Catechins are natural antioxidants, commonly found in green tea; however their use in cosmetic products has been limited because they do not permeate the skin well.
Therefore, researchers in Thailand evaluated the cutaneous absorption of catechins from an extract of green tea and from a green tea extract–loaded chitosan microparticle.
The catechin skin metabolism was also examined, and the study was published in the International Journal of Cosmetic Science.
The researchers performed an in vitro skin permeation study along with a study into green tea metabolism, examining the difference between the normal tea extract and the one loaded with the chitosan microparticle.
Significantly improved permeation
The study results suggest that chitosan microparticles significantly improve the ability of catechins to permeate skin.
The tea plant contains several kinds of catechins or flavonoids, often divided into two classes; astringent galloyl catechins and free, or non-galloyl, catechins.
“This study clearly indicates that non-galloyl catechins, epicatechin (EC) and epigallocatechin (EGC) are able to penetrate into the skin more easily than galloyl catechins, epigallocatechin gallate (EGCG) and epicatechin gallate (ECG),” said the report.
Skin enzymes also influenced the amount of catechins detected in each skin layer. Chitosan microparticles effectively prevent enzymatic changes of the catechins, allowing them to better permeate the skin, according to the study.
This could hold potential for future uses in skin care creams, as the study showed the chitosan microparticles to be promising carriers for enhancing the skin permeation.
The study was supported by a grant from the National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, Thailand, and Center of Excellence for Innovation in Chemistry (PERCH-CIC).
Wisuitiprot, W., Somsiri, A., Ingkaninan, K. and Waranuch, N. (2011), In vitro human skin permeation and cutaneous metabolism of catechins from green tea extract and green tea extract–loaded chitosan microparticles. International Journal of Cosmetic Science, 33: 572–579. doi: 10.1111/j.1468-2494.2011.00673.x