PubMed · 6990852
Scarlet red-impregnated gauze is commonly used by plastic surgeons on granulating surfaces to promote epithelialization. Its mode of action is not fully understood.
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P B Fodor. 1980. Scarlet red.. https://pubmed.ncbi.nlm.nih.gov/6990852/
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Singlet oxygen generation from laser-excited photosensitive dyes was measured directly using a sensitive near-infrared emission spectrometer to monitor the O2(1 delta g)-->O2(3 sigma -g) transition at 1268 nm. The emission intensity was proportional to both the laser power and the concentration of the dyes. The singlet oxygen producing ability of the dyes was compared with that of eosin YS as a standard in methanol. The relative efficiencies of singlet oxygen generation were determined for rose bengal, erythrosine B, phloxine B and eosin YS as 2.39, 1.73, 1.38, 1.00, respectively, while uranine showed no emission in this spectral region. Using rose bengal, erythrosine B, phloxine B and eosin YS, the efficiency of singlet oxygen generation correlated with the photobleaching reaction rate of azo-dyes by these dyes, suggesting singlet oxygen to be a species responsible for causing the photobleaching of azo-dyes. The halogen substituent effect on the efficiency of singlet oxygen generation from laser-excited photosensitive dyes was also examined systematically.
Lignin peroxidase (LiP) is an extracellular enzyme produced by the lignin-degrading fungus Phanerochaete chrysosporium and is involved in azo dye degradation by this organism. In this study, LiP oxidation of the sulfonated azo dyes 4-(4'-sulfophenylazo)-2,6- dimethylphenol (I), Orange II [1-(4'-sulfophenylazo)-2-naphthol] (II), a dimethyl analog of Orange II [1-(2',6'-dimethyl-4'-sulfophenylazo)-2-naphthol] (III), and 4-(4'-sulfonamidophenylazo)-2,6-dimehtylphenol (IV) was examined. Azo dye I was oxidized to 2,6-dimethyl-1,4-benzoquinone and 4-sulfophenyl hydroperoxide. Orange II (II) was oxidized to 1,2-naphthoquinone and 4-sulfophenyl hydroperoxide. The dimethyl analog of Orange II (III) was oxidized to 1,2-naphthoquinone and 2,6-dimethyl-4-sulfophenyl hydroperoxide. Azo dye IV was oxidized predominantly to 2,6-dimethyl-1,4-benzoquinone and another product, tentatively characterized as 4-sulfonamidophenyl hydroperoxide. In the 18O-labeling studies with 18O2, oxygen incorporation into the phenyl hydroperoxides from the oxidation of I and III was observed. A mechanism for azo dye degradation consistent with product identification and the 18O-labeling studies is proposed. Two successive one-electron oxidations of the phenolic ring of an azo dye by the H2O2-oxidized forms of LiP produces a carbonium ion. Then water attacks the phenolic carbon bearing the azo linkage, producing an unstable hydroxy intermediate which breaks down to yield a quinone and a sulfo- or sulfonamidophenyldiazene. The phenyldiazene is oxidized by O2 to generate the corresponding phenyldiazene radical, which eliminates N2 to yield a sulfo- or sulfonamidophenyl radical. O2 scavenges the latter to yield the corresponding hydroperoxide.(ABSTRACT TRUNCATED AT 250 WORDS)