SYNTHESIS AND STUDY OF PYRIDYLALANINE N-OXIDES

The three pyridylalanine N-oxides, β-{2-, 3-, or 4-pyridyl 1-oxide)-DL-alanine, have been synthesized, and their biological activities in Escherichia coli 9723 and Lactobacillus arabinosus 17-o have been determined. 4-Pyridylalanine N-oxide inhibits growth of E. coli at concentrations of 30 µg/ml and higher. The 2- and 3-pyridylalanine N-oxides are less effective inhibitors in this organism; the toxieities of all three N-oxides are reversed by supplements of phenylalanine or tyrosine. Evidence is given for the enzymatic reduction of the pyridylalanine N-oxides to the corresponding pyridylalanines in E. coli and for the probability that the toxicity of 4-pyridylulanine N-oxide in this organism is due to the formation of the more toxic 4-pyridylalanine. The pyridylalanine N-oxides are inhibitory to L. arabinosus only at very high concentrations; the organism does not reduce these compounds to the pyridylalanines. © 1968, American Chemical Society. All rights reserved.