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Special Issue "Tannins"

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A special issue of Molecules (ISSN 1420-3049).

Deadline for manuscript submissions: closed (20 January 2011)

Special Issue Editor

Guest Editor
Dr. Amy B. Howell

Marucci Center for Blueberry Cranberry Research, Rutgers University, 125A Lake Oswego Rd., Chatsworth, NJ 08019, USA
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Special Issue Information

Dear Colleagues,

Tannins are a widely distributed group of compounds, found throughout the plant kingdom. There are two distinct types of tannins, the hydrolyzable tannins, which are polymers of ellagic or gallic acid esterified to a carbohydrate (usually glucose), and condensed tannins (proanthocyanidins), which are polymers of flavan-3-ols. Tannins can be high molecular weight, have very heterogeneous structures, and can form complexes with a number of other molecules (especially proteins and carbohydrates). All of these characteristics of tannins can influence their biological properties.

Tannins are astringent defense compounds that serve as predator feeding deterrents, and are produced by plants in times of stress, acting as antimicrobials. They may also play a role in fruit ripening and plant growth regulation. Tannins have a number of industrial uses, including dying and preserving, converting animal hides to leather, and the precipitation of proteins in wine and beer.

Historically, ingestion of tannins has been associated with anti-nutritional effects, especially on protein digestibility in ruminant animals. However, recent research on tannins has focused on their potential to positively impact human health, when consumed in the proper dosage and structural form. Tannins have demonstrated a host of potent biological activities, including bacterial anti-adhesion activity, anti-parasitic, antioxidant, anti-inflammatory and anti-proliferative activities, as well as influencing cell signaling and gut health.

This special issue of Molecules will consider submissions related to all characteristics of tannins (both hydrolyzable and condensed), including biological and chemical properties and potential human health effects.

Dr. Amy B. Howell
Guest Editor

Keywords

  • tannin
  • proanthocyanidin
  • condensed tannin
  • hydrolyzable tannin
  • ellagitannin
  • gallotannin
  • flavan-3-ol
  • polyphenol
  • chemical properties
  • astringency
  • protein precipitation
  • biological activities
  • health effects

Published Papers (9 papers)

