In vitro analysis of iron chelating activity of flavonoids

Mladěnka, Přemysl; Macáková, Kateřina; Filipský, Tomáš; Zatloukalová, Libuše; Jahodár, L; Bovicelli, Paolo; Silvestri, Ilaria Proietti; Hrdina, Radomír; Saso, Luciano

doi:10.1016/j.jinorgbio.2011.02.003

Cited by 216 publications

(188 citation statements)

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“…Each CT molecule may bind two or more metal ions and each metal ion may form chelates with o-dihydroxyphenyl groups from two different CT molecules (McDonald et al, 1996). A 3',4'-dihydroxygroup on a flavonoid B-ring (Figure 6) is required for Fe binding (Khokhar and Owusu-Apenten, 2003) and increased free hydroxyl groups are associated with increased Fe-binding ability (Andjelkovic et al, 2006;Mladěnka et al, 2011).…”

Section: The Interactions Between Minerals and Condensed Tanninsmentioning

confidence: 99%

The role of condensed tannins in ruminant animal production: advances, limitations and future directions

et al. 2017

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-Tannins represent one of the most abundant polyphenolic compounds in plants. Tannins exist as a multitude of chemically unique entities in nature. The most commonly occurring tannins are typically divided into two major classes based on chemical structure: hydrolysable (HT) or condensed tannins (CT). Hydrolysable tannins are esters of gallic or ellagic acid linked to a polyol core, typically glucose. Condensed tannins or proanthocyanidins consist of flavan-3-ol subunits linked together to form oligomers and polymers. Both HT and CT are defined as astringent, medium-to-high-molecular weight polyphenolic compounds that characteristically bind and precipitate soluble proteins. The objective of this paper was to present recent advances in CT-ruminant interactions, the limitations associated with understanding and using CT in ruminant animal production, and future needs for research to further advance our knowledge of the role of CT in optimization of ruminant animal production. Condensed tannins pose some anti-nutritional problems to ruminants due to their astringent property that reduces feed intake and, consequently, animal performance. Ruminants can, however, tolerate CT by slowly adapting the ruminal microbes to the toxic effects of CT and by releasing CT-binding salivary proteins. The protein-binding ability of CT has some benefits to the ruminant due to complexes formed with essential amino acids, preventing their degradation in the rumen, but releasing them in the lower gut for absorption by the animal. Recent data have suggested increased N retention when CT is given to growing animals. There are potential benefits of using CT and HT for anthelmintic purposes due to their ability to inhibit egg hatching and larval motility of gastrointestinal nematode parasites, especially in small ruminants. Condensed tannins also bind to minerals (Al, Ca, Co, Cu, Fe, Mg, Mn, P, and Zn). Although studies with ruminants have been contradictory, it has been reported that because the CT-metal ion complex is stable over a wide pH range, CT may reduce the bioavailability of minerals. Methane mitigation by feeding CT might be the most impactful benefit for ruminant production. Many empirical equations have been developed to predict ruminal methane emissions, but very few have included CT. Future research should focus on the improvement of methodology to assess CT biological activity, interaction with other plant-specialized metabolites, and associated physiological and nutritional impacts on ruminants.

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Section: The Interactions Between Minerals and Condensed Tanninsmentioning

confidence: 99%

The role of condensed tannins in ruminant animal production: advances, limitations and future directions

et al. 2017

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“…The chelating activities can not be mainly attributed to the total polyphenol or flavonoid contents but rather to specific compounds of the extract with a favourable chemical structure to metal complexation. It was demonstrated that the most effective iron binding site of flavonoids represents 6,7-dihydroxy structure [22]. The 3-hydroxy-4-keto conformation together with 2,3-double bond and the catecholic B ring were associated also with a substantial iron chelation.…”

Section: Samplesmentioning

confidence: 99%

Flavonoid Content and Antioxidant Properties in Different Extracts of Calluna vulgaris (L.) Flowers

Dróżdż¹,

Sentkowska²,

Pyrzyńska³

2017

JAST-A

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This study evaluated the effect of four different solvent, i.e., water, ethanol, water-ethanol mixture and ethyl acetate, on the antioxidant activities of wild and cultivated heather (Calluna vulgaris (L.) Hull) plant. The highest values for total flavonoid content were obtained for samples extracted using ethanol-water mixture and ethyl acetate. Cupric reducing antioxidant capacity (CUPRAC) method, scavenging ability on 1,1-diphenyl-2-pirylhydrazyl radicals (DPPH) radicals and chelating activity on Fe 2+ ions have been used for evaluation of antioxidant activity of the extracts. Ethanolic fraction exhibited the lowest reducing capacity, despite a heather sample used. The extracts of cultivated heather exhibited significant scavenging effect on DPPH radicals, and ethanol and ethanol-water fractions were found to be the most effective. The metal-chelating effect of the extracts increased in the order: ethanol < ethyl acetate < ethanol-water < water. The results may be helpful for better utilization of heather flowers extracts as potential pharmaceutical and nutraceutical ingredient.

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“…Iron(II) is a primary cause of the ROS generation in vivo and plays a pivotal role in contributing to oxidative stress, DNA damage, and cell death, so it has been the target of many antioxidant therapies. By removing and neutralising prooxidative metals, polyphenols may prevent oxidative damage of important biomolecules due to highly reactive hydroxyl radicals generated by the Fenton reaction which is catalysed by Fe 2+ or Cu + ions (Mladenka et al, 2011;Perron & Brumaghim, 2009). Moreover, polyphenols may also act as preventive antioxidants through the inhibition of prooxidative enzymes, like xanthine oxidase (Selloum et al, 2001) which is a physiological source of superoxide anions in eukaryotic cells.…”

Section: Chemical-based Antioxidant Assaysmentioning

confidence: 99%