Vera C. M. Duarte

Advances in the synthesis of homochiral (-)-1-azafagomine and (+)-5-epi-1-azafagomine. 1-N-phenyl carboxamide derivatives of both enantiomers of 1-azafagomine: Leads for the synthesis of active α-glycosidase inhibitors.

A new expeditious preparation of homochiral (-)-1-azafagomine and (+)-5-epi-1-azafagomine has been devised. Stoodleys diastereoselective cycloaddition of dienes bearing a 2,3,4,6-tetraacetyl glucosyl chiral auxiliary to 4-phenyl-1,2,4-triazole-3,5-dione was merged with Bolss protocol for functionalizing alkenes into molecules bearing a glucosyl framework. Homochiral (+)-5-epi-1-azafagomine was synthetized for the first time. Partial reductive cleavage of the phenyltriazolidinone moiety afforded new homochiral 1-N-phenyl carboxamide derivatives of 1-azafagomine. Both enantiomers of these derivatives were synthetized and tested, displaying a very good enzymatic inhibition toward bakers yeast α-glucosidase. The molecular recognition mechanism of the 1-N-phenyl carboxamide derivative of 1-azafagomine by α-glucosidase from bakers yeast was studied by molecular modeling. The efficient packing of the aromatic ring of the 1-N-phenyl carboxamide moiety into a hydrophobic subsite (pocket) in the enzymes active site seems to be responsible for the improved binding affinity in relation to underivatized (-)-1-azafagomine and (+)-1-azafagomine.

Novel pyridine-2,4,6-tricarbohydrazide derivatives: Design, synthesis, characterization and in vitro biological evaluation as α- and β-glucosidase inhibitors

A range of novel pyridine 2,4,6-tricarbohydrazide derivatives (4a-4h) were synthesized and its biological inhibition towards α- and β-glucosidases was studied. Most of the compounds demonstrate to be active against α-glucosidase, and quite inactive/completely inactive against β-glucosidase. A number of compounds were found to be more active against α-glucosidase than the reference compound acarbose (IC50 38.25±0.12μM); being compound 4d with the p-hydroxy phenyl motive the most active (IC50 20.24±0.72μM). Molecular modeling studies show the interactions of compound 4d with the active site of target α-glucosidase kinase.

Synthesis and evaluation of α-, β-glucosidase inhibition of 1-N-carboxamide-1-azafagomines and 5-epi-1-azafagomines

1-N-Carboxamide 1-azafagomines and 5-epi-1-azafagomines were obtained from 1-azafagomine and 5-epi-1-azafagomine. The hydroxyl groups and the N-2 pyridazine position were protected prior to reaction with different isocyanates to form ureas. Protective groups were removed leading to the target compounds in 18-23% global yields. Final compounds were tested towards α- and β-glucosidases.

Molecular docking and glucosidase inhibition studies of novel N-arylthiazole-2-amines and Ethyl 2-[aryl(thiazol-2-yl)amino]acetates

This study describes an efficient synthesis of a series of novel ethyl 2-[aryl(thiazol-2-yl)amino]acetates (4a–l) from N-arylthiazole-2-amines (3a–l). The reaction conditions were optimized and the best results were obtained when ethyl chloroacetate was used as alkylating agent and NaH as base in THF. α-glucosidase and β-glucosidase inhibition activities of N-arylthiazole-2-amines (3a–l) and ethyl 2-[aryl(thiazol-2-yl)amino]acetates (4a–l) were determined, which revealed that most of the compounds showed high percentage inhibition towards the enzymes. Among the synthesized compounds, 4e appeared to have the highest inhibition towards α-glucosidase having IC50 value of 150.4 ± 1.9 μM which was almost two folds as compared to acarbose (336.9 ± 9.0 μM) taken as standard. Molecular docking of the compounds 3g, 3f, 4a, and 4e was also performed which showed their bonding modes to the enzyme’s active sites via amino and acetate groups, respectively.