Antimicrobial properties of commercial annatto extracts against selected pathogenic, lactic acid, and spoilage microorganisms

Annatto preparations are used to impart distinctive flavor and color to foods and are a primary colorant in dairy foods such as cheese and butter. There are several reports indicating that certain fractions of the annatto plant have biological activities against microorganisms of significance in food fermentation, food preservation, and human health. However, little is reported describing the nature of the antimicrobial compound(s) or their potential presence in commercial annatto colorant preparations. This study was conducted to determine whether commonly available annatto extracts are capable of influencing the outgrowth of selected lactic acid, spoilage, and pathogenic microorganisms. Disk diffusion and tube macrodilution techniques were used to determine the MICs and MBCs of double-strength water-soluble annatto extracts. Standard antibiotic disks were used as controls for the disk diffusion assay. The results demonstrate that annatto has an inhibitory effect on Bacillus cereus, Clostridium perfringens, and Staphylococcus aureus, with MICs of 0.08, 0.31, and 0.16% (vol/vol) and diameters of inhibition of 9 to 10, 12 to 13, and 15 to 16 mm, respectively. A concentration of 0.63% (vol/vol) inhibited the growth of Streptococcus thermophilus, Lactobacillus casei subsp. casei, Lactococcus lactis, and Paenibacillus polymyxa. The MICs for Listeria monocytogenes and Enterococcus durans were 1.25 and 2.5% (vol/vol), respectively. No activity was detected against Lactobacillus plantarum, Bifidobacterium bifidum, yeasts, or selected gram-negative bacteria.

Synthetic organic hard capsule colouring agents: in vitro effect on human true and pseudo-cholinesterases

Hard capsules are made of pure gelatin and small quantities of additives, including colouring agents permitted for use in food. In this study, the effects of three colouring agents (sunset yellow, quinoline yellow and erythrosine) on true and pseudo-cholinesterases (ChE) are assessed in erythrocytes and plasma, respectively. Results indicated that the synthetic compounds affected both true and pseudo ChE activity. The concentration of sunset yellow which caused 50% inhibition (IC50) of true ChE was about 64% that of pseudo-ChE; for erythrosine, IC50 was approximately the same for both true and pseudo-ChE; and for quinoline yellow, IC50 for true ChE was 25% of pseudo-ChE, although its effect on both true and pseudo-ChE was greater than seen with the other two dyes. Inhibitions of both true and pseudo-ChE were of mixed type (competitive and non-competitive). The enzyme-inhibitor dissociation constant (Ki) indicated that quinoline yellow was most potent and erythrosine was least potent out of the three compounds. Inhibition of both true and pseudo-ChE by each of the three dyes was abolished by dialysis, indicating that the effects were reversible.

Preventive effects of anthraquinone food pigments on the DNA damage induced by carcinogens in Drosophila

We have previously demonstrated the inhibitory effect of chlorophyllin, a green food additive, on the genotoxicities of various carcinogens in Drosophila. Recently, we reported that purpurin, a component of a red food additive produced from madder root (Rubia tinctorium), inhibits the bacterial mutagenicity of heterocyclic amines. In the present study, we examined antigenotoxic activities of various pigments that are either constituents of food or food additives, using Drosophila in vivo DNA repair assay. Third instar larvae of Drosophila were fed a mutagen with or without pigment. The resulting adult flies were monitored for their male (repair deficient)/female (repair proficient) ratios, which reflect the DNA damage. We tested a total of 20 pigments, which are mainly of plant origins, including flavonoids, carotenoids, anthocyanins, anthraquinones and beta-diketone (curcumin)-derivatives, against the genotoxicities of eight carcinogens; IQ, MeIQx, AFB1, NDMA, 2-AAF, DMBA, 4NQO, and MNU. Four anthraquinone pigments (alizarin, purpurin, lac color, and cochineal extract) showed significant antigenotoxic activities. Alizarin and purpurin suppressed the DNA damage induced by IQ, MeIQx, AFB1, NDMA, 2-AAF, DMBA, and MNU. Lac color and cochineal extract showed inhibition against IQ, MeIQx, AFB1, 2-AAF and DMBA. In these inhibitions, suppression of metabolic enzymes may be involved. Since purpurin and alizarin suppressed the activity of MNU, a direct alkylating agent, there may also be a mechanism distinct from enzyme inhibitions in these anthraquinone-mediated suppressions of DNA damage.

