Purification, Structure And Anti-radiation Activity Of Melanin From Lachnum YM404

In this paper, the optimum fermentation conditions, the extraction ofintracellular melanin, structure, anti-radiation activity and the hyperchromic effect ofmelanin from Lachnum YM404were studied. The research contents and results are asfollows:Fermentation conditions of Lachnum YM404were determined by single factorexperiments as follows: maltose25g/L, yeast extract6g/L and L-dopa1.25mmol/L withshaking speed200r/min at26°C for10d. Under this condition, the biomass andmelanin yield of YM404was14.6%and22.7%, respectively, which was higherthan those of condition without optimization.On the basis of single factor experiments, the optimum ultrasound-assistedextraction conditions of Lachnum YM404intracellular melanin(LIM404-2) usingBox–Behnken design were as follows: NaOH concentration1.5mol·L1, ultrasonicpower82W, extraction temperature75°C, extraction time33min. And the optimumenzymatic hydrolysis conditions of Lachnum YM404intracellularmelanin(LIM404-3) were as follows: neutral protease4%, the liquid-solid ratio20:1, extraction temperature37°C, extraction time4h. The yield of LIM404-2was12.50%,5.04%higher than that of LIM404-1(which extraction by alkali extractionand acid precipitation), and12.25%higher than that of LIM404-3. LIM404-3revealed the most complete structure and the higest total antioxidant capacity.Under the optimal fermetation and extraction condition,3.45g/L extracellularmelanin mixture (LEM404) was produced by Lachnum YM404. Five kinds ofhomogeneous component were fractionated by Sephadex G-15column and LEM404-awas the main component with molecular weight of432.18. Based on elemental analysisand mass spectrometry, LEM404-a was proved as phaeomelanin, and the molecularformula (C22H12N2O4S2) was concluded. Infrared spectroscopy of LEM404-a indicatedthat it had typical indole structure of melanin. The results of Py-GC-MS and1H NMRindicated that the basic skeleton of LEM404-a was composed of pyrrole and benzene. Thestructural formula of LEM404-a were concluded as LEM404-a could significantly increase the survival rates of Escherichia coli,Staphylococcus aureus and Saccharomyces cerevisiae under UV radiation. Anti-radiationexperiments in mice showed that the skin manifestations in mice of low radiation doseexperimental group (LEG) were similar to those in blank control group (BCG). Comparedwith the control groups (LCG and HCG), SOD and GSH-PX activities in mice ofexperiment groups (LEG and HEG) were improved significantly while MDA content weredecreased significantly, indicating that LEM404-a had strong anti-ultraviolet radiationactivity.Six kinds of hair dyes were prepared, and the dyeing effect were investgated. Theresult suggested that the melanin hair dye with LEM404-a had more significant dyeingeffect than others as well as less toxicity. However, single LEM404-a did not exhibithyperchromic effect on white hair.