Kifunensine

A practical synthesis of kifunensine analogues as inhibitors of endoplasmic reticulum alpha-mannosidase I.[Pubmed:16292820]

J Org Chem. 2005 Nov 25;70(24):9892-904.

[reaction: see text] A practical synthesis of the potent class I alpha-mannosidase inhibitor Kifunensine (1) beginning from the inexpensive and readily available starting material L-ascorbic acid (15) is described. The protected amino-alcohol ((2R,3R,4R,5R)-5-amino-2,3:4,6-diisopropylidenedioxyhexanol, 11) served as a key intermediate from which several N-1 substituted Kifunensine analogues (including N-methyl, N-cyclohexyl, and N-bis(hydroxymethyl)methyl) and 2-desoxaKifunensine analogues (including N-H and N-methyl) were prepared and screened for inhibition of human endoplasmic reticulum alpha-mannosidase I (ER Man I) and mouse Golgi alpha-mannosidase IA (Golgi Man IA). In addition, several pseudodisaccharide Kifunensine analogues in which a mannose residue was tethered to N-1 of Kifunensine via a two-, three-, or four-carbon linker and an affinity-bound Kifunensine analogue were also prepared and evaluated for biological activity. While the synthesized N-1 kifunesine analogues were found to be less potent inhibitors of Class I alpha-mannosidases than kifuensine itself, the bis(hydroxymethyl)methylKifunensine analogue 6 was shown to selectively inhibit ER Man I over Golgi Man IA.

Synthesis of kifunensine thioanalogs and their inhibitory activities against HIV-RT and alpha-mannosidase.[Pubmed:23159373]

Carbohydr Res. 2013 Jan 10;365:1-8.

An efficient and practical synthesis of Kifunensine thioanalogs 1a-c was reported. The bicyclic azasugars fused thiazolidin-4-one 4a-c as key intermediates were first synthesized in good yields of 74-80% via one-pot tandem Staudinger/aza-Wittig/cyclization by using the pivotal azidosugars 3a and 3b derived from D-mannose. Followed by double Pummerer rearrangements and deprotection, the target thioKifunensine 1a and its epimers 1b and 1c were obtained in good yields. Compounds 1a-c were preliminary evaluated for their HIV-RT and alpha-mannosidase (Jack bean) inhibitory activities. The results showed that such compounds exhibited significant anti-HIV-RT inhibitory activity but poor inhibitory against alpha-mannosidase. To gain further insight into the inhibitory mechanism of compounds 1a-c, the analog compounds 9a-c were also prepared after deprotection from 4a-c, respectively. Activity comparison between compounds 1a-c and 9a-c suggests that the better activities of 1a-c than those of the 9a-c is possibly due to the additional carbonyl at thiazolidine-4-one ring in fused bicyclic azasugars.

Use of the alpha-mannosidase I inhibitor kifunensine allows the crystallization of apo CTLA-4 homodimer produced in long-term cultures of Chinese hamster ovary cells.[Pubmed:21795794]

Acta Crystallogr Sect F Struct Biol Cryst Commun. 2011 Jul 1;67(Pt 7):785-9.

Glycoproteins present problems for structural analysis since they often have to be glycosylated in order to fold correctly and because their chemical and conformational heterogeneity generally inhibits crystallization. It is shown that the alpha-mannosidase I inhibitor Kifunensine, which has previously been used for the purpose of glycoprotein crystallization in short-term (3-5 d) cultures, is apparently stable enough to be used to produce highly endoglycosidase H-sensitive glycoprotein in long-term (3-4 week) cultures of stably transfected Chinese hamster ovary (CHO) cells. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry-based analysis of the extracellular region of the cytotoxic T-lymphocyte antigen 4 (CTLA-4; CD152) homodimer expressed in long-term CHO cell cultures in the presence of Kifunensine revealed that the inhibitor restricted CTLA-4 glycan processing to Man9GlcNAc2 and Man5GlcNAc2 structures. Complex-type glycans were undetectable, suggesting that the inhibitor was active for the entire duration of the cultures. Endoglycosidase treatment of the homodimer yielded protein that readily formed orthorhombic crystals with unit-cell parameters a=43.9, b=51.5, c=102.9 A and space group P2(1)2(1)2(1) that diffracted to Bragg spacings of 1.8 A. The results indicate that Kifunensine will be effective in most, if not all, transient and long-term mammalian cell-based expression systems.

A combined STD-NMR/molecular modeling protocol for predicting the binding modes of the glycosidase inhibitors kifunensine and salacinol to Golgi alpha-mannosidase II.[Pubmed:15865418]

Biochemistry. 2005 May 10;44(18):6729-37.

A combined STD-NMR/molecular modeling protocol to probe the binding modes of the glycosidase inhibitors Kifunensine and salacinol to Drosophila melanogaster Golgi alpha-mannosidase II (dGMII) was tested. Saturation-transfer difference (STD) NMR experiments were carried out for the complexes of dGMII with these two inhibitors. The program AutoDock 3.0 was then used to optimize the interactions of the inhibitors with the residues in the active site of dGMII. Theoretical STD effects of the ligand protons in the complexes were calculated for the different binding modes with the recently developed CORCEMA-ST protocol. Comparison of experimental and theoretical effects then permitted selection of the likely binding modes of the ligands. The more rigid Kifunensine was used initially to test the protocol. Excellent correlation between experimental and theoretical data was obtained for one of the binding modes that also corresponded to that observed in the crystal structure of the complex. The protocol was then extended to the more flexible salacinol. For the selected binding mode, good correlation of experimental and theoretical data for the five-membered ring was obtained; however, poor correlation for protons on the acyclic chain was obtained, suggesting flexibility in this portion of the molecule. Comparison of the selected binding mode with that from a crystal structure of salacinol with dGMII showed excellent superimposition of the five-membered ring but another orientation of the acyclic chain. The results suggest that reliable structural binding modes of a ligand to protein in aqueous solution can be provided with the combined use of STD-NMR spectroscopy, molecular modeling, and CORCEMA-ST calculations, although highly flexible portions of the ligand may be poorly defined.