determination of optimal conditions carried out to an industrial scale up, an industrial pilot was performed and gave promising results.