RESUMO
A short and efficient approach to a range of new chiral and achiral functionalized (E)-enaminopyran-2,4-diones starting with commercially available dehydroacetic acid is described. The phytotoxic properties of these (E)-enaminopyran-2,4-diones were evaluated by their ability to interfere with the growth of Sorghum bicolor and Cucumis sativus seedlings. A different sensitivity of the two crops was evident with the (E)-enaminopyran-2,4-diones. The most active compounds were also tested against two weeds, Ipomoea grandifolia and Brachiaria decumbens. To the best of our knowledge, this is the first report describing enaminopyran-2,4-diones as potential plant growth regulators.
Assuntos
Herbicidas/síntese química , Herbicidas/farmacologia , Reguladores de Crescimento de Plantas/síntese química , Piranos/síntese química , Brachiaria/efeitos dos fármacos , Cucumis sativus/efeitos dos fármacos , Cucumis sativus/crescimento & desenvolvimento , Ipomoea/efeitos dos fármacos , Reguladores de Crescimento de Plantas/farmacologia , Piranos/química , Piranos/farmacologia , Pironas/síntese química , Pironas/química , Pironas/farmacologia , Plântula/efeitos dos fármacos , Plântula/crescimento & desenvolvimento , Sorghum/efeitos dos fármacos , Sorghum/crescimento & desenvolvimento , Relação Estrutura-AtividadeRESUMO
Besides being vital tools in taxonomic evaluation, the anatomy of plant secretory structures and the chemical composition of their secretions may contribute to a more thorough understanding of the roles and functions of these secretory structures. Here we used standard techniques for plant anatomy and histochemistry to examine secretory structures on leaves at different stages of development of Prockia crucis, to evaluate the origin and development of the structures, and to identify the disaccharides and monosaccharides in the exudates. Fructose, glucose, and sucrose constituted up to 49.6% of the entire secretion. The glands were confirmed to be extrafloral nectaries (EFNs); this is the first report of their presence in the genus Prockia. These EFNs are globular, sessile glands, with a central concavity occurring on the basal and marginal regions of the leaf. The epidermis surrounding the concavity is secretory, forming a single-layered palisade that strongly reacts with periodic acid-Schiff's reagent (PAS) and xylidine Ponceau, indicators of total polysaccharides and total proteins, respectively, in the exudate. On the basis of the similarity of these glands to the salicoid teeth in Populus and Salix, we suggest that these three taxa are phylogenetically close.