Síntese e atividade biológica de pironas e piridinonas derivadas do ácido desidroacético

• Autor(a) principal: Valente, Vânia Maria Moreira
• Data de Publicação: 2010
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/209
• topic: Pironas; Piridinonas; Ácido desidroacético; Fitotóxico; Pyrones; Pyridinones; Dehydroacetic acid; Phytotoxic; CNPQ::CIENCIAS EXATAS E DA TERRA::QUIMICA::QUIMICA ORGANICA

A large number of compounds containing the pyran-2-one or pyridine- 2-one ring have antibacterial, antifungal, antimalarial, cardiotonic, analgesic, anti-inflammatory, cytotoxic, neurotoxic, insecticide, anti-HIV, anti-oxidant and phytotoxic activity. The present work aimed at synthes of enamino pyranones containing the pyran-2-one ring and bis(pyridyl)methanes presenting the pyridin-2-one ring and, later, evaluating its phytotoxic activities. The antibacterial potential of bis(pyridyl)methanes was also evaluated. Dehydroacetic acid was used as starting material for the synthesis of these compounds. The synthesis of the sixteen enaminopyranones was carried out in a single stage, by the reaction of dehydroacetic acid with different amines (alkylamines, arylamines and amino methyl esters), withyields ranging from 49% to 97%. The syntheses of the thirty-three bis(pyridyl)methanes were carried out through a three-step synthetic route, in which the total yields ranged from 20% to 95%. The enaminopyranones and bis(pyridyl)methanes were evaluated as for their phytotoxic potential on the germination and root growth of Sorghum bicolor L. (sorghum) and Cucumis sativus L. (cucumber), and on the biomass production in sorghum, cucumber, Ipomoea grandifolia, Brachiaria decumbens, Amaranthus hibridus and Eleucine indica. Among the enaminopyranones, the most phytotoxic substance was (S,E)-3-(1-(sec-butylamine)ethylidene)-6-methyl- 3H-pyran-2,4-dione, which inhibited, in average, 83% of the production of biomass in I. grandifolia and 65% in B. decumbens, at the concentration of 5.0 x 10-4 mol L-1. B. decumbens (monocot) was the species with the least susceptibility to the enaminopyranones evaluated. Among the bis(pyridyl)methanes, the compound with the highest phytotoxic potential was 3,3'-((2- nitrophenyl)methylene) bis(4-hydroxy-6-methylpyridine-2(1H)-one), whose lowest inhibition value was 31.6% on the root system of sorghum and the highest value was 80.3% on the root system of brachiaria. Similarly to enaminopiranonas, it was observed lower susceptibility of monocots to bis(pyridyl)methanes. Although biomass production has been reduced, such reduction was less intense in the B. decumbens specie. The bis(pyridyl)methanes were also evaluated as for their antibacterial potential against Escherichia coli, Bacillus cereus and Staphylococcus aureus. However, no compound inbibited the growth of these bacteria. Several bis(pyridyl)methanes inhibited the urease activity. The presence of a nonreplaced aromatic ring, phenyl or furyl, ensured higher activity. It was observed that some compounds led to the growth of B. decumbens and inhibited urease activity. Such compounds can be considered candidates to be used as additives to urea-based fertilizers for pasture formation, since it can increase biomass production and, at the same time, decrease nitrogen losses caused by urease activity.