Reparative Effects of Astaxanthin-Hyaluronan Nanoaggregates against Retrorsine-CCl₄-Induced Liver Fibrosis and Necrosis.

Astaxanthin (Asta), a xanthophyll carotenoid, has been reported to be a strong antioxidative agent and has anti-inflammatory, antitumor and free radical-scavenging activities. However, inadequate stability and water solubility results in its low bioavailability. This study incorporated Asta into hydrophilic hyaluronan nanoparticles (HAn) to produce Asta-HAn aggregates (AHAna) using an electrostatic field system and investigated the restorative effects of AHAna on retrorsine-CCl₄-induced liver fibrosis in rats in vivo. Transmission electron microscopy (TEM) revealed that the prepared HAn were approximately 15 ± 2.1 nm in diameter and after the incorporation of Asta into HAn, the size increased to 210-500 nm. The incorporation efficiency of Asta was approximately 93% and approximately 54% of Asta was released after incubation for 18 h. Significant reductions in alanine aminotransferase and aspartate aminotransferase levels were observed after the rats were intraperitoneally injected with AHAna. Histopathological findings revealed the greatest reduction in hepatic fibrosis and hepatocyte necrosis in the rats after 2 weeks of intraperitoneal injection with AHAna, which is consistent with the data acquired from serum biochemical analysis. The restorative effects on liver damage displayed by AHAna in vivo demonstrated that Asta aggregated through HAn incorporation exerts therapeutic effects on liver fibrosis and necrosis.