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Estimated intake of the artificial sweeteners acesulfame-K, aspartame, cyclamate and saccharin in a group of Swedish diabetics.

Few sweetener intake studies have been performed on the general population and only one study has been specifically designed to investigate diabetics and children. This report describes a Swedish study on the estimated intake of the artificial sweeteners acesulfame-K, aspartame, cyclamate and saccharin by children (0-15 years) and adult male and female diabetics (types I and II) of various ages (16-90 years). Altogether, 1120 participants were asked to complete a questionnaire about their sweetener intake. The response rate (71%, range 59-78%) was comparable across age and gender groups. The most consumed 'light' foodstuffs were diet soda, cider, fruit syrup, table powder, table tablets, table drops, ice cream, chewing gum, throat lozenges, sweets, yoghurt and vitamin C. The major sources of sweetener intake were beverages and table powder. About 70% of the participants, equally distributed across all age groups, read the manufacturer's specifications of the food products' content. The estimated intakes showed that neither men nor women exceeded the ADI for acesulfame-K; however, using worst-case calculations, high intakes were found in young children (169% of ADI). In general, the aspartame intake was low. Children had the highest estimated (worst case) intake of cyclamate (317% of ADI). Children's estimated intake of saccharin only slightly exceeded the ADI at the 5% level for fruit syrup. Children had an unexpected high intake of tabletop sweeteners, which, in Sweden, is normally based on cyclamate. The study was performed during two winter months when it can be assumed that the intake of sweeteners was lower as compared with during warm, summer months. Thus, the present study probably underestimates the average intake on a yearly basis. However, our worst-case calculations based on maximum permitted levels were performed on each individual sweetener, although exposure is probably relatively evenly distributed among all sweeteners, except for cyclamate containing table sweeteners.

Adolescent↗

Metabolism of cyclamate and its conversion to cyclohexylamine.

Since cyclamates were first introduced in the early 1950s, arguments have raged over the potential carcinogenicity of this artificial sweetener. Concern over the safety of cyclamates arises from observations that some individuals and experimental animals can metabolize cyclamate to cyclohexylamine and that cyclohexylamine has been shown to produce testicular atrophy in experimental animals. This study examines the absorption, excretion, and metabolism of cyclamate, particularly its conversion to cyclohexylamine. In addition, the potential toxicity and pharmacology of cyclohexylamine are discussed.

Animals↗

[Influence of several weeks' treatment of male and female mice with saccharin, cyclamate or cyclohexylamine sulfate on fertility and dominant lethal effects (author's transl)].

The purpose of this investigation was to find out whether long-term treatment of male and female mice with saccharin sodium, sodium cyclamate or cyclohexylamine sulfate, would reduce fertility or induce dominant lethal mutations. Before mating, saccharin sodium or sodium cyclamate were added to the food in a concentration of 1%, while cyclohexylamine sulfate was added in a concentration of 0.11% for at least 10 weeks. This treatment corresponded, in the case of saccharin sodium and sodium cyclamate, to an active substance intake of approx. 2000 mg/kg per day and for cyclohexylamine sulfate to an intake of approx. 200 mg/kg per day (corresponding to approx. 136 mg cyclohexylamine per kilogram per day). These doses affected neither the females nor the males in respect of appearance, behaviour, and weight gain. The doses were also compatible with the normal fertility of the animals. Furthermore, in all cases the treatment did not cause a biologically important increase of pre-implantative and post-implantative losses. The dominant lethal tests did not indicate a mutagenic action of saccharin sodium or sodium cyclamate (1% in the food) and of cyclohexylamine sulfate (0.11% in the food) after 10 weeks' treatment of male and female mice. These results, obtained after long-term treatment, corresponded generally to the findin

Animals↗

Liposome aggregation in presence of the sweeteners cyclamate and saccharine.

The interaction of the sweeteners saccharine and cyclamate with large unilamellar liposomes and planar bilayer lipid membranes (BLM) was studied. Application of the methods of light scattering and sound velocimetry showed that saccharine induces aggregation of liposomes, while cyclamate probably caused increase of the hydration of liposome surface. The sweeteners induced changes of BLM compressibility in a direction perpendicular to the membrane plane. The cyclamate induced considerably larger decreases in the elasticity module than saccharine. The obtained results show that both saccharine and cyclamate interacts with the surface of lipid bilayer and could modify the physical properties of lipid membranes.

