Discovery of Antioxidant Peptide Against Keap1 From <i>Silkworm</i> Protein Based on In Silico Study and In Vitro Antioxidant Activity Detection

Nrf2-Keap1 is an important defense system against oxidative stress damage and enhances the body's antioxidant capacity. Targeting the Keap1-Nrf2 signaling pathway and activating Nrf2 has become an effective strategy for treating oxidative stress and related diseases. In this study, virtual digestion, ADMET prediction, and molecular docking were used to screen antioxidant peptide from silkworm pupa protein. Then, a novel tripeptide (WQK) was identified, exhibiting good water solubility, nontoxicity, high intestinal absorption, and the ability to cross the blood-brain barrier. Molecular docking showed that WQK established six H-bond interactions with some key sites of Keap1 (Arg380, Arg415, Gln530, Ser555, Ile416, and Leu365), which is similar to the identified antioxidant molecule 12e. Additionally, WQK has the function to reduce ABTS·⁺ and ferric-tripyridyltriazine (Fe³⁺-TPTZ) in vitro. Furthermore, WQK can promote the expression of antioxidant genes and eliminate reactive oxygen species (ROS) in oxalic acid-treated human proximal tubular epithelial cells (HK-2). The results suggested that WQK may activate the Keap1-Nrf2 signaling pathway by binding to Keap1 and activating the antioxidant system.