Artigos Científicos - FAQUI/ICEN
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Navegando Artigos Científicos - FAQUI/ICEN por Assunto "Aleloquímico"
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Artigo de Periódico Acesso aberto (Open Access) Aleloquímico produzido pela gramínea forrageira Brachiaria humidicola(2005-03) SOUZA FILHO, Antonio Pedro da Silva; PEREIRA, Angela Albertina Gaspar; BAYMA, Joaquim de CarvalhoThe traditional methods of weed control in cultivated pasture do not meet society's present and future needs of protecting natural resources and life quality. An alternative to this problem could be the use of secondary metabolites produced by plants. These products present few risks to the environment and meet society interests. Therefore, this research was carried out to isolate, identify and characterize the allelopathic activity of chemical compounds produced by the forage grass Brachiaria humidicola. The allelopathic effects of the extracts, fractions and compound were tested on seed germination and root elongation of the weeds Mimosa pudica, Senna obtusifolia and Senna occidentalis. Germination bioassays were developed under 25 ºC and a photoperiod of 12 hours. For root elongation, the bioassay conditions were 25 ºC and photoperiod of 24 hours. Hydromethanolic extract was used as a source for isolating and identifying p-coumaric acid. The allelopathic effects were positively related to p-coumaric acid concentration, weed species and the evaluated parameter. Comparatively, S. occidentalis and M. pudica showed the greatest sensitivity to the allelopathic effects. For S. obtusifolia no allelopathic effects promoted by p-coumaric acid on seed germination or on root elongation could be detected under the concentration of 1.0 and 8.0 mg L-1. Root elongation was more sensitive to p-coumaric acid allelophatic effects than seed germination.Artigo de Periódico Acesso aberto (Open Access) Atividade alelopática de chalcona sintética, de seus precursores e de cetonas e aldeídos relacionados(2007-12) BITENCOURT, Heriberto Rodrigues; SANTOS, Lourivaldo da Silva; SOUZA FILHO, Antonio Pedro da SilvaSeveral secondary metabolites produced by plants can be used as herbicides. These products are expected to offer fewer risks to the environment and to meet social demands. However, the availability of compounds is very limited, so synthesis is an alternative. The objective of this work was to evaluate the allelopathic activity of synthetic chalcone, 2,4'-dimethoxychalcone, its precursors, 4-methoxyacetophenone (A) and ortho-anisaldehyde (B), and some of their chemical alterations. The bioassays were developed under 25 ºC and photoperiod of 12 hours. The allelopathic effects of the compounds were tested on seed germination of Mimosa pudica and Senna obtusifolia weeds, under a concentration of 100, 200 and 300 mg L-1 of the compounds. The results indicated that precursor A (4-methoxyacetophenone) plays an important role in allelopathic activity of the chalcones. These results show that synthesis is a possible pathway, helping to overcome problems such as characterization and isolation of natural products with herbicidal activity against weed species.Artigo de Periódico Acesso aberto (Open Access) Substâncias químicas com atividades alelopáticas presentes nas folhas de Parkia pendula (Leguminosae)(2005-12) SOUZA FILHO, Antonio Pedro da Silva; FONSECA, Marcelo Lobato; ARRUDA, Mara Silvia PinheiroThe objective of this paper was to isolate, identify and characterize the allelopathic activity of chemical compounds produced by Parkia pendula. The allelopathic effects were evaluated on seed germination and radicle elongation of the weeds Mimosa pudica and Senna obtusifolia. The isolation process of the compounds involved the use of solvent in an increasing polarity order for extraction and the structural elucidation was carried out by Nuclear Magnetic Resonance, COPSY's and HETCOR's spectrum. The bioassays were carried out under controlled conditions of 25 ºC of temperature and 12-hour photoperiod for seed germination and 24-hour photoperiod for radicle elongation. The following allelochemicals were isolated and identified in P. pendula's leaves: 3,4,5-trimethoxybenzoic acid (S1), 3,4-dimethoxybenzoic acid (S2) and Blumenol A (S3). Comparatively, S1 and S2 showed greater allelopathic activity. The effects on radicle elongation were greater than those observed on seed germination. The isolated substances showed low inhibition potential on seed germination, especially on S. obtusifolia seeds. The allopathic inhibition effects were positively related to the concentration of the substances, although in some cases, these effects have not corresponded to the statistical differences.