ez-ADiCon: A novel glyco-remodeling based strategy that enables preparation of homogenous antibody-drug conjugates via one-step enzymatic transglycosylation with payload-preloaded bi-antennary glycan complexes.

The conserved N-linked glycan at the Fc domain of recombinant monoclonal antibodies is an attractive target for site-specific payload conjugation for preparation of homogenous antibody-drug conjugates (ADCs). Here, we report a novel ADC constructing strategy, named "ez-ADiCon", that is achieved by one-step enzymatic transglycosylation of a payload-preloaded bi-antennary glycan oxazoline onto a deglycosylated antibody. In this method, a mixture of different glycoforms of the Fc-glycan is replaced with a pre-defined payload-linked glycan. Since two payloads are linked on each donor glycan substrate, efficient conjugation results in a highly homogenous ADC with mostly-four drug molecules per antibody, facilitating hydrophobic interaction chromatography analysis and purification. We validated this conjugation strategy using Monomethyl auristatin E (MMAE) and an anti-Human epidermal growth factor receptor 2 (anti-Her2) antibody as the model ADC components and demonstrated its target-specific in vitro cytotoxicity. Our novel conjugation strategy, ez-ADiCon, provides a new approach for the preparation of next generation ADCs.

Preferential capture of EpCAM-expressing extracellular vesicles on solid surfaces coated with an aptamer-conjugated zwitterionic polymer.

Extracellular vesicles (EVs) collectively represent small vesicles that are secreted from cells and carry biomolecules (e.g., miRNA, lncRNA, mRNA, proteins, lipids, metabolites, etc.) that originate in those cells. Body fluids, such as blood and saliva, include large numbers of EVs, making them potentially a rich source of diagnostic information. However, these EVs are mixtures of vesicles released from diseased tissues as well as from normal cells. This heterogeneous nature therefore blurs the clinical information obtainable from EV-based diagnosis. Here, we synthesized an EpCAM-affinity coating agent, which consists of a peptide aptamer for EpCAM and a zwitterionic MPC polymer, and have shown that this conjugate endowed the surfaces of inorganic materials with the preferential affinity to EpCAM-expressing EVs. This coating agent, designated as EpiVeta, could be useful as a coating for various diagnostic devices to allow concentration of cancer-related EVs from heterogeneous EV mixtures.

Enantioselective Total Synthesis of RQN-18690A (18-Deoxyherboxidiene).

The first total synthesis of RQN-18690A (18-deoxyherboxidiene) and the determination of its absolute stereochemical configuration are described. The synthesis features an organocatalytic aldol reaction for the first step, 1,4- and 1,2- dual reductions of α,ß-unsaturated δ-lactone followed by a domino reaction in a one-pot operation, and diastereoselective epoxidation with kinetic resolution.

Direct asymmetric alpha-amination of cyclic ketones catalyzed by siloxyproline.

trans-tert-Butyldimethylsiloxy-L-proline displays greater catalytic activity and affords higher enantioselectivity than the parent proline in the alpha-amination reaction of carbonyl compounds with azodicarboxylate. A quantum mechanical calculation reveals the structure of the transition state. In the presence of a catalytic amount of siloxyproline and water (3-9 equiv), alpha-amino carbonyl derivatives, which are important synthetic intermediates, are obtained in good yield and with excellent enantioselectivity.

Direct proline-catalyzed asymmetric alpha-aminoxylation of aldehydes and ketones.

The direct proline-catalyzed asymmetric alpha-aminoxylation of aldehydes and ketones has been developed using nitrosobenzene as an oxygen source, affording alpha-anilinoxy-aldehydes and -ketones with excellent enantioselectivity. Reaction conditions have been optimized, and low temperature (-20 degrees C) was found to be a key for the successful alpha-aminoxylation of aldehydes, while slow addition of nitrosobenzene is essential for that of ketones. The scope of the reaction is presented.