Corrosion and biological inhibition activity studies of O-allylated syringic acid derivatives via computational approaches

Syringic acid (SA) is a naturally occurring phenolic compound with known antioxidant, anti-inflammatory, antimicrobial, and anticancer properties. Phenolic acids derived from natural sources have attracted growing research interest owing to their diverse pharmacological and industrial applications. Three O-allylated derivatives, allyl 4-hydroxy-3,5-dimethoxybenzoate (AS1), diallyl 2,6-dimethoxyterephthalate (AS4AE), and 4-(allyloxy)-3,5-dimethoxybenzoic acid (SA4AE), were evaluated for their corrosion inhibition and biological activities using computational methods. Geometry optimization was performed at the B3LYP/6-311G level of DFT theory. Frontier molecular orbital (FMO) energies, global reactivity descriptors, and condensed Fukui indices were extracted to characterize their electronic behaviour and local reactivity properties. A molecular docking study of the inhibitors against the adenosine A 1 AR receptor was conducted, followed by a 100 ns molecular dynamics simulation. Physicochemical and pharmacokinetic profiling was employed to assess their biomedical properties. Corrosion inhibition on the Fe(110) surface was assessed through Monte Carlo adsorption and quench molecular dynamics simulations using the COMPASS II force field. SA4AE emerged as the most reactive derivative (ΔE = 6.35 eV), while AS1 showed the greatest tendency to donate electrons (E HOMO = − 7.07 eV). Methoxy atoms and ring carbons were identified as the main nucleophilic sites. All three compounds met Lipinski’s drug-likeness rules, showed favourable predicted intestinal absorption, and posed no mutagenicity risk. AS4AE matched adenosine’s binding affinity (− 7.3 kcal/mol) and proved the strongest corrosion inhibitor, with an adsorption energy of − 5520 kcal/mol.