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.
Subject(s)
Coleoptera/chemistry , Melanins/chemistry , Melanins/isolation & purification , Animals , Chitin/chemistry , Chitin/isolation & purification , Magnetic Resonance Spectroscopy , Mass Spectrometry , Melanins/analysis , Spectroscopy, Fourier Transform Infrared , Temperature , X-Ray DiffractionABSTRACT
OBJECTIVE: Decolorization of crude chitin from Catharsius molossus was studied in order to prepare chitosan with white color and high viscosity. METHODS: Some factors affecting decolorization such as the kind of decolorant reagent, H2O2 concentration, pH, solid-liquid ratio, temperature and other factors were studied by single factor test and orthogonal design. RESULTS: The best decolorization process of chitin from Catharsius molossus was as follows:treated with 15 times of 15% H2O2 at 45 degrees C. CONCLUSION: The process is stable and feasible. The chitosan from Catharsius molossus might be used as a new carrier of colon-specific drug delivery system.
Subject(s)
Chitin/chemistry , Chitosan/chemistry , Coleoptera/chemistry , Hydrogen Peroxide/chemistry , Materia Medica/chemistry , Animals , Chemistry, Pharmaceutical/methods , Hydrogen-Ion Concentration , Temperature , ViscosityABSTRACT
OBJECTIVE: To study preparation and characterization of chitosan from Catharsius Molossus processing discards and explore the feasibility of utilization of insects residue. METHODS: Preparation technique of chitosan was studied by orthogonal design,and properties were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), etc. RESULTS: Preparation techniques were as follows: demineralizing: soaked for 30 min at 80 degrees C with 1.3 mol/L HCl, then kept for 12 h under room temperature. Deproteinization and delipidation: treated for 6 h at 90 degrees C with 4 mol/L NaOH. Decolorizing: soaked at room temperature with 3% KM-nO4, then treated with 2% oxalic acid at 70 degrees C. Deacetylating:treated for 5 h at 110 degrees C with 14 mol/L NaOH. CONCLUSION: The technique is stable and feasible. The result also preliminarily showes that chitosan from Catharsius Molossus is better than shrimp's. It will be widely applied in biomedical and other industrial areas with such exciting properties.
