【NHF Forum No.164】Substrate-inspired and structure-based discovery of enzyme inhibitors

报告题目：Substrate-inspired and structure-based discovery of enzyme inhibitors 

报  告 人：Prof. Stanislav Gobec (University of Ljubljana, Slovenij)

时      间：2018年11月19日（周一）下午3:00-5:00

地      点：南楼三层会议室 

邀 请 人：宫建茹 研究员 

报告摘要：

Development of small molecule inhibitors of therapeutically relevant enzymes is the main focus of our research group at the Faculty of Pharmacy, University of Ljubljana. Two cases of inhibitor development will be presented where different approaches were used: substrate-inspired approach was used for development of Mur enzyme inhibitors, and structure-based approach was used in discovery and optimization of butyrylcholinesterase inhibitors.

The widespread emergence of resistant bacterial strains is becoming a serious threat to public health. This signifies the need for the development of new antibacterial agents with novel mechanisms of action. Bacterial peptidoglycan is a major component of the bacterial cell wall, and it provides rigidity and enables bacteria to survive in hypotonic environments. As intact peptidoglycan is essential for bacterial survival, all of the peptidoglycan biosynthesis steps are considered to be important targets for the discovery of new antibacterial agents. In the history of antibacterial drug discovery, the attention has mostly been focused on the late stages of peptidoglycan biosynthesis that are catalyzed by transpeptidases and inhibited by important antibiotics, such as penicillins and cephalosporins. However, attention has recently shifted also towards the cytoplasmatic steps of peptidoglycan biosynthesis, and especially towards the Mur enzymes. In this respect, the Mur enzymes, MurA-F, that are involved in the formation of UDP-N-acetylmuramyl-pentapeptide can be genuinely considered as promising antibacterial targets. Our recent developments in the field of inhibitors of the MurA-F enzymes will be presented, where substrate-inspired approach has been the most successful. Moreover, the reasons for the lack of preclinically successful inhibitors and the challenges to overcome these hurdles in the next years will also be debated.

Alzheimer’s disease (AD) is characterized by severe basal forebrain cholinergic deficit, which results in progressive and chronic deterioration of memory and cognitive functions. Similar to acetylcholinesterase, butyrylcholinesterase (BChE) contributes to the termination of cholinergic neurotransmission. Its enzymatic activity increases with the disease progression, thus classifying BChE as a viable therapeutic target in advanced AD. Potent, selective and reversible human BChE inhibitors were developed. First, a hierarchical virtual screening was performed followed by biochemical evaluation of highest scoring hit compounds. Three compounds showed significant inhibitory activities against BChE and the best inhibitor was selected for further SAR studies. More than 100 different analogues were synthesized and among them, two compounds were found to be promising lead compounds as they were not cytotoxic, they crossed the blood-brain barrier and improved memory, cognitive functions and learning abilities of mice in a model of the cholinergic deficit that characterizes AD, without producing acute cholinergic adverse effects. The solved crystal structures of human BChE in complex with the most potent inhibitors revealed their binding modes and provided the structural basis for their further development into multi-target-directed ligands, which in addition to good inhibition of BChE possess good antioxidant, metal chelating, neuroprotective and other properties beneficial for AD.