Abstract: In order to optimize the extraction conditions of skin melanin from giant salamander,the composition of skin melanin and its antioxidant activity in vitro were studied.The melanin of giant salamander skin was extracted by enzymatic method and alkali solution acid precipitation method.Taking sodium hydroxide concentration,solid-liquid ratio and extraction temperature as factors and optimizing the melanin extraction process.We also determined its spectral characteristics by ultraviolet-visible spectroscopy,infrared spectroscopy,ultra-high performance liquid chromatography mass spectrometry and its antioxidant effect.The results showed that the optimum extraction conditions of skin melanin from giant salamander were sodium hydroxide concentration 1.5 mol/L,solid-liquid ratio 1∶15,extraction temperature 45 ℃,and the extraction rate of melanin was 0.65%.The maximum absorption wavelength of skin melanin of giant salamander is 214 nm,which is composed of two pigments:eumelanin and phaeomelanin.The scavenging rate of superoxide anion radical and hydroxyl radical was 30.51% and 54.17% respectively.In general,giant salamander skin melanin has antioxidant activity in vitro.

Key words: giant salamander, melanin, extraction process, antioxidant