Ellagic acid is a natural polyphenol produced by plants from the hydrolysis of tannins (R). It is found in a wide variety of fruits and nuts (R), including pomegranates (R, R), strawberries (R, R), muscadine grapes (R, R, cranberries (R), blueberries (R), blackberries (R, R), raspberries (R, R), pecans (R), walnuts (R) and honey (R, R, R). Among fruits consumed in Brazil, jabuticaba, grumixama and cambuci have the highest total contents of ellagic acid (R).
Ellagic acid has also been found in oak leaves (R), chestnut tree leaves (R) and bark (R), and in Phellinus linteus (R), a type of mushroom used in traditional medicine in Asia (R).
Ellagic acid can also be produced the action of fungi such as Aspergillus oryzae (R, R, R) and Aspergillus niger (R) or microbial enzymes (R, R) on ellagitannins from acorn fringe (R, R, R), acorn cups (R) or pomegranate residue (R).
On its own, ellagic acid has poor solubility and low permeability, making formulation design difficult. Fortunately, niosomes appear to be good carriers for the dermal delivery of ellagic acid. While ellagic acid in solution cannot penetrate to the viable epidermis and dermis, ellagic acid from ellagic acid-loaded niosomes is capable of penetrating the skin up to a depth of 120 µm, where the dermis resides (R). Similarly, ellagic acid was delivered to the viable epidermis and dermis when it was entrapped in nanoemulsions (R).