Synthesis of Isofagomine Derivatives as New Fluorescence pH Indicators/Glycosidase Inhibitors

Abstract

Inhibitor protonation of azasugars of the isofagomine type when bound to enzyme can be investigated using photon induced electron transfer (PET) quenching of an attached fluorophore. For this purpose, Isofagomine, iso‐d‐galacto‐fagomine, and iso‐l‐gulo‐fagomine were converted to N‐(10‐chloroanthracenenyl‐9‐alkyl) derivatives where the alkyl group contained one, two, or three methylene groups. The new derivatives displayed pH dependent fluorescence; as the ammonium forms they were fluorescent, while 90–99 % of the fluorescence was quenched in the amine forms. The 3 isofagomine derivatives were competitive inhibitors of T. Maritima Ι‐glucosidase with Ki values from 0.37–4.6ΤM. Similarly, the iso‐d‐galacto‐fagomines inhibited A. Niger Ι‐galactosidase with Ki values from 63–2000 nm. When bound to the enzymes the inhibitors displayed between 1–15 % fluorescence.

A remarkable change in inhibition potency and selectivity of isofagomine by simple N-modification

“…Accordingly, dedicated derivatizations (Fig. 1) of either the ring nitrogen (i.e., compound 4-9) [4][5][6][7][8][9][10][11][12][13][14], selected alcohols (i.e., compound 10 and 11) [15][16][17][18], or the carbon backbone (i.e., compound 12 and 13) [14,19], as well as advanced combinations thereof (i.e., 14) [20], provided a broad set of innovative inhibitors of respective glycosidases. In consequence, appropriate structures of this compound class have been elaborated upon their biological activity against selected human glycosidases related to lysosomal storage diseases [3,21].…”

Synthesis and Evaluation of Novel Iminosugars Prepared from Natural Amino Acids

“…The possibility of variations in the substitution pattern of the cyclopropane allows different configurations that could direct their selectivity to different glycosidases. Although the development of synthetic routes to iminosugars has received much attention in the synthetic community [ 14 , 15 ], the preferred chiral pools are carbohydrates, which are transformed using reductive aminations [ 16 , 17 ], or other transformation strategies [ 18 ]. In our case, we developed synthetic approaches from natural amino acids, which have less precedents [ 19 , 20 ].…”