Synthesis of Azide-Modified Chondroitin Sulfate Precursors: Substrates for "Click"-Conjugation with Fluorescent Labels and Oligonucleotides

: Jadhav S, Gulumkar V, Deshpande P, Coffey ET, Lonnberg H, Virta P

Publisher: AMER CHEMICAL SOC

: 2018

: Bioconjugate Chemistry

: BIOCONJUGATE CHEMISTRY

: BIOCONJUGATE CHEM

: 29

: 7

: 2382

: 2393

: 12

: 1043-1802

DOI: https://doi.org/10.1021/acs.bioconjchem.8b00317(external)

a Azidopropyl-modified precursors of chondroitin sulfate (CS) tetrasaccharides have been synthesized, which, after facile conversion to final CS structures, may be conjugated with alkyne-modified target compounds by a one-pot "click"-ligation. RP HPLC was used for the monitoring of the key reaction steps (protecting group manipulation and sulfation) and purification of the CS precursors (as partially protected form, bearing the O-Lev, O-benzoyl, and N-trichloroacetyl groups and methyl esters). Subsequent treatments with aqueous NaOH, concentrated ammonia, and acetic anhydride (i.e., global deprotection and acetylation of the galactosamine units) converted the precursors to final CS structures. The azidopropyl group was exposed to a strain promoted azide alkyne cydoacklition (SPAAC) with a dibenzyl-cyclooctyne-modified carboxyrhodamine dye to give labeled CSs. Conjugation with a 5'-cyclooctyne-modified oligonucleotide was additionally carried out to show the applicability of the precursors for the synthesis of biomolecular hybrids.