Constituents of the Fruit of Pseudopanax arboreum (Araliaceae)

Abstract

Saponification and methylation of the acidic fraction of an extract of the fruit of the New Zealand tree Pseudopanax arboreum has led to the isolation of a series of ring-A substituted and ring-A seco triterpenoids possessing oleanane or ursane skeletons. These include methyl 3-oxo-24-norurs-12-en-28-oate (1), dimethyl 4-oxo-3,24-dinor- 2,3-secours-12-ene-2,28-dioate (7), methyl 2α,3α,23-trihydroxyolean-12- en-28-oate (10), the ε-lactone of 23-hydroxy-4,17-dimethoxycarbonyl- 2,3-secours-12-en-2-oic acid (15), trimethyl 24-nor-2,3-secours-12-ene- 2,3,28-trioate (20), methyl 2-hydroxy-3-oxo-24-noroleana-1,4,12-trien- 28-oate (26), and methyl 2-hydroxy-3-oxo-24-norursa-1,4,12-trien-28- oate (27) whose parent acids have not hitherto been obtained as natural products. Other compounds are methyl 2α,3α-dihydroxyolean-12-en-28-oate (9), methyl 2α,3α-dihydroxyurs-12-en-28-oate (23), methyl asiatate (24), methyl arjunolate (13), the methoxy artefact (12), and the aryl- substituted methyl cinnamates (28), (29), (30) and (31). Neutral constituents include the esters (1), (9) and (10), stigmasterol and the sesquiterpene spathulenol (32).