In this study, the synthesis of polyphenol oxidase (PPO)-functionalized aluminum oxide (Al 2 O 3 ) nanoconjugates (NCs) using Pleurotus ostreatus extracts has been carried out, which also assesses their antioxidant, phenolic degradation, and molecular interaction capabilities through the combined experimental and computational methods. PPO extraction optimization showed optimal enzyme activity (maximum of 130 U/mL) to be at 3% biomass concentration, 25 mL of extractant, 120 minutes of incubation time, and 40℃. The structural characterization revealed that PPO was successfully synthesized onto Al 2 O 3 NCs, and the presence of crystalline Al 2 O 3 NCs phases, enzyme-to-nanoparticle interactions via Fourier transform infrared spectroscopy (FTIR), morphology (spherical to global) via scanning electron microscopy (SEM), and particle sizes (nanoscale) via dynamic light scattering process (DLS) were found. PPO-coated Al 2 O 3 NCs performed better antioxidant capacity, with the highest diphenyl-1-picrylhydrazyl (DPPH) radical scavenging rate of 66.64 ± 3.33%, which was better than both the free Al 2 O 3 NCs and the natural antioxidant ascorbic acid in the same solution. The use of immobilized Al 2 O 3 NCs in assays of phenolic wastewater treatment showed better degradation efficiency, which yielded a 1.69-fold increase in enzyme activity under fluorescent light and a 1.86-fold increase in enzyme activity under photocatalytic conditions, suggesting an effective catalytic turnover and adsorption of the pollutant. Molecular docking showed that the phenolics in mushrooms had a high binding affinity with PPO-related targets, and rutin (-123.16 kcal/mol), catechin (-118.90 kcal/mol), and apigenin (-118.23 kcal/mol) had significantly high binding affinities compared with ascorbic acid (-85.22 kcal/mol). The adsorption, distribution, metabolism, excretion (ADME), and toxicity studies confirmed positive pharmacokinetics and low predicted toxicity in lead compounds, and density functional theory (DFT) calculations revealed reduced highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) energy gaps and increased electronic reactivity in apigenin as compared to ascorbic acid. Taken together, these results ensure the use of PPO-coated Al 2 O 3 NCs as an efficient, sustainable, and multi-functional platform of antioxidant applications and phenolic wastewater treatment.
Islam et al. (Fri,) studied this question.