Tannins

Tannins
Tannins are complex substances that usually occur as mixtures of polyphenols that are very difficult to separate since they do not crystallize.

OR
Tannins are polyhydroxy
phenolic compounds.


Tannins are found commonly
in the bark of trees, wood,
leaves, buds, stems, fruits,
seeds, roots and plant galls.

Tannins are complex chemical substances derived from phenolic acids (sometimes called tannic acid). They are classified as phenolic compounds, which are found in many species of plants.
Tannins are high molecular weight phenolic compounds commonly found in plants with molecular weights ranging from 500 to over 3000 Dalton and up to 20,000 Dalton.
Examples of plant species used to obtain tannins for tanning purposes are wattle (Acacia sp.), oak (Quercus sp.), eucalyptus (Eucalyptus sp.), birch (Betula sp.), willow (Salix caprea), pine (Pinus sp.), quebracho (Scinopsis balansae) .

1. "T annins" P resented to : d r Muhammad Qasim Hayat P resented by : F ilza M ustafa 1

2. Tannins Tannins are complex substances that usually occur as mixtures of polyphenols that are very difficult to separate since they do not crystallize . OR Tannins are polyhydroxy phenolic compounds. Tannins are found commonly in the bark of trees, wood, leaves, buds, stems, fruits, seeds, roots and plant galls. 2

3. Tannins Tannins are complex chemical substances derived from phenolic acids (sometimes called tannic acid). They are classified as phenolic compounds, which are found in many species of plants. Tannins are high molecular weight phenolic compounds commonly found in plants with molecular weights ranging from 500 to over 3000 Dalton and up to 20,000 Dalton. Examples of plant species used to obtain tannins for tanning purposes are wattle (Acacia sp.), oak (Quercus sp.), eucalyptus (Eucalyptus sp.), birch (Betula sp.), willow (Salix caprea), pine (Pinus sp.), quebracho (Scinopsis balansae) . 3

4. Classification of tannins 4

5. Pseudo tannins True tannins Phenolic compounds of plant origin that don't convert animal hide to leather but do give positive Gold beater’s skin test, are called pseudo tannins. Polyhydroxy phenolic compounds which convert animal hide to leather by precipitating proteins and give positive Gold beater’s skin test, are called true tannins. Molecular weight is less than true tannins. Molecular weight is 1000-5000 5

6. 2 nd classification 6

7. Sources of tannins 7

8. Physical Properties Color: Dark brown or reddish brown Taste: Puckering taste State: Non-crystalline Solubility: Soluble in water, alcohol, dilute alkalis, glycerols and acetone. 8

9. Chemical properties Precipitation Anti-oxidizing properties Astringent Reaction with salts Reaction with potassium ferricyanide and ammonia 9

10. 10 Flow chart of Tannin extraction and processing

11. Extraction methods for Tannins Maceration Decoction Pressurized water extraction Ultrasound method Microwave assisted extraction Infrared assisted extraction Soxhlet extraction Super critical extraction Enzyme assisted extraction 11

12. Identification t ests for Tannins Color reactions Alkaloid precipitation Gelatin test Goldbeater’s skin test Ferric chloride test Matchstick test Chlorogenic acid test 12

13. Matchstick test Dip matchstick in plant extract. Dry it. Moisten it with hydrochloric acid. And warm near flame. Wood will turn pink or red in color due to phloroglucinol. 13

14. Gold beater’s skin test Soak a small piece of Gold beater’s skin in 2% hydrochloric acid. Rinse it with distilled water. Place it in solution to be tested for 5 minutes. Wash in water and transfer to 1% solution of ferrous sulphate. Black or brown color of skin indicates presence of tannins. It is a quantitative test and +ve only for true tannins. 14

15. Phenazone test Take 5ml of aqueous extract of drug. Add 0.5grams of sodium acid phosphate. Warm it and cool. Filter solution. To the filtrate, add 2%solution of Phenazone. Tannins will be precipitated. Precipitates will be bulky and colored. 15

16. Test with Gelatin solution Take 1 ml of the extract in a test tube and added 1ml of gelatin (1%solution) and NaCl. The formation of a white precipitate will show The presence of tannins. 16

17. 17 Biological activities of Tannins Anti -inflammatory Anti-oxidant Biological activities of Tannins Anti -hyperglycemic Anti -apoptotic Anti-aging Anti-bacterial

18. Medicinal plant Plant part Activity of Tannins Mimosa arenosa Stem bark Antibacterial activity against Gram +ve and Gram-ve bacteria Mimosa tenuiflora Stem bark Wound healing, gastric ulcer, inflammation and burns etc Piptadenia stipulacea Stem Antimicrobial activity Anacardium occidentale Leaves Antimicrobial and non stick activity Anadenanthera colubrina Leaves, seeds and stem bark Anti-inflammatory, antioxidant, astringent activity Solanum paniculatum Roots and stem Treat chronic hepatitis and chronic arthritis etc Uncaria gambir Leaves Astringent Quercus infectoria Galls obtained from twigs Antidote for alkaloidal poisoning 18

19. Uses of Tannins Currently, tannins have been applied into many different fields including medicine, food, beverage, manufacture of ink and adhesives, dye and tanning industry, plastic resins, water purification, and surface coatings . The tannin-containing plant extracts are used as astringents, against diarrhea, as diuretics, against stomach and duodenal tumors, as anti-inflammatory, antiseptic, antioxidant and haemostatic pharmaceuticals etc. 19

20. Medicinal and biological properties of Tannins Medical research has shown that tannin found in cranberries is highly effective in preventing urinary tract infections by preventing E. coli bacteria from adhering to walls of the urinary tract. 20

21. Medicinal and biological properties Tannin-containing drugs precipitate proteins and have been traditionally used as styptics (stop hemorrhage) and internally for the protection of inflamed surfaces of mouth and throat. They play an important role in the treatment of burns. They form a mild antiseptic protective layer on the surface of the injured skin below which regeneration of new tissue takes place. They act as anti-diarrhea although not recommended in this respect as they usually delay elimination of bacterial toxins from the body. 21

22. Medicinal and biological properties Tannins have been employed as antidote in poisoning by heavy metals, alkaloids and certain glycosides due to their precipitation as tenants. Recently tannins as most polyphenols were proved to have a potent antioxidant effect. Studies on the antitumor effect of tannins proved that a strong activity is obtained with ellagitannins having galloyl groups at the O-2 and O-3 positions of the glucose core, as in the tellimagrandins. Certain tannins were proved to have anti-HIV activities. 22

23. Anti diabetic 23

24. Treatment of Alzheimer and Parkinson diseases 24

25. Tannic acid30 Mostly used locally against excessive secretion of mucous membranes, to contract tissue and check hemorrhage . Use in constipation, to treat pain in abdomen, sensitive to pressure. 25

26. Taninal Taninal Taninal is traditionally applied in diarrheas and in case of food poisoning. 26

27. 27 Thank You!