Tannins : A S econdary M etabolite Presented by : Dr. Shefali Rana MD 1 st year Deptt . Of Dravyaguna Vigyana R.G.G.P.G.Ayu . College, Paprola
Contents - What is Tannin ? Classification of Tannin Properties of Tannin Identification test Pharmacological action of Tannin General method of Extraction Drugs containing Tannin Side effect of Tannin List of some drugs containing tannin according to P.V. Sharma vol. II Conclusion
INTRODUCTION
What is TANNIN ? The name ‘tannin’ is derived from the French word ‘ tanin ’ (tanning substance) and the term ‘tannin’ was first applied by Seguin in 1796 to denote – “ A Substances present in plant extracts which were able to combine with protein of animal hides, prevent their decaying and convert them into leather ”. Tannin are astringent, poly-phenolic, secondary metabolites that are bind to and precipitate proteins and various other organic compounds including amino acids and alkaloids.
Tannins are naturally occurring complex organic compounds possessing nitrogen free polyphenols of high molecular weight which generally have astringent properties. They form colloidal solution with water giving acid reactions . Because of astringent nature of tannins, that they precipitate proteins and help to resistant the effect of Heat, water enzymatic attack in plants . When applied on a wound or injury, tannins form a protective coating so as to prevent external irritation and thus promote healing .
Occurrence Tannins are distributed in species throughout the plant kingdom. They are commonly found in both gymnosperms and angiosperms . Mole studied the distribution of tannin in 180 families of dicotyledons and 44 families of monocotyledons . The best known families contain tannin are : Aceraceae Anacardiaceae Moraceae Burseraceae Combretaceae Dipterocarpaceae Fagaceae Myricaceae Fabaceae In dicots
Najadaceae , Liliaceae , Poaceae and Typhaceae in Monocot . To the family of the oak, Fagaceae , 73% of the species tested contain tannin. For those of acacias, F abaceae , only 39% of the species tested contain tannin. Among Solanaceae rate drops to 6% and 4% for the Asteraceae. Some families like - Boraginaceae , Cucurbitaceae, Papaveraceae contain no tannin species.
Cellular localization of tannin in plants Tannins are found in leaf, bud, fruit, seed, root, and stem tissues . Tannins are manufactured by a chloroplast-derived organelle the T annosome . Tannins are mainly physically located in the vacuoles of plants . After the tannins are created, the T annosome is encapsulated in a membrane , allowing the structure to bud off from the chloroplast and to be shuttled to a plant vacuole for safe storage. These storage sites help to keep tannins active against plant predators , but also keep tannins away from affecting plant’s own metabolism while the plant tissue is alive; it is only after cell breakdown and death that the tannins are active in metabolic effects .
Localization of tannin in different parts of plants and its role - Different parts of the plant contain different amounts of tannin –
Other functions are play role in the physiology of 1. development and maturation of the seeds and 2. in the activation of the nodulation gens which favor the fixation of nitrogen in the plants and 3. in the attraction of pollinating insects. Plant part Localisation of tannin Function Leaf tissues most common in the upper epidermis. However, in evergreen plants, tannins are evenly distributed in all leaf tissues. They serve to reduce palatability and, thus, protect plant against predators. Buds most common in the outer part of the bud As protection against freezing or heat
How tannin protect plants : T annins are essential products for plant defense , and they provide plants with a chemical mechanism with which to combat pathogens and herbivores. But how??????? Because tannins are so Astringent , most herbivorous predators avoid to consume them. Moreover, if any herbivorous predator persistent enough to eat tannin-rich plants, the tannins will biochemically target digestive enzymes and inhibit digestion , sometimes to the extent that the animal is killed .
classification
Classification of Tannins True Tannins On the basis of their molecular weight Hydrolysable Tannins Condensed Tannins C omplex tannins Ellagitannins Gallitannins Pseudotannins
On the basis of molecular weight - True tannins These are complex phenolic compounds of high molecular weights ranging from about 1000 to 5000 daltons or more. They display the general properties of tannins and precipitated by gelatin in 1% solution. True tannins can be sub-classified into – Hydrolysable tannins, Condensed tannins and Complex tannins.