Cyclamates↗

Technetium-99m-cyclam AK 2123: a novel marker for tumor hypoxia.

Technetium-99m labeled cyclam N-2'-methoxyethyl-2-(3'-nitro-1'-triazole) acetamide (cyclam AK 2123) has been synthesized, radiolabeled and characterized as a hypoxic tumor imaging agent. Radiochemical purity was greater than 95%. Marker biodistribution was measured in normal Wistar strain rats at different time intervals after intra venous (i.v.) administration. In vivo distribution and scintigraphic imaging studies were performed after i.v. injection into mammary tumor-bearing rats using a gamma camera and associated computer. Intratumor partial oxygen pressure (pO2) and oxygen saturation measurements were performed to estimate the oxygenation status of the tumors. Tumor to muscle ratio (T/M) of 99mTc-cyclam AK 2123 was 8.5 which was compared with other tumor seeking radiopharmaceuticals, viz. 99mTc-(V) DMSA (3.07), 99mTc-citrate (5.29) and 201T1C1 (3.29). T/M ratios were also evaluated in comparison with radioiodinated iodoazomycin galactopyronoside (125I-IAZG). The ratio obtained was 18 for 99mTc-cyclam AK 2123 and 20 for 125I-IAZG, respectively. The increased concentration of radioactivity in these tumors suggests that this agent could be labelling hypoxic cells and have utility as an imaging agent.

Animals↗

Application of cyclam-capped beta-cyclodextrin-bonded silica particles as a chiral stationary phase in capillary electrochromatography for enantiomeric separations.

Two novel types of substituted cyclam-capped beta-cyclodextrin (beta-CD)-bonded silica particles have been prepared and used as chiral stationary phases in capillary electrochromatography (CEC). The two stationary phases have a chiral selector with three recognition sites: beta-CD, cyclam, and the latter's sidearm. They exhibit excellent enantioselectivities in CEC for a wide range of compounds as a result of the cooperative functioning of the anchored beta-CD and cyclam. After inclusion of the metal ion (Ni2+) from the running buffer into the substituted cyclams and their sidearm ligands, the bonded stationary phases become positively charged and can provide extra electrostatic interactions with ionizable solutes and enhance the dipolar interactions with some polar neutral solutes. This enhances the host-guest interaction with some solutes and improves chiral recognition and enantioselectivity. These new types of stationary phases exhibit great potential for fast chiral separations in CEC.

Chromatography↗

Syntheses of ruthenium(II) quinonediimine complexes of cyclam and characterization of their DNA-binding activities and cytotoxicity.

The synthesis and characterization of ruthenium(II) complexes, [Ru(cyclam)(bqdi)] x ZnCl(4) (1 x ZnCl(4); cyclam = 1,4,8,11-tetraazacyclotetradecane, bqdi = o-benzoquinonediimine), [Ru(cyclam)(nqdi)] x (ClO(4))(2) (2 x (ClO(4))(2); nqdi = 2,3-naphthoquinonediimine), and [Ru(cyclam)(phi)] x (ClO(4))(2) (3 x (ClO(4))(2); phi = 9,10-phenanthroquinonediimine), are described. The DNA binding properties and biological activity of the Ru(II) complexes were studied by various biophysical and cytological techniques. As expected, only 3 showed significant binding with DNA. The thermodynamic profile of the binding of 3 and DNA was constructed by analyzing the experimental data of absorption titration and UV melting studies with the McGhee equation, van't Hoff's equation, and the Gibbs-Helmholtz equation. Compound 3 binds double-stranded DNA with a binding constant of 5.0 x 10(4) M(-1) at 20 degrees C, and the binding mode of the complex to DNA was proved to be intercalative. Cytotoxicity and induced type of cell death of 1-3 were also investigated. Basically, metal complexes with ligands of molecular shape closely related to the structure of DNA are more likely to bind DNA and possess higher toxicity.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

Dendrimers as ligands. Formation of a 2:1 luminescent complex between a dendrimer with a 1,4,8,11-tetraazacyclotetradecane (cyclam) core and Zn2+.

