Triterpene saponins and iridoid glucosides from Galium rivale

Three new glycosides of the oleanene-type triterpenes, rivalosides C-E (1-3 ), along with three known triterpene saponins, momordin IIb (4) and rivalos ides A-B (5-6), and five known iridoid glucosides: monotropein, scandoside, deacetylasperulosidic acid, geniposidic acid and asperulosidic acid, were isolated from aerial parts of Galium rivale. The structures of the new comp ounds were elucidated by spectral methods and chemical means as 2 alpha-ace toxy-3 alpha,19 alpha-dihydroxy-olean-12-en-28-oic acid 28-O-beta-D-glucopy ranosyl-(1 --> 6)-beta-D-glucopyranoside, 2 alpha,3 alpha,19 alpha-trihydro xy-olean-12-en-28-oic acid 28-O-beta-D-glucopyranosyl-(1 --> 6)-beta-D-gluc opyranoside and 3-O-beta-D-glucuronopyranosyl-24-hydroxy-olean-12-en-28-oic acid 28-O-beta-D-glucopyranoside, for rivalosides C-E, respectively. The t axonomic significance of the rivalosides in G. rivale was discussed. (C) 20 00 Elsevier Science Ltd. All rights reserved.