Pseudotannins : Pseudotannins are simple phenolic compounds of lower molecular weight than true tannin. They do not respond to the tanning reaction of Goldbeater’s skin test . But may , under certain conditions, e.g. in concentrated solutions, give precipitates with gelatin. Gallic acid, Chlorogenic acid, or the simple phenolics such as catechin are pseudo-tannins which are abundantly found in plants, especially in dead tissues and dying cells . Examples are - Catechins : Catechu, cocoa, etc. Chlorogenic acid: Coffee and N ux -vomica
On the basis of hydrolysation - 1. Hydrolysable tannins: HTs are formed from several molecules of phenolic acids such as gallic and hexa -hydroxyl- diphenic acids which are united by ester linkages to a central sugar (mainly glucose) molecule. These tannins are hydrolyzed by acids, or enzyme ( tannase ) and produce gallic acid and ellagic acid. They were formerly known as pyrogallol tannins , because on dry distillation gallic acid and similar components are converted into pyrogallol . Two types of hydrolysable tannins are gallitannins and ellagitannins .
Further two more types of hydrolysable tannins - ELLAGI-TANNIN : The ellagitannin is characterized by hexa hydroxyl diphenyl ester group. Ellagitannin yields ellagic acid on hydrolysis I n addition to other phenolic compounds, namely chebulic acid, chloro-ellagic acid etc. Sources for ellagitannin are myrobalans , pomegranate, eucalyptus leaves etc . GALLO-TANNIN : Gallotannin is considered to be hydrolysable type since it yields gallic acid on hydrolysis . The gallotannin , also called tannic acid, is obtained from plant galls . Source- rhubarb, cloves, red rose petals, bearberry leaves, Chinese galls, Turkish galls
2. Condensed tannins: Unlike hydrolysable tannins, these are not readily hydrolyzable to simpler molecules and they do not contain a sugar and consisting of coupled flavan-3-ol ( catechin ) units . They are also called P ro- anthocyanidins , because they are decomposed to anthocyanidins in heated ethanol solutions. On treatment with acids or enzymes they are converted into red water- insoluble compounds CALLED – Phloba-phens . On dry distillation , condensed tannin produce catechol. These tannins are called as catechol tannins . These tannins are found in cinchona bark, male fern, grapes seeds, tea leaves and wild cherry bark, etc. T hey produce green colour with ferric chlorides.
3. Complex tannins Complex tannins consist of a gallotannin or ellagitannin unit along with a catechin unit . These represent a group of tannins that are biosynthesized from both hydrolysable tannin and condensed tannin OR In simple words - These tannins are mixtures of both, hydrolysable and condensed tannins. Example – Acutisimin A , the usual synthetic representative of the complex tannins .
Physical properties of tannin Color : Pale yellow to light brown-red substances Taste : Puckering taste or astringent taste. State : Non-crystalline. Solubility: Completely Soluble in water, alcohol, dilute alkalis, glycerol and acetone. S paringly soluble in chloroform, ethyl acetate and other organic solvents.
Chemical properties Precipitation - Tannins have ability to precipitate solutions of - Gelatin Alkaloids Glycosides Heavy metals Proteins M olecular weight ranging from 500 to > 20,000 Daltons. Reaction with salts – H ydrolysable tannin + Ferric salt Blue black precipitates Condensed tannin + Ferric salt Brownish green precipitates
Chemical tests for identification Test Procedure Observation Goldbeater's skin test Soak a small piece of goldbeater's skin in 25% HCl ; rinse with distilled water and place in the tannin solution to be tested for 5 min. Wash with distilled water and transfer to a 15 % solution of ferrous sulphate . A brown or black color on the skin denotes the presence of true tannins. Gelatin test Solutions of tannins (about 0.5-1%) precipitate a 1% solution of gelatin containing 10% sodium chloride . White buff colour precipitate. Ferric chloride test Add 5 % ferric chloride solution drop by drop to 2-3 ml of the aqueous extract and observe the color produced. Hydrolysable tannins give bluish-black color and Condensed tannins brownish-green ones.
Test Procedure Observation Phenazone test A mixture of aqueous extract of a drug and sodium hydrogen phosphate is heated and cooled and filtered. A solution of phenazone is added to the filtrate. The precipitate being bulky and often colored Vanilin -hydrochloric acid test Solutions of tannins, added vanillin- hydrochloric acid reagent (Vanillin 1gm, alcohol 10 ml, concentrated hydrochloric acid 10 ml). A pink or red colour is formed Match stick test ( Catechin test) A match stick is dipped in aqueous plant extract, dried near burne r and moistened with concentrated hydrochloric acid and warm near a flame. The matchstick wood turns pink or red colour .