We have investigated the formation of metal complexes between Zn2+ and two derivatives, 1 and 2, of the well-known 1,4,8,11-tetraazacyclotetradecane (cyclam) ligand. Compound 1 is 1,4,8,11-tetrakis(naphthylmethyl) cyclam, and compound 2 is a dendrimer consisting of a cyclam core with appended 12 dimethoxybenzene and 16 naphthyl units. Compound 1 exhibits an emission band with a maximum around 480 nm, assigned to the formation of exciplexes between amine and excited naphthyl units. Dendrimer 2 exhibits three types of weak emission bands, assigned to naphthyl localized excited states (lambdamax = 337 nm), naphthyl excimers (lambdamax ca. 390 nm), and naphthyl-amine exciplexes (lambdamax = 480 nm). In CH3CN-CH2Cl2 1:1 v/v, titration of ligand 1 with Zn2+ causes the disappearance of the exciplex emission and the appearance of a strong naphthyl localized fluorescence; the titration plot is linear and reaches a plateau for a 1:1 stoichiometry, showing that a highly stable [Zn(1)]2+ complex is formed. In the case of 2, titration with Zn2+ causes the disappearance of the exciplex band, with a concomitant increase in the excimer and naphthyl localized emissions; the titration plot is again linear, but in this case it reaches a plateau for a 2:1 stoichiometric ratio, showing the unexpected formation of a [Zn(2)2]2+ complex. Such an unexpected stoichiometry for the complex of the dendritic ligand has been fully confirmed by 1H NMR titrations. The results obtained show that the dendrimer branches not only do not hinder, but in fact favor coordination of cyclam to Zn2+.

Journal Article↗

High-field EPR study and crystal and molecular structure of trans-RSSR-[CrCl2(cyclam)]nX (X=ZnCl4 2-, Cl- and Cl-.4H2O.0.5HCl).

For the first time, HF-EPR (94.5 GHz) spectroscopy has been used to determine crystal field parameters in chromium(III) coordination compounds. The large zero-field splitting parameters of the dark-green photochromic trans-RSSR-[CrCl(2)(cyclam)](2)ZnCl(4), 1, the red-purple trans-RSSR-[CrCl(2)(cyclam)]Cl, 2, and the red-purple trans-RSSR-[CrCl(2)(cyclam)]Cl.4H(2)O.0.5HCl, 3, where cyclam = 1,4,8,11-tetraazacyclotetradecane, have been obtained. A full analysis of EPR spectra at 94.5 GHz of diluted complexes 1, 2 and 3 at 300 K revealed that they are extremely sensitive to D and E values. The rhombic distortion was precisely determined for each compound. For 1, g= 2.01, D=-0.305 cm(-1), E= 0.041 cm(-1) and lambda=|E/D|= 0.1396; for 2, g= 2.01; D=-0.348 cm(-1), E= 0.042 cm(-1) and lambda=|E/D|= 0.1206 and for 3, g= 1.99, D=-0.320 cm(-1), E= 0.041 cm(-1) and ambda=|E/D|= 0.1281. The EPR study at 94.5 GHz at 10 K allowed us to confirm the sign of the D value for all compounds. These data indicate that at room temperature the crystal field is mainly rhombic and as the temperature decreases, the rhombicity of the D tensor increases slightly. These found differences between 1, 2 and 3 allowed us to establish the importance of the intermolecular interactions in the solid state due to different hydrogen bonding networks in their crystalline arrangement.

Journal Article↗

The synthesis and radiolabeling of 2-nitroimidazole derivatives of cyclam and their preclinical evaluation as positive markers of tumor hypoxia.

