Motoshi Nohara

The effect of quercetin on the mutagenicity of 2-acetylaminofluorene and benzo[a]pyrene in Salmonella typhimurium strains

The comutagenic and desmutagenic effect of quercetin on the mutagenicity of typical mutagens e.g. 2-acetylaminofluorene (AAF), 4-nitroquinoline-1-oxide (4NQO) and benzo[alpha]pyrene (B[a]P), in Salmonella typhimurium TA98, TA100 and TA98/1,8 DNP6 were examined. In the mixed application of AAF with quercetin in the presence of mammalian metabolic activation system (S9 mix), the numbers of revertants in TA98 increased by as much 2.2-5.0-fold compared with the sum of those in the separate applications of AAF and quercetin. A 1.4-2.7-fold increase was observed in TA100. Quercetin did not affect the mutagenicity of 4NQO, and depressed that of B[a]P. Dose-response curves for mutagenicity of quercetin with or without AAF (5 micrograms/plate) were examined. The results suggest that quercetin, present in a molarity of up to 1.5 times that of AAF, is apparently effective in enhancing the mutagenicity of AAF, because a linear dose-response curve was observed in the range of 0-5 micrograms/plate quercetin with AAF although quercetin alone was not mutagenic in the same range. Dose-response curves for mutagenicity of quercetin with or without 5 micrograms/plate B[a]P did not increase compared with that for quercetin alone. The mutagenicity of the mixed application of B[a]P with quercetin was reduced to about 60% of the sum of separate application at doses ranging from 25 to 100 micrograms/plate of quercetin. Since enhancement and depression of mutagenicity by quercetin were observed for indirect mutagens, AAF and B[a]P, respectively, in the presence of S9 mix, quercetin may affect the metabolic pathway of these mutagens.

Determination of arsenite, arsenate and monomethylarsonic acid in aqueous samples by gas chromatography of their 2,3-dimercaptopropanol (bal) complexes

Procedures are described for the determination of arsenite, arsenate and monomethylarsonic acid in aqueous samples. The arsenicals (after reduction of arsenic to the tervalent state) readily react with 2,3-dimercaptopropanol (BAL) to yield their BAL complexes. The products are extracted with benzene and introduced into a gas Chromatograph equipped with a flame-photometric detector for sulphur. One aliquot of sample is treated with stannous chloride solution and potassium iodide solution to reduce arsenate and monomethylarsonic acid, then BAL is added and the complexes are extracted with benzene. The extract is analysed for total inorganic As plus monomethylarsonic acid. Magnesia mixture and phosphate solution are added to another aliquot to remove arsenate by co-precipitation with magnesium ammonium phosphate. The precipitate is filtered off and arsenite determined in the filtrate. The detection limits are 0.02 ng of As for arsenate and arsenite and 0.04 ng of As for monomethylarsonic acid.

Gas chromatographic determination of dimethylarsinic acid in aqueous samples.

Procedures are described for the determination of dimethylarsinic acid in aqueous samples by gas chromatography of iododimethylarsine. Dimethylarsinic acid is converted into iododimethylarsine rapidly and quantitatively by treatment with hypophosphorous acid and potassium iodide, the resulting iododimethylarsine is extracted with toluene and determined with a gas chromatograph equipped with an electron-capture detector. The detection limit is 0.005 ppm as As. Recoveries from urine are over 95%. Other arsenicals do not give any response in the chromatography. The method has been applied to the determination of dimethylarsinic acid in urine and in water extracts of sea-weeds.

High-performance liquid chromatographic determination of N1-alkylnicotinamide in urine.

A simple high-performance liquid chromatographic method has been developed for determining N1-alkylnicotinamides, including C1-C5 alkyl derivatives, in urine. N1-Alkylnicotinamides were reacted with acetophenone in strong alkali medium at 0 degrees C and then formic acid was added. The reaction mixture was heated in acidic medium at above 93 degrees C, and the fluorescent product, 1-alkyl-7-phenyl-1,5-dihydro-5-oxo-1,6-naphthyridine, was chromatographed by HPLC, using a Zorbax SCX-300 column with a mixed mobile phase of acetonitrile-0.04 M ammonium phosphate, monobasic. N1-Alkylnicotinamides can be determined as 1,6-naphthyridine derivatives by a fluorometric detector at a level of 100 pg (signal/noise = 2). Recoveries of N1-alkylnicotinamides in urine were satisfactory. Interfering reaction products from NAD+ and NADP+ were clearly eliminated for determination of N1-alkylnicotinamides without pentyl derivatives.

Mutagenicity of coal-pyrolyzed products and their photochemical reaction products with nitrogen oxides in Salmonella typhimurium TA98 and TA100

The chemical class separation of coal-pyrolyzed products and the photochemical reaction of these fractions with nitrogen oxides in the experimental chamber, and the application of a short-term mutagenicity test were investigated. The altered products from the fraction hydroxy polycyclic aromatic compounds in a simulated atmosphere containing a small volume of nitrogen oxides under irradiation with a xenon lamp were the most potent mutagenic fraction among all the fractions tested against Salmonella typhimurium, both TA98 and TA100, with or without S9.