Physiological mechanisms mediating aspartame-induced satiety

Aspartame has been previously shown to increase satiety. This study aimed to investigate a possible role for the satiety hormones cholecystokinin (CCK) and glucagon-like peptide-1 (GLP-1) in this effect. The effects of the constituents of aspartame, phenylalanine and aspartic acid, were also examined. Six subjects consumed an encapsulated preload consisting of either 400 mg aspartame, 176 mg aspartic acid + 224 mg phenylalanine, or 400 mg corn flour (control), with 1.5 g paracetamol dissolved in 450 ml water to measure gastric emptying. A 1983-kJ liquid meal was consumed 60 min later. Plasma CCK, GLP-1, glucose-dependent insulinotropic polypeptide (GIP), glucose, and insulin were measured over 0-120 min. Gastric emptying was measured from 0 to 60 min. Plasma GLP-1 concentrations decreased following the liquid meal (60-120 min) after both the aspartame and amino acids preloads (control, 2096.9 pmol/l min; aspartame, 536.6 pmol/l min; amino acids, 861.8 pmol/l min; incremental area under the curve [AUC] 60-120 min, P<.05). Desire to cat was reduced from 60 to 120 min following the amino acids preload (control, -337.1 mm min; aspartame, -505.4 mm min; amino acids, -1497.1 mm min; incremental AUC 60-120 min, P<.05). However, gastric emptying rates, plasma CCK, GIP, insulin, and glucose concentrations were unaffected. There was a correlation between the increase in plasma phenylalanine and decrease in desire to eat after the liquid meal following the constituent amino acids (r = -.9774, P=.004). In conclusion, it is unlikely that aspartame increases satiety via CCK- or GLP-1-mediated mechanisms, but small changes in circulating phenylalanine concentrations may influence appetite. (C) 2003 Elsevier Science Inc. All rights reserved.

Measurement of the relative sweetness of stevia extract, aspartame and cyclamate/saccharin blend as compared to sucrose at different concentrations

Special diets are used to mitigate many human diseases. When these diets require changes in carbohydrate content, then sweetness becomes an important characteristic. The range of low-calorie sweeteners available to the food industry is expanding. It is essential to have an exact knowledge of the relative sweetness of various sweeteners in relation to different sucrose concentrations. The objective of this study was to determine the variation on the relative sweetness of aspartame (APM), stevia [Stevia rebaudiana (Bert.) Bertoni] leaf extract (SrB) and the mixture cyclamate/saccharin - two parts of cyclamate and one part of saccharin - (C/S) with the increase in their concentrations, and in neutral and acid pH in equi-sweet concentration to 10% sucrose, using magnitude estimation. Sweetness equivalence of SrB in relation to sucrose concentrations of 20% or higher and of APM and C/S to sucrose concentrations of 40% or higher could not be determined, because a bitter taste predominated. The potency of all sweeteners decreased as the level of sweetner increased. In equi-sweet concentration of sucrose at 10%, with pH 7.0 and pH 3.0, the potency was practically the same for all sweeteners evaluated.

Synthesis, characterization and antimycobacterial activity of Ag(I)-aspartame, Ag(I)-saccharin and Ag(I)-cyclamate complexes

The present work describes the synthesis and antimycobacterial activity of three Ag(I)-complexes with the sweeteners aspartame, saccharin, and cyclamate as ligands, with the aim of finding new candidate substances for fighting tuberculosis and other mycobacterial infections. The minimal inhibitory concentration of these three complexes was investigated in order to determine their in-vitro antimycobacterial activity against Mycobacterium tuberculosis, Mycobacterium avium, Mycobacterium intracellulare, Mycobacterium malmoense, and Mycobacterium kansasii. The MIC values were determined using the Microplate Alamar Blue Assay. The best MIC values found for the complexes were 9.75 mu M for Ag(l)-aspartame against M. kansasii and 15.7 mu M for Ag(I)-cyclamate against M. tuberculosis.

Silver nanoparticles synthesized by thermal reduction of a silver(I)-aspartame complex in inert atmosphere

Synthesis of silver nanoparticles by thermal treatment of a silver-aspartarne complex under inert atmosphere is described. Spherical metallic silver naroparticles with average diameter of 5 +/-2 nm were obtained by thermal treatment of the complex [Ag(C14H17N2O5)] 1/2H(2)O at 185 degrees C. Thermogravimetric and infrared analysis of the product show the occurrence of an ester bond cleavage of the aspartame ligand followed by rearrangement and release of a molecule of formaldehyde (H2CO), which is transformed in two strong reducing molecules, H-2 and CO. For silver reduction, the presence of the formaldehyde molecules seems to be the key process for the metallic nanoparticles fort-nation. The maintenance of the ligand crystalline structure, with the exception of the ester group loss, was noted as essential for nanoparticles formation and size control. The ligand crystalline structure was completely lost at 200 degrees C and particle growth and coalescence were observed above 250 degrees C. (C) 2005 Elsevier B.V. All rights reserved.