What are free radicals and what they do ? They are oxygen containing molecules with uneven number of electron. To become stable again, they scavenger other stable molecule and steal their electron. – This process called oxidation. The molecules that was attacked and lost its electron is now unstable and become oxidized. And now it will attack other stable molecules. This cause chain reaction and result in oxidation stress which in-turn cause cell to weaken , die or mutate.
Oxidation stress mean distrurbance in balance between production of reactive oxygen species and antioxidant defense .
1 . Anti oxidation activity - Tannin donot function solely as primary antioxidant but function as secondary antioxidant. Several studies have demonstrated tannin ability to scavenge hydroxyl, super-oxide and peroxyl radicals by donating electron to free radical, which helping to restore the body oxidative balance by producing more stable and less radial structure.
Wound healing effect
2. Wound healing properties- Tannins bind to proteins forming cross-linking that tightens and thickens tissues and later to produce a protective layer that can help heal wounds, arrest bleeding and prevent infection . Activate of inflammatory cytokines and growth factors . The growth factors including basic fibroblast growth factor ( bFGF ) , transforming growth factor-beta , and vascular endothelial growth factor .
3. Anti microbial activity Tannins seem to affect bacterial growth in several ways, such as- Tannin ability to pass through the bacterial cell wall up to the internal membrane, interference with the metabolism of the cell, and as a result—their destruction . Unavailability of the substrates required for microbial growth Or direct action on microbial metabolism through inhibition of oxidative phosphorylation .
4. Antiviral activityy
General mechanism of virus life cycle - Invading of parental virus in body Attach to surface of host cell Than intact virus Either penetrate the membrane Or inject the genetic material of virus Enter in cell cytoplasm and release the genetic material from the capsid Transcription of genome of virus to produce viral mRNA Absorption 1. Adsorption 2. Penetration 3. Uncoating 4. Biosynthesis
Translation of viral mRNA in ribosomes in which protein in formed by decoding mRNA . ANTIVIRAL ACTION BY TANNIN - Due to the linkage of tannins on protein surface of viruses or on specific protein receptor of host cells . Through this, adsorption is restricted which eventually restrict virus penetration , its uncoating and further process. After translation, replication of parental genome to make progeny genome Assmebly of newly replicated progeny genome with structural protein to make fully formed progeny virus Release of progeny virus by lysis of host cell from original site to other site in body. 5. Assmeble 6. Release
5. Cardioprotective activity: Tannins have cardioprotective activity via- stabilizing degenerated pericardial tissue by bind to collagen. and inhibition of enzymatic action of enzyme elastase . and reduction of the calcification of aortic wall. Hydrolysable tannins, in particular, reported in a experimental study to have anti-ischemic activity and vaso -relaxant effect.
6. Antidiabetic activity Tannins possess antidiabetic potential- F irstly due to their ability to lower glucose levels by Delaying intestinal glucose absorption Or by the inhibition of α-amylase and α- glucosidase activity A nd secondly by delaying the onset of insulin-dependent diabetes mellitus by providing the antioxidant environment to pancreatic β-cells.
General method of tannin extraction Tannin compounds can be easily extracted by water or alcohol. Plant material Alcoholic extract Ethereal layer Aqueous layer Concentrate and dried Concentrate and dried Subjected to isolation and purification by chromatography Alcoholic extract Alcohol/water Ether
Drugs containing Tannins - Hydrolysable T annin Condensed Tannin H aritaki Bibhitaki Amla Arjuna Ashoka Black catechu Pale catechu B ijak
A . Hydrolysable tannin - 1. Haritaki / Terminalia chebula Synonym – CHEBULIC MYROBALAN Biological source – Fruit of Terminalia chebula Chemical constituent – its fruits are an important source of tannin containing 25-32 percent. Depending upon the geographical source, fruits collected from Chennai, are very rich in tannin. Tannin of haritaki are of pyrogallol type which yield chebulic acid on hydrolysis. During maturation of tree, the amount of tannin decreases, whereas the acidity of fruit increases.
Uses – Myrobalan is used as a Astringent, Anthelminitic , Antioxidant and Tonic. Because of antiseptic and healing properties of tannins, it is used externally in chronic ulcers, wounds, piles. It is one of the drugs of the well-known preparation ‘ Triphala ’. Fine powder of myrobalan is used in dental preparations especially for bleeding gums. Commercially , it is used in dyeing and tanning industry .
