Exploring the binding energies of new pyrazoline derivatives to DNA/BSA: antifungal, antioxidant, MD simulations and TD-DFT studies.

A new series of compounds (4a-4l) was synthesized from 4-methoxybenzaldehyde, 4-iodoacetophenone, and various substituted boronic acids using Pd(PPh3)4 as a catalyst. The synthesized compounds were characterized by 1H,13C-NMR, FT-IR, UV-visible spectroscopy, and mass spectrometry. Density Functional Theory (DFT) calculations were employed to determine their physicochemical parameters. The in vitro antifungal activity and hemolysis potential of the compounds were assessed against Candida species. Among the series, analogues 4h and 4i exhibited notable antifungal activity, as evidenced by their minimum inhibitory concentrations (MICs). Their interactions with calf thymus DNA (Ct-DNA) and bovine serum albumin (BSA) were studied using UV-visible, fluorescence, time-resolved fluorescence spectrophotometry, and cyclic voltammetry. The binding constants (Kb) of 4h and 4i with Ct-DNA were 9.06 × 105 ± 0.14 and 5.17 × 105 ± 0.26 M-1, and with BSA were 1.75 × 104 and 8.13 × 104 M-1, respectively. Corresponding Gibbs free energy values were -33.97 and -32.59 kJ mol-1. Stern-Volmer constants (KSV) for 4h and 4i were 6.91 × 104 ± 0.21 and 7.58 × 104 ± 0.36 M-1 with Ct-DNA, and 1.18 × 104 and 4.98 × 104 M-1 with BSA, respectively. Molecular docking studies with PDB IDs 1BNA and 5FSA confirmed the binding interactions, supported further by 50 ns molecular dynamics (MD) simulations, which revealed RMSF values for all binding residues under 1.3 Å. Additionally, antioxidant assays (DPPH and H2O2) demonstrated good activity for 4h and 4i.