TRITERPENOIDS FROM BUPLEURUM FALCATUM L .3. ISOLATION OF GENUINE SAPOGENINS SAIKOGENINS E F AND G

The crude saponins from the root of Bupleurum falcatum L. previously yielded, on acid hydrolysis, saikogenins A, B, C and D (triterpenoids having conjugated dienes) together with longispinogenin. Examination of the saponins demonstrates that saikogenins A, B and C are artifacts formed during the acid hydrolysis and that the saponin leading to saikogenin D has already suffered transformation during the functionation of the saponins by the effects of acidic components. Extraction of the plant with alcohol containing pyridine gives the saponins showing no UV absorption due to a heteroannular diene. The newly obtained saponins, on repeated degradations by sodium periodate oxidation and alkaline treatment, afford three new triterpenoids, sakogenins E, F and G, which are shown to be genuine sapogenins corresponding to the previously obtained saikogenins A, B, C and D. The structure of saikogenins E, F and G has been elucidated as 13β,28-epoxyloean-11-ene-3β,16β-diol (Ia), -3β,16β,23-triol (IIa) and -3β,16α,23-triol (IIIa), respectively. Some modifications for the degradation of the saponins are also investigated. © 1968.