Kinetics Studies on the Inhibition Mechanism of Pancreatic α‐Amylase by Glycoconjugated 1 H ‐1,2,3‐Triazoles: A New Class of Inhibitors with Hypoglycemiant Activity

• Published in: Chembiochem : a European journal of chemical biology 2012-07, Vol.13 (11), p.1584-1593
• Main Authors: Senger, Mario Roberto, Gomes, Lucas da Costa Andrade, Ferreira, Sabrina Baptista, Kaiser, Carlos Roland, Ferreira, Vitor Francisco, Silva, Floriano Paes
• Format: Article
• Language: English
• ISSN: 1439-4227; 1439-7633
• DOI: 10.1002/cbic.201200272

Glycoconjugated 1 H ‐1,2,3‐triazoles (GCTs) comprise a new class of glycosidase inhibitors that are under investigation as promising therapeutic agents for a variety of diseases, including type 2 diabetes mellitus. However, few kinetics studies have been performed to clarify the mode of inhibition of GCTs with their target glycosidases. Our group has previously shown that some methyl‐β‐ D ‐ribofuranosyl‐1 H ‐1,2,3‐triazoles that inhibit baker's yeast maltase were also able to reduce post‐prandial glucose levels in normal rats. We hypothesized that this hypoglycemiant activity was attributable to inhibition of mammalian α‐glucosidases involved in sugar metabolism, such as pancreatic α‐amylase. Hence, the aim of this work was to test a series of 26 GCTs on porcine pancreatic α‐amylase (PPA) and to characterize their inhibition mechanisms. Six GCTs, all ribofuranosyl‐derived GCTs, significantly inhibited PPA, with IC 50 values in the middle to high micromolar range. Our results also demonstrated that ribofuranosyl‐derived GCTs are reversible, noncompetitive inhibitors when using 2‐chloro‐4‐nitrophenyl‐α‐ D ‐maltotrioside as a substrate. E/ES affinity ratios ( α ) ranged from 0.3 to 1.1, with the majority of ribofuranosyl‐derived GCTs preferentially forming stable ternary ESI complexes. Competition assays with acarbose showed that ribofuranosyl‐derived GCTs bind to PPA in a mutually exclusive fashion. The data presented here show that pancreatic α‐amylase is one of the possible molecular targets in the pharmacological activity of ribofuranosyl‐derived GCTs. Our results also provide important mechanistic insight that can be of major help to develop this new class of synthetic small molecules into more potent compounds with anti‐diabetic activity through rational drug design.