Investigations on organic fungicides. IX. The antagonistic action of certain imidazole derivatives and of [alpha]-keto acids on the fungitoxicity of dimethyldithiocarbamates

Abstract

1. 1. Apart from -histidine a variety of other imidazole derivatives is able to antagonize the inhibiting action of sodium dimethyl dithiocarbamate (NaDDC) on spore germination of moulds in the first zone of inhibition.

2. 2. - and -histidine, -histidinol and imidazole-4-carboxylic acid are of about equal activity. Imidazole-4-pyruvic acid is ca. ten times more effective, while the other compounds tested are less effective than histidine.

3. 3. By the use of a histidine-effect mutant of Aspergillus niger it was proved that the antagonistic activity of the different compounds is not due to conversion into -histidine.

4. 4. In addition it was found for A. niger that a-keto acids are very active NaDDC antagonists in the first zone of inhibition, these compounds being totally ineffective for the other three test moulds.

5. 5. The general antagonizing activity of imidazole derivatives suggests that they prevent NaDDC from interaction with some essential enzyme system.