THE INHIBITION OF CHOLINESTERASE BY AROMATIC AMINO ALCOHOLS OF THE TYPE Ar-CHOHCH₂NR₂

¹ From the Division of Physiology, National Institute of Health, Bethesda, Maryland

Phenanthrene amino alcohols were found to be very effective inhibitors of the cholinesterase of human blood plasma. The inhibition of the enzyme is related to the size of the dialkylamino group, passing through a maximum with the dipropylamino derivative in each of four homologous series. The inhibition of the plasma enzyme is decreased by hydrogenation, chlorination or hydroxylation of the phenanthrene nucleus, by replacement of the alcoholic hydroxyl group or by shifting the alkamine side chain from the 9 to the 3 or to the 2 position of the phenanthrene nucleus. Propanolamino compounds are more effective inhibitors of the plasma enzyme than their ethanolamino anologs.

Much higher concentrations of the phenanthrene amino alcohols are required to inhibit the red cell enzyme than the plasma enzyme. This offers a possible means of identifying or separating the two types of enzymic activity. Chemical changes that increase the inhibition of the plasma enzyme decrease the inhibition of the red cell enzyme.

Neither antimalarial activity in the chick nor the dose tolerated by the chick are correlated with the inhibition of cholinesterase by the phenanthrene amino alcohols.