Synergistic effects of food colors on the toxicity of 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole (Trp-P-1) in primary cultured rat hepatocytes

The synergistic effect of food additives or food colors on the toxicity of 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole (Trp-P-1) was investigated using primary cultured rat hepatocytes. When hepatocytes from rats fed a standard diet were treated with a mixture of four major food additives (sorbitol, sodium L(+)-glutamate, benzoic acid, and propylene glycol) or a mixture of six typical artificial food colors (erythrosine, allura red, new coccine, brilliant blue, tertrazine, and fast green), the in vitro treated food-color mixture itself showed cytotoxicity: the reduction of cell viability and decreases in the activities of gluconeogenesis and ureogenesis. The food-color mixture enhanced cytotoxicity of Trp-P-1 obviously. We then investigated the effects of in vivo-dosed food additives or food colors on Trp-P-1-caused toxicity. Hepatocytes were isolated and cultured from rats fed a diet containing a mixture of food additives or a mixture of food colors with half the amount of their respective acceptable daily intake for 4 wk. Trp-P-1 was administered to the hepatocytes at various concentrations for 12 h. Synergistic effects of in vivo-dosed food additives and food colors were not observed on Trp-P-1-caused cytotoxicity as estimated by a loss of cell viability and the reductions of DNA and protein syntheses. On the contrary, we have observed that in vivo administered food colors synergistically facilitated to reduce the activities of gluconeogenesis and ureogenesis in Trp-P-1-treated hepatocytes. These results suggest that the daily intake of artificial food colors may impair hepatic functions such as gluconeogenesis and ureogenesis, when dietary carcinogens are exposed to the liver cells.

Evaluation of colour and hardness changes of soft lining materials in food colorant solutions

The aim of this study was to measure the colour stability and viscoelastic properties of three commercially available soft lining materials in vitro, by exposing them to 3% erythrosine, tartrazine and sunset yellow solutions. The colour changes were determined using a computer controlled spectrophotometer. The colour change of three soft lining materials--Molloplast B, Flexor and Coe Super Soft--were determined after 1, 3 and 6 months storage in three different food colorant solutions. The colour changes of Molloplast B was not noticeable. Only the initial colour value of Flexor was significantly different from the other time interval colour measurements. On the other hand, the colour difference of Coe Super Soft was found to be significantly different at all comparative time interval measurements (P<0.05). According to Shore A hardness values, Molloplast B had an initial hardness of 44 in all three solutions, and there was a slight increase after 6 months. Flexor had an initial hardness of 39, at the end of 6 months the hardness changed a little. Coe Super Soft was fairly hard after processing and Shore A hardness was initially 89 which increased to 95 later on. According to these results, only the hardness values of Coe Super Soft showed a statistically significant difference when compared using Wilcoxon signed rank test at the P<0.05 level. As a conclusion, silicon type soft lining material seems to be more resistant to colour change and hardness than the acrylic type soft liners.

Antibacterial activity of turmeric oil: a byproduct from curcumin manufacture

Curcumin, the yellow color pigment of turmeric, is produced industrially from turmeric oleoresin. The mother liquor after isolation of curcumin from oleoresin contains approximately 40% oil. The oil was extracted from the mother liquor using hexane at 60 degrees C, and the hexane extract was separated into three fractions using silica gel column chromatography. These fractions were tested for antibacterial activity by pour plate method against Bacillus cereus, Bacillus coagulans, Bacillus subtilis, Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. Fraction II eluted with 5% ethyl acetate in hexane was found to be most active fraction. The turmeric oil, fraction I, and fraction II were analyzed by GC and GC-MS. ar-Turmerone, turmerone, and curlone were found to be the major compounds present in these fractions along with other oxygenated compounds.

Color stability of denture base acrylic resins in three food colorants

STATEMENT OF PROBLEM

Three commonly used artificial dyes in food technology are erythrosine, tartrazine, and sunset yellow.

PURPOSE

The color stability of 5 commercially available denture base acrylic resins (QC-20, Meliodent, Trevalon, Trevalon High, and Lucitone) was studied in vitro.

METHODS

The specimens were exposed to 3% erythrosine, tartrazine, and sunset yellow solutions at 23 degrees C +/- 1 degrees C. Color changes were determined with a computer-controlled spectrophotometer. Five specimens from each material were processed, and initial color measurements were made after 1, 3, and 6 months of exposure to the staining solutions. Finally, the color stability was quantitatively measured again, and color differences (DeltaE) were calculated.

