Synthesis and Antiproliferative Activity of Conjugates of Anthracycline Antibiotics with Sesquiterpene Lactones of the Elecampane

The daunorubicin and doxorubicin anthracycline antibiotics were modified with the Inula helenium L. sesquiterpene lactones (alantolactone, isoalantolactone, and alloalantolactone) and with their epoxy derivatives. Antiproliferative properties of these conjugates were studied on tumor and normal cell lines. The daunorubicin conjugates with the sesquiterpene lactones (isoalantolactone, allantolactone, and alloalantolactone) and with their epoxy derivatives were found to exhibit the higher activity against human tumor cell lines than the corresponding doxorubicin conjugates. The daunorubicin conjugate with epoxyisoalantolactone proved to be the most effective compound, because it was more cytotoxic than daunorubicin towards a number of cell lines, including those daunorubicin-resistant, and did not affect normal human cells.