Molecular Modification And Biological Activities Of Melanin Produced By Lachnum Sp.

An intracellular melanin (LIM205) was isolated from Lachnum YM205 mycelia by alkaline extraction and acid precipitation. LIM205, the main homogeneous component, was fractionated on a Sephadex G-15 column. The molecular fomula and structure of LIM205 were determined through elemental analysis, mass spectrometry, IR, Pyrolysis/GC/MS and NMR.By using carboxymethylation and sulfation to modify the homogeneous component melanin (LIM205) from Lachnum sp. respectively, a water-soluble melanin carboxymethylate (CLIM205) and a melanin sulfate (SLIM205) were obtained, and the modifications were successfully verified by UV and FT-IR spectra. LIM205 was insoluble in water at the temperature of 30?, and the water solubility of CLIM205 and SLIM205 were 3.75 g,2.06 g, respectively. The abilities of LIM205, CLIM205, SLIM205 to scavenge OH, O2-·, DPPH and to chelate Fe2+were tested, and the relationship of their antioxidant capacity was CLIM205> SLIM205> LIM205. At the same dosage, the antioxidant activities of SLIM205 was increased 3.46%,6.87%, 4.47%,16.5% than that of LIM205, and CLM205 was also increased 16.13%,30.44%, 17.32% and 28.90%. These results suggested that LIM205 was carboxymethylated and sulfated to prepare an water soluble melanin derivatives, the antioxidant activity of water soluble derivatives were more stronger than that of insoluble melain, which indicated that CLIM205 and SLIM205 can be used as new antioxidant components in medicine and health products.The efficacy of CLIM205 and LIM205 to reduce tissue lead concentration was evaluated experimentally in lead poisoned mice. The results showed that CLIM205 reduced the tissues lead concentration, enhanced lead excretion, elevated immune organ indices, and reversed lead-induced alterations in SOD, GSH-PX and MDA contents in mice, significantly. In addition, the efficacy of CLIM205 was stronger than that of LIM205. These results authenticated the potential therapeutic ability of LIM205 and CLIM205 to reduce tissues lead concentration in mice.We evaluated the immunological efficacy of LIM205 and CLIM205 in modle mice, respectively, and hypoimmune model mice induced by cyclophosphamide. Different dosages of LIM205 and CLIM205 were given to mice once daily for 30 consecutive days.. The results of mice experiment showed that LIM205 could significantly increase the spleen, thymus indexes, phagocytic rate, phagocytic index, the amount of hemoiytic antibody and stimulate both the specific and non-specific immune function in model mice, and reversed lead-induced alterations in SOD, GSH-PX and MDA contents in mice, The immunological efficacy of CLIM205 was stronger than that of LIM205.