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 Rf values as well as by their haemolytic activity on blood agar. After hydrolysis, the
chemical reactions and Rf 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.
Grindelia robusta
- Asteraceae - haemolytic activity - antibiotic activity - structural elucidation
- grindeliasapogenin D - 2β,3β,16α,23-tetrahydroxyoleanan-28 - 13β-olide - bayogenin
- oleanolic acid
