RESUMEN
The relation between earthquakes and volcanic eruptions, each of which is manifested by large-scale tectonic plate and mantle motions, has been widely discussed. Mount Fuji, in Japan, last erupted in 1707, paired with a magnitude (M)-9-class earthquake 49 days prior. Motivated by this pairing, previous studies investigated its effect on Mount Fuji after both the 2011 M9 Tohoku megaquake and a triggered M5.9 Shizuoka earthquake 4 days later at the foot of the volcano, but reported no potential to erupt. More than 300 years have already passed since the 1707 eruption, and even though consequences to society caused by the next eruption are already being considered, the implications for future volcanism remain uncertain. This study shows how volcanic low-frequency earthquakes (LFEs) in the deep part of the volcano revealed unrecognized activation after the Shizuoka earthquake. Our analyses also show that despite an increase in the rate of occurrence of LFEs, these did not return to pre-earthquake levels, indicating a change in the magma system. Our results demonstrate that the volcanism of Mount Fuji was reactivated by the Shizuoka earthquake, implying that this volcano is sufficiently sensitive to external events that are considered to be enough to trigger eruptions.
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Terremotos , Erupciones Volcánicas , JapónRESUMEN
Six new species of the genus Hercostomus Loew, 1857, are described from Japan: Hercostomus acutiformis Negrobov, Kumazawa & Tago sp. nov., H. falcilis Negrobov, Kumazawa & Tago sp. nov., H. flavipalpus Negrobov, Kumazawa, Tago & Sato sp. nov., H. nigricollaris Negrobov, Kumazawa & Tago sp. nov., H. spathulatus Negrobov, Kumazawa, Tago & Sato sp. nov., H. spinitibialis Negrobov, Kumazawa & Tago sp. nov. Hercostomus flaveolus Negrobov & Chalaya, 1987 is newly recorded from Japan, and Hercostomus arcticus Yang, 1996 is newly synonymized with Hercostomus flaveolus (syn. nov.). The holotype of Hercostomus flaviventris Smirnov & Negrobov, 1979 is redescribed. Hercostomus ussurianus Stackelberg is transferred to the genus Gymnopternus Loew, 1857 (stat. nov.). A key to the eleven recognized species of Japanese Hercostomus is provided.
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Dípteros/clasificación , Estructuras Animales/anatomía & histología , Estructuras Animales/crecimiento & desarrollo , Animales , Tamaño Corporal , Dípteros/anatomía & histología , Dípteros/crecimiento & desarrollo , Femenino , Japón , Masculino , Tamaño de los ÓrganosRESUMEN
The BESS-Polar Collaboration measured the energy spectra of cosmic-ray protons and helium during two long-duration balloon flights over Antarctica in December 2004 and December 2007, at substantially different levels of solar modulation. Proton and helium spectra probe the origin and propagation history of cosmic rays in the galaxy, and are essential to calculations of the expected spectra of cosmic-ray antiprotons, positrons, and electrons from interactions of primary cosmic-ray nuclei with the interstellar gas, and to calculations of atmospheric muons and neutrinos. We report absolute spectra at the top of the atmosphere for cosmic-ray protons in the kinetic energy range 0.2-160 GeV and helium nuclei 0.15-80 GeV/nucleon. The corresponding magnetic rigidity ranges are 0.6-160 GV for protons and 1.1-160 GV for helium. These spectra are compared to measurements from previous BESS flights and from ATIC-2, PAMELA, and AMS-02. We also report the ratio of the proton and helium fluxes from 1.1 GV to 160 GV and compare to ratios from PAMELA and AMS-02.
