The anti-streptococcal action of iodinin. Naphthaquinones and anthraquinones as its main natural antagonists

Abstract

Iodinin is a pigment isolated from Chromobacterium iodinum which inhibits growth of some other bacteria. The substance is a di-N-oxide of a dihydroxyphenazine. It inhibits growth of streptococci partly in 3 × 10-7 M or completely in 1.2 - 2.0 × 10-6 M. Phenazine di-N-oxide is also active but a higher concentration is required. A few extracts from biol. materials (plant, animal, bacterial) are found to annul the action of iodinin, and these probably contain anthraquinone and naphthoquinone derivatives At any rate pure hydroxyanthraquinones and 2-methyl-1,4-naphthoquinone in concentrations of 5 × 10-7 to 5 × 10-6 M antagonize iodinin, the N-oxides being destroyed in the process by reduction. Since this reaction does not occur in vitro, it indicates that the quinones must participate in the metabolism, either by functioning as H transporters or the iodinin may inhibit some system which normally is concerned with quinones.