Inhibition of naringinase (L-rhamnosidase) by piperidine analogues of L-rhamnose: Scaffolds for libraries incorporating trihydroxypipecolic acids

Synthesis of Nitrone-derived Pyrrolidine Scaffolds and Their Combinatorial Libraries to Develop Selective α-l-Rhamnosidase Inhibitors

A general and flexible approach toward the development of α-l-rhamnosidase (α-l-Rha-ase) inhibitors is described. Five enantiopure poly-substituted pyrrolidine-based scaffolds bearing the C1-aminomethyl moiety were designed and synthesized from five-membered cyclic nitrones. Each structurally diversified amide library of these scaffolds was rapidly generated via combinatorial parallel synthesis and applied for in-situ inhibition study against α-l-Rha-ase, allowing us to efficiently identify new inhibition hits. Surprisingly, all promising inhibitors are derived from the same scaffold 3. Among them, the most potent and selective inhibitor is pyrrolidine 19 with Ki =0.24 μM, approximately 24-fold more potent than the reference compound DAA (Ki =5.7 μM). It is the first study to comprehensively prepare pyrrolidine-based scaffolds and libraries for inhibition study against α-l-Rha-ase.

Amino-functionalized iminocyclitols: synthetic glycomimetics of medicinal interest

A review on the syntheses and biological activities of unnatural glycomimetics highlighting the effect of replacement of hydroxyl groups of natural iminosugars by amino functionalities is presented.

α-Rhamnosidase inhibitory activities of polyhydroxylated pyrrolidine

We designed and synthesized polyhydroxylated pyrrolidines 1-12 from L-tyrosine, L-phenylalanine, and D-tyrosine through iodine-mediated intramolecular cyclization followed by Woodward-Prevost reaction. The synthetic polyhydroxylated pyrrolidines were identified with structure-based inhibitory activity and selective inhibitory activity against alpha-rhamnosidase. (2S,3S,4R)-deacetyl anisomycin 7 was the best inhibitor among the 12 polyhydroxylated pyrrolidines because it possesses the same stereoconfiguration at C1, C2, C3 as alpha-L-rhamnopyranoside. An investigation into the nature of the inhibition showed that the synthetic pyrrolidines are competitive inhibitors. They also did not have remarkable inhibitory activity against seven glycosidases (alpha-glucosidase, alpha-mannosidase, alpha-amylase, beta-glucosidase, beta-galactosidase, beta-amylase, and invertase).

Asymmetric synthesis of (-)-swainsonine, (+)-1,2-di-epi-swainsonine, and (+)-1,2,8-tri-epi-swainsonine

The asymmetric synthesis of (-)-swainsonine via a nonchiral pool route that involves the Sharpless epoxidation to induce chirality is reported. The key steps involve vinyl epoxide aminolysis, ring-closing metathesis, and intramolecular N-alkylation to prepare the indolizidine ring and a highly diastereoselective cis-dihydroxylation using AD-mix-alpha. This synthetic strategy also allowed for the diastereoselective synthesis of (+)-1,2-di-epi-swainsonine and (+)-1,2,8-tri-epi-swainsonine.