Rapid enhanced photocatalytic degradation of dyes using novel N-doped ZrO2

A novel N-doped ZrO2 (N-ZrO2) photocatalyst is synthesized through thermal decomposition of zirconium hydroxide-urea complex and is characterized using various techniques, including XRD, FTIR, TGA, SEM, TEM, UV-DRS, XPS, XANES, and BET. The N-ZrO2 possesses pure monoclinic structure with high crystallinity. By using the proposed facile route of synthesis, both interstitial and substitutional N doping with high dopant stability can be realized. The optical properties of the catalyst are significantly altered after N doping, giving an optical response in the visible and near infrared regions and an additional strong absorption peak in the UVA region. The N-ZrO2 showed a higher photocatalytic activity than pristine ZrO2 for the degradation of amaranth (AM) and methylene blue (MB) under visible or UV light irradiation, which could be attributed to the band gap narrowing, higher specific area, smaller crystalline size, and higher availability of surface hydroxyl groups. Due to its molecular structure and light absorption characteristics, MB is easier to degrade than AM. Overall removal efficiencies, including adsorption and photolysis, for AM and MB by N-ZrO2 at pH 7 with initial dye concentration of 10 mg/L, catalyst concentration of 1 g/L, and visible light irradiation of 144.7 W/m(2) are 67.2 and 96%, respectively. Using UVA light of only 3.5 W/m(2) under identical experimental conditions, complete removal of MB and AM is obtained. The photocatalytically treated solution of either AM or MB is nontoxic against Bacillus cereus, an agriculturally important soil microorganism.

Cholestasis induced by model organic anions protects from acetaminophen hepatotoxicity in male CD-1 mice

Administration of the non-metabolizable organic anion indocyanine green (ICG) prior to a toxic dose of acetaminophen (4-acetamidophenol; APAP) reduces liver injury 24h after dosing. ICG also produces a dose-dependent decrease in bile flow in mice and rats. Studies in bile duct-cannulated rats suggest that cholestasis can play a role in this protection. This study was conducted to determine if the ability of model organic anions to produce cholestasis is relevant to the protection against APAP hepatotoxicity afforded by ICG. In these studies, overnight fasted male CD-1 mice were dosed (i.v.) with the cholestatic dyes bromcresol green (BCG, 30 micromol/kg) and rose bengal (RB, 60 micromol/kg) immediately prior APAP administration (500 mg/kg, i.p.). Other groups of mice received the non-cholestatic dyes dibromosulphthalein (DBSP, 150 micromol/kg) and amaranth (AM, 300 micromol/kg) prior to APAP. Controls were given vehicle only. Hepatocellular necrosis was evident at 24 h in control mice receiving APAP. Pretreatment with the cholestatic dyes BCG and RB decreased the severity of hepatocellular necrosis induced by APAP. However, administration of the non-cholestatic dyes DBSP and AM did not alter APAP-induced liver damage. Glutathione replenishment was not altered by pretreatment with any of these dyes. Furthermore, ICG protected mice against carbon tetrachloride (CCl4) hepatotoxicity. Since CCl4 undergoes minimal biliary excretion and does not compete for biliary transport function, this finding supports the notion that cholestasis itself rather than competition for canalicular transporters is central to the hepatoprotection by ICG and other cholephilic dyes.

Influence of synthetic and natural food dyes on activities of CYP2A6, UGT1A6, and UGT2B7

Synthetic or natural food dyes are typical xenobiotics, as are drugs and pollutants. After ingestion, part of these dyes may be absorbed and metabolized by phase I and II drug-metabolizing enzymes and excreted by transporters of phase III enzymes. However, there is little information regarding the metabolism of these dyes. It was investigated whether these dyes are substrates for CYP2A6 and UDP-glucuronosyltransferase (UGT). The in vitro inhibition of drug-metabolizing enzymes by these dyes was also examined. The synthetic food dyes studied were amaranth (food red no. 2), erythrosine B (food red no. 3), allura red (food red no. 40), new coccine (food red no. 102), acid red (food red no. 106), tartrazine (food Yellow no. 4), sunset yellow FCF (food yellow no. 5), brilliant blue FCF (food blue no. 1), and indigo carmine (food blue no. 2). The natural additive dyes studied were extracts from purple sweet potato, purple corn, cochineal, monascus, grape skin, elderberry, red beet, gardenia, and curthamus. Data confirmed that these dyes were not substrates for CYP2A6, UGT1A6, and UGT2B7. Only indigo carmine inhibited CYP2A6 in a noncompetitive manner, while erythrosine B inhibited UGT1A6 (glucuronidation of p-nitrophenol) and UGT2B7 (glucuronidation of androsterone). In the natural additive dyes just listed, only monascus inhibited UGT1A6 and UGT2B7.

