Studies On The Excipient Suitability Of Chitosan From Catharsius Molossus L. And Its Chemical Structure

Chitosan was the important excipient material of colonic adhesive tablets. But, some problems existed in the ordinary chitosan including low viscosity, low mechanical strength of its film, strong hydrophilicity, poor acid resistance, limiting its development as the excipient material.It was found hydrated chitosan from Catharsius molossus L. still showed the superior performance and it might be the complex composed of chitosan and melanin by the preliminary experiments. In order to provide theoretical support for the development of this resource, the excipient suitability of chitosan and chemical structure from Catharsius molossus L. were studied in this paper. The main results are as follows:Chitin of Catharsius molossus L. was prepared with acid- base methods and was deacetylated in the improved intermittent heating way; The chitosan complex from Catharsius molossus L. was characterized in fifteen aspects including deacetylation, viscosity, ash content, adhesion in vitro, heavy metal content residues of the protein, rheological properties, compared with commercial medical-grade chitosan from shrimp and homemade shrimp chitosan. It was found the chitosan complex from Catharsius molossus L. was superior to the other two classes of chitosan in all indicators; Further, films of the chitosan complex from Catharsius molossus L. and commercial medical-grade chitosan from shrimp was was characterized in nine aspects including morphology, hydrophobicity, acid resistance, enzyme resistance, transmittance and mechanical strength and adhesion of hydrated chitosan films. The results showed the former was more superior in the excipient performance..Comprehensively, the chitosan complex from Catharsius molossus L. was more suitable to act as the spharmaceutical excipients of colonic adhesive tablets than commercial medical-grade chitosan from shrimp.The structure of chitosan complex from Catharsius molossus L. was studied from the macro and micro level. Macro level:Its chemical structure was explored by NMR, IR, UV, Py-GC/MS, thermal Analysis, XRD, etc. Micro level: The chitosan complex from Catharsius molossus L. was hydrolyzed by the chitosanase and cellulase, then, the hydrolyzate was isolated by HP-20 macroporous resin and Sephadex G-15. Finally, the structure of product isolated by gel was explored using Elemental analysis, NMR, MALDI-TOF / TOF, UV, Oxidation-LC-MS, etc. The results showed eumelanin and glucosamine and N- acetyl glucosamine was linked through an ester group bond to constitute the main structure of chitosan complex from Catharsius molossus L.