Biology Reference
In-Depth Information
using the FRAP assay (Halvorsen
et al.
, 2002). Interestingly, dietary
plants with high ellagitannin content are well represented among those
with the highest level of total antioxidants (see Fig. 8.5 for the 20 best
antioxidant sources).
Less is known about the effects of consumption of ellagitannin-rich
foods on the antioxidant status
in vivo
. In elderly women, the total
antioxidant capacity of serum increased by about 10% during the 4-hour
period after consumption of 240 g of strawberries (Cao
et al.
, 1998). A
single dose of standardized pomegranate extract (Mertens-Talcott
et al
.,
2006a) and long-term consumption of pomegranate juice (Rosenblat
et al.
, 2006) also improved several antioxidant parameters in human
volunteers. However, the daily consumption of walnuts for three weeks
had no effect on the antioxidant status of subjects with metabolic
syndrome (Davis
et al.
, 2007).
8.4.2 Inhibition of growth of human pathogenic microbes
Phenolic extracts of many berries inhibit the growth of human
pathogenic microbes
in vitro.
Among all the berries studied, berries with
high contents of ellagitannins,
i.e.
, cloudberries, raspberries and
strawberries appear the most promising, showing antimicrobial activity
against
Salmonella
,
Escherichia coli
,
Bacillus cereus
,
Campylobacter
jejuni
,
Clostridium perfringens
,
Helicobacter pylori
,
Staphylococcus
aureus
,
Staphylococcus epidermis
and
Candida albicans
,
but not against
beneficial probiotic lactic acid bacteria (Puupponen-Pimiä
et al
., 2001,
2005a/b, Nohynek
et al.
, 2006).
Campylobacter jejuni
and
Candida
albicans
are sensitive only to these berries.
Bacillus cereus
,
Clostridium
perfringens
and
Staphylococcus aureus
cause food poisonings by
producing toxins in food, and
Salmonella
,
Escherichia coli
and
Campylobacter jejuni
cause gastrointestinal infections.
Helicobacter
pylori
infection may lead to chronic gastritis, peptic ulcer and stomach
cancer.
Staphylococcus aureus
and
Staphylococcus epidermis
are found
in normal flora of human skin, but may cause diseases from minor skin
infections to severe life-threatening infections in patients with impaired
immune system.
Candida albicans
is present in normal human flora, but
