Phenoxazinone

Snznki H, Y Fnrnsho, T Higashi, Y Ohnishi, S Horinonchi (2006a) A novel o-aminophenol oxidase responsible for formation of the phenoxazinone chromophore of grixazone. J Biol Chem 281 824-833. 

Normal copper enzymes Phenoxazinone synthase Superoxide dismutase... 

Phenol, see Aminocarb. Benzene, Bromobenzene, Carbaryl, Chlorobenzene, 2-Chlorobiphenvl. 4 Chlorobiphenvl. 1,4-Dichlorobenzene, Hexachlorobenzene, Hydroquinone, 4-Methylphenol, Naphthalene, Pentachlorobenzene, Toluene, 1,2,3-Trichlorobenzene Phenoxazinone, see Phosalone Phenoxyacetic acid, see 2,4-D... 

Soil. Ambrosi et al. (1977a) studied the persistence and metabolism of phosalone in both moist and flooded Matapeake loam and Monmouth fine sandy loam. Phosalone rapidly degraded (half-life 3-7 d) but mineralization to carbon dioxide accounted for only 10% of the loss. The primary degradative pathway proceeded by oxidation of phosalone to phosalone oxon. Subsequent cleavage of the 0,0-diethyl methyl phosphorodithioate linkage gave 6-chloro-2-benzoxazolinone. Although 2-amino-5-chlorophenol was not detected in this study, they postulated that the condensation of this compound yielded phenoxazinone. 

Aromatization can also be accomplished by oxidative cascade reactions-a strategy often utilized by natural product biosynthesis [33]. For example, the phenoxazinone chromophore of actinomycin was proposed to be generated by a six-electron oxidation of aminophenols catalyzed by a copper-containing oxidase (Scheme 7.8) [34]. 

Other Copper Oxidases. A number of additional multicopper oxidases have been detected [22], including phenoxazinone synthase (Table 1). This enzyme catalyzes the overall six-electron oxidative coupling of 2-aminophenols to form 1-aminophenoxazinone, the final step in the bacterial (Streptomyces) biosynthesis of the antineoplastic agent actinomycin. 

Despite the ionic reactions, other reactions (presented in Scheme 44) show that free-radical mechanisms can also take place. Catalyzed by ebselen, TBHP oxidation of alkylarenes to alkyl aryl ketones (141) [240], anthracene to anthraquinone (142), 1,4-dimethoxyarenes to 1,4-quinones (e.g., menadione 143) [244], and oxidative coupling of 2-aminophenol to phenoxazinone (144) [245] gave results similar to these when one-electron oxidants such as Ce(IV), Ag(II), or Mn(III) were the reagents. Moreover, oxidation of azine derived from 2-acetylpyridine gave a mixture of ketone (145) and condensed triazole (146) [240], The same result was found when cerium ammonium nitrate was used as the reagent. This suggests that the... 

At present, many coordination compounds, which contain ligands capable of participating in easy and reversible one-electron redox processes, are known. Nitroxyl radicals, spatially hindered o-quinones, quinoneimines, and phenoxazinone systems are examples of such ligands. 

Figure 3.13 Two-step grafting process in order to construct a sensor for the detection of volatile organic compounds based on the well-known solvatochromic fluorescent phenoxazinone dyes. Hydrophobizing of the surface of MCM-41 with silazanes leads to better performance of this sensor.

Figure 19.2 Schematic model of the biomimetic material Ml for the sensing of long-chain carboxy-lates. Hydrophobic forces bind the tail to the wall, enabling hydrogen bonding interactions of the analyte s head group with the urea group of the phenoxazinone dye. The result is a color and fluorescence modulation. Lower left inactive nonhydrophobized material M2. Lower right inactive molecular probe PI.

Whereas, Acinetobacter calcoaceticus strains (Waksmania aerata and Pseudomonas iodina as well) are able to cleave benzoxazolinone to 2-aminophenol resulting in phenoxazinone (Fig. 4.6), bacteria belonging to this group are unable to metabolize glucose carbamate and BOA-6-OH25,26 (Burziak et al. unpublished). 

Gerber, N. N. and LeChevalier, M. P. 1964. Phenazines and phenoxazinones from Waksmania aerata sp. nov. and Pseudomonas iodina. Biochemistry 3, 598-602... 

Cyclic iV-quinonylenaminones have been treated with trifluoroacetic acid/trifluoroace-tic anhydride in order to obtain cyclization to carbazole derivatives. However, the result was a nucleophilic ( ) attack by trifluoroacetate at the enaminone a-methylene group. Cyclization gave a phenoxazinone derivative49 (equation 31). By intramolecular acylation 4-quinolones are also available50 (equation 32). 

As expected, the ascorbate oxidases are very closely related to each other. The bacterial proteins phenoxazinone synthase and the copper resistance gene product from P. syringae are very distant from the other proteins included in Table V. The rape BplO gene product exhibits significant similarity to ascorbate oxidase (about 72% differences). 

Phenoxazinone production was as well observed in incubation media of Secale cereale, but not in such of Vida faba and Triticum aestivum [180]. The compounds can be detected is well in incubation media of several dicotyledonous species [187]. Since surface sterilization of oat caryopses with NaOCl did not prevent phenoxazinone production, it is possible that the responsible microorganism(s) are located within the caryopses. Phenoxazinone itself has an inhibitory effect on oat radicle elongation, probably caused by intercalation of the phenoxazinone ring system to DNA, as it is known from the phenoxazinone ring system of the transcription inhibitor actinomycin D, an antibiotic produced by Strepto-myces species. 

Nevertheless, growth inhibition was less in presence of 1 mM BOA, when phenoxazinone production was not suppressed by addition of canamycin, penicillin and streptomycin to the incubation media [180]. Furthermore, phenoxazinones are rather hydrophobic compounds, which precipitate in aqueous solution and they may also be absorbed by soil particles under natural conditions. 

Taken into account that Secale cereale, for instance, exudes DIBOA, which is converted to BOA, root colonizing bacteria may perform 2-aminophenol production, resulting in phenoxazinones, compounds that probably influence the species composition of micro-organisms within the rhizosphere. On the other hand, hydroxamic acid free species coexisting with rye or wheat can have an advantage when 2-aminophenol producing... 

The phenoxazinone ring system of the actinomycins (19 ) is apparently formed from kynurenine and 3-oxykynurenine with methylation taking place at a late stage 73. Reports on amino acid variation and the mechanism of biosynthesis of the D-amino acids present in the side chains continue to appear 71t>75,76 >77>78,... 

C Eggert, U Temp, JFD Dean, K-EL Eriksson. Laccase-mediated formation of the phenoxazinone derivative, cinnabarinic acid. EEBS Lett 376 202-206, 1995. 

S Christen, P Southwell-Keely, R Stocker. Oxidation of 3-hydroxyanthranUic acid to the Phenoxazinone cinnabarinic acid by peroxyl radicals and by compound 1 of peroxidases or catalase. Biochemistry 31 8090-8097, 1992. 

Jones, G. and D.A. Hopwood (1984). Molecular cloning and expression of the phenoxazinone synthase gene from Streptomyces antibioticus. J. Biol. Chem. 259 2703-2714. 

---