Highly Reactive Glycosylation with 1-(Methylthio)thiocarbonyl Glycosyl Donors under Acidic to Neutral Reaction Conditions.

In this study, we have successfully developed a glycosylation method using 1--(methylthio)thiocarbonyl-glycoses as donors. Such xanthate donors are easily accessible and shelf-stable. The glycosylation reaction could be promoted by cations (acidic to neutral conditions) under mild conditions, exhibiting a reactivity intermediate between that with glycosyl trichloroacetimidate as the donor and that with thioglycoside as the donor.

Regioselective Glycosylation of Mannoside and Galactoside Acceptors Containing 2,4-OH Achieved by Altering Protecting Groups at the 1,3,6-Positions.

In this study, we systematically investigated the regioselective glycosylation of 2,4-OH mannoside and galactoside acceptors since regioselective protection of their 3- and 6-OHs is readily achieved. By altering the protecting groups at 1-, 3-, and 6-positions of such acceptors, we finally screened -methoxyphenyl 3-OBn, 6-OTBDPS, α-mannoside, and β-galactoside acceptors whose 2-OHs exhibited excellent selectivity for glycosylation with various glycosyl donors, leading to 1,2-linked products in 70-82% yields. By utilizing such acceptors, a series of 2,4-linked trisaccharide products (53-65% yields over two steps) have been highly efficiently synthesized without the need for complex protection/deprotection operations at the 2- and 4-positions of these acceptors.

Design, Synthesis, and Biological Evaluation of Thioglucoside Analogues of Gliflozin as Potent New Gliflozin Drugs.

In this study, we have investigated the potential of two classes of thioglucoside analogues of gliflozins as antidiabetic drugs, one with substitutions of S-atoms in meta-positions (similar to -glucoside SGLT2 inhibitors, TAGs , , and ) and the other with substitutions of S-atoms in ortho-positions (similar to -glucoside SGLT2 inhibitors, TAGs , , , and ). These TAGs were confirmed to show good stability against β-glucosidase and to have no acute toxicity to cultured cells. Most importantly, TAGs , , , and all showed high inhibitory activity against SGLT2 (IC: 2.

Visible-Light-Promoted Desulfurization to Synthesize Deoxyglycosides.

In this study, we have successfully applied a visible-light-promoted desulfurization method to the synthesis of deoxysugars, especially 1-deoxyglycose, 2,4-deoxyglycosides, and 2-deoxyglycosides with exclusive α-configuration. Compared to the reported desulfurization under UV light (500 W mercury lamp), this desulfurization under visible light (20 W blue LED) is easy to operate since it does not require a dedicated photochemical reactor, occurs under very mild conditions, and is able to avoid many of the side reactions that often occur during the UV-induced desulfurization.

SnCl Promoted Efficient Cleavage of Acetal/Ketal Groups with the Assistance of Water in CHCl.

Acetalization and deacetalation are a pair of routine manipulations to protect and deprotect the 4- and 6-hydroxyl groups of glycosides in the synthesis of glycosyl building blocks. In this study, we found that treatment of SnCl with various carbohydrates containing acetal/ketal groups with the assistance of water in CHCl led to deacetalization/deketalization products in almost quantitative yields. In addition, for substrates containing both acetal/ketal and -methoxylbenzyl groups, we also found that the -methoxylbenzyl group was selectively cleaved by the use of a catalytic amount of SnCl, while the acetal/ketal groups remained.

Efficient Synthesis of 2-OH Thioglycosides from Glycals Based on the Reduction of Aryl Disulfides by NaBH.

An improved method to efficiently synthesize 2-OH thioaryl glycosides starting from corresponding per-protected glycals was developed, where 1,2-anhydro sugars were prepared by the oxidation of glycals with oxone, followed by reaction of crude crystalline 1,2-anhydro sugars with NaBH and aryl disulfides. This method has been further used in a one-pot reaction to synthesize glycosyl donors having both "armed" and "NGP (neighboring group participation)" effects.

Concise Synthesis of 1-Thioalkyl Glycoside Donors by Reaction of Per-O-acetylated Sugars with Sodium Alkanethiolates under Solvent-Free Conditions.

A relatively green method for synthesizing 1-thioalkyl glycosides has been developed, where sodium alkanethiolates were used to react with per-O-acetylated sugars instead of odorous alkyl mercaptans in the presence of BF·EtO without the use of solvents under mild conditions. Furthermore, we found that 1,2--β-thioglycosides can be converted into corresponding 1,2--α-thioglycosides in the presence of trifluoromethanesulfonic acid in nonpolar solvents under mild conditions. This provides a simple and efficient new approach for synthesizing challenging 1,2--α-thioglycosides.

Characterization of Full-Length Genomes of Hepatitis B Virus Quasispecies in Sera of Patients at Different Phases of Infection.

Hepatitis B virus (HBV) infection results in different clinical presentation due to different levels of immune response. Our study aimed to characterize HBV full-length genome quasispecies (QS) in patients with different phases of infection to better understand its pathogenesis. Forty treatment-naive HBV-infected patients were enrolled, including 10 cases of acute hepatitis B (AHB), 9 cases of immunotolerant (IT) HBV carriers, 11 cases of chronic hepatitis B (CHB), and 10 cases of acute-on-chronic liver failure (ACLF).

Update of TTD: Therapeutic Target Database.

Increasing numbers of proteins, nucleic acids and other molecular entities have been explored as therapeutic targets, hundreds of which are targets of approved and clinical trial drugs. Knowledge of these targets and corresponding drugs, particularly those in clinical uses and trials, is highly useful for facilitating drug discovery. Therapeutic Target Database (TTD) has been developed to provide information about therapeutic targets and corresponding drugs.