Molecular connectivity study of muscarinic receptor affinity of acetylcholine antagonists

A correlation between three molecular connectivity indexes and the muscarinic receptor affinity of 104 acetylcholine antagonists was found. Analysis of structure from these indexes reveals not only the importance of the onium and the bulky portions of the molecule but also their virtual independence of each other on the affinity. Analysis of the onium group portion of the molecules indicates that its contribution to the experimental affinity is virtually constant through a variety of structural variations. The influence of the bulky side chains, in contrast, is quite structure dependent. The equation relating connectivity indexes to muscarinic affinity of antagonists is capable of predicting the affinity of other antagonists as well as a number of agonist molecules.