Tannins Flashcards
Comprised a large group of complex substances that are widely distributed in the plant kingdom
Tannins
When tannins occur in appreciable quantity, they are usually localized in specific part of plants such as
leaves, fruits, barks and stems
they are usually occur as mixtures of polyphenols that are difficult to separate because they do not crystallize
Tannins
Authors prefer this name than tannins
tannin extracts
Tannins are customarily divided into 2 classes based on the identity of the phenolic nuclei involved and on the way they are joined. These are __.
HYDROLYZABLE TANNINS
NON- HYDROLYZBLE TANNINS OR CONDENSED TANNINS
It consist of gallic acid or related polyhydric compounds esterified with glucose
HYDROLYZABLE TANNINS
Readily hydrolysable to yield the phenolic acids and the sugar
HYDROLYZABLE TANNINS
these tannins contain only phenolic nuclei but frequently are linked to carbohydrates or proteins
NON- HYDROLYZBLE TANNINS
non- crystallizable compounds that with water, form colloidal solutions possessing an acid reaction and a sharp “puckering” taste
Tannins
Tannins form what color with ferric salts
dark blue or greenish black soluble compounds
Tannins produce this color with potassium ferricyanide and ammonia
deep red color
In alkaline solutions, many of tannins derivatives readily absorb __
oxygen
When applied to living tissues, this action is known as an ___ and forms the basis for therapeutic application of tannins
astringent action
Because of their precipitating qualities, solutions of tannins are utilized in the laboratory as reagents for the detection of __,__,__.
gelatins, proteins, and alkaloids
HAMMAMELIS LEAF also known as
witch hazel leaves
HAMMAMELIS LEAF is the dried leaves of
Hammamelis virginia Linne
HAMMAMELIS LEAF consttituents
Hammamelitannin
Second tannin that appears to be derived from gallic acid
Hammamelitannin
Hammamelis leaf use
astringent and hemostatic properties
HAMMAMELIS WATER also known as
Distilled Witch Hazel Extract
Distilled Witch Hazel Extract Prepared by steam distillation of the recently cut and partially dried dormant twigs of
Hammamelis virginia
NUTGALL is the excrescence obtained from the young twigs of
Cuercus infectoria
the chief source of tannic acid is used in the tanning and in the dying industry
Nutgall
Japanese and Chinese galls are formed on __.
Rhus chinensis
True or false.
Tannic acid is not a single homogenous compound but is a mixture of esters of gallic acid with glucose whose exact composition varies according to its source
True
occurs as amorphous powder, glistening scales, or spongy masses that are light brown to yellowish white. The odor is faint and the taste is strongly astringent
Tannic acid
Tannic acid use
ASTRINGENT
