Correlation between thermostability and stability of glycosidases in ionic liquid

The activity and stability of a β-glycosidase (Thermus thermophilus) and two α-galactosidases (Thermotoga maritima and Bacillus stearothermophilus) were studied in different hydrophilic ionic liquid (IL)/water ratios. For the ILs used, the glycosidases showed the best stability and activity in 1,3-dimethylimidazolium methyl sulfate [MMIM][MeSO(4)] and 1,2,3-trimethylimidazolium methyl sulfate [TMIM][MeSO(4)]. A close correlation was observed between the thermostability of the enzymes and their stability in IL media. At high IL concentration (80%), a time-dependent irreversible denaturing effect was observed on glycosidases while, at lower concentration (<30%), a reversible inactivation affecting mainly the k (cat) was obtained. The results demonstrate that highly thermostable glycosidases are more suitable for biocatalytic reactions in water-miscible ILs.

Discovery of a β-glucosidase inhibitor from a chemically engineered extract prepared through sulfonylation

A semisynthetic β-glucosidase inhibitor was identified from a chemically engineered extract prepared by reaction with benzenesulfonyl chloride. The structure includes a natural histamine portion and a benzenesulfonyl portion introduced during the diversification step.

Imino sugars and glycosyl hydrolases: historical context, current aspects, emerging trends

Forty years of discoveries and research on imino sugars, which are carbohydrate analogues having a basic nitrogen atom instead of oxygen in the sugar ring and, acting as potent glycosidase inhibitors, have made considerable impact on our contemporary understanding of glycosidases. Imino sugars have helped to elucidate the catalytic machinery of glycosidases and have refined our methods and concepts of utilizing them. A number of new aspects have emerged for employing imino sugars as pharmaceutical compounds, based on their profound effects on metabolic activities in which glycosidases are involved. From the digestion of starch to the fight against viral infections, from research into malignant diseases to potential improvements in hereditary storage disorders, glycosidase action and inhibition are essential issues. This account aims at combining general developments with a focus on some niches where imino sugars have become useful tools for glycochemistry and glycobiology.

Synthesis and evaluation of D-gluco-pyranocyclopropyl amines as potential glucosidase inhibitors

In the recent past sugar-derived cyclopropylamines were proposed as structurally new glycosidase inhibitors. In this Letter we report our efforts in the synthesis of a set of alpha-glucose configured oxabicyclo[4.1.0] heptanes, based on this hypothesis, bearing an amine substituent on the propyl ring and reveal that their inhibitory potential towards a range of mammalian glucosidases is modest.

Structure based development of phenylimidazole-derived inhibitors of indoleamine 2,3-dioxygenase

Indoleamine 2,3-dioxygenase (IDO) is emerging as an important new therapeutic target for the treatment of cancer, chronic viral infections, and other diseases characterized by pathological immune suppression. With the goal of developing more potent IDO inhibitors, a systematic study of 4-phenylimidazole (4-PI) derivatives was undertaken. Computational docking experiments guided design and synthesis efforts with analogues of 4-PI. In particular, three interactions of 4-PI analogues with IDO were studied: the active site entrance, the interior of the active site, and the heme iron binding. The three most potent inhibitors (1, 17, and 18) appear to exploit interactions with C129 and S167 in the interior of the active site. All three inhibitors are approximately 10-fold more potent than 4-PI. The study represents the first example of enzyme inhibitor development with the recently reported crystal structure of IDO and offers important lessons in the search for more potent inhibitors.

Improved chemical syntheses of 5,6-dihydro-5-fluorouracil

5,6-dihydro-5-fluorouracil (5-DHFU) is a metabolite of the chemotherapy drug 5-fluorouracil (5-FU) of importance for biological studies. 5-DHFU has been prepared by enzymatic reduction of 5-FU and in very low yield by hydrogenation of 5-FU; however, a practical chemical synthesis is not available. Facile racemic syntheses of 5-DHFU from 5-FU or uracil, using p-methoxybenzyl protecting groups followed by L-Selectride reduction, are reported.