UNLABELLED: The cyclam ligand (1,4,8,11-tetraazacyclotetradecane) was condensed with various azomycin-containing synthons to produce chemical compounds that could chelate radioactive metals. It was expected that these radiolabeled markers would become bound selectively to hypoxic cells on the bioreduction of their azomycin substituent. METHODS: The markers were radiolabeled with (99m)Tc, (67)Cu, or (64)Cu. Their uptake and binding to tumor cells in vitro was characterized as a function of time and oxygen concentration. These data defined the hypoxia-specific factor, the ratio of the initial rate of marker binding to severely hypoxic relative to aerobic cells. In addition, the concentration of oxygen (in the equilibrium gas phase) that inhibited binding to 50% of the maximum rate was determined. The in vivo biodistribution and clearance kinetics of the favorable markers were investigated with severe combined immune deficiency mice bearing EMT-6 tumors whose radiobiologic hypoxic fraction (RHF) was approximately 40%. The specific activity (percentage injected dose per gram [%ID/g]) in normal and tumor tissue and the tumor-to-blood and tumor-to-muscle ratios of the optimal markers were also measured for Dunning prostate carcinomas of anaplastic (RHF = 15%-20%) and well-differentiated (RHF < 1%) histology growing in Fischer X Copenhagen rats. Planar images were acquired with some markers from these tumor-bearing rats. RESULTS: The tumor uptake of these cyclam-based markers is approximately 10 times higher when they are labeled with copper isotopes than when labeled with (99m)Tc. FC-327 and FC-334, di-azomycin-substituted cyclams, exhibited hypoxia-specific factors > or = 7.0. The oxygen concentration that inhibited their binding to 50% of the maximal rate was approximately 0.5% O(2), similar to that of the radiobiologic oxygen effect. The %ID/g of (64)Cu-FC-334 retained in EMT-6 tumors in mice and in the anaplastic and well-differentiated prostate tumors in rats 6 h after administration was approximately 6.5, 0.4, and 0.1, respectively. Marker activity in tumor was always less than that in liver and kidney. The tumor-to-blood and tumor-to-muscle ratios of (64)Cu-FC-327 and (64)Cu-FC-334 activity in R3327-AT tumor-bearing rats are higher than those observed for (64)Cu-di-acetyl-bis (N(4)-methylthiosemicarbazone) and approach those of beta-D-(125)I-iodinated azomycin galactopyranoside, the optimal hypoxia marker of the azomycin-nucleoside class. CONCLUSION: These data suggest that some azomycin-cyclams exhibit good hypoxia-marking potential to tumor cells in vitro and to animal tumors of known RHF. Both PET and SPECT could be used to image tumor hypoxia with markers labeled with (64)Cu and (67)Cu, respectively.

Animals↗

[Sweetness potency of saccharin and cyclamate in hot drinks].

The sweetness potency of sweeteners depends on temperature. At 50 degrees C the 2.4-fold concentration of saccharin and the 1.3-fold of cyclamate respectively is needed to produce the same sweetness (as related to sucrose) as in solutions at 20 degrees C. As well as in water the sweetening power decreases in chinese tea with increasing temperature. Only in case of cyclamate solutions of high sweetness this effect is diminished. In the mathematical description of the relation between stimulus and perception the decrease of the relative sweetness observed can be expressed by a comformable decrease of the concentration coefficient. The effect of temperature on the perception of sweetness can be explained by the Arrhenius' conception. The critical increments are 23 kJ/mol for saccharin and 8 kJ/mol for both cyclamate and fructose.

Cyclamates↗

[Sensitive and selective HPLC methods with prechromatographic derivatization for the determination of cyclamate in foods].

A sensitive and selective high pressure liquid chromatography (HPLC) procedure for the determination of sodium cyclamate in juices and preserves is presented. The method depends on the oxidation of cyclamate to cyclohexylamine, which then is converted prechromatographically into a fluorescent derivative. It is analyzed by HPLC on a C18:reversed-phase column and determined with fluorescence detection (excitation at 350 nm, emission at 440-650 nm). The detection limit of sodium cyclamate was 0.5-5 mg/kg, depending on the nature and dilution of the samples. The relative standard deviations thus obtained were +/- 1.0 to +/- 2.6%. The average recovery was 90%.

Beverages↗

[Determination of cyclamate in complex matrix using HPLC after column derivatization with 4-fluoro-7-nitrobenzofurazan].

A method for the analysis of cyclamate in complex foodstuffs has been developed. This method is applicable in strongly coloured and protein-rich foodstuffs. The quantitative determination depends on oxidation of cyclamate to cyclohexylamine and derivatisation with 4-fluoro-7-nitrobenzofuran (NBD-F). The derivatives are analysed by HPLC on a C18: reversed-phase column, their minimal stability being 12 h. There are two possible methods of detection: (a) absorbance at 485 nm and (b) fluorescence with excitation at 485 nm and emission at 530 nm. The detection limit of cyclamate is 5 mg/kg foodstuff, with fluorescence detection 0.4 mg/kg. The recoveries are in the range of 88% to 104%.

4-Chloro-7-nitrobenzofurazan↗

Quantification of cyclamate and cyclohexylamine in urine samples using high-performance liquid chromatography with trinitrobenzenesulfonic acid pre-column derivatization.

