Comparison of the antioxidant and transmembrane permeative activities of the different Polygonum cuspidatum extracts in phospholipid-based microemulsions.

The main purpose of this study was to investigate the transmembrane permeability of polyphenol-containing Polygonum cuspidatum extracts (PCE) encapsulated in phospholipid-based o/w microemulsion system. First, preparations of several PCEs using solid- or liquid-phase extraction or a combination of both, as well as evaluation of their antioxidant activities, were conducted and compared. In the antioxidant study, results indicated that PC-1 with the least extraction process exhibited the best antioxidant activity. By comparing the permeability coefficient (K(p)) among all tested PCEs in microemulsions (ME-PCs), ME-PC1 also possessed the largest permeability coefficients of both resveratrol and emodin. In addition, comparison of the transmembrane permeability of several polyphenol-encapsulated microemulsions showed that resveratrol had the most competitive advantage in the microemulsion formula for the control-release process. Taken together, it can be concluded that the matrix removed from the solid-phase extraction in PC-1 not only possesses antioxidant activity but also acts as an enhancer in transmembrane permeation. The structure specificity of the polyphenol plays important roles in the mechanism of the transmembrane permeation process. These findings might provide scientific evidence for the value of developing polyphenol-containing PCEs as nutraceuticals and cosmoceutical products.