Antagonistic Effect Of Epicatechin On Lead Intoxication In Mice

Lead（Pb）is the main source of heavy metal pollution in food,which is easy to accumulate in the body and has adverse effects on the blood system,nervous system,liver,and kidney.However,Pb poisoning has not been well resolved,so it is urgent to seek new dietary strategies for protection.Epicatechin（EC）is a natural polyphenol with anti-oxidation,chelating metal ions,protecting the nervous system,and protecting liver and kidney damage.It is worth noting that whether EC could alleviate Pb-induced blood damage,nerve damage,liver and kidney damage and,its probable protective mechanisms are still unclear.Thence,this study aimed to explore the protective effect of EC on Pb-induced impairment in mice and its underlying mechanism.First,Kunming mice were treated with PbCl₂（20 mg/kg bw）by gavage for 4 weeks to establish a Pb exposure model,and the mice were given EC（50 mg/kg bw）intervention.To evaluate the effect of EC on learning and memory function in Pb-induced mice and its protective effect on oxidative stress injury in erythrocytes,brain,liver and kidney.The results showed that EC could restore brain tissue function by activating the Nrf2 signaling pathway and significantly improve the impairment of learning and memory in lead-induced mice.In addition,EC could alleviate Pb-induced damage to erythrocytes,liver and kidney functions by reducing oxidative stress.At the same time,EC could reduce the accumulation of Pb in the body and promote the excretion of Pb,indicating that EC might affect the distribution and transport of Pb in the body.Based on the observation that EC reduced the level of Pb in serum,the main carrier protein（serum albumin）in plasma was selected as the research object.Through multispectral analysis,potentiometric titration and molecular docking,two schemes of EC,Pb²⁺,BSA ternary system were comprehensively compared.The interference mechanism of EC on the interaction between BSA and Pb²⁺was explored in vitro.It was found that EC could affect the interaction between BSA and Pb²⁺,indicating that EC has the potential to interfere with the transport of Pb in vivo.BSA interacted with Pb²⁺to form a complex,and EC bound to BSA in a non-competitive manner to form a new ternary complex.Thus,the conformation of BSA and the microenvironment of tryptophan residues was changed,and the influence on luminescent groups was weakened.Furthermore,Pb²⁺could form a stable complex with EC.Compared with the interaction between BSA and Pb²⁺,the binding affinity of Pb²⁺-EC complex to BSA was significantly reduced,the binding distance was increased,the binding site was shifted,and the interaction mode was changed from electrostatic interaction to hydrogen bond interaction.Therefore,Pb²⁺-EC complex had less influence on the conformation of BSA.In conclusion,the antagonism of EC on Pb exposure was jointly demonstrated at the animal and protein levels,which provided research ideas for food-borne phenolic compounds to antagonize the harm of heavy metals.