Derivatives of 1-deoxy-galactonojirimicina and their use in treating related enfermadades lysosomal storage enhancing lysosomal alpha-galactosidase.

Use of an effective amount of a compound of the following formula: ** (See formula) ** wherein R1 represents H, CH3, CH2CH3 or R 2 and R 3 independently represent H, OH, a 1-6 carbon , hydroxyalkyl, alkoxy, or a simple sugar; and R4 and R5 independently represent H or OH; or ** (See formula) ** wherein for calystegine A 3: R 1 = H, R 2 = OH, R 3 = H, R 4 = H; for calystegine B2: R1 = H, R2 = OH, R3 = H, R4 = OH; for calystegine B 3: R 1 = H, R 2 = H, R 3 = OH, R 4 = OH; and N-methyl-calystegine: R1 = CH3, R2 = OH, R3 = H, R4 = OH; in the manufacture of a medicament for treating a disease glycosphingolipid lysosomal storage, wherein the compound is an inhibitor of an enzyme that is deficient in the disease glycosphingolipid lysosomal storage.