Salivary Amylase Induction by Tannin-Enriched Diets as a Possible Countermeasure Against Tannins

Abstract

Tannins are characterized by protein-binding affinity. They have astringent/bitter properties that act as deterrents, affecting diet selection. Two groups of salivary proteins, proline-rich proteins and histatins, are effective precipitators of tannin, decreasing levels of available tannins. The possibility of other salivary proteins having a co-adjuvant role on host defense mechanisms against tannins is unknown. In this work, we characterized and compared the protein profile of mice whole saliva from animals fed on three experimental diets: tannin-free diet, diet with the incorporation of 5% hydrolyzable tannins (tannic acid), or diet with 5% condensed tannins (quebracho). Protein analysis was performed by one-dimensional gel electrophoresis combined with Matrix-Assisted Laser Desorption Ionization-Time of Flight mass spectrometry to allow the dynamic study of interactions between diet and saliva. Since abundant salivary proteins obscure the purification and identification of medium and low expressed salivary proteins, we used centrifugation to obtain saliva samples free from proteins that precipitate after tannin binding. Data from Peptide Mass Fingerprinting allowed us to identify ten different proteins, some of them showing more than one isoform. Tannin-enriched diets were observed to change the salivary protein profile. One isoform of α-amylase was overexpressed with both types of tannins. Aldehyde reductase was only identified in saliva of the quebracho group. Additionally, a hypertrophy of parotid salivary gland acini was observed by histology, along with a decrease in body mass in the first 4 days of the experimental period.

A 13-week subchronic toxicity study of grape skin extract in F344 rats

“…However, in the animals of the 5.0% groups, there were no significant changes of the parotid glands except for hypertrophy. Parotid gland hypertrophy similar to the one observed in the present study was reported in mice orally treated with 5.0% tannic acid, known as a bitter component, for ten days (da Costa et al, 2008). In the clinical observation, clear salivation could not be observed in the treated animals.…”

The Importance of Dietary Carbohydrate in Human Evolution

“…Tannins, and polyphenolic compounds more generally, can act as ubiquitous, nonspecific inhibitors of digestion enzymes and glucose transporters (Manzano and Williamson 2010;Mimsek et al 2014), thereby reducing the rate of digestion and absorption of key nutrients, particularly glucose (Zucker 1983). Tanninrich food has been shown to affect the activity of salivary amylase in some animals by increasing it in some cases (Ahmed et al 1991;Da Costa et al 2008;Lamy et al 2010), although the inverse has been observed in cockerels (Ahmed et al 1991).…”

Adaptive Parotid Gland Hypertrophy Induced by Dietary Treatment of GSE in Rats

“…For feeding experiments, GSE or tannic acid was mixed well with the powdered basal diet, CRF-1 (Oriental Yeast Co., Tokyo, Japan), at a concentration of 0% (control) or 5.0%. The dosage of GSE and tannic acid was determined based on results from the previous subchronic toxicity study and published report (da Costa et al 2008), respectively. For gavage experiments, the dose of GSE corresponded to 5.0% in the feeding experiment as calculated from the food consumption volume measured once a week in the feeding experiment.…”

“…Based on the fact that one a-amylase isoform was overexpressed in the saliva of mice treated with tannin-enriched diets which also induced parotid gland hypertrophy (Da costa et al 2008), indicated that GSE might induce the same a-amylase isoform as tannin-enriched diets only in the parotid gland, not in the other salivary glands. After the recovery period, a slight focal basophilic change in the parotid glands was observed in some of the animals in all of 6.-Ultrastructure of the glandular epithelial cells of parotid glands from rats treated with GSE or tannic acid by feeding for 4 weeks.…”