DNA damage induced by red food dyes orally administered to pregnant and male mice

We determined the genotoxicity of synthetic red tar dyes currently used as food color additives in many countries, including JAPAN: For the preliminary assessment, we treated groups of 4 pregnant mice (gestational day 11) once orally at the limit dose (2000 mg/kg) of amaranth (food red No. 2), allura red (food red No. 40), or acid red (food red No. 106), and we sampled brain, lung, liver, kidney, glandular stomach, colon, urinary bladder, and embryo 3, 6, and 24 h after treatment. We used the comet (alkaline single cell gel electrophoresis) assay to measure DNA damage. The assay was positive in the colon 3 h after the administration of amaranth and allura red and weakly positive in the lung 6 h after the administration of amaranth. Acid red did not induce DNA damage in any sample at any sampling time. None of the dyes damaged DNA in other organs or the embryo. We then tested male mice with amaranth, allura red, and a related color additive, new coccine (food red No. 18). The 3 dyes induced DNA damage in the colon starting at 10 mg/kg. Twenty ml/kg of soaking liquid from commercial red ginger pickles, which contained 6.5 mg/10 ml of new coccine, induced DNA damage in colon, glandular stomach, and bladder. The potencies were compared to those of other rodent carcinogens. The rodent hepatocarcinogen p-dimethylaminoazobenzene induced colon DNA damage at 1 mg/kg, whereas it damaged liver DNA only at 500 mg/kg. Although 1 mg/kg of N-nitrosodimethylamine induced DNA damage in liver and bladder, it did not induce colon DNA damage. N-nitrosodiethylamine at 14 mg/kg did not induce DNA damage in any organs examined. Because the 3 azo additives we examined induced colon DNA damage at a very low dose, more extensive assessment of azo additives is warranted.

[Influence of amaranth on the production of alpha-amylase using Aspergillus niger NRRL 3112]

In this paper the influence of the amaranth seed meal and the aeration conditions on the alpha-amylase production by Aspergillus niger NRRL 3112 were studied. The assays of selection of culture medium were carried out in a rotary shaker at 250 rpm and 2.5 cm stroke. The aeration conditions were studied in a mechanically stirred fermentor New Brunswick type. A concentration of alpha-amylase of 2750 U.Dun/ml was achieved at 120 h with a dry weight of 8.0 g/l, using a base medium with 5.0 g/l Amaranthus cruentus seed meal. In the experiment performed in a New Brunswick fermentor, the highest value was 2806 U.Dun/ml. This result was obtained after 120 h, operating at 300 rpm and an airflow of 1 l/l. min. in a limited dissolved oxygen concentration. It was determined that the increase in the agitation rate was not favorable to the enzyme production, despite that an increase was verified in the dissolved oxygen. The morphology of the microorganism, in long and ramified hyphae, was the critical factor to obtain higher levels of alpha-amylase.

Effect of feeding amaranth (food red no. 2) on the jejunal sucrase and digestion-absorption capacity of the jejunum in rats

To clarify the effect of feeding 5% amaranth (Food Red No. 2, Am) alone or with 5% dietary fiber on jejunal mucosal integrity, change in jejunal sucrase activity before and after the feeding was compared between rats fed and fasted previously. Digestion-absorption capacity of the jejunum was also examined by perfusing 15 mmol/liter sucrose and 30 mmol/liter glycylglycine through the anesthetized rat jejunum after 14 days of feeding Am. Gobo dietary fiber (GDF) was prepared from the roots of edible burdock (Arctium lappa L.). At the end of 3 days' fasting, rats had 20% less body weight, 30% less mucosal protein and 50% less jejunal sucrase activity per unit length than those before fasting. Although rats fed Am showed severe diarrhea and growth retardation as observed in previous reports, initial sucrase level was not changed by feeding Am for 3 days even in the fasted rats. When sucrase activity on day 3 after feeding was compared among inter-groups, however, rats fed Am showed sucrase activity lower than that of rats fed either the basal diet or the basal diet containing Am plus GDF only when they had been fasted previously. After 14 days of feeding, rats fed Am after 3 days' fasting regained sucrase activity up to that of rats fed the basal diet despite the remarkable growth retardation. Jejunal perfusion in situ showed that digestion-absorption capacity for sucrose and glycylglycine in rats fed 5% Am for 14 days was also the same as that in rats fed the basal diet. These results suggest that feeding Am can reduce neither jejunal sucrase nor digestion-absorption capacity of epithelial cells of the jejunum, but retards the regain of the lowered sucrase level at earlier stage of feeding when rats have been fasted before the feeding, and that concurrent feeding of GDF promotes catch-up of the sucrase level lowered by the fasting.

