Astringency of aqueous solutions of phenolic compounds (grape seed tannins, tannic acid, catechin and gallic acid) increased upon addition of citric acid, whereas the astringency of alum was reduced. Astringency of alum was decreased equivalently by addition of equi-sour levels of lactic acid, citric acid or hydrochloric acid. The difference between alum and the phenolic compounds is speculated...

A new, facile, cost effective, and eco-friendly protocol is reported for the synthesis of 2,3-dihydroquinazoline-4-(1H)-ones exploring tannic acid as a novel, inexpensive, andbiodegradable catalyst. A variety of dihydroquinazolins were prepared from aromatic aldehydesand anthranilamide using catalytic amount of tannic acid under solvent free conditions.Operational simplicity, high yield, and hi...

Astringent compounds were applied to oral epithelium of the clawed toad, Xenopus laevis, and rapidly rising and highly sensitive responses could be recorded from the whole glossopharyngeal nerve, but not at all from the trigeminal nerve. The response to 10 mM tannic acid decreased progressively with repetitive application. These responses to tannic acid, however, recovered completely by treatin...

A spectrophotometric method is proposed for the determination of the polyphenols content in aqueous extracts of plants. The method is based on the reduction of Cu(II) to Cu(I) by polyphenols, in the presence of bicinchoninic acid in a buffered medium (ammonium acetate, pH 7.0) with the formation of Cu(I)/BCA complexes. A calibration curve of absorbance (at 558 nm) vs tannic acid concentration i...

By C. J. Warden, officiating Civil-Surgeon, Bhaugulpore. The chemical changes which drugs undergo before absorption into the blood, is a subject of great interest; and valuable hints for the treatment of disease, have been obtained by observing the form in which substances appear after having passed through the circulatory system. For instance, it is well known that tannic acid is a more powerf...

The purpose of this study was to determine whether tannic acid elicits neurogenic plasma exudation from the oral mucosa in vivo and, if so, whether this response is transduced in part by thel-arginine-nitric oxide (NO) biosynthetic pathway. Using intravital microscopy, we found that suffusion of tannic acid elicits significant concentration-dependent leaky site formation and increase in clearan...

The purpose of this study was to quantify the degree of suppression of the perceived bitterness of quinine by various substances and to examine the mechanism of bitterness suppression. The following compounds were tested for their ability to suppress bitterness: sucrose, a natural sweetener; aspartame, a noncaloric sweetener; sodium chloride (NaCl) as the electrolyte; phosphatidic acid, a comme...