Gallic Acid Derivatives and Hydrolyzable Tannins

Haslam E (1989) Gallic acid derivatives and hydrolyzable tannins. In Rowe JW (ed) Natural products of woody plants chemicals extraneous to the lignocellulosic cell wall, vol 1. Springer, Berlin... 

Haslam, E. (1989). Gallic acid derivatives and hydrolyzable tannins. In Natural Products of Woody Plants Chemicals Extraneous to the Lignocellulosic Cell Wall, Vol. 1 (ed. J.W. Rowe), pp. 399-438. Springer-Verlag, Berlin. 

The in vivo assay for evaluation of antitumor activity of other tannins and related polyphenols was thus routinely performed by administration of tannins with a single intraperitoneal injection (10 mg/kg) to female ddY mice 4 days before inoculation of sarcoma 180 cells (1 x 10 ). Sixty days after inoculation of the tumor cells, survivors were killed and autopsied. The antitumor activity of each tannin was estimated by the number of regressors and the % increases in the life span (% ILS) [107]. Among approximately 100 polyphenols of different types tested, most of the oligomeric hydrolyzable tannins exhibited a potent activity in contrast to the negligible activity of the monomeric hydrolyzable tannins, proanthocyanidins and their related low-molecular weight polyphenols such as gallic acid, catechins and caffeoyl derivatives. 

Gallic acid (3,4,5-trihydroxybenzoic acid) can be formed by acid hydrolysis of hydrolyzable tannins. Differences among the ester derivatives are only in the number of carbon atoms in the aliphatic side-chain. These differences confer different physicochemical characteristics, especially in lipophilicity evaluated by the value of partition coefficient (C log P). Chemical modifications in the gallic acid molecule can alter the pharmacokinetic and pharmacodynamic properties, such as changing the solubility and the degree of ionization. The names of the compounds are abbreviated according to the length of the side-chain (Locatelli et al., 2013). 

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