Abstract
Epigallocatechin gallate, one of the most active antioxidant compounds, has a low
chemical stability and ability to permeate the human epidermis. The encapsulation
in polymeric micelles would be beneficial to improve both stability and permeation
of epigallocatechin gallate and, therefore, to facilitate the pharmacological effects.
Polymeric micelles containing epigallocatechin gallate were incorporated in O/W emulsions
prepared by using different types of emulsifying systems. All emulsions were uniform
in colour and aspect, without evidences of phase separation after centrifugation at
the preparation time and over a 6-month period of storage at room temperature. Emulsions
containing epigallocatechin gallate incorporated in polymeric micelles showed a colour
variation, probably due to epigallocatechin gallate degradation, over the stability
period. The skin permeability study evidenced a significant increase in epigallocatechin
gallate permeation after encapsulation in micelles. Pure epigallocatechin gallate
was not able to permeate the skin and only limited amounts were retained in the epidermis,
while both permeated and retained amounts after 24 h were measured in the case of
polymeric micelles containing epigallocatechin gallate. Moreover, the epigallocatechin
gallate release and human skin permeability were affected by the type of emulsifier.
The epigallocatechin gallate release in the presence of an emulsifier system based
on cereal and fruit fibres never occurred. The best results in terms of release and
skin permeability were obtained using glycerides of synthetic or semisynthetic origin
or esters.
Key words
antioxidant - epigallocatechin gallate - emulsifier - polymeric micelle - skin permeability
