Triterpenoidsapogenine in der Gattung Grindelia

Abstract

A saponin fraction has been isolated from the ethanolic extract of Grindeliae herba. The saponin fraction showed strong haemolytic activity. The saponins were detected after separation on TLC by their color reactions and R_f values as well as by their haemolytic activity on blood agar. After hydrolysis, the chemical reactions and R_f values of the sapogenins were described. The main sapogenin was isolated by preparative chromatography and its structure was elucidated by mass, ¹H-NMR, ¹³C-NMR, IR, and UV spectra. The compound is a new natural triterpenoid sapogenin lactone and is named grindeliasapogenin D. Spectral evidence is presented to establish its structure as 2β,3β,16α,23-tetrahydroxyoleanan-28,13β-olide. Two further sapogenins present in small amounts were identified chromatographically as oleanolic acid and bayogenin using authentic reference substances. The aerial parts of Grindelia robusta Nutt. and G. lanceolata Nutt. (Asteraceae) (as well as two commercial extracts) were also investigated with respect to their saponin fraction. The 3 sapogenins mentioned above were detected in all samples. The antibiotic potency of the crude drug is not associated with the saponin fraction but is at least partially due to the resin fraction.

Key words

Grindelia robusta - Asteraceae - haemolytic activity - antibiotic activity - structural elucidation - grindeliasapogenin D - 2β,3β,16α,23-tetrahydroxyoleanan-28 - 13β-olide - bayogenin - oleanolic acid