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Research

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Open AccessArticle A-Type Cranberry Proanthocyanidins Inhibit the RANKL-Dependent Differentiation and Function of Human Osteoclasts
Molecules 2011, 16(3), 2365-2374; doi:10.3390/molecules16032365
Received: 7 February 2011 / Revised: 7 March 2011 / Accepted: 9 March 2011 / Published: 11 March 2011
Cited by 11 | PDF Full-text (1104 KB)
Abstract
This study investigated the effect of A-type cranberry proanthocyanidins (AC-PACs) on osteoclast formation and bone resorption activity. The differentiation of human pre-osteoclastic cells was assessed by tartrate-resistant acid phosphatase (TRAP) staining, while the secretion of interleukin-8 (IL-8) and matrix metalloproteinases (MMPs) was measured
[...] Read more.
This study investigated the effect of A-type cranberry proanthocyanidins (AC-PACs) on osteoclast formation and bone resorption activity. The differentiation of human pre-osteoclastic cells was assessed by tartrate-resistant acid phosphatase (TRAP) staining, while the secretion of interleukin-8 (IL-8) and matrix metalloproteinases (MMPs) was measured by ELISA. Bone resorption activity was investigated by using a human bone plate coupled with an immunoassay that detected the release of collagen helical peptides. AC-PACs up to 100 µg/mL were atoxic for osteoclastic cells. TRAP staining evidenced a dose-dependent inhibition of osteoclastogenesis. More specifically, AC-PACs at 50 µg/mL caused a 95% inhibition of RANKL-dependent osteoclast differentiation. This concentration of AC-PACs also significantly increased the secretion of IL-8 (6-fold) and inhibited the secretion of both MMP-2 and MMP-9. Lastly, AC-PACs (10, 25, 50 and 100 µg/ml) affected bone degradation mediated by mature osteoclasts by significantly decreasing the release of collagen helical peptides. This study suggests that AC-PACs can interfere with osteoclastic cell maturation and physiology as well as prevent bone resorption. These compounds may be considered as therapeutic agents for the prevention and treatment of periodontitis. Full article
(This article belongs to the Special Issue Tannins)
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Open AccessArticle Cranberry Proanthocyanidins Mediate Growth Arrest of Lung Cancer Cells through Modulation of Gene Expression and Rapid Induction of Apoptosis
Molecules 2011, 16(3), 2375-2390; doi:10.3390/molecules16032375
Received: 28 January 2011 / Revised: 8 March 2011 / Accepted: 10 March 2011 / Published: 11 March 2011
Cited by 23 | PDF Full-text (442 KB)
Abstract
Cranberries are rich in bioactive constituents purported to enhance immune function, improve urinary tract health, reduce cardiovascular disease and more recently, inhibit cancer in preclinical models. However, identification of the cranberry constituents with the strongest cancer inhibitory potential and the mechanism associated with
[...] Read more.
Cranberries are rich in bioactive constituents purported to enhance immune function, improve urinary tract health, reduce cardiovascular disease and more recently, inhibit cancer in preclinical models. However, identification of the cranberry constituents with the strongest cancer inhibitory potential and the mechanism associated with cancer inhibition by cranberries remains to be elucidated. This study investigated the ability of a proanthocyanidin rich cranberry fraction (PAC) to alter gene expression, induce apoptosis and impact the cell cycle machinery of human NCI-H460 lung cancer cells. Lung cancer is the leading cause of cancer-related deaths in the United States and five year survival rates remain poor at 16%. Thus, assessing potential inhibitors of lung cancer-linked signaling pathways is an active area of investigation. Full article
(This article belongs to the Special Issue Tannins)
Open AccessArticle Tannin Composition of Cabernet-Sauvignon and Merlot Grapes from the Bordeaux Area for Different Vintages (2006 to 2009) and Comparison to Tannin Profile of Five 2009 Vintage Mediterranean Grapes Varieties
Molecules 2011, 16(2), 1519-1532; doi:10.3390/molecules16021519
Received: 25 January 2011 / Accepted: 9 February 2011 / Published: 11 February 2011
Cited by 13 | PDF Full-text (292 KB)
Abstract
The proanthocyandin composition of skins and seeds of Bordeaux Merlot (M) and Cabernet Sauvignon (CS) grapes was evaluated by HPLC-UV-fluorescence for four consecutive vintages (2006 to 2009). The results indicated a strong vintage effect on the tannin profile of each variety. However, and
[...] Read more.
