Mutagenic activity of organic esters are likely to form from bromo-2 ethanol generated during fumigation using ethylene oxide

The mutagenic potencies of 13 bromoethyl esters of natural organic acids, have been studied, by Ames's test (strains TA 98 and TA 100, with and without system of metabolisation, S9 mix). None of the 8 bromoethyl esters of linoleic, oleic, palmitic, stearic, lauric, myristic, cinnamic and fumaric acids is genotoxic. On the other hand the 5 others derived from gallic, oxalic, tartric acids (strain TA 100 with and without S9 mix), malic and citric acids (strain TA 100 with S9 mix) are mutagenic, the ester of gallic acid giving still a doubtful mutagenic response; their mutagenic potencies are 2 to 3 times smaller than that of bromo-2 ethanol. This observation, complemently with the mutagenicity of some organic esters of the chloro-2 ethanol, proves the potential danger of ethylene oxide used for the fumigation of foods or vegetables and medicinal plants containing much chloride and/or bromide.     

共轭亚油酸构效关系及其分子药理研究进展

共轭亚油酸是一系列异构体的总称，其中具有多种生物功能的异构体主要是c9，t11-共轭亚油酸和t10，c12-共轭亚油酸。本文简要阐述了共轭亚油酸活性异构体的分布和来源，并重点综述了c9，t11-共轭亚油酸和t10，c12-共轭亚油酸这两种异构体对动物体内脂肪、脂类代谢和癌症的影响差异，从构效关系上分析了它们的药理作用机制。     

Lipid microencapsulation in starch

Short microwave heating of granular potato, waxy corn and tapioca starches with such lipids as cis-9-octadecenoic acid (oleic acid), cis,cis-9,12-octadecadienoic acid (linoleic acid), octadecanoic acid (stearic acid), ethyl cis-9-octadecenoate, ethyl cis,cis-9,12-octadecadienoate and methyl octadecanoate provided microcapsules in which encapsulated guest molecules did not interact with starch microcapsules. On the formation of microcapsules, the lipid guest molecules did not react to starches. The encapsulation yield varied between almost 11-94%.     

Monohydroxylation and esterification as determinants of the effects of cis- and trans-9-octadecenoic acids on the permeation of hydrocortisone and 5-fluorouracil across hairless mouse skin in vitro

The effects of cis-9-octadecenoic acid (oleic acid) and of a group of chemically related cis- (ricinoleic acid) and trans- (ricinelaidic acid) 12-monohydroxylated derivatives and their corresponding ethyl and methyl esters on the skin permeation of model hydrophobic (hydrocortisone, log K=1.61) and hydrophilic (5-fluorouracil, log K=-0.89) drugs was investigated in vitro using excised hairless mouse skin. Drug solutions were prepared in propylene glycol, with and without the addition of a fatty acid to a level of 5%. Whereas the addition of oleic acid markedly enhanced the transdermal flux of both drugs relative to a sample in propylene glycol alone (hydrocortisone approximately 1800-fold; 5-fluorouracil approximately 330-fold), that of a cis- or trans-12-monohydroxylated analog of oleic acid resulted in only a small increase (1.4-2.7-fold for hydrocortisone; 4.4-6.6-fold for 5-fluorouracil). On the other hand, the methyl and ethyl esters of cis- and trans-12-hydroxy-9-octadecenoic acid exerted a much greater enhancing effect (327-720-fold for hydrocortisone, 42-74-fold for 5-fluorouracil) than the corresponding parent fatty acids. Furthermore, whereas the ethyl esters were found to have a greater effect on the skin permeation of hydrocortisone than the methyl esters, the reverse was true with regards to 5-fluorouracil. Additionally, the esters of trans-12-hydroxy-9-octadecenoic acid promoted permeation to an extent comparable to that achieved with their cis-counterparts.     

