Long Chain Alkyl Esters of Hydroxycinnamic Acids as Promising Anticancer Agents: Selective Induction of Apoptosis in Cancer Cells.

Cancer is the major cause of morbidity and mortality worldwide. Hydroxycinnamic acids (HCAs) are naturally occurring compounds and their alkyl esters may possess enhanced biological activities. We evaluated C4, C14, C16, and C18 alkyl esters of p-coumaric, ferulic, sinapic, and caffeic acids (19 compounds) for their cytotoxic activity against four human cancer cells and also examined their effect on cell cycle alteration and apoptosis induction. The tetradecyl (1c) and hexadecyl (1d) esters of p-coumaric acid and tetradecyl ester of caffeic acid (4c), but not the parental HCAs, were selectively effective against MOLT-4 (human lymphoblastic leukemia) cells with IC50 values of 0.123 ± 0.012, 0.301 ± 0.069 and 1.0 ± 0.1 μM, respectively. Compounds 1c, 1d, and 4c significantly increased apoptotic cells in sub-G1 phase and activated the caspase-3 enzyme in MOLT-4 cells. Compound 1c was 15.4 and 23.6 times more potent than doxorubicin and cisplatin, respectively, against the drug resistant MES-SA-DX5 uterine sarcoma cells. These p-coumarate esters were several times less effective against NIH/3T3 fibroblast cells. Docking studies showed that 1c may cause cytotoxicity by interaction with carbonic anhydrase IX. In conclusion, long chain alkyl esters of p-coumaric acid are promising scaffolds for selective apoptosis induction in cancer cells.