Enzyme Inhibiting Action of Tetrahydroaminoacridine and its Structural Fragments

Abstract

Abstract Tetrahydro-5-aminoacridine and four compounds representing its structural fragments have been compared as inhibitors of acetylcholinesterase and of monoamine oxidase. The entire structure of tetrahydro-5-aminoacridine appears to be essential for optimal inhibition of the esterase, less than 10−6 m concentration showing a 50 per cent inhibition of the enzyme, with the inhibition constant Ki as 1 × 10−4. For optimum inhibition of monoamine oxidase, the 4-aminoquinoline part of the acridine molecule appears to be a structural requirement. 4-Arninoquinoline shows a stronger monoamine oxidase inhibition than any known therapeutically used inhibitor. It gives a 50 per cent inhibition of the oxidase in 10−6 m concentration, with ki as 1.1 × 10−5.