Characterization and bioavailability of liposomes containing a ukon extract

In order to use liposomes as an efficient carrier of functional food materials, liposomes encapsulating a ukon extract (LUE) were prepared by the mechanochemical method under different conditions, and were physico-chemically and biochemically characterized. After a homogenization treatment, the size of LUE decreased with decreasing concentration of the extract from 10 to 2.5 wt %, but did not decrease below 570 nm. LUE were thus subjected to microfluidization. The LUE solutions obtained from less than 5 wt % of the extract remained well dispersed for at least 14 d, whereas those from 10 wt % showed phase separation. With 5 wt % of the extract, the size of LUE obtained at an inlet pressure of 100 MPa was smaller than that obtained at 20 MPa, and reached below 180 nm. Under optimal conditions, resulting LUE was confirmed to be small unilamellar vesicles (SUV) with a diameter of approximately 100 nm by freeze-fracture electron microscopy (FFEM). When used for treating simulated gastric and intestinal fluids, LUE obtained by microfluidization showed a 2-fold higher residual rate of curcumin than the uncapsuled extract itself. The bioactivity of LUE was further examined for its suppressive effect on carbon tetrachloride (CCl(4))-induced liver injury by using mice. Orally administrated LUE at a dose of 10 mg/kg as the extract had a much higher suppressive effect on the serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels, compared to the uncapsuled extract at a dose of 33 mg/kg.