Mutagenicity of the reaction products of dibenzo-p-dioxin with nitrogen oxides.

Dibenzo-p-dioxin (DD) was made to react with various concentrations of nitrogen oxides in the dark. The mutagenicities of the reaction products were tested using Salmonella typhimurium strains TA98, TA100, TA98NR and TA98/1,8-DNP6 in the presence or absence of a mammalian metabolic activation system (S9 mix). DD-NOx (molar ratios 1:3, 1:6 and 1:18) reaction products exhibited mutagenic potency in strains TA98 and TA98/1,8-DNP6 without S9 mix. In a gas chromatography/mass spectrometry study, 2-nitrodibenzo-p-dioxin (NDD) was identified with authentic sample in the mutagenic reaction products. DD-NOx (1:18) reaction products were reduced by sodium hydrogen sulfide and the reduction mixture was analyzed by HPLC. 2,7-Dinitrodibenzo-p-dioxin (DNDD) and 2,8-DNDD were identified as corresponding diamino-DDs in the reduction mixture. 2-NDD, 2,7-DNDD and 2,8-DNDD were also mutagenic in strains TA98 and TA98/1,8-DNP6 without S9 mix and the mutagenicity of DD-NOx reaction products was largely accounted for by the nitro-DDs.     

Mutagenicity of smoked, dried bonito products

Mutagens have been found in smoked, dried bonito products, popular items in Japanese foods. The mutagens were isolated by means of blue cotton, an absorbent cotton preparation with covalently bound trisulfo-copper-phthalocyanine residues, and by means of XAD-2 resin. The mutagenicity was positive in Salmonella typhimurium strain TA98 with metabolic activation. The mutagens are produced during the process of smoking-and-drying bonito (a process called baikan). The activity was much higher than that expected from the content of benzo[a]pyrene. In contrast to benzo[a]pyrene, the mutagens were not inhibited by ellagic acid. The mutagenicity was not abolished by treatment with nitrite. Thin-layer and high-performance liquid chromatographic analysis gave two mutagenic fractions, both of which were distinguishable from benzo[a]pyrene and from the pyrolysis products Trp-P-1, Trp-P-2, Glu-P-1, Glu-P-2, A alpha C and MeA alpha C. The major mutagenic component was not chromatographically distinguishable from IQ and MeIQx, and the minor one was very similar to MeIQ. The smoked, dried bonito products contained free fatty acids, which were inhibitory to the mutagenicity of the bonito products.     

Mutagenicity of amine drugs and their products of nitrosation

Mouse spot tests using dimethylbenz[a]anthracene (DMBA) were carried out on PW strain male mice and female C57BL/6 mice. DMBA induced somatic gene mutations in developing mouse embryonic cells. Pretreatment of pregnant females with phenobarbital (PB) reduced the incidence of somatic mutation by DMBA. The testes of males treated with DMBA in utero, whether treated with PB or not, showed severe retardation of development. The amount of cytochrome p-450 in the liver of C57BL/6 females increased about 2-fold by the pretreatment schedule, carried out on days 10-12 of pregnancy.     

New potent antioxidative o-dihydroxyisoflavones in fermented Japanese soybean products.

A potent antioxidative 6-hydroxydaidzein (6-OHD) was newly isolated from soybean koji fermented with Aspergillus oryzae. 6-OHD, in addition to 8-hydroxydaidzein and 8-hydroxygenistein, were found to be present in various fermented soybean products, including their koji. Considering that these o-dihydroxyisoflavones had strong antioxidative activities, they may contribute to protecting from oxidative deterioration during the processing of fermented soybean products.     

Mutagenicity of products formed by ozonation of naphthoresorcinol in aqueous solutions

The mutagenicity of products formed by ozonation of naphthoresorcinol in aqueous solution was assayed with Salmonella typhimurium strains TA97, TA98, TA100, TA102 and TA104 in the presence and absence of S9 mix from phenobarbital- and 5,6-benzoflavone-induced rat liver. Ozonated naphthoresorcinol was mutagenic in TA97, TA98, TA100 and TA104 without S9 mix. By the addition of S9 mix, the mutagenic activity of ozonated naphthoresorcinol was markedly suppressed in TA98 and TA100, but became positive in TA102. High-performance liquid chromatography (HPLC) after derivatization to 2,4-dinitrophenylhydrazones demonstrated the formation of glyoxal as an ozonation product of naphthoresorcinol. Ion chromatographic technique also demonstrated the formation of o-phthalic acid, muconic acid, maleic acid, mesoxalic acid, glyoxylic acid and oxalic acid as ozonation products. The mutagenicity assays of these identified products with five Salmonella showed that glyoxal and glyoxylic acid were directly mutagenic; the former in TA100, TA102 and TA104, the latter in TA97, TA100 and TA104. In the presence of S9 mix, glyoxylic acid gave a positive response of mutagenicity for TA102. The experimental evidence supported that glyoxal and glyoxylic acid may contribute to the mutagenicity of ozonated naphthoresorcinol.     

