Chemical and Biological Studies on 1,2-Dihydro-s-triazines. IV. Activity in Pteroylglutamic Acid-Streptococcus faecaelis No. 8043 Systems

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Abstract
A series of 71 1, 2-dihydro-s-triazines have been studied in S. faecalis No. 8043-pteroylglutamic acid assay systems. The active derivatives exhibit noncompetitive inhibition over a wide range of concns. of PGA and differ from 4-aminopteroyl-glutamic acid in that inhibition is not relieved by adenine or guanine and is irreversible with pteroylglutamic acid. Differences in microbiological activity could be correlated with certain variations in structure and substitution in the molecule with the series. Max. activity is obtained with 2,2-dimethyl substitution in the triazine ring together with para- and meta-halogen substituents in the phenyl ring. The inhibitory effect of these compounds on S. faecalis No. 8043 is reversed by appropriate concns. of dihydropteroylglutamic acid, N10-formyl-pteroylglutamic acid, synthetic and natural citrovorum factor and thymine, suggesting that these compounds interfere with the conversion of pteroylglutamic acid to citrovorum factor.