Synthesis of UDP-GlcNAc derivatives modified at OH-4 as potential chain-terminators of chitin biosynthesis

Synthesis of 4-Azido-N-acetylhexosamine Uridine Diphosphate Donors: Clickable Glycosaminoglycans

Unnatural chemically modified nucleotide sugars UDP-4-N3-GlcNAc and UDP-4-N3-GalNAc were chemically synthesized for the first time. These unnatural UDP sugar products were then tested for incorporation into hyaluronan, heparosan, or chondroitin using polysaccharide synthases. UDP-4-N3-GlcNAc served as a chain termination substrate for hyaluronan or heparosan synthases; the resulting 4-N3-GlcNAc-terminated hyaluronan and heparosan were then successfully conjugated with Alexa Fluor 488 DIBO alkyne, demonstrating that this approach is generally applicable for labeling and detection of suitable glycosaminoglycans.

Chemoenzymatic Synthesis of 4-Fluoro-N-Acetylhexosamine Uridine Diphosphate Donors: Chain Terminators in Glycosaminoglycan Synthesis

Unnatural uridine diphosphate (UDP)-sugar donors, UDP-4-deoxy-4-fluoro-N-acetylglucosamine (4FGlcNAc) and UDP-4-deoxy-4-fluoro-N-acetylgalactosamine (4FGalNAc), were prepared using both chemical and chemoenzymatic syntheses relying on N-acetylglucosamine-1-phosphate uridylyltransferase (GlmU). The resulting unnatural UDP-sugar donors were then tested as substrates in glycosaminoglycan synthesis catalyzed by various synthases. UDP-4FGlcNAc was transferred onto an acceptor by Pastuerella multocida heparosan synthase 1 and subsequently served as a chain terminator.

Synthesis of N-acetyl Glucosamine Analogs as Inhibitors for Hyaluronan Biosynthesis

Elevated hyaluronan expression is a hallmark of many types of cancer. Therefore, inhibition of hyaluronan biosynthesis can potentially slow the growth of tumor cells. Herein, we explore a chain termination strategy to reduce hyaluronan synthesis by tumor cells. Several analogs of glucosamine were prepared, which contained modifications at the C-3 positions. These analogs can possibly cap the nonreducing end of a growing hyaluronan chain, thus lowering the amount of hyaluronan synthesized. Upon incubation with pancreatic cancer cells, a fluorine-containing glucosamine analog was found to exhibit significant inhibitory activities of hyaluronan synthesis. Furthermore, it drastically reduced the proliferation of cancer cells.

Synthesis of sugar nucleotides by application of phosphoramidites

A new method for the construction of pyrophosphates is reported based on the coupling of a sugar phosphate and a nucleoside phosphoramidite. The in situ formed phosphate-phosphite intermediate was subsequently oxidized with tBuOOH. Three UDP-N-acetylglucosamine derivatives were prepared using this one-pot procedure in good yields.

Synthesis of glucose derivatives modified at the 4-OH as potential chain-terminators of cellulose biosynthesis; herbicidal activity of simple monosaccharide derivatives

A series of D-glucose derivatives that have been modified at C-4 were synthesised from D-galactose as potential chain terminators of cellulose biosynthesis. Two compounds displayed herbicidal activity in pre-emergence tests and in addition a cell expansion assay at higher concentrations revealed symptomology of a third compound that was indicative of inhibition of cellulose biosynthesis.

Synthesis of UDP-glucose derivatives modified at the 3-OH as potential chain terminators of beta-glucan biosynthesis

A series of UDP-D-glucose derivatives and precursors that have been modified at C-3 were synthesised from D-glucose as potential chain terminators of beta-glucan biosynthesis. None of the UDP-derivatives or the precursors tested displayed significant anti-fungal activity in a series of germination assays on the dermatophyte Trichophyton rubrum.