Gerrit Jan Koomen

Generation of Specific Deoxynojirimycin-type Inhibitors of the Non-lysosomal Glucosylceramidase

The existence of a non-lysosomal glucosylceramidase in human cells has been documented (van Weely, S., Brandsma, M., Strijland, A., Tager, J. M., and Aerts, J. M. F. G. (1993) Biochim. Biophys. Acta 1181, 55–62). Hypothetically, the activity of this enzyme, which is localized near the cell surface, may influence ceramide-mediated signaling processes. To obtain insight in the physiological importance of the non-lysosomal glucosylceramidase, the availability of specific inhibitors would be helpful. Here we report on the generation of hydrophobic deoxynojirimycin (DNM) derivatives that potently inhibit the enzyme. The inhibitors were designed on the basis of the known features of the non-lysosomal glucosylceramidase and consist of a DNM moiety, an N-alkyl spacer, and a large hydrophobic group that promotes insertion in membranes. In particular,N-(5-adamantane-1-yl-methoxy)pentyl)-DNM is a very powerful inhibitor of the non-lysosomal glucosylceramidase at nanomolar concentrations. At such concentrations, the lysosomal glucocerebrosidase and α-glucosidase, the glucosylceramide synthase, and the N-linked glycan-trimming α-glucosidases of the endoplasmic reticulum are not affected.

Unconventional nucleotide analogues. Part X. Synthesis of N-substituted 3-(adenin-9-yl)pyrrolidin-2-ones

3-(Adenin-9-yl)-N-2-hydroxyethylpyrrolidin-2-one (1) was synthesized by constructing the purine base on the amino-group of 3-amino-N-2-hydroxyethylpyrrolidin-2-one (3), itself obtained from 2-dibenzylaminobutyro-lactone by aminolysis, followed by chlorination of the product and recyclization. Attempts to obtain compound (3) from acylated 2-aminobutyrolactones (4a and b) led to side reactions, the mechanisms of which are discussed. 3-(6-Chloropurin-9-yl)-N-2-hydroxyethylpyrrolidin-2-one (18b) was converted into the AMP analogue (2) by a phosphorylation–amination–debenzylation sequence, lodination of compound (1), followed by dehydrohalogen-ation of the product led to the N-vinyl derivative (21 ), a monomer for a poly-A model.

Unconventional nucleotide analogues. Part IX. N-substituted 3-( pyrimidin-1-yl)pyrrolidin-2-ones

Hubert–Johnson reaction of the 2,4-diethoxypyrimidines (2a and b) with 2-bromobutyrolactone (3), followed by hydrolysis of the coupling products (4a and b), gave the pyrimidin-1-yl lactones (5a and b). 2-(1,2,3,4-Tetra-hydro-2,4-dioxopyrimidin-1 -yl)butyrolactone (5a) was converted into the N-vinyipyrrolidin-2-one analogue (11)via a five-step reaction sequence [(5a)→(7a)→(7b)→(8)→(10c)→(11)]. Polymerisation of the product (11) yielded material (12)(mol. wt. 80,000) which, in aqueous solution, exhibited a pronounced (25%) hypochromicity effect at 263 nm.