Exploring in vitro, in vivo metabolism of mogroside V and distribution of its metabolites in rats by HPLC-ESI-IT-TOF-MS(n).

Mogroside V, a cucurbitane-type saponin, is not only the major bioactive constituent of traditional Chinese medicine Siraitiae Fructus, but also a widely used sweetener. To clarify its biotransformation process and identify its effective forms in vivo, we studied its metabolism in a human intestinal bacteria incubation system, a rat hepatic 9000g supernatant (S9) incubation system, and rats. Meanwhile, the distribution of mogroside V and its metabolites was also reported firstly. Seventy-seven new metabolites, including 52 oxidation products formed by mono- to tetra- hydroxylation/dehydrogenation, were identified with the aid of HPLC in tandem with ESI ion trap (IT) TOF multistage mass spectrometry (HPLC-ESI-IT-TOF-MS(n)). Specifically, 14 metabolites were identified in human intestinal bacteria incubation system, 4 in hepatic S9 incubation system, 58 in faeces, 29 in urine, 14 in plasma, 34 in heart, 33 in liver, 39 in spleen, 39 in lungs, 42 in kidneys, 45 in stomach, and 51 in small intestine. The metabolic pathways of mogroside V were proposed and the identified metabolic reactions were deglycosylation, hydroxylation, dehydrogenation, isomerization, glucosylation, and methylation. Mogroside V and its metabolites were distributed unevenly in the organs of treated rats. Seven bioactive metabolites of mogroside V were identified, among which mogroside IIE was abundant in heart, liver, spleen and lung, suggesting that it may contribute to the bioactivities of mogroside V. Mogroside V was mainly excreted in urine, whereas its metabolites were mainly excreted in faeces. To our knowledge, this is the first report that a plant constituent can be biotransformed into more than 65 metabolites in vivo. These findings will improve understanding of the in vivo metabolism, distribution, and effective forms of mogroside V and congeneric molecules.

Evaluación de la inocuidad de Stevia rebaudiana Bertoni cultivada en el sureste de México como edulcorante de alimentos / Safety assessment of Stevia rebaudiana Bertoni grown in Southeastern Mexico as food sweetener

Las hojas de Stevia rebaudiana y sus glucósidos recientemente se han comenzado a utilizar de manera importante como edulcorantes. Sin embargo, existen reportes acerca del efecto antihiperglucemiante de extractos y un componente glucósido. El objetivo de este trabajo fue cuantificar los glucósidos de S. rebaudiana, evaluar la citotoxicidad y el efecto de la administración aguda y crónica del extracto sobre la glucemia en modelos animales como en humanos. Los glucósidos de los extracto de las variedades Morita II y Criolla se cuantificaron por HPLC, empleando una columna C18 (250 mm x 4.6 mm y tamaño de partícula de 5µm), con detector UV a 210 nm, fase móvil de acetonitrilo/amortiguador fosfato de sodio 10 mmol/L, pH 2.6 (32:68 v/v). Se realizó un estudio de citotoxicidad en células Vero, una prueba de tolerancia a la glucosa intraperitoneal y ensayo de consumo crónico (4 semanas) en un modelo animal de diabetes y finalmente, se determinó el índice glicémico (I.G) en individuos sanos. El contenido de glucósidos fue mayor en la variedad Morita II aunque la CC50 en ambas es >300 µg/mL. Las áreas bajo la curva de la IPGTT así como la glucosa en ayuno de los animales no fueron significativamente diferentes (p>0.05) y el I.G. del extracto fue 11.11%, lo cual lo clasifica como I.G. bajo. El extracto de S. rebaudiana Morita II es de bajo índice glicémico y, en las dosis evaluadas, no es citotóxico ni posee efecto agudo o crónico sobre la glucemia, lo cual lo hace un edulcorante inocuo (AU)

Stevia rebaudiana leaves and their glycosides have been recently and significantly used so important as sweeteners. However, it has been reported an antihyperglycemic effect of the extract and a glycoside. The aim of this study was to quantify S. rebaudiana glycosides, assess cytotoxicity of the extract and its acute and chronic effect on blood glucose in animal models and in human. The glycosides of the Morita II and Criolla extract were quantified by HPLC, using a C18 column (250 mm x 4.6 mm and particle size of 5 uM) with UV detection at 210 nm, mobile phase of acetonitrile/sodium phosphate buffer 10 mmol/L, pH 2.6 (32:68 v/v). Cytotoxicity study was performed in Vero cells, whereas an intraperitoneal glucose tolerance test (IPGTT) and a chronic consumption assay (4 weeks) were executed in an animal model of diabetes; finally the glycemic index (G.I.) was determined in healthy individuals. The glycoside content is higher in the Morita variety II although both had a CC50 >300 µg/mL. The areas under the curve of the IPGTT and fasting glucose of the animals were not significantly different (p> 0.05) and the I.G. extract was 11.11 %, which classifies the extract as low I.G. The extract of S. rebaudiana Morita II has a low glycemic index and, in the doses tested, is not cytotoxic nor has acute or chronic effect on blood sugar, which makes it a safe sweetener (AU)

