Tannins resistance

Bhatta R, Krishnamoorthy U, Mohammed F (2001) Effect of tamarind Tamarindus indica) seed husktarmins on in vitro rumen fermentation. Anim Feed Sci Technol 90 143-152 Brooker JD, O Donovan LA, Skene I, Clarke K, BlackaU L, Muslera P (1994) Streptococcus caprinus sp. nov., a tannin-resistant mminal bacterium from feral goats. Lett Appl Microbiol 18 313-318... 

Tannins are polyhydroxyphenols. They are soluble in water, aleohols and aeetone and ean eoagulate proteins. They are yielded by extraetion from wood substanee, bark, leaves and fruits. Other components of the extraction solutions are sugars, pectins and other polymeric carbohydrates, amino acids and other substances. The content of non-tannins can reduce wood failure and water resistance of glued bonds. The polymeric carbohydrates especially increase the viscosity of the extracts. 

The resistance of BW tannins (sodium tannates) to thermal breakdown is aided by the presence of sufficient alkali, and optimum stability is conferred at an alkalinity tannin ratio of 2 1. 

The classic seed burial studies of W. J. Beal and his successors have shown seeds of at least one weed species, Moth Mullein (Verbascum blattaria L.) can remain viable in soil for a peiod of 100 years, whereas three species continued to germinate after 80 years of burial (30). Weed seeds not only resist decay by soil microbes, but they vary in dormancy characteristics. There is considerable evidence that chemical inhibitors are responsible for both phenomena. Unsaturated lactones and phenolic compounds in particular, are potent antimicrobial compounds present in many seeds (4J. Fruits and seeds are also known to contain diverse germination inhibitors including phenolic compounds, flavonoids and/or their glycosides and tannins. Unique methods to destroy inhibitors could provide an excellent weed management strategy. 

All the tannins readily react with proteins, forming insoluble, stable compounds when they react with collagen, the main constituent of animal skin, they form leather, a material that is resistant to hydrolysis, oxidation, and biological attack and therefore stable to weathering and resistant to decomposition. Since tannins from different plant sources have different chemical compositions, each tannin used for tanning skin produces a leather having slightly different properties and color. Tannins that have... 

Chemical defenses Physical defenses Resistance Phloro tannins... 

Thiolysis also proved useful for the analysis of derived tannins. Methylmethine-linked tannin-like compounds resulting from acetaldehyde-mediated condensation of flavanols (see Section 5.5.S.2) yielded several adducts when submitted to acid-catalyzed cleavage in the presence of ethanethiol, providing information on the position of linkages in the original ethyl-linked compounds. " Thiolysis of red wine extracts released benzylthioether derivatives of several anthocyanin-flavanol adducts, indicating that such structures were initially linked to proanthocyanidins. However, some of the flavonoid derivatives present in wine (e.g., flavanol-anthocyanins ) are resistant to thiolysis, while others (e.g., flavanol-ethyl anthocyanins) were only partly cleaved. Thiolysis, thus, appears as a rather simple, sensitive, and powerful tool for quantification and characterization of proanthocyanidins, but provides mostly qualitative data for their reaction products. 

Grayer, R.J. et al.. Condensed tannin levels and resistance of groundnuts against Aphis craccivora. Phytochemistry, 31, 3795, 1992. 

Hence tannin-tolerant insects with elevated gut pH s may be relatively resistant to these pathogens. According to theory (69,70), early successional plants should have low tannin contents and their herbivores should have lower gut pH values... 

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