Affiliations: Laboratory of Biochemistry and Molecular Toxicology,
College of Pharmacy, Seoul National University, South Korea
Note: [] Address for correspondence: Professor Young-Joon Surh, College
of Pharmacy, Seoul National University, Shinlim-dong, Kwanak-ku, Seoul 151-742,
Korea. Tel.: +82 2 880 7845; Fax.: +82 2 874 9775 or +82 2 872-1795; E-mail:
surh@plaza.snu.ac.kr
Abstract: Cancer bush (CB, Sutherlandia frutescens), Devil's claw (DEV,
Harpagophytum procumbens), Rooibos tea (RT, Aspalathus linearis),
and Bambara groundnut (BB, Vignea subterranean) have been used to treat
some malignancies and inflammatory disorders in Africa. However, biochemical
basis for chemopreventive effects of these medicinal plants remains unclear. An
abnormally elevated expression of cyclooxygenase-2 (COX-2) has been implicated
in pathogenesis and progression of carcinogenesis. In the present study, we
found that the methanol extracts of CB, DEV, RT, and BB inhibited, to a
different extent, 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced COX-2
expression in human breast epithelial (MCF10A) cells and in mouse skin in
vivo. To determine the molecular mechanism of COX-2 inhibition by the above
medicinal plants, we examined their effects on activation of
NF-κB which is one of the major transcription factors
responsible for regulating COX-2 expression. Methanol extracts of both CB and
BB inhibited the DNA binding of NF-κB activated by TPA
in MCF10A cells in a dose-dependent manner. Based on above findings, CB and BB
are likely to inhibit TPA-induced COX-2 expression through suppression of DNA
binding of NF-κB, which may contribute to the
chemopreventive or chemoprotective activity of these African plants.
