Iodinin

Reference has already been made to iodinin (120) (1,6-dihydroxyphenazine 5,10-dioxide), the violet pigment produced by the bacterium Chromobacterium iodinium. Iodinin... 

Phenazines — This large class of compounds includes more than 6,000 natural and synthetic representatives. Natural phenazines are secondary metabolites of certain soil and marine microorganisms. The main phenazine producers are Pseudomonas and Streptomyces species. Pseudomonas strains produce the most simple phenazines tubermycin B (phenazine-1-carboxylic acid), chlororaphine, pyocyanin, and iodinine. Pyocyanin is a blue pigment while chlororaphine is green both are produced by Pseudomonas aeruginosa. They can be seen in infected wounds of animal and human skins. Iodinine is a purple phenazine produced by Pseudomonas aureofaciens. 

Antagonists of vitamin K substances include dicoumarol, sulfonamides, antibiotics, a-tocopherol quinone, dihydroxysteanc acid glycide, salicylates, iodinin, warfarin. Synergists include ascorbic acid, somatotropinn (growth hormone), and vitamins A and E. 

Phenazines.—Results on the biosynthesis of microbial phenazines from shikimic acid (previously published in preliminary form cf. Vol. 5, p. 44 and Vol. 7, p. 27) are now available in full papers.53 Additional results are that 2,3-dihydro-3-hydroxyanthranilic acid (140) was not a precursor for iodinin (141), nor was... 

The accumulation of phenazine-1,6-dicarboxylic acid (154) by mutants of Pseudomonas phenazinium148 which normally produce hydroxy-phenazine derivatives supports a role for (154) in phenazine biosynthesis. In further studies143 with Ps. phenazinium the sequence of hydroxylative steps leading to the various phenazines has been deduced143 148 to be that illustrated in Scheme 15 the biosynthesis deduced for iodinin (156) is in agreement with earlier conclusions about its formation in cultures of another organism (Brevibacterium iodinum ).146... 

Iodinin, an antibiotic pigment isolated from Chromobacterium iodinum, has been shown88 to be 1,5-dihydroxyphenazine di-A-oxide (63), which probably arises biosynthetically by oxidative coupling of two molecules of anthranilic aeid.88a... 

Shikimic acid, an intermediate in the biosynthesis of phenazine derivatives (e.g., iodinine, pyocyanin) can act as the sole carbon source in the formation of the phenazine skeleton. 

The acidophilic bacterium Pseudomonasphenazinium has been observed to produce the water-insoluble purple pigment iodinine (phenazine-1,6-diol 5,10-dioxide). 

Phenazines.—Shikimic acid (134) is clearly implicated as a precursor for microbial phenazines, e.g. iodinin (135), and it can act as the sole source of the carbon skeleton. Essential proof that two molecules of shikimic acid are involved in phenazine biosynthesis was provided when it was shown that on incorporation of DL-[1,6- C2, 2- H]shikimic acid [as (134)] into iodinin (135) in Brevibacterium iodinum, some (7.5%) of the molecules of (135) produced were dideuteriated. [The shikimic acid was incorporated with the usual high efficiency (similar values for and H) and the deuterium label was confined to the expected positions (see below).]... 

It follows from this result and the C labelling studies " that phenazine biosynthesis proceeds from two shikimic acid units linked as in (136) or (137). By determining that the sites of deuterium labelling in the iodinin (135) derived from... 

H]shikimic acid were exclusively at C-2 and C-7, it followed that the biosynthesis of iodinin (135), and most probably other phenazines, was according to pattern (136) and not pattern (137). This accords with the structures of other naturally occurring phenazines like the griseoluteins, e.g. griseolutein A (140). 

Purify iodinin through a column of silica gel and elute with Me2CO/CHCl3, then recrystallise it from CHCI3 to give purple crystals with a copper-coloured luster. [Clemo Dalgleish J Chem Soc 1481 1950, Gerber Lechevalier Biochemistry 3 598 1964, Beilstein 23 III/IV 3227,]... 

