In vitro effects of standard antioxidants on lactoperoxidase enzyme–A molecular docking approach

Lactoperoxidase (LPO), an antioxidant enzyme, is a natural antimicrobial system that eliminates the harmful effects of microorganisms in milk. It has a wide range of applications and is also preferred in cosmetic and clinical applications, as well as used in foods. The use of antioxidants is well recognized in the food and feed industries to improve the shelf life of products. This study aimed to determine the in vitro inhibition effects of Trolox, α‐tocopherol, butylated hydroxyanisole, butylated hydroxytoluene, and propyl gallate, which are commonly used as antioxidants in food and pharmaceutical products. For this purpose, LPO was first purified in a single step using sepharose‐4B‐l ‐tyrosine‐sulfanilamide affinity gel chromatography. Also, some inhibition parameters, including half‐maximal inhibitory concentration (IC₅₀), K_i values, and inhibition types, were calculated for each antioxidant molecule. The IC₅₀ values of these molecules, which exhibited competitive inhibition, varied between 377.7 and 3397.8 nM. Molecular docking studies were also performed for all compounds. According to the binding scores, α‐tocopherol was shown to exhibit the most effective inhibitor property (IC₅₀: 377.7 nM and K_i: 635.8 ± 16.8 nM) among the standard antioxidants used in this study. Inhibiting the LPO activity by standard antioxidants results in the weakening of the immune system during lactation, which is important for metabolism.