Objective: To optimize formulation process of ursolic acid solid lipid nanoparticles and investigate its physicochemical properties and antitumor activity. Method: Ursolic acid solid lipid nanoparticles was prepared by film dispersion method

orthogonal test was adopted to optimize formulation process by taking encapsulation efficiency as index.Its physical and chemical properties were studied by transmission electron microscope and laser particle sizer/Zeta potential system

MMT was used to detect its in vitro anti-tumor activity. Result: The best formulation process was as following:ursolic acid 90 mg

lecithin 30 mg

stearic acid 10 mg

PBS concentration of 10 mmol·L-1.These prepared nanoparticles showed spherical or ellipsoidal under transmission electron microscope

average particle size

encapsulation efficiency and drug loading were (184.7±18.3)nm

(82.6±0.6)% and (11.9±0.5)%

respectively;release was 81.2% at 48 h

particle size and encapsulation efficiency had no significant change in 30 d.When the concentration of ursolic acid were 5

10

20

40

80 μmol·L-1

inhibition rates of ursolic acid on human hepatoma cell line SMMC-7721 were (9.0±1.2)%

(15.7±2.8)%

(42.3±4.6)%

(78.7±6.9)% and (79.3±7.2)%

inhibition rates of ursolic acid solid lipid nanoparticles were (9.0±1.3)%

(23.6±2.2)%

(59.3±6.1)%

(84.7±8.3)% and (85.0±8.1)%

respectively. Conclusion: These prepared ursolic acid solid lipid nanoparticles have appropriate size

good in vitro release and stability with excellent antitumor activity.