THE EFFECT OF PROPAMIDINE AND CERTAIN OTHER DIAMIDINES ON THE OXIDATION OF VARIOUS SUBSTRATES BY E. COLI

¹ From the Department of Physiology and Pharmacology, Duke University School of Medicine, Durham, North Carolina

1. Propamidine inhibits the oxidation of l-proline and of both isomers of alanine by E. coli. Under the same conditions it accelerates the oxidation of serine and asparagine although higher concentrations inhibit. The oxidation of glycine is inhibited but only by relatively high concentrations.

2. The action of the drug requires an incubation period of at least 2 hours. The presence of glucose during this incubation period increases the subsequent effect of the drug.

3. The drug concentration relative to the number of bacteria present determines its effect on the oxidation of the amino acids.

4. The oxidation of glucose, pyruvic acid and succinate is not affected by concentrations which inhibit or accelerate the oxidation of the amino acids.

5. Propamidine is much more effective at pH 7.8 than at pH 6.7.

6. In comparable concentrations pentamidine and stilbamidine are only slightly less active than propamidine but phenamidine is almost entirely inactive.