Mass spectral studies of probe pyrolysis products of intact oligoribonucleotides.

Pyrolysis of underivatized homogeneous oligoribonucleotides in the source of a mass spectrometer leads to production of simple mass spectra which resemble the spectra of the bases themselves. It is proposed that pyrolysis occurs by hydrogen transfer to the base moiety followed by elimination of the neutral base. Ionization by electron impact gives rise to the observed spectra. Mixed oligoribonucleotides pyrolyze readily to give spectra of adenine and uracil, but evidence for the presence of guanine and cytosine in mixed polymers and native RNA's is difficult to obtain presumably because of their low vapor pressure. The method may be useful for detection of modified bases in tRNA and for studies of temperature effects on RNA pyrolysis.     

Multiple vacuolar sorting determinants exist in soybean 11S globulin

The sorting determinants of glycinin, a soybean (Glycine max) 11S globulin, which mediates protein targeting to the protein storage vacuole (PSV), were investigated in maturing soybean cotyledons by transient expression assays. A C-terminal stretch of 10 amino acids of A1aB1b, a glycinin group I subunit, was sufficient to direct green fluorescent protein (GFP) to the PSV. This peptide may correspond to a C-terminal vacuolar sorting determinant (ctVSD). Because functional inhibition of this putative ctVSD of A1aB1b did not block PSV sorting of A1aB1b, we used the three-dimensional structure of A1aB1b to identify candidates for a sequence-specific determinant (ssVSD). We found that the sequence downstream of disordered region 4 could direct GFP to the PSV and that Ile-297 is critical for sorting. However, functional inhibition of the ctVSD, combined with the Ile297Gly mutation, did not abolish the vacuolar sorting of A1aB1b, suggesting that A1aB1b has a third sorting determinant in addition to ctVSD and ssVSD. A glycinin group II subunit, A3B4, lacked a ctVSD but contained a VSD reminiscent of an ssVSD and an additional sorting determinant. We also demonstrate, by expression of dominant negative mutants of small GTPases and drug treatment experiments, that the trafficking of A1aB1b is COPII vesicle-dependent and wortmannin- and brefeldin A-sensitive.     

Mutagenicity on chlorination of products formed by ozonation of naphthoresorcinol in water

The mutagenicity of products formed by chlorination after ozonation of naphthoresorcinol in aqueous solution was assayed with Salmonella typhimurium strains TA98 and TA100 in the presence and absence of S9 mix from phenobarbital- and 5,6-benzoflavone-induced rat liver. Ozonated and subsequently chlorinated naphthoresorcinol was directly mutagenic, as was ozonated naphthoresorcinol, in both strains tested. The mutagenic activity at chlorination with 8 equivalents of chlorine per mole of naphthoresorcinol after ozonation was markedly higher than that at only ozonation. Of the identified ozonation products of naphthoresorcinol, muconic acid, after chlorination with 2 or 4 equivalents of chlorine per mole of the compound, induced direct mutagenicity against TA98 and TA100. The chlorination of glyoxal with 0.5 and 1 chlorine equivalents per mole of the compound was shown to produce direct mutagenicity toward TA98. The identification of the chlorination products of these compounds is also discussed.     

Mutagenicity of methylisocyanate and its reaction products to cultured mammalian cells

Methylisocyanate (MIC) induced mutagenic responses in the absence of exogenous activation in the mouse lymphoma cell forward mutation assay at concentrations as low as 8-24 microM. MIC produced predominantly small mutant colonies, suggesting the possibility of clastogenic activity. The intermediate hydrolysis product, methylamine, was also mutagenic without exogenous activation but required several hundred-fold higher concentrations (ca. 3 mM). N,N'-Dimethylurea, the final product in the reaction of methylisocyanate and water, was totally refractory in either the presence or absence of S9 for concentrations up to 57 mM (5 mg/ml). The ethyl ester of N-methylcarbamic acid was also tested since it was the only available analogue to the highly reactive N-methylcarbamic acid intermediate. This compound was mutagenic only in the presence of S9 at doses exceeding 5-40 microM, which suggested the possibility that the free acid, produced by enzymatic hydrolysis, is also mutagenic. The mutagenic activity of the ester resulted solely in the production of small mutant colonies.     

