Formation of mutagens by pepper-nitrite reaction.
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When rhizome juice of ginger, zingiber officinale, was added to a solution of 2(2-furyl)-3(5-nitro-2-fury)acryl amide (AF2) or N-methyl-N'-nitro-N-nitrosoguanidine (NTG), mutagenesis by these chemicals was markedly increased. As a result of the component fractionation of the ginger juice, it was found that [6]-gingerol was a potent mutagen. However, the ginger juice also contained anti-mutagenic component(s) against [6]-gingerol (CAS No. 58253-27-3) (present study) and tryptophan pyrolysates (Kada et al., 1978; Morita et al., 1978). It is suggested, therefore, that the [6]-gingerol component may be mutagenically activated by the presence of AF2 and NTG.
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Soy sauce treated with nitrite was found to be more mutagenic to Escherichia coli WP2 uvrA/pKM101 than Salmonella typhimurium TA100 without S9 mix. The mutagenicity of soy sauce treated with nitrite was affected by the concentration of soy sauce in the nitrosation mixture, and a concentration of 5% resulted in the highest specific activity (revertants/ml soy sauce equivalent). By incubating soy sauce at a concentration of 5% in a solution of 1 mM nitrite at pH 3 for 1 h at 37 degrees C, the equivalent of 1 ml of soy sauce induced 2790 revertants of E. coli WP2 uvrA/pKM101 without S9 mix.
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Soy sauce pretreated with 2300 ppm nitrite caused no more aberrations than did untreated soy sauce in the chromosomal aberration test in vitro using a Chinese hamster fibroblast cell line with or without S9 mixture. The aberration induction by soy sauce is likely to be caused by the 17% sodium chloride it contains. Soy sauce with or without pretreatment with 2300 ppm nitrite was orally given to ICR mice at a dose of 14 ml/kg body weight once or 6 ml/kg body weight/day for 5 consecutive days. This oral administration did not induce any significant increase in micronuclei in the micronucleus test in vivo.
Tabasco sauce and mustard taken with the evening meal markedly disturbed sleep of six, young, healthy male subjects; reducing slow wave and stage 2 sleep, increasing total time awake and tending to increase sleep onset latency. Whilst post meal effects on temperature and oxygen consumption were not significantly different from control meals the spicy food condition elevated body temperature during the first sleep cycle. The possibility that the spice principle capsaicin affects sleep via changes in body temperature is discussed.
Bacteriological examination of 230 samples of five different unprocessed spices (aligator pepper, red pepper, black pepper, thyme and curry powder) collected randomly from Port Harcourt main markets revealed that the spices were highly contaminated, with bacterial counts ranging from 1.8 x 10(4) to 1.1 x 10(8) per gram. Bacillus cereus was isolated in high numbers in the majority of the 230 samples examined. It was also observed that other Bacillus spp. including B. subtilis, B. polymyxa and B. coagulans occurred in significant numbers.
The inhibitory effects of 10 selected Turkish spices, oregano essential oil, thymol and carvacrol towards growth of 9 foodborne fungi were investigated in culture media with pH 3.5 and 5.5. The antifungal effects of sodium chloride, sorbic acid and sodium benzoate and the combined use of oregano with sodium chloride were also tested under the same conditions for comparison. Of the spices tested, only sodium chloride were also tested under the same conditions for comparison. Of the spices tested, only oregano at 1.0, 1.5, 2.0% (w/v) levels showed effect on all fungi. 8% (w/v) sodium chloride was less effective than oregano. Oregano essential oil, thymol or carvacrol at concentrations of 0.025% and 0.05% completely inhibited the growth of all fungi, showing greater inhibition than sorbic acid at the same concentrations. The combined use of oregano and sodium chloride exhibited a synergistic antifungal effect.
Cumin at concentrations of 0.5, 1.0 and 2.0% (w/w) stimulated growth and acid production of Lactobacillus plantarum and Leuconostoc mesenteroides in a liquid medium. Essential oil from cumin at high concentrations (300 and 600 ppm) inhibited growth and acid production of Lactobacillus plantarum. After a certain period, growth of Leuconostoc mesenteroides was observed at all concentrations (150, 300 and 600 ppm) and its acid production was stimulated at 600 ppm. Oregano and its essential oil at all concentrations inhibited growth of both cultures. Acid production by Lactobacillus plantarum was stimulated by oregano spice.
