Synthesis, Transport and Pharmacokinetics of 5′-Amino Acid Ester Prodrugs of 1-β-d-Arabinofuranosylcytosine

Abstract

Cytarabine (1-beta-d-arabinofuranosylcytosine, ara-C, 1) suffers from low oral bioavailability due to low intestinal membrane permeability and poor metabolic stability, and intravenous infusion is usually adopted as the clinical standard dosing administration. To develop an oral alternative for 1 and utilize the intestinal oligopeptide transporter 1 (PepT1), a series of 5'-amino acid ester derivatives of 1 was synthesized to clarify which modification was the most suitable to increase the oral bioavailability of 1. Their apical-to-basolateral permeability across Caco-2 cells and the antiproliferative activity with HL-60 cells were screened. 5'-Valyl prodrug 2 demonstrated the highest permeability and was selected for further study. Glycylsarcosine (gly-sar, a typical substrate of PepT1) uptake by Caco-2 cells can be inhibited by 2 in a concentration-dependent manner, and IC(50) for 2 was 2.18 +/- 0.12 mM. The uptake of 2 was markedly increased in the long-term leptin-treated Caco-2 cells compared with the control Caco-2 cells, and was significantly inhibited by the excess of gly-sar, but not by l-valine. A dose-proportional pharmacokinetics was observed in rats when 5, 15, 30 mg/kg doses of 2 (calculated as 1) were orally administered. The oral absolute bioavailability of 1 was 60.0% and 21.8% after 2 and 1 were orally administered to rats 30 mg/kg, respectively. Following oral administration of 15 mg/kg, the absorption and bioactivation of 2 were extensive and rapid, over 98% of prodrug hydrolysis occurring before appearance in the portal vein. The in vivo dispositions of 1-beta-D-arabinofuranosyluracil (ara-U), a deaminated product of 1, were investigated. Oral administration of 2 resulted in an increased 1/ara-U ratio (2.76) in the blood, much higher than that (1.25) after 1 orally taken. Overall, these results demonstrated that the PepT1-mediated absorption of 2 and the increased metabolic stability resulted in a dramatic increase in the oral bioavailability of 1 in rats and further corroborated the thought that prodrug design strategy targeting intestinal PepT1 was an important and promising strategy to improve oral bioavailability of poorly absorbed drugs.

The Concise Guide toPHARMACOLOGY2013/14: Transporters

“…PepT1 has also been exploited to allow delivery of therapeutic pro-drugs, such as those for zidovudine 256, sulpiride 269 and cytarabine 266.…”

Hijacking Solute Carriers for Proton-Coupled Drug Transport

“…In mice, oral bestatin accumulates in xenografts of PepT1-transfected HeLa cells and inhibits the growth of these tumors (74). Pro-drugs of floxuridine and cytarabine may also be transported by PepT1 (97,117) (FIGURE 1A).…”

Synthesis of CDDO–Amino Acid–Nitric Oxide Donor Trihybrids as Potential Antitumor Agents against Both Drug-Sensitive and Drug-Resistant Colon Cancer

“…[35][36][37][38][39][40] Thus, the differential expression of PepT1 has been utilized for design and synthesis of selective anticancer agents, including the PepT1-targeting dihybrids of amino acid with OA, floxuridine, gemcitabine, cytarabine, and gold (III)-dithiocarbamato, respectively. [40][41][42][43][44] In this context, we hypothesized that CDDO-amino acid-NO donor trihybrids could be effectively transported to cancer cells by the PepT1 to exert potent cytotoxicity against both drug-sensitive and drug-resistant colon cancer cells. Accordingly, we synthesized 5 trihybrids 4a-q by coupling the carboxyl group of CDDO with phenylsulfonyl-substituted furoxan through different amino acids, respectively, and evaluated their bioactivity in vitro and in vivo.…”