Inhibitory effect of methyl caffeate on fos-jun-DNA complex formation and suppression of cancer cell growth

The fos and jun proteins form a heterodimeric complex that interacts with t he DNA regulatory element known as the AP-1 binding site. To search for inh ibitors of the fos-jun-DNA complex formation, several natural plants extrac ts were screened. One of them, the methanol extract of Perilla frutescens s howed inhibitory effect against the complex formation between the fos-jun d imer and the AP-1 binding site (TGAG/CTCA). Methyl caffeate and dibutyl pht halate (DBP) were isolated as the active constituents from the extract of P . frutescens by repeated column chromatography and HPLC. And their IC50 val ues for fos-jun-DNA complex formation were estimated as 0.29 mM and 0.55 mM , respectively. The more potent inhibitor, methyl caffeate showed cytotoxic effect against human cancer cell line (A549 and K562).