Mutagenicity tests of lipid oxidation products in Salmonella typhimurium: Monohydroperoxides and secondary oxidation products of methyl linoleate and methyl linolenate

Nine hydroperoxy and hydroperoxy-epidioxy oxidation products derived from either autoxidation (AO) or photosensitized oxidation (PO) of methyl linoleate (MLo) or methyl linolenate (MLn) were tested for mutagenic activity by the Salmonella typhimurium his⁺ reversion assay using strains TA100, TA98, TA102, TA97 and TA1537. All nine oxidation products, monohydroperoxides from AO-MLn (I) or from PO-MLn (II), dihydroperoxides from PO-MLo (III), AO-MLn (IV) or PO-MLn (V), hydroperoxy epidioxides from PO-MLo (VI), AO-MLn (VII) or PO-MLn (VIII) and hydroperoxy bis-epidioxides from PO-MLn (IX), were weakly mutagenic in strains TA97 and/or TA100. The hydroperoxy epidioxides (VI–IX) exhibited significantly greater activity in strain TA97 than did the monohydroperoxides (I, II) or the dihydroperoxides (III–V). In strain TA100, all of the oxidation products tested exhibited similar activity. No major differences between products derived from autoxidized and photooxidized MLn (I v. II, IV v. V, VII v. VIII) were obtained. Rat-liver S-9 reduced the toxicity of all oxidation products to the tester strains. The greatest mutant yields were usually obtained in the presence of S-9, but mutagenic potency was sometimes greater without S-9. The structural feature common to all of the mutagenic oxidation products was the presence of a hydroperoxy group, suggesting that this characteristic is responsible for the observed mutagenicity, either directly or through a common degradative pathway to reactive products of lower molecular weight.     

Synthesis,characterization and mutagenicity of new cis-[Pt(2-substituted-benzimidazole)2Cl2] complexes

In this study, four new platinum(II) complexes with the structures cis-[Pt(Ligand)2Cl2] (ligand = 2-(p-methoxy-/or-p-chlorobenzyl or p-methoxyphenyl)benzimidazol (1, 2, 4 respectively) and 5(6)-methyl-2-phenoxymethylbenzimidazole (3) were synthesized and characterized by their elemental analysis, and IR and 1H NMR spectra. The potentials of the Pt(II) complexes for short-term bacterial mutagenicity were tested in reverse-mutation assays using Salmonella typhimurium frame-shift strain T 98 and S. typhimurium TA 100 and TA 102 strains, which carry mutations particularly sensitive to reversion by DNA base-pair substitution. The tests were performed in the absence of S9 rat liver fraction. Among the complexes tested 1 had no mutagenic activity. Complex 4 was found to be weakly mutagenic in TA 98 only. The Pt(II) complexes 2 and 3 were found to be mutagenic in TA 98, TA 100 and TA 102.     

Defining mechanisms of toxicity for linoleic acid monoepoxides and diols in Sf-21 cells

Linoleic acid monoepoxides have been correlated with many pathological conditions. Studies using insect cells derived from Spodoptera frugiperda (Sf-21 cells) have suggested that conversion of the epoxides to the diols is required for toxicity. However, more recent studies using rabbit renal proximal tubules have suggested that linoleic acid monoepoxides are direct mitochondrial toxins. To better understand these discrepancies, we compared the toxicity of these linoleic acid metabolites in Sf-21 cells using mitochondrial respiration as an end point. Linoleic acid (100 microM) and 12,13-epoxy-9-octadecenoic acid (12,13-EOA, 100 microM) increased the rate of oligomycin-insensitive respiration by approximately 3.5- and 3-fold, respectively, decreased the rate of oligomycin-sensitive respiration by approximately 52 and 68%, respectively, and had no effect on the integrity of the electron transport chain. These effects were concentration-dependent, occurred within 1 min, and recovered to basal levels within 45 min. 12,13-Dihydroxy-9-octadecenoic acid (12,13-DHOA, 100 microM) had no effect on oligomycin-insensitive respiration but decreased the rate of oligomycin-sensitive respiration and uncoupled respiration in a concentration-dependent manner. Approximately 79 and 68% of oligomycin-sensitive respiration and uncoupled respiration was inhibited by 12,13-DHOA (100 microM), respectively. These effects occurred within 1 min and were not reversible in 6 h. Effects similar to those induced by 12,13-DHOA (100 microM) were observed using 12,13-EOA (100 microM) in Sf-21 cells expressing human soluble epoxide hydrolase. These data suggest that in this Sf-21 model linoleic acid and linoleic monoepoxides have transient uncoupling effects, whereas the primary mechanism of toxicity for linoleic acid diols in this model is inhibition of the electron transport chain.     

