ellagitanniner

Ellagitannins (ellagitanniner in Swedish) are a class of hydrolyzable tannins, polyphenolic compounds in which hexahydroxydiphenic acid (HHDP) units are esterified to a sugar core, usually glucose. The HHDP groups may lactonize to ellagic acid upon hydrolysis, yielding ellagic acid and related derivatives. The number and arrangement of HHDP units give rise to a variety of structures, including monomeric, dimeric, and larger oligomeric forms. Prominent examples include punicalagin and punicalin from pomegranate, vescalagin from oak, and agrimoniin from diverse plants.

Ellagitannins occur in a range of edible and woody plants. They are found in pomegranates, various berries (such as raspberries and strawberries), nuts, tea, and in wood and bark of oak and chestnut trees. Their levels in foods can influence taste by contributing astringency and brownish color, especially in aged wines and dried fruits.

In terms of metabolism and health, ellagitannins are typically not absorbed in their intact form. They are hydrolyzed in the gut to ellagic acid and to HHDP derivatives, and the HHDP units may further metabolize via gut microbiota into a range of urolithins, which can be more readily absorbed. Ellagitannins exhibit antioxidant activity in vitro and have been studied for potential anti-inflammatory, anti-cancer, and neuroprotective effects, though evidence from clinical studies remains inconclusive and effects are likely context-dependent.

Due to their tannin character, ellagitannins contribute to astringency and can interfere with mineral absorption when consumed in large amounts. They are generally regarded as natural components of foods and are also studied for use in food processing and nutraceuticals.