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PubMed1995

[The psychophysics of sweet taste. 7. New determination of sweet taste parameters of acesulfame, aspartame, cyclamate, saccharin, glucose and sorbitol].

By means of a new method (double staircase) concentration pairs of equal intensity for the sweet compounds acesulfame-K, aspartame, cyclamate-Na, saccharine-Na, dextrose and glucitol were determined with sucrose on 6 or 7 equidistant scaled levels, respectively, with 4 repetitions. The parameters maximal intensity Rm, the concentration coefficient b and the mean Rm/b, respectively, are calculated for each substance from the known parameters for sucrose using the exponential function R = Rm(1-e-bS/Rm), which describes the sweetness intensity R in dependence of the concentration S. For exact determination of the maximal intensity the upper concentration level was fixed at very high degree. Additionally, the relative sweetness of each concentration level of each substance is calculated. In all cases the exponential function is valid without limitation. The statistical parameters are homogenous and are laying within the applied staircase method. Systematical deviations could not be found.

Adult↗
PubMed1988

[A new HPLC procedure for cyclamate in food with pre-chromatographic derivatization].

A high-pressure liquid chromatography (HPLC) procedure for the detection of cyclamate in liquid and solid samples is presented, which depends on oxidation and the reaction of cyclohexylamine with o-phthaldialdehyde to form a condensation product. The results of the HPLC analysis, using an RP-C 18 separation system with UV detection at 242 nm are reported. Contents, from 2 to 400 mg/l, can be detected in less than 2 h (HPLC analysis within 20 min) with relative standard deviations of 4%. Only for cucumber infusions were incomplete recoveries of 68% obtained.

Chromatography, High Pressure Liquid↗
PubMed1978

Correlation of chemical structure and taste in the cyclamate series and the steric nature of the chemoreceptor site.

The requirements of compounds in the cyclamate series for sweet taste stimulation are: synclinal conformation between NH and SO in the aminosulphonate group, length less than 0.7 nm of the group on the nitrogen, and hydrophobic character of the latter group. A hypothetical receptor site for these compounds should have a spatial barrier at a distance of about 0.7 nm from the nitrogen interaction point with the receptor site, and a hydrophobic interaction area between the nitrogen interaction point and the barrier.

Chemical Phenomena↗
PubMed1985

Acesulfame K, cyclamate and saccharin inhibit the anaerobic fermentation of glucose by intestinal bacteria.

The caecal microflora of Cara rats was incubated in the pH stat with glucose under anaerobic conditions, and the acid production was measured. In the presence of the sweeteners Acesulfame K, Cyclamate and Saccharin, inhibition of the fermentation of glucose was observed with ED50 values of 260, 251, and 140 mM, respectively. The nutritional relevance of these observations is probably slight; an interpretation in terms of bacterial physiology leads to the proposal that the sweeteners may act on glucose transport systems at the bacterial cytomembrane.

Anaerobiosis↗
PubMed1983

Fatty-acid conjugation with cyclamate metabolites as a possible mechanism for ultimate retention.

In an in vitro rat-liver microsomal system fortified with coenzyme. A palmitic acid was found to conjugate at the nitrogen moiety of the cyclamate metabolite cyclohexylamine (CHA) and at both the nitrogen and oxygen moieties of its metabolite N-cyclohexylhydroxylamine (CHHA). The fatty acid was preferentially conjugated at or preferentially retained to the nitrogen moiety of CHHA. Stearic acid was also shown to conjugate with CHA. Amines may thus be another class of compounds that, like hydroxylated compounds, are retained in vivo as fatty-acid conjugates in lipid-containing tissues of animals.

Animals↗
PubMed1988

Myocardial effects of calcium cyclamate in the BIO F1D Alexander Syrian golden hamster.

In a subchronic 90-day oral toxicity study, 5 groups (20 males, 20 females each) of F2-descendants of BIO F1D Alexander hamsters received 0, 275, 550, 1,100 and 2,200 mg/kg b.w./day doses, respectively, of calcium cyclamate in the drinking water. These doses caused no adverse health effects in any treated animal and the multifocal myocardial calcifications, detectable at a 100% incidence in the male and female control hamsters (20 males, 20 females), were not exacerbated by the sweetener. Instead, the myocardial lesions exhibited a striking negative dose-response relationship with a 0% incidence in the males and a 5% incidence in the female hamsters of the highest dose group.

Animals↗
PubMed1992

Assessment of the carcinogenicity of the nonnutritive sweetener cyclamate.

