Characterization of melanin pigment produced by <Emphasis Type="Italic">Aspergillus nidulans</Emphasis> |
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Authors: | R C R Gonçalves H C F Lisboa S R Pombeiro-Sponchiado |
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Institution: | 1.Departament of Pharmaceutical Sciences,UFES, Espirito Santo Federal University,Vitória,Brazil;2.Institute of Naturals and Exacts Sciences,UFMT, Mato Grosso Federal University,Rondonopolis,Brazil;3.Department of Biochemistry and Technology Chemistry, Institute of Chemistry, UNESP,S?o Paulo State University,Araraquara,Brazil |
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Abstract: | Although most of the Ascomycetes present DHN-melanin, some reports suggest that A. nidulans does not produce this type of melanin. In this study, we analyzed the pigment extracted from highly melanized strains (MEL1
and MEL2) of Aspergillus nidulans to determine the type of melanin present in this fungus. Our results showed that the pigment produced by MEL1 and MEL2 mutants
possesses physical and chemical properties and UV- and IR-spectra very similar to synthetic DOPA-melanin. The characterization
of this pigment in terms of its degradation products indicated the presence of indolic units, which were also found in synthetic
DOPA-melanin. The analyses of the elemental composition showed that the pigment extracted from these mutants has a high percentage
of nitrogen and, therefore, it cannot be DHN-melanin, which presents only trace of nitrogen. This observation was confirmed
in the test with tricyclazole because this inhibitor of DHN-melanin biosynthesis did not suppress pigment production in the
MEL1 and MEL2 strains. On the other hand, in a medium containing tropolone, an inhibitor of DOPA-melanin biosynthesis, the
dark pigmentation of the colonies was not observed indicating that this compound inhibited melanin production in these strains.
Taken together, the results obtained in this study indicate that melanin produced by these mutants is DOPA type, representing
the first report on characterization of this type of melanin in A. nidulans. |
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