Page 97 - Pharmd general phytochemistry I-Final2024_LEUCTERS

Tannins

 High molecular weight phenolic plant constituents that can be detected

by the Goldbeater’s Skin tanning test.

 This exclude simple low molecular weight compounds such as gallic acid,

catechin and chlorogenic acid (Pseudotannins)

 Detected qualitatively by Goldbeater’s Skin test and quantitatively by

absorption on standard hide powder.

 Tannins constitute a large group of widely distributed phenolic plant

constituents, and characterized by being able to combine with proteins of
animal hides thus preventing their putrefaction and converting them into
leather.
However, it is only high molecular weight tannins that are capable of
tanning hide, so it is more acceptable to define tannins as those high
molecular weight phenolic plant constituents that can be detected by the
Goldbeater's Skin tanning test. This will exclude simple low molecular
weight compounds such as gallic acid, catechin and chlorogenic acid, that
usually coexist with tannins.
These simpler, tannin-like compounds (gallic, catechin flavan-3,4-diol and
chlorogenic acid) are referred to as, Pseudotannins.

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