1-bD-Arabinofuranosylcytosine-5 9-alkylphosphonophosphates and diphosphates : new orally active derivatives of araC

ara-Cytidine-5 9 -alkylphosphonophosphates and the corresponding -diphosphates were found to be cytostatically active in vitro against the human mammary epithelial cell line H184 A1N4 and the human mammary tumor cell line MaTu. Our results indicate that the replacement of the diphosphate by the phosphonophosphate group has no influence on antiproliferative activity in this case. The compounds were more active than the corresponding cytidine phospholipid conjugates and related compounds lacking a cytostatically active nucleoside, the ara-C prodrug Cytoros, and were slightly less active than ara-C. The cytostatic effect was prevented by 2 9 deoxycytidine indicating their action as prodrugs of ara-C. In contrast to ara-C, they increase [Ca 2 1 ] 1 in H184 A1N4 cells, pointing to a different mechanism of action in addition to their prodrug effect. In combination with phospholipid analogs, synergistic effects could be observed. Further studies within the disease-oriented in vitro Anticancer Screening Program of the National Cancer Institute show selectivity for certain cancer cell lines. The hexadecyl derivatives revealed a significant antitumor activity in vivo against the murine lymphatic leukemia P 388 cells being equally potent or even superior to ara-C. In contrast to ara-C, they were found to be orally active. Side effects measured as leukopenia and body weight reduction were less pronounced than with the parent drug. —Brachwitz, H. , J. Bergmann, I. Fichtner, Y. Thomas, C. Vollgraf, P. Langen, and W. E. Berdel. 1b D -Arabinofuranosylcytosine-5 9 -alkylphosphonophosphates and diphosphates: new orally active derivatives of ara-C. J. Lipid Res. 1998. 39: 162–172. Supplementary key words ara-C derivatives • alkylphospholipids • calcium • antiproliferative activity • in vivo studies • in vitro studies • drug combination • phosphonophosphates 1b D -Arabinofuranosylcytosine (ara-C) has been shown to be an effective anticancer drug for the treatment of human acute myeloblastic and lymphoblastic leukemia (1). In clinical use, however, the compound is rapidly converted to the inert metabolite 1b d arabinofuranosyluracil by the action of cytidine deaminase (2). In attempts to avoid deamination of ara-C and to enhance cellular uptake, several types of prodrugs have been synthesized. ara-Cytidine-phospholipid conjugates like 1b d -arabinofuranosylcytosine-5 9 -diphosphate-rac-1-S-octadecyl-2-O-palmitoyl-1-thioglycerol (Cytoros) have been prepared and have shown therapeutic efficacy exceeding the activity of ara-C in some cases (3). Recently, we have found that some analogs of the naturally occurring cytidinediphosphate-diacylglycerol (CDP-DAG) as well as similarly structured deoxycytidine, thymidine, and adenosine derivatives, possessing a special phospholipid component exhibit antitumor activity though lacking a cytostatically active nucleoside (4–7). Apparently, the effects are mainly or exclusively attributed to the phospholipid component. Structure– activity studies with these compounds have shown that derivatives containing one long-chain alkyl group in the glycerol were cytostatically active whereas diacylalkylacyl-, and dialkylglycero derivatives had no effect (6). Analogs in which the alkylglycerol group was substituted by a long-chain alkyl group have also proved to be effective, indicating that the presence of a glycerol backbone is not a necessary prerequisite for cytotoxicity of these compounds (5, 7). Further, by replacing the diphosphate group by a phosphonophosphate group, a clear increase in effectiveness could be observed (6, 7). In this context it was of interest to prepare new ara-C Abbreviations: ara-C, 1b D -arabinofuranosylcytosine; [Ca 2 1 ] i , concentration of intracellular calcium; C 16 Cl-GPC, 1-O-hexadecyl-2chloro-2-deoxyglycero-3-phosphocholine; C 16 -NAc-PS, hexadecylphosphoN -acetylL -serine; C 16 P-CMP, cytidine-5 9 -hexadecylphosphonophosphate; CDP-DAG, cytidine-5 9 -diphosphate-diacylglycerol; FAB MS, fast atom bombardment mass spectrometry; ESI MS, electrospray ionization mass spectrometry; TLC, thin-layer chromatography. 1 To whom correspondence should be addressed. by gest, on S etem er 7, 2017 w w w . j.org D ow nladed fom