2. Bibhitaki / Terminalia belerica Synonym – BELERIC MYROBALAN Biological source – Fruits of Terminalia belerica Chemical constituent – The fruits contain about 20 to 30% of tannins and 40 to 45% water-soluble extractives. It contains colouring matter and its seeds contain non-edible oil. It also contains most of the sugars as reported in myrobalan .
Uses – Bahera is used as an astringent and in the treatment of dyspepsia and diarrhea. T he antiulcer properties of Bibhitaki fruit derived from rich plant compounds like ellagitannin . The goodness of ethanol and tannins extract present in the fruit heal external wounds at a faster rate . Bibhitaki is high in tannin that have beneficial effects on blood sugar levels, insulin sensitivity and body weight.
3. Amalaki / Emblica officinalis - Synonym – Indian gooseberry Biological source – Fruit of Emblica officinalis Chemical constituent – Amla fruit is rich natural source of Vitamin C and contain 5 percent tannin in which two main hydrolysable tannins are Emblicanin A and B, which have antioxidant properties. It is found that vitamin content of dried fruits is not lost due to presence of tannin which retard oxidation of Vitamin C.
Chemical Tests – Alcoholic or aqueous extract of the drug gives blue colour with ferric chloride solution. To aqueous extract add gelatine and sodium chloride milky white color is produced. To the aqueous extract of amla add lead acetate , remove precipitate by filtration. To the filtrate add solution of 2:6 di- chlorophenol —indo-phenol , colour disappears . Uses – Dried fruit is useful in haemorrhage , diarrhoea , diabetes, and dysentery due to tannin. It has antioxidant, antibacterial and antiviral activities . Act as cardioprotective by regulating the blood pressure.
4. ARJUNA/ Terminalia arjuna Synonym – Arjunolic myrobalan Biological source – Bark of Terminalia arjuna Chemical constituent – The dry bark from the stem contains about 20 to 24% of tannin, whereas that of the bark obtained from the lower branches is up to 15 to 18%. The tannins present in arjuna bark are of mixed type consisting of both hydrolysable and condensed tannins.
The tannins are reported to be present are (+) catechol, (+) gallocatechol , epicatechol , epigallocatechol , and ellagic acid. The fruits also contain 7 to 20% of tannins Chemical Test Ethereal extract of arjuna shows pinkish fluoresces under ultra-violet light . Uses : Tannins are considered to have wound healing, astringent, hypotensive, antioxidant and antimicrobial effects. Also have property of anti dysenterics . The bark was extensively used in the past by the locals for tanning animal hides .
5. Mayaphal / Quercus infectoria Synonym – Nutgalls, blue galls Biological source – Gall of Quercus infectoria Chemical constituent – Nutgalls contains about 47.2 % tannin mainly gallotannic acid which is official tannic acid. Tannic acid of commerce is a hydrolysable tannin which yields gallic acid and glucose.
Uses - Because of its high tannin content , it have astringent properties, so it is employed for sore throat and receding gum. it is effective in treatment of piles. Tannic acid also used as an antidote for poisoning due to alkaloid, heavy metals and some glycosides. Its preparation can be used topically for the treatment of bedsores and minor ulcerations. Nutgall is the major source of tannic acid, which is largely used in tanning and dyeing industry and for the manufacture of ink. It is utilized in the lab. as a reagent for detection of gelatin and proteins.
B . CONDENSED TANNINS 1. Ashoka / Saraca indica Synonym – Sorrowless tree Biological source – D ried stem bark of the plant Saraca indica Chemical constituent – Ashoka stem bark contains about 6% of tannins . It is the type of Condensed tannin. Uses – It is suggested in all cases of uterine bleeding either abnormal uterine bleeding or excessive menstrual bleeding (Menorrhagia) . Chemical Tests - Powdered bark, when treated with saturated picric acid solution, remains brown for 10 minutes and then slowly turns to orange yellow. Powdered bark gives a deep chocolate color with 5% KOH solution .