Analysis of the toxic effects of linoleic acid, 12,13-cis-epoxyoctadecenoic acid, and 12,13-dihydroxyoctadecenoic acid in rabbit renal cortical mitochondria

P450 epoxidation of linoleic acid has been associated with many pathological conditions that often lead to acute renal failure. However, there is only suggestive evidence that linoleic acid monoepoxides and/or linoleic diols directly induce mitochondrial dysfunction. Using isolated rabbit renal cortical mitochondria (RCM), we found that linoleic acid (50 microM) and the linoleic acid monoepoxide, cis-12,13-epoxy-9-octadecenoic acid (12,13-EOA, 50 microM) increased state 4 and oligomycin-insensitive respiration and reduced state 3 and oligomycin-sensitive respiration. Concomitant with these effects, linoleic acid and 12,13-EOA decreased mitochondrial membrane potential (DeltaPsi). In contrast, the hydrolyzed product of 12,13-EOA, 12,13-dihydroxyoctadecenoic acid (12,13-DHOA, 50 microM), had no effect on state 3, state 4, oligomycin-sensitive, and oligomycin-insensitive respiration, and DeltaPsi. Neither linoleic acid or its metabolites altered uncoupled respiration, which suggests that these compounds have no affect on electron transport chain in RCM. Nucleotides such as ATP (0.5 mM) and GDP (0.5 mM) partially prevented the decrease in DeltaPsi but did not attenuate the increase in oligomycin-insensitive respiration after exposure to linoleic acid (50 microM) and 12,13-EOA (50 microM). These results demonstrate that linoleic acid metabolism to the 12,13-DHOA is a detoxification pathway that prevents mitochondrial dysfunction in RCM. The increase in state 4 respiration concomitant with decreases in state 3 respiration and DeltaPsi suggest that, in addition to uncoupling effects, linoleic acid and 12,13-EOA may have other effects, such as alterations of mitochondrial membranes. The inability of ATP and GDP to fully attenuate the uncoupling effects of linoleic acid and 12,13-EOA suggests that these effects are mediated through a nucleotide-independent mechanism.     

Lipid microencapsulation in starch

Short microwave heating of granular potato, waxy corn and tapioca starches with such lipids as cis-9-octadecenoic acid (oleic acid), cis,cis-9,12-octadecadienoic acid (linoleic acid), octadecanoic acid (stearic acid), ethyl cis-9-octadecenoate, ethyl cis,cis-9,12-octadecadienoate and methyl octadecanoate provided microcapsules in which encapsulated guest molecules did not interact with starch microcapsules. On the formation of microcapsules, the lipid guest molecules did not react to starches. The encapsulation yield varied between almost 11–94%.     

A reactive metabolite of furan, cis-2-butene-1,4-dial, is mutagenic in the Ames assay

Furan is classified as a nongenotoxic hepatocarcinogen. It is thought to be activated to a toxic metabolite, cis-2-butene-1,4-dial, which is acutely toxic to liver cells. The resulting cytotoxicity is followed by compensatory cell proliferation, increasing the likelihood of tumor production. We examined the genotoxic activity of cis-2-butene-1,4-dial in several strains of Salmonella typhimurium commonly used in the Ames assay. This reactive compound tested positive in TA104, a strain that is sensitive to aldehydes. Mutagenic activity was concentration-dependent (1000 +/- 180 revertants/micromol). Incubation of cis-2-butene-1,4-dial with glutathione prior to addition of bacteria inhibited both the acute toxic and genotoxic activity of this compound. No evidence of mutagenic activity was seen at nontoxic concentrations in TA97, TA98, TA100, and TA102. Our findings are consistent with the hypothesis that cis-2-butene-1,4-dial reacts with DNA to form mutagenic adducts. Our data suggest that cis-2-butene-1,4-dial may be an important genotoxic as well as toxic intermediate in furan-induced tumorigenesis.     

Ames mutagenicity tests on purified 3-nitropropionic acid

3- Nitropropionic acid is a toxic compound produced by several moulds involved in food fermentation or spoilage. An impure commercial sample of this compound was previously reported as being mutagenic to Salmonella typhimurium strains TA1535 and TA100. In the present study, a sample from the same lot of 3- nitropropionic acid was mutagenic in strain TA100 without metabolic activation, but this activity was diminished after recrystallization. This sample was not mutagenic in strain TA98, before or after recrystallization. A new, purer commercial sample was non-mutagenic in strains TA98, TA100 and TA1538, with or without metabolic activation. Therefore the mutagenicity reported to be due to 3- nitropropionic acid was considered to be due to the impurity(ies).     

