Three New Clerodane Diterpenoids from the Bulbils of <i>Dioscorea bulbifera</i> L. var. <i>sativa</i>

Abstract

Abstract From the bulbils of Dioscorea bulbifera L. var. sativa , three new clerodane diterpenoids, bafoudiosbulbin C (=methyl (2 β ,8 α ,12 S )‐17‐oxo‐2,19 : 8,19 : 12,17 : 15,16‐tetraepoxycleroda‐3,13(16), 14‐triene‐18‐carboxylate; 1 ), bafoudiosbulbin D (=methyl (2 β ,6 β ,12 R )‐17,19‐dioxo‐2,19 : 6,17 : 8,12 : 15,16‐tetraepoxycleroda‐13(16),14‐diene‐18‐carboxylate; 2 ), and bafoudiosbulbin E (=methyl (2 β ,3 α ,4 α ,6 β ,12 R )‐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 ( 1 H, 1 H‐COSY, 13 C‐DEPT, HSQC, HMBC, and NOESY), MS analyses, as well as by comparison of their spectral data with those of related compounds.