Abstract
Thiamine phenylhydrazone (N-(1-methyl-2-phenylhydrazono-4-hydroxybutyl)-N-[(2-methyl-4-amino-5-pyrimidinyl)-methyl]-formamide) (I) was shown to be inhibitory to the growth of Lactobacillus fermenti 36 and Kloeckera apiculata IFO 0630. The growth-inhibition of L.fermenti by (I) was recovered competitively and specifically by thiamine, and its inhibition index was 55,000. However, the inhibition of (I) for Kl.apiculata was not recovered by any vitamin. The acid-catalysed cyclization product of (I) ; phenyltriazinothiamine (2-phenyl-4-[(2-methyl-4-amino-5-pyrimidinyl)-methyl]-5-methyl-6-(2-hydroxyethyl)-2,5-dihydro-1,2,4-triazinium chloride HCl) (II) showed the same inhibition activity as (I). Reversible conversion was confirmed by means of either absorption spectra or titration curves between (I) and (II) by changing of pH in its aqueous solution. Growth inhibitory effect of (I) seemed to be due to (II) which was converted form of (I) in broth.
