Two Terpenoid Derivatives with Different 3/5/6/6/5‐FusedPentacyclic Skeletons fromHedyosmum orientale

Comprehensive Summary Chemical investigation of Hedyosmum orientale led to the identification of two terpenoid derivatives, dyosmunoids A and B ( 1 and 2 ) featuring two different 3/5/6/6/5‐fused pentacyclic ring systems, respectively. Compound 1 is the second natural product of this C 25 terpenoid compound class, and compound 2 is a rare dinor‐C 25 terpenoid with a peroxide bridge. Their structural elucidation was achieved by the comprehensive analysis of spectroscopic data, single‐crystal X‐ray diffraction, and ECD calculation. Putative biosynthetic pathways for compounds 1 and 2 are proposed. Compound 2 exhibited strong antimalarial activity with an IC 50 value of 0.42 μmol·L –1 .