Preparation, biochemical characterization and biological properties of radiolabelled N-alkylated deoxynojirimycins.
We have reductively alkylated deoxynojirimycin imino sugars using sodium cyanoborohydride to provide an efficient means of generating a series of N-alkylated compounds containing 4-18 carbon side chains. The yields were greater than 90% using a variety of aldehydes of different chain lengths, and after purification were >95% pure using (1)H-NMR. Radiolabelled compounds were prepared using sodium cyanoborotriti-ide to selectively label the first carbon atom in the alkyl chain and used in protein-binding and cell- and tissue-uptake experiments. Protein binding was chain-length-dependent with compounds of intermediate chain length (C(9)-C(12)), demonstrating an equal distribution between the aqueous and protein-bound phase. The extent of cell uptake also increased proportionally with increased chain length in a time-dependent manner. When administered to mice, the longer alkyl-chain compounds showed reduced absorption from the intestine and a marked deposition of compound in the liver and brain, suggesting that the more hydrophobic compounds were poorly cleared by the major tissues. In tissue-culture cells compounds with 8 or fewer carbon atoms were non-toxic and had CC(50) (the concentration at which the number of cells or cell proliferation is reduced by 50%) values greater than 1 mM. Compounds with chain lengths above C(8) showed a chain-length-dependent increase in cytotoxicity. N-alkylated deoxynojirimycins (C(4)-C(18)) were evaluated for their inhibitory effects on ceramide-specific glucosyltransferase and glycoprotein-processing alpha-glucosidase. Increasing the alkyl chain length had little effect on alpha-glucosidase activity, but inhibition of ceramide-specific glucosyltransferase increased 10-fold when C(4) and C(9)-C(18) compounds were compared. Overall these data provide further definition of the molecular features of alkylated imino sugars that influence tissue selectivity and efficacy for cellular enzyme inhibition.
Mellor
Howard R
HR
Glycobiology Institute, Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, U.K.
Nolan
James
J
Pickering
Lea
L
Wormald
Mark R
MR
Platt
Frances M
FM
Dwek
Raymond A
RA
Fleet
George W J
GW
Butters
Terry D
TD
D017485:1-Deoxynojirimycin / Q000737:chemistry / Q000494:pharmacology*; D000478:Alkylation; D000818:Animals; D001921:Brain / Q000378:metabolism; D002417:Cattle; D002455:Cell Division; D002460:Cell Line; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000494:pharmacology*; D006017:Glycolipids / Q000378:metabolism; D007700:Kinetics; D008099:Liver / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D051379:Mice; D008956:Models, Chemical; D013997:Time Factors; D014018:Tissue Distribution
D004791:Enzyme Inhibitors; D006017:Glycolipids; D017485:1-Deoxynojirimycin