Continuous live-dead discrimination of ram sperm during freezing

Use of the dye amaranth (Color Index 16185) as a supravital stain for ram sperm is described. At a concentration of 0.4% in diluted semen, the dye was completely excluded by motile sperm and had no effect on sperm motility. The nuclei of immotile sperm were stained pink by amaranth. The decrease in sperm motility during 24-h storage at 5 degrees C was accompanied by a corresponding increase in stained sperm nuclei. The presence of the dye during freezing had no effect on sperm cryosurvival but tended to reduce sperm motility during post-thaw incubation. Insemination of ewes with fresh semen containing amaranth or with semen frozen in the presence of amaranth resulted in pregnancies in 7/10 ewes in each group, compared to 6/9 in the case of ewes inseminated with fresh semen without dye.

Red dye No. 2 and the red pigment carmine enhance aryl hydrocarbon hydroxylase and guanylate cyclase activities

The food coloring amaranth (F, D and C red No. 2) and the red pigment carmine, but not erythrosine (F, D and C red No. 3), caused a twofold enhancement of two enzymes (aryl hydrocarbon hydroxylase and guanylate cyclase) that have been linked with chemical carcinogenesis. Dose response relationships revealed that carmine enhanced both enzymes to near maximal levels at concentrations as low as 1 to 10 nM while amaranth needed a concentration of 100 nM to cause a maximal enhancement. These data suggest that amaranth and carmine mimic the effects of some chemical carcinogens at the cellular level, but erythrosine does not mimic any of these effects.

Amaranth suppresses the mutagenicity of 2-acetylaminofluorene by lowering the concentration of NADPH in top agar

Addition of 1 mg amaranth (FD&C Red No. 2) to the top agar of Salmonella/S9 assay plates decreased the yield of revertants induced by 20 micrograms 2-acetylaminofluorene (AAF) by over 50% and additional amaranth completely eliminated the mutagenic response. Similar suppression of AAF mutagenicity was seen with sulfonazo III, another azo dye. The suppressive effect of amaranth was greatest at low S9 concentrations and decreased as the amount of S9 was increased. When N-hydroxyacetylaminofluorene (N-OH-AAF) was used as mutagen, amaranth had little or no effect on either the number of revertants obtained or the S9 optimum. Similarly, 1-naphthylamine-4-sulfonic acid (a reduction product of amaranth) did not significantly affect the mutagenicity of AAF. The rate of metabolism of [14C]AAF by the S9 preparations was shown to be markedly decreased by amaranth, as were the levels of both the phenolic metabolites and of N-OH-AAF. Thus, it appeared that amaranth acts by blocking the conversion of AAF to N-OH-AAF and that this effect is caused by the amaranth itself and not by its constituent amines. Further experiments indicated that amaranth greatly decreased the levels of NADPH formed in reaction mixtures comparable to S0 mix in top agar and that such reaction mixtures also metabolized amaranth to colourless compounds. It appears likely that in top agar, NADPH reacts with amaranth at a fast enough rate to limit severely the level of the reduced co-factor (which must be formed from NADPH+ by the action of endogenous glucose-6-phosphate dehydrogenase) and thus decreases the rate of activation of mutagens by other NADPH-dependent processes.

Methodology for the testing of food dyes for genotoxic activity: experiments with red 2G (C.I. 18050)

A methodology for investigating genotoxicity of food colours using the fluctuation and DNA-repair assays with bacteria is described. In addition, a liquid repair test, developed to permit incorporation of microsomes and the quantitative estimation of cell viability, has been characterised with a number of positive control agents. Results obtained in these systems suggest that the food colour Red 2G induces repairable DNA damage and base-substitution mutation, but only in the presence of a rat-liver microsomal preparation. The significance of the data in the light of other toxicological information is discussed.

