Quinine, quinidine and quinacrine showed a slight inhibitory effect on ChE's in the liver and the brain of the cat and on amine oxidases of the hog kidney. The affinity of quinine-group compounds to ChE's is at the highest on the ACNE of the liver and at the lowest on the specific ChE of the brain. Seventy % of the activity of MAO was inhibited by 10-2M quinine and 77% of the activity of DAO was inhibited by 10-3M quinacrine, 50% by 10-2M quinine and quinidine. The therapeutical dosage of quinine sulfate may have no effect on ChE's and amine oxidases in aa body. The therapeutical dosage of quinidine sulfate may inhibit about 50% of the ACNE activity of the liver, but may have no effect on other ChE's and amine oxidases.
