Strategies in Synthesis of Heparin/Heparan Sulfate Oligosaccharides: 2000-Present

Stereoselective Glycosylation for 1,2-cis-Aminoglycoside Assembly by Cooperative Atom Transfer Catalysis

We report here a new catalytic method for exclusively 1,2-cis-α-selective glycosylation that assembles a wide variety of 1,2-cis-aminoglycosidic linkages in complex glycans and glycoconjugates. Mechanistic studies revealed a unique glycosylation mechanism in which the iron catalyst activates a glycosyl acceptor and an oxidant when it facilitates the cooperative atom transfer of both moieties to a glycosyl donor in an exclusively cis-selective manner. This catalytic approach is effective for a broad range of glycosyl donors and acceptors, and it can be operated in a reiterative fashion and scaled up to the multigram scale.

Quality control, safety assessment and preparation approaches of low molecular weight heparin

Low Molecular Weight Heparins (LMWHs) are well-established for use in the prevention and treatment of thrombotic diseases, and as a substitute for unfractionated heparin (UFH) due to their predictable pharmacokinetics and subcutaneous bioavailability. LMWHs are produced by various depolymerization methods from UFH, resulting in heterogeneous compounds with similar biochemical and pharmacological properties. However, the delicate supply chain of UFH and potential contamination from animal sources require new manufacturing approaches for LMWHs. Various LMWH preparation methods are emerging, such as chemical synthesis, enzymatic or chemical depolymerization and chemoenzymatic synthesis. To establish the sameness of active ingredients in both innovator and generic LMWH products, the Food and Drug Administration has implemented a stringent scientific method of equivalence based on physicochemical properties, heparin source material and depolymerization techniques, disaccharide composition and oligosaccharide mapping, biological and biochemical properties, and in vivo pharmacodynamic profiles. In this review, we discuss currently available LMWHs, potential manufacturing methods, and recent progress for manufacturing quality control of these LMWHs.

The mutation of Japanese encephalitis virus envelope protein residue 389 attenuates viral neuroinvasiveness

The envelope (E) protein of the Japanese encephalitis virus (JEV) is a key protein for virus infection and adsorption of host cells, which determines the virulence of the virus and regulates the intensity of inflammatory response. The mutation of multiple aa residues in the E protein plays a critical role in the attenuated strain of JEV. This study demonstrated that the Asp to Gly, Ser, and His mutation of the E389 site, respectively, the replication ability of the viruses in cells was significantly reduced, and the viral neuroinvasiveness was attenuated to different degrees. Among them, the mutation at E389 site enhanced the E protein flexibility contributed to the attenuation of neuroinvasiveness. In contrast, less flexibility of E protein enhanced the neuroinvasiveness of the strain. Our results indicate that the mechanism of attenuation of E389 aa mutation attenuates neuroinvasiveness is related to increased flexibility of the E protein. In addition, the increased flexibility of E protein enhanced the viral sensitivity to heparin inhibition in vitro, which may lead to a decrease in the viral load entering brain. These results suggest that E389 residue is a potential site affecting JEV virulence, and the flexibility of the E protein of aa at this site plays an important role in the determination of neuroinvasiveness.

Synthesis of Anticoagulant Pentasaccharide Fondaparinux via 3,5-Dimethyl-4-(2'-phenylethynylphenyl)phenyl Glycosides

Here, we disclosed a convenient procedure for the preparation of EPP [3,5-dimethyl-4-(2'-phenylethynylphenyl)phenyl] glycosides and their application to an effective synthesis of fondaparinux, the clinically approved anticoagulant heparin pentasaccharide. The use of EPP glycosides in the one-pot orthogonal glycosylation for the synthesis of heparin-like tetrasaccharides has also been achieved.

Design and Synthesis of Neutralizable Fondaparinux

Fondaparinux, a clinically approved anticoagulant pentasaccharide for the treatment of thrombotic diseases, displays better efficacy and biosafety than other heparin-based anticoagulant drugs. However, there is no suitable antidote available for fondaparinux to efficiently manage its potential bleeding risks, thereby precluding its widespread use. Herein, we describe a convergent and stereocontrolled approach to efficiently synthesize an aminopentyl-functionalized pentasaccharide, which is further used to prepare fondaparinux-based biotin conjugates and clusters. Biological activity evaluation demonstrates that the anticoagulant activity of the fondaparinux-based biotin conjugate and trimer is, respectively, neutralized by avidin and protamine as effective antidotes. This work suggests that our synthetic biotin conjugate and trimer have potential for the development of neutralizable and safe anticoagulant drugs.