Noroleanane saponins from Celmisia petriei

Two biologically active noroleanane saponins from Celmisia petriei are identified as 3-O-(α-l-arabinopyranosyl (1 → 6)-β-d-glucopyranosyl (1 → 2)-α-l-arabinopyranosyl), 2β,17,23-trihydroxy-28-norolean-12-en-16-one and its 2″-O-acetyl derivative. ¹³C NMR and T₁ measurements allowed the determination of the sugar sequence and the majority of the linkage positions, but gave ambiguous results for the inner arabinose sugar. The structure of camellenodiol is revised to 3β,17-dihydroxy-28-norolean-12-en-16-one.