Antioxidant activity, enzyme inhibition, electrochemical and theoretical evaluation of novel PEPPSI type N-heterocyclic carbene complexes

Abstract

N-Heterocyclic carbenes have attracted attention due to their strong sigma-donor and weak pi-acceptor properties since they were first isolated. Pyridine is also found in many natural products and is included in the content of many pharmaceutical molecules. Palladium complexes containing two halogens, a pyridine and an N-heterocyclic carbene have been identified as PEPPSI (Pyridine-Enhanced Precatalyst Preparation Stabilization and Initiation). Although Alzheimer Disease is thought to be affected by environmental and genetic factors, it has not been fully elucidated. There are various mechanisms used to explain the pathogenesis of this disease which guide the design of new drugs. In Alzheimer Disease cases, acetylcholinesterase activity decreases while butyrylcholinesterase increases and disproportionate reactive oxygen species is also recorded. So, the drug used in Alzheimer Disease treatment must have more than one function, that is, the molecule is expected to be effective in both acetylcholinesterase/butyrylcholinesterase balance and antioxidant activity. In this study, PEPPSI type complexes were synthesized and characterized. The structural, electronic, and reactivity properties of the molecules were analyzed by DFT-based calculation methods and Koopman’s Theory. The inhibition activities against acetylcholinesterase, butyrylcholinesterase and tyrosinase were also analyzed, and the antioxidant activity of the molecules were investigated. The inhibition and the activity details of the molecules were also evaluated by molecular docking methods.