Abstract
The present investigation was undertaken to demonstrate the fungicidal mechanism, mainly the inhibition to the respiratory enzymes of Piricularia oryzae, of 1-(3, 4-dichlorophenyl)-2-acetylhydrazine (I) as an example of β-acylphenylhydrazine derivatives.
Compound I inhibited only the increase of oxygen uptake by intact mycelium in the following substrates; glutamate, fumarate, succinate and glucose. In contrast to these of intact mycelium, the respiration of spores was not affected by I.
The locus of inhibition of I in the electron transfer system is the site of the SC-factor, and this site coincides with the inhibition site of phenylhydrazines described by Ozawa and Asami. The inhibition patterns to the succinate oxidase system, especially succinate-cytochrome c reductase, and to glutamate decarboxylase support the assumption that compound I shows marked inhibition by the hydrazine decomposed in the mycelium of P. oryzae.
Compound I also inhibited moderately the rate of oxidation of NADH2 in transketolase system of the hexose monophosphate shunt.