Synthesis, structure and redox properties of an unexpected trinuclear copper(II) complex with aspartame: [Cu(apm)(2)Cu(mu-N,O : O '-apm)(2)(H2O)Cu(apm)(2)(H2O)]center dot 5H(2)O

Structural, magnetic and spectroscopic data of a new trinuclear copper(II) complex with the ligand aspartame (apm) are described. [Cu(apm)(2)CU(mu-N,O:O'-apm)(2)(H2O)Cu(apm)(2)(H2O)]-5H(2)O crystallizes in the triclinic system, space group P1 (#1) with a = 7.3300(1) angstrom, b = 15.6840(1) angstrom, c = 21.5280(1) angstrom, alpha = 93.02(1)degrees, beta = 93.21 (1)degrees, gamma = 92.66(1)degrees and Z = 1. Aspartame coordinates to Cu(II) through the carboxylate and beta-amino groups. The carboxylate groups of the two central ligands act as bidentate bridges in a syn-anti conformation while the carboxylate groups of the four peripheral ligands are monodentate in a syn conformation. The central copper ion is in a distorted square pyramidal geometry with the apical position being occupied by one oxygen atom of the water molecule. The two terminal copper(II) atoms are coordinated to the ligands in the same position but their coordination sphere differs from each other due to the fact that one copper atom has a water molecule in an apical position leading to an octahedral coordination sphere while the other copper atom is exclusively coordinated to aspartame ligands forming a distorted square pyramidal coordination sphere. Thermal analysis is consistent with the X-ray structure. EPR spectra and CV curves indicate a rupture of the trinuclear framework when this complex is dissolved in ethanol or DMF, forming a mononuclear species, with a tetragonal structure. (c) 2005 Elsevier B.V. All rights reserved.

X-ray powder diffraction analysis of a silver(I)-aspartame complex

Synchrotron X-ray powder diffraction (XRPD) data were collected for the silver(I)-aspartame complex [Ag(C14H17N2O5)]center dot 1/2 H2O. The complex was obtained from a stoichiometric mixture of aspartame (3-amino-N-(alpha-carboxyphenethyl)-succinamic acid N-methyl ester, C14H18N2O5), Na2CO3, and AgNO3. Indexing using Crysfire and Chekcell proposed an orthorhombic unit cell with space group P222(1). The lattice parameters are a = 12.4750(1) angstrom, b = 21.60614(14) angstrom, and c = 4.88888(9) angstrom. (C) 2006 International Centre for Diffraction Data.

Composto de prata com aspartame, processo de preparação do composto e agente bactericida obtido a partir do composto

Especialmente desenvolvido contra as micobactérias. O dito composto apresentando a composição e ser preparado pela reação entre Aspartame e nitrato de prata em meio neutro, possuindo a atividade bactericida contra as micobactérias a saber: Mycobacterium tuberculosis, Mycobacterium avium, Mycobacterium intracellulare, Mycobacterium malmoense e Mycobacterium kansasii.

Effects of Sweetness and Energy in Drinks on Food Intake Following Exercise

Exercise is known to cause physiological changes that could affect the impact of nutrients on appetite control. This study was designed to assess the effect of drinks containing either sucrose or high-intensity sweeteners on food intake following exercise. Using a repeated-measures design, three drink conditions were employed: plain water (W), a low-energy drink sweetened with artificial sweeteners aspartame and acesulfame-K (L), and a high-energy, sucrose-sweetened drink (H). Following a period of challenging exercise (70% VO2 max for 50 min), subjects consumed freely from a particular drink before being offered a test meal at which energy and nutrient intakes were measured. The degree of pleasantness (palatability) of the drinks was also measured before and after exercise. At the test meal, energy intake following the artificially sweetened (L) drink was significantly greater than after water and the sucrose (H) drinks (p < 0.05). Compared with the artificially sweetened (L) drink, the high-energy (H) drink suppressed intake by approximately the energy contained in the drink itself. However, there was no difference between the water (W) and the sucrose (H) drink on test meal energy intake. When the net effects were compared (i.e., drink + test meal energy intake), total energy intake was significantly lower after the water (W) drink compared with the two sweet (L and H) drinks. The exercise period brought about changes in the perceived pleasantness of the water, but had no effect on either of the sweet drinks. The remarkably precise energy compensation demonstrated after the higher energy sucrose drink suggests that exercise may prime the system to respond sensitively to nutritional manipulations. The results may also have implications for the effect on short-term appetite control of different types of drinks used to quench thirst during and after exercise.

