[M2] Pharmacognosy - Tannins

Tannins

Complex polyphenols that are difficult to separate because they do not crystallize

Sharp puckering taste

Tannins are characterized by a ____.

Proteins, Alkaloids, and Glycosides

Tannins cause the precipitation of ________

Astringent, Diuretic

Aside from its application in leather-making, tannins are classified as _______ and _______.

Hydrolyzable, Non-Hydrolyzable Tannins

True Tannins, classification

Quinic Acid, Chlorogenic Acid

Pseudotannins - too small, examples:

Glucose + Phenolic Acid

Main Component of Hydrolyzable Tannins

Flavonoids

Main Component of Nonhydrolyzable Tannins

Gallic Acid, Ellagic Acid

Examples of Glucose + Phenolic Acid (hydrolyzable tannins)

Cyanidin

Example of Flavonoids in the N-Hydrolyzable Tannins

Pyrogallol

Upon dry distillation, hydrolyzable tannins yield _______

Pyrocatechol

Upon dry distillation, nonhydrolyzable tannins yield _______

Phenolic Acid, Sugar

Upon hydrolysis, hydrolyzable tannins yield _______

Phlobaphenes

Upon hydrolysis, nonhydrolyzable tannins yield _______

Bloom Leather

Leather ppt of Hydrolyzable Tannins

Tanner's Red

Leather ppt of Nonhydrolyzable Tannins

(-) retain Br color, Colorless, Blue Black

Results of Hydrolyzable Tannins after undergoing different tests:

1) Bromine Test

2) KMnO4

3) FeCl3

(+) colorless, Violet, Green-Black

Results of Nonhydrolyzable Tannins after undergoing different tests:

1) Bromine Test

2) KMnO4

3) FeCl3

Gelatin Test

General Test for Tannins

Goldbeater's Skin Test

Test for differentiation of Tannins based on leather precipitation

True Tannins

Test (+) in the Goldbeater's Skin Test and can either precipitate Bloom's Leather or Tanner's Red

Pseudotannins

Test (-) in the Goldbeater's Skin Test as they are too small and contain very low molecular weight

Nutgall

A/C: Tannic Acid (Gallic, Ellagic); excrescence from twigs of Nutgall Tree when an insect deposits its ova

Universal Antidote

Tannic Acid is a component of the (), but is also used in the tanning or dyeing industry

Quercus infectoria

Nutgall, the most important source of tannins

Cynips tinctoria

Insect that deposits its ova in the Nutgall Tree

Hammamelis virginiana

Witch Hazel/Hammamelis

Hammamelitannin

A/C of Witch Hazel, which is used as () in cosmetic preparations