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.