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Authors
Komatsu K. Kator K. Mitsuda Y. Mine M. Okumura Y.
Institution
Department of Radiation Biophysics, Nagasaki University School of Medicine,
Japan.
Title
Inhibitory effects of Rooibos tea, Aspalathus linealis, on
X-ray-induced C3H10T1/2 cell transformation.
Source
Cancer Letters. 77(1):33-8, 1994 Feb 28.
Abstract
Oncogenic transformation of mouse C3H10T1/2 cells induced by X-rays was
suppressed in the presence of extract of Rooibos tea,
Aspalathus linealis. Transformation was reduced with increased concentration
of the extract, so that at an extract concentration of 10%, transformation
incidence was similar to the spontaneous level. Suppression was also
dependent on treatment time with the extract and was maximal when present
during the entire incubation period. In contrast, green tea extract at an
equitoxic concentration showed no detectable effect on transformation
incidence.
<2>
Unique Identifier
93211427
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.