Construction Of Natural Triterpenoids Nano-delivery System And Their Application Research On Anti-tumor

As a regular treatment method for cancer,chemotherapy usually causes serious side effects.Although these side effects can be alleviated to some degree by the application of nanocarriers,long-term use of these carriers can lead to metabolic disorders and nanotoxicity in the body bcause most drug carriers are just excipients for drug delivery.Therefore,it is an important challenge to effectively reduce the side effects of chemotherapy drugs and reduce the nanotoxicity induced by drug nanocarriers.Pentacyclic triterpenoids are potential drug resources,which have attracted much attention due to their extensive pharmacological activities and selfassembly properties.In this study,a series of self-assembled and co-assembled nanodrug delivery systems were constructed based on the self-assembly characteristics of triterpenoids.Due to the inherent pharmacological activities,health effects and biosafety of triterpenoids,the system shows excellent synergistic anti-tumor effect or / and slow down side effects of chemotherapy drugs,as well as excellent biosafety.The nanodrug delivery system of ursolic acid(UA)with synergistic antitumor effect was constructed.Twelve triterpene self-assembled nanoparticles(NPs)were prepared by emulsion solvent evaporation method.Among these NPs,UA had spherical morphology and small particle size distribution(< 200 nm),which was suitable for drug loading and transport,and its loading capacity of paclitaxel(PTX)was as high as 23%.The interaction between UA and PTX was analyzed by spectral characterization techniques and derivatization experiments.The results showed that there were hydrogen bonding force and hydrophobic interaction between UA and PTX.The decrease of the binding sites of UA and the extension of hydrophobic side chain would lead to the decrease of drug loading.Cell and animal experiments showed that UA-PTX NPs have good tumor enrichment characteristics.The combination index(CI)of UA-PTX NPs on 4T1 and MCF-7 cell lines were 0.594 and 0.789,respectively.The tumor inhibition rate of UA-PTX NPs was as high as 90% in tumor bearing mice,and the inhibitory effect was 3 times higher than that in PTX injection group.Compared with traditional drug carriers,UA-PTX NPs has unique bioactivity.Oleanolic acid(OA)nanodrug delivery system with multi-biological activity of liver protection and synergistic antitumor was constructed.The drug-loaded NPs of three compounds,oleanolic acid(OA),glycyrrhetic acid(GA)and betulin(Bet),were prepared by emulsification solvent volatilization method.The results showed that the particle size distribution(about 250 nm,PDI < 0.05)and morphology of OA NPs suitable for drug delivery,and OA loaded with PTX was up to 17%.Spectrum analysis showed that there were hydrogen bonding force and hydrophobic interaction between OA and PTX.REMD molecular dynamics simulation showed that steric hindrance had great influence on the interaction between drug and carrier.As a result,the two methyl positions in the OA structure formed a steric hindrance effect with the PTX structure,which made the hydroxyl and carboxyl groups in OA closer to the amide part of PTX to form more hydrogen bonds,while the positions of two methyl groups in UA structure had stronger hydrophobic interaction with benzene ring in PTX.Cell experiments showed that OA NPs had weak synergistic anti-tumor effect on MCF-7 and 4T1 cancer cell lines,CI value both was 0.94.Animal experiments showed that the tumor inhibition rate of OA-PTX NPs was increased by nearly 10% compared with the inactive drug loading particles.In addition,OA can slow down the liver injury induced by paclitaxel through antioxidant pathway.The levels of SOD and GSH in liver tissue of OA-PTX NPs treatment group were increased by 25.8% and 52.0% compared with PTX treatment group,and 24.5% and 42.2% higher than that of PLAG-PTX NPs treatment group,respectively.The co-assembly characteristics of several pentacyclic triterpenoids were found,and a variety of co-assembled NPs were prepared by co-assembly strategy,and the co-assembly mechanism was analyzed with OA-GA and GA-LA NPs as representatives.The results of spectral analysis showed that the two compounds were mainly assembled by hydrogen bonding force and hydrophobic interaction.The results of molecular dynamics simulation showed that the two molecules which could be co-assembled were in parallel plane configuration,and tended to combine at hydrophilic sites,and the two non-co-assembled molecules were stereoscopic and close to hydrophobic end.The results of cell and animal experiments showed that OA-GA NPs and GA-LA NPs had a strong synergistic effect on MCF-7 cell lines with CI values of 0.62 and 0.34,respectively.In addition,OA-GA NPs can also be loaded with about 15% mass fraction of PTX,which further improves the anti-tumor effect.the tumor inhibition rates of OA-GA NPs and GA-LA NPs were 64.8% and 72.8%,respectively,which were more than 20% higher than that of self-assembled NPs;the tumor inhibition rate of OA-GA-PTX NPs was 82.6%,which was further enhanced than that of co-assembled NPs.Systemic toxicity and histological analysis confirmed that the co assembled NPs had reliable biological safety.