Catechins - natural organic matter contained in the leaves of tea, the vine, in the skin of lemons and oranges, immature, walnut, black currant, dog-rose. Crystals, astringent taste, soluble in hot water, ethyl alcohol. Catechins have the properties of vitamin P, increases elasticity of the walls of capillaries and are used to treat disorders of the permeability of capillaries. Catechins contribute to the body's use of ascorbic acid.