2. Amra / Mangifera indica Synonym – M ango tree Biological source – Dried stem bark of the plant Mangifera indica Chemical constituent – Mango bark contain 10-20% tannin, namely Proto-catechuic acid and catechin . Uses Bark is used as astringent , antioxidant and also in treatment of diarrhea - dysentery . Tannins are associated to the astringent flavor of fruits and enzymatic browning reactions in mango bark
3. Pale catechin / Uncaria gambier Biological source – F rom the leaves and young twigs of Uncaria gambier Chemical constituent – Pale catechu contain from about 7 to 30% of pseudotannin catechin and 22 to 55% of a catechu-tannic acid. Both of the above component constitute over 60% of the drug. Uses Pale catechu is medicinally used as local astringent . In diarrhoea , it is used as general astringent . In case of oral gum bleeding, It is medicinally used for chewing with betel leaf. Large proportion of gambier is used in dyeing and tanning industries.
Chemical test - Test Procedure Observation Gambier fluorescein test To its alcohol extract, a little sodium hydroxide is added and shaken with petroleum ether. The petroleum ether layer shows green fluorescence . Black catechu gives negative Vanilin -hydrochloric acid test To its extract, a mixture of vanillin: alcohol: dilute HCl in the ratio 1:10:10 added. It gives pink or red colour . Matchstick dipped test A matchstick dipped in decoction of Pale catechu is air dried and again dipped into concentrated HCl and warmed near the burner. Pink or purple colour is produced.
4. Black catechu/ Acacia catechu Biological source – Black catechu is the dried aqueous extract prepared from the heartwood of Acacia catechu Chemical constituent- B lack catechu resembles pale catechu in its composition. It contains about 2–12% of catechin and about 25 to 33% of catechu-tannic acid.
Chemical test – Lime water when added to aqueous extract of black catechu gives brown colour , which turns to red precipitate on standing for some time. Green colour is produced when ferric ammonium sulphate is added to dilute solution of black catechu. By the addition of sodium hydroxide , the green colour turns to purple . Uses it is used in medicine as astringent. It cures troubles of mouth, diseases of the throat and diarrhoea . In India and eastern countries, it is used in betel leaves for chewing. In dyeing industries, it is used for dyeing fabrics brown or black. It is also used in calico printing.
5. Vijaysara / Pterocarpus marsupium Synonym – Indian kino tree, Malbar kino . Biological source – the stem bark of the plant Pterocarpus marsupium Chemical constituent – Kino contains about 70–80% of kino -tannic acid, kino -red, k-pyro- catechin (catechol), and gallic acid.
Chemical Tests When the solution of drug is treated with ferrous sulphate , green colour is produced. With alkali (like potassium hydroxide) violet colour is produced . Uses Kino is used as powerful astringent and also in the treatment of diarrhoea and dysentery, passive haemorrhage , toothache, and in diabetes . It is used in dyeing, tanning, and printing. The aqueous infusion of the wood is considered to be of much use in diabetes because it possess hypoglycaemic action due to presence of Epicatechin .
Side effects of tannin - Here, side effects refer only to relatively high doses of containing significant quantities of tannin. Or we can say, overcumptions lead to negative effect - N ausea – High intake of tannin lead – On empty stomach Due to excessive astringency , tannin bind to mucus membrane P roduce irritating effect Nausea
Reduce iron absorption – That’s why tannin should be avoid along with consumption of iron rich food or in patients with complaints iron deficiency. Interfere with macronutrients absorption – C hronic assumption of tannin particularly condensed tannin inhibit the action of certain digestive enzymes – CELLULASE , AMYLASE, LIPASE AND PROTECLYTIC enzymes on small intestinal mucosa which interferes with absorption of carb, protein and fat. Condensed tannins bind with the proteins in diet and interfere in nutrient digestion. Tannin posses much more affinity towards the protein than any other molecule.
Role in hepatotoxicity – Addition of tannic acid to barium sulphate mixture used in barium enemas increases the accuracy of examination and colonic mucosa s tand out clearly. But in 1964, this practices was banned by US FDA because several death caused by acute hepato -toxicity . Because – sufficient quantity of tannic acid absorb from colon reach to liver through blood steam and causes liver damage. Anti-nutrients – Tannin considered to be nutritionally undersirable . How ???? They form complex with protein, starch, and digestive enzyme to cause reduction in nutritional value of food by – Decrease in feed intake, growth rate, feed efficiency and protein digestibility.
