Studies On The Antitumor Activity Of α-methyl-γ-lactams And Its Liposomal

α-methyl-γ-lactams, the naturally exist compounds, have a varieity of functionsrelated to anticancer, antibiotics, anti-proteasomes.During our study of α-methyl-γ-lactam’s anti-tumor activity, we found there aresome limitations for its clinical usage. In order to increase its anticancer efficiency, wepropose to use the liposomes as vehicles to deliver the α-methyl-γ-lactams.Liposomes,which contain single or multiple amphiphilic bilayers, have an internal hydrophiliclumen and is widely used as drug carriers during the previous reseaches. Liposomeshave been used to formulate a variety of drugs. A number of hydrophobicchemotherapeutic agents, such as paclitaxel and docetaxel, are incorporate into theliposome’s lipid bilayers, which leads to improved solubility, prolonged circulationtime, ameliorated in vivo distribution and reduced side-effects.Firstly, we established a spectrophotometry assey to quantify theα-methylene-γ-lactam level in its ethanol solution. Secondly, considering the differentsolubility of α-methylene-γ-lactam in various organic solvents and concerning theimpact of the organic solvent on cells, we choose ethanol as the vehicle. Then after avariety experimentations on tumor cell lines and control cell lines, we choicedHEK-293T cells and HeLa cells as our model cells to evaluate α-methylene-γ-lactam.We find one monomer named3Q116rs have a high anti-tumor ability on tumor cellsand show little effect on control cells. The ratio of inhibition effect ofα-methylene-γ-lactam on control cells to tumor cells was1.10, which was higher thanpaclitaxel’s1.09and lower than docetaxel’s1.12. Then optimized the drug loadingefficiency of α-methylene-γ-lactam in liposomes. When the ingredients werecombined in the following ways, the liposomes received the best physics andchemical properties. HSPC: cholesterol: DSPE-mPEG2000=65:34.5:0.5(w:w:w). Thedrug-loading rate was5%, the particle diameter was99nm, ζ potential3.4mv and theencapsulation efficiency was approximately62%under this condition.By utilizing different liposomes having different drug loading value for cellinhibitary experiments, we found that the inhibitory effect of the liposome, L-3Q, on control cells and tumor cells was increased with the increase of drug loading value.The ratio of inhibitory effect on control cells to tumor cell ratio was1.04， which wasless than the positive control and monomers3Q116rs. Using liposomes which werelabeled by the hydrophilic rhodamine and lipophilic NBD-DOPE for flow cytometryexamination and confocal laser test, we find that compared with control, the uptakeamount of NBD and rhodamine, which reflect the size of lipid phase and aqueousphase respectively, increases with time increased. At the same time, the cells absorbL-3Q. With the L-3Q absorbed, the aqueous phase and the lipid phase of liposomestransferred into the cells simultaneously. In addition, the liposomes are clearlyisolated from cell nucleus, which indicates the liposomes are absorbed by the cellswith complete integrity.