Carcinogenesis, Vol 18, 1911-1916, Copyright © 1997 by Oxford University Press
SK Katiyar and H Mukhtar
Over the past 10 years many studies from several laboratories defined
anticarcinogenic and anti-inflammatory effects of tea, a widely consumed
beverage by the human population. Much of such work has been conducted with
green tea or its polyphenolic constituents. Regarding black tea, studies
have shown that its water extract affords protection against tumor
promotion caused by chemical carcinogens or ultraviolet B radiation in
murine skin carcinogenesis models. Several studies have shown that topical
application of chemical tumor promoters to murine skin results in the
induction of epidermal edema, hyperplasia and ornithine decarboxylase (ODC)
and cyclo-oxygenase activities, and interleukin-1 alpha (IL-1alpha) and ODC
mRNA expression. In this study, we assessed whether topical application of
polyphenols isolated from black tea leaves (hereafter referred to as BTP)
mainly consisting of theaflavine gallates and
(-)-epigallocatechin-3-gallate, inhibits phorbol ester tumor promoter
12-O-tetradecanoylphorbol-13-acetate (TPA)- caused induction of these
markers of inflammatory responses in murine skin. Topical application of
BTP (6 mg in 0.2 ml acetone/animal) 30 min prior to TPA application on to
the mouse skin resulted in significant inhibition against TPA-caused
induction of epidermal edema (40%, P < 0.01), hyperplasia (57%, P <
0.005), leukocytes infiltration (50%), and induction of epidermal ODC (57%)
and pro-inflammatory cytokine IL- 1alpha mRNA expression (69%).
Pre-application of BTP to that of TPA also resulted in significant
inhibition of TPA-caused induction of epidermal ODC (23-73%, P <
0.005-0.0001), and cyclo-oxygenase, in terms of prostaglandins metabolites
formation (38-65%, P < 0.01-0.0005), enzyme activities. Our data
indicate that the inhibition of TPA-caused changes in these markers of
inflammatory responses in murine skin by BTP may be one of the possible
mechanisms of chemopreventive effects associated with black tea against
tumorigenesis. The results of this study suggest that black tea,
specifically polyphenols present therein, may be useful against cutaneous
inflammatory responses in human population.
ARTICLES
Inhibition of phorbol ester tumor promoter 12-O-tetradecanoylphorbol-13- acetate-caused inflammatory responses in SENCAR mouse skin by black tea polyphenols
Department of Dermatology, University Hospitals of Cleveland, Case Western Reserve University, OH 44106, USA.
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