Three New ent-Labdane Diterpenoids from the Wood of Excoecaria agallocha LINN.

An extensive study of metabolites present in Excoecaria agallocha LINN. led to the isolation of three new ent-labdane-type diterpenoids, named agallochaexcoerins A-C (1-3). besides three known compounds. The skeleton present in compound I is rather unusual, containing of a seven-membered lactone. The structures were elucidated on the basis of spectroscopic studies and comparison with known related compounds. The isolated compounds 1-6 were not active against Raw 264.7 (macrophage-like), K 562 (leukemia), and COLO 205 (colon) human carcinoma cell lines.