Fluorescence enhancement and quenching study: Interaction of diosgenin with biologically significant macromolecules

Abstract

Diosgenin, a naturally occurring steroidal sapogenin, has drawn increasing attention due to its broad pharmacological potential. In this study, we investigated its binding interactions with three biologically significant macromolecules: calf thymus DNA (CT-DNA), human serum albumin (HSA), and trypsin. The effects of the diosgenin on the structure and activity of these macromolecules were carried out using fluorescence spectroscopy (type of quenching, binding constant, number of binding locations, thermodynamic parameters, synchronous fluorescence, FRET analysis, 2D, and 3D fluorescence analysis, effect of metal ions), FTIR and molecular docking techniques. The results show that the diosgenin could bind to CT-DNA via a minor groove mode. The fluorescence experiments indicated that the diosgenin binding causes enhancement of HSA fluorescence while the diosgenin binding causes quenching of trypsin fluorescence. Experimental binding studies were conducted to assess the diosgenin's interaction profile, complemented by molecular docking simulations to provide structural insight into the binding modes. Docking results indicated that the diosgenin forms stable complexes with all three targets, exhibiting the highest affinity toward HSA (–10.5 kcal/mol), followed by DNA (–9.0 kcal/mol) and trypsin (–8.1 kcal/mol). The diosgenin was found to bind along the minor groove of DNA, interact with subdomain IB of HSA, and settle within the catalytic pocket of trypsin. In silico analyses indicated high oral absorption, good permeability, and no major toxicity risks, supporting the diosgenin's drug-likeness and multi-target potential. The antioxidant effectiveness of the diosgenin was measured via the DPPH method and reported in terms of its EC₅₀ value.