Synthesis and Antiproliferative Evaluation of Novel 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 N-glycosidation with a nucleobase or 1,3-dipolar cycloaddition with N9 and N7-propargyl-6-chloropurines, respectively. N-Propargyl glucuronamide-based N9-linked 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-dimethylamino purine 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 N9-β-linked 6-chloropurine moiety was the most active compound against MCF-7 cells (GI50 = 11.9 μM) while a related α-(purinyl)methyltriazole nucleoside comprising a N7-linked 6-chloropurine moiety exhibited the highest activity against K562 cells was (GI50 = 8.0 μM). Flow cytometry analysis and immunoblotting analysis of apoptosis-related proteins in K562 cells treated with the N-propargyl 3-O-dodecyl glucuronamide-based N9-linked 6-chloropurine nucleoside indicated that it acts via apoptosis induction.