Design, synthesis, and evaluation of dihydropyrimidinone (DHPM) based muscarinic receptor antagonist

摘要

Organophosphorus compounds (OPCs) are highly toxic being used in pest control. Some of the OPCs are lethal chemical warfare agents and their toxicity is due to inhibition of acetylcholine esterase (AChE), the enzyme that hydrolyses neurotransmitter acetylcholine (ACh). Due to over accumulation of ACh at muscarinic acetylcholine receptors (mAChRs) several cholinergic functions increase uncontrollably like salivation, lacrimation, urination, defecation, gastrointestinal upset, and emesis. Atropine is used to treat OPC poisoning because it is a mAChR antagonist. But atropine has several unwanted side effects including dryness of mucous membrane, hot and dry skin, tachycardia, and restlessness. Our goal was to find out molecules having antimuscarinic activity which may be developed as potential alternatives for atropine in future. In this work pharmacophore-based screening, structure identification, synthesis and ex vivo evaluation of a new class of muscarinic receptor antagonist are described. The antagonists are based on dihydropyrimidinone scaffold with a tertiary or quaternary amine side group. A series of molecules were evaluated for preliminary pharmacological activity on rat ileum out of which three molecules found active.