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Chitosan from Catharsius molossus L.was found superior to commercial pharmaceutical-grade chitosan from crabs and shrimps in many kinds of properties such as film-forming, acid resistance, enzyme resistance, bioadhesion, rheology residual quantity of heavy metal, which showed it was more suitable for carrier of colon-specific drug delivery system by preliminary studies.In this paper, the structure of chitosan from Catharsius molossus L.was studied by some methods such as oxidation-HPLC, 1H-NMR, thermal analysis, elemental analysis, UV-visible spectrophotometry etc and we found there was some eumelanin in chitosan.In addition, the preliminary conclusion was obtained that the eumelanin and N-acetyl-D-glucosamine(the monomer of chitin) may be connected together with the form of schiffbase(-CH2-NH-)by chemical synthesis in vitro and the analysis of enzymatic hydrolyzate of chitin from Catharsius molossus L..Chitosan from Catharsius molossus L.was speculated that it was in the form of chitosan/chitin-melanin complex, which made it superior to ordinary chitosan in properties of film-forming , acid resistance, enzyme resistance etc.Studies also have shown that chitosan-melanin complex which contents moderate melanin from Catharsius molossus L.is even more suitable as the carrier of colon-specific drug delivery system.If chitosan-melanin complex is used to film-coating material, the pH-sensitive layer and enzymes-trigger layer will combine into one layer and the limitations of ordinary double-coated form may be broken in colon-specific bioadhesive tablets.In the future, we will choose polypeptide extract from Catharsius molossus L.as crude material and chitosan-melanin complex from Catharsius molossus L.as coating material to prepare colon-specific bioadhesive drug delivery system, which may be similar to the structure of live insects and will achieve good results in the treatment of benign prostatic hyperplasia.