Structural determinants of the platelet agonist activity of cotton bract condensed tannin

Rohrbach, Michael S.; Kreofsky, Teresa J.; Chan, Bock G.

doi:10.1016/s0013-9351(05)80254-3

Cited by 9 publications

(5 citation statements)

References 13 publications

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“…Cotton bract PAs induced the release of platelet serotonin and stimulated platelet aggregation in the absence of any other inducers, a mechanism which could contribute to the pulmonary symptoms associated with byssinosis in cotton workers 325. 326 However, these agonist effects may not be confirmed in vivo for the following reasons: the doses were much higher (260 µ M catechin equivalent) than those reasonably expected in the plasma; two PA dimers, the most bioavailable PAs, were ineffective;327 when platelet‐rich plasma was used in lieu of washed platelets, platelet activation was decreased over 50‐fold 328. On the contrary, the structurally related EGCG at a similar concentration (660 µ M ) did not activate platelets but inhibited their aggregation when induced by collagen, thrombin or the platelet activating factor 329…”

Section: Proanthocyanidins Tannin‐like Compounds and Prevention Of Cmentioning

confidence: 99%

Proanthocyanidins and tannin-like compounds - nature, occurrence, dietary intake and effects on nutrition and health

Santos‐Buelga

Scalbert²

2000

J. Sci. Food Agric.

1,063

712

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Proanthocyanidins (syn condensed tannins) are complex flavonoid polymers naturally present in cereals, legume seeds and particularly abundant in some fruits and fruit juices. They share some common structural features—phenolic nature and high molecular weight—with phenolic polymers found in black tea and red wine (called here tannin‐like compounds). The polymeric nature of proanthocyanidins makes their analysis and estimation in food difficult. For this reason, little is known about their consumption, although they likely contribute a large part of the daily polyphenol intake. They also share common physicochemical properties: they form stable complexes with metal ions and with proteins and are, like other polyphenols, good reducing agents. Many of their biological effects of nutritional interest derive from these properties. As metal ion chelators, they influence the bioavailability of several minerals. The nutritional significance of the non‐specific complexation of proteins is less clear. As reducing agents, they may participate in the prevention of cancers, both of the digestive tract and inner organs. They may also protect LDLs against oxidation and inhibit platelet aggregation and therefore prevent cardiovascular diseases. In vitro, animal and human studies on the prevention of these chronic diseases are reviewed with particular attention to wine and tea polyphenols. The lack of data on their bioavailability and the paucity of human studies are emphasised. © 2000 Society of Chemical Industry

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Section: Proanthocyanidins Tannin‐like Compounds and Prevention Of Cmentioning

confidence: 99%

Proanthocyanidins and tannin-like compounds - nature, occurrence, dietary intake and effects on nutrition and health

Santos‐Buelga

Scalbert²

2000

J. Sci. Food Agric.

1,063

712

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“…The active fraction was retained (data not shown), suggesting the active component formed large complexes in aqueous solution. Because polyphenols commonly form large, nondialyzable polymeric complexes in aqueous solution (31,32), and the immunomodulatory activity of many plant extracts resides in the polyphenol fraction (32, 33), we hypothesized that the broad activity profile from samples collected during the HPLC run may be from a group of polyphenolic complexes.…”

Section: Identification Of Plant Tannins As Agonists For ␥␦ T Cellsmentioning

confidence: 99%

Select Plant Tannins Induce IL-2Rα Up-Regulation and Augment Cell Division in γδ T Cells

