Sustainable Synthesis of 1,2-Disubstituted Benzimidazoles as Promising α-Glucosidase Inhibitors: In Vitro and In Silico Evaluation

Background: Inhibiting alpha-glucosidase and alpha-amylase is a well-established strategy for managing postprandial hyperglycemia in type 2 diabetes mellitus. However, the adverse effects of current alpha-glucosidase inhibitors (alpha-GIs) underscore the need for safer alternatives. Methods: This study introduces an efficient, metal-free, and environmentally friendly protocol for the selective, high-yield synthesis of 1,2-disubstituted benzimidazoles. The reaction between o-phenylenediamine and various aromatic aldehydes proceeds smoothly in water at room temperature, using cost-effective and eco-friendly catalysts such as acetylsalicylic acid (ASA) or salicylic acid (SA). The methodology exhibits broad versatility, enabled by the use of different o-phenylenediamines and a wide range of aromatic and heteroaromatic aldehydes. Results: Selected compounds were assessed for their inhibitory activity against alpha-glucosidase and alpha-amylase. While all exhibited low alpha-amylase inhibition, several showed significant alpha-glucosidase inhibition, with compounds 8s (IC50 = 0.39 +/- 0.04 mu M), 8k (IC50 = 7.4 +/- 1.6 mu M) and 8r (IC50 = 13.8 +/- 2.7 mu M) emerging as the most promising candidates. Notably, none of these compounds affected Caco-2 cell viability at concentrations up to 30 mu M. Additionally, compounds 8r and 8s exhibited antioxidant properties, which may be relevant in counteracting the excessive production of free radicals associated with diabetes. Preliminary molecular docking and 500 ns molecular dynamics (MD) simulations were carried out on compounds 3k, 8i, 8k, and 8p-8s to support and interpret the experimental biological findings qualitatively.