BIOSYNTHESIS OF IRIDOID GLUCOSIDES IN HEBENSTRETIA DENTATA

Article abstract of DOI:10.1016/S0031-9422(00)97538-1

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.