Self-assembly and cytotoxicity study of PEG-modified ursolic acid liposomes

• The optimum formula for assembling of ursolic acid liposomes was determined.
• The liposomes modified by PEG possessed higher trapping efficiency and better stability.
• PEG-modified liposomes presented stronger rigidity and more perfect morphology.
• PEG-modified liposomes maintained the effective therapeutic concentration for a long period of time.
• The results showed that PEG-modified liposomes exhibited better antitumor activity.

While ursolic acid (UA), one of the most broadly known triterpene compounds, has proved to be effective in cancer therapy, the applications of UA is limited due to its poor aqueous solubility and low bioavailability. The aim of our study was to prolong circulation time and enhance uptake of liposomes in tumor tissues through the modification of UA liposomes via water-soluble polyethylene glycol (PEG). In addition, this research also focuses on physicochemical properties of the liposome formulations, including encapsulation efficiency, particle morphology, size, stability, release rate in vitro and cytotoxicity test. The obtained liposomes were spherical particles with mean particle diameters around 100–200 nm. And the Fourier transform infrared spectroscopy (FTIR) indicated that PEG had been anchored successfully to the liposomes. Based on our experimental data achieved, PEG-modified UA liposomes possessed higher stability than conventional liposomes, and the release rate of UA from PEG-modified liposomes was slower when compared with those of UA solution and conventional liposomes. Meanwhile, the liposomal UA showed relatively low cytotoxic effect than UA conventional liposomes within 24 h, which was consistent with their release rates.

The higher encapsulation efficiency, appropriate size, long-circulating effect and stability made PEG-modified ursolic acid liposomes more superior, and laid the foundation for antitumor studies.Figure optionsDownload as PowerPoint slide