Hydrolyzable Tannins: Polymeric derivatives of GALLIC ACID that are esters of a sugar.Tannins: Polyphenolic compounds with molecular weights of around 500-3000 daltons and containing enough hydroxyl groups (1-2 per 100 MW) for effective cross linking of other compounds (ASTRINGENTS). The two main types are HYDROLYZABLE TANNINS and CONDENSED TANNINS. Historically, the term has applied to many compounds and plant extracts able to render skin COLLAGEN impervious to degradation. The word tannin derives from the Celtic word for OAK TREE which was used for leather processing.Theaceae: A plant family of the order THEALES, subclass Dilleniidae, class Magnoliopsida, best known for CAMELLIA SINENSIS, which is the source of Oriental TEA.Terminalia: A plant genus of the family COMBRETACEAE. Members contain arjunin, an ellagitannin (TANNINS).Plant Extracts: Concentrated pharmaceutical preparations of plants obtained by removing active constituents with a suitable solvent, which is evaporated away, and adjusting the residue to a prescribed standard.Proanthocyanidins: Dimers and oligomers of flavan-3-ol units (CATECHIN analogs) linked mainly through C4 to C8 bonds to leucoanthocyanidins. They are structurally similar to ANTHOCYANINS but are the result of a different fork in biosynthetic pathways.Astringents: Agents, usually topical, that cause the contraction of tissues for the control of bleeding or secretions.