title: Enhancing effect of heterocyclic amines and beta-carbolines on UV or chemically induced mutagenesis in E. coli.
abstract: Most heterocyclic amines and beta-carbolines--harman, norharman, harmine, harmaline--enhanced UVC (254 nm) induced mutagenesis without microsomal activation in E. coli B/r WP2. 3-Amino-1,4-dimethyl-5H-pyrido[4,3-b]indole (Trp-P-1) was most effective and increased UVAB (295-400 nm) induced mutations as well as UVC induced ones. Trp-P-1 enhanced the frequencies of mutations induced by not only UV but also 4-nitroquinoline-1-oxide (4NQO) or 2-(2-furyl)-3-(5-nitro-2-furyl)acrylamide (AF2), while it showed little effect on N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) or gamma-ray induced mutagenesis. Trp-P-1 decreased the survival of UVC irradiated cells of CM571recA. However, these effects of Trp-P-1 on UVC induced mutagenesis and lethality were not observed in WP2suvrA which is excision repair deficient. The alkaline sucrose gradient sedimentation analysis demonstrated that Trp-P-1 blocked the incision step in DNA excision repair. Further, pretreatment with Trp-P-1 before UVC irradiation showed no effect on UVC induced mutagenesis. Similar effects were also seen in the case of harman or norharman. These results suggest that heterocyclic amines and beta-carbolines inhibit DNA excision repair directly or indirectly, thus enhancing UV or chemically induced mutagenesis.
authors.affiliation: Laboratory of Health Science, School of Pharmaceutical Sciences, University of Shizuoka, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Shimoi
authors.forename: H
authors.initials: H
authors.lastname: Kawabata
authors.forename: I
authors.initials: I
authors.lastname: Tomita
mesh_terms: D000588:Amines / Q000494:pharmacology*; D002243:Carbolines / Q000494:pharmacology*; D002470:Cell Survival; D004260:DNA Repair / Q000187:drug effects*; D004926:Escherichia coli / Q000235:genetics*; D005720:Gamma Rays; D006571:Heterocyclic Compounds / Q000494:pharmacology*; D016296:Mutagenesis / Q000187:drug effects*; D009152:Mutagenicity Tests; D009153:Mutagens; D014466:Ultraviolet Rays
chemical_list: D000588:Amines; D002243:Carbolines; D006571:Heterocyclic Compounds; D009153:Mutagens; C019132:3-amino-1,4-dimethyl-5H-pyrido(4,3-b)indole