RESULTS

For the observations made in 1, 3, and 6 months intervals, the specimens that exhibited the least color change were in the sunset yellow solution. The greatest color changes observed according to the National Bureau of Standards unit system were Lucitone (2.71) in erythrosine solution, Lucitone (2.54), QC-20 (1.71) in tartrazine solution, and QC-20 (1.66) in sunset yellow solution. The changes in the other acrylic resins in the 3 solutions were slight and at trace level.

CONCLUSIONS

All materials tested were acceptable from the standpoint of color stability for long-term exposure to these food colorants.

Biological activities of oligoketide pigments of Monascus purpureus

Rubropunctatin (1), monascorubrin (2), monascin (3) and ankaflavin (4) were purified from the mycelium of Monascus purpureus by flash chromatography on silica gel or reversed phase. Their embryotoxicity towards chicken embryos decreased in the order 2 > 1 > 3 > 4. The lower homologues 1 and 3 exhibited teratogenic effects on these organisms. Significant antibiotic activities against Bacillus subtilis and Candida pseudotropicalis were found with compounds 1 and 2. Immunosuppressive activity on mouse T-splenocytes was most pronounced with compounds 3 and 4. None of the compounds showed significant cytotoxic activity towards rat hepatocytes in vitro. Incubation of resting cells of M. purpureus with glycine afforded the dark-red compounds 5 and 6 where the pyran moiety of 1 and 2 changed into the N-substituted dihydropyridine moiety by replacement of the O-atom by the amino group of glycine. Compounds 5 and 6 were less biologically active than the major pigments 1-4.

The influence of two carotenoid food dyes on clastogenic activities of cyclophosphamide and dioxidine in mice

The influence of the food dyes E160e (beta-apo-8'-carotenal in an oil suspension) and E160a (beta-carotene in an oil suspension) on clastogenic effects of cyclophosphamide (CP) and dioxidine (DN) was investigated. Chromosome damage in the bone marrow of C57BL/6 mice was reported. The following protocols were used: (1) simultaneous single administration of the dye and the mutagen and the subsequent animal sacrifice within 24 hr; (2) a 4-day pretreatment with the dye (daily administrations) followed with simultaneous injection of the dye and the mutagen on the 5th day 24 hr before sacrifice; (3) daily co-administration of the dye and the mutagen for 5 days with sacrifice 6 hr after the last administration. CP at a dose of 30 mg/kg and DN at 300 mg/kg were injected intraperitoneally; the dyes at doses of 0.5, 5 and 50 mg/kg were given orally. Under all the protocols applied, E160e at a dose of 50 mg/kg caused a significant reduction of both DN and CP effects. At 5 mg/kg this dye reduced the effects of the mutagens only under the pretreatment regimen. Pretreatment with E160a at doses of 5 and 50 mg/kg resulted in a meaningful reduction of the DN effect. Under the combined treatment with mutagens this dye reduced both CP and DN effects.

The immunomodulatory compound 2-acetyl-4-tetrahydroxybutyl imidazole causes sequestration of lymphocytes in non-lymphoid tissues

2-Acetyl-4(5)-(1,2,3,4-tetrahydroxybutyl) imidazole (THI) is an immunomodulatory compound which causes a reversible lymphopenia in mice by an unknown mechanism. In this study, we investigated the whereabouts of cells lost from the blood and the spleen during THI treatment Homing studies following is injection of fluorescently labelled splenocytes into THI-pretreated recipients showed that THI increased labelled cells in the liver, lungs and kidneys of THI-treated mice. Furthermore, the sequestration in the liver occurred just 1.5 h after injection of labelled cells with the increase still being present at 24 h after injection. Microscopic examination of liver sections indicated that fluorescent lymphocytes were clustered within the liver sinusoids in THI-treated mice, possibly associated with endothelial cells. The liver retention of lymphocytes was confirmed by immunohistochemical studies which showed a significant increase of T cells in the liver of THI-treated mice. To determine the subset of lymphocytes which are lost from the spleen and sequestered in non-lymphoid organs, lymphocytes remaining in the spleen after THI treatment were characterized. Our results confirmed that THI reduced B cells, CD4+ and CD8+ T cells and cells expressing CD62L, CD44 and IL-2R in the spleen.

