PURIFICATION, CHARACTERIZATION AND ANALYSIS OF MELANIN EXTRACTED FROMTUBER MELANOSPORUM VITT

A new method for the purification of melanin extracted from Tuber mela nosporum Vitt. with KOH under nitrogen was developed. The physical and chemical properties of the resulting dark pigment were determined, in cluding its elemental composition and ultraviolet (UV) and infrared (I R) spectra. The results of this study were calibrated using data obtai ned with synthetic dihydroxyphenylalanine (DOPA) melanin and indicate that (1) purification with chloroform gave the best results, as shown by elemental and infrared analysis; and (2) the synthetic and natural melanins have the same physical and chemical properties, with the same percentage of nitrogen, the same functional groups and the same degre e of polymerisation. However, they showed large differences in: (1) th e time necessary to become decolorised by oxidizing agents (NaOCl and H2O2); (2) the slope of log absorbance vs wavelength. These results an d data found in the literature lead to a proposal that melanin of T. m elanosporum is derived from a new nitrogen precursor. Copyright (C) 19 96 Elsevier Science Ltd.