Synthesis and biological evaluation of monosaccharides directed towards influencing glycoconjugate biosynthesis in culture

Cell-surface glycosaminoglycans play a major role in the healthy functioning of cells. Alterations in these glycoconjugates are associated with the pathology of diseased cells. The purpose of the present study was to synthesize and evaluate monosaccharide analogs of the repeating disaccharide unit of glycosaminoglycans which, on the basis of their structures, would interfere with glycosaminoglycan biosynthesis.; 4-Deoxy analogs of 2-acetamido-2-deoxy-D-glucose, including 2-acetamido-1,3,6-tri-O-acetyl-2,4-dideoxy-D- xylo-hexopyranose (42), 2-acetamido-1,3,6-tri- O-acetyl-2,4-dideoxy-4-fluoro-D-galactopyranose ( 68), and 2-acetamido-1,3,6-tri-O-acetyl-2,4-dideoxy-4-fluoro- D-glucopyranose (81) were synthesized and evaluated as inhibitors of glycosaminoglycan and total protein biosynthesis. Each of these analogs, at 1.0 mM, demonstrated a significant reduction of incorporation (∼5% of control) of radiolabels into isolated glycosaminoglycans. Compounds 42 and 68 also demonstrated a moderate reduction (∼60% of control) of protein synthesis at 1.0 mM, but not at 0.1 mM. These results suggest a dual mechanism of inhibition for compounds 42 and 68, at 1.0 mM, in which the inhibitory effects are directed partly towards the inhibition of glycosaminoglycan synthesis and partly towards the inhibition of protein synthesis. Supporting evidence was established by the determination of the glycosaminoglycan chain size and by the supplementation of the cell culture medium with uridine.; Two analogs of D-glucuronic acid. namely methyl (methyl 2,3-di-O-acetyl-4-chloro-4-deoxy-β-D-galactopyranosid)uronate (85) and methyl 1,2,3,4-tetra-O-acetyl- D-glucopyranuronate (91), were synthesized and evaluated as inhibitors of glycosaminoglycan synthesis, but demonstrated no biological activity up to 1.0 mM.; A 1-deoxy analog of 2-acetamido-2-deoxy-D-glucose, namely 2-acetamido-3,4,6-tri-O-acetyl-1,5-anhydro-2-deoxy- D-glucitol (96), was synthesized and demonstrated a significant reduction of only D-[3H]glucosamine incorporation at 1.0 mM to 19% of control, without affecting cellular protein synthesis. This analog is proposed to inhibit the enzymatic conversion of D-glucosamine into a UDP-sugar, a process which represents an alternative route of inhibition of glycosaminoglycan biosynthesis, as compared to compound 42.; 4-Deoxy analogs of 2-acetamido-2-deoxy-D-xylose, for example, 2-acetamido-1,3-di-O-acetyl-2,4-dideoxy-L- threo-pentopyranose (124), were evaluated but demonstrated no biological activity, suggesting that the C-6 substituent is-important for biological activity.; A radiolabeled analog. namely methyl 2-acetamido-2,4-dideoxy-6-tritio-β- D-xylo-hexopyranoside (113). was synthesized and a radiolabeled unit derived from compound 113 was found to be incorporated into cell-surface glycosaminoglycans, a result which provides corroborating evidence that the 4-deoxy analogs can serve as substrates for the incorporation into glycosaminoglycans.