Inhibition of 12-O-tetradecanoylphorbol-13-acetate induced Epstein-Barr virus early antigen activation by natural colorants

Natural colorants such as anthocyanins, betalains, carotenoids, curcuminoids and chlorophylls have been widely used in the food processing industry and in beverages. Most of these colorants constitute part of human dietary components and are considered to be harmless and non-toxic. As a part of the study of natural products to identify non-toxic cancer chemopreventive agents, we have investigated several natural colorant extracts from vegetables and fruits of daily human consumption for their cancer chemopreventive action using the short-term in vitro assay which involves inhibition of Epstein-Barr virus early antigen activation (EBV-EA) induced by phorbol esters. Our study has identified several plant extracts that show profound activity in the EBA assay.

Growth performance and intestinal microbial populations of growing pigs fed diets containing sucrose thermal oligosaccharide caramel

Four experiments were conducted to determine growth performance and changes in intestinal microbial populations of growing pigs fed diets containing sucrose thermal oligosaccharide caramel (STOC). Ninety-six barrows and 96 gilts were group-fed experimental nursery diets for 32 d after weaning in both Exp. 1 and 2. For each experiment, pigs were divided into four groups of 48 pigs and were fed either control, antibiotic (Apramycin sulfate, 34 mg/kg), 1% STOC, or 2% STOC diets for 32 d after weaning. Each diet was replicated six times with eight pigs per replication. Pigs were either orally gavaged (Exp 1) with water of STOC (2 g per pig) or pigs were creep-fed (Exp 2) either a control diet or a 2% STOC diet for 5 d before weaning (33 d). At the end of Exp 1 and 2, cecal material was collected for enumeration of total aerobes, total anaerobes, coliforms, lactobacilli, and bifidobacteria. Gilts (96 per experiment) used in Exp. 3 and 4 were weaned at 26 d and fed experimental nursery diets for 32 d. They were fed either a control or 1% STOC diet and were otherwise treated as previously described. There were no significant effects of STOC or antibiotic on ADG, ADFI, feed efficiency, or cecal microbial populations in pigs in this study. Feeding diets containing either antibiotic of STOC did not improve animal performance or change intestinal bacterial populations in the present study.

Effect of natural food colorings on immunoglobulin production in vitro by rat spleen lymphocytes

Water-soluble (cacao pigment, cochineal pigment, corn pigment, betanin, carthamus yellow, and monascus pigment) and water-insoluble (gardenia yellow, laccaic acid, bixin, and curcumin) natural colorings inhibited IgE production by rat spleen lymphocytes at 10 and microM, respectively. Although many of these colorings only inhibited the production of IgG and IgM at high concentrations, the water-insoluble colorings enhanced IgM production even at 1 microM. These results suggest that natural colorings have immunoglobulin production-regulating activity.

Effect of organic synthetic food colours on mitochondrial respiration

Eleven organic synthetic dyes, currently or formerly used as food colours in Brazil, were tested to determine their effect on mitochondrial respiration in mitochondria isolated from rat liver and kidney. The compounds tested were: Erythrosine, Ponceau 4R, Allura Red, Sunset yellow, Tartrazine, Amaranth, Brilliant Blue, Blue, Fast Red E, Orange GGN and Scarlet GN. All food colours tested inhibited mitochondrial respiration (State III respiration, uncoupled) supported either by alpha-ketoglutarate or succinate. This inhibition varied largely, e.g. from 100% to 16% for Erythrosine and Tartrazine respectively, at a concentration of 0.1 mg food colour per mitochondrial protein. Both rat liver and kidney mitochondria showed similar patterns of inhibition among the food colours tested. This effect was dose related and the concentration to give 50% inhibition was determined for some of the dyes. The xanthene dye Erythrosine, which showed the strongest effect, was selected for further investigation on mitochondria in vivo.