Propriedades terapêuticas de Stevia rebaudiana Bertoni / Propriedades terapéuticas de Stevia rebaudiana Bertoni / Therapeutic properties of Stevia rebaudiana Bertoni

Stevia rebaudiana é uma planta de porte herbáceo originária da Amé-rica do Sul com elevada capacidade adoçante devido à presença de glicósidos do esteviol: esteviósido e rebaudiósido A. Atualmente, re-presenta um dos adoçantes mais seguros e versáteis cujo consumo está a aumentar, podendo constituir uma possível alternativa tera-pêutica nos casos de diabetes tipo 2, hipertensão e diarreia. Existem também artigos publicados que referem uma ação antimicrobiana e antioxidante. Tais propriedades são conferidas pelos seus constituin-tes, tais como os glicósidos do esteviol, taninos, fruto-oligossacáridos e ácidos gordos obtidos a partir de diversos extratos e de diferentes partes da planta. São necessários mais estudos para melhor conhecer as potencialidades desta planta

Stevia rebaudiana es una planta herbácea de América del Sur con capacidad edulcorante debido a glucósidos de esteviol: esteviósido y rebaudiósido A. En la actualidad, es uno de los edulcorantes más seguros y versátiles cuyo consumo va en aumento y puede constituir una posible alternativa terapéutica en casos de diabetes tipo 2, hipertensión y diarrea. También hay artículos publicados que citan su actividad antimicrobiana y antioxidante. Estas propiedades son debidas a sus constituyentes, como los glucósidos de esteviol, taninos, frutooligosacáridos y ácidos grasos obtenidos a partir de extractos de diferentes partes de la planta. Se necesitan más estudios para comprender mejor el potencial de esta planta (AU)

Stevia rebaudiana is a shrub from South America with sweetener capacity due to the presence of steviol glycosides: stevioside and rebaudioside A. Currently, is one of the safest and versatile sweetener whose consumption is increasing, being a possible therapeutic alternative in type 2 diabetes, hypertension and diarrhoea. Studies referring to its antimicrobial and antioxidant activity have also been published. Such properties are from its constituents: steviol glycosides, tannins, fructooligosaccharides and fatty acids obtained from extracts and from different plant parts. More studies ere needed to better understand the plant activities (AU)

Artificial sweeteners stimulate adipogenesis and suppress lipolysis independently of sweet taste receptors.

G protein-coupled receptors mediate responses to a myriad of ligands, some of which regulate adipocyte differentiation and metabolism. The sweet taste receptors T1R2 and T1R3 are G protein-coupled receptors that function as carbohydrate sensors in taste buds, gut, and pancreas. Here we report that sweet taste receptors T1R2 and T1R3 are expressed throughout adipogenesis and in adipose tissues. Treatment of mouse and human precursor cells with artificial sweeteners, saccharin and acesulfame potassium, enhanced adipogenesis. Saccharin treatment of 3T3-L1 cells and primary mesenchymal stem cells rapidly stimulated phosphorylation of Akt and downstream targets with functions in adipogenesis such as cAMP-response element-binding protein and FOXO1; however, increased expression of peroxisome proliferator-activated receptor γ and CCAAT/enhancer-binding protein α was not observed until relatively late in differentiation. Saccharin-stimulated Akt phosphorylation at Thr-308 occurred within 5 min, was phosphatidylinositol 3-kinase-dependent, and occurred in the presence of high concentrations of insulin and dexamethasone; phosphorylation of Ser-473 occurred more gradually. Surprisingly, neither saccharin-stimulated adipogenesis nor Thr-308 phosphorylation was dependent on expression of T1R2 and/or T1R3, although Ser-473 phosphorylation was impaired in T1R2/T1R3 double knock-out precursors. In mature adipocytes, artificial sweetener treatment suppressed lipolysis even in the presence of forskolin, and lipolytic responses were correlated with phosphorylation of hormone-sensitive lipase. Suppression of lipolysis by saccharin in adipocytes was also independent of T1R2 and T1R3. These results suggest that some artificial sweeteners have previously uncharacterized metabolic effects on adipocyte differentiation and metabolism and that effects of artificial sweeteners on adipose tissue biology may be largely independent of the classical sweet taste receptors, T1R2 and T1R3.

Sodium ferric gluconate (SFG) in complex with sucrose for IV infusion: bioequivalence of a new generic product with the branded product in healthy volunteers.

