Síntese e estudo da atividade fungicida do avenaciolídeo e de novas bis-lactonas análogas

• Autor(a) principal: Barrros, Pauline Martins de
• Data de Publicação: 2008
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/2045
• topic: Fungicidas; Síntese de análogos; Avenaciolídeo; Bis-lactonas; Fungicides; Analogues synthesis; Avenaciolide; Bis-lactones; CNPQ::CIENCIAS EXATAS E DA TERRA::QUIMICA::QUIMICA ORGANICA

The synthetic route used in this present work has as starting material the carbohydrate D-glucose. Carbohydrates are very useful as synthetic precurssors, mainly due to the enantiomeric purity and the presence of many functional groups. From the D-glucose, several reactions were carried out, obtaining a total of 30 compounds, and 18 of them are new compounds. The final compounds of the various synthetic routes are (1R,5R,6R)-6-alkyl-4-methylidene-2,7- dioxabicyclo[3.3.0]octan-3-ones, and the alkyl groups are: propyl [XIIIa], butyl [XIIIb], 3-methylbutyl [XIIIc] and octyl [XIIId]. The bis-lactone [XIIId] is the natural product (-) venaciolide, which can be isolated from cultures of Aspergillus avenaceus, possessing antifungal activity. The avenaciolide and the synthetic analogues were subjected to biological tests, at concentrations of 1000 and 3000 ppm, for the evaluation of the antifungal activity against Colletotrichum gloeosporioides. All compounds were active. Avenaciolide was the most active compound, with percentages of inhibition of 48.5% at 1000 ppm, and 75.9% at 3000 ppm, in relation to tebuconazol, active component of the commercial fungicide Folicur®. The percentage of inhibition for the analogues [XIIIa], [XIIIb] and [XIIIc] at the concentration of 1000 ppm were 31.9%, 32.5% and 34.1%, respectively, and at 3000 ppm were 44.3%, 64.0% and 60.0%, respectively. These results indicate that a longer side chain increases the activity of the bis-lactones.