Dietary staining in vitro by mouthrinses as a comparative measure of antiseptic activity and predictor of staining in vivo

Extrinsic staining of teeth is a side-effect of some antiseptic mouthrinses. However, few of the many rinse products available to the general public have been investigated for their propensity to cause staining. Dietary factors play an aetiological role in staining and have been used in vitro to study and compare the activity of rinses. The aim of this study was to assess rinse products for staining in vitro and, through the staining reaction, to compare the activity of products containing the same ingredients. Perspex blocks, with or without saliva pretreatment, were soaked in rinses for 2 min, washed and placed in a standard tea solution for 60 min and then the optical density (OD) read on a spectrophotometer. The cycle was repeated 10 times for saliva and 17 times for no saliva specimens or until the maximum OD was exceeded. A series of three separate experiments was performed by this method. The maximum OD was not exceeded by any product before seven passages and therefore data were compared at six passages. For most products OD increased with saliva pretreatment. Some cetylpyridinium chloride (CPC) rinses stained comparably to a chlorhexidine rinse. CPC rinses, most of which contained the same concentration of the antiseptic, varied considerably in their propensity to induce staining and one was little different to water controls. A 0.1% chlorhexidine rinse stained slightly more than a 0.2%. A phenolic/essential oil product produced some staining but zinc, triclosan and other essential oil rinses did not stain.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of subchronic exposure to Caramel Colour III on the immune system in mice

Administration of Caramel Colour III is associated with lymphopenia in laboratory animals, especially if the animals are fed a vitamin B6-deficient diet. Recently, functional immunological alterations in rats exposed to Caramel Colour III have been reported. The component of Caramel Colour III that is responsible for the immunological effects has been shown to be 2-acetyl-4-tetrahydroxybutyl imidazole (THI). In the present study, female Balb/c mice fed a diet with a relatively high vitamin B6 content were exposed to 2 or 10% of a commercial Caramel Colour III preparation with a low THI content (less than 25 ppm) in the drinking water for 9 wk. Although this treatment did not induce a lymphopenia in the exposed mice, flow cytometric analysis of lymphocyte subpopulations demonstrated reductions in the CD4+ and CD8+ cell populations. In addition, the proliferative response of spleen cells to B and T cell mitogens was significantly reduced in the mice exposed to 2% Caramel Colour III. No changes were observed in natural killer cell activity or in the humoral antibody response to a viral antigen. The results indicate that Caramel Colour III that meets the specified limit of less than 25 mg THI/kg may, nevertheless, interfere with the lymphoid system in mice with an adequate vitamin B6 status.

Effects of chronic consumption of metanil yellow by developing and adult rats on brain regional levels of noradrenaline, dopamine and serotonin, on acetylcholine esterase activity and on operant conditioning

Metanil yellow is the principal non-permitted food colour used extensively in India. The effects of long-term consumption of metanil yellow on the developing and adult brain were studied using Wistar rats. Regional levels of noradrenaline, dopamine and serotonin, activity of acetylcholine esterase (AChE), and operant conditioning with food reward were assessed in rats fed, metanil yellow and in controls. In the treated rats the amine levels in the hypothalamus, striatum and brain stem were significantly affected, and the changes were not generally reversible even after withdrawal of metanil yellow in developing rats. The striatum showed an early reduction of AChE activity, whereas the hippocampus showed a delayed but persistent effect of reduced AChE activity. Treated rats also took more sessions to learn the operant conditioning behaviour. These effects on these major neurotransmitter systems and on learning, indicate that chronic consumption of metanil yellow can predispose both the developing and the adult central nervous system (CNS) of the rat to neurotoxicity.

Reversal of aflatoxin induced liver damage by turmeric and curcumin

The effect of certain food additives on aflatoxin production by Aspergillus parasiticus has been studied in vitro. Extracts of turmeric (Curcuma longa), garlic (Allium sativum) and asafoetida (Ferula asafoetida) inhibited the aflatoxin production considerably (more than 90%) at concentrations of 5-10 mg/ml. Similar results were also seen using butylated hydroxytoluene, butylated hydroxyanisole and ellagic acid at concentration 0.1 mM. Curcumin, the antioxidant principle from Curcuma longa did not have any effect on aflatoxin production. Turmeric and curcumin were also found to reverse the aflatoxin induced liver damage produced by feeding aflatoxin B1 (AFB1) (5 micrograms/day per 14 days) to ducklings. Fatty changes, necrosis and biliary hyperplasia produced by AFB1 were considerably reversed by these food additives.