RESUMEN
INTRODUCTION: The number of infused CD34(+) cells is crucial to the success of peripheral blood stem cell transplantation (PBSCT). Here, we present, for the first time, a new method of enumerating hematopoietic progenitor cells (HPCs) for PBSCT. METHOD: This novel method is based on hemolysis and chemical staining, followed by flow cytometry-based optical detection, conducted using an automated hematology analyzer (XN series, Sysmex). CD34(+) cells and HPCs were compared in 76 granulocyte colony-stimulating factor (G-CSF)-mobilized blood or apheresis samples taken from healthy donors (n = 18) or patients undergoing autologous PBSCT (n = 6). RESULTS: There was a strong correlation between the numbers of HPCs and CD34(+) cells (R(2) = 0.958). The expected total number of HPCs in the final products, which was estimated from HPCs in pre-apheresis PB or mid-apheresis products, also correlated well with the total number of CD34(+) cells in the final products. The change in HPCs in PB closely resembled that of CD34(+) cells during mobilization. Experiments using immunomagnetic beads suggested that the majority of CD34(+) cells existed in HPCs, and vice versa. CONCLUSION: Hematopoietic progenitor cells may serve as surrogates for CD34(+) cells in PBSCT. However, further investigations are required to verify this.
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Recuento de Células Sanguíneas/métodos , Células Sanguíneas/citología , Neoplasias Hematológicas/terapia , Células Madre Hematopoyéticas/citología , Trasplante de Células Madre de Sangre Periférica , Antígenos CD34/sangre , Automatización de Laboratorios , Biomarcadores/sangre , Recuento de Células Sanguíneas/instrumentación , Estudios de Casos y Controles , Factor Estimulante de Colonias de Granulocitos/farmacología , Neoplasias Hematológicas/patología , Movilización de Célula Madre Hematopoyética , Células Madre Hematopoyéticas/efectos de los fármacos , Hemólisis , Humanos , Trasplante AutólogoRESUMEN
In two long-duration balloon flights over Antarctica, the Balloon-borne Experiment with a Superconducting Spectrometer (BESS) collaboration has searched for antihelium in the cosmic radiation with the highest sensitivity reported. BESS-Polar I flew in 2004, observing for 8.5 days. BESS-Polar II flew in 2007-2008, observing for 24.5 days. No antihelium candidate was found in BESS-Polar I data among 8.4×10(6) |Z|=2 nuclei from 1.0 to 20 GV or in BESS-Polar II data among 4.0×10(7) |Z|=2 nuclei from 1.0 to 14 GV. Assuming antihelium to have the same spectral shape as helium, a 95% confidence upper limit to the possible abundance of antihelium relative to helium of 6.9×10(-8)} was determined combining all BESS data, including the two BESS-Polar flights. With no assumed antihelium spectrum and a weighted average of the lowest antihelium efficiencies for each flight, an upper limit of 1.0×10(-7) from 1.6 to 14 GV was determined for the combined BESS-Polar data. Under both antihelium spectral assumptions, these are the lowest limits obtained to date.
RESUMEN
It has been postulated that physical immobilization is an essential factor in developing chronic pain after trauma or surgery in an extremity. However, the mechanisms of sustained immobilization-induced chronic pain remain poorly understood. The present study, therefore, aimed to develop a rat model for chronic post-cast pain (CPCP) and to clarify the mechanism(s) underlying CPCP. To investigate the effects of cast immobilization on pain behaviours in rats, one hindlimb was immobilized for 2 weeks with a cast and remobilization was conducted for 10 weeks. Cast immobilization induced muscle atrophy and inflammatory changes in the immobilized hindlimb that began 2 h after cast removal and continued for 1 week. Spontaneous pain-related behaviours (licking and reduction in weight bearing) in the immobilized hindlimb were observed for 2 weeks, and widespread mechanical hyperalgesia in bilateral calves, hindpaws and tail all continued for 5-10 weeks after cast removal. A sciatic nerve block with lidocaine 24 h after cast removal transitorily abolished bilateral mechanical hyperalgesia in CPCP rats, suggesting that sensory inputs originating in the immobilized hindlimb contribute to the mechanism of both ipsilateral and contralateral hyperalgesia. Intraperitoneal injection of the free radical scavengers 4-hydroxy-2,2,6,6-tetramethylpiperydine-1-oxy1 or N-acetylcysteine 24 h after cast removal clearly inhibited mechanical hyperalgesia in bilateral calves and hindpaws in CPCP rats. These results suggest that cast immobilization induces ischaemia/reperfusion injury in the hindlimb and consequent production of oxygen free radicals, which may be involved in the mechanism of widespread hyperalgesia in CPCP rats.