The weight of the evidence from metabolic studies, short-term tests, animal bioassays, and epidemiological studies indicates that cyclamate (CHS) is not carcinogenic by itself; however, there is evidence from in vitro and in vivo studies in animals that implies it may have cancer-promoting or cocarcinogenic activity. Epidemiological studies indicate that the use of nonnutritive sweeteners (CHS and saccharin) has not resulted in a measurable overall increase in the risk of bladder cancer in individuals who have ever used these products. No epidemiological information exists on the possible associations of these sweeteners and cancers other than those of the urinary tract. It is recommended that (1) no further studies on the metabolism of CHS to evaluate its carcinogenicity are required since no potentially hazardous metabolites have been appreciably detected in humans; (2) no further animal bioassays to test for the carcinogenicity of CHS by itself are necessary; (3) the studies in rodents that suggest a promotional or cocarcinogenic effect of CHS should be repeated because they cannot be ruled out; (4) because the significance to human health of a positive outcome of such studies is uncertain, additional research aimed at understanding the predictive value for human health of such results and more generic studies to develop well-validated systems that can be relied on in the assessment of cancer-promoting agents are recommended; (5) in populations where CHS continues to be used, epidemiological monitoring should be continued to determine whether there is an increased risk of cancer in humans who are heavy or long-term users or for those observed long after first exposure. In such monitoring, other cancer sites--in addition to the bladder--should be considered.

Animals↗
PubMed2003

Effects of a saccharin and cyclamate mixture on rat embryos.

Sodium saccharin (NaS) and calcium cyclamate (CaC) are artificial sweeteners widely used in food and drink. To evaluate their toxicological effects on preimplantation mammalian embryos, pregnant rats were gavaged with 1.65 mg NaS/kg bw + 3.85 mg CaC/kg bw (DI) or 6.6 mg NaS/kg bw + 15.4 mg CaC/kg bw (D2) on days 1, 2, 3 and 4 of pregnancy (positive vaginal smear = day 1). The female rats were killed on day 5 of the pregnancy (GD 5), maternal organs weighed, and the blastocysts collected, counted and evaluated for gross morphology, cell number and mitotic index. There was no alteration in maternal organ weights, but there was an increase of the cell number/embryo in the dams treated with that NaS + CaC mixtures (D1 = 37.20 +/- 7.96; D2 = 37.26 +/- 10.90) compared to control group (32.24 +/- 6.73). Embryos whose dams were exposed to NaS + CaC may have adapted for implantation into the uterus but more studies are needed to demonstrate this mechanism of action.

Administration, Oral↗
PubMedDate not supplied

Spectrophotometric determination of cyclamate in soft drinks and desserts: complementary collaborative study.

Fifteen official food control laboratories participated in a collaborative study of a spectrophotometric method to determine cyclamate in a soft drink and a dessert at concentrations of 90-311 mg/L and 202-526 mg/kg, respectively, with blind duplicates and a blank. Average recovery from the soft drink was 97.5%, and from the dessert, 98.6%. Reproducibility relative standard deviations were 4.7-6.5% and 6.9-8.5%, respectively. The outlier percentage was 5.5%. This study complements an earlier work by leading Nordic food laboratories and was designed according to the latest recommendations. The results of this study were compared with those of the earlier collaborative study and with general collaborative results obtained by AOAC.

Beverages↗
PubMed1982

Inhibition of iodinated nerve growth factor binding by the suspected tumor promoters saccharin and cyclamate.

The strong correlation between tumor-promoting activity and the capacity to inhibit nerve growth factor-induced neurite outgrowth for a number of compounds prompted studies on the suspected bladder tumor promoters saccharin and cyclamate. These artificial sweeteners reversibly inhibited neurite outgrowth and binding of [125I]nerve growth factor in embryonic chick sensory ganglia cells. Curves showing the dose-dependent inhibition of response and the dose-dependent inhibition of binding to high affinity sites were closely parallel. The inhibition appeared to be due to a reduction in the affinity rather than to a change in the number of binding sites, as indicated by the extent of reduction in the association rate. These results suggest that alteration of cellular differentiation by tumor promoters may result from interactions with receptor systems that regulate specialized cell functions.

Animals↗
PubMed1980

Absence of carcinogenic response to cyclamate and saccharin in Sprague-Dawley rats after transplacental application.

Female Sprague-Dawley rats were treated by gavage either with cyclamate or saccharin at doses of 5, 1 and 0.2 g/kg body weight on days 14, 17 and 20 of pregnancy. The offspring were observed throughout their lives. No carcinogenic activity of the exposure in utero to the test compounds was observed. The results of this study support the conclusion that application of the tested artificial sweeteners during pregnancy is not an important risk factor for any type of cancer in Sprague-Dawley rats.

