UNSATURATED E-RING TRITERPENES FROM RUBUS-PINFAENSIS

Two new isomeric unsaturated E-ring pentacyclic tritelpenoids have bee n isolated from the roots of Rubus pinfaensis. These triterpenes, gluc osides of 2 alpha,3 beta,23-trihydroxyurs-12-en-28-oic acids with addi tional Delta(18) or Delta(19) unsaturation, were hydrolysed to the pre viously unreported pinfaenoic and isopinfaenoic acids, which, on acety lation and methylation, were converted into methyl triacetoxy-esters ( methyl 2 alpha,3 beta,23-triacetoxyursa-12,18-or -12,19-dien-28-oates) , allowing purification and characterization by C-13 and H-1 NMR techn iques. The possibility of these triterpenoids arising as artefacts of the isolation process has been addressed.