Liquid hydrocarbon fuels obtained by the pyrolysis of soybean oils

The pyrolysis reactions of soybean oils have been studied. The pyrolytic products were analyzed by GC–MS and FTIR and show the formation of olefins, paraffins, carboxylic acids and aldehydes. Several kinds of catalysts were compared. It was found that the amounts of carboxylic acids and aldehydes were significantly decreased by using base catalysts such as Na₂CO₃ and K₂CO₃. The low acid value pyrolytic products showed good cold flow properties and good solubility in diesel oil at low temperature. The results presented in this work have shown that the pyrolysis of soybean oils generates fuels that have chemical composition similar to petroleum based fuels.     

Fast pyrolysis of soybean cake: product yields and compositions

This study was an investigation of the role of important parameters influencing pyrolysis yields from soybean cake. Experiments were carried out at temperatures ranging from 400 to 700 degrees C, for various nitrogen flow rates, heating rates and particle sizes. The maximum liquid yield was 42.83% at a pyrolysis temperature of 550 degrees C with a sweeping gas rate of 200 cm3 min(-1) and heating rate of 700 degrees C min(-1) for a soybean cake sample having 0.425 < D(p) < 0.85 mm particle size. The various characteristics of liquid product were identified. Thus, the aliphatic sub-fraction of the bio-oil was analysed by GC-MS and further structural analyses of bio-oil and aromatic and polar sub-fractions were conducted using FT-IR and 1H-NMR. The H/C ratios and the structural analysis of the fractions obtained from the biocrudes showed that the fractions were quite similar to currently utilised transport fuels.     

Mutagenicity studies with nitrofurans. I. Mutagenicity of nitrofurylacrylic acid for mammals

Cytogenetic analysis of mouse bone-marrow cells, the dominant lethal test in mice and the cytogenetic analysis of human peripheral lymphocytes in vitro were used to study the mutagenicity of 3-(5-nitro-2-furyl)acrylic acid (5-NFA) for mammals. The bone-marrow cytogenetic analysis was performed in female mice exposed to 5-NFA administered intraperitoneally in single doses of 15--120 mg/kg and in 5 repeated doses of 15 and 30 mg/kg, intragastrically in single doses of 30--240 mg/kg and 5 repeated doses of 30 and 60 mg/kg, and perorally for 12 weeks to 5-NFA concentration of 10, 100 and 1000 mg 5-FNA/1 in drinking water. The bone-marrow analysis was performed in this case after 12 days, 3, 4, 6, 8, 10 and 12 weeks exposure. No increase in chromosome damage attributable to dosing with 5-NFA occurred in any of these experiments. Experiments in which mice were exposed to 5-NFA in drinking water for 12 weeks and then treated with a single i.p. dose of 2 mg of the mutagen TEPA [trix-(1-aziridinyl)phosphine oxide] per kg revealed that, at a concentration of 1000 mg 5-NFA/1, the clastogenic activity of TEPA was reduced to that in untreated animals. The dominant lethal test was performed in male mice exposed to 5-NFA applied intraperitoneally in single doses of 40--120 mg/kg and in 5 repeated doses of 10--30 mg/kg, intragastrically in 5 repeated doses of 20--60 mg/kg, and perorally for 4 weeks in drinking water containing 5-NFA at concentrations of 10, 100, 316 and 1000 mg/l. No significant differences were detected between the exposed and control groups of animals. Experiments in which male mice were exposed to 5-NFA in drinking water and treated after the 4-week exposure to 5-NFA with 1 mg TEPA/kg revealed that a concentration of 1000 mg 5-NFA/1 reduced TEPA-induced dominant lethality to within control values. A reduction in male fertility was observed after the single or repeated 5-NFA doses, but no changes when 5-NFA was applied in drinking water. The cytogenetic analysis of human peripheral lymphocytes exposed in vitro for the last 24 h of culture to concentrations of 1--100 micrograms 5-NFA/Ml did not show any compound-related chromosomal changes. The results of dominant-lethal and bone-marrow cytogenetic studies in mice after consumption of drinking water containing 1000 mg of 5-NFA/1 for 12 weeks and dosed subsequently with TEPA suggests that 5-NFA has some antimutagenic activity. Because none of the studies reported revealed any compound-related genetic activity, the results suggest that 5-NFA is not a chromosome-breaking agent in mammals.