Lycopene has been demonstrated to be effective against diseases such as skin cancer, prostate cancer and cardiovascular disease. However, questions over its clinical use remain as it has an extremely low bioavailability. To combat this, researchers have prepared stable lycopene micelle and lycopene chylomicron formulations by employing a microemulsion technique. The samples show a narrow particle size distribution and high encapsulation efficiency: 78% and 80%, respectively.

Determining bioavailability

To determine the absolute bioavailability, a pharmacokinetic study was performed by administering male Sprague-Dawley rats with lycopene micelles or lycopene chlylomicrons via oral and intravenous routes. Blood samples were collected at periodic time intervals up to 72 hours and analysed for lycopene and its precursors, phytoene and phytofluene, both of which are biologically important to human health.

Size-dependant systemic exposure

The researchers found that a shorter time is required to achieve the maximum concentration of lycopene in the blood on administration of the micelles compared with the chylomicrons. This implies that there was greater systemic exposure of the lycopene micelles, probably due to their much smaller particle size: micelles have an average particle size of 7.5 nm compared with the 131.5 nm of chylomicrons.

Shape-dependant bioavailability

Lycopene chylomicrons showed a higher oral bioavailability than lycopene micelles as they provided better protection for the lycopene, phytoene and phytofluene due to a thick outer layer visualized under the transmission electron microscope.

Consequently, both size and shape should be taken into account for oral bioavailability evaluation. With intravenous injection, lycopene micelles should be more important than lycopene chylomicrons for future biomedical application.

More information can be found in the journal Nanotechnology 25 155102

Further reading

Self-assembled micelles for honokiol delivery (June 2010)
Doxorubicin-loaded micelles increase drug activity and lower systemic toxicity (Mar 2011)