The effects of a hydroxyl group on some chemical and biological properties of n-pentyl ammonium salts

Abstract The effects of a hydroxyl group on the activity and affinity of compounds related to n-pentyltrimethylammonium have been studied on the guinea-pig ileum, frog rectus, acetylcholinesterase and on partitioning (Rm) and size (φov, Vm). The hydroxyl group lowered affinity in all tests, confirming the importance of hydrophobic forces in binding to receptors. Activity on the ileum was lowered appreciably but on the rectus only slightly. The effects on Rm did not indicate any interactions between hydroxyl, onium group and water but the apparent size of the hydroxyl group (Δφov) depends on the nature of the onium group.