Damage to mucosal lining of GI track Increased excretion of essential amino acids. Carcinogenic – Tannin has been listed as tentative carcinogen of Category I by OSHA. In research study, it is that the carcinogenic activity of tannin might be due to irritation and cellular damage instead of DNA Mutation. In a study, it is reported betel nuts containing 11 to 26% tannin are possibly responsible for development of oesophageal cancer. Tannic acid applied to burns or injected subcutaneously were reported to cause tumors in experimental animals.
Toxicity to ruminant – Hydrolysable tannin are toxic to ruminant. Here, microbial metabolism and gastric digestion convert HTs into absorbable low molecular weight metabolites. Some of these are toxic and mainly cause – Haemorrhagic gastroenteritis Necrosis of liver Kidney damage Condensed tannin damage the GI track, decreasing the absorption of nutrient and essential amino acid. Relation with migraine – Reduction in level of serotonin increases the severity of migraine due to unavailability of starch which is bounded by tannin and is precursor of serotonin.
List of some plants containing Tannins ( Acc to P.V.sharma vol.II )
List of some plants containing tannins - Sno . Plant Botanical name Plant part tannin in % Tannin role acc. To P.V. sharma (द्रव्य के कर्म) 1. Majuphal Quercus infectoria Gall 50 -70 % स्तम्भन 2. Babul Acacia arabica Bark 18- 27 % स्तम्भन 3. Amla Emblica officinalis Fruit 28-30% रसायन 4. Plaksh Ficus lacor Bark 4% मूत्रसंग्रहणीय 5. Avartani Helicteres isora Root, bark 10 -12 % स्तम्भन 6. Jambu Syzygium cumini Fruit 10-12% मूत्रसंग्रहणीय 7. Shigru Moringa oleifera Leaves ,drumstick 30 % त्वक विकारों में उपयुक्त 8. Patrang Caesalpinia sappan Pod 40 % आर्त्तवसंग्रहणीय 9. Mandukparni Centella asiatica All over in plant 20 -25% व्रणरोपक 10 Shal Shorea robusta Bark 10 -12 % मूत्रसंग्रहणीय
Sno . Plant Botanical name Plant part tannin in % Tannin role acc. To P.V. sharma (द्रव्य के कर्म) 11. Sarja Vateria indica Leaves , bark 30-40 % मूत्रसंग्रहणीय 12. Haritaki Terminalia chebula Fruit Around 30 % रसायन 13. Baheda Terminalia bellirica Fruit Around 20 % रक्तस्तम्भन 14. Bilva Aegle marmelos Pericarp 9 % ग्राही 15. Mahanimba Melia aredarach Bark 10-12% प्रमेहघ्न 16. Kampilak Mallotus philippensis Bark 6.5 % कुष् ठघ्न 17. Machika Tamarix articulate Tamarix gallica Gall Gall 48 % 40 % रक्तस्तम्भन , प्रदर और प्लीहावृद्धि में उपयुक्त 18. Karkatshringi Pistacia integerrima Gall 60 % दंतरोग, प्रदर, अतिसार में उपयोगी 19. Katphala Myristica esculenta Bark 32 % संधानीय 20. Pashanbhedh Saxifraga ligulata Root 15-16 % व्रणरोपक
Sno . Plant Botanical name Plant part tannin in % Tannin role acc. To P.V. sharma (द्रव्य के कर्म) 21. Dhataki Woodfordia fruticosa Flower 20- 24 % स्तम्भन , संधानीय योनिदोषहर 22. Chandan Santalum album Bark 12-14 % त्वक रोगों में उपयुक्त 23. Paan Piper betel Leaves 3- 4 % व्रणरोपक 24. Neem Azadirachta indica B ark 6 % व्रणरोकप, मधुमेहहर 25. Kanchnar Bauhinia variegata Leaves and bark 3-4 % रक्तस्तम्भन और आर्त्तवसंग्रहणीय 26. Vatas Salix caprea Bark 8-13 % रक्तस्तम्भन 27. Lajjalu Mimosa pudica Root 9-10 % संधानीय 28. Taruni Rosa centifolia Flower 2 % व्रणरोपक 29. Kadamba Anthocephalus indicus Bark 60-70 % योनिदोषहर 30. Ashoka Saraca asoca Bark 6 % आर्त्तवसंग्रहणीय
Conclusion In nutshell, it is concluded that a wide range of plant-based food products contain a significant amount of the tannins, which may possess both positive and negative effect (depending upon dose ). However, the negative effects of tannins can be dis-counted over the numerous health benefits it offers. T hus , tannins can be considered as a boon rather than a bane.