Non-Cytotoxic Sulfated Heterorhamnan from Gayralia brasiliensis Green Seaweed Reduces Driver Features of Melanoma Metastatic Progression.

Melanoma is a form of skin cancer with high mortality owing to its fast progression and metastatic capacity. The treatments available nowadays are only palliative in advanced stages of the disease. Thus, alternative therapies for cancer treatment are in demand, and molecules from natural sources, such as polysaccharides, could represent new possible therapeutic approaches. Polysaccharides of freshwater and marine algae with biological activities, such as antitumor properties, are greatly reported in the scientific literature. In the present study, a sulfated heterorhamnan obtained from the green seaweed Gayralia brasiliensis (Gb1 fraction) was chemically characterized and its biological activities in the B16-F10 murine melanoma cell line were evaluated. The Gb1 polysaccharidic fraction tested concentrations presented low or absence of cytotoxicity to B16-F10 cells and neither cell proliferation nor cell cycle were altered. Interestingly, Gb1 treatment decreased B16-F10 cells migration and invasion capabilities and CD44 labeling, showing to be a promising compound for further in vitro and in vivo antitumor studies.

In vitro antiviral activity of some uridine derivatives of 2-deoxy sugars against classical swine fever virus.

Classical swine fever virus glycoproteins: E2, E(rns) (E0) and E1 are detected on the external part of viral particles and play a major role in the initial stages of viral infection. They form heterodimeric and homodimeric complexes needed to effectively infect host cells. Some glycosylation inhibitors, such as tunicamycin, which act at the early stages of glycan chain processing, can influence, not only glycosylation, but also the stability of E2 and E(rns) glycoproteins, effectively inhibiting the formation of glycoprotein complexes and virus yield. In our study we tested two of newly designed uridine derivatives of 2-deoxy sugars, IW3 and IW7 mimicking part of tunicamycin. We showed that inhibitors effectively arrest viral growth with IC(50) of 9 and 7microg/ml respectively, without significant toxicity for mammalian cells. Moreover, IW3 and IW7 reduced the formation of viral glycoproteins E2 and E(rns) in a dose-dependent manner. These compounds were further studied in order to elucidate the molecular mechanism of the antiviral effect using mammalian SK6 and insect Sf9 cell lines. We found that they inhibit N-glycosylation process of viral proteins at the late stage of glycan modification characteristic for mammalian cells. Due to the observed antiviral effect accompanied by low cytotoxicity, these inhibitors are potential candidates for anti-pestivirus therapy.

Chemical structure and antiviral activity of the sulfated heterorhamnan isolated from the green seaweed Gayralia oxysperma.

A homogeneous sulfated heterorhamnan was obtained by aqueous extraction, then by ultrafiltration from the green seaweed Gayralia oxysperma. Besides alpha-L-rhamnose it contains glucuronic and galacturonic acids, xylose and glucose. The structure was established by methylation analyses of the carboxyl-reduced, carboxyl-reduced/desulfated, carboxyl-reduced/Smith-degraded, and carboxyl-reduced/Smith-degraded/desulfated products and 1D, 2D NMR spectroscopy analyses. The heterorhamnan backbone is constituted by 3- and 2-linked rhamnosyl units (1.00:0.80), the latter being approximately 50% substituted at C-3 by side chains containing 2-sulfated glucuronic and galacturonic acids and xylosyl units. The 3- and 2-linked rhamnosyl units are unsulfated (20%), disulfated (16%), and mostly monosulfated at C-2 (27%) and C-4 (37%). The branched and sulfated heterorhamnan had high and specific activity against herpes simplex virus.

Lack of antifertility properties of novel halogenated glycolytic inhibitors and the urinary excretion and metabolism of 1,6-dichloro-1,6-dideoxy-D-fructofuranose in the male rat.

The antifertility action of (R,S)-alpha-chlorohydrin administered orally to male rats was compared with that of several novel chlorinated compounds known to inhibit glycolysis and the kinematics of rat sperm in vitro. Oral gavage of 1,6-dichloro-1,6-dideoxy-D-fructofuranose (dichlorodideoxyfructose, DCF), 1-chloro-3-hydroxypropanone, its dimethylketal and bromopyruvate did not reduce the fertility of male rats below that of controls at the equivalent antifertility dose of (R,S)-alpha-chlorohydrin (5 mg/kg/day) or higher. As anticipated for a compound cleaved to products of (S)-chirality even high doses of DCF (200 mg/kg) showed no effect on renal function. 36Cl-Labelled DCF administered orally to male rats was eliminated only slowly in the urine (16% of the ingested dose excreted in 96 h). In the first 8 h, approximately 50% of DCF was excreted unchanged, 30% was excreted as 3-chlorolactate (BCLA), the oxidation product 3-chlorolactaldehyde and 25% as Cl-. By 24 h little DCF remained and the major metabolite (70%) was BCLA and 20% Cl-. The high rate of dechlorination is most likely responsible for the low antifertility action of DCF.