Holderness

Jackiw

Kimmel

et al. 2007

The Journal of Immunology

118

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γδ T cells are innate immune cells that participate in host responses against many pathogens and cancers. Recently, phosphoantigen-based drugs, capable of expanding γδ T cells in vivo, entered clinical trials with the goal of enhancing innate immune system functions. Potential shortcomings of these drugs include the induction of nonresponsiveness upon repeated use and the expansion of only the Vδ2 subset of human γδ T cells. Vδ1 T cells, the major tissue subset, are unaffected by phosphoantigen agonists. Using FACS-based assays, we screened primary bovine cells for novel γδ T cell agonists with activities not encompassed by the current treatments in an effort to realize the full therapeutic potential of γδ T cells. We identified γδ T cell agonists derived from the condensed tannin fractions of Uncaria tomentosa (Cat’s Claw) and Malus domestica (apple). Based on superior potency, the apple extract was selected for detailed analyses on human cells. The apple extract was a potent agonist for both human Vδ1 and Vδ2 T cells and NK cells. Additionally, the extract greatly enhanced phosphoantigen-induced γδ T cell expansion. Our analyses suggest that a tannin-based drug may complement the phosphoantigen-based drugs, thereby enhancing the therapeutic potential of γδ T cells.

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“…Although we do not know what the minimum molecular mass for the effects of tannin actually are, one could assume that the minimum polymer length required for the effects of tannin on the ␤-adrenergic receptor and for the effects on adenylyl cyclase are between 6 and 11 monomer subunits. This monomer length is in contrast to the minimum tannin polymer length required for platelet 5-HT secretogogue activity, which is between 3 and 6 monomer units [18] but similar to the minimum requirement for stimulation of platelet thromboxane production [19]. Hence the minimum polymer length necessary for biological activity differs significantly between cells types and sometimes within cell types.…”

Section: Discussionmentioning

confidence: 82%

“…The tannin polymer is rich in hydroxyl groups, which are essential for the platelet agonist activity of tannin [18]. When the hydroxyl groups of tannin are methylated, tannin has no effect on platelet 5-HT release.…”

Section: Discussionmentioning

confidence: 99%

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Byssinosis: Role of Polymer Length on the Effect of Tannin on the Airway β-Adrenergic Receptor

Cloutier

Guernsey

1998

Lung

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Tannin, isolated from cotton bracts and implicated in the pathogenesis of byssinosis, inhibits isoproterenol and forskolin-stimulated cAMP release from airway cells in part by decreasing cell surface beta-adrenergic receptor number and uncoupling the beta-adrenergic receptor from its stimulatory G-protein (Gs) and in part by inhibiting adenylyl cyclase activity. We have hypothesized that cotton tannin, because of its long polymer length, interacts with the hydrophobic binding pocket of the beta-adrenergic receptor and alters beta-adrenergic receptor binding and Gs coupling. In these studies, tannins of three different polymer lengths and molecular masses were isolated from cotton bracts using sequential Amicon ultrafiltration [molecular mass > 10, 000 (YM10 retentate), 1,000-10,000 (YM10 filtrate), and 1,000-5,000 Da (YM2 retentate)]. The YM10 retentate (25 microg/ml) decreased chloride secretion (Jnet = 1.11 +/- 0.28 (control) to 0.59 +/- 0.18 microEq/cm2.h, p < 0.05, n = 6), decreased cell surface beta-adrenergic receptor number (18.0 +/- 1.8 (control) to 10.6 +/- 0.9 fmol/mg protein, p < 0.02, n = 4), and inhibited forskolin-stimulated cAMP release (5,254 +/- 1,290 (control) to 2, 968 +/- 620 pmol/mg protein, p < 0.01, n = 8). In contrast, neither the YM10 filtrate nor the YM2 retentate had any effect on net chloride secretion, beta-adrenergic cell surface receptor number, or forskolin-stimulated cAMP release. We conclude that polymer length is essential for the effect of tannin on the beta-adrenergic receptor and on adenylyl cyclase.

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Structural determinants of the platelet agonist activity of cotton bract condensed tannin

Cited by 9 publications

References 13 publications

Proanthocyanidins and tannin-like compounds - nature, occurrence, dietary intake and effects on nutrition and health

Proanthocyanidins and tannin-like compounds - nature, occurrence, dietary intake and effects on nutrition and health

Select Plant Tannins Induce IL-2Rα Up-Regulation and Augment Cell Division in γδ T Cells

Byssinosis: Role of Polymer Length on the Effect of Tannin on the Airway β-Adrenergic Receptor

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