The role of lymphocyte production and migration in the lymphopenia caused by 2-acetyl-4-tetrahydroxybutyl imidazole

2-Acetyl-4-tetrahydroxybutyl imidazole (THI), a component of the food colouring ammonia caramel, has been shown to produce a profound and rapid lymphopenia in peripheral blood in the rat. In order to investigate whether the cause of the lymphopenia was due to the reduced production and influx in the circulation, redistribution of lymphocytes into other lymphoid compartments or an increased cell death, THI (1 mg/kg/day) was given in the drinking water for up to 14 days to F344 rats. A profound depletion of lymphocytes after already 1 day was only found in the blood compartment, whereas no such marked and rapid changes were found in the cellularity of other lymphoid compartments. The proportion and absolute number of DNA-synthesizing cells in each lymphoid organ was quantified using an antibody directed against incorporated 5-bromo-2'-deoxyuridine (BrdU), 1 h after a single BrdU injection. Additionally, enumeration and localization of BrdU+ cells was determined at later time points after a single BrdU injection by flow cytometry and immunocytochemistry, in order to examine the distribution and localization of recently formed (BrdU+) lymphocytes. THI treatment had no effect on the proliferation rate and the distribution of newly formed (BrdU+) cells in the lymphoid organs. However, migration studies revealed that THI treatment resulted in an increased percentage of fluorescein-labelled peripheral blood lymphocytes found in the spleen and bone marrow and a decreased percentage in the cervical and mesenteric lymph nodes, 24 h after injection. Collectively these results indicate that the lymphopenia in the peripheral blood compartment after THI treatment, is caused by a rapid sequestration of lymphocytes into the spleen and bone marrow rather than by a reduced lymphocyte production and release into the periphery. The fact that THI also caused lymphopenia in splenectomized rats, indicates that the spleen does not play an active part in the change in migrational behaviour of lymphocytes after THI treatment. Finally, as there was no increase in the absolute number of lymphocytes found in the spleen or bone marrow it seems they are rapidly degraded.

Food coloring and monosodium glutamate: effects on the cephalic phase of gastric acid secretion and gastrin release in humans

Although food additives may have a significant impact on the marketing and acceptability of food and may occasionally lead to side effects, the effect of these additives on the digestive process in humans is unknown. We evaluated whether adding coloring or monosodium glutamate to food increases the cephalic phase of gastric acid secretion or gastrin release. When ordinary food coloring or unusual food coloring was added, acid secretion and gastrin release were similar to a control study with no food coloring added. Moreover, addition of 360 mg monosodium glutamate to beef consomme soup had no effect on the acid secretory or gastrin response to the meal. Thus, the food additives studied led to no objective alteration in the gastric exocrine or endocrine response to food.

Photodynamic activities of food additive dyes on the yeast Saccharomyces cerevisiae

Photodynamic cell-inactivating activities of food additive dyes on the yeast Saccharomyces cerevisiae were investigated. Activities of dyes not permitted as food additives were also examined. Red No. 105 (rose bengal), Red No. 3 (erythrosine) and Red No. 104 (phloxine), which are permitted as food additives, markedly inactivated yeast cells by photodynamic action. Eosine, matius yellow and guinia green B, which are not permitted, also exhibited moderate cell-inactivating activity by photodynamic action. None of the dyes used in this experiment exhibited petite induction by photodynamic action.

Evaluation of azo food dyes for mutagenicity and inhibition of mutagenicity by methods using Salmonella typhimurium

The mutagenicity of 4 azo dyes (FD&C Yellow No. 5, FD&C Yellow No. 6, FD&C Red No. 40 and amaranth) that are widely used to color food has been evaluated. 4 different methods were used: (1) the standard Ames plate-incorporation assay performed directly on the dyes in the absence of S9 and in the presence of rat- or hamster-liver S9; (2) application of the standard plate assay to ether extracts of aqueous solutions of the dyes; (3) a variant of the standard assay, using hamster liver S9, preincubation, flavin mononucleotide (FMN) and other modifications designed to facilitate azo reduction; and (4) reduction of the dyes with sodium dithionite, followed by ether extraction and the standard plate assay. Assays that include chemical reduction (methods 3 and 4) were included because azo compounds ingested orally are reduced in the intestine with the release of free aromatic amines. No mutagenic activity was seen for any of the azo dyes tested by using the standard Ames plate assay (method 1). Ether extracts of some samples of FD&C Yellow No. 6, FD&C Red No. 40 and amaranth were active (method 2), but only at high doses, generally 250 mg-equivalents or more per plate. These results indicate the presence of low levels of ether-extractable mutagenic impurities. The FMN preincubation assay (method 3) gave negative results for all dye samples tested. Most batches of FD&C Red No. 40 tested had mutagenic activity that was detectable when the ether extract of less than 1 mg of dithionite-reduced dye was plated in the presence of S9 (method 4). This finding implies that an impurity in these samples of FD&C Red No. 40 can be reduced to yield an ether-extractable mutagen. Dithionite-reduced samples of FD&C Yellow No. 6 and amaranth showed ether-extractable mutagenic activity only at much higher doses than those at which activity was seen with most dithionite-reduced samples of FD&C Red No. 40 (method 4). FD&C Yellow No. 5 showed no mutagenic activity with this method. Mutagenic activity was not detected when FD&C Red No. 40 was tested by using the azo reduction preincubation assay with FMN (method 3).(ABSTRACT TRUNCATED AT 400 WORDS)

