What is catechin?

Catechins may also be called flavan-3-ols, which represent a relatively small group of the flavonoid class of natural products, while proanthocyanidins are defined as oligomers and polymers of catechins, in which catechins units are connected through carbon-to-carbon linkages.

Flavan-3-ols are colorless compound. Epicatechin is an example of a flavan-3-ol. The green tea polyphenols are composed of seven different kinds of catechin derivatives including: catechin; epicatechin; gallocatechin; epigallocatechin; epicatechin-3-gallate; gallocatechin-3-gallate; and epigallocatechin-3-gallate.

Green tea catechins exhibit powerful antioxidant, antitumor and anticancer damage.
What is catechin?