Neurotoxicity studies on sucralose and its hydrolysis products with special reference to histopathologic and ultrastructural changes.

Comparative neuropathological studies of 1,6-dichloro-1, 6-dideoxy-beta-D-fructofuranosyl-4-chloro-4-deoxy-alpha-D-galactopyra noside (sucralose), an equimolar mixture of 1,6-dichloro-1, 6-dideoxyfructose (1,6-DCF) and 4-chloro-4-deoxygalactose (4-CG), the hydrolysis products of sucralose, and 6-chloro-6-deoxyglucose (6-CG) were conducted in male and female mice and male marmoset monkeys, focusing on morphological changes in the central nervous system. 6-Chloro-6-deoxyglucose, previously reported to produce neurotoxic effects, served as the positive control and was administered by gavage at a daily dose of 500mg/kg. Sucralose and the sucralose hydrolysis products (sucralose-HP) were similarly administered to mice and marmosets at doses of up to 1000mg/kg for 21 and 28 days, respectively. No changes were detected in the central nervous system by light or electron microscopy in either of the species that received sucralose or its hydrolysis products. 6-Chloro-6-deoxyglucose, in contrast, induced symmetrical lesions in the deep nuclei of the cerebellum, brain stem and spinal cord with definitive neurological signs of CNS involvement.

Alkylating agents from sugars. Alkyl hexopyranoside derivatives as carrier systems for chlorambucil.

Chlorambucil derivatives involving alkyl 2-aminodeoxy sugars have been synthesized in good yield by coupling the chlorambucil moiety to positions C-2 or C-3 of the sugar, directly or via a spacer. The starting material was easily available from 2-acetamido-2-deoxy-D-glucose. The final compounds were tested for cytotoxicity, and some of those that presented the best results were studied for inhibition of cell proliferation.

Teratogenic effects of a lipophilic cationic dye rhodamine 123, alone and in combination with 2-deoxyglucose.

An anti-tumor agent, the cationic dye rhodamine 123 (Rh 123), becomes concentrated in mitochondria of certain tissues and inhibits ATP production. Rh 123 was tested for developmental toxicity by i.p. injection into pregnant CD-1 mice daily on gestation days 7-10 (plug = day 1) at doses up to 15 mg/kg/day. Additional mice were given a 500 mg/kg/day dose of 2-deoxy-glucose (2-DOG), an inhibitor of glycolytic ATP generation, alone or with Rh 123. Controls received saline equimolar to the 2-DOG. Prenatal mortality was increased by Rh 123 in combination with 2-DOG, with values of 40%, 43%, or 41% dead or resorbed at Rh 123 doses of 8, 12, or 15 mg/kg/day, respectively. When given alone, neither test agent was associated with a significant increase in prenatal death. Concurrent treatment with Rh 123 and 2-DOG resulted in significant incidences of gross malformations (17% to 20%) and skeletal malformations (9% to 72%). At the two highest Rh 123 doses (12 and 15 mg/kg/day) given with 2-DOG, significant findings included retarded skeletal ossification and variations (up to 83% and 41%, respectively), as well as decreased fetal weight. According to these results, combinations of rhodamine 123 and 2-deoxyglucose administered to the dam during early organogenesis are developmentally toxic to mice.

Amadori- and N-nitroso-Amadori compounds and their pyrolysis products. Chemical, analytical and biological aspects.

N-(1-Deoxy-D-fructos-1-yl)-L-amino acids (fructose amino acids), Amadori compounds, are formed by reaction of D-glucose and L-amino acids and Amadori rearrangement. They are detected in heat-processed natural products and various foodstuffs and are key products of the Maillard-Browning reaction. N-Nitroso-N-(1-deoxy-D-fructos-1-yl)-L-amino acids (N-NO-fructose amino acids), N-NO-Amadori compounds, are formed in high yields by reacting fructose amino acids with sodium nitrite in acidic aqueous solution. They constitute a new class of non-volatile, bis-beta-oxidized nitrosamine derivatives with unknown biological (mutagenic and/or carcinogenic) activity. N-NO-Fructose amino acids may be formed in nitrite-containing Maillard systems (e.g., cured-meat products, tobacco) or in the human stomach after ingestion of food containing fructose amino acids and nitrite in food or saliva. Thirteen fructose amino acids and 13 N-NO-fructose amino acids (-gly, -ala, -val, -leu, -ileu, -ser, -thr, -met, -asp, -pheala, -tyr, -his, -trp) were prepared and investigated by high-resolution 1H-nuclear magnetic resonance (NMR) and 13C-NMR spectroscopy. The percentage amounts of the sugar ring forms (beta-pyranose, beta-furanose, alpha-furanose and alpha-pyranose) of these compounds in D2O mutarotation equilibrium were determined by 13C-NMR spectroscopy, together with the amounts (%) of E/Z isomers in the case of N-NO-compounds. The nitrosation products of D-fru-L-tyr, D-fru-L-his and D-fru-L-trp were isolated and identified by spectroscopic methods (NMR, infra-red). The N-NO-fructose amino acids can be separated by reversed-phase, ion-pairing, high-performance liquid chromatography. In some case the E/Z isomers are separated.

