From: Doug Skrecky (oberon@vcn.bc.ca)
Date: Thu Apr 22 1999 - 22:11:31 MDT
Citations: 1-4
<1>
Authors
Shimoi K. Masuda S. Shen B. Furugori M. Kinae N.
Institution
Laboratory of Food Hygiene, School of Food and Nutritional Sciences,
University of Shizuoka, Japan.
Title
Radioprotective effects of antioxidative plant flavonoids in mice.
Source
Mutation Research. 350(1):153-61, 1996 Feb 19.
Abstract
Radioprotective effects of tea infusions and plant flavonoids were
investigated by using the micronucleus test for anticlastogenic activity and
the thiobarbituric acid assay for antioxidative activity. A single gastric
intubation of rooibos tea (Aspalathus linearis) infusion at
1 ml per mouse 2 h prior to gama-ray irradiation (1.5 Gy) reduced the
frequency of micronucleated reticulocytes (MNRETs). After the fractionation
of rooibos tea infusion, the flavonoid fraction was found to
be most anticlastogenic and antioxidative. From this fraction, luteolin was
isolated as an effective component. Then, anticlastogenic effects of 12
flavonoids containing luteolin and their antioxidative activities against
lipid peroxidation by Fenton's reagent were examined. A good correlation
(r=0.717) was observed between both activities. Luteolin showed the most
effective potency. A gastric intubation of luteolin (10 micromoles/kg) 2 h
prior to gamma-ray irradiation (6 Gy) suppressed lipid peroxidation in mouse
bone marrow and spleen and a trend of protective effect of luteolin against
the decrease of endogenous ascorbic acid in mouse bone marrow after gamma-ray
irradiation (3 Gy) was observed. These results suggest that plant flavonoids,
which show antioxidative potency in vitro, work as antioxidants in vivo and
their radioprotective effects may be attributed to their scavenging potency
towards free radicals such as hydroxyl radicals. Therefore, the flavonoids
contained in tea, vegetables and fruits seem to be important as antioxidants
in the human diet.
<2>
Authors
Inanami O. Asanuma T. Inukai N. Jin T. Shimokawa S. Kasai N. Nakano M.
Sato F. Kuwabara M.
Institution
Faculty of Agriculture, Iwate University, Morioka, Japan.
Title
The suppression of age-related accumulation of lipid peroxides in rat brain
by administration of Rooibos tea (Aspalathus linearis).
Source
Neuroscience Letters. 196(1-2):85-8, 1995 Aug 18.
Abstract
The protective effects of Rooibos tea (RT), Aspalathus
linearis, against damage to the central nervous system (CNS) accompanying
aging were examined by both the thiobarbituric acid reaction (TBA) and
magnetic resonance imaging (MRI) methods in brains of chronically RT-treated
rats. Ad libitum administration of RT was begun with 3-month-old Wistar
female rats and continued for 21 months. The contents of TBA reactive
substances (TBARS) in the frontal cortex, occipital cortex, hippocampus and
cerebellum in 24-month-old rats after administration with water were
significantly higher than those in young rats (5 weeks old). However, no
significant increase of TBARS was observed in RT-administered aged rats. When
MR images of the brains of 24-month-old rats with and without RT as well as
5-week-old rats were taken, a decrease of the signal intensity was observed
in the cerebral cortex, hippocampus and cerebellum in MR images of aged rats
without RT, whereas little change of the signal intensity was observed in MR
images of the same regions of 24-month-old rats treated with RT, whose images
were similar to those of young rats. These observations suggested that (1)
the age-related accumulation of lipid peroxides in the brain was closely
related to the morphological changes observed by MRI, and (2) chronic
RT-administration prevented age-related accumulation of lipid peroxides in
several regions of rat brain.
<3>
Authors
Sasaki YF. Yamada H. Shimoi K. Kator K. Kinae N.
Institution
Laboratory of Food Hygiene, School of Food and Nutritional Sciences,
University of Shizuoka, Japan.
Title
The clastogen-suppressing effects of green tea, Po-lei tea and
Rooibos tea in CHO cells and mice.
Source
Mutation Research. 286(2):221-32, 1993 Apr.
Abstract
The suppressing effects of crude extracts of three kinds of tea-green tea
(GT) from Japan, Po-lei tea (PT) from China, and Rooibos tea
(RT) from South Africa-on the induction of chromosome aberrations in cultured
CHO cells and mice were studied. When CHO cells were exposed to each tea
extract in the presence of rat liver microsomal enzymes (S9 mix) together
with benzo[a]pyrene (B(a)P) or mitomycin C (MMC), a decrease in the frequency
of chromosome aberrations was observed. PT and RT, but not GT, also
suppressed the induction of chromosome aberrations by MMC in the absence of
S9 mix. When cells were treated with tea extract after B(a)P or MMC
treatment, RT suppressed the induction of chromosome aberrations in the
presence and absence of S9 mix whereas GT and PT showed suppressing effects
only in the presence of S9 mix. These data suggest that catechines,
well-known antimutagens in tea samples, might account for the inhibitory
effect in the case of GT and PT. Since RT contains few catechines, several
unknown antimutagenic components could be responsible for its effect. The
antimutagenic effects of tea extracts at concentration levels consumed by
humans were examined in mice using micronucleus induction with B(a)P or MMC.
When mice received oral gavage of 0.2% GT, 0.1% PT, and 0.1% RT at 1.0
ml/mouse 6 h before intraperitoneal injection of MMC, a decrease in the
frequency of micronuclei was observed. The induction of micronuclei by B(a)P
was suppressed by oral dosage of GT, PT and RT at 1.0 ml/mouse/day for 28
days. This was not due to a delay in the maturation of micronucleated
reticulocytes. In conclusion, intake of tea might suppress the mutagenic
activity of certain potent mutagens in human beings.
<4>
Authors
Hesseling PB. Klopper JF. van Heerden PD.
Title
[The effect of rooibos tea on iron absorption]. [Afrikaans]
Source
South African Medical Journal. 55(16):631-2, 1979 Apr 14.
Abstract
A study was carried out to determine if rooibos tea
(Aspalathus linearis) has a deleterious effect on iron absorption similar to
that of ordinary tea (Camellia sinensis). Three groups of volunteers, each
consisting of 10 healthy young men comparable with regard to iron status and
body dimensions, were studied. After ingestion of 1 muCi 59Fe and 16 mg of
elemental iron, group A drank rooibos tea, group B ordinary
tea and group C boiled water. Iron absorption was measured 14 days later with
a whole body counter. Mean iron absorption after ingestion of
rooibos tea, ordinary tea, and water was 7,25%, 1,70% and
9,34% respectively. In contrast to ordinary tea (P less than 0,0001),
rooibos tea did not affect iron absorption significantly.
The ascorbic acid content of rooibos tea varies between
121,8 and 154,9 mumol/l, depending on the method of preparation.
Rooibos tea contains small amounts of iron, magnesium,
phosphorus, sodium, chloride and potassium. These findings have practical
nutritional and therapeutic implications.
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