Conjugated linoleic acid and the control of cancer and obesity

The effects of conjugated linoleic acid (CLA) in animals are reviewed. In most of the CLA preparations that have been investigated to date for biological activity, two CLA isomers are present in about equal concentrations: cis-9,trans-11 CLA, and trans-10,cis-12 CLA. The occurrence of these isomers in foods and their production by rumen microorganisms are discussed. Potential mechanisms of action as regards the effects of CLA on cancer and body composition are reviewed, including recent evidence that body composition changes are produced by the trans-10,cis-12 CLA isomer. Evidence is presented indicating that CLA may modulate cellular response to tumor necrosis factor-alpha (TNF- alpha). The mechanistic implications of this finding are considered.      

Mutagenicity assay in Salmonella for thirteen 2-substituted-1 H-phenanthro (9,10-d) imidazoles

Some 2-substituted-1 H-phenanthro [9,10-d] imidazole compounds synthesized as a predrugs were tested in mutagenicity assays in Salmonella strains TA97, TA98, and TA100 using a plate incorporation assay both with and without S9 mix. The 10 substances were mutagenic in TA97 and five of them were mutagenic only with metabolic activation, whereas one of them did not require the addition of S9. The eight substances were mutagenic in TA98 only with S9. For TA100, seven substances showed positive results both with and without S9, however another four required S9, whereas only one of them did not required metabolic activation. In summary, all of 13 substances derived from phenanthro [9,10-d] imidazole were found to be mutagenic for at least one or two of the three strains and their mutagenicity are discussed.     

Mutagenicity testing of agent orange components and related chemicals

Components of the herbicide Agent Orange--2,4-dichlorophenoxyacetic acid (2,4,-D) and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) and their esters, and the contaminant 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)--and related chemicals were tested for mutagenicity using Salmonella typhimurium strains TA98, TA100, TA1535, and TA1537. No mutagenic activity was observed for any of the chemicals tested.     

Mutagenic activity promoted by amentoflavone and methanolic extract of Byrsonima crassa Niedenzu

Byrsonima crassa is a plant pertaining to the Brazilian central savannah-like belt of vegetation and popularly used for the treatment of gastric dysfunctions and diarrhoea. The methanol extract contains catechin, tannins, terpenes and flavonoids; both mutagenic potential and antioxidant properties have been ascribed to flavonoids. The mutagenicity of some flavonoids is believed to be associated with the formation of reactive oxygen species and seems to depend on the number and position of hydroxyl groups. In the present study the mutagenic activity of the methanol, chloroform and 80% aqueous methanol extracts, as well as acetate and aqueous sub-fractions, of this medicinal plant were evaluated by Salmonella typhimurium assay, using strains TA100, TA98, TA102 and TA97a, and in mouse reticulocytes. The results showed mutagenic activity of the methanolic extract in the TA98 strain without S9, but no mutagenicity to mouse cells in any of the extracts. The acetate fraction showed strong signs of mutagenicity without S9, suggesting that in this enriched fraction were concentrated the compounds that induced mutagenic activity. The aqueous fraction showed no mutagenic activity. The TLC and HSCCC analyses of the acetate fraction with some standard compounds permitted the isolation of the quercetin-3-O-beta-D-galactopyranoside, quercetin-3-O-alpha-L-arabinopyranoside, amentoflavone, methyl gallate and (+)-catechin, of which only the amentoflavone exhibited positive mutagenicity to TA98 (+S9, -S9).     

Mutagenicity Assay in Salmonella for Thirteen 2-Substituted-1H-phenanthro (9,10-d) Imidazoles

Abstract

Some 2-substituted-1H-phenanthro [9,10-d] imidazole compounds synthesized as a predrugs were tested in mutagenicity assays in Salmonella strains TA97, TA98, and TA100 using a plate incorporation assay both with and without S9 mix. The 10 substances were mutagenic in TA97 and five of them were mutagenic only with metabolic activation, whereas one of them did not require the addition of S9. The eight substances were mutagenic in TA98 only with S9. For TA100, seven substances showed positive results both with and without S9, however another four required S9, whereas only one of them did not required metabolic activation. In summary, all of 13 substances derived from phenanthro [9,10-d] imidazole were found to be mutagenic for at least one or two of the three strains and their mutagenicity are discussed.     

