Biomimetic synthesis of an antitumour indole sesquiterpene alkaloid, 12-epi-ent-pentacyclindole

Biomimetic synthesis of 12-epi-ent-pentacyclindole 7, using as key step the cyclization of 12-epi-ent-polyalthenol acetate has been carried out. This way, the structure and absolute configuration of the natural product pentacyclindole 1 has been confirmed. The synthesized indole sesquiterpenes 7, 11 and 12 show cellular proliferation inhibition of a number of human leukaemic and solid tumour cell lines.

A biomimetic synthesis of 12-epi-ent-pentacyclindole has been carried out, using ent-halimic acid as starting material and 12-epi-ent-polyalthenol as key intermediate. The synthesized indole sesquiterpenes inhibit proliferation of several human tumour cells, including leukaemic and solid tumour cells, with an IC50 in the range of 25 μM.