Isoforrethins A-D, four ent-abietane diterpenoids from Isodon forrestii var. forrestii

Abstract

Four new ent-abietane diterpenoids, isoforrethins A-D (1-4), were isolated from the aerial parts of Isodon forrestii var. forrestii by a variety of chromatographic techniques. Their structures were elucidated on the basis of spectroscopic data interpretation, single crystal X-ray diffraction, and quantum chemical calculation. All of these compounds were evaluated for their cytotoxicity against five human tumor cell lines (HL-60, SMMC-7721, A-549, MCF-7 and SW-480), and compound 4 showed significant inhibitory activities against SMMC-7721, A-549, MCF-7, and SW-480.

Keywords: Cytotoxicity; Isodon forrestii var. forrestii; Quantum chemical calculation; ent-Abietane diterpenoids.