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The tannin compounds are widely distributed in many species of plants, where they play a role in protection from predation (acting as pesticides) and might help in regulating plant growth. [1] The astringency from the tannins is what causes the dry and puckery feeling in the mouth following the consumption of unripened fruit, red wine or tea. [ 2 ]
Tannic acid can be applied to woods low in tannin so chemical stains that require tannin content will react. The presence of tannins in the bark of redwood (Sequoia) is a strong natural defense against wildfire, decomposition and infestation by certain insects such as termites. It is found in the seeds, bark, cones, and heartwood.
The most abundant polyphenols are the condensed tannins, found in virtually all families of plants. Larger polyphenols are often concentrated in leaf tissue, the epidermis, bark layers, flowers and fruits but also play important roles in the decomposition of forest litter, and nutrient cycles in forest ecology.
The tannin causes the hide to become supple, less affected by water and more resistant to bacterial attack. [141] At least 120 drugs come from plant sources, many of them from the bark of trees. [142] Quinine originates from the cinchona tree and was for a long time the remedy of choice for the treatment of malaria. [143]
Substances may be excreted to the surface of the plant or into intercellular cavities or canals. Some of the many substances contained in the secretions are not further utilized by the plant (resins, rubber, tannins, and various crystals), while others take part in the functions of the plant (enzymes and hormones).
Phytochemicals are chemicals of plant origin. [1] Phytochemicals (from Greek phyto, meaning "plant") are chemicals produced by plants through primary or secondary metabolism. [2] [3] They generally have biological activity in the plant host and play a role in plant growth or defense against competitors, pathogens, or predators. [2]
Chestnut tannin is obtained by hot-water extraction of chipped wood. It is an ellagic tannin and its main constituents are identified by castalagin (14.2%) and vescalagin (16.2%). [113] [114] It has a naturally low pH value, relatively low salts content, and high acids content. This determines its astringency and its capability to fix raw hides.
Tara tannin derivatives are being proposed as antifouling against marine organisms that can grow on ship hulls. [11] Those tannins are of the hydrolysable type. Gallic acid is the main constituent of tara tannins (53%) and can be easily isolated by alkaline hydrolysis of the plant extract. [12] Quinic acid is also a constituent of the tara ...