Ellagic acid is found in strawberries and blackberries as a derivative from gallic acid and as an ellagitannin (hydrolyzed tannin). It works both as an anti-oxidant and as a potential ingredient for preventing the formation of spots and freckles after sun exposure and sunburn as it might be tyrosine inhibitor, which plays a role in melanin synthesis. It may reduce the destruction of collagen, and help regenerate skin cells, which can reduce the signs of aging.
It is a type of hydrolyzable tannin – one that, when combined with a weak acid or base, will produce a carbohydrate and phenolic acid. (Wikipedia)