Preparation And Research Of Betulinic Acid Phospholipid Complex/TPGS Mixed Micelles

Betulinic acid(BA)is a pentacyclic triterpene compound.It has been found that it can inhibit many kinds of tumor cells and has a good development prospect.But the water solubility and bioavailability of betulinic acid are very low.Therefore,a micelle loaded with betulinic acid is prepared to improve the physicochemical properties and bioavailability of betulinic acid and give full play to its pharmacological effects.Betulinic acid phospholipid complex(BA-PC)is prepared by solvent method,the best preparation technology is selected by using the complexing rate as the evaluation index: using chloroform as solvent,betulinic acid reaction concentration of5 mg/m L,the mass ratio of betulinic acid to phospholipid is 1:2,the reaction temperature is 55℃,the reaction time is 2 hours.The complexing rate of BA-PC is(99.5±0.31)%.The results of FTIR and XRD showed that BA-PC is different from the physical mixture of betulinic acid and phospholipids,which indicated that BA-PC is successfully prepared.Some of them existed in an amorphous state,and some of them are attached to phospholipids in a crystallized state after the crystal form is changed.Betulinic acid phospholipid complex/TPGS mixed micelles(BA-PC/TPGS mixed micelles)is prepared by solvent evaporation method,the best preparation technology is selected by using the entrapment efficiency and drug loading as the evaluation index: the dosage of BA-PC is 22.5 mg(BA:PL=1:2,w/w),the mass ratio of phospholipid to TPGS is 1:2,the volume ratio of organic phase to water phase is1:3,the reaction temperature is 45℃,and the reaction time is 1 hour.The entrapment efficiency and drug loading of BA-PC/TPGS mixed micelles are(87.5±1.35)% and(12.7±0.27)%,respectively.The size,polydispersity,zeta potential of mixed micelles are 69.2 nm,0.287,-19.9 m V,respectively.The mixed micelles are near spherical and had good drug release behavior.The results of FTIR and XRD showed that the mixed micelles are successfully prepared and existed in an amorphous state.BA-PC/TPGS mixed micelles freeze-dried products are prepared.The morphology,redispersivity,size,polydispersity and entrapment efficiency of micelles after lyophilization are taken as the indexes,and 1% polyethylene glycol 6000 is selected as the lyophilization protectant.It is found that high temperature will affect the storage stability of the product in influence factor test.The safety of the micellar solution and the lyophilized hydration solution is investigated by hemolysis test.The results showed that the hemolysis rates are lower than 5% when the concentration of betulinic acid is lower than 15 μg/m L.The inhibitory effect of betulinic acid and BA-PC/TPGS mixed micelles on the proliferation of AGS,He La and HT-29 cancer cells are investigated by MTT assay.The inhibitory effect of BA-PC/TPGS mixed micelles on the proliferation of AGS,He La and HT-29 cancer cells are stronger than betulinic acid at the same concentration.To investigate the uptake of betulinic acid and BA-PC/TPGS mixed micelles in AGS,He La and HT-29 cancer cells,the mixed micelles uptake of the cells are significantly higher than that of the original drug at the same time.