Rivalosides A and B, two 19-Oxo triterpenoid saponins from Galium rivale.
Two new oleanene-type triterpene glycosides, rivaloside A (2alpha-acetoxy-3alpha-hydroxy-19-oxo-olean-12-en-28-o ic acid 28-O-beta-glucopyranosyl-(1-->6)-beta-D-glucopyranoside) (1) and rivaloside B (2alpha,3alpha-dihydroxy-19-oxo-olean-12-en-28-oic acid 28-O-beta-glucopyranosyl-(1-->6)-beta-D-glucopyranoside) (2), were isolated from aerial parts of Galium rivale. The structures were determined on the basis of spectroscopic data and chemical transformations. Under alkaline or acid hydrolysis, rivalosides A and B undergo allylic rearrangement with migration of the double bond. These compounds are the first representatives of 19-oxo substituted oleanenes, and they seem to be promising as taxonomic markers for G. rivale.
Istituto per la Chimica di Molecole di Interesse Biologico, CNR, Via Toiano 6, 80072 Arco Felice (Napoli), Italy. sderosa@icmib.na.cnr.it
S
S
De Rosa
M
M
Mitova
N
N
Handjieva
S
S
Popov
M
M
Anchev
D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D009828:Oleanolic Acid / Q000031:analogs & derivatives*; D019666:Rubiaceae / Q000737:chemistry*; D012503:Saponins / Q000737:chemistry / Q000302:isolation & purification*; D013057:Spectrum Analysis
D012503:Saponins; C413042:rivaloside A; C413043:rivaloside B; D009828:Oleanolic Acid