Microemulsions can improve skin penetration of lycopene

Lycopene has particularly strong antioxidant properties, but, according to the study published in the Journal of Pharmaceutical Science, integrating it into topical formulations is challenging.

The compound, found in red coloured fruits such as tomatoes, is strongly lipophilic (fat liking rather than water liking) which means it is insoluble in water as well as a number of oils used in cosmetics formulations, according to the study.

In addition, its lipophilic nature could also affect its ability to penetrate into the deeper layers of the skin, as it may be retained in the skin’s outermost layers, the stratum corneum.

According to the recent study, microemulsions could provide an answer to these formulation challenges by enhancing the delivery of the compound and therefore increasing the tissue antioxidant activity.

Capric and caprylic acids were used as the oil phase in the microemulsion, which also contained a surfactant blend of propylene glycol, and the properties of an emulsion containing the mono/diglycerides (ME-MG) of the acids was compared to that containing triglycerides (ME-TG).

Mono/diglycerides most effective​

Both of the microemulsion solutions improved skin penetration of the lycopene in comparison to the control (experiments were performed on porcine ear skin) but it was ME-MG that was the most effective, according to the results.

In addition, the reduction of skin electrical resistance was higher after treatment with the mono/diglyceride microemulsions than with the triglyceride versions. This, the authors suggested, reflects a higher ability for the mono/di forms to disrupt the barrier function therefore improving the penetration of the ingredient.

The effect of ascorbic acid was also investigated on skin penetration of the lycopene.

Although the presence of ascorbic acid increased the concentration of lycopene in the skin, the effect was significant with the mono/di form. This could be due to the ability of ascorbic acid (also with strong antioxidant properties) to protect and improve the stability of the lycopene.

“This association ​[combining lycopene with other antioxidants for protection] may be beneficial to improve lycopene stability and increase its concentration in the skin,”​ the authors wrote.

The researchers conclude that microemulsions containing medium chain glycerides (especially mono- and diglycerides) can promote the cutaneous delivery of lycopene and improve the antioxidant activity of the skin.

Source: journal of Pharmaceutical Sciences
Vol 99, No 3, March 2010,
Topical Delivery of lycopene using microemulsions: enhance skin penetration and tissue antioxidant activity
Luciana B. Lopes, Hillary Vendewall, Hsin T. Li, Vijay Venugopal, Hsin K. Li, Stan Naydin, Jaclyn Hosmer, Mark Levendusky, Haian Zheng, M. Vitória L.B. Bentley, Robert Levin, Martha A. Hass