Enhanced cellular uptake of Ara-C via a peptidomimetic prodrug, L-valyl-ara-C in Caco-2 cells

Abstract

This study aimed to investigate the gastrointestinal stability and the cellular uptake characteristics of L-valyl-ara-C, a peptidomimetic prodrug of ara-C (cytarabine). After the synthesis of Lvalyl-ara-C via the incorporation of L-valine into the N4-amino group of the cytosine ring in ara-C, the gastrointestinal stability of L-valyl-ara-C was examined using artificial gastric juice and artificial intestinal fluids. The cellular uptake characteristics of L-valyl-ara-C were also examined in Caco-2 cells. The disappearance half-life of L-valyl-ara-C was 2.2 h in artificial gastric juice, while the degradation of L-valyl-ara-C was negligible in artificial intestinal fluid and also in the supernatant above the Caco-2 cell monolayer during the 2-h incubation. The cellular accumulation of L-valyl-ara-C was 5-fold higher than that of ara-C in Caco-2 cells. Furthermore, the cellular uptake of L-valyl-ara-C did not increase proportionally to the increase in drug concentration. The cellular accumulation of L-valyl-ara-C was significantly reduced in the presence of uridine, p-aminohippurate, tetraethylammonium and small dipeptides, while it was not changed in the presence of L-valine and benzoic acid, suggesting that L-valyl-ara-C could interact with multiple uptake transporters, including peptide transporters, organic anion and cation transporters and nucleoside transporters, but might not interact with amino acid transporters. In conclusion, L-valyl-ara-C could be effective to improve the oral absorption of ara-C via the carrier-mediated transport pathway.

Pharmacokinetic characteristics of L-valyl-ara-C and its implication on the oral delivery of ara-C

“…In addition, it may also be possible to incorporate prodrug strategies that could reduce undesirable side effects such as toxicity, and improve therapeutic action into such oral alternatives. In our previous studies, L-valyl-ara-C appeared to be beneficial in enhancing the cellular uptake of ara-C in Caco-2 cells [9] . However, in the present study, prodrug itself exhibited far less antiproliferative activity than ara-C in AML-2 and L1210 cells and thus, the rate of conversion of the prodrug to the pharmacologically-active parent drug after membrane transport would determine the therapeutic effectiveness of L-valyl-ara-C.…”

“…Recently, our group synthesized the L-valyl-ara-C by masking the N4-amino group of the cytosine ring in ara-C with L-valine in order to enhance the intestinal absorption of ara-C, and evaluated the cellular uptake characteristics of L-valyl-ara-C in Caco-2 cells [9] . Compared to ara-C, L-valylara-C appeared to be stable in the intestinal lumen and exhibited 5 fold higher cellular uptake via the carrier-mediated transport pathways.…”

“…Synthesis of L-valyl-ara-C Prodrug was synthesized as previously described by Cheon et al [9] , and identified by the 1 H-NMR, 13 C-NMR and EI-MS spectrometers. In vitro stability study Stabilities of L-valyl-ara-C were evaluated at 37 °C by incubating a drug solution (10 µmol/L) in the fresh plasma and cell homogenates.…”

Selective cancer targeting with prodrugs activated by histone deacetylases and a tumour-associated protease

“…Notably, this approach is potentially advantageous, because the simple smallmolecule masking group could be readily applied to many other cytotoxic agents, including chemotherapeutic drugs currently used in the clinic. For example, amide coupling-based prodrugs of gemcitabine and cytarabine were developed by masking their amino group 37,38 . Thus, introduction of the Boc-Lys(Ac) group to their amino group should be technically feasible for evaluation of their improved efficacy.…”

Novel liver-specific cholic acid-cytarabine conjugates with potent antitumor activities: Synthesis and biological characterization

“…Behenoyl-Ara-C (Enocitabine, 4), one of the N 4 -acyl derivatives of saturated fatty acids, has been found to be superior to its parent compound, cytarabine, likely because of the resistance to cytidine deaminase and the liberation of Ara-C over a period of time [8] . N 4 -peptidyl-Ara-C, like L-valyl-Ara-C, was reported to increase cellular uptake of cytarabine through the involvement of various transporters [10] . Relatively high activity of cytarabine conjugates was achieved through the coupling of amino groups of cytarabine with carboxyl groups of polysaccharide molecules (eg, polygalacturonic acid (PGA) and carboxymethylated yeast beta-D-glucan (CMG)); the in vitro antileukemic activity of these www.chinaphar.com Chen DQ et al Acta Pharmacologica Sinica npg conjugates was comparable or higher than the activity of nonconjugated/free cytarabine combined with a polysaccharide [11] ( Figure 2).…”