Enhancement of catechin skin permeation via a newly fabricated mPEG-PCL-graft-2-hydroxycellulose membrane

Green tea extracts largely consist of anti-oxidative/anti-inflammatory catechins such as (-)-epigallocatechin gallate. Orally administered catechins are metabolized in the gastrointestinal tract and liver, subsequently incurring low bioavailability. This study attempts to improve the bioavailability of catechin by using mPEG-PCL-graft-2-hydroxycellulose (mPEG-PCL-g-HEC) porous membrane as a penetration matrix for skin delivery of catechins. The green tea-extracted catechin was obtained based on the partition difference in two phases of solvents. In vitro permeation tests using a Franz diffusion cell system indicated that the mPEG-PCL-g-HEC membrane with a loading content of the catechins of 1.5mg/cm² significantly enhanced the permeation of the catechins up to 0.84mg/mL in the receptor of Franz cell for a period of 48h, whereas the permeated catechins through HEC membrane was only 0.04mg/mL. Moreover, a comparative experiment of the oral and transdermal administrations was conducted to measure the delivered catechins in plasma in Wistar rats. In the oral administration where free catechin was given, the catechin AUC was 34.22±1.51μgh/mL and C_max was 22.7±1.29μg/mL, respectively. Conversely, in the transdermal administration using catechins-loaded E₅₀C₃₆-g-HEC membranes, the catechin AUC of 356.24±3.24μgh/mL and C_max of 19.03±0.75μg/mL was obtained. Furthermore, a higher catechin AUC of E₅₀C₃₆-g-HEC membrane than that of E₅₀-C₈₄-g-HEC membrane presented a role of the permeation enhancer to the amphiphilic polymer grafted to the cellulosic material. Therefore, this study showed the potential use of amphiphilic polymer mPEG-PCL in controlling the delivery of catechins via skin.