Some new curcumin and ethylcurcumin bioconjugates with various functionalities supported on the curcumin skeleton were synthesized and evaluated for antitumor activity. Most of the newly synthesized compounds are more active than curcumin and ethyl curcumin but are less cytotoxic than the reference compound doxorubicin. Surprisingly, many of these compounds are not cytotoxic to noncancer cells.