OBJECTIVE: Parenteral sodium ferric gluconate in complex (Ferrlecit [branded SFG]) is used to treat patients with iron deficiency anemia undergoing chronic hemodialysis and receiving supplemental epoetin. This comparative pharmacokinetic study (GeneraMedix, Inc., Study 17909) evaluates whether the recently approved generic product Nulecit (generic SFG) and the branded product Ferrlecit (branded SFG) are bioequivalent. METHODS: In this open-label study, 240 healthy volunteers in a fasting state were assigned randomly to a single 10-min intravenous (IV) infusion of 125 mg of generic or branded SFG. Total and transferrin-bound iron concentrations were determined for the 36-h period after infusion and corrected for pretreatment levels. Maximum concentration (Cmax) and area under the concentration-time curve of 0 to 36 h (AUC[0-36]) were compared between the two products. Demonstration of bioequivalence required that the 90% confidence intervals of each parameter evaluated for generic SFG were within 80% to 125% of the corresponding values for branded SFG. RESULTS: Uncorrected and baseline-corrected mean serum concentrations of total serum iron during the 36-h assessment period were similar for generic and branded SFG. For total serum iron, the geometric mean ratios of corrected Cmax and AUC[0-36] were 100%. For transferrin-bound iron, the geometric mean ratios were 87% for corrected Cmax and 92% for corrected AUC[0-36]. All associated 90% confidence intervals were within the range of 80% to 125%. CONCLUSIONS: A new generic SFG in complex for IV infusion is bioequivalent to the branded SFG in complex for IV infusion. The generic SFG is AB rated by the FDA and considered therapeutically equivalent to the branded product.

Stevioside and related compounds: therapeutic benefits beyond sweetness.

Stevioside, an abundant component of Stevia rebaudiana leaf, has become well-known for its intense sweetness (250-300 times sweeter than sucrose) and is used as a non-caloric sweetener in several countries. A number of studies have suggested that, beside sweetness, stevioside along with related compounds, which include rebaudioside A (second most abundant component of S. rebaudiana leaf), steviol and isosteviol (metabolic components of stevioside) may also offer therapeutic benefits, as they have anti-hyperglycemic, anti-hypertensive, anti-inflammatory, anti-tumor, anti-diarrheal, diuretic, and immunomodulatory actions. It is of interest to note that their effects on plasma glucose level and blood pressure are only observed when these parameters are higher than normal. As steviol can interact with drug transporters, its role as a drug modulator is proposed. This review summarizes the current knowledge of the pharmacological actions, therapeutic applications, pharmacokinetics and safety of stevioside and related compounds. Although much progress has been made concerning their biological and pharmacological effects, questions regarding chemical purity and safety remain unsolved. These issues are discussed to help guide future research directions.

Dissolution of xylitol from a food supplement administered with a novel slow-release pacifier: preliminary results.

AIM: The aim of the study was to monitor the pattern of release and salivary xylitol concentrations during sucking of a slow-release pacifier used to deliver a novel food supplement. METHODS: The food supplement tablet contained 300 mg xylitol and 0.5 x 10(10) colony-forming units of Bifidobacterium lactis Bb-12 (Bb-12). The reference tablet contained 300 mg xylitol and was used by 10 adults (mean age 32 years) in the study. Whole saliva samples were collected with 2.5 min intervals during pacifier sucking. The salivary xylitol concentrations were determined using an enzyme assay kit. RESULTS: All subjects showed salivary xylitol concentrations exceeding 1% at least at one collection point. The xylitol and xylitol-Bb-12 tablets showed similar dissolving with no clear concentration peaks (comparison of saliva collection times; p = 0.139). CONCLUSION: Xylitol released from the food supplement, delivered with the novel pacifier, may result in salivary xylitol concentrations high enough to inhibit mutans streptococci in vivo.

Absorption and metabolism of glycosidic sweeteners of stevia mixture and their aglycone, steviol, in rats and humans.

Stevia mixture, sweeteners extracted from the leaves of Stevia rebaudiana Bertoni, consists mainly of the glycosides of the diterpene derivative steviol. The aims of this study were to investigate the absorption (in rats) and the hepatic metabolism (in rats and humans) of both stevia mixture and steviol. Absorption was investigated both in vivo and ex vivo. In ex vivo experiments using the rat everted sac method, no absorption of stevia mixture was observed, but significant absorption of steviol was noted (equivalent to approximately 70% of the absorption reference- salicylic acid- value). In the in vivo experiment, rats received a single oral administration of either steviol or stevia mixture; a peak steviol concentration in plasma was observed 15 min after its oral administration, demonstrating rapid absorption. However, after oral administration of stevia mixture, the steviol concentration in plasma increased steadily over 8 h, suggesting that stevia mixture components are first degraded and then absorbed as steviol in the rat intestine. Steviol metabolism in humans and rats was examined by incubating steviol with liver microsomes from the two species. Oxidative (monohydroxy and dihydroxy) metabolites of steviol were observed by LC-ESI/MS after incubation with both human and rat liver microsomes. The intrinsic clearance of steviol in human liver microsomes was 4-times lower than that found in rat liver microsomes. In conclusion, this study suggests that there are no major species differences in steviol hepatic metabolism between rats and humans. Absorption from the human intestine can be predicted to occur in an analogous manner to that from the rat intestine.