A glucose-centric perspective of hyperglycemia

Digestion of food in the intestines converts the compacted storage carbohydrates, starch and glycogen, to glucose. After each meal, a flux of glucose (>200 g) passes through the blood pool (4-6 g) in a short period of 2 h, keeping its concentration ideally in the range of 80-120 mg/100 mL. Tissue-specific glucose transporters (GLUTs) aid in the distribution of glucose to all tissues. The balance glucose after meeting the immediate energy needs is converted into glycogen and stored in liver (up to 100 g) and skeletal muscle (up to 300 g) for later use. High blood glucose gives the signal for increased release of insulin from pancreas. Insulin binds to insulin receptor on the plasma membrane and activates its autophosphorylation. This initiates the post-insulin-receptor signal cascade that accelerates synthesis of glycogen and triglyceride. Parallel control by phos-dephos and redox regulation of proteins exists for some of these steps. A major action of insulin is to inhibit gluconeogensis in the liver decreasing glucose output into blood. Cases with failed control of blood glucose have alarmingly increased since 1960 coinciding with changed life-styles and large scale food processing. Many of these turned out to be resistant to insulin, usually accompanied by dysfunctional glycogen storage. Glucose has an extended stay in blood at 8 mM and above and then indiscriminately adds on to surface protein-amino groups. Fructose in common sugar is 10-fold more active. This random glycation process interferes with the functions of many proteins (e.g., hemoglobin, eye lens proteins) and causes progressive damage to heart, kidneys, eyes and nerves. Some compounds are known to act as insulin mimics. Vanadium-peroxide complexes act at post-receptor level but are toxic. The fungus-derived 2,5-dihydroxybenzoquinone derivative is the first one known to act on the insulin receptor. The safe herbal products in use for centuries for glucose control have multiple active principles and targets. Some are effective in slowing formation of glucose in intestines by inhibiting alpha-glucosidases (e.g., salacia/saptarangi). Knowledge gained from French lilac on active guanidine group helped developing Metformin (1,1-dimethylbiguanide) one of the popular drugs in use. One strategy of keeping sugar content in diets in check is to use artificial sweeteners with no calories, no glucose or fructose and no effect on blood glucose (e.g., steviol, erythrytol). However, the three commonly used non-caloric artificial sweetener's, saccharin, sucralose and aspartame later developed glucose intolerance, the very condition they are expected to evade. Ideal way of keeping blood glucose under 6 mM and HbAlc, the glycation marker of hemoglobin, under 7% in blood is to correct the defects in signals that allow glucose flow into glycogen, still a difficult task with drugs and diets.

Sensory profiles and consumer acceptability of a range of sugar-reduced products on the UK market

Current UK intake of non-milk extrinsic sugars (NMES) is above recommendations. Reducing the sugar content of processed high sugar foods through reformulation is one option for reducing consumption of NMES at a population level. However, reformulation can alter the sensory attributes of food products and influence consumer liking. This study evaluated consumer acceptance of a selection of products that are commercially-available in the UK; these included regular and sugar-reduced baked beans, strawberry jam, milk chocolate, cola and cranberry & raspberry juice. Sweeteners were present in the reformulated chocolate (maltitol), cola (aspartame and acesulfame-K) and juice (sucralose) samples. Healthy, non-smoking consumers (n = 116; 55 men, 61 women, age: 33 ± 9 years; BMI: 25.7 ± 4.6 kg/m2) rated the products for overall liking and on liking of appearance, flavor and texture using a nine-point hedonic scale. There were significant differences between standard and reduced sugar products in consumers’ overall liking and on liking of each modality (appearance, flavor and texture; all P < 0.0001). For overall liking, only the regular beans and cola were significantly more liked than their reformulated counterparts (P < 0.0001). Cluster analysis identified three consumer clusters that were representative of different patterns of consumer liking. For the largest cluster (cluster 3: 45%), there was a significant difference in mean liking scores across all products, except jam. Differences in liking were predominantly driven by sweet taste in 2 out of 3 clusters. The current research has demonstrated that a high proportion of consumers prefer conventional products over sugar-reduced products across a wide range of product types (45%) or across selected products (27%), when tasted unbranded, and so there is room for further optimization of commercial reduced sugar products that were evaluated in the current study. Future work should evaluate strategies to facilitate compliance to dietary recommendations on NMES and free sugars, such as the impact of sugar-reduced food exposure on their acceptance.

