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From: ironjustice on 18 Jun 2008 09:46
"Polyphenols bind to iron for antioxidant activity"

Inorg Chem. 2008 Jun 14. [Epub ahead of print]
Predicting How Polyphenol Antioxidants Prevent DNA Damage by Binding
to Iron.
Perron NR, Hodges JN, Jenkins M, Brumaghim JL.
brumagh(a)clemson.edu.

Prevention of oxidative DNA damage due to hydroxyl radical is
important for the prevention and treatment of disease. Because of
their widely recognized antioxidant ability, 12 polyphenolic compounds
were assayed by gel electrophoresis to directly quantify the
inhibition of DNA damage by polyphenols with Fe (2+) and H 2O 2. All
of the polyphenol compounds have IC 50 values ranging from 1-59 microM
and inhibit 100% of DNA damage at 50-500 microM concentrations. Gel
electrophoresis results with iron(II)EDTA and UV-vis spectroscopy
experiments confirm that binding of the polyphenol to iron is
essential for antioxidant activity. Furthermore, antioxidant potency
of polyphenol compounds correlates to the p K a of the first phenolic
hydrogen, representing the first predictive model of antioxidant
potency based on metal-binding. Understanding this iron-coordination
mechanism for polyphenol antioxidant activity will aid in the design
of more-potent antioxidants to treat and prevent diseases caused by
oxidative stress, and help develop structure-activity relationships
for these compounds.

PMID: 18553907 [PubMed - as supplied by publisher]
--------------------------------

J Agric Food Chem. 2008 Jun 11. [Epub ahead of print] Links
Iron Bioavailability to Piglets from Red and White Common Beans
(Phaseolus vulgaris).Tan SY, Yeung CK, Tako E, Glahn RP, Welch RM, Lei
X, Miller DD.
ddm2(a)cornell.edu.

Polyphenols in foods may chelate dietary Fe and lower its
bioavailability. Concentrations of phenols are higher in red beans
than in white beans. The aim of this study was to compare iron
bioavailabilities from red and white beans in a piglet hemoglobin
repletion model. Fe deficient cross bred piglets (Hampshire x Landrace
x Yorkshire) were used. Nutritionally balanced diets (except for Fe)
were formulated to contain 50% precooked, dehydrated beans (either
small red or Great Northern white). At age 5 weeks, the piglets were
assigned to two groups and fed diets containing either red or white
beans for 4 weeks. Weight and hemoglobin (Hb) concentrations were
monitored weekly. Feed intakes were measured daily. Hemoglobin
repletion efficiency (HRE) was calculated as the gain in total body
hemoglobin Fe (Hb-Fe) divided by Fe intake. Hb concentrations, Hb-Fe
gains, and HRE were not different between the groups at any time point
( p > 0.05). HRE values in the red bean group were 50% in the first
week and 30% over the entire 4 week period. In the white bean group,
they were 56 and 26%, respectively. Proline-rich protein mRNA
concentrations in parotid glands were higher in the red bean group
compared to the white bean group. These results show that iron
bioavailabilities from red and white beans are similar and suggest
that pigs adapt to the inhibitory effects of polyphenols on iron
absorption by increasing the secretion of protective proline-rich
proteins in the saliva.

PMID: 18543933 [PubMed - as supplied by publisher]
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