Anti-tumor promoting potential of naturally occurring diarylheptanoids structurally related to curcumin

In recent years, there have been considerable efforts to search for natural ly 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 age nt from turmeric (Curcuma longa Linn., Zingiberaceae) has been shown to inh ibit tumor formation in diverse animal models. Alpinia oxyphylla Miquel tha t also belongs to ginger family has been used in oriental herbal medicine. In the present work, we have evaluated the anti-tumor promoting potential o f 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), ma jor pungent ingredients of A. oxyphylla. Thus, topical application of yakuc hinone A or B significantly suppressed TPA-induced epidermal ornithine deca rboxylase activity. They also reduced TPA-stimulated production of tumor ne crosis factor-alpha in cultured human promyelocytic leukemia (HL-60) cells. Both compounds blunted the TPA-induced superoxide generation in differenti ated HL-60 cells in a concentration-related manner and also inhibited lipid peroxidation in rat brain homogenates. Furthermore, yakuchinone A and yaku chinone B nullified the activation of the activator protein-1 (AP-1) in imm ortalized mouse fibroblast cells in culture. These findings indicate that p ungent diarylheptanoids from A. oxyphylla have anti-tumor promotional prope rties that can contribute to their chemopreventive potential. (C) 1999 Else vier Science B.V. All rights reserved.