Mutagenic activity of the condensates from thermal decomposition of different polyamides]

The mutagenic activity of the condensates from oxydative pyrolysis of various polyamides at 500, 800 and 1,000 degrees C has been searched for by AMES preincubation test in strains TA 98 and TA 100 with or without metabolic activation by an Aroclor 1254 induced rat liver microsomal S9mix fraction. All condensates are mutagenic in the presence of this fraction and most of them are far less or not mutagenic in the absence of S9mix. Strain TA 98 is more sensitive than strain TA 100 for detecting the mutagenic activity of these condensates. So, they mainly contain indirect mutagenic substances responsible for frameshift mutation. In all cases, mutagenic activity is maximum at 800 degrees C. This observation should draw the attention upon the genotoxic (carcinogenic) long term risk induced by thermal decomposition of plastics and then upon the necessary protection of firemen and others in charge of domestic or hospital solid waste incineration.     

In vitro mutagenicity of rubber chemicals and their nitrosation products

14 chemicals employed in rubber manufacture were assayed in the Salmonella reversion test with the strains TA98 and TA100. Mixed diaryl-p-phenylenediamines were weakly mutagenic in TA98 after metabolic activation; poly-p-dinitrosobenzene was active in TA98 without as well as with S9. After in vitro reaction with nitrite at low pH, mixed diaryl-p-phenylenediamines became directly mutagenic in both strains, whereas poly-p-dinitrosobenzene retained its activity unchanged. Furthermore, 4 of the remaining chemicals acquired mutagenic characteristics: in the presence of S9, N,N'-dimethylpentyl-p-phenylenediamine reverted TA98 and hexamethylenetetramine reverted both TA98 and TA100; N-isopropyl-N'-phenyl-p-phenylenediamine was mutagenic in TA98 with and without S9; N-nitrosodiphenylamine was active in both strains without S9 and weakly mutagenic in TA98 after metabolic conversion.     

Lack of release from hepatocytes in vitro or excretion in vivo of mutagenic chrysoidine metabolites

Rat liver postmitochondrial supernatant (S9) converted the azo dyes chrysoidine Y and R to products that were mutagenic towards Salmonella typhimurium strain TA100. No such release of mutagens was demonstrated using intact rat hepatocytes as an activation system despite the fact that chrysoidine dyes cause unscheduled DNA synthesis in these cells. It appears that genotoxic products produced within hepatocytes either react within the cell or are detoxified prior to release. Following intraperitoneal administration of chrysoidine Y to rats (100 mg/kg i.p.) there was also no evidence of mutagenic or por-mutagenic products excreted in bile or urine. The S9-derived mutagens appear to be largely independent of bacterial acetylation since they were active in the acetylation-deficient strain TA98/1,8-DNP6 in addition to strain TA98. The ultimate mutagenic form(s) are therefore unlikely to be acetoxyarylamines.     

Screening of tabacco smoke constituents for mutagenicity using the Ames' test

To clarify the mutagenic activity of individual smoke components, 239 compounds, representative of the gaseous and semivolatile phases of tobacco smoke, were assayed for mutagenicity towards 4 histidine-requiring mutants of Salmonella typhimurium (TA 98, TA 100, TA 1535 and TA 1537). All compounds were tested qualitatively both with and without metabolic activation using a liver fraction (S-9) from Aroclor 1254 or methylcholanthrene induced rats. Without S-9, only 2,3-dimethylindole and 2,3,5-trimethylindole showed mutagenic activity that was not enhanced by hte metabolic activation system. 2,6-Diaminotoluene and coronene, which like the above compounds are not documented carcinogens were found to be mutagenic for strain TA 98 with S-9. Mutagenic activity was also observed for the previously known mutagens benz[a]pyrene, chrysene, benz[a]-anthracene, perylene and β-naphthylamine, on exposure to strains TA 98 and/or TA 100 with S-9.