Synthesis, anticancer activities, and cellular uptake studies of lipophilic derivatives of doxorubicin succinate.

A number of lipophilic 14-substituted derivatives of doxorubicin were synthesized through conjugation of doxorubicin-14-hemisuccinate with different fatty amines or tetradecanol to enhance the lipophilicity, cellular uptake, and cellular retention for sustained anticancer activity. The conjugates inhibited the cell proliferation of human leukemia (CCRF-CEM, 69-76%), colon adenocarcinoma (HT-29, 60-77%), and breast adenocarcinoma (MDA-MB-361, 66-71%) cells at a concentration of 1 μM after 96-120 h of incubation. The N-tetradecylamido derivative of doxorubicin 14-succinate (10) exhibited consistently comparable antiproliferative activity to doxorubicin in a time-dependent manner (IC(50) = 77 nM in CCRF-CEM cells). Flow cytometry analysis showed a 3-fold more cellular uptake of 10 than doxorubicin in SK-OV-3 cells. Confocal microscopy revealed that the conjugate was distributed in cytoplasmic and perinuclear areas during the first 1 h of incubation and slowly relocalized in the nucleus after 24 h. The cellular hydrolysis study showed that 98% of compound 10 was hydrolyzed intracellularly within 48 h and released doxorubicin.