Lactoperoxidase inhibition by some carnosol and carnosic acid derivatives: In vitro, In silico and statistical approaches

Abstract

Lactoperoxidase (LPO) is an important milk enzyme with oxidoreductase activity. The in vitro inhibition kinetics of carnosol, a diterpenoid present in Rosemary, and its derivatives were investigated on LPO. Firstly, chromatographic techniques were used to purify LPO with a specific activity of 806.451 EU/mg protein. Secondly, inhibition kinetics were assayed in the presence of the compounds. Thirdly, molecular docking was performed to predict the inhibition mechanism. Lastly, the statistical analysis was done for inhibitors. The molecules showed noncompetitive inhibition except for 12-methylcarnosic acid with the Ki values between 34.64 +/- 1.93-392.9 +/- 59.3 mu M. Isorosmanol was predicted to have the highest affinity on the LPO receptor, with estimated free binding energies of -8.69 kcal/mol. The statistical model showed that the inhibition of the molecules was dependent on the hydroxylation at position C7, methylation of hydroxyl group at C12, and carboxylation at C5.