@article {1691,
	title = {Quantifying Oxidant-Scavenging Ability of Blood},
	journal = {The New England Journal of Medicine},
	volume = {364},
	number = {9},
	year = {2011},
	pages = {883-885},
	abstract = {Screening the voluminous literature
describing the quantifications of antioxidant
levels in patients with various clinical disorders
and after the administration of supplements has
revealed that nearly all the studies have exclusively
involved measurements in plasma. Since the classic
tests have mainly quantified levels of low-molecular-
weight antioxidants and albumin in human
plasma but not those associated with erythrocyte
enzymes and hemoglobin, such studies have not
taken into account the roles of circulating cells,
all laden with catalase and additional enzymes.
This finding raises serious doubt as to whether
reports on antioxidant quantifications exclusively
in plasma can be trusted to represent true
oxidant-scavenging abilities. Using a new chemiluminescence
assay and an assay involving the
free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH)
(which are adapted to quantify antioxidants in
whole blood),1 we have shown that erythrocytes,
platelets, and lymphocytes not only rapidly scavenge
reactive oxygen species but also avidly bind
to their surfaces a large variety of antioxidant
polyphenols, which further enhance their oxidantscavenging
abilities.2,3 Such complexes could further
act synergistically with low-molecular-weight
antioxidants in plasma and with albumin to
decompose reactive oxygen species. The synergistic
scavenging effect of reactive oxygen species
can be induced by a combination of human
erythrocytes, plasma, and the representative polyphenol,
epicatechin (Fig. 1).
The advantage of the luminescence assay over
the other classic methods is that it can quantify
antioxidants in whole blood and that only 2 to
3 mm3 are needed to rapidly assess its oxidantscavenging
ability. As proposed by Richards et al.4
and by Minetti and Malorni,5 erythrocytes have
potent antioxidant properties that can act as sinks
and as protectors against reactive oxygen species
but may also act as pro-oxidant cells. It has been
suggested that the genuine oxidant-scavenging
ability of blood is most probably a result of the
synergistic effects exerted by the antioxidants
associated with blood cells, mostly due to catalase,
superoxide dismutase, glutathione peroxidase,
oxidoreductase, and hemoglobin, cells that
are coated in an accumulative manner by dietary
polyphenols, free circulating polyphenols, and
low-molecular-weight antioxidants and albumin
in plasma.2,3 The ability of blood cells to bind
antioxidant polyphenols may be an important
phenomenon with far-reaching in vivo consequences.
With all these factors taken together,
it is paramount that antioxidants be measured
in whole blood and not in plasma alone in
clinical settings.},
	author = {Isaac Ginsburg and Ron Kohen and Erez Koren}
}