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Dolor Crónico/etiología , Hiperalgesia/etiología , Inmovilización/efectos adversos , Animales , Atrofia/etiología , Dolor Crónico/patología , Miembro Posterior/patología , Hiperalgesia/patología , Masculino , Músculo Esquelético/patología , Dimensión del Dolor , Estimulación Física , Ratas , Ratas Sprague-DawleyRESUMEN
In this study, the composite magnetic nanoparticles of coated SiO nano film with about 8 nm size and high saturation magnetization value, were synthesized by liquid phase precipitation method. The magnetic nanoparticles can be dispersed in various liquid media, widely known as magnetic fluids or ferrofluids with both magnetic and liquid properties. The materials been collected great interests and more and more attentions to focus into Drug Delivery System (DDS) as a new technology in this paper. We use the composite nanoparticles to disperse H2O and inject the solutions into rat's in-vivo organs. And, in the experiments by using a strong photon beam of SPring-8 Synchrotron Radiation facility, the distribution stat and the effects of magnetic field as well as drug delivery behaviour of nanoparticles in the rat' kidney are verified by the in-vivo observations.
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Sistemas de Liberación de Medicamentos/métodos , Nanopartículas de Magnetita/química , Óxidos/química , Dispersión de Radiación , Compuestos de Silicona/química , Dióxido de Silicio/química , Sincrotrones/instrumentación , Animales , Materiales Biocompatibles/química , Interacciones Hidrofóbicas e Hidrofílicas , Riñón/metabolismo , Campos Magnéticos , Magnetismo/métodos , Simulación de Dinámica Molecular , Tamaño de la Partícula , Fotones , Radiometría/instrumentación , Ratas , Soluciones/química , Agua/químicaAsunto(s)
Paro Cardíaco/inducido químicamente , Complicaciones Intraoperatorias , Inhibidores de Agregación Plaquetaria/efectos adversos , Síndrome de Abstinencia a Sustancias , Tetrazoles/efectos adversos , Antagonistas Adrenérgicos beta/efectos adversos , Anciano , Atenolol/efectos adversos , Cilostazol , Humanos , MasculinoRESUMEN
BACKGROUND: Comparable minimum alveolar concentration (MAC) fractions of volatile anaesthetics produce similar thermoregulatory impairment. Nitrous oxide, however, decreases the vasoconstriction threshold less than sevoflurane or isoflurane. We tested the hypothesis that nitrous oxide also decreases shivering threshold less than isoflurane alone or in combination. METHODS: Twenty-four rabbits were assigned randomly to one of three 0.3 MAC anaesthetic regimens: (i) nitrous oxide 69%; (ii) nitrous oxide 35% and isoflurane 0.3%; or (iii) isoflurane 0.6%. Body temperature was lowered by perfusing 10 degrees C water through a U-shaped thermode positioned in the colon. Shivering was evaluated by inspection. RESULTS: The rabbits anaesthetized with nitrous oxide alone shivered at 37.0 (0.5) degrees C (P<0.01 vs other groups). In those given the nitrous oxide and isoflurane combination, the shivering threshold was 36.4 (0.5) degrees C and that in the isoflurane group was 35.9 (0.4) degrees C. CONCLUSION: This study indicates that nitrous oxide reduces the shivering threshold less than isoflurane.
