Preparation Of Baicalin Liposomes Based On "Inflammatory Targeting" And Its Mechanism Of Acute Cerebral Ischemia Injury

Baicalin is one of the effective active components of the traditional Chinese medicine Scutellaria baicalensis Georgi?Scutellaria baicalensis Georgi?.It has extensive pharmacological effects,scavenging oxygen free radicals,protecting the heart and brain blood vessels and protecting the nervous system.Due to poor solubility,baicalin oral preparation is not only of low bioavailability but also lacks certain brain targeting for the treatment of brain diseases.Objective:To improve the liposoluble properties of baicalin and increase the permeability of the membrane,it is prepared into a liposome with specific external characterization,trying to improve the bioavailability and the brain targeting.Through the biotic behavior of baicalin liposome?BA-LP?in the rat model of acute cerebral ischemia,the ischemic group is verified by ischemic injury.Weave the role of Enhanced Permeability and Retention effect?EPR?,which is similar to tumor,in"inflammatory targeting".Method:1 Through single factor correlation analysis,it was found that the effect of hydration vol?me on encapsulation efficiency was very significant?P<0.01?,Box-behnken Design was optimized,and the optimal prescription of baicalin liposome was as follows:the proportion of phospholipid liposomes was 3.81:1,the proportion of phospholipid cholesterol was 5.70:1,the vol?me of hydration was1.02mL,ultrasonic power 60W,ultrasonic time 10min,and ultrasonic temperat?re 205 degree C.2 The particle size and Zeta potential of baicalin liposomes were measured by Malvin particle size analyzer,and the appearance of BA-LP was observed by transmission electron microscope.Zero order kinetics,first-order kinetics,biphasic kinetics,Niebergull and Hig?chi models were used to sim?late in vitro release of BA-LP and BA.3 Pharmacokinetics and distribution st?dy:the model of acute cerebral ischemia reperfusion was prepared by thrombus line method.HPLC was used to analyze baicalin in biological samples.The pharmacokinetics and tissue targeting of baicalin liposomes and monomers were compared in normal and ac?te cerebral ischemia-reperfusion rats.4 TTC staining,cerebral edema and neurological function score were used to j?dge the success of acute cerebral deficiency model and the protective effect of Baicalin on acute cerebral ischemia.The changes in the activity of SOD and LDH at different time points in plasma and brain tiss?e were meas?red by the kit.The method of quantitative correlation between baicalin concentration time and efficacy was established by using the scatter point correlation method?Y=a+b*lnx?in DAS3.1.1software.Result:1 Through single factor correlation analysis,it was found that the effect of hydration volume on encapsulation efficiency was very significant?P<0.01?,Box-behnken Design was optimized,and the optimal prescription of baicalin liposome was as follows:the proportion of phospholipid liposomes was 3.81:1,the proportion of phospholipid cholesterol was 5.70:1,the vol?me of hydration was1.02mL,ultrasonic power 60W,ultrasonic time 10min,and ultrasonic temperature 20±5 degree C.2 The external morphology of BA-LP is spherical particles,the particle size is160-190 nm,the PDI value is 0.190-0.224,and the potential is-5.7 mV.The release conforms to the biphasic dynamic model in vitro,which has the sustained release effect.3 Pharmacokinetics and distribution studies:This study compared the distribution of the pharmacokinetic tissue of the normal and acute cerebral ischemia reperfusion model rats,after the hypoglossal vein injection of baicalin liposomes and monomers:the AUC_?0-??in the normal gro?p of baicalin liposome?BA-LP?was higher than that of the normal group?BA??P<0.01?,half of the normal group?P<0.01?.The t_1/2 in the normal group of BA-LP was 1.62 times longer than that in the normal BA-LP gro?p?P<0.01?.Compared with the normal BA-LP group,the plasma AUC?0-t?,AUC_?0-??,MRT in the BA-LP model group were significantly higher than that in the BA-LP model group.The bioavailability of liposomes was 4.728%.It shows that baicalin liposomes can prolong the retention time of Baicalin in vivo,which has a narrow distribution range and improves the bioavailability of drugs in vivo.Arget evaluation results:for BA-LP model group,the TE from large to small in each group was:striatum?26.610%?>olfactory bulb?15.210%?>hippocampus?12.379%?>kidney?9.246%?>cortex?8.558%?>cerebellum?7.161%?>liver?6.390%?>spleen?5.660%?>heart?4.213%?>lung?4.213%?;for BA model group,TE was in each group.The order from large to small was:kidney?20.988%?>striatum?17.814%?>olfactory bulb?15.716%?>hippocampus?14.241%?>cortex?11.358%?>cerebellum?5.611%?>liver?5.667%?>lung?5.538%?>heart?2.407%?>spleen?0.634%?.Compared with the BA model,the BA-LP model group enhanced the targeting of the brain tissue,especially targeting the striatum,olfactory bulb and hippocampus,and reduced the selectivity to the kidney by 2.296 times.The results showed that baicalin liposomes had brain targeting.4 Pharmacodynamics and PK-PD correlation study:the results of TTC staining,brain edema and nerve function score showed that baicalin liposomes have protective effect on acute cerebral ischemia.According to the PK-PD model,the results showed that the concentration of Baicalin in plasma and SOD was YSOD=224.859-2.34 lnX,?r=-0.861,p=0.006?,and the equation of baicalin concentration and LDH was YLDH=7319.867+53.096 lnX,?r=0.924,P=0.001?after BA.The equation of baicalin concentration and SOD in plasma was Y_SOD=185.248+15.605 lnx,?r=0.691,P=0.027?,and the fitting eq?ation of baicalin concentration and LDH was Y_LDH=5513.347+64.377 lnx,?r=0.856,P=0.002?after BA-LP.The change of SOD and LDH in plasma may be related to the time lag of baicalin efficacy.Conclusion:The reverse evaporation method has the highest BA-LP encapsulation rate and the smallest particle size,and the method is feasible.In vitro,the release process of BA-LP conforms to the biphasic characteristics.In vivo pharmacokinetics and tiss?e targeting show that baicalin liposome has sustained release effect and can prolong the retention time of Baicalin in the body and has a narrow distribution range.In the acute cerebral ischemia model,it is proved that there is a"inflammatory targeting"effect similar to the"EPR"effect of the t?mor.BA-LP can accumulate in the ischemic brain tiss?e and have the effect of brain targeting.