Phenoxazin-3-one

Substituted phenoxazin-3-one pigments impart the very stable bright orange-red colour to the conspicuous bracket shaped fruit bodies of the wood-rotting fungi Pycnoporus cinnabarinus, P, sanguineus and P. coccineus (Table 45). 

The elucidation of the structure of cinnabarin (477) involved an interesting series of classical experiments carried out contemporaneously in the laboratories of Gripenberg in Finland and Cavill in Australia. After a considerable amount of initial speculation 159,163, 308, 326) regarding the nature and location of the substituents in the distinctive phenoxazinr3-one nucleus, the correct structure (477) was eventually fonnulated (160, 161, 309) and subsequently confirmed by chemical methods (161,162, 309, 312, 328). 

The suggestion, tentatively made, that the phenoxazinones may ultimately prove of value to the taxonomy of Pycnoporus (314) has not been borne out by subsequent studies. Thus, the pigments (477), (478), and (479), along with several unidentified phenoxazinones, are present 

The relationship, if any, between the known phenoxazinone pigments, Zopf s xanthotrametin 731) and Lemberg s polystictinin 451) remains obscure. 

The orange phenoxazin-3-one (481) and its yellow-brown amino derivative (480) have recently been isolated from cultures of the agaric, Calocybe gambosa 560). 

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Phenoxazin-3-ones synthesis, 3, 1034 Phehprocoumon H NMl 3, 582 Phensuximide as anticonvulsant, 1, 166 Phentolamine... 

Resorufin (7-hydroxy-3H-phenoxazine-3-one Na salt) [635-78-9] M 213.2, pK 6.93, pKj 9.26, pK l0.0. Washed with water and recrystd from EtOH several times. 

Fig. 5 Example of steric CoMFA contour map results using APO (2-amino-3H-phenoxazin-3-one) for visualization near green area greater toxicity is correlated with more bulky groups and near yellow area with the less bulky group. 

Dactinomycin Dactinomycin, 2-amino-l,9-bis-(2,9-diisopropyl-6,10,13-trimethyl-l,4,8,ll,14-pentaoxo-7-oxa-3,10,13-17a-tetraaza-5-bicyclo[14.3.0]nonadecylcarbamoyl)-4,6-dimethyl-3//-phenoxazin-3-one (30.3.1), is one of the first antibiotics isolated from a liquid culture of microorganisms of the family Streptomyces parvulus [80-87]. It is a chromonopeptide with a phenoxazine ring and two cyclic polypeptides joined to the carboxyl group at position 2 and 9 of the phenoxazine ring. 

Phenoxazin-3-ones and phenothiazin-3-ones can be prepared by condensation of 2-aminophenols or -thiols with quinones. Alizarin Green G (61), for example, is obtained from (59) and (60). Similarly, 2-aminothiophenols and 6-chloro-2-methoxy-l,4-benzoquinone (62) afford phenothiazin-3-ones (63). 

Actinomycin D has been clinically used for the treatment of many cancers and is known to be a DNA intercalator. The structure of actinomycin D is based on a phenoxazine ring bound to two cyclic pentapeptides [33]. The presence of the phenoxazine ring in the structure of actinomycin D suggests that phenoxazine derivatives may possess anticancer activity. Phenoxazine derivatives are known to be effective multidrug resistance (MDR) modulators in cancer cells [34], potent inhibitors of Akt signaling in cells [35], inhibitors of human plasma cholinesterase [36], and photo-chemotherapeutic agents in cancer cells [37]. Recent studies also show that the relatively water-soluble phenox-azines, such as 2-amino-4,4a-dihydro-4a,7-dimethyl-2H-phenoxazine-3-one and 2-aminophenoxazine-3-one, exert antitumor effects on various cancer cells in vitro and in vivo. [38]. We have investigated 24 phenoxazines [23,39] (Fig. 4). 

Phenoxazine and 3-acetoxyphenoxazine, as well as their 10-acetyl derivatives, when oxidized with nitrous acid at 5°, are converted into 3H-phenoxazin-3-ones.40... 

Reductive acetylation of various 3//-phenoxazin-3-ones has been shown to yield the corresponding 3-acetoxyphenoxazines.40... 

Tecoma stans,93 have been shown to catalyze the condensation of o-aminophenol to 2-amino-3i/-phenoxazin-3-one (52, R = H) to which the name questiomycin A has been given by Anzai et al.9i This compound has been isolated also from Streptomyces fungicidicus,9 and, along with 2-acetylamino-3i/-phenoxazin-3-one (52, R = COCH3), from members of the actinomycete genus Waksmania.96... 

The change in color from various shades of red to yellow, which accompanies the reduction of substituted 3iZ-phenoxazin-3-ones, has made them suitable as bromometric and stannometric redox indicators111-113 RuziCka114 reported also the microdetermination of compounds containing SH groups with such derivatives. Phenoxazine has been described as a stabilizer for polymerizable vinylpyridines115... 

Polarographic studies of dyes have been described Pamfilov et al. reported the polarography of Methylene Blue and Thionine at a dropping mercury electrode, and other Soviet workers have reported a polarographic study of 3i/-phenoxazin-3-one and its benzo derivatives. 

A flash-photolytic study of phenoxazine has been reported.Three transient species were observed the first triplet state, 253, and 248. The results are consistent with the formation of 248 in a biphotonic process involving the triplet. In the presence of oxygen, neither the triplet nor 248 was observed continuous-irradiation experiments indicated that probably 253 reacts with oxygen, via unstable hydroperoxide intermediates, to give, as stable photooxidation product, 3i/-phenoxazin-3-one. 

Uptake kinetics with oat had to be performed in presence of antibiotics, because the benzoxazolin-2(3//)-one was converted to orange-red compounds, due to microbial activity. One compound was identified as 2-amino-5//-phenoxazin-3-one [180], which is known to appear within 10 days in nonsterile soil after incubation with DIBOA [181]. Microorganisms degrade BOA to 2-aminophenol, that reacts subsequently without further enzymatic catalysis resulting in 2-amino-i//-phenoxazin-3-one [182-185]. Acinetobacter calcoacetius was identified as an organism responsible for 2-aminophenol production [183]. In antibiotic-... 

ReSOmfin (7-hydroxy-3ff-phenoxazin-3-one Na salt) [34994-50-8] M 252.2, decomp on heating, pK 5,8 (H2O), 6.10 (50% aqueous MeOH). The free acid is purified by dissolving it in cone H2SO4 which on dilution precipitates resorufin and is filtered off, washed well with hot H2O and dried. [Eichler J Prakt Chem 139 113 1934 Detailed UV and IR studies were reported by Musso Mattheis Chem Ber 90 1814 1957]. [pKa Musso Rathjen Chem Ber 92 751 1959, Beilstein 27 IV 2263.]... 

The irradiation of the phenoxazin-3-one dye, resazurin (21), in the presence of tertiary amines results in its efficient deoxygenation via the triplet state, forming the dye resorufin (22). The radiolysis/photolysis of aqueous solutions of pyrimidines produces radicals which are the result, in general, of 1-electron reduction involving hydrated electrons. The structures of the radicals were assigned on the basis of their by EPR spectra. The study included 2-hydroxypyrimidine... 

Heating benzoxazinone under the same conditions leads to 4,5,6-tetrafluoro-3f/-pyrido[3,2,l-k]phenoxazin-3-one (97ZOR1418) (Scheme 160). 

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