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for Fundamental Research, Suntory Research Center, Mishima-gun, Osaka 618, 2 School of Pharmaceutical Science, University of Sizuoka, Yada, Shizuoka 422 and 3 Carcinogenesis Divi- sion, National Cancer Center Research Institute, Chuo-ku, Tokyo 104 (Japan)

Development of a nitrite scavenger applying indi- gestible polymers

N-Nitrosamine formation by the reaction of secondary amines and nitrite in some foodstuffs is well known. At the annual meeting of the Japanese Cancer Association in 1990, we re- ported the strong inhibitory effect of p-amino- benzoic acid (PABA) on the formation of muta- genicity of some foodstuffs in the presence of nitrite. PABA seemed to scavenge nitrite ion by producing p-aminohydroxybenzoic acid (PHBA) and N 2 which are non-mutagenic. However, we found that PABA increased the mutagenicities of a few foodstuffs with nitrite treatment. There- fore, the application of PABA as a nitrite scav- enger is not adequate for human use. Moreover, it has been shown that the nitrite ion has some important physiological functions in the human body, such as killing bacteria by macrophages. Therefore, we think that indigestible nitrite scav- engers which react only in the alimentary tract should be developed.

In this study, we tried to develop a safer nitrite scavenger by conjugating PABA with an indi- gestible polymer (EAH Sepharose 4B). PABA- conjugated EAH Sepharose 4B (PCES) was pre- pared by coupling the carboxyl group from PABA to free amino groups of EAH Sepharose 4B using the carbodiimide method. The nitrite-scavenging effects of this polymer were determined with the Ames Salmonella assay using TA100 without $9 mix. As a result, PCES, at a concentration 1/10 of that of nitrite, completely suppressed the mu- tagenicities of soy sauce and Ban-Ban-chi sauce induced with nitrite treatment. Furthermore, PCES inhibited the mutagenicities of soybean flour and bloater induced with nitrite treatment by 40-50%. But neither PABA nor EAH Sepharose 4B alone was effective at a concentra- tion 1/10 of that of nitrite. Since PCES did not enhance the mutagenicities of any foodstuffs, un-

like PABA, it is concluded that application of PCES as a nitrite scavenger for human use seems to be safer than that of PABA.

20 Hayashi, J., S. Aso, K. Kusakabe, S. Morooka, H. Tokiwa 1, K. Horikawa l and N. Sera ~, Depart- ment of Applied Chemistry, Kyushu University, 6-10-1, Higashi-ku, Fukuoka 812 and ~ Fukuoka Environmental Research Center, Dazaifu 818-01 (Japan)

Effect of preozonation on reduction of mutagenic activity of chlorinated humic acids in water

An aqueous solution containing humic sub- stances was ozonated and then chlorinated by adding HC10. The solution was passed through a column of XAD-2 adsorbent, and the hydropho- bic component was recovered and subjected to the Salmonella/microsome mutagenicity assay with S. typhimurium strains TA98 and TA100 (Maron et al., Mutation Res., 113 (1983) 173-215). The mutagenic activity of the chlorinated solu- tion, defined as the number of revertants per unit volume of solution, was dependent on the TOC removal yield by preozonation. In the range where the TOC removal yield was lower than 5% of the initial TOC, the mutagenic activity increased. When the TOC reduction by preozonation ex- ceeded 5%, however, the activity decreased with increasing TOC removal yield. When the TOC was destroyed by 50%, the activity was lowered to 1/30 of the initial value. Thus the preozonation destroyed precursors of organic halides, and it was also found that preozonation was very effec- tive for the selective reduction of the XAD-2 component which was a major mutagenic part of the total organic halides.

21 Hayashi, M., T. Suzuki, A. Matsuoka and T. Sofuni, Division of Genetics and Mutagenesis, Biological Safety Research Center, National In- stitute of Hygienic Sciences, 1-18-1, Kamiyoga, Setagaya-ku, Tokyo 158 (Japan)