Research On The Therapeutic Effects Of Ginsenosides And Its Brain-targeted Liposomes On Ischemic Stroke

Ischemic stroke(IS)is a common brain disease,which is usually treated with neuroprotective agents.However,due to the pathological state of vascular occlusion and the presence of the Blood brain barrier(BBB),it is difficult to enter the brain,which greatly limits its therapeutic effect.Therefore,it’s the key to IS treatment to realize drug enrichment at ischemic site.:This study uses a leukocyte-mediated approach to deliver drugs into the brain based on the characteristics of leukocyte aggregation at the site of ischemic inflammation following ischemia-reperfusion(I/R).Firstly,ginsenosides with the best therapeutic effect on IS was selected from 6 ginsenosides as model drug.Then ginsenoside liposome was prepared and PGP target was modified on the surface of the liposome to mediate neutrophil endocytosis of the liposome and carry the liposome across BBB to reach an inflammatory region in the brain.Finally,the neutrophils fuse with the diseased neuronal cells,and the liposome enters the neuronal cells and slowly releases the drug to achieve the purpose of drug accumulation in the lesion.1.Comparison of neuroprotective effects of ginsenosides on cerebral ischemia and its mechanismA CoC12-induced PC 12 cell injury simulation I/R injury model and a middle cerebral artery occlusion(MCAO)reperfusion model were established to compare the in vivo and in vitro efficacy of 6 ginsenosides in ischemic stroke.The results showed that ginsenosides Rbl and Rg3 have the most significant in vivo and in vitro effects on IS,and Rb1 and Rg3 belong to type A of panaxadiol,indicating that the therapeutic effect of ginsenoside on IS may be related to its molecular structure.The mechanism of ginsenosides in the treatment of IS was studied.The results showed that after the intervention of ginsenosides in MCAO model rats,TNF-α,IL-1β,IL-6,TLR4,NF-κB P65 and MyD88 expression decreased and SIRT1 expression increased.It is indicated that ginsenosides can interfere with the expression of inflammatory factors by inhibiting TLR4/MyD88 signal pathway and/or activating SIRT1/NF-κB signal pathway,thus playing a therapeutic role on IS.2.Preparation and brain targeting of PGP modified brain-targeted liposomesFirstly,PGP target was successfully synthesized,and the optimal modification ratio of PGP target was 3%.Then Rb1-Lp,Rg3-Lp,PGP-Rb1-Lp and PGP-Rg3-Lp were prepared by thin film dispersion method,and liposomes were characterized.The results showed that the average particle size of the four liposomes was less than 110nm,PDI was less than 0.3,and the entrapment efficiency of ginsenoside was above 80%.TEM observation showed that the liposome was uniform n size,round in shape and clear in outline,which met the experimental requirements.Next,brain targeting evaluations were performed on liposomes.Transwell test results verified the process of neutrophils carrying liposomes across BBB.In vivo imaging results of small animals show that ginsenoside Rbl,Rg3 and PGP target can significantly increase the accumulation of liposomes in the brain,and ginsenoside and PGP target have synergistic targeting effect,enabling liposomes to circulate in the brain for a long time.Compared with other groups,PGP-Rbl-Lp and PGP-Rg3-Lp groups can significantly increase the accumulation of drugs in cerebral ischemia sites,with significant secondary brain targeting effects.3.Pharmacodynamic evaluation and mechanism of PGP-Rb1-Lp and PGP-Rs3-LpTTC staining and MRI results show that PGP-Rbl-Lp and PGP-Rg3-Lp can significantly improve the therapeutic effect of IS compared with ginsenoside free drugs.The mechanism study showed that after MCAO rats were intervened by PGP-Rb1-Lp and PGP-Rg3-Lp,the release amount of HMGB1,p65,TNF-α,iNOS,NO,IL-6 and the protein expression amount of caspase-3 and caspase-9 in cerebral ischemia area were significantly reduced,which indicated that ginsenoside could treat cerebral ischemic injury by inhibiting inflammatory reaction and reducing cell apoptosis.In summary,this topic compared the IS efficacy of six ginsenosides,determined that ginsenoside Rbl and ginsenoside Rg3 had the best therapeutic effect,and studied the mechanism of action.Next,the PGP modified ginsenoside-loaded liposome brain targeting drug delivery system was successfully constructed,and the multi-level brain targeting property of the drug delivery system was verified.Finally,the pharmacodynamics evaluation and mechanism research of PGP-Rbl-Lp and PGP-Rg3-Lp were carried out.