The proanthocyandin composition of skins and seeds of Bordeaux Merlot (M) and Cabernet Sauvignon (CS) grapes was evaluated by HPLC-UV-fluorescence for four consecutive vintages (2006 to 2009). The results indicated a strong vintage effect on the tannin profile of each variety. However, and in spite of the vintage effect, some tannin characteristics such as mDP, %G and %P allow discrimination of both Bordeaux varieties. The same analyses were carried out for the 2009 vintage of five Mediterranean grape varieties (Syrah, Grenache, Mourvedre, Carignan and Counoise). The results demonstrated differences among these five varieties. Syrah appeared to exhibit the highest concentrations of flavanol monomers and dimmers, especially in skins. The comparison study between Bordeaux and Mediterranean grape varieties for the same vintage (2009) revealed that mDP and %G for seed extracts were parameters specific to each vineyard area. Full article
(This article belongs to the Special Issue Tannins)
Open AccessArticle Tannin Fingerprinting in Vegetable Tanned Leather by Solid State NMR Spectroscopy and Comparison with Leathers Tanned by Other Processes
Molecules 2011, 16(2), 1240-1252; doi:10.3390/molecules16021240
Received: 6 December 2010 / Revised: 26 January 2011 / Accepted: 27 January 2011 / Published: 28 January 2011
Cited by 7 | PDF Full-text (409 KB)
Abstract
Solid state 13C-NMR spectra of pure tannin powders from four different sources – mimosa, quebracho, chestnut and tara – are readily distinguishable from each other, both in pure commercial powder form, and in leather which they have been used to tan.  Groups
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Solid state 13C-NMR spectra of pure tannin powders from four different sources – mimosa, quebracho, chestnut and tara – are readily distinguishable from each other, both in pure commercial powder form, and in leather which they have been used to tan.  Groups of signals indicative of the source, and type (condensed vs. hydrolyzable) of tannin used in the manufacture are well resolved in the spectra of the finished leathers.  These fingerprints are compared with those arising from leathers tanned with other common tanning agents.  Paramagnetic chromium (III) tanning causes widespread but selective disappearance of signals from the spectrum of leather collagen, including resonances from acidic aspartyl and glutamyl residues, likely bound to Cr (III) structures. Aluminium (III) and glutaraldehyde tanning both cause considerable leather collagen signal sharpening suggesting some increase in molecular structural ordering. The 27Al-NMR signal from the former material is consistent with an octahedral coordination by oxygen ligands. Solid state NMR thus provides easily recognisable reagent specific spectral fingerprints of the products of vegetable and some other common tanning processes. Because spectra are related to molecular properties, NMR is potentially a powerful tool in leather process enhancement and quality or provenance assurance. Full article
(This article belongs to the Special Issue Tannins)
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Open AccessArticle Antioxidant Tannins from Stem Bark and Fine Root of Casuarina equisetifolia
Molecules 2010, 15(8), 5658-5670; doi:10.3390/molecules15085658
Received: 21 July 2010 / Revised: 10 August 2010 / Accepted: 13 August 2010 / Published: 16 August 2010
Cited by 8 | PDF Full-text (360 KB)
Abstract
Structures of condensed tannins from the stem bark and fine root of Casuarina equisetifolia were identified using MALDI-TOF MS and HPLC analyses. The condensed tannins from stem bark and fine root consist predominantly of procyanidin combined with prodelphinidin and propelargonidin, and epicatechin is
[...] Read more.
Structures of condensed tannins from the stem bark and fine root of Casuarina equisetifolia were identified using MALDI-TOF MS and HPLC analyses. The condensed tannins from stem bark and fine root consist predominantly of procyanidin combined with prodelphinidin and propelargonidin, and epicatechin is the main extension unit. The condensed tannins had different polymer chain lengths, varying from trimers to tridecamer for stem bark and to pentadecamer for fine root. The antioxidant activities were measured by two models: 1,1-diphenyl-2- picrylhydrazyl (DPPH) radical scavenging activity and ferric reducing/ antioxidant power  (FRAP). The condensed tannins extracted from C. equisetifolia showed very good DPPH radical scavenging activity and ferric reducing/ antioxidant power, suggesting that these extracts may be considered as new sources of natural antioxidants for food and nutraceutical products. Full article
(This article belongs to the Special Issue Tannins)

