Improved membrane transport of astaxanthine by liposomal encapsulation

Astaxanthine (3,3'-dihydroxy-beta,beta'-caroten-4,4'-dione) (AST), a red-colored carotenoid pigment, possesses extremely powerful antioxidative activity. However, its drawbacks reside in poor solubility in aqueous system, resulting in extremely low bioavailability. To ameliorate such defects, we prepared AST encapsulated within liposomes (AST-L) and tested with Hep3B and HepG2 cell lines. AST-L had size 251+/-23 nm with AST content 89.0+/-8.6 mg/g. AST-L apparently showed improved stability and transportability. The overall transport time was 7.55 h and 6.00 h for free AST and AST-L, respectively. AST-L more effectively activated antioxidant enzymes like superoxide dismutase, catalase and glutathione S-transferase than free AST. Hep3B consumed AST more rapidly than HepG2 cell lines. Moreover, AST-L when combined with gamma radiation (10 Gy) therapy potentially triggered subG(1) arrest in Hep3B and HepG2 cell lines in a dose-responsive manner (p<0.05). To conclude, the poor bioavailability of AST can be improved by liposomal encapsulation, which can be a good adjuvant remedy in gamma radiotherapy.