title: Preparation of melanin from Catharsius molossus L. and preliminary study on its chemical structure.
abstract: A great deal of melanin was found in the waste alkali liquor produced by extraction of chitin from Catharsius molossus L. Discarding the lye could harm the environment and cause waste of resources. In this paper, melanin from C. molossus L. was recovered through acid precipitation and purified by pepsin and so on. The purity, chemical composition and structure of the prepared melanin were explored by UV-visible absorption spectroscopy, Fourier transform infrared spectroscopy, proton nuclear magnetic resonance spectroscopy, high resolution (13)C Cross polarization magic angle spinning nuclear magnetic resonance spectroscopy pyrolysis gas chromatography mass spectrometry, X ray diffraction, X ray fluorescence, matrix-assisted laser desorption/ionization time of flight tandem mass spectrometry, thermal analysis, and so on. The results showed that the purity of the prepared melanin was higher than the commercial standard melanin and it was a kind of nanoaggregates composed of a large quantity of 5,6-dihydroxyindole eumelanin and a small amount of phaeomelanin. In addition, the prepared melanin was irregular in shape and its structure could be divided into three levels: advanced structure maintained by polypeptides, substructure maintained by the ferric ion and microstructure. In particular, the smallest structural unit showed the graphite-like layered structure containing five layers linked by non-covalent bonds and each layer mainly consisted of 5,6-dihydroxyindole and its derivatives, which might be connected to each other through various chemical bonds.
authors.affiliation: Engineering Research Center for Biomass Resource Utilizaiton and Modification of Sichuan Province, Southwest University of Science and Technology, Mianyang 621010, China. Electronic address: xinchao198811@126.com.
authors.forename: Chao
authors.initials: C
authors.lastname: Xin
authors.affiliation: Engineering Research Center for Biomass Resource Utilizaiton and Modification of Sichuan Province, Southwest University of Science and Technology, Mianyang 621010, China.
authors.forename: Jia-hua
authors.initials: JH
authors.lastname: Ma
authors.affiliation: Mianyang Normal University, Mianyang 62100, China.
authors.forename: Cheng-jia
authors.initials: CJ
authors.lastname: Tan
authors.affiliation: Engineering Research Center for Biomass Resource Utilizaiton and Modification of Sichuan Province, Southwest University of Science and Technology, Mianyang 621010, China.
authors.forename: Zhou
authors.initials: Z
authors.lastname: Yang
authors.affiliation: Engineering Research Center for Biomass Resource Utilizaiton and Modification of Sichuan Province, Southwest University of Science and Technology, Mianyang 621010, China.
authors.forename: Feng
authors.initials: F
authors.lastname: Ye
authors.affiliation: Engineering Research Center for Biomass Resource Utilizaiton and Modification of Sichuan Province, Southwest University of Science and Technology, Mianyang 621010, China.
authors.forename: Chan
authors.initials: C
authors.lastname: Long
authors.affiliation: Engineering Research Center for Biomass Resource Utilizaiton and Modification of Sichuan Province, Southwest University of Science and Technology, Mianyang 621010, China.
authors.forename: Shuang
authors.initials: S
authors.lastname: Ye
authors.affiliation: Engineering Research Center for Biomass Resource Utilizaiton and Modification of Sichuan Province, Southwest University of Science and Technology, Mianyang 621010, China.
authors.forename: Da-bin
authors.initials: DB
authors.lastname: Hou
mesh_terms: D000818:Animals; D002686:Chitin / Q000737:chemistry / Q000302:isolation & purification; D001517:Coleoptera / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D008543:Melanins / Q000032:analysis / Q000737:chemistry* / Q000302:isolation & purification*; D017550:Spectroscopy, Fourier Transform Infrared; D013696:Temperature; D014961:X-Ray Diffraction
chemical_list: D008543:Melanins; C016042:phaeomelanin; C041877:eumelanin; D002686:Chitin
keywords: Catharsius molossus L.; Chemical structure; Melanin