Antioxidant peptides can be obtained from diverse dietary protein sources with high safety. The Kelch-like ECH-associated protein 1(Keap1) is a key protein in the cellular oxidative stress signaling pathway and it plays an important role in the field of antioxidant. Soybeans are a vital source for the production of bioactive peptides. In this study, firstly, we screened 468 antioxidant peptides from soybean protein with low molecular weight, high hydrophobicity and non-toxicity. The top three antioxidant peptides were isolated and extracted from the fractions using UHPLC-QQQ/MS analysis. The free radical scavenging rate demonstrated significant antioxidant activity of PHHADS (EC 50 = 4.26 mmol/L). In addition, peptide PHHADS was demonstrated significantly protects HepG2 cells from oxidative stress-induced damage. Lastly, 200 ns molecular dynamics simulations were performed between the peptides and Keap1. The results revealed that PHHADS closely interacts with the active site of Keap1. Moreover, the interaction of the antioxidant peptides with Keap1 led to the disruption of the β-sheet structure of Keap1 in residues380-390, transforming into an irregularly curved structure. This particular region in Keap1 is crucial for substrates binding, suggesting a potential inhibitory mechanism by the peptides. These findings contribute to the understanding of antioxidant peptide interactions and their potential application in developing functional foods for health benefits.
Jia-Yi Weng,Jia-Yu Yang,Ishimwe Steven Papy,Bu-Tao Yu,Yu-Feng Ke,Bing-Yu Bai,Mitchell N. Muskat,Qian Wu,Xiang-Rong Cheng
Cinnamaldehyde (CA) is the key component of the essential oil derived from cinnamon bark and recommended as a health factor in foods for the prevention and intervention of metabolic disorders. This research aims to reveal the association between the difference in the electrophilic abilities of functional groups in CA and 3-phenylpropionaldehyde (PA), and their regulation of lipid peroxidation as well as energy metabolism in free fatty acids (FFAs) overloaded HepG2 cells. CA treatment reduced lipid accumulation and synthesis-related factors, increased levels of factors associated with fatty acid β-oxidation, decreased reactive oxygen species (ROS) content, and restored mitochondrial function and was superior to PA. Moreover, CA treatment increased nuclear Nrf2 protein levels and regulated the nuclear/cytoplasmic Nrf2 ratio, which suggested that CA effectively upregulated the Nrf2 signaling pathway. Furthermore, molecular docking showed that CA possessed an electrophilic index of 2.45 covalently bound to Nrf2-associated Keap1 protein with an affinity of −3.6 kcal/mol, which was much stronger than PA, and HPLC-MS/MS analysis further confirmed that CA covalently modified Cys151 on Keap1 protein. In conclusion, CA has the capacity to attenuate hepatic steatosis and cellular oxidative response via Nrf2 signaling pathway, which is closely related to its strong electrophilic ability.
The widespread abuse of antibiotics has led to the emergence of drug-resistant bacterial strains, severely complicating the treatment of infectious wounds. Traditional therapies are often limited to antibacterial or anti-inflammatory approaches, making it challenging to manage both early-stage infection and later-stage tissue regeneration simultaneously. Herein, a Cu 2−x Se nanoparticles (CSNPs) spray containing mixed-valence copper ions, enabling the programmed healing of infectious wounds is developed through light-controlled cascade regulation. In the early infection stages, the copper ions released from CSNPs exert antibacterial effects via chemodynamic therapy (CDT), with their activity significantly enhanced under near-infrared (NIR) irradiation. At later stages, Cu 2+ /Cu + ions enter cells, interact with cysteine residues in KEAP1 protein, and induce conformational changes, triggering deubiquitinase activity and suppressing macrophage-driven inflammation. Findings from in vitro and in vivo studies consistently revealed that CSNPs efficiently depleted glutathione and enhanced H 2 O 2 breakdown, leading to the generation of •OH and O 2 •- under NIR exposure, which resulted in an MRSA elimination rate exceeding 99%. Mechanistically, CSNPs bind to KEAP1, removing the ubiquitin linkage from NRF2, thereby inhibiting inflammation. This CSNPs spray provides a dual synergistic effect of antimicrobial and tissue-regenerative properties, offering an innovative approach for treating antibiotic-resistant infections in wounds.
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