Preparation and evaluation of PEGylated asiatic acid nanostructured lipid carriers on anti-fibrosis effects

Liver fibrosis is a major pathological feature of chronic liver diseases, and effective therapies are limited at present. Asiatic acid (AA) is a triterpenoid isolated from Centella asiatica, which exhibits efficient anti-inflammatory and anti-oxidative activities. However, AA shows very low plasma levels after oral administration. In this study, AA loading PEGylated nanostructured lipid carriers (P-AA-NLCs) were prepared. P-AA-NLCs were characterized for particle size distribution, polydispersity index, entrapment efficiency, X-ray powder diffraction (XRD) pattern, differential scanning colorimeter (DSC), and transmission electron microscopy (TEM). The intestinal absorption, in vivo distribution, pharmacokinetics, and anti-fibrosis effects of P-AA-NLC were studied compared with that of AA-NLC. In situ single-pass intestinal perfusion model shows that there are significant differences in absorption between the free and NLCs formulation. The P-eff values of P-AA-NLC were significantly enhanced in all four intestinal segments compared to AA-NLC and free AA (p < .05). f(a)% and K-a showed similar trends, suggesting the PEGylated NLC can improve the gastrointestinal absorption of the drug. The pharmacokinetic studies presented that P-AA-NLC prolonged blood circulation times with a 1.5-fold higher relative bioavailability compared with AA-NLC. In vivo distribution experiments demonstrated that the fluorescence concentration in the liver was higher than that in other organs and the fluorescence intensity in the liver of DIR-P-NLC was about 1.3 times that of DIR-NLC. In addition, oral administration of P-AA-NLC can significantly attenuate CCl4-induced liver fibrosis and functional impairment in a dosage-dependent manner, including an increase in the albumin (ALB) and decrease in aspartate aminotransferase (AST) and alanine transaminase (ALT). Moreover, the MDA and HYP in liver tissue were downregulated, while the SOD activity was upregulated. In conclusion, P-AA-NLC can increase gastrointestinal absorption of AA and enhance anti-liver fibrosis effects in SD rats.