Mutagenic activity extracts

The mutagenic activity of the extracts was assayed using Salmonella typhimurium strain TA 1535, as described by McCann et al. (58). Ten ul of fish extract were spot-tested without addition of an S9-enzyme preparation (57). MNNG (20 ug/plate) was used as a positive control. 

G.A. Umbuzeiro, D.A. Roubicek, C.M. Rech, M.I.Z. Sato and L.D. Claxton, Investigating the sources of the mutagenic activity found in a river using the Salmonella assay and different water extraction procedures. Chemosphere, 54 (2004) 1589-1597. 

Mutagenic activity. Petroleum ether extract of the aerial parts, in the ration of Drosophila at concentrations of 0.5, 1, and 5% of the diet, was active . Petroleum ether extract of the dried leaf, administered by gastric intubation to male mice at a dose of 50 mg/kg, was active h Water and methanol extracts of the seed, on agar plate at a concentration of 100 mg/mL, were inactive on Bacillus subtilis H-17 (Rec+) and Salmonella typhimurium TAIOO and TA98. Metabolic activation had no effect on the results h... 

Mutagenic activity. Methanol extract of the fresh root, on agar plate, was inactive on Salmonella typhimurium TA98 and TAIOO . Root juice, on agar plate at a dose of 200 pL/mL, produced weak activity on Salmonella typhimurium TAIOO and a dose of 400 pL/mL was inactive on SalmO nella typhimurium TA98 . 

Mutagenic activity. Ethanol (95%) extract of the dried resin, on agar plate at a concentration of 15 mg/plate, produced weak activity on streptomycin-dependent strains of Salmonella typhimurium TA98. Metabolic activation has no effect on the result " """. Resin, on agar plate at a concentration of 200 pg/plate, was active on Salmonella typhimurium TA1537 and inactive on Salmonella typhimurium TA1538 and Salmonella typhimurium TA98 " """. 

Monophasic action potential. Glycerin/ ethanol extract of the fresh leaf, administered intragastrically to dogs at a dose of 30 mg/kg, increased duration of ventricular monophasic action potential (16%) . Mutagenic activity. Ethanol (100%) extract of the fresh leaf, on agar plate, was active on Salmonella typhimurium T1530 . Natural-killer cell enhancement. Fixed oil of embryos, administered orally to adults, was inactive . Nonsaponifiable fraction of fruit fixed oil and seed oil, administered to rats at a dose of 0.3% of diet, were active. The polyphenol stripped seed oil was inactive . 

Mutagenic activity. Tetrahydrofuran extract of the fruit, at a concentration of 9 mg/mL, was inactive on Gambusia affinis sperm k... 

Members of another class of powerful direct mutagens, four nitroazabenzo[a]pyrene derivatives, were identified by Sera and co-workers (1994) in the basic fraction of extracts of diesel exhaust and in ambient POM. Structures and direct mutagenic activities on strains TA98 and YG1024 (-S9 mix) of the 1- and 3-nitro-6-azabenzo[a]pyrenes and the 1- and 3-nitro-6-azabenzo[a]pyrene-7V-oxides are shown in Table 10.21 (Sera et al., 1992 Fukuhara et al., 1992). They have been measured in ambient air in Fukuoka, Japan, at concentrations of 1.1, 1.2, 0.8, and 0.3 ng/g, respec-... 

The effect on reactive compounds and potential alteration of mutagenic activity of the acid-base extraction procedure were major concerns. The TLC method was not recommended because of possible mutagen loss due to reactions on the plate. The Florisil and low-pressure chromatographic methods were considered to be research methods. 

Figure 8. Variations in mutagenic activity of fish bile extracts of the Rhine...

Many questions remain as to the most appropriate extraction or concentration procedures. Nevertheless, residues from similar water sources have now been obtained by using a variety of techniques. The patterns of mutagenic activity obtained from these residues are sufficiently similar so that it is clear the mutagens are generally not artifacts of concentration. Chemical assays and bioassays of these mixtures typically reveal that among the thousands of largely unknown compounds present at low concentrations, there is a diverse minority of mutagens. 

Ames Test. Salmonella tryphimurium strains TA98 and TA100 were employed according to the Ames test (15, 16) to determine the mutagenic activity of the various water samples. Each DCM and MeOH extract was tested with and without S9 (microsomal fraction of activated rat liver with Arochlor 1254) activation. For each assay (16 assays per sampling point), the number of revertants per plate was plotted versus increasing volumes of water extracts injected. Slope values from linear regression of the dose-response curves were calculated and then used in the statistical analysis. 

Disinfection with Chlorine and Chlorine Dioxide. The comparison of the mutagenic activity of the DCM extract before and after disinfection treatment was studied by the Wilcoxon test. No statistical conclusions on disinfection effects can be drawn. However, the MeOH extract showed a significant decrease in mutagenic activity for the line 2 chlorine treatment. Comparison of the two disinfection treatments for the nonozonated GAC filtered water (treatment line 4) shows that chlorine disinfection yields greater mutagenic activity of the DCM extract than chlorine dioxide (Table V). 

Complete Treatment Line. The Wilcoxon test was applied to compare mutagenic activity before RSF and after complete treatment lines. Treatment line 4 with chlorine dioxide disinfection significantly decreased the mutagenic activity of the DCM extract. No other statistically significant differences were observed for any other treatment lines from data on DCM or MeOH extracts (Table VI). 

Concentrated extracts of many drinking waters in the United Kingdom and elsewhere are mutagenic as observed in bacterial assays (i-3). Compounds that are widely distributed in the aquatic environment, such as humic substances and amino acids, have been found to react with chlorine to produce mutagenic compounds (4, 5). These compounds may account for at least some of the mutagenic activity of extracts of drinking waters. 

HPLC Fractionation of Extracts of Treated Water. Capillary GC-MS analysis of the XAD-2/ethyl ether extracts of water sampled before and after final chlorination showed no significant difference that could account for the mutagenic activity observed after chlorination. These results indicate that the mutagenic compounds present in the extracts of drinking water are not readily amenable to analysis by GC-MS. However, the possibility cannot be excluded that the mutagenic compounds were present below the detection limit or that they were masked by other compounds. 

Figure 1. Comparison of TA100 mutagenic activities in treated waters sampled before and after chlorination (a) XAD-2/ethyl ether extracts and (b) freeze-dried/methanol extracts.

The mutagenic activities of the chlorinated humic acid and amino acid solutions are of the same order of magnitude as that observed in treated water. (The low numbers of revertants at the higher dose levels indicate toxicity). Therefore, these compounds may be precursors of the mutagenicity that is observed in XAD-2/ethyl ether extracts of treated water and that is the direct result of chlorination in drinking water treatment. 

Table I shows the results of the mutagenicity assays and some products of chlorination identified in the extracts by GC-MS. With the exception of glycine, mutagenic activity was observed in all the extracts of chlorinated amino acids.

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