Navegando por Assunto "Senna obtusifolia"

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Acesso aberto (Open Access)
Atividade alelopática de substâncias químicas isoladas da Acacia mangium e suas variações em função do PH
(2010) LUZ, Sylmara de Melo; SOUZA FILHO, Antonio Pedro da Silva; GUILHON, Giselle Maria Skelding Pinheiro; VILHENA, Karyme do Socorro de Souza
The aim of this study was to isolate, identify and characterize the allelopathic activity of the substances produced by Acacia mangium and to determine the variations of this activity according to the pH variation of the solution. The allelopathic activity was evaluated in germination bioassays (at 25 oC and under 12-12 h light-dark cycle) and radicle and hypocotyl development (at 25 oC and under 24-24 h light-dark cycle) of the weed species malicia (Mimosa pudica) and mata-pasto (Senna obtusifolia). The influence of the pH (3.0 and 9.0) of the solution in the allelopathic activity of the substances on seed germination of the same species was evaluated. The triterpenoids Lupenone (3 oxolup-20(29)-ene) and Lupeol (3β-hydroxylup-20(29)-ene), obtained from fallen leaves of the donor plant, separately and in pair, showed low allelopathic effects on seed germination and hypocotyl growth, especially on the former, with effects showing values lower than 2%. The effects on radicle growth were higher than the other two, reaching values above 40%, especially inhibition promoted by the substance Lupenone. Separately, each substance showed higher effects than those observed when tested in pair, indicating the existence of antagonism. The pH of the solution influenced the allelopathic activity of the substances; for Lupenone, the effects were more intense at acidic pH, while for Lupeol, best results were observed under alkaline conditions, showing that this is an important factor to be considered in field works.
Acesso aberto (Open Access)
Bioensaios de atividade alelopática dos esteroides espinasterol, espinasterona e glicopiranosil espinasterol
(2012-12) RIPARDO FILHO, Haroldo da Silva; PACHECO, Luidi Cardoso; SOUZA FILHO, Antonio Pedro da Silva; GUILHON, Giselle Maria Skelding Pinheiro; ARRUDA, Mara Silvia Pinheiro; SANTOS, Lourivaldo da Silva
Three steroids (spinasterol, spinasterone, and spinasterol glucopyranosyl) were isolated from the stem of the Amazonian plant Moutabea guianensis. Their structures were determined on the basis of NMR analysis and by comparison with spectroscopic data found in the literature. The allelopathic activities of the three substances were evaluated against two common weeds of the Amazon region, Mimosa pudica ('malicia') and Senna obtusifolia ('mata-pasto'). The substance spinasterol glucopyranosyl was the most active in the radicle growth bioassay, inhibiting Senna obtusifolia in 75%; spinasterol inhibited the development of hypocotyl of Senna obtusifolia in 22%, and spinasterone and spinasterol inhibited 10% of the seed germination of the species Mimosa pudica. These results showed that the difference of substitutes at the C-3 position of the steroids can influence allelopathic activity: the glicosyl group at the C-3 position enhanced the inhibition of hypocotyl growth of the species Mimosa pudica, compared to the hydroxilated and carbonylated steroid. This is the first chemical and allelopathic study with Moutabea guianensis.
Acesso aberto (Open Access)
Potencial herbicida da biomassa e de substâncias químicas produzidas pelo fungo endofítico Pestalotiopsis guepinii
(2008) SANTOS, Lourivaldo da Silva; OLIVEIRA, Marilene Nunes; GUILHON, Giselle Maria Skelding Pinheiro; SANTOS, Alberdan Silva; FERREIRA, Isabel Cristina Serrão; LOPES JÚNIOR, Manoel Leão; ARRUDA, Mara Silvia Pinheiro; SILVA, Milton Nascimento da; SOUZA FILHO, Antonio Pedro da Silva; RODRIGUES FILHO, Edson; OLIVEIRA, Maria da Conceição Ferreira de
Many of the chemical compounds found in nature that are produced by plants or microorganisms can offer new and efficient ways of controlling pests in agriculture and agricultural practice, with the help of fungi. The objective of this work is to characterize the inhibitory potential for seed germination and the plantlet development of two weed species using extracts and compounds obtained from biomass produced by Pestalotiopsis guepinii, an endophytic fungus of the species Virola michelii. The bioassays were developed under controlled conditions at 25 ºC and 12-hour photoperiod for germination, and at 25 ºC and 12-hour photoperiod for root and hypocotyl development. The crude extracts were analyzed at a concentration of 1.0% (m/v). The results showed that the more polar extracts (MeOH-1 and MeOH-2) have the highest inhibitory potential, although the hexane and ethyl acetate extract effects were important, especially for seed germination. Comparatively, weed seed germination was more sensitive to the effects than plantlet development. Mimosa pudica was more affected by the inhibitory effects of the extracts. However, for seed germination of Senna obtusifolia, the extract MeOH-1 showed 100% inhibition. The compounds ergosterol and ergosterol peroxide showed an inhibitory potential always below 35%, not showing the inhibitory potential of the hexane extract from which they were isolated. When these compounds were tested together, little increase was observed in the inhibitory activity.
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 Pinheiro
The 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.