Metabolism of stevioside by chickens.

In intubation experiments (643-1168 mg per animal), most of the stevioside administered to chickens was recovered unchanged in the excreta, and only about 2% was converted into steviol. Neither stevioside nor steviol could be found in the blood. In chronic studies (667 mg of stevioside/kg of feed) with laying hens and meat-type chickens, no significant differences were found in feed uptake, weight gain, and feed conversion as the result of stevioside administration. The egg production and egg composition of laying hens were not influenced. Most of the stevioside taken up was found untransformed in the excreta, and about 21.5% or 7.3% was converted to steviol by meat-type chickens or laying hens, respectively. No stevioside or steviol could be detected in the blood or in the eggs of the different groups of animals. In anaerobic incubation experiments with chicken excreta, only a 20% conversion of stevioside into steviol was found. No harmful effects were observed in the chronic stevioside supplementation experiments nor in the intubation experiments in which very high stevioside doses were given.

In vitro metabolism of the glycosidic sweeteners, stevia mixture and enzymatically modified stevia in human intestinal microflora.

Stevia mixture, sweeteners extracted from the leaves of Stevia rebaudiana Bertoni, consists mainly of stevioside and rebaudioside A (glycosides of the diterpene derivative steviol). The aim of this study was to investigate human intestinal metabolism of stevia mixture and its alpha-glucose derivative (known in Japan as enzymatically modified stevia) by LC/MS/ESI analysis. Degradation was examined by incubating stevia mixture, enzymatically modified stevia, stevioside, rebaudioside A, alpha-monoglucosylstevioside, alpha-monoglucosylrebaudioside A and the aglycone, steviol with pooled human faecal homogenates (obtained from five healthy volunteers) for 0, 8 and 24 h under anaerobic conditions. Stevia mixture, enzymatically modified stevia, stevioside and rebaudioside A (0.2 mg/ml) were completely eliminated within 24 h, whereas no degradation of steviol (0.08 and 0.2 mg/ml) appeared to be found during the incubation period. Stevia mixture, stevioside and rebaudioside A appeared to be hydrolyzed to steviol by human intestinal microflora: this observation is consistent with previous rat metabolism studies. Similarly, enzymatically modified stevia appeared to be metabolized via stevia components and, finally, to steviol. This study suggests that there are apparently no species differences in intestinal metabolism of stevia mixture between rats and humans.

Tagatose, the new GRAS sweetener and health product.

Tagatose, a low-calorie, full-bulk natural sugar, has just attained GRAS (Generally Recognized As Safe) status under U.S. Food and Drug Administration (FDA) regulations, thereby permitting its use as a sweetener in foods and beverages. This paper presents all current aspects of tagatose with respect to demonstrated food and beverage applications and the potential health and medical benefits of this unique substance. Summarized studies are referenced to detailed peer-reviewed papers. The safety studies followed the recommendations in the FDA "Red Book." Results were submitted to an Expert Panel for determination of GRAS status under FDA regulation. Small phase 2 clinical trials showed tagatose to be effective in treating type 2 diabetes. The results, buttressed by the references cited, support the efficacy of the various applications disclosed for tagatose. Tagatose has been found to be safe and efficacious for use as a low-calorie, full-bulk sweetener in a wide variety of foods, beverages, health foods, and dietary supplements. It fills broad, heretofore unmet needs for a low-calorie sweetener in products in which the bulk of sugar is important, such as chocolates, chewing gum, cakes, ice cream, and frosted cereals. Its synergism with high-intensity sweeteners also makes it useful in sodas. Various health and medical benefits are indicated, including the treatment of type 2 diabetes, hyperglycemia, anemia, and hemophilia and the improvement of fetal development.

Effect of crude extract of Stevia rebaudiana on renal water and electrolytes excretion.

To evaluate the effect of crude extract of Stevia rebaudiana on renal water, Na+ and K+ excretion, male Wistar rats (250-350 g each) under antidiuresis or water diuresis conditions, were evaluated. During intravenous infusion of the extract (0.05 mg/min/100 g) no significant differences were detected in mean arterial pressure or renal hemodynamics parameters. In contrast, fractional water and sodium excretion and solute clearance increased significantly, in both groups of animals. In antidiuresis rats the extract significantly increased reabsorption of water by the collecting duct and in water diuresis animals the extract significantly increased free water clearance. The data suggest preferential action of the extract in the proximal tubular cells involved with salt transport mechanism.