Preparations of the highly-ordered monoantennary, homofunctional diantennary, and heterofunctional diantennary neoglycopolymers of a-D-mannose and β-D-glucose residues were achieved via ring-opening metathesis polymerization. Isothermal titration calorimetry measurements of these synthetic neoglycopolymers with Concanavalin A, revealed that hetero-functional diantennary architectures bearing both a-mannose and non-binding β-glucose units, poly(Man-Glc), binds to Concanavalin A (Ka = 16.1 × 106 M−1) comparably to homofunctional diantennary neoglycopolymer (Ka = 30 × 106 M−1) bearing only a-mannose unit, poly(Man-Man). In addition, poly(Man-Glc) neoglycopolymer shows a nearly five-fold increasing in binding affinity compared to monoantennary neoglycopolymer, poly(Man). Although the exact mechanism for the high binding affinity of poly(Man-Glc) to Con A is unclear, we hypothesize that the α-mannose bound to Con A might facilitate interaction of β-glucose with the extended binding site of Con A due to the close proximity of β-glucose to α-mannose residues in the designed polymerizable scaffold.
Surface reactions were performed on polypropylene (PP) surfaces to retard the simultaneous growth of Staphylococcus aureus (S. aureus) and Pseudomonas putida (P. putida) bacteria. Microwave plasma reactions in the presence of maleic anhydride (MA) resulted in the formation of acid groups on the surface of PP. Such surfaces were further modified by conducting two parallel reactions: (1) poly(ethylene glycol) (PEG) was attached to COOH groups of the PP surface, followed by penicillin V (PEN) reactions to target S. aureus destruction and (2) diglycidyl PEG was attached, followed by gentamicin (GEN) reactions, to create antimicrobial surfaces targeted at P. putida . Simultaneous gram "+" and gram "-" resistance was obtained by varying the PEN/GEN ratios on such modified PP surfaces, thus providing the controllable degree of gram "+" and gram "-" antimicrobial strength. While spectroscopic analyses revealed chemical attachments of PEN and GEN, the effectiveness against proliferation of S. aureus (Gram +) and P. putida (Gram -) bacteria was determined using liquid culture tests. These studies show for the first time the formation of tunable antimicrobial polypropylene surfaces with controllable strength.
The highly α-selective and scalable synthesis of the Fmoc-protected GalNAc-threonine amino acid and TN antigen in gram scale (0.5 – 1 gram), is described. The challenging 1,2-cis-2-amino glycosidic bond is addressed through a coupling of threonine units with C(2)-N-ortho-(trifluoromethyl)benzylidenamino trihaloacetimidate donors mediated by Ni(4-F-PhCN)4(OTf)2. The desired 1,2-cis-2-amino glycoside was obtained in 66% (3.77 g) with α-only selectivity and subsequently transformed into the Fmoc-protected GalNAc-threonine and TN antigen. This operationally simple procedure no longer requires utilization of the commonly used C(2)-azido donors and overcomes many of the limitations associated with the synthesis of 1,2-cis linkage.
Formal synthesis of mycothiol has been developed via nickel-catalyzed α-glycosylation of the C(1)-hydroxyl group of D-myo-inositols with C(2)-N-substituted benzylideneamino N-phenyl trifluoroacetimidate donors. The pseudo-oligosaccharides were obtained in good yield and with excellent α-selectivity. Removal of the C(2)-N-2-trifluoromethylphenyl-benzylidene group under mild conditions provides a pseudo-disaccharide, completing the formal synthesis of mycothiol.
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