An HPLC isocratic method with pre-column derivatization and UV detection for the quantification of cyclamate and cyclohexylamine in urine samples is described. The method requires very little sample preparation. Free cyclohexylamine is analysed in a first run and subsequently cyclamate is analysed as cyclohexylamine, after the simple process of oxidation of the sample by means of hydrogen peroxide. Cycloheptylamine is used as internal standard. Trinitrobenzenesulfonic acid (TNBS) appears to be a good reagent for the pre-column derivatization. The time per run is 15 min; the coefficients of variation of the assays range from 1.1 to 5.5%; the limits of detection are 0.09 and 0.11 ppm for cyclohexylamine and cyclamate anion, respectively. The system described has always performed efficiently, with a high degree of stability, in daily routine work.

Chromatography, High Pressure Liquid↗

Saccharin and cyclamate inhibit binding of epidermal growth factor.

The binding of 125I-labeled mouse epidermal growth factor (EGF) to 18 cell lines, including HeLa (human carcinoma), MDCK (dog kidney cells), HTC (rat hepatoma), K22 (rat liver), HF (human foreskin), GM17 (human skin fibroblasts), XP (human xeroderma pigmentosum fibroblasts), and 3T3-L1 (mouse fibroblasts), was inhibited by saccharin and cyclamate. The human cells were more sensitive to inhibition by these sweeteners than mouse or rat cells. EGF at doses far above the physiological levels reversed the inhibition in rodent cells but not in HeLa cells. In HeLa cells, the doses of saccharin and cyclamate needed for 50% inhibition were 3.5 and 9.3 mg/ml, respectively. Glucose, 2-deoxyglucose, sucrose, and xylitol did not inhibit EGF binding. Previous studies have shown that phorbol esters, strongly potent tumor promoters, also inhibit EGF binding to tissue culture cells. To explain the EGF binding inhibition by such greatly dissimilar molecules as phorbol esters, saccharin, and cyclamate, it is suggested that they operate through the activation of a hormone response control unit.

Animals↗

Effects of cyclamate calcium on the immune response in rabbits.

To determine the effect of cyclamate calcium on the humoral immune response in rabbits, one group was fed a 3% and another a 5% water solution of cyclamate calcium. A third group served as controls. After 150 days, the animals were tested for their ability to respond immunologically to bovine serum albumin (BSA). Other aspects of immunity investigated were the presence or absence of neoplasia of the urinary bladder, spleen, thymus, and lymph nodes, the number of white and red blood cells, and cyclamate conversion and excretion in the urine. The results indicated that the 5% group had a delayed and suppressed response to BSA. No neoplasia was detected. This group had fewer red cells and excreted increased concentrations of cyclohexylamine in the urine.

Animal Feed↗

Intake of saccharin, aspartame, acesulfame K and cyclamate in Italian teenagers: present levels and projections.

The intake of saccharin, aspartame, acesulfame K and cyclamate was assessed in 212 Italian teenagers aged 13-19 in 1996. Total daily intake of intense sweeteners was assessed on the basis of dietary records (14 consecutive days). The sweetener content of sugar-free products (soft drinks, candies, chewing gums, yoghurts, jam and table-top sweeteners) was provided by manufacturers. Sugar-free products were consumed by 77% of the subjects. Mean daily intake among consumers was 0.24 mg/kg body weight (bw) for cyclamate (13 subjects), 0.21 mg/kg bw for saccharin (9 subjects), 0.03 mg/kg bw for aspartame (162 subjects), and 0.02 mg/kg bw for acesulfame K (56 subjects). No subject exceeded the ADI (Acceptable Daily Intake) of an intense sweetener. Projections based on the present levels of use of intense sweeteners in sugar-free products and on the dietary pattern observed in the sample suggest that approaching the ADI could be possible only if subjects with high intakes of both soft drinks and table-top sugar substituted these items with respectively sugar-free beverages and table-top sweeteners containing either saccharin or cyclamate.

Adolescent↗

[35S]Cyclamate metabolism: incorporation of 35S into proteins of intestinal bacteria in vitro and production of volatile 35S-containing compounds.

1. A washed whole-cell suspension of bacteria prepared from the faeces of rats regularly fed oral cyclamate incorporated 35S into bacterial protein when challenged with [35s]cyclamate. Control preparations showed low-level incorporation of label. 2. Radioactivity was also accounted for as volatile 35S-containing compounds (s), soluble in sodium hydroxide. 3. Addition of cysteine to incubation mixtures inhibited incorporation of 35S into proteins. 4. The results suggest that the bacterial conversion of cyclamate to the suspected bladder carcinogen, cyclohexylamine, is controlled by the prevailing sulphur metabolism of the intestinal bacteria.

Animals↗