Isolation from Stevia rebaudiana of DMDP acetic acid, a novel iminosugar amino acid: synthesis and glycosidase inhibition profile of glycine and ß-alanine pyrrolidine amino acids.

DMDP acetic acid [N-carboxymethyl-2,5-dideoxy-2,5-imino-D-mannitol] 5 from Stevia rebaudiana is the first isolated natural amino acid derived from iminosugars bearing an N-alkyl acid side chain; it is clear from GCMS studies that such derivatives with acetic and propionic acids are common in a broad range of plants including mulberry, Baphia, and English bluebells, but that they are very difficult to purify. Reaction of unprotected pyrrolidine iminosugars with aqueous glyoxal gives the corresponding N-acetic acids in very high yield; Michael addition of both pyrrolidine and piperidine iminosugars and that of polyhydroxylated prolines to tert-butyl acrylate give the corresponding N-propionic acids in which the amino group of ß-alanine is incorporated into the heterocyclic ring. These easy syntheses allow the identification of this new class of amino acid in plant extracts and provide pure samples for biological evaluation. DMDP N-acetic and propionic acids are potent α-galactosidase inhibitors in contrast to potent ß-galactosidase inhibition by DMDP.

A concise stereoselective synthesis of (-)-erycibelline.

(-)-Erycibelline, the dihydroxynortropane alkaloid isolated from Erycibe elliptilimba Merr. et Chun., was synthesized using a cyclic nitrone as advanced intermediate, wherein the key step was the SmI(2)-induced intramolecular reductive coupling of cyclic nitrone with aldehyde which resulted in good yield and stereoselectivity.

2,5-Dideoxy-2,5-imino-d-altritol as a new class of pharmacological chaperone for Fabry disease.

Chromatographic separation of the extract from roots of Adenophora triphylla resulted in the isolation of two pyrrolidines, six piperidines, and two piperidine glycosides. The structures of new iminosugars were elucidated by spectroscopic methods as 2,5-dideoxy-2,5-imino-d-altritol (DIA) (2), beta-1-C-butenyl-1-deoxygalactonojirimycin (8), 2,3-dideoxy-beta-1-C-ethyl-1-deoxygalactonojirimycin (9), and 6-O-beta-d-glucopyranosyl-2,3-dideoxy-beta-1-C-ethyl-1-deoxygalactonojirimycin (10). beta-1-C-Butyl-1-deoxygalactonojirimycin (7) and compound 8 were found to be better inhibitors of alpha-galactosidase than N-butyl-1-deoxygalactonojirimycin. The present work elucidated that DIA was a powerful competitive inhibitor of human lysosome alpha-galactosidase A (alpha-Gal A) with a K(i) value of 0.5muM. Furthermore, DIA improved the thermostability of alpha-Gal A in vitro and increased intracellular alpha-Gal A activity by 9.6-fold in Fabry R301Q lymphoblasts after incubation for 3days. These experimental results suggested that DIA would act as a specific pharmacological chaperone to promote the smooth escape from the endoplasmic reticulum (ER) quality control system and to accelerate transport and maturation of the mutant enzyme.