T. Isbir et al., The effects of Brassica oleraceae var capitata on epidermal glutathione and lipid peroxides in DMBA-initiated-TPA-promoted mice, ANTICANC R, 20(1A), 2000, pp. 219-224
Background: The objective of the present study was to determine if modulati
on of GSH-dependent antioxidant protective system by Brassica oleraceae var
capitata might inhibit the molecular mechanism of skin tumor promotion. Ma
terials and Methods: In a two stages skin carcinogenesis model the protocol
used included a single topical application of 200 nmol of the initiator 7,
12-dimethyl-benz(a)anthracene (DMBA) to the backs of mice, followed I week
later by promotion with 10 nmol of 12-O-tetradecanoyl-phorbol-13 acetate (
TPA) twice weekly for 30 weeks. In addition to this regimen, 0.1 g/L brassi
ca extract was added water week prior to the initiating dose of DMBA in the
treatment group. Tissue glutathione (GSH) contents and levels of lipid per
oxidation products (measured as thiobarbituric acid (TBA)-reactive substanc
es) were quantitated in the skin tumors generated by the initiation-promoti
on protocol. Results: It was observed that the tumor incidence and tumor mu
ltiplicity in the treatment group was highly significantly low compared to
the first group of mice (p <0.001 and p <0.001, respectively). In! the trea
tment group, GSH content in the papillomas was higher than in the non-invol
ved skin surrounding the papillomas. Conclusions: We suggest that the antic
arcinogenicity of Brassica may be linked to its ability to facilitate or en
hance the activity of the natural GSH-dependent antioxidant protective syst
em of the epidermal cells during the later stages of skin tumor promotion.