Abietane diterpenes induce cytotoxic effects in human pancreatic cancer cell line MIA PaCa-2 through different modes of action

► Abietane diterpenes preferentially inhibit topoisomerase I. ► A new binding mode is described. ► Cell cycle is influenced in the G1/G0 or the S-phase. ► Induction of DNA damage is observed in the comet assay.