The effect of flavins and enzyme inhibitors on 4-nitrobenzoic acid reductase and azo reductase of Ascaris lumbricoides var suum.

1. The effects of inhibitors and activators on the azo- and nitro-reductases of Ascaris lumbricoides var suum have been investigated. Both types of reduction were inhibited by FAD, FMN, riboflavin, allopurinol, dicoumarol, 5-nitro-2-furaldehyde, azide and cyanide at concentrations of 1 mM. Neither reaction was inhibited by menadione, nitrofurantoin, SKF 525-A or fluoride. Both reactions were stimulated by addition of hypoxanthine. 2. The enzyme preparation contained no detectable aldehyde oxidase or xanthine oxidase activity. 3. The differences in the effects of flavins and inhibitors on mammalian and nematode azo- and nitro-reductases might have practical significance in the development of anthelmintic synergists.