Animals↗
PubMed2001

A technetium-99m-labelled cyclam acid porphyrin (CAP) for tumour imaging.

A new water-soluble cyclam acid porphyrin (CAP), 5,10,15,20-tetrakis [4-[4',8',11'-tris(carboxymethyl)-1'-(1',4',8',11'-tetraazacyclotetradecane)amidomethyleneoxy]phenyl] porphyrin has been synthesised, characterised and labelled with 99mTc. In vivo distribution studies were performed in C6-gliomas and N-nitroso-N-methylurea (NMU) induced mammary tumour bearing rats and scintiimages were obtained at 5 h post-administration of the labelled ligand using gamma camera computer system. Tumour to muscle (T/M) ratios were determined and compared with currently available tumour seeking radiopharmaceuticals such as 99mTc(V)-DMSA, 99mTc-Citrate and 201TlCl. In the case of NMU induced mammary tumour rats the ratios were 6.93, 1.97, 5.30 and 3.29; while in the case of C6-gliomas the ratios were 5.58, 2.18, 3.96 and 3.02 for 99mTc-CAP, 99mTc(V)-DMSA, 99mTc-Citrate and 203TlCl, respectively.

Animals↗
PubMed2002

Crown ether appended cyclam receptors for cationic guests.

A series of crown ether appended macrocyclic amines has been prepared comprising benzo-12-crown-4, benzo-15-crown-5, or benzo-18-crown-6 attached to a diamino-substituted cyclam. The Co(III) complexes of these three receptors have been prepared and characterized spectroscopically and structurally. Crystal structures of each receptor in complex with an alkali metal ion and structures of the benzo-12-crown-4 and benzo-15-crown-5-receptors without guest ions are reported. 2D NMR and molecular mechanics modeling have been used to examine conformational variations upon guest ion complexation. Addition of cations to these receptors results in an appreciable anodic shift in the Co(III/II) redox potential, even in aqueous solution, but little cation selectivity is observed. Evidence for complex formation has been corroborated by (23)Na and (7)Li NMR spectroscopy and electrospray mass spectrometry.

Journal Article↗
PubMed2002

Solvation largely accounts for the effect of N-alkylation on the properties of nickel(II/I) and chromium(III/II) cyclam complexes.

The source of the effect of N-alkylation on the redox properties of Ni(II/I) and Cr(III/II) cyclam complexes has been investigated using DFT calculations. The structures of the anhydrous and hydrated complexes were optimized in the gas phase, and single point calculations were performed in a polarized continuum. The main results are the following: the decrease in outer sphere solvation upon N-alkylation is the major source of the relative stabilization of the lower oxidation state complexes by the tertiary amine ligands; tertiary amine nitrogen donors are stronger sigma-donors than the secondary amines, as predicted from the inductive effect of alkyls; steric strain elongates the metal-nitrogen bonds in the tertiary complexes and decreases the ligand strain energies; and the site of water binding to the complexes differs because of their different electronic structures (i.e., in the Ni complexes, the water molecules bind to the M[bond]N[bond]H sites, whereas in the Cr complexes they bind to the central metal cation). Outer sphere hydrogen bonding of water to the ligands in the coordination sphere lowers the ionization potentials by charge delocalization.

Journal Article↗
PubMed2005

Synthesis and luminescence properties of Cr(III) complexes with cyclam-type ligands having pendant chromophores, trans-[Cr(L)Cl(2)]Cl.

The synthesis and spectroscopic properties of new cyclam-type ligands 5,7-dimethyl-6-R-1,4,8,11-tetraazacyclotetradecane (L), where R is a pendant chromophore such as an anthracene derivative, are reported. These ligands were prepared according to a nickel(II) template procedure, and the X-ray crystal structures of several Ni(II) intermediates are described. Reaction of the free base ligands L with CrCl(3)x3THF resulted in facile formation of trans-[Cr(L)Cl(2)]Cl complexes, and the structures and spectroscopic characterizations of these complexes are also described. Examination of the photophysical properties of trans-[Cr(L)Cl(2)]Cl solutions at 77 K demonstrated the emission spectra to be dominated by phosphorescence from the ligand field doublet of the chromium(III) center. This also applies to the Cr(III) complex trans-[Cr(mac)Cl(2)]Cl, where mac is the anthracene derivative 5,7-dimethyl-6-anthracenylcyclam. Excitation into the pi-pi(*) states of the anthracene leads to marked quenching of the fluorescence from this chromophore and sensitized phosphorescence from the metal-centered doublet state.

Chromium↗
PubMed2006

Synthesis, characterization, and solution properties of a novel cross-bridged cyclam manganese(IV) complex having two terminal hydroxo ligands.

