Synthesis, Characterization, and In Vitro Assay of Folic Acid Conjugates of 3′-Azido-3′-Deoxythymidine (AZT): Toward Targeted AZT Based Anticancer Therapeutics

Abstract

Conjugates of three components namely folic acid, poly(ethyleneglycol) and 3 ′-azido-3 ′-deoxythymidine (AZT) are presented. Folate-PEG units were coupled to AZT to facilitate delivery of the nucleoside into the cell. A convenient separation of the polydisperse PEGylated-folic acid regioisomers produced upon conjugation is described. This is to select for the active γ-regioisomer over the inactive α-regioisomer. In vitro cytotoxicity assays were conducted against an ovarian cell line (A2780/AD) that overexpresses the folate receptor (FR) and compared to a FR free control cell line. Compared to AZT a ∼20-fold greater potency against the resistant ovarian line was observed for the conjugates.

Keywords:

• Anticancer agent
• 3′-azido-3′-deoxythymidine nucleoside
• folic acid
• isomer separation

Acknowledgments

The authors wish to thank Syracuse University, the iLEARN program, and Promega Corporation (Madison, WI) for funding. We also thank Professor Timothy J. Fairchild (Department of Exercise Science, Syracuse University) for assistance with statistical analysis and Karen L. Howard (State University of New York, ESF) and Nerissa A. Villegas (Syracuse University) for assistance obtaining MALDI-Tof mass spectra.