title: Humic acids inhibit the formation but not the mutagenicity of N-methyl-N-nitrosourea.
abstract: Humic acids in the form of potassium humate (KH), at concentrations exerting a strong inhibitory effect on the formation of N-methyl-N-nitrosourea (MNU) when present during the nitrosation of N-methylurea (MU) at pH 3, did not reduce the mutagenicity of preformed MNU in Tradescantia, clone 4430. The inhibitory effect of 20 mg/ml KH corresponds approximately to that of 3.75 mM (0.66 mg/ml) ascorbic acid towards the formation of MNU from the mixture of 7.5 mM MU + 7.5 mM NaNO2.
authors.affiliation: Institute of Chemical Physics, Academy of Sciences, Moscow, U.S.S.R.
authors.forename: S A
authors.initials: SA
authors.lastname: Badaev
authors.forename: T
authors.initials: T
authors.lastname: Gichner
authors.forename: F
authors.initials: F
authors.lastname: Pospísil
authors.forename: J
authors.initials: J
authors.lastname: Velemínský
mesh_terms: D001205:Ascorbic Acid / Q000494:pharmacology; D055598:Chemical Phenomena; D002621:Chemistry; D006812:Humic Substances; D008770:Methylnitrosourea; D009152:Mutagenicity Tests; D009154:Mutation / Q000187:drug effects*; D009573:Nitrites; D010944:Plants
chemical_list: D006812:Humic Substances; D009573:Nitrites; D008770:Methylnitrosourea; D001205:Ascorbic Acid