Investigation on the influence of galloyl moiety to the peptidyl prolyl cis/trans isomerase Pin1: A spectral and computational analysis

Activation of Atg7-dependent autophagy by a novel inhibitor of the Keap1-Nrf2 protein-protein interaction from Penthorum chinense Pursh. attenuates 6-hydroxydopamine-induced ferroptosis in zebrafish and dopaminergic neurons

The death of dopaminergic neurons is a dominant factor during the occurrence and development of Parkinson's disease (PD). Previous studies demonstrated that ferroptosis is implicated in the death of dopaminergic neurons. Besides, polyphenols have been proven to be effective in preventing the death of dopaminergic neurons. This work aims to explore the neuroprotective effect and mechanism of thonningianin A (Th A), a polyphenolic compound in natural plant foods, against 6-hydroxydopamine (6-OHDA)-induced ferroptosis in dopaminergic cells. The results of molecular docking and other binding assays collectively demonstrated that Th A can strongly target the Kelch domain of Keap1. Th A treatment significantly facilitated the nuclear factor erythroid 2-like 2 (Nrf2) nuclear translocation and subsequently increased the heme oxygenase-1 (HO-1) protein level through inhibiting the protein-protein interaction (PPI) of Keap1 and Nrf2. Compared with the nomifensine (Nomi) treatment, Th A had a more potent protective effect on 6-OHDA-induced ferroptosis during PD pathology in zebrafish, which was associated with assuaging the reduction of the total swimming distance, glutathione (GSH) depletion, iron accumulation, lipid peroxidation, and aggregation of α-synuclein (α-syn). Furthermore, Th A also exhibited a strong protective effect against 6-OHDA-induced ferroptosis in vitro in the human neuroblastoma cell line SH-SY5Y. Th A degraded Keap1 protein through activating Atg7-dependent autophagy. Additionally, Th A treatment facilitated the degradation of Keap1 protein by promoting the interaction between p62/SQSTM1 (sequestosome 1, hereafter referred to as p62) and Keap1. Taken together, our findings indicated that Th A protects dopaminergic cells against 6-OHDA-induced ferroptosis through activating the Nrf2-based cytoprotective system, thus enabling a potential application of Keap1-Nrf2 PPI inhibitors in the restraint of ferroptosis and treatment of PD.

pH-Dependent complexation between β-lactoglobulin and lycopene: Multi-spectroscopy, molecular docking and dynamic simulation study

This study aims to investigate the effect of pH levels (pH 7.0 and pH 8.1) on binding ability of β-lactoglobulin (β-LG) with lycopene (LYC) and elucidate interaction mechanisms using multi-spectroscopy and molecular docking study. β-LG at pH 8.1 showed a stronger binding affinity to lycopene than that at pH 7.0 according to binding constant, binding number, energy transfer efficiency, and surface hydrophobicity. Lycopene bound to protein mainly by van der Waals force in the form of static quenching mode and preferred to interact with β-LG at the top of barrel for both pH levels. Molecular dynamic simulation revealed that β-LG/LYC complex at pH 8.1 was more stable than at pH 7.0. β-LG/LYC complexes formed at pH 8.1 showed significantly higher ABTS radical scavenging activity than samples at pH 7.0 (p < 0.05). Data obtained may contribute valuable information for preparing a whey protein-based delivery system for lycopene.