In recent years, there have been considerable efforts to search for naturally occurring substances for intervention of
carcinogenesis. Many components from medicinal or dietary plants have been identified to possess potential chemopreventive properties. For instance,
curcumin, a yellow colouring agent from turmeric (Curcuma longa Linn., Zingiberaceae) has been shown to inhibit
tumor formation in diverse animal models. Alpinia oxyphylla Miquel that also belongs to ginger family has been used in oriental herbal medicine. In the present work, we have evaluated the anti-
tumor promoting potential of
yakuchinone A (1-[4'-hydroxy-3'-methoxyphenyl]-7-phenyl-3-heptanone) and
yakuchinone B (1-[4'-hydroxy-3'-methoxyphenyl]-7-phenylhept-1-en-3-one), major pungent ingredients of A. oxyphylla. Thus, topical application of
yakuchinone A or B significantly suppressed TPA-induced epidermal
ornithine decarboxylase activity. They also reduced TPA-stimulated production of
tumor necrosis factor-alpha in cultured human promyelocytic
leukemia (HL-60) cells. Both compounds blunted the TPA-induced
superoxide generation in differentiated HL-60 cells in a concentration-related manner and also inhibited lipid peroxidation in rat brain homogenates. Furthermore,
yakuchinone A and
yakuchinone B nullified the activation of the
activator protein-1 (AP-1) in immortalized mouse fibroblast cells in culture. These findings indicate that pungent
diarylheptanoids from A. oxyphylla have anti-
tumor promotional properties that can contribute to their chemopreventive potential.