Review

Jump to: Research

Open AccessReview The Effect of Tannins on Mediterranean Ruminant Ingestive Behavior: The Role of the Oral Cavity
Molecules 2011, 16(4), 2766-2784; doi:10.3390/molecules16042766
Received: 21 January 2011 / Revised: 10 March 2011 / Accepted: 22 March 2011 / Published: 25 March 2011
Cited by 12 | PDF Full-text (208 KB)
Abstract
Sheep, cattle and goat are domestic ruminants of significant economic interest in the Mediterranean region. Although sharing the same pasture ranges, they ingest different plants and plant parts and, consequently different levels of tannins. This suggests an ability to detect and adapt ingestion
[...] Read more.
Sheep, cattle and goat are domestic ruminants of significant economic interest in the Mediterranean region. Although sharing the same pasture ranges, they ingest different plants and plant parts and, consequently different levels of tannins. This suggests an ability to detect and adapt ingestion according to animal physiological limits of tolerance for plant secondary metabolites. This review will detail the effects of dietary tannins on feeding behavior, and the role of the oral cavity in this process, with focus on such ruminant species. The role of salivary protein profile in tannin perception in the oral cavity, and as a defense mechanism, will be discussed. Full article
(This article belongs to the Special Issue Tannins)
Open AccessReview Wine and Grape Tannin Interactions with Salivary Proteins and Their Impact on Astringency: A Review of Current Research
Molecules 2011, 16(3), 2348-2364; doi:10.3390/molecules16032348
Received: 9 February 2011 / Revised: 2 March 2011 / Accepted: 9 March 2011 / Published: 11 March 2011
Cited by 57 | PDF Full-text (225 KB)
Abstract
Astringency is an important characteristic of red wine quality. The sensation is generally thought to be produced by the interaction of wine tannins with salivary proteins and the subsequent aggregation and precipitation of protein-tannin complexes. The importance of wine astringency for marketability has
[...] Read more.
Astringency is an important characteristic of red wine quality. The sensation is generally thought to be produced by the interaction of wine tannins with salivary proteins and the subsequent aggregation and precipitation of protein-tannin complexes. The importance of wine astringency for marketability has led to a wealth of research on the causes of astringency and how tannins impact the quality of the sensation, particularly with respect to tannin structure. Ultimately, the understanding of how tannin structure impacts astringency will allow the controlled manipulation of tannins via such methods as micro-oxygenation or fining to improve the quality of wines. Full article
(This article belongs to the Special Issue Tannins)
Open AccessReview Tannins of Constant Structure in Medicinal and Food Plants—Hydrolyzable Tannins and Polyphenols Related to Tannins
Molecules 2011, 16(3), 2191-2217; doi:10.3390/molecules16032191
Received: 19 January 2011 / Revised: 24 February 2011 / Accepted: 28 February 2011 / Published: 4 March 2011
Cited by 44 | PDF Full-text (583 KB)
Abstract
In addition to the commonly used classification as hydrolyzable tannins and condensed tannins, tannins can also be categorized into two other types: polyphenols of constant chemical structure (Type A) and polyphenols of variable composition (Type B). Both types of tannins and related polyphenols
[...] Read more.
In addition to the commonly used classification as hydrolyzable tannins and condensed tannins, tannins can also be categorized into two other types: polyphenols of constant chemical structure (Type A) and polyphenols of variable composition (Type B). Both types of tannins and related polyphenols account for a large part of plant polyphenols, but accurate structure-activity correlations on a molecular basis can be determined mainly for type A compounds, among which are hydrolysable tannins such as the ellagitannins and their oxidized congeners, some gallotannins, epigallocatechin gallate, caffetannins, etc. Among the activities determined on a molecular basis are the chemical, biological and pharmacological actions such as superoxide anion scavenging, apoptosis, antitumor, anti-EVB, anti-MRSA and anti-plasmin inhibitory activities, etc., in addition to their fundamental activities, i.e., binding to proteins, large molecular compounds and metallic ions, and antioxidant activities. Some structure-specific activities were found for the condensation of dehydroellagitannins with co-existing compounds under mild conditions, and the host-mediated antitumor actions of ellagitannin oligomers. Structures and activities of metabolites of geraniin, a dehydroellagitannin, were revealed. Some stilbenoids and phlorotannins of firm structures have been known to have many activities similar to those of the type A tannins. Full article
(This article belongs to the Special Issue Tannins)
Open AccessReview The Ups and Downs of Tannins as Inhibitors of Poly(ADP-Ribose)glycohydrolase
Molecules 2011, 16(2), 1854-1877; doi:10.3390/molecules16021854
Received: 24 January 2011 / Accepted: 17 February 2011 / Published: 22 February 2011
Cited by 20 | PDF Full-text (1312 KB)
Abstract
DNA damage to cells activates nuclear poly(ADP-ribose)polymerases (PARPs) and the poly(ADP-ribose) (PAR) synthesized is rapidly cleaved into ADP-ribose (ADPR) by PAR glycohydrolase (PARG) action. Naturally appearing tannin-like molecules have been implicated in specific inhibition of the PARG enzyme. This review deals with the
[...] Read more.
DNA damage to cells activates nuclear poly(ADP-ribose)polymerases (PARPs) and the poly(ADP-ribose) (PAR) synthesized is rapidly cleaved into ADP-ribose (ADPR) by PAR glycohydrolase (PARG) action. Naturally appearing tannin-like molecules have been implicated in specific inhibition of the PARG enzyme. This review deals with the in vitro and in vivo effects of tannins on PAR metabolism and their downstream actions in DNA damage signaling. Full article
(This article belongs to the Special Issue Tannins)

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