A novel monomeric tetravalent manganese complex with the cross-bridged cyclam ligand 4,11-dimethyl-1,4,8,11-tetraazabicyclo[6.6.2]hexadecane (Me2EBC), [Mn(IV)(Me2EBC)(OH)2](PF6)2, was synthesized by oxidation of Mn(II)(Me2EBC)Cl2 with H2O2 in the presence of NH4PF6)in aqueous solution. The X-ray crystal structure determination of this manganese(IV) compound revealed that it contains two rare terminal hydroxo ligands. EPR studies in dry acetonitrile at 77 K show two broad resonances at g = 1.96 and 3.41, indicating that the manganese(IV) exists as a high-spin d3 species. Resonance Raman (rR) spectra of this manganese(IV) species reveal that the dihydroxy moiety, Mn(IV)(OH)2, is also the dominant species in aqueous solution (pH < 7). pH titration provides two pK(a) values, 6.86(4) and 10.0(1), associated with stepwise removal of the last two oxygen-bound protons from [Mn(IV)(Me2EBC)(OH)2](2+). The cyclic voltammetry of this manganese(IV) complex in dry acetonitrile at 298 K demonstrates two reversible redox processes at +0.756 and -0.696 V (versus SHE) for the Mn4+/Mn3+ and Mn3+/Mn2+ couples, respectively. This manganese(IV) complex is relatively stable in weak acidic aqueous solution but easily degrades in basic solution to manganese(III) derivatives with an 88 +/- 1% yield.

Journal Article↗
PubMed2002

Radiolabeling and in vivo behavior of copper-64-labeled cross-bridged cyclam ligands.

Macrocyclic chelators and their metal complexes have widespread applications in the biomedical sciences, including radiopharmaceutical chemistry. The use of copper radionuclides in radiopharmaceuticals is increasing. Macrocyclic chelators have been found to have enhanced in vivo stability over acyclic chelators such as ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA). The currently used chelators of choice for labeling copper radionuclides to biological molecules are analogues of TETA (1,4,8,11-tetraazacyclotetradecane-1,4,8,11-tetraacetic acid); however, recent reports have demonstrated evidence of in vivo instability of the radio-Cu(II)-TETA complexes. A new class of structurally reinforced macrocycles, the "cross-bridged" cyclam derivatives, form highly stable complexes with Cu(II) that are resistant to dissociation in strong acid. Here, we evaluate a series of (64)Cu(II) cross-bridged macrocyclic complexes for biological stability and in vivo behavior. The ligands evaluated include the parent ligand, 1,4,8,11-tetraazabicyclo[6.6.2]hexadecane (1), and three 4,11-di-pendant arm derivatives: 4,11-bis(carboxymethyl)-1,4,8,11-tetraazabicyclo[6.6.2]hexadecane (2); 4,11-bis(N,N-diethyl-amidomethyl)-1,4,8,11-tetraazabicyclo[6.6.2]hexadecane (3); and 4,11-bis(amidoethyl)-1,4,8,11-tetraazabicyclo[6.6.2]hexadecane (4). Copper-64 formed complexes with ligands 1-4 in high radiochemical yields. The (64)Cu-2 complex was neutral, while (64)Cu complexes of 1, 3, and 4 were positively charged. All complexes showed no decomposition in rat serum out to 24 h. Biodistribution experiments in Sprague-Dawley rats indicated that (64)Cu-1, -3, and -4 were taken up by the liver and kidney and cleared slowly over 24 h, whereas (64)Cu-2 cleared rapidly from all tissues. The rapid clearance of the (64)Cu-2 complex from the blood and liver, as well as liver metabolism experiments in rats, suggests that it is highly stable in vivo. A bifunctional chelator of 2 is a significant candidate for labeling copper radionuclides to biological molecules for diagnostic imaging and targeted radiotherapy.

Animals↗
PubMed2006

Hg2+-selective OFF-ON and Cu2+-selective ON-OFF type fluoroionophore based upon cyclam.

[structure: see text]. A new cyclam derivative having two different fluorophores of pyrene and NBD subunits was prepared, and its Hg2+- and Cu2+-selective signaling behaviors were investigated. The detection limits for the analysis of Hg2+ and Cu2+ ions were found to be 7.9 x 10(-6) and 2.6 x 10(-7) M in aqueous acetonitrile solution (H2O-CH3CN = 10:90, v/v), respectively. The compound also exhibited a selective Hg2+/Cu2+-induced OFF-ON-OFF type of signaling pattern that can be utilized for the construction of functional supramolecular switching systems.

Journal Article↗