A striking and consistent feature of the glutamine and ammonium sulphate incorporations into iodinin (121) was that the... 

Zasshi 81, 515 (I960). C.A. 56, 470a (1962). Biosynthetic studies on incorporation of shikimic acid, q.v. into iodinin ... 

Administration of the same precursor to Brevibacterium iodinum gave radioactive iodinin (178). This material was subjected to the usual degradation (Scheme 19). In accord with the labelling pattern observed in phenazine-1-carboxylic acid (177), 100% of the activity appeared in the pyrazine (180) but strangely 12% also appeared in the carbon dioxide. 

Another group found different results for the incorporation of d-[6- C]-shikimic acid into iodinin (178), but further study of iodinin derived from D-[l- C]shikimic acid revealed that the degradative procedure used by both... 

The results obtained for iodinin (178) with and D-[l,6,7- C3]shikimic acids and for phenazine-1-carboxylic acid (177) with and DL-[l,6- C2]shikimic acids are now in agreement with... 

Hydroxyphenazine-l-carboxylic acid was shown to be present in cultures producing iodinin (178) (by dilution after feeding [6- C]shikimic acid). This strengthens its assigned position as an intermediate in iodinin biosynthesis. 

Phenazine-l,6-dicarboxylic acid (167) might appear to be the phenazine formed initially by the coupling of two shikimic acid derivatives, but [2,4- H2]-phenazine-l,6-dicarboxylic acid (as 167) was not incorporated into pyocyanin (173) in Ps. aeruginosa, or iodinin (180) in Brevibacterium iodinum Ps. iodina). ... 

Iodinin also showed no incorporation of deuteriated (168), (170), (171), or 1-hydroxyphenazine. On the other hand, the N-oxide (178), which was isolated from B. iodinum, showed efficient incorporation of deuteriated 1-hydroxyphenazine and l-carboxy[6,7,8,9- H4]phenazine (as 170). Further, the latter was incorporated without deuterium loss and thus its conversion into (178) is analogous to its conversion into pyocyanin (173). 

It follows from the above evidence that one of the hydroxy-groups in iodinin (180) is present before formation of the phenazine ring system. Accordingly, a highly efficient incorporation of 6-hydroxy-[7,9- H2]phenazine-l-carboxylic acid (as 179) into iodinin (180) was found. It thus appears probable that B. iodinum converts (170) and (179) by the same or similar enzyme systems into (178) and iodinin (180), respectively, N-oxide formation occurring either before or after hydroxylative decarboxylation. The two acids, (170) and (179), may well arise from the same (non-aromatic) precursor, by alternative aromatization reactions. 

Dihydroxyphenazine and its 5-oxide have been found to serve as iodinin precursors. The former compound is unlikely to be a normal intermediate as it was significantly less efficiently utilized than (179). ... 

Mention was made above that the nature of the shikimic acid derivatives involved in phenazine ring formation was unknown. In addition, little is known of which atoms of shikimic acid correspond to particular atoms in the phenazine nuclei of the various metabolites a degradation of iodinin after incorporation of [l,6- C2]shikimic acid ° was open to at least two interpretations. 

Phenazines.—A study using [6- C]shikimic acid [as (126)] has given results which confirm previous ones " concerning the orientation of shikimic acid (126) units in the bacterial phenazine iodinin (127). 

It has been claimed that dimethyl phenazine-1,6-dicarboxylate (128) is a precursor for 1-carboxyphenazine in Pseudomonas aureofaciens cf. ref. 8. This claim has been disputed careful checking showed that neither (128) nor the corresponding acid (129) was incorporated into phenazines produced by this organism. This has been supported by the results of other workers, who have found that (128) is metabolically inert in P. aureofaciens. Moreover, neither (129) nor (128) was incorporated into phenazines in P. phenazinium. On the other hand, efficient incorporations have been recorded of (129), but not of (128), into iodinin (127) and related phenazines in three actinomycetes, i.e. Streptomyces thioluteus, Microbispora amethystogenes, and M parva ... 

---