Isolation, purification and physicochemical characterization of melanin from yeast cells of Penicillium marneffei / 中华皮肤科杂志

ABSTRACT

Objective To isolate and purify melanin from yeast cells of Penicillium mameffei (PM) and to analyze its physicochemical features.Methods PM yeast cells were cultured in minimal medium containing levodopa (L-dopa) with continuous shaking at 37 ℃.Melanin was isolated from the yeast cells of PM by cell walllysing enzyme,denaturant,concentrated hot acid,and purified by sodium hydroxide and concentrated hydrochloric acid.The physicochemical properties of isolated melanin were assessed on the basis of combined chemical analysis and spectroscopic methods including ultraviolet-visible (UV-vis),Fourier transform infrared (FT-IR) and electronparamagnetic resonance (EPR).Results Similar to synthetic dopa-melanin,the isolated melanin from PM was alkali soluble,acid-resistant,insoluble in water and most organic solvents,precipitated at or below PH 3,and could be bleached by hydrogen peroxide.UV-vis spectrophotometric analysis showed that the PM-derived melanin had a typical absorption peak at 205 nm and the absorbance decreased with the increase of wavelength.FT-IR spectroscopy displayed two absorption peaks at about 3 μm and 6 μm,which was characteristic of classic melanin.EPR spectroscopy revealed that the isolated melanin contained stable free radicals.Conclusion Yeast cells of PM can use exogenous L-dopa to synthesize dopa-melanin.