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Anestésicos por Inhalación/farmacología , Isoflurano/farmacología , Óxido Nitroso/farmacología , Tiritona/efectos de los fármacos , Animales , Regulación de la Temperatura Corporal/efectos de los fármacos , Masculino , Conejos , Tiritona/fisiologíaRESUMEN
BACKGROUND: Nicorandil, which is an ATP-sensitive K channel opener, has been reported to protect the ischaemic myocardium. However, its interaction with inhalation anaesthetics on the ischaemic myocardium has not been well elucidated. So, we have investigated whether isoflurane or sevoflurane modify the effects of nicorandil on cardiac function and metabolism in the rat heart-lung preparation. METHODS: Animals were allocated to 4 groups as follows: Control group, no drug; Nic group, nicorandil; Nic+Iso group, nicorandil and isoflurane; Nic+Sev group, nicorandil and sevoflurane. Seven minutes after the start of perfusion, nicorandil was administered and 10 min after the start of perfusion, the heart was rendered globally ischaemic for 10 min, and then the heart was reperfused for 10 min. RESULTS: LVdP/dt max in the Nic group was higher than those in the other groups. Right atrial pressure in the Nic+Iso and Nic+Sev groups was significantly higher than in the Control and Nic groups. Myocardial ATP in the Nic group was higher than in the other groups. DHBA levels in the perfusate in the Nic and Nic+Iso groups were lower than those in the Control and Nic+Sev groups, but those in the Nic+Sev group were higher than those in the other groups. CONCLUSIONS: Nicorandil improved post-ischaemic cardiac function and preserved high-energy phosphates. However, these beneficial effects of nicorandil were abolished by the combination with isoflurane or sevoflurane. In addition, sevoflurane increased hydroxyl radical formation in the post-ischaemic reperfused heart.
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Anestésicos por Inhalación/farmacología , Hemodinámica/efectos de los fármacos , Isoflurano/farmacología , Éteres Metílicos/farmacología , Reperfusión Miocárdica , Miocardio/metabolismo , Nicorandil/farmacología , Vasodilatadores/farmacología , Adenosina Trifosfato/metabolismo , Animales , Gentisatos/metabolismo , Corazón/efectos de los fármacos , Masculino , Canales de Potasio/efectos de los fármacos , Canales de Potasio/metabolismo , Ratas , Ratas Wistar , SevofluranoRESUMEN
BACKGROUND AND OBJECTIVE: We investigated whether glibenclamide (glyburide) affects myocardial metabolism and hydroxyl radical formation in the rat heart-lung preparation with or without inhalation anaesthetics. METHODS: Thirty-seven male Wistar rats were allocated to four groups: (a) control group (C), received vehicle only; (b) group G, received glibenclamide 10 microM L-1; (c) group I, received glibenclamide 10 microM L-1 and 1.4% isoflurane during perfusion; (d) group S, received glibenclamide 10 microM L-1 and 2.7% sevoflurane during perfusion. Glibenclamide was administered 7 min after the start of perfusion. Ten minutes later, the heart was rendered globally ischaemic for 10 min by reducing the preload and afterload to zero, and then the heart was reperfused for 10 min. The formation of hydroxyl radicals in perfusate blood and heart was measured with high performance liquid chromatography using salicylic acid. Hydroxyl radicals react with salicylic acid, yielding dihydroxybenzoic acids. RESULTS: The recovery time from ischaemia in group G was significantly longer than the other groups. However, there were no differences in myocardial metabolites and dihydroxybenzoic acids concentrations in the perfusate and heart among the four groups. CONCLUSIONS: Glibenclamide prolonged recovery time from ischaemia, but did not affect hydroxyl radical formation in the postischaemic reperfused heart. In addition, isoflurane and sevoflurane shortened this time. These facts suggest that mechanisms other than effects of volatile anaesthetics on hydroxyl radical formation are responsible for their protective effects in this model.
