Tannic acid, astringency

Astringents are designed to dry the skin, denature skin proteins, and tighten or reduce the size of pore openings on the skin surface. These products can have antimicrobial effects and are frequendy buffered to lower the pH of skin. They are perfumed, hydro-alcohoHc solutions of weak acids, such as tannic acid or potassium alum, and various plant extracts, such as bitch leaf extract. The alcohol is not only a suitable solvent but also helps remove excess sebum and soil from the skin. After-shave lotions generally function as astringents. 

Astringents such as tannic acid (home remedy black tea) or metal salts precipitate surface proteins and are thought to help seal the mucosal epithelium. Protein denaturation must not include cellular proteins, for this would mean cell death. Although astringents induce constipation (cf AP salts, p. 166), a therapeutic effect in diarrhea is doubtful. 

Naish, M., Clifford, M.N., and Birch, G.G., Sensory astringency of 5-O-caffeoylquinic acid, tannic acid and grape seed tannin by a time-intensity procedure. J. Sci. Food Agric. 61, 57, 1993. 

In dentistry, when astringents and antiseptics are used to harden and dry tissues of the pulp and root canal so that the tissues are resistant to infection, they are termed as mummifying agents. It is used in certain dental procedures when it is not possible to completely remove the pulp and contents of root canal. For this, generally a combination of various mummifying agents are used in the form of paste or semi-liquid preparation like tannic acid glycerine. 

FIGURE 7. Bitter response plateaus while astringency (drying) response continually increases on repeated exposure to tannic acid. [Reproduced from ref. 40 by permission of Oxford University Press]... 

Macrocarpium officinalis (Sieb. et Zucc.) Nakai Shan Zhu Yu (fruit) Tannic acid, resin, tartaric acid, comin, gallic acid, malic acid.60 A tonic, astringent, diuretic, antillithic, anthelimintic, febrifuge. 

N.A. Comus florida L. Verbenalin, saponins, tannins, resin, gallic acid, malic acid, tartalic acid, tannic acid.100-123 An astringent, tonic, and hemostatic. 

This contains a considerable quantity of tannic acid as well as cathartic principles. The astringent action predominates with smaller doses (0.05 to 0.01 g), and these are used as astringent bitters in gastric catarrh and in diarrhea. Larger doses (1 to 5 g) are laxative with little colic. They may be employed in chronic constipation, but the astringent action makes it inferior to cascara. It may cause skin eruptions. 

Kino-tannic and kinovo-tannic acids give to bark its peculiar and powerful astringent qualities. They have not been fully studied. 

Calamine and astringents (aluminium acetate, tannic acid) may help. Local anaesthetics do not offer any long-term solution and since they are liable to sensitise the skin they are best avoided lignocaine is least troublesome in this respect. Topical doxepin... 

Products containing combinations of constituents with local anaesthetic and analgesic effects, such as lidocaine, choline salicylate and phenol, counterirritants such as ammonia solution and menthol, and astringents such as zinc sulphate and tannic acid, are marketed to reduce discomfort and promote faster healing of sores while the infection takes its course. Some are formulated with alcoholic bases, which may have a drying effect on sores and speed up healing. The bland cream bases of some products may have a soothing effect. 

This is the product of a reaction between tannic and boric acids. Tannic acid is an astringent boric acid is an antifungal. The only preparation is a complex one combined with salicylic acid, available over the counter as Phytex. 

Tannins—Tannic acid——322.—Quite a number of different substances of vegetable origin, principally derived from barks, leaves, and seeds. Tliey are amorphous, soluble in water, astringent, capable of precipitating albumen, and of forming imputrescible compounds with the gelatinoids. They are, with one possible exception, glucosides. 

Tannic Add also called Tannin. Pare tannio acid is sohd, unciystallizable, white, or slightly yellow strongly astringent, but without bitterness very soluble in water, less so in alcohol and ether, and insoluble in fixed or volatile oils. Its solution reddens litmus. T7ith the bases tannic acid forms... 

MERCURIC BICHLORIDE (7487-94-7) HgClj Contact with acids or acid fumes evolves chloride and mercury vapors. Possible violent reaction with chlorine nitrate, sodium acetylide. Incompatible with albumin, alkalis, alkaloid salts, anhydrous ammonia, antimony, arsenic, borax, bromides, carbonates, chloric acid, copper, formates, gelatin, hydrozoic acid, infusions of cinchona, iron, lead and silver salts, lime water, light metals, methyl isocyanoacetate, oak bark or senna, phosphates, potassium, reduced iron, sodiiun, sodium peroxyborate, sulfides, sulfites, tannic acids, trinitrobenzoic acid, urea nitrate, vegetable astringents. Decomposed by sunlight. On small fires, use water spray, fog, foam, dry chemical powder, or CO2 extinguishers. 

Incompat Acetanilide, antipyrine, chlorates, hypophos-phites, iodides, mercury salts, permanganate, sulfites, tannic acid, vegetable astringent decoctions, infusions Or tinctures. 

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