Three New Clerodane Diterpenoids from the Bulbils of Dioscorea bulbifera L. var. sativa

Abstract From the bulbils of Dioscorea bulbifera L. var. sativa, three new clerodane diterpenoids, bafoudiosbulbin C (=methyl (2β,8α,12S)‐17‐oxo‐2,19 : 8,19 : 12,17 : 15,16‐tetraepoxycleroda‐3,13(16), 14‐triene‐18‐carboxylate; 1), bafoudiosbulbin D (=methyl (2β,6β,12R)‐17,19‐dioxo‐2,19 : 6,17 : 8,12 : 15,16‐tetraepoxycleroda‐13(16),14‐diene‐18‐carboxylate; 2), and bafoudiosbulbin E (=methyl (2β,3α,4α,6β,12R)‐17,19‐dioxo‐2,19 : 3,4 : 6,17 : 8,12 : 15,16‐pentaepoxycleroda‐13(16),14‐diene‐18‐carboxylate; 3) were isolated, together with the known compounds bafoudiosbulbins A and B, 3‐O‐β‐D‐glucopyranosyl‐β‐sitosterol, and 6′‐stearoyl‐3‐O‐β‐D‐glucopyranosyl‐β‐sitosterol. Their structures were established by high‐field NMR techniques (1H,1H‐COSY, 13C‐DEPT, HSQC, HMBC, and NOESY), MS analyses, as well as by comparison of their spectral data with those of related compounds.