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Anestésicos por Inhalación/farmacología , Gliburida/farmacología , Radical Hidroxilo/metabolismo , Isoflurano/farmacología , Éteres Metílicos/farmacología , Reperfusión Miocárdica , Miocardio/metabolismo , Bloqueadores de los Canales de Potasio/farmacología , Adenosina Trifosfato/metabolismo , Animales , Glucógeno/metabolismo , Hemodinámica/efectos de los fármacos , Hidroxibenzoatos/metabolismo , Ácido Láctico/metabolismo , Masculino , Ácido Pirúvico/metabolismo , Ratas , Ratas Wistar , SevofluranoRESUMEN
STUDY OBJECTIVE: To test the hypothesis that core temperature is well preserved when atropine and midazolam are combined. DESIGN: Randomized, blinded study. SETTING: Department of Anesthesia, Yamanashi Medical University. PATIENTS: 40 elderly, ASA physical status I and II patients (aged more than 60 years). INTERVENTIONS: Patients were randomly assigned (n = 10 per group) to premedication with: 1) saline control; 2) midazolam 0.05 mg/kg; 3) atropine 0.01 mg/kg; and 4) midazolam 0.05 mg/kg combined with atropine 0.01 mg/kg. All premedication was given on the ward at approximately 8:30 am, approximately 30 minutes before induction of anesthesia. MEASUREMENTS AND MAIN RESULTS: Core temperatures were measured at the right tympanic membrane. Mean skin temperature was calculated as 0.3 x (T(chest) + T(arm)) + 0.2 x (T(thigh) + T(calf)). Fingertip perfusion was evaluated using forearm minus fingertip and calf minus toe, skin-surface temperature gradients. Temperatures were evaluated at the time of premedication and 30 minutes later, just before induction of anesthesia. Core temperature remained nearly constant in the control patients (0.1 +/- 0.2 degrees C; mean +/- SD), whereas it decreased significantly in the patients given midazolam alone (-0.3 +/- 0.1 degrees C). Atropine alone increased core temperature (0.3 +/- 0.2 degrees C), although the increase was not statistically significant. The combination of midazolam and atropine attenuated the hypothermia induced by midazolam alone (0.0 +/- 0.2 degrees C). Initial skin-temperature gradients exceeded 0 degrees C in all groups, indicating that the patients were vasoconstricted. The gradients were unchanged by premedication with saline or atropine. Midazolam significantly decreased the gradient (-1.8 +/- 1.1 degrees C), as did the combination of midazolam and atropine (-1.4 +/- 0.9 degrees C). CONCLUSIONS: The thermoregulatory effects of benzodiazepine receptor agonist and cholinergic inhibitors oppose each other, and the combination leaves core temperature unchanged.
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Atropina/farmacología , Hipotermia/prevención & control , Midazolam/efectos adversos , Premedicación , Anciano , Regulación de la Temperatura Corporal/efectos de los fármacos , Femenino , Hemodinámica/efectos de los fármacos , Humanos , Hipotermia/inducido químicamente , MasculinoRESUMEN
Four general anaesthetics, sevoflurane, isoflurane, enflurane and halothane, in human whole blood, have been found measurable with very high sensitivity by capillary gas chromatography-flame ionization detection (GC-FID) with cryogenic oven trapping upon injection of headspace (HS) vapor sample. To a 7-ml vial, containing 0.48 ml of distilled water and 20 microl of internal standard solution (5 microg), a 0.5-ml of whole blood sample spiked with or without anaesthetics, was added, and the mixture was heated at 55 degrees C for 15 min. A measure of 10 ml HS vapor was injected into the GC in the splitless mode at -40 degrees C oven temperature, which was programmed up to 250 degrees C. All four peaks were clearly separated; no impurity peaks were found among their peaks. Their extraction efficiencies were about 10%. The calibration curves showed good linearity in the range of 0.5-20 microg/ml; their detection limits were 10-100 ng/ml, which are almost comparable to those by previous reports. The coefficients of intra-day and day-to-day variations were 6.5-9.8 and 7.3-17.2%, respectively. Isoflurane or enflurane was also measured from whole blood samples in which three volunteers inhaled each compound.