Teratological evaluation of FD&C Red no. 2 -a collaborative government-industry study. II. FDA's study

Because of recent studies indicating possible embryolethality and teratogenicity of FD&C Red No. 2, and ad hoc committee was convened by the Food and Drug Administration to consider these questions. The committee suggested a collaborative study by three laboratories [Food and Drug Administration (FDA), Industrial Bio-Test Laboratories (IBT), and National Center for Toxicological Research (NCTR)] in which Red No. 2 was given at 200 mg/kg body weight, by gavage during days 0-19, 6-15, or 7-9 of gestation. FD&C Red No. 2 was also given at the same dose level via water bottle. Appropriate controls were utilized. FDA used Osborne-Mendel strain rats, IBT used Charles River, and NCTR used both strains. No significant increases in skeletal or visceral abnormalities were seen. No significant increase in resorptions was seen in the Osborne-Mendel strain, but the Charles River strain at IBT showed a significant increase in litters with two or more resorptions after dams had been given 200 mg/kg at 0-19 days of gestation. The NCTR study on the Charles River strain also showed an increase in the same parameter for the same dose level and in addition showed a significant increase in the percentage of resorptions per litter. It was concluded that because of the inherent variation and the absence of an increase in abnormalities or other indications of embryotoxicity, there is reason to doubt that this effect is either biologically significant or reproducible.

Teratological evaluation of FD&C Red no. 2-a collaborative government -industry study. III. IBT's study

Because of recent studies indicating possible embryolethality and teratogenicity of FD&C Red No.2, an ad hoc committee was convened by the Food and Drug Administration to consider these questions. The committee suggested a collaborative study by three laboratories [Food and Drug Administration (FDA), Industrial Bio- Test Laboratories (IBT), and National Center for Toxicological Research (NCTR)] in which Red No. 2 was given at 200 mg/kg body weight, by gavage during dose level via water bottle. Appropriate controls were utilized. FDA used Osborne-Mendel stran rats, IBT used Charles River, and NCTR used both strains. No significant increases in skeletal or visceral abnormalities were seen. No significant increase in resorptions was seen in the Osborne-Mendel strain, but the Charles River stain at IBT showed a significant increase in litters with two or more resorptions after dams had been given 200 mg/kg at 0-19 days of gestation. The NCTR study on the Charles River strain also showed an increase in the same parameter for the same dose level and in addition showed a significant increase in the percentage of resorptions per litter. It was concluded that because of the inherent variation and the absence of an increase in abnormalities or other indications of embryotoxicity, there is reason to doubt that this effect is either biologically significant or reproducible.

Teratological evaluation of FD&C Red No. 2-a collaborative government -industry study. IV. NCTR's study

Because of recent studies indicating possible embryolethality and teratogenicity of FD&C Red No. 2, an ad hoc committee was convened by the Food and Drug Administration to consider these questions. The committee suggested a collaborative study by three laboratories [Food and Drug Administration (FDA),Industrial Bio- Test Laboratories (IBT), and National Center for Toxicological Research (NCTR)] in which Red No. 2 was given at 200 mg/kg body weight, by gavage during days 0-19, 6-15, or 7-9 of gestation. FD&C Red No. 2 was also given at the same dose level via water bottle. Appropriate controls were utilized. FDA used Osborne-Mendel strain rats, IBT used Charles River, and NCTR used both strains. No significant increases in skeletal or visceral abnormalities were seen. No significant increase in resorptions was seen in the Osborne-Mendel strain, but the Charles River strain at IBT showed a showed a significant increase in litters with two or more resorptions after dams had been given 200 mg/kg at 0-19 days of gestation. The NCTR study on the Charles River strain also showed an increase in the same parameter for the same dose level and in addition showed a significant increase in the percentage of resorptions per litter. It was concluded that because of the inherent variation and the absence of an increase in abnormalities or other indications of embryotoxicity, there is reason to doubt that this effect is either biologically significant or reproducible.

[Azo dyes and vitamin A reserves in the liver]

Amaranth and Sunset Yellow FCF, added to the basic diet at 1200, 3000, 10 000 and 20 000 mg/kg, influence, after 10 days' administration to rats, neither the percentage of vitamin A stored in the liver in relation to the quantity of vitamin taken, nor the hepatic reserve expressed in IU/g of liver.

A teratologic study with the dyes amaranth and Ponceau 4R in mice

A teratology study on amaranth and Ponceau 4R was carried out in NMRI mice. The substances were given by gavage either from day 0 through day 7 or from day 6 through day 18 in doses of 7.5, 30 or 100 mg/kg. Distilled water was given by gavage to the control dams from day 0 through day 18. The foetuses were removed on day 18 for detailed examinations. No effect of treatment with the dyes could be observed with regard to number of implantations, frequency of foetal death and resorptions, gross malformations, skeletal or internal malformations or retarded growth as judged by foetal weight. The results are discussed with particular reference to the evaluation of teratologic studies on food colouring in general and the various regulation proposals from the National Food Administration.