Interference of the Reduction of p-Nitrobenzoate in E. Coli by Nitrofurantoin

Abstract

1. The enzymic reduction of p-nitrobenzoate into p-aminobenzoate by E. coli B was investigated in vitro with either NADH or NADPH as hydrogen donor.

2. For the NADH-mediated reaction a sulphydryl compound (L-cysteine) is required. In contrast, in the NADPH-mediated reaction the presence of L-cysteine is not obligatory, but, if present, considerably stimulates nitroreductase activity.

3. Addition of nitrofurantoin strongly inhibits the NADH-mediated nitroreduction, non-competitively. No inhibition was demonstrated in the presence of NADPH, probably because of rapid reduction of the inhibitor.

4. Reduction of nitrofurantoin was 15–20 times slower with NADH as hydrogen donor. The influence of NADH and NADPH on the reduction and degradation of nitrofurantoin was studied spectrophotometrically.