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Anestésicos por Inhalación/sangre , Cromatografía de Gases/métodos , Adulto , Enflurano/sangre , Halotano/sangre , Calor , Humanos , Isoflurano/sangre , Masculino , Éteres Metílicos/sangre , Persona de Mediana Edad , Reproducibilidad de los Resultados , Sensibilidad y Especificidad , SevofluranoRESUMEN
The sterol fraction of Glycine max (soybean) was found to contain a mixture of 13 major sterols which differed dramatically in composition between seeds and shoots. Typical C4-desmethyl Delta(5)-sterols, including sitosterol, predominate the sterol mixture of shoots, whereas C4-methyl sterol intermediates, cycloartenol and 24(28)-methylene cycloartanol, accumulate in seeds. The significance of modified sterol profile of shoot compared to seed was relevant to the physiology of Phytophthora sojae, a phytopathogen of soybean shown to be auxotrophic for sterol. Sterols native to the host plant containing a C4-methyl group, such as cycloartenol, were not utilized by the fungus. Alternatively, all Delta(5)-sterols added to the culture media of P. sojae supported normal growth and promoted viable oospore production. The results demonstrate the importance of sterols in plant-fungal interactions and offer the possibility of bioengineering the phytosterol pathway for resistance to phytopathogens which scavenge specific sterols of the host plant to complete the life cycle.
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Glycine max/metabolismo , Phytophthora/metabolismo , Esteroles/metabolismo , Estructura Molecular , Phytophthora/crecimiento & desarrollo , Glycine max/química , Glycine max/microbiologíaRESUMEN
Congenital sensory neuropathy with anhydrosis is a rare disorder characterized by insensitivity to pain with normal tactile perception, self-mutilation, anhydrosis, recurrent unexplained fever, mental retardation and variable autonomic abnormality. We managed a 14-year-old boy with this syndrome who underwent repair of right femur fracture. Anesthesia was induced with propofol and ketamine. Adequate depth of anesthesia was carefully controlled by processed electroencephalogram, and core body temperature was maintained at 37.0 degrees C during the surgery. The patient was well sedated, and nausea and vomiting were not noted postoperatively. Use of droperidol and propofol may be beneficial for anesthetic management of this syndrome, because droperidol exerts residual hypnotic effect postoperatively, and both drugs have antiemetic property.
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Anestesia Intravenosa , Neuropatías Hereditarias Sensoriales y Autónomas , Adolescente , Droperidol , Electroencefalografía , Fracturas del Fémur/cirugía , Humanos , Ketamina , Masculino , Monitoreo Intraoperatorio , Procedimientos Ortopédicos , Náusea y Vómito Posoperatorios/prevención & control , PropofolRESUMEN
We have presented a simple and sensitive method for determining pethidine, a narcotic analgesic drug in body fluids by gas chromatography (GC)/surface ionization organic mass spectrometry (SIOMS). Good linearity was obtained in the range of 0.625-25 ng/ml of whole blood and urine by mass chromatography, and in the range of 0.05-2 ng/ml of whole blood by selected ion monitoring (SIM). Pethidine and diphenylpyraline (internal standard) were extracted from body fluids with Bond Elut Certify cartridges; their recoveries were above 95%. The detection limits (signal-to-noise ratio=3) were estimated to be 0.2 ng/ml of whole blood or urine by mass chromatography, 0.02 ng/ml of whole blood by SIM.
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Analgésicos Opioides/análisis , Líquidos Corporales/química , Espectrometría de Masas/métodos , Meperidina/análisis , Humanos , Masculino , Meperidina/sangre , Meperidina/orina , Reproducibilidad de los Resultados , Sensibilidad y EspecificidadRESUMEN
The syntheses of orientin, parkinsonin A, isoswertiajaponin, and parkinsonin B, which are 8-C-beta-D-glucopyranosyl-3',4',5,7-tetrahydroxyflavone, 5-methyl orientin, 7-methyl orientin, and 5,7-dimethyl orientin, respectively, are reported herein. The C-glucosyl phloroacetophenone derivatives were obtained via a regio- and stereoselective O-->C glycosyl rearrangement. Aldol condensation of the C-glucosyl phloroacetophenone derivatives with 3,4-bisbenzyloxybenzaldehyde afforded the corresponding C-glucosylchalcones. Construction of the flavone system by reaction with I(2)-Me(2)SO, followed by the elimination of the 5-benzyl protecting group in the flavone structure, yielded an orientin derivative and a isoswertiajaponin derivative. Methylation of the orientin derivatives with dimethyl sulfate afforded the parkinsonin A derivative, the isoswertiajaponin derivative, and the parkinsonin B derivative. Finally, hydrogenolysis of these C-glucosylflavone derivatives led to the four 8-C-glucosylflavones. The NMR spectra of these C-glucosylflavones showed a duplication of signals corresponding to a major rotamer, along with a minor one. Based on NOESY experiments in Me(2)SO at ambient temperature, they adopted conformations in which the H-2"and H-4" protons in the glucose moiety were oriented toward the B-ring in the flavone structure.
