Federal do Acre, 69915-900 Rio Branco-AC, BrasilRecebido em 13/8/12; aceito em 4/2/13; publicado na web em 24/5/13 A phytochemical investigation of Maclura tinctoria fruits yielded five flavonoids, including one prenylated flavonol (licoflavonol) and four prenylated isoflavones (wighteone, derrone, alpinum isoflavone, and 6-(2,2-dimethyl-2H-chromen-6-yl)-2-(1-hydroxy-1-methylethyl)-2,3-dihydro-5H-furo[3,2-g]chromen-5-one). The structures of the isolates were established by analyzing their spectroscopic data. Compound 6-(2,2-dimethyl-2H-chromen-6-yl)-2-(1-hydroxy-1-methylethyl)-2,3-dihydro-5H-furo[3,2-g]chromen-5-one is new and the other isolates are described for the first time in this species.

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Studies of the phytotoxic effects between plants can be a crucial tool in the discovery of innovative compounds with herbicide potential. In this sense, we can highlight ruzigrass (Urochloa ruziziensis), which is traditionally used in the crop rotation system in order to reduce weed emergence. The aim of this work was to characterize the secondary metabolites of ruzigrass and to evaluate its phytotoxic effects. In total, eight compounds were isolated: friedelin, oleanolic acid, α‐amyrin, 1‐dehydrodiosgenone, sitosterol and stigmasterol glycosides, tricin and p‐coumaric acid. Phytotoxic effects of the crude methanolic extract and fractions of ruzigrass were assessed using germination rate, initial seedling growth, and biomass of Bidens pilosa, Euphorbia heterophylla and Ipomoea grandifolia. Chemometric analysis discriminated the weed species into three groups, and B. pilosa was the most affected by fractions of ruzigrass. The phytotoxic activities of 1‐dehydrodiosgenone, tricin, and p‐coumaric acid are also reported, and p‐coumaric acid and 1‐dehydrodiosgenone were active against B. pilosa.

The exogenous application of plant hormones and their analogues has been exploited to improve crop performance in the field. Protodioscin is a saponin whose steroidal moiety has some similarities to plant steroidal hormones, brassinosteroids. To test the possibility that protodioscin acts as an agonist or antagonist of brassinosteroids or other plant growth regulators, we compared responses of the weed species Bidens pilosa L. to treatment with protodioscin, brassinosteroids, auxins (IAA) and abscisic acid (ABA). Seeds were germinated and grown in agar containing protodioscin, dioscin, brassinolides, IAA and ABA. Root apex respiratory activity was measured with an oxygen electrode. Malondialdehyde (MDA) and antioxidant enzymes activities were assessed. Protodioscin at 48–240 μm inhibited growth of B. pilosa seedlings. The steroidal hormone 24‐epibrassinolide (0.1–5 μm) also inhibited growth of primary roots, but brassicasterol was inactive. IAA at higher concentrations (0.5–10.0 μm) strongly inhibited primary root length and fresh weight of stems. ABA inhibited all parameters of seedling growth and also seed germination. Respiratory activity of primary roots (KCN‐sensitive and KCN‐insensitive) was activated by protodioscin. IAA and ABA reduced KCN‐insensitive respiration. The content of MDA in primary roots increased only after protodioscin treatment. All assayed compounds increased APx and POD activity, with 24‐epibrassinolide being most active. The activity of CAT was stimulated by protodioscin and 24‐epibrassinolide. The results revealed that protodioscin was toxic to B. pilosa through a mechanism not related to plant growth regulator signalling. Protodioscin caused a disturbance in mitochondrial respiratory activity, which could be related to overproduction of ROS and consequent cell membrane damage.

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A phytochemical study of the ethyl acetate fractions from the partition of seeds and roots methanol extracts of Cenchrus echinatus L. led to the isolation of three resveratrol-derived stilbenoids: pallidol (1), carasiphenol C (2) and nepalensinol B (3). The results of a topic anti-inflammatory evaluation, DPPH assay and antiproliferative activity against adenocarcinoma cells (Caco 2) are described.

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Este artigo teve como objetivo analisar a usabilidade e as possibilidades pedagógicas de um jogo digital envolvendo o conteúdo de funções orgânicas no ensino da química orgânica através do uso de dispositivos móveis. Do ponto de vista metodológico, a pesquisa utiliza uma abordagem do tipo mista, tratando-se de um estudo de caso com delineamento sequencial exploratório, sendo realizada em quatro etapas. Participaram desta pesquisa estudantes do curso de licenciatura em Química da Universidade Federal do Acre que, após as intervenções didáticas, responderam quatro questionários avaliativos acerca das atividades realizadas. Os resultados da pesquisa indicam que, dependendo do modo de utilização, o aplicativo pode ser um recurso complementar no processo de ensino e aprendizagem da química orgânica, ao mesmo tempo que pode promover um ambiente engajador, competitivo e estimulante entre os estudantes, que se mostraram receptivos à utilização de jogos digitais.