Cycloartane triterpenes from Juncus effusus

A new triterpene, cycloart-23Z-enfe-3β,25-diol and other oxygenated cycloartanes have been isolated from Juncus effusus. The configurations at C-24 of the epimeric 24,25-epoxycycloartan-3β-ols, cycloart-25-ene-3β,24-diols and cycloartane-3β,24,25-triols have been attributed on the basis of chemical correlations. The 1H and 13C NMR chemical shifts of the 24R- and 24S-stereomers are also reported. © 1994

Structure elucidation and phytotoxicity of ecdysteroids from Chenopodium album.

The leaves of Chenopodium album were infused in H2O/MeOH. The extract treated with cold acetone gave heavy precipitation, which was removed by centrifugation. Solid material was fractionated into acidic and neutral fractions. The acidic material was subjected to different silica-gel column chromatographies, and then it was purified by reversed-phase HPLC to afford four known ecdysteroids and the new 3β,14α-dihydroxy-5β-pregn-7-ene-2,6,20-trione that were characterized by extensive spectroscopic investigation, especially by ID-and 2D-NMR. Their effects on germination and growth of Lactuca sativa L. have been studied. The results are reported as percentage differences of germination, root elongation and shoot elongation, from the control at concentrations ranging from 10-4 to 10-7 M. © 2005 Verlag Helvetica Chimica Acta AG, Zürich

Low molecular weight phenols from the bioactive aqueous fraction of Cestrum parqui.

The aqueous fraction of fresh leaves of Cestrum parqui and its organic fractions have been assayed for their phytotoxicity on Lactuca sativa, Lycopersicon esculentum, and Allium cepa. The tests showed that the bioactivity was retained in the organic fractions. Chromatographic processes led to isolation and characterization of the N-(p-carboxymethylphenyl)-p-hydroxybenzamide together with 17 low molecular weight phenols and 2 flavones. The phytotoxicity tests showed a good activity of these compounds on the target species. Comparison of some metabolites with commercial herbicides revealed a major activity of the natural compounds at lower concentrations