Salacinol and kotalanol are new class of potent glycosidase inhibitors, isolated by presenters from Ayruvedic traditional medicine Salacia reticulata, having the unique zwitter-ionic structure comprising of 1-deoxy-4-thio-D-arabinofranosyl cation and the sulfate anion in the alditol side chain. Elucidation of the stereostructure of kotalanol, which has long been unknown and very recently approved by Pinto and co-workers by the synthesis, by the independent manner involving the degradation of natural kotalanol is presented. In the detradation of 2, characteristic deprotective cyclization of heptitols to anhydroheptitols was found to occur to a large extent. Structural elucidation of salalprinol, one of the sulfonium analogs recently isolated from the same species, by the synthesis is also presented. Revisions of the structures of new constituents from Salacia species, neosalacinol and 13-membered cyclic sulfoxide, recently reported as constituents responsible for the α-glucosidase inhibitory activity by Minami and Osaki and co-workers, respectively, are presented. In relation to this study, synthetic route of de-O-sufonated salacinol, which was proved as potent as 1, has been developed. Finally, conditions for the quantitative analysis of 1, 2, and their de-O-sulfonates (3 and 4) by LC-MS for the qualitative evaluation of Salacia extracts is discussed.
