A new ent-kaurane diterpene from Isodon henryi

One new ent-Kaurane diterpenoid (1) was isolated from the ethyl acetate fraction of Isodon henryi. Along with ten diterpenoids (2-11) were isolated from this plant for the first time, including six 7,20-epoxy diterpenoids, three enmenol-type diterpenoids and one 6,7-seco-ent-kaurene diterpenoid. Their structures were elucidated by 1 D and 2 D NMR, confirmed by HRESIMS and electronic circular dichroism analyses. Furthermore, the cytotoxicities of twelve compounds were investigated in five human cancer cell lines, including A2780, BGC-823, HCT-116, HepG2 and HeLa. And the IC50 values of these diterpenoids ranged from 2.1 to 88.8 mu M in the tested cell lines. Based on the molecular structures of 12 compounds and the bioassay results, it suggests that alpha,beta-unsaturated pentanone is the cytotoxic active site of 7,20 epoxy ent-kaurane diterpenoid, but it does not contribute much to enmenol-type diterpenoid.

Automated summary

A new ent-kaurane diterpenoid was isolated from Isodon henryi, along with ten other diterpenoids, including six 7,20-epoxy and three enmenol-type compounds. The cytotoxicities of these compounds were evaluated in various cancer cell lines, revealing potential anti-cancer properties.