Transient toxicity of 2-deoxy-2-[18F]fluoro-D-glucose in mammalian cells: concise communication.

The kinetics of uptake and toxicity of the positron emitter F-18 have been examined in a cultured cell line. 2-Deoxy-2[18F]fluoro-D-glucose (18FDG) concentrated rapidly within Chinese hamster V79 cells, and the uptake was linear with the extracellular radioactive concentrations. Whereas 18FDG synthesized 2 hr before the incubation did not appear to be toxic, that synthesized 5 hr previously was highly toxic. Toxicity was transient and independent of both the extracellular/intracellular radioactive concentration and the energy released from the decay of fluorine-18. Similarly synthesized nonradioactive FDG and Na 18F were not toxic under comparable experimental conditions. We conclude that this transient toxicity is due to an unidentified chemical species that is cytocidal following intracellular localization. These toxic levels are not likely to be achieved in the clinical use of 18FDG due to dilution factors that are orders of magnitude greater than those used in these in vitro studies.

Acute toxicity of 3-deoxy-4-sulphohexosulose in rats and mice, and in vitro mutagenicity in the Ames test.

3-Deoxy-4-sulphohexosulose (DSH) is formed in sulphited foods by the interaction of SO2 and intermediates of the Maillard reaction. The acute intragastric toxicity of DSH has been studied in rats and mice, and the LD50 was found to exceed 5 g/kg body weight in both species. The only adverse effect seen in a 14-day post-dosing period was a transient diarrhoea in the first 24 hr. DSH was shown to be non-mutagenic in four strains of Salmonella typhimurium in the Ames test, with and without metabolic activation by S-9 mix from Aroclor-treated rats.

Gastric antral ulcers produced by the combined administration of indomethacin with 2-deoxy-D-glucose in the rat.

The influence of 2-deoxy-D-glucose (2DG) on indomethacin ulcers was studied in rats. 2DG (200 mg/kg i.v.) produced large round ulcers in the lesser curvature of the antrum and aggravated lesions of the corpus 6 h after treatments in indomethacin (40 mg/kg i.p.)-treated rats. Insulin (5 units/kg i.v.) also produced gastric antral ulcers similarly to 2DG. Antral ulcers were revealed rather clearly 48 h after the administration of indomethacin and 2DG when the corpus lesion index was reduced. 2DG or insulin had only a slight influence on the severity of other experimental gastric ulcers. Peripheral gastric secretagogues, bethanechol (1 mg/kg s.c. X 2) or histamine (10 mg/kg s.c. X 2) did not produce antral ulcers at the gastric secretory dose in the indomethacin-treated rats. High doses of atropine (1.0 and 10 mg/kg s.c.) prevented gastric antral ulcers. The combined administration of indomethacin with 2DG produced gastric antral ulcers similar to human gastric ulcers in rats. The combination of gastric acid secretion, vagus nerve stimulation and some other factors may be involved in gastric antral ulcers produced in rats.

The effect of high doses of 6-chloro-6-deoxyglucose on the rat.

Male rats given 6-chloro-6-deoxyglucose (240 mg/kg/day for 28 days) developed spermatocoeles in their ductuli efferentes or caput epididymides. They had a lower serum triglyceride content than controls (0.87 +/- 0.19 vs 1.84 +/- 0.19 mM, Mean +/- SEM; n = 6) and gained less weight (2.55 +/- 0.37 vs 4.1 +/- 0.96 g/day, Mean +/- SEM; n = 6). There was no effect on female rats which received the same treatment. Spermatocoeles could also be produced by a single dose of 6-chloro-6-deoxyglucose, the threshold dose was between 180 and 240 mg/kg. Glucose oxidation by liver, brain, kidney and diaphragm from rats given 6-chloro-6-deoxyglucose (240 mg/kg/day for 14 days) was the same as in controls but was decreased in seminiferous tubules (0.32 +/- 0.06 vs 0.74 +/- 0.02 mumol [U-14C]glucose oxidised to 14CO2/g fresh wt/h, Mean +/- SEM; n = 3). The activity of glyceraldehyde-3-phosphate dehydrogenase [E.C. 1.2.1.12] in liver, brain, testis or muscle from rats given 6-chloro-6-deoxyglucose (24 mg/kg/day for 14 days) showed little change although its activity in spermatozoa was dramatically decreased.

The neurotoxicity and antifertility properties of 6-chloro-6-deoxyglucose in the mouse.

6-chloro-6-deoxyglucose (24 mg/kg/day) produces infertility in male rats and marmosets. In the present study very high doses (480 mg/kg/day) were found not to impair the fertility of male mice. However, such doses induced the formation of vacuolated lesions in specific regions of central nervous system grey matter causing varying degrees of physical disability. A similar response has been obtained in marmosets. Astrocytes appear to be primarily affected with later involvement of nerve cells. The sites of lesions correspond closely to regions of high glucose utilization.