Environmental Mutagen Research

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ISSN / EISSN : 0910-0865 / 1880-7054
Total articles ≅ 29
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Yoshiaki Ito
Environmental Mutagen Research, Volume 27, pp 177-184; https://doi.org/10.3123/jems.27.177

Abstract:
The suppressive effect of (-)-epigallocatechin gallate (EGCG), the major polyphenolic constituent present in green tea, on 7,12-dimethylbenz[a]anthracene (DMBA)-induced chromosome aberrations (CA) in rat bone marrow cells was studied. Rats given EGCG before the DMBA injection displayed a considerably suppressed frequency of DMBA-induced CA in their bone marrow cells. The suppressive effect of EGCG (60 mg/kg body weight) given 24 h before was observed 24, 30, 48 and 72 h after the DMBA injection, but not at the early period (6, 12 and 18 h) after the DMBA treatment. On the other hand, EGCG (60 mg/kg body weight) given 0.5 h before DMBA suppressed DMBA-induced CA at all periods after the DMBA injection. The suppression of EGCG given 24 h or 0.5 h before was observed for all doses of DMBA (25, 50, 75 and 100 mg/kg) investigated. EGCG given at 60 mg/kg body weight 0.5 h before the DMBA injection showed greater suppressive effect than the same dose given 24 h before. The suppressive effect of EGCG given 0.5 h before was dosedependent in the range of 20-60 mg/kg body weight. Methyl methanesulfonate (MMS: direct-acting carcinogen)-induced CA were not suppressed by EGCG. The administration of dehydroepiandrosterone (DHEA), a typical substrate for hydroxysteroid sulfotransferases, 0.5 h before DMBA injection also significantly suppressed DMBA-induced CA but DHEA given 24 h before did not. These results suggest that EGCG has two different suppression mechanisms for DMBA-induced CA depending on the administration time. The suppression of DMBA-induced CA by EGCG given 24 h or 0.5 h before may result from the modification of microsomal enzyme system or the inhibition of sulfotransferase activity by EGCG, respectively.
, Toshihiro Ohta
Environmental Mutagen Research, Volume 27, pp 7-12; https://doi.org/10.3123/jems.27.7

Abstract:
Thiabendazole (TBZ), a post-harvest fungicide commonly used on imported citrus fruits, exhibited photo-mutagenicity following UVA-irradiation (320-400 nm) in Trp+ reverse mutation assay using Escherichia coli WP2uvrA/pKM101 strain. The photo-mutagenicity was not observed in the presence of S9 mix, a rat liver homogenate microsome fraction with co-factors for metabolic activation. We found that NADH and NADPH used as co-factor in the S9 mix efficiently suppressed the photo-mutagenicity of TBZ. This evidence strongly suggested that non-mutagenicity in the presence of S9 mix was not due to the metabolic detoxification of TBZ or the scavenging of UVA-activated TBZ by macromolecules in the S9 mix. Rather quenching effect of NADH and NADPH (λmax=338 nm) may be more responsible for suppression of UVA-activation of TBZ, because oxidized forms of NAD+ and NADP+ did not show inhibitory effects. Mutagenicity of the UVA-irradiated photo-mutagens such as angelicin and chlorpromazine was also suppressed by the addition of NADH or NADPH. Our present results suggest the possible underestimation in risk evaluation for photomutagenic compounds when they are assayed in the presence of S9 mix.
Tetsuya Hayashi
Environmental Mutagen Research, Volume 27, pp 117-118; https://doi.org/10.3123/jems.27.117

Abstract:
総合学術電子ジャーナルサイト「J-STAGE」-国内で発行された学術論文全文を読むことのできる、日本最大級の総合電子ジャーナルプラットフォームです。
Nor Fadilah Rajab, Zariyantey Abd. Hamid, Hunaizah Hassan, Abdul Manaf Ali, Laily B. Din, Salmaan H. Inayat-Hussain
Environmental Mutagen Research, Volume 27, pp 161-164; https://doi.org/10.3123/jems.27.161

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