Mutagenicity, comutagenicity, and antimutagenicity of erythrosine (FD and C red 3), a food dye, in the Ames/Salmonella assay

Erythrosine (diNa, tetraiodofluorescein) was nonmutagenic to the Ames/Salmonella typhimurium strains TA97a, TA98, TA100, TA102, and TA104, to a concentration of 2 mg/plate. No mutative intermediates were detected on metabolism by rat caecal cell-free extracts or rat liver S9 mixture; or on incubation with the comutagens, harman and norharman (+/- S9). Instead, an unexpected dose-dependent suppression in spontaneous reversion frequencies was observed (maximum approximately equal to 35% decrease). Erythrosine was antimutagenic to benzo[a]pyrene, but it did not decrease the mutagenicity of the other adduct-forming mutagen, 4-nitroquinoline N-oxide. The food dye was strongly antimutagenic to the bifunctional alkylating agent, mitomycin C, though it did not exhibit a similar effect on the mutagenicity of the corresponding monofunctional agent, methyl methanesulphonate. It partially depressed the mutagenic potentials of sodium azide. The antimutagenic effect of erythrosine on an intercalating agent, ethidium bromide, was discernible only at the highest dose (2 mg/plate). These results have been interpreted in terms of a genointeractive role of erythrosine. Erythrosine produced differential toxic effects in repair-deficient (TA97a, TA98, TA100) and repair-proficient (TA102, TA104) Salmonella tester strains; survival of the repair-deficient strains was found to be decreased. Photoinduced potentiation of erythrosine toxicity was observed, although light irradiation in the presence of erythrosine did not modify the reversion frequencies of the tester strains. The evidence strongly suggests that erythrosine, which exhibits nonmutagenicity in the Ames/Salmonella test, can interact with DNA repair enzymes and/or with DNA.

In vitro inhibition of phenolsulphotransferase by food and drink constituents

Several natural and synthetic food and drink constituents were tested in vitro for their inhibitory actions on phenolsulphotransferase P and M (PST P, PST M) and monoamine oxidase A and B (MAO A, MAO B). Cyanidin 3-rutinoside, a simple anthocyanin, (+)-catechin, a flavanol, and carmoisine, a synthetic food colorant, were found to be particularly potent, reversible inhibitors of PST P. All inhibited this enzyme by 100% at a concentration of 5 microM and had an IC50 in the microM range. The effects of these compounds on PST M and MAO A and B were less pronounced. There was a considerable difference in the inhibitory ability of different purified anthocyanins but all were selective for PST P. Several other phenolic food colorants were also found to be specific inhibitors of PST P, though less potent in their actions. Tartrazine, a non-phenolic food colorant, had little effect. The phenolic extracts from two red wines were also found selectively to inhibit PST P in vitro, suggesting that it is within this fraction that these inhibitors are to be found. PST is an important enzyme involved in the inactivation of a wide range of exogenous and endogenous phenols. If such a degree of inhibition were to occur in vivo, potentially toxic concentrations of some phenolic substrates might result.

Effect of certified artificial food coloring on learning and activity level in rats

Chronic oral administration of a formula consisting of seven FD&C certified artificial food dyes, given in 0, 2.0, and 5.0 mg/kg doses, failed to produce changes in measures of physical or motor development in rat pups. Two learning tasks, one given during development and the other at maturity, also revealed no differences among groups. In addition, two activity level measures, time-sampled observations and the open field task, were taken on five occasions. These measures also failed to demonstrate any effects of food coloring. Although food dyes may have toxic effects at higher dose levels or under unusual dietary or environmental conditions, these results suggest that orally ingested low doses do not reliably elicit behavioral changes.