Extract from the minimally processed buds and leaves of green tea. There is research showing that white and green teas have the highest concentration of antioxidant properties (via their polyphenol and flavonoid content) of all teas. However, even though tea flavonoids are effective antioxidants, it is unclear to what extent they increase the antioxidant capacity of humans.
It appears that white and green teas have similar amounts of the polyphenol epigallocatechin-3-gallate (EGCG), which is the main antioxidant in tea. The conclusion is that white and green tea have nearly identical antioxidant activity, and both are great antixoidants to look for in skincare products.
Reference for this information:
Biochemical and Biophysical Research Communications, August 2002, pages 584–588