New selective cytotoxic diterpenylquinones and diterpenylhydroquinones

A new series of diterpenylquinone/hydroquinones has been prepared by Diels- Alder cycloaddition between three labdanic diterpenoids (myrceocommunic aci d, methyl myrceocommunate, and myrceocommunyl acetate) and p-benzoquinone o r 1,4-naphthoquinone. Influences of the quinone/hydroquinone fragment and o ther structural features, such as the different functionalities in the terp enic core, are considered in relation to the cytotoxicity toward neoplastic cells and the selectivity of these diterpenylnaphthoquinones/hydroquinones and anthraquinones. Several compounds showed IC50 values under the micromo lar level, and four of these derivatives were evaluated at the NCI screenin g panel. The results showed an important selectivity toward renal cancer li nes, identifying these compounds as a very promising group of antineoplasti cs.