Catechine

Catechin is a natural phenolic compound in the flavanol class. It occurs in a wide range of plants, most notably Camellia sinensis (tea), Theobroma cacao (cocoa), grapes, and berries. Catechin exists as two enantiomers, (+)-catechin and (-)-catechin, and can be incorporated into larger flavanol polymers called proanthocyanidins or condensed tannins, which contribute to plant defense and to the sensory properties of foods.

Chemically, catechin has the molecular formula C15H14O6 and a molecular weight of about 294.27 g/mol. It contains several hydroxyl groups, which confer antioxidant activity and influence its reactivity and solubility. In nature, catechin can be found in free form or bound within larger polyphenolic structures, and it can be extracted using standard phytochemical methods.

Biosynthesis and role in plants: Catechin is produced via the flavonoid biosynthesis pathway from phenylalanine. It serves as a monomer for proanthocyanidins, a class of tannins that contribute to astringency and play a protective role against herbivores and pathogens. In plants, the enzyme leucoanthocyanidin reductase (LAR) can reduce leucoanthocyanidins to catechin, while anthocyanidin reductase (ANR) contributes to the related unit, epicatechin, providing diversity in tannin polymers.

Uses, nutrition, and safety: In foods and beverages, catechin contributes to flavor, color, and mouthfeel, and is a major contributor to the antioxidant activity of green tea. Dietary intake is studied for potential health effects, including cardiovascular benefits and anti-inflammatory activity; results are mixed and depend on dose and bioavailability. Catechin supplements are available, often as part of green tea extracts, but high-dose preparations have been linked to rare cases of liver toxicity. Catechin is generally regarded as safe in ordinary dietary amounts and is not approved as a medicinal drug.