Aqueous extracts of onion, garlic and ginger were found to inhibit aggregation induced by ADP, epinephrine, collagen and arachidonate in a dose-dependent manner in vitro. In the case of onion and garlic extracts relatively much higher volumes were need to bring about even a modest inhibition (by ca. 13-18%) of thromboxane synthesis in washed platelets from labelled AA. On the other hand a good correlation was found between the amounts of ginger extract needed to inhibit platelet aggregation and those to inhibit platelet thromboxane synthesis. Ginger extract reduced also platelet prostaglandin-endoperoxides. A dose-related inhibition of platelet thromboxane- and prostaglandin (PGF2 alpha, PGE2 and PGD2) synthesis was affected by ginger extract. Extracts of onion, garlic and ginger inhibited biosynthesis of prostacyclin in rat aorta from labelled AA. Ginger extract mildly inhibited the synthesis of prostacyclin from endogenous pool of AA in rat aorta; the other two extracts were without effect.
Aqueous ginger extract was extracted in three organic solvents viz., n-hexane, chloroform and ethyl acetate with increasing polarity. The extracted materials from these solvents reduced platelet thromboxane formation from exogenous arachidonate (AA) and also inhibited platelet aggregation induced by AA, epinephrine, ADP and collagen; in this respect they were most effective against AA-induced aggregation. The extracted material in n-hexane was further resolved by thin-layer chromatography into various fractions some of which were effective in inhibiting platelet thromboxane formation and platelet aggregation. Aqueous ginger extract reduced the formation of TxB2 from AA-labelled platelets without showing effects on platelet phospholipase activity. Thromboxane formation in labelled platelets on activation with calcium ionophore A23187 was reduced by ginger components, isolated from two TLC bands, in a dose-dependent manner (10-100 ug/500 ml). At the higher dose lipoxygenase products were also reduced. Interestingly the incorporation of AA into platelet phospholipids increased in platelets treated with aqueous ginger extract.
Soy sauce was heated with 100, 500, 1000 or 2000 ppm sodium nitrite for 30 min at 80 degrees C and pH 3. The reaction mixtures were extracted with dichloromethane followed by ethyl acetate. After removal of the solvents, the extracts were subjected to analysis (gas chromatograph-thermal energy analyser and gas chromatograph-mass spectrometer) and Ames mutagenicity tests. N-Nitrosodimethylamine and N-nitrosodiethylamine were found in the dichloromethane extract of the soy sauce treated with 2000 ppm nitrite at levels of 10 and 120 micrograms/ml, respectively. N-Nitrosoproline was identified in the ethyl acetate extract of the same sample at a level of 0.5 microgram/ml. Both extracts exhibited dose-related mutagenicity in Salmonella typhimurium strain TA100 with S-9 mix. The dichloromethane extract showed much higher mutagenicity than did the ethyl acetate extract. The samples obtained from soy sauce treated with 100, 500 and 1000 ppm nitrite were not mutagenic, but N-nitrosodiethylamine was detected by thermal energy analysis in the soy sauce treated with 1000 ppm nitrite. The addition of 10,000 ppm L-ascorbic acid, along with 2000 ppm nitrite, to soy sauce prevented the formation of mutagenic materials or detectable nitrosamines.
The extraction of about 1.9 kg of Ceylon cinnamon (Cinnamomum zeylanicum Nees) with 10 litres each of petroleum ether, chloroform and ethanol in a Soxhlet apparatus produced extracts weighing 76, 28 and 270 g respectively for the three solvents. In the preliminary test the ethanol extract showed no mutagenic activity. However, both the petroleum ether and the chloroform extracts showed mutagenicity when tested in the rec assay using Bacillus subtilis strains H17 (rec+) and M45 (rec-). When these extracts were studied quantitatively by the liquid and spore rec-assay methods, the minimum inhibitory concentrations of the extracts against strain H17 were higher than those against strain M45. However, in the presence of the liver S-9 mix, the minimum inhibitory concentrations of the petroleum ether and chloroform extracts against both strains of B. subtilis were equal, indicating that the mutagenicity of the extracts had been inactivated.
This study was conducted to determine the effects of nitrite (0.05% in drinking-water) and soy sauce (20% in a refined diet) on the initiation and promotion of benzo[a]pyrene-induced forestomach neoplasia in ICR mice. In two experiments nitrite and soy sauce together significantly reduced the number of neoplasms per animal. Soy sauce (without nitrite) produced a smaller apparent (non-significant) reduction whereas nitrite (without soy sauce) had no effect. Evidence suggested that soy sauce might contain factors that reduce calorie absorption or utilization, but this observation was independent of the inclusion of nitrite in the drinking-water and therefore could not by itself explain the significant reduction in neoplasms in mice given soy sauce plus nitrite. Protection appeared to primarily involve the tumour promotion stage.
Some common Nigerian foodstuffs were assessed for their content of preformed volatile nitrosamine by chemiluminescence detection following gas chromatographic separation. Nitrosodimethylamine levels of between 0.4 and 4.6 ppb were detected in 75% of the samples analysed. The highest value was found in Brassica oleraceae, while Vernonia amygdalina contained the lowest detectable level. These data suggest that Nigerians may be exposed to chronic but very low levels of carcinogenic nitrosamines in their foods.
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