Isolation and Structure of Eucosterol and 16 β‐Hydroxyeucosterol, Two Novel Spirocyclic Nortriterpenes, and of a New 24‐ Nor‐5α‐chola‐8, 16‐diene‐23‐oic Acid from Bulbs of Several Eucomis Species

Eucosterol and 16 β‐hydroxy‐eucosterol which have been isolated from several Eucomis species have been shown to be (23 S )‐17,23‐epoxy‐3β,31‐dihydroxy‐27‐nor‐5α‐lanost‐8‐ene‐15,24‐dione ( 1 ) and (23 S )‐17,23‐epoxy‐3β,16β,31‐trihydroxy‐27‐nor‐5α‐lanost‐8‐ene‐15,24‐dione ( 2 ) by chemical transformations and spectral data. The spiro‐fused furanoic ether linkage of both metabolites represents a novel structural element for natural nortriterpenes. The structure of another metabolite ( 16 ), 3β‐hydroxy‐4β‐hydroxymethyl‐4,14α‐dimethyl‐15‐oxo‐24‐nor‐5α‐chola‐8,16‐diene‐23‐oic acid, from Eucomis autumnalis (Mill.) Chitt. was elucidated by chemical correlation of its methyl ester 17 with a degradation product of eucosterol ( 1 ).