New iridal-type triterpenoid analogues with 6/5/6-fused carbon skeleton from the rhizomes of Belamcanda chinensis

Abstract

Five new iridal-type triterpenoid derivatives with 6/5/6 tricyclic ring skeleton (1–5) were obtained from the rhizomes of Belamcanda chinensis. Their structures were determined on the basis of detailed spectroscopic data and ECD calculation. Compounds 1–5 possessed the same 6/5/6-fused carbon skeleton as Belamchinenin A, which further enriched this kind of iridals. In vitro bioassay, compounds 2 and 3 exhibited 51.95 and 54.52% inhibitory activities, respectively, against Fe2+/cysteine-induced liver microsomal lipid peroxidation at a concentration of 10 μM. A putative biogenetic pathway for compounds 1–5 was proposed.