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Pharmacology of Veterinary Herbal Medicine (PHA-151) 3 rd Lecture. Dr Khaled Abo EL-Sooud Prof. of Veterinary Pharmacology Faculty of Vet. Med. Cairo University. TANNINS. Are bioactive phenolic compounds of high molecular weight. widely distributed in many species of plants
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Pharmacology of Veterinary Herbal Medicine (PHA-151) 3rd Lecture Dr Khaled Abo EL-Sooud Prof. of Veterinary Pharmacology Faculty of Vet. Med. Cairo University
TANNINS • Are bioactive phenolic compounds of high molecular weight. • widely distributed in many species of plants • play a role in protection from predation, and perhaps also as pesticides, and might help in regulating plant growth.
TANNINS • Tannins are soluble in water and alcohol • found in the root, bark, stem and outer layers of plant tissue. • They are acidic in reaction and the acidic reaction is attributed to the presence of phenolics or carboxylic group • They form complexes with proteins, carbohydrates and alkaloids.
TANNINS • Tannins are divided into hydrolysable tannins (HT) • condensed tannins (CT) and phlorotannins (PT). • The first 2 groups are found in terrestrial plants whilst PT occur only in marine brown algae • Hydrolysable tannins, as theaflavins (from tea), genistein and glycitein • upon hydrolysis, produce gallic acid or ellagic acid and depending on the type of acid produced, the hydrolysable tannins are called gallotannins or egallitannins. • On heating, they form pyrogallic acid.
TANNINS Condensed tanninsare oligomeric or polymeric flavonoids consisting of flavan-3-ol units that include catechin, epicatechin, gallocatechin and epigallocatechin. Unlike HT, only strong oxidative and acidic hydrolysis can depolymerize the CT structures that are also not susceptible to anaerobic enzyme degradation
TANNINS Hydrolysable tannins are used as astringent and antiseptic and this activity is due to presence of the phenolic group. Dry sensation in the mouth. The tannins in some teas and red grape
TANNINS ASTRINGENTScause constriction or contraction of mucous membranes and exposed tissues due to precipitation of cell proteins and are often used internally to reduce discharge of blood serum and mucous secretions used for the treatment of diseases like leucorrhoea, rhinnorhoea and diarrhea, skin bleedings and transudates, sore throat, haemorrhages, and peptic ulcers.
TANNINS Externally applied astringents, which cause mild coagulation of skin proteins, dry, harden, and protect the skin. People with acne are often advised to use astringents if they have oily skin. Mild astringents relieve such minor skin irritations as those resulting from superficial cuts; allergies; insect bites; and fungal infections, such as Tinea pedis
Tinea pedis Acne
Antimicrobial property The antimicrobial activities of tannins due to the toxicity of tannins to bacteria, fungi and yeasts. The mechanisms include inhibition of extracellular microbial enzymes, Stop growth of microbial cells Generally, anti-microbial activity of tannins against Gram-positive bacteria has been reported to be greater than against Gram-negative bacteria cell membrane of bacteria
Anthelmintic property The anti-parasitic effects of various tannins observed in in vitro studies have also been confirmed in numerous in vivo studies involving in sheep and cattle against nematodes.
Use of tannins in ruminants Condensed tannins at low to medium concentrations benefit ruminant production efficiency because CT reduce protein degradation in the rumen, increase the amount of dietary protein reaching small intestine for absorption
Anti-nutritional in monogastric animals Unlike for ruminants, tannins have traditionally been considered as ‘anti-nutritional’ factors in monogastric nutrition with negative effects on feed intake, nutrient digestibility and production performance. Therefore, it is almost a common practice in feeding industry to minimize the use of tannin-containing feed in swine and poultry diets or to take measures to reduce their dietary concentrations if such feed are used.
Edible plants contain tannins Pomegranates Strawberriescontain both hydrolyzable and condensed tannins Nuts that can be consumed raw, such as hazelnuts, and walnuts, contain high amounts of tannins SpicesCloves, tarragon, cumin, thyme, vanilla, and cinnamon all contain tannins Chocolate Tea
Test for Tannin 0.1gm of plant material was taken in test tube and 3ml of butanol-HCL reagent (95ml of n-butanol and 5ml of concentrated HCL) was added to it. Test tubes were plugged with cotton and were heated on boiling water bath for an hour. Appearance of pink color was taken as presence of tannin
