Synthesis and Antiproliferative Evaluation of d-Glucuronamide-Based Nucleosides and (Triazolyl)methyl Amide-Linked Pseudodisaccharide Nucleosides

The synthesis and antiproliferative evaluation of novel d-glucopyranuronamide-containing nucleosides is described. Based on our previously reported anticancer d-glucuronamide-based nucleosides, new analogues comprising N/O-dodecyl or N-propargyl substituents at the glucuronamide unit and anomerically-N-linked 2-acetamido-6-chloropurine, 6-chloropurine or 4-(6-chloropurinyl)methyl triazole motifs were synthesized in 4-6 steps starting from acetonide-protected glucofuranurono-6,3-lactone. The methodologies were based on the access to N-substituted glycopyranuronamide precursors, namely 1,2-O-acetyl derivatives or glucuronoamidyl azides for further nucleobase N-glycosylation or 1,3-dipolar cycloaddition with N-9- and N-7-propargyl-6-chloropurines, respectively. N-Propargyl glucuronamide-based N-9-purine nucleosides were converted into (triazolyl)methyl amide-6,6-linked pseudodisaccharide nucleosides via cycloaddition with methyl 6-azido-glucopyranoside. A CuI/Amberlyst A-21 catalytic system employed in the cycloaddition reactions also effected conversion into 6-dimethylaminopurine nucleosides. Antiproliferative evaluation in chronic myeloid leukemia (K562) and breast cancer (MCF-7) cells revealed significant effects exhibited by the synthesized monododecylated purine-containing nucleosides. A N-propargyl 3-O-dodecyl glucuronamide derivative comprising a N-9-beta-linked 6-chloropurine moiety was the most active compound against MCF-7 cells (GI(50)=11.9 mu M) while a related alpha-(purinyl)methyltriazole nucleoside comprising a N-7-linked 6-chloropurine moiety exhibited the highest activity against K562 cells (GI(50)=8.0 mu M). Flow cytometry and immunoblotting analysis of apoptosis-related proteins in K562 cells treated with the N-propargyl 3-O-dodecyl glucuronamide-based N-9-linked 6-chloropurine nucleoside indicated that it acts via apoptosis induction.