- Iridoid glycosides from the stems of Pithecoctenium crucigerum (Bignoniaceae)
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Sixteen crude extracts from six Panamanian plants of the family Bignoniaceae were submitted to rapid TLC tests against DPPH and acetylcholinesterase. Pithecoctenium crucigerum (L.) A.H. Gentry, which showed interesting activity against DPPH, has been studied. The chemical investigation of the methanol extract from the stems afforded the iridoid glycoside theviridoside and three derivatives (6′-O-cyclopropanoyltheviridoside, 10-O-hydroxybenzoyltheviridoside and 10-O-vanilloyltheviridoside), along with five known phenylethanoid glycosides (verbascoside, isoverbascoside, forsythoside B, jionoside D and leucosceptoside B). These last compounds were all active against DPPH. The structures were determined by means of spectrometric and chemical methods, including 1D and 2D NMR experiments and MS analysis.
- Martin, Frederic,Hay, Anne-Emmanuelle,Corno, Laura,Gupta, Mahabir P.,Hostettmann, Kurt
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- BIOSYNTHESIS OF IRIDOID GLUCOSIDES IN HEBENSTRETIA DENTATA
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Deuterium-labelled samples of 8-epi-iridodial, 8-epi-iridotrial and their glucosides were fed to Hebenstretia dentata.The aglucones were better precursors than their glucosides of ipolamiide and lamiide, the iridoid glucosides of the plant.A feeding experiment with (13)C-labelled 10-hydroxy-geraniol showed that C-3 and C-11 are equivalent during biosynthesis of the iridoid glucosides and, thus, glucosidation must take place after formation of 8-epi-iridotrial.Isolation of the minor metabolites after feeding with 8-epi-deoxyloganic acid suggested that the route from this compound proceeds by oxidation at C-8 followed by esterification and that oxidation at C-5 is the final step. Key Word Index: Hebenstretia dentata; Scrophulariaceae; iridoid glucosides; ipolamiide; lamiide; biosynthesis; (2)H NMR.
- Damtoft, Soeren,Jensen, Soeren Rosendal,Nielsen, Bent Juhl,Thorsen, Jesper
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p. 3839 - 3844
(2007/10/02)
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- Identification of the Iridoid Glucoside Theveside in Lantana camara (Verbenaceae), and Determination of its Structure and Stereochemistry by Means of N.M.R.
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The iridoid glucoside theveside has been isolated from the leaves and stems of three taxa of Lantana camara (Verbenaceae), where it occurs as the sodium salt.Elucidation of the structure was primarily from 1H and 13C n.m.r. spectra.The stereochemistry of the molecule was established from 1H homonuclear decoupling and Overhauser enhancement experiments.Theveside may now be fully described by the systematic name pyran-4-carboxylic acid.Theveside, already found in two members of the Apocynaceae, is previously unreported in the Verbenaceae.
- Ford, Clive W.,Bendall, Robin M.
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p. 509 - 518
(2007/10/02)
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