Myeloperoxidase (MPO)-mediated oxidative stress has been suggested to play an important role in the pathological dysfunction of epileptic brains. Some current studies have shown that an increase in the levels of MPO is associated with epileptogenesis, suggesting that MPO might be a promising biomarker for the early diagnosis of epilepsy and could also serve as a potential therapeutic target for epilepsy. However, there is currently no robust brain imaging tool to detect real-time endogenous hypochlorite (HClO) generation by MPO or a fluorescent probe for rapid high throughput screening of antiepileptic agents that control the MPO-mediated chlorination stress. Recently, the research group led by Professor Yong Qian of the School of Chemistry and Materials Science at NNU has made significant progress in epilepsy-related neurochemistry and biology. This research group, together with Professor Jin Zhao and Professor Hailiang Zhu from Nanjing University, published their result in Proceedings of the National Academy of Sciences of the United States of America (PNAS), an internationally authoritative journal, and the paper was titled “Epileptic brain fluorescent imaging reveals apigenin can relieve the myeloperoxidase-mediated oxidative stress and inhibit ferroptosis”.
To achieve the real-time detection of HClO generation by MPO in live brains in animal models, the designed activity-based sensing probe should be noncytotoxic, have blood-brain barrier (BBB) penetrability, and have bright fluorescence. Taking into account the properties of the various fluorophores, the quinoline skeleton has attracted the researchers’ great interest because of its drug-like physicochemical and photophysical properties. This probe, named HCP, exhibited efficient BBB penetrability and two-photon fluorescence imaging. This study enables the sensitive detection and imaging of HClO generation by MPO in live brains without interference from other biological species. Importantly, the dynamic changes of endogenous HClO fluxes in brains were directly monitored during the therapeutic process of kainic acid (KA) -induced epileptic mice in vivo and ex vivo, Furthermore, by combining with high-content analysis, a simple high-throughput screening approach for antiepileptic agents was easily constructed, and apigenin was screened and confirmed as an efficient lead compound for epilepsy prevention and treatment. Further, we discovered that SIRT1 inactivation by MPO generated HClO might be a possible pathological mechanism for epileptogenesis; while apigenin can relieve the MPO-mediated oxidative stress for inhibition of ferroptosis, thereby promoting the antiepileptic functions. This work not only provides a robust fluorescent tool for understanding the pathological mechanism of MPO-generated HClO fluxes associated with neurodegenerative disease, but also illustrates a versatile strategy for accelerating the discovery of small molecular agents for antiepileptic prevention and treatments.
Epilepsy is one of the five major neuropsychiatric diseases, whose prevalence is only second to cerebral stroke. At present, early diagnosis and treatment of epilepsy are still the most effective method for prevention and treatment. High-level oxidative stress in cells including abnormal increase of reactive oxygen, nitrogen and carbon (ROS / RNS / RCS) is closely related to the occurrence and development of epilepsy. It has an important scientific significance on the diagnostic imaging, chemical intervention and regulation of oxidative stress in live brains. In recent years, focusing on the research of "diagnostic imaging and chemical regulation of key biomolecules and disease markers related to oxidative stress", Professor Yong Qian's team developed a series of original technologies such as RNS probe ONP and RCS probe FAP, and constructed a high-throughput live cell drug screening platform, which is used for rapid screening of epilepsy drug candidates and in-situ real-time detection of biological samples. A series of research results were published in 2019 Adv Sci, 2017 Chem Sci, 2020 Chem Commun. The series of research not only provides innovative neurochemical and biological research tools for in-depth understanding of the pathological mechanisms of epilepsy and other clinically major diseases, but also provides high-throughput screening technical support for the further development of new drugs to prevent and treat neurodegenerative diseases.
This study was supported by the General Program of National Natural Science Foundation of China, Project of Distinguished Professor of Jiangsu Province and other scientific research projects. Dr. Chenwen Shao and Dr. Jiwen Yuan are the co-first authors, Prof. Yong Qian, Prof. Jin Zhao and Prof. Hailiang Zhu from Nanjing University are co-corresponding authors. Nanjing Normal University is the first corresponding author’s affiliation. The study also received great help from Prof. Guiquan Chen from the Model Animal Research Center of Nanjing University, Prof. Bing Zhang from the Nanjing Drum Tower Hospital, Prof. Hongke Liu from Nanjing Normal University and Dr. Yajuan Qin from Nanjing Medical University.