Synthesis for (68)Ga-labeled 1,4,7-triazacyclononane-1,4,7-triacetic acid (NOTA)-chelated oligonucleotide hyaluronan (HA) tetra- and hexasaccharide conjugates is described. A solid-supported technique is used to introduce NOTA-chelator into the 3'-terminus of oligonucleotides and a copper-free strain promoted azide alkyne cycloaddition (SPAAC) to HA/oligonucleotide conjugation. Protecting group manipulation, required for the HA-moieties, is carried out after the SPAAC-conjugation. Positron emission tomography (PET) is used (1) in the whole-body distribution kinetic studies of the conjugates in healthy rats and (2) to show the potential of hyaluronan-induced targeting of oligonucleotides into the infarcted area of rats with myocardial infarction.
Nucleic Acid Therapeutics (NATs), including siRNAs and AntiSense Oligonucleotides (ASOs), have great potential to drug the undruggable genome. Targeting siRNAs and ASOs to specific cell types of interest has driven dramatic improvement in efficacy and reduction in toxicity. Indeed, conjugation of tris-GalNAc to siRNAs and ASOs has shown clinical efficacy in targeting diseases driven by liver hepatocytes. However, targeting non-hepatic diseases with oligonucleotide therapeutics has remained problematic for several reasons, including targeting specific cell types and endosomal escape. Monoclonal antibody (mAb) targeting of siRNAs and ASOs has the potential to deliver these drugs to a variety of specific cell and tissue types. However, most conjugation strategies rely on random chemical conjugation through lysine or cysteine residues resulting in conjugate heterogeneity and a distribution of Drug:Antibody Ratios (DAR). To produce homogeneous DAR-2 conjugates with two siRNAs per mAb, we developed a novel two-step conjugation procedure involving microbial transglutaminase (MTGase) tagging of the antibody C-terminus with an azide-functionalized linker peptide that can be subsequently conjugated to dibenzylcyclooctyne (DBCO) bearing oligonucleotides through azide-alkyne cycloaddition. Antibody-siRNA (and ASO) conjugates (ARCs) produced using this strategy are soluble, chemically defined targeted oligonucleotide therapeutics that have the potential to greatly increase the number of targetable cell types.
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
cycloaddition (SPAAC) with a dibenzylcyclooctyne-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.
Enantioselective synthesis of deoxy analogues of pyranonaphthoquinone antibiotics (+)-nanomycin A methyl ester, (+)-eleutherin, (+)-allo-eleutherin, and (+)-thysanone was achieved in good overall yield with high enantio-and diastereoselectivity from the common intermediate (R)-3-(2,5-dimethoxyphenyl)propane-1,2-diol. The intramolecular oxaPictet-Spengler cyclization of 6-aryl-1,3-dioxolone was de-
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