Mechanistic inhibition of non-enzymatic glycation and aldose reductase activity by naringenin: Binding, enzyme kinetics and molecular docking analysis

The aldose reductase (AR) enzyme is considered a potential target for the management of diabetic complications. In this study, we describe the binding and enzyme kinetics of AR by naringenin, a bioflavonoid present in many dietary sources. Naringenin showed an inhibitory effect on the activity of AR with an IC₅₀ value of 2.6 μM in an uncompetitive manner. Binding studies confirmed that the naringenin-AR complex has high spontaneous affinity (K_a = 1.94–7.88 × 10⁴) with negative ΔG° value (−5.78 kcal mol⁻¹). The interaction was enthalpy driven and the microenvironment of aromatic residues of AR was also altered. Various stages of protein oxidation and glycation were also measured. Naringenin inhibited fructosamine content by approximately 31.6% at 10 μM, and at the same concentration, >93% inhibition of fluorescent advanced glycation end-products (AGEs) was achieved. There was a significant recovery in free thiol groups and carbonyl content of bovine serum albumin (BSA). Furthermore, molecular docking of naringenin with AR revealed that naringenin formed two hydrogen bonds (Asn160 and Ile260), and three Pi-Pi interactions (two with Trp20 and one with His110). This study provides molecular insight of naringenin-AR interaction and mechanism of antiglycation which may be useful in the development of inhibitors for AGEs formation.