Discovery of α-glucosidase inhibitors from Paenibacillus sp. JNUCC 31 via genome mining, fatty acid profiling, and in silico analysis

The increasing prevalence of type 2 diabetes has driven an increasing demand for safe and effective α-glucosidase inhibitors (AGIs). Given prior findings of α-glucosidase inhibitory activity in Paenibacillus spp., this study aims to evaluate the biosynthetic capacity and inhibitory potential of Paenibacillus sp. JNUCC 31. Genomic annotation of the strain JNUCC 31 revealed multiple biosynthetic gene clusters associated with secondary metabolite biosynthesis. Fatty acid profiling initially identified anteiso-C15:0 (57.32%) as the dominant fatty acid via GC-MS. Subsequently, the ethyl acetate extract from fermented cultures, which exhibited the highest α-glucosidase inhibitory activity (52.4 ± 0.7%), was purified and five known compounds were isolated: adenosine, uridine, 4-hydroxybenzaldehyde, dibutyl phthalate (DBP), and 1-acetyl-β-carboline. Among these, adenosine, uridine, and DBP have been previously reported as α-glucosidase inhibitors. Enzyme kinetics confirmed that uridine (K_i = 153.35µM) functions as a competitive inhibitor, while adenosine (K_i = 90.88µM) and DBP (K_i = 516.22µM) act via a mixed-type inhibition mechanism. Molecular docking and molecular dynamics simulations demonstrated stable binding of these active compounds to human maltase-glucoamylase (MGAM, PDB ID: 2QMJ) and microbial isomaltase (PDB ID: 3A4A). Molecular Mechanics/Generalized Born Surface Area (MM/GBSA) analysis indicated favorable binding free energies (- 14.18 to - 36.5 kcal/mol), with key residues such as Trp406 (MGAM), Tyr158 and Gln279 (isomaltase) playing major roles in binding stabilization. Collectively, these findings highlight the strain JNUCC 31 as a promising microbial source of antidiabetic lead compounds.