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Flavonoides/síntesis química , Glucósidos/síntesis química , Antioxidantes/síntesis química , Antioxidantes/química , Flavonoides/química , Glucósidos/química , Espectroscopía de Resonancia Magnética , Estructura Molecular , Plantas/químicaRESUMEN
The treatment of unprotected mono-C-beta-D-glucopyranosylphloroacetophenone with a cation-exchange resin in anhydrous acetonitrile afforded both a phloroacetophenone and a di-C-beta-D-glucopyranosylphloroacetophenone. Treatment of an unprotected mono-C-(2-deoxy-beta-D-arabino-hexopyranosyl)phloroacetophenone (mono-C-2-deoxy-beta-D-glucopyranosylphloroacetophenone) also afforded both the aglycon and di-C-(2-deoxy-beta-D-arabino-hexopyranosyl)phloroacetophenone. The reaction mixtures were acetylated, and the structures of the isolated products were determined by NMR spectroscopy. This is the first demonstration of the formation of a di-C-glycosyl compound during the chemical cleavage of the C-C linkage between the sugar and the aglycon in an aryl C-glycosyl derivative.
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Acetofenonas/química , Glicósidos/química , Carbono/química , Espectroscopía de Resonancia Magnética , Estructura MolecularRESUMEN
Glycosylation of the nitroxyl radicals, 4-acetoxy-2,2,6,6-tetramethylpiperidin-1-oxyl (4-acetoxy-TEMPO) and 3-carbamoyl-2,2,5,5-tetramethylpyrollin-1-oxyl (3-carbamoyl-PROXYL) with peracetylglycosyl fluoride as the glycosyl donor, in the presence of boron trifluoride diethyl etherate (BF(3) x OEt(2)) and an amine base afforded the corresponding hydroxylamine-O-glycosides in 25-100% yields.
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Óxidos N-Cíclicos/química , Fluoruros/química , Óxidos de Nitrógeno/química , Pirrolidinas/química , Marcadores de Spin/síntesis química , Aminas/química , Antioxidantes/química , Boranos/química , Radicales Libres/química , Glicósidos/química , Glicosilación , Estructura Molecular , Protectores contra Radiación/químicaRESUMEN
The reaction of 2,3,4-tri-O-benzyl-alpha-L-rhamnopyranosyl fluoride (6-deoxy-2,3,4-tri-O-benzyl-alpha-L-mannopyranosyl fluoride) with 2,4-dibenzylphloroacetophenone, in the presence of boron trifluoride.diethyl etherate, afforded both the 3-C-alpha-L- and the 3-C-beta-L-rhamnopyranosylphloroacetophenone derivatives. The 3-C-alpha-L-rhamnoside was produced as a major product, while the 3-C-beta-L-rhamnoside was produced as a minor product via anomerization of the 3-C-alpha-L-rhamnoside. Alternatively, the reaction of 2,3,4,6-tetra-O-benzyl-alpha-D-mannopyranosyl fluoride with 2,4-dibenzylphloroacetophenone afforded both the 3-C-alpha-D- and the 3-C-beta-D-mannnopyranosylphloroacetophenone derivatives under identical conditions. The 3-C-beta-D-mannoside was produced as a major product via anomerization of the 3-C-alpha-D-mannoside during the reaction. These differences in composition result apparently from the magnitude of the 1,3-diaxial interactions between the C-3 and C-5 positions in these sugar moieties.