Caffeine as a flavor additive in soft-drinks

Over 60% of soft-drinks sold in the United States contain caffeine, a mildly addictive psycho-active chemical, as a flavor additive. Using sweeteners as controls, we assessed whether caffeine has flavor activity in a cola soft-drink. A forced-choice triangle discrimination methodology was used to determine detection thresholds of caffeine in sweeteners and a cola beverage. The subjects (n=30, 28 female, 23±4 years old) were trained tasters and completed over 1600 discrimination tests during the study. The mean detection thresholds for caffeine in the sweet solutions were: 0.333±0.1 mM sucrose; 0.467±0.29 mM aspartame; 0.462±0.3 mM sucralose, well below the concentration in common cola beverages (0.55–0.67 mM). A fixed concentration of caffeine, corresponding to the concentration of caffeine in a common cola beverage (0.67 mM) was added to the sweeteners and a non-caffeinated cola beverage. Subjects could distinguish between caffeinated and non-caffeinated sweeteners (p<0.001), but all subjects failed to distinguish between caffeinated and non-caffeinated cola beverage (p=1.0). Caffeine has no flavor activity in soft-drinks yet will induce a physiologic and psychologic desire to consume the drink.

Oral zinc sulfate solutions inhibit sweet taste perception

We investigated the ability of zinc sulfate (5, 25, 50 mM) to inhibit the sweetness of 12 chemically diverse sweeteners, which were all intensity matched to 300 mM sucrose [800 mM glucose, 475 mM fructose, 3.25 mM aspartame, 3.5 mM saccharin, 12 mM sodium cyclamate, 14 mM acesulfame-K, 1.04 M sorbitol, 0.629 mM sucralose, 0.375 mM neohesperidin dihydrochalcone (NHDC), 1.5 mM stevioside and 0.0163 mM thaumatin]. Zinc sulfate inhibited the sweetness of most compounds in a concentration dependent manner, peaking with 80% inhibition by 50 mM. Curiously, zinc sulfate never inhibited the sweetness of Na-cyclamate. This suggests that Na-cyclamate may access a sweet taste mechanism that is different from the other sweeteners, which were inhibited uniformly (except thaumatin) at every concentration of zinc sulfate. We hypothesize that this set of compounds either accesses a single receptor or multiple receptors that are inhibited equally by zinc sulfate at each concentration.

Anti-amnesic effect of enzyme extracted stevioside from Stevia rebaudiana

The increasing consumption of sucrose has resulted in several nutritional and medicinal problems, including obesity. There is an alarming rise in the prevalence of obesity, type 2 diabetes mellitus, and metabolic syndrome in children and adults around the world, partly related to increasing availability of energy-dense, high-calorie foods, and perhaps to increased consumption of sugar and particularly fructose sweetened beverages. Therefore, low calorie sweeteners are urgently required to substitute table sugar.

Stevioside, a diterpene glycoside, is well known for its intense sweetness and is used as a non-caloric sweetener. Its potential widespread use requires an easy and effective extraction method. Enzymatic extraction of stevioside from Stevia rebaudiana leaves with cellulase, pectinase and hemicellulase using various parameters such as concentration of enzyme, incubation time and temperature was optimized. The extraction conditions were further optimized using response surface methodology (RSM). Under the optimized conditions, the experimental values were in close agreement with predicted model and resulted in a three times yield enhancement of stevioside.

Various studies have revealed that in addition to sweetening nature of stevisoide, it exerts beneficial effects including antihypertensive, anti-hyperglycemic, anti-human rotavirus, antioxidant, anti-inflammatory and antitumor actions. Its anti-amnesic potential remains to be explored, therefore the present study has been undertaken to investigate the beneficial effect of stevioside in memory deficit of rats employing scopolamine induced amnesia as an animal model.

Significance: Stevia is gaining significance in different parts of the world and is expected to develop into a major source of high potency sweetener for the growing natural food market. There is a strong possibility that Stevia sweeteners could replace aspartame in some diet variants. In addition, Stevia is expected to be used as a part substitute for sugar and also used in combination with other artificial sweeteners in the emerging phase of life cycle.