Tannins Overview

Compounds containing multiple phenol groups, responsible for astringent properties. They're found in plants and are often used in food, beverages, and medicine.

A test used to classify tannins. True tannins react positively, forming a precipitate with hide powder. Pseudotannins react weakly or not at all.

Large, complex molecules made of many smaller phenol units. These are responsible for the characteristic astringent properties often associated with tannins.

Tannins that do not react strongly in the Goldbeater's Skin Test. They are less effective at tanning.

These tannins can be broken down (hydrolyzed) by acids or enzymes. They are made up of smaller polyphenolic acids connected to a central sugar molecule.

These tannins cannot be broken down (hydrolyzed) by acids or enzymes. Instead, they are formed by the joining of smaller phenol units.

A type of hydrolysable tannin formed from gallic acid units. These are commonly found in plants like gallnuts, tea, and oak bark.

A type of hydrolysable tannin formed from hexahydrodiphenic acid units. They are often found in fruits like blueberries, raspberries, and strawberries.

Tannins that can be broken down into simpler molecules by hydrolysis, which release phenolic acids like pyrogallol upon dry distillation. They are soluble in water and form a blue color with ferric chloride.

Tannins that are not easily hydrolyzed into smaller components, also known as nonhydrolysable tannins. They are related to flavonoids in their structure and often linked to carbs or proteins. They produce red phlobaphens when treated with acids or enzymes.

A structural component of condensed tannins, a flavan-3-ol that contributes to their properties.

Another structural component of condensed tannins, a flavan-3,4-diol that often becomes part of the tannin structure.

Insoluble red products formed from condensed tannins when they are treated with acids or enzymes. They contribute to the red color of certain medicines like cinchona bark.

Simple phenolic compounds with lower molecular weights than regular tannins. They don't exhibit the same tanning properties as regular tannins.

A well-known pseudotannin found in many plants, a simple phenolic acid.

A specific type of pseudotannin that is common in plants, particularly in dead or dying cells.

A class of secondary metabolites that impact animal nutrition, known for their ability to bind with proteins and form complexes, and are commonly found in plants.

Tannins are soluble in water, alcohol, dilute alkali, and glycerin. They are sparingly soluble in ethyl acetate.

Tannins are insoluble in most organic solvents except acetone.

Tannins are oligomeric compounds, meaning they are made up of multiple smaller units linked together. These units are usually derived from phenolic compounds and have free phenolic groups.

Tannins can range in molecular weight from 500 to over 20,000. This wide range depends on the number of phenolic units linked together in the molecule.

Common tannins are often formed from gallic acid and ellagic acid. These acids undergo oxidative coupling to create larger tannin polymers.

A test that uses goldbeater's skin (a membrane from an ox's intestine) to detect the presence of tannins.

A test that uses phenazone solution to precipitate tannins from an aqueous solution.

A test that uses gelatin solution to precipitate tannins.

A test that uses a matchstick (containing lignin) to detect catechin, which reacts with hydrochloric acid to produce phloroglucinol, staining the wood pink or red.

A test that uses ammonia to detect chlorogenic acid, which turns green when exposed to air.

A test that uses vanillin and hydrochloric acid to produce phloroglucinol, which reacts with vanillin to give a pink or red color.

Complex molecules found in plants that have astringent properties.

Plants containing tannins as their major active constituents, such as oak bark, hamamelis leaves, and bearberry leaves.

Tannins are known to have an astringent pharmacological activity, which causes a tightening sensation.

The Gold Beater's Test is used to detect the presence of tannins by observing the formation of a precipitate with hide powder.

The enzyme tannase is responsible for breaking down tannins into smaller molecules.

A flavan-3-ol condensed tannin is also known as a catechin, a type of molecule found in plants.

Tannins are known for forming solutions with water and binding to proteins. However, they are non-crystalline substances and are not always soluble in acetone.

The plant Uncaria gambier is primarily grown for the pharmaceutically active drug it produces, which is mainly traded through Singapore.

The cultivation of Uncaria gambier involves sowing seeds in a nursery, allowing seedlings to grow for about nine months before transplanting them into open areas with spacing of approximately 3 meters.

The first harvest from Uncaria gambier is collected during the second year of growth, and involves gathering leaves and young shoots. Subsequent harvests occur annually.

While Uncaria gambier can produce leaves and twigs for up to 20 years, optimal yields are achieved during the eighth year of its growth cycle.

Cubes are produced by cooling and solidifying the concentrated extract, then cutting it into shape. The process involves boiling, draining, pressing, concentrating, and shaping in wooden trays.

Pale catechu, the extract of Uncaria gambier, contains two primary constituents: catechin, a pseudotannin, and catechutannic acid, a phlobatannin. These two make up over 60% of the extract.

Pale catechu also contains additional compounds such as catechu red, gambier fluorescin, and quercetin. Additionally, it has a small amount of indole alkaloids, including gambirtannin and its derivatives.

Gambirtannin, an indole alkaloid in pale catechu, displays a strong fluorescence under UV light.