Uptake of Terminalia chebula tannin components by hide: analysis using tlc-uv densitometry

A method of separation and quantitative analysis of Terrninnlia cllebula tannins by tlc-uv densitometry is described. The method is applicable over a range of 0.5 to 2.5 pg/tlc spot and has coefficient of variation of 4-6% for the individual tannins. Using the method on individual tannin components, mixtures of components and myrobalan extracts it has been found that at a level of 0.5% concentration, chebulinic acid and chebulagic acid are taken up rapidly by hide, their rate of uptake being faster than the products of decomposition (by heat in aqueous solution) of chebulinic acid. The latter indicates an advantage in extracting myrobalan tannins under mild conditions. The study also showed that the optimum pH for uptake of chebulinic acid by hide is 4.1 indicating that the ionization of the carboxylic acid group may play a role in tanning by this compound.