Nanoformulation Of Dual Bexarotene-tailed Phospholipid Conjugate With High Drug Loading

Bexarotene(Bex),a synthetic retinoid X receptor-selective activator,has been proved to be an efficacious chemotherapeutic agent.But,its clinical application is limited due to the poor solubility.In this report,dual bexarotene-tailed phospholipid(DBTP)conjugate based nanovesicles were prepared in order to develop new nanoformulation.The main content and results of the thesis are as follows:(1)Firstly,dual bexarotene-tailed phospholipid(DBTP)prodrug was synthesized by conjugating Bex with glycerophosphorylcholine(GPC)through facial esterification using CDI/DBU catalytic system.HPLC,MS and NMR were applied to characterize the target product DBTP.Secondly,electric conductivity measurement was used to determine the critical aggregation concentration(CAC),which reflected the self-assemble ability of DBTP.Nanovesicles assembled from DBTP were prepared by reverse-phase evaporation method.This novel nanoformulation of bexarotene has high drug loading(76 wt%).The DBTP nanovesicles have a spherical structure with an average diameter approximately 138.7 nm,characterized by dynamic light scattering(DLS)and transmission electron microscopy(TEM).In vitro degradation and release study confirmed the excellent stability of DBTP-Lips in neutral environment and sustained release of bexarotene in weak acid condition.Finally,Cellular uptake was studied by confocal laser scanning microscope(CLSM)and liquid chromatography-mass spectroscopy(LC-MS).The results demonstrated the successful internalization and intracellular release behavior of DBTP-ves.In vitro cytotoxicity analysis and apoptosis of DBTP-ves showed higher anticancer efficiency compared with free Bex after 72h of incubation.(2)Secondly,in order to accelerate the degradation rate and drug release of nanovesicles,dual bexarotene-hexandiolsuccinat phospholipid(DB-ES-TP)prodrug was synthesized by conjugating Bex with glycerophosphorylcholine(GPC)using hexylene glycol and succinic anhydride as linkers.Reverse-phase evaporation method was applied in preparing DB-ES-TP nanovesicles.The DB-ES-TP nanovesicles have a spherical structure with an average diameter about 227.2 um characterized by DLS and TEM.In in vitro release study,DB-ES-TP-ves exhibited minimize premature leakage in neutral environment and controlled release of Bex in weak acid condition.Finally,CLSM and LC-MS study confirmed the successful internalization and intracellular release behavior of DB-ES-TP-ves.Cytotoxicity assay(MTT)was used to evaluate the in vitro anticancer activity of DB-ES-TP-ves.The results showed that the IC50 of the DB-ES-TP nanovesicles on MCF-7 and A549 cancer cell lines were 17.4 and 13.5 ?g/mL,respectively,indicating higher toxicity in comparison with Bex after 36 h incubation.In conclusion,bexarotene-phospholipid conjugates has capability of assembling into nanovesicles.This novel bexarotene delievery system has high drug loading,no premature leakage and effective ancancer activity.Therefore,it may be an effective alternative in improving the therapeutic effect of Bex.