On the Influence of the Rhodamine Substituents Onto the Cytotoxicity of Mitocanic Maslinic Acid Rhodamine Conjugates

Maslinic acid was converted via a di-acetylated piperazinyl amide into rhodamine conjugates differing in their alkyl moieties. These conjugates were submitted to cytotoxicity assays employing a panel of human tumor cell lines. These conjugates held high cytotoxicity but also some selectivity especially for A2780 cells. Thereby, a propyl substituted rhodamine conjugate showed EC50 values as low as EC50 = 0.01 μM and was approx. 15 times more cytotoxic for the cancer cells than for non-malignant fibroblasts (NIH 3 T3). Cytotoxicity obviously parallels the lipophilicity of the residue and suggests - since the compounds act as mitocanes - an interaction of the conjugates with the inner mitochondrial membrane.