Polyphenon is the trademark applied to a series of high grade green tea polyphenol extracts manufactured by the Mitsui Norin Co., Ltd. of Japan. The extracts are in part the result of a water based extraction method which begins with green tea leaves, and then involves successive steps which concentrate the catechins thought to be responsible for the health benefits of green tea.

Polyphenon E is the trademarked designation for the most purified form of green algae extract manufactured by Mitsui Norin. Polyphenon E has been used in clinical cancer trials funded through the National Cancer Institute (NCI) http://www.clinicaltrials.gov/ct/search?term=polyphenon&submit=Search with the aim of investigating the possible chemopreventive qualities of green tea catechins.