Modification of SCEs and chromosome aberrations by tea tannin components in mutagen-treated cultured mammalian cells

273 $9 mix after nitrite treatment under acidic conditions and their mutagenicities were decreased by $9 mix. Methanol extracts of radish, dissolved in 10 volumes of water, were treated with 40 mM NaNO 2 at pH 3 for 1 h at 37 °C in the dark. The reactions were stopped by adding ammonium sulfamate, and the mutagenicities were then examined by the preincubation method. Pickled smoke-dried radish and dried radish from China showed high mutagenicities among samples which were tested on WP2uvrA/pKMlO1 (18300 and 23600 T r p + / g wet wt, respectively). Dried radishes from Thailand and China showed high mutagenicity among samples tested on TA98 (4250 and 3080 His+/g), whereas those from Japan and China showed high mutagenicity among samples tested on TA100 (3190 and 5110 His+/g). Fresh radish showed mutagenicities of 70, 500 and 520 Rev+/g on TA98, TA100 and WP2uvrA / pKM101, respectively. Indole glucocinolates (glucobrassicins) are present in high concentrations in cruciferous plants. Therefore, radish may produce indole compounds by enzymatic or chemical hydrolysis of glucocinolates during processing. These indole compounds, such as indole-3-acetic acid and indole-3-acetonitrile, all become mutagenic on treatment with nitrite. Grated radish showed higher mutagenicity than fresh radish.

induction of SCEs and chromosome aberrations by mutagens were complicated. MMC- and UVinduced SCEs and chromosome aberrations were suppressed by posttreatment with tea tannin components at low concentrations ( < 6.7/xg/ml) with $9 mix. At a high concentration of tea tannin components (20/xg/ml) with $9 mix, a co-mutagenic effect was observed. In cells from a patient with XP and a normal human embryo, MMC-induced SCEs were suppressed by posttreatment with tea tannin components in the presence of $9 mix, and were enhanced in the absence of $9 mix. On the other hand, tea tannin components modified SCE frequencies in UV-irradiated normal human cells but not in UV-irradiated XP cells. Our results suggested that tea tannin components themselves inhibited DNA-excision repair and resuited in a co-mutagenic effect, while in the presence of $9 mix metabolites of tea tannin components promoted DNA-excision repair activity and resulted in an antimutagenic effect.

73 Sasaki, Y.F., H. Matsumura, T. Ohta and Y. Shirasu, Institute of Environmental Toxicology, Suzuki-cho 2-772, Kodaira, Tokyo 187 (Japan)

Phthalic acid esters (PAEs) are used mainly as plasticizers for polyvinyl chloride and are found widely in the environment. We investigated their modification of chemical mutagenesis. Twenty PAEs including 3 mono-esters were evaluated with Salmonella typhimurium TA98 and Trp-P-1 and Trp-P-2 as mutagens, and 13 PAEs including 2 mono-esters such as phthalic acid, di-isopropyl phthalate, di-n-octyl phthalate, enhanced the mutagenicity more than 2-fold. Di-isopropyl phthalate showed the strongest enhancing activity, that is, it showed a 2-fold enhancing effect at the lowest concentration (0.054/zmole/plate) of the PAEs. Five PAEs (phthalic acid, di-isopropyl phthalate, di-n-octyl phthalate, DEHP, MEHP) were also investigated for their effect using 4NQO and 2-nitrofluorene (2-NF) as direct mutagens,

Modification of SCEs and chromosome aberrations by tea tannin components in mutagentreated cultured mammalian cells The modifying effects of tannin components extracted from green tea and black tea on mutagen-induced SCEs and chromosome aberrations were studied. MMC- or UV-induced SCEs and chromosome aberrations were enhanced by posttreatment with tea tannin components. When cells were posttreated with tea tannin components in the presence of $9 mix, modifying effects on the

74 Sato, K., T. Sato, H. Nagase, H. Kito and K. Chikazawa, Department of Public Health, Gifu Pharmaceutical University, 5-6-1 Mitahora-higashi, Gifu 502 (Japan) Modification of chemical mutagenesis by phthalic acid esters