Nasal Temperature-/Ion-Sensitive In Situ Hydrogels Of Timosaponin BII For Preventive Action On Alzheimer's Disease Of Mice

Objective: To prepare the nasal in situ hydrogels(ISG)of timosaponin BII for preventive action on Alzheimer's disease.Methods: Poloxamer 407 and deacetylated gellan gum were as the ISG matrix.Phase transition temperature and gelation time were the evaluation index to optimize the formulation.The different penetration enhancers and the bacterial inhibitors were optimized on oscillation of toad palate mucosa ex vivo.And the major penetration enhancers,including ?-,hydroxypropyl-?-and sulfobutyl-?-cyclodextrin,were further evaluated by isolated sheep nasal mucosa in vitro.The characteristics of optimized formulation were assessed.Established PC12 cell injury model induced by lipopolysaccharide in vitro.Investigated the preventive action of timosaponin BII on scopolamine or lipopolysaccharide induced Alzheimer's disease of mice.Brain targeting was explored with tissue distribution.Safety was estimated on rabbit eyes to evaluate mucous irritation.Results: The content determination of timosaponin BII was established by HPLC.And the optimal formulation of temperature-/ion-sensitive nasal in situ hydrogels was determined.Release of temperature-/ion-sensitive in situ hydrogels of timosaponin BII in vitro was in accordance with the first-order kinetic equation and the stability was good.Pharmacodynamics in vivo showed that timosaponin BII could significantly shorten the escape latency,decrease the number of passive avoidance and increase the content of M1 type choline receptor in the hippocampus of mice with Alzheimer's disease induced by scopolamine.Timosaponin BII could also significantly shorten the escape latency,reduce the number of passive avoidance,inhibite the release of inflammatory factors TNF-? and IL-1?,and decrease the content of inducible nitric oxide synthase(i NOS)in the brain of mice with Alzheimer's disease induced by lipopolysaccharide.It demonstrated the preventive action of timosaponin BII temperature-/ion-sensitive nasal in situ hydrogels on Alzheimer's disease.Cytotoxic test showed that timosaponin BII could significantly increase the survival rate of PC12 cells,inhibit the release of cytokines TNF-? and IL-1?,protect the structure of F-actin in PC12 cells,and reduce the damage of PC12 cells.Near infrared fluorescence imaging showed that timosaponin BII temperature-/ion-sensitive nasal in situ hydrogels could achieve brain-targeted delivery of drugs quickly and effectively.The formulation did not demonstrate mucosal irritation.Conclusion: The formulation and preparation of timosaponin BII-loaded temperature-/ion-sensitive nasal in situ hydrogels are reasonable,safe,stable and brain-targeting,which provide a new choice for prevention of Alzheimer's disease.