Bioensaios de atividade alelopática dos esteroides espinasterol, espinasterona e glicopiranosil espinasterol

Abstract

RESUMO -Três esteroides (espinasterol, espinasterona e glicopiranosil espinasterol) foram isolados do caule de Moutabea guianensis, planta de origem amazônica. Suas estruturas foram determinadas a partir das análises de RMN e por comparação com dados espectroscópicos da literatura. Foram avaliadas as atividades alelopáticas das três substâncias em duas plantas invasoras de pastagens comuns da região amazônica: Mimosa pudica (malícia) e Senna obtusifolia (mata-pasto). A substância glicopiranosil espinasterol foi mais ativa no ensaio de desenvolvimento da radícula, inibindo a espécie Senna obtusifolia em 75%; o espinasterol inibiu em 22% o desenvolvimento do hipocótilo de Senna obtusifolia; e no bioensaio de germinação de sementes as substâncias espinasterol e espinasterona proporcionaram 10% de inibição em Mimosa pudica. A partir desses resultados, observou-se que a diferença de substituintes observada na posição-3 dos esteroides é capaz de alterar a atividade alelopática. O grupo glicosil na posição-3 elevou a atividade alelopática de forma mais expressiva no bioensaio de desenvolvimento de radícula da espécie malícia, quando comparado aos esteroides hidroxilado e carbonilado. Este é o primeiro estudo químico e alelopático do gênero Moutabea. Palavras-chave: Moutabea guianensis, Polygalaceae, alelopatia, Senna obtusifolia, Mimosa pudica.ABSTRACT -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.

Phytotoxic Activity of dihydrochalcones Obtained by Bioreduction of Chalcones Promoted by the Endophytic Fungus Aspergillus lavus

“…[1][2][3] Entre as principais plantas invasoras de pastagens nessa região, merecem destaque M. pudica e S. obtusifolia, as quais são extremamente agressivas ao pasto. Assim, diversos trabalhos envolvendo alelopatia e efeitos fitotóxicos de substâncias produzidas por plantas 18,[34][35][36] e microrganismos (fungos endofíticos) 37-41 frente a essas duas espécies invasoras têm sido publicados.…”

Phytochemical screening and toxicity of Crambe abyssinica Hochst extracts on Solanum lycopersicum L., Euphorbia heterophylla L., Bidens pilosa L. and Glycine max (L.) Merril

“…Each solution was filtered and concentrated under reduced pressure, using the rotary evaporator Tecnal, model TE 211, obtaining then the respectively crude extracts. The extraction was performed during six days, according to Souza Filho et al (2005) and Ripardo Filho et al (2012).…”

“…Seeds of tomato, wild poinsettia and hairy beggartick were placed in petri dishes covered with two sheets of qualitative filter paper soaked with 3 mL of distilled water. After two days they were transferred to petri dishes containing each treatment (distilled water (negative control); commercial herbicide (positive control); hexane extract 1%; ethyl acetate extract 1% and methanolic extract 1%), using the methodology proposed by Souza Filho et al (2010) and Ripardo Filho (2012). For the cultivated species (soybean) paper rolls were used as substrate (BRASIL, 2009).…”

Phytotoxic activity of compounds from Moutabea guianensis aubl. on Amazonian invasive species

“…Moutabea guianensis is an Amazonian species that belongs to the family Polygalaceae, commonly known as cipó gogó de guariba [5]. Xanthones [6], coumarins [7], triterpenoids [8,9] steroids [10], flavonoids [11], pyrones [12,13] and xanthones [14,15] have been isolated from the species of the family Polygalaceae. In this study, from the roots of M. guianensis were isolated two compounds, the phenylpropanoid derivative methyl caffeate (1) and the coumarin scopoletin (2).…”