Tumor promoting effect of N-nitroso-N-(2-hexanonyl)-3 '-nitrotyramine (a nitrosated Maillard reaction product) in benzo(a)pyrene-initiated mouse skincarcinogenesis

N-nitroso-N-(2-hexanonyl)-3'-nitrotyramine (NO-HNTA) is a product generated in a. model browning system in the presence of sodium nitrite. The chemica l structure of this compound has been confirmed by UV, mass, nuclear magnet ic resonance and infrared spectroscopy in our study. Twenty weeks, twice we ekly, topical application of NO-HNTA at the concentration of 10, 50 and 250 mu mol to mice previously initiated with benzo(a)pyrene (B[a]P) increased their tumor formation by 3.2-, 4.6- and 5.8-fold respectively. Application of the same amount of NO-HNTA not only caused significant induction of hype rplasia but also the activity of epidermal ornithine decarboxylase (ODC). T reatment of mouse skin with various amounts of NO-HNTA (10, 50 and 250 mu m ol) caused production of hydrogen, peroxide by 1.38-, 1.95- and 3.26-fold r espectively, and induction myeloperoxidase (MPO) by 24-, 63- and 102-fold. These results indicate that the formation of NO-HNTA or its derivatives der ived from the reaction of tyrosine and glucose in the presence of sodium ni trite has the potential as a tumor promoter. (C) 1998 Elsevier Science Irel and Ltd. All rights reserved.