Antityrosinase mechanism of omeprazole and its application on the preservation of fresh-cut Fuji apple

Omeprazole was first evaluated for its antityrosinase activity and preservation of fresh-cut apples. The results obtained from enzymic analyses showed that the omeprazole inhibited tyrosinase activity ( IC 50  = 40 ± 1.2 μM) with a reversible and competitive mechanism. Fluorescence quenching assays demonstrated that the interaction between omeprazole and tyrosinase was driven by hydrophobic forces and hydrogen bonds in a static procedure. Molecular docking further revealed that hydrogen bonds and hydrophobic forces were generated by omeprazole with the amino acid residues located in the A chain of tyrosinase. Moreover, the results from preservation assays showed that omeprazole could inhibit the activities of polyphenol oxidase (PPO) and peroxidase (POD), prevent the oxidation of total phenolics and flavonoid , thereby delay the browning of fresh-cut apples. Hence, this work identified a novel tyrosinase inhibitor and expands its feasible application as a food preservative.