Structural features of lignin macromolecules extracted with ionic liquid from poplar wood

1-Ethyl-3-methylimidazolium acetate ([Emim][CH?COO]) was used for the extraction of lignin from poplar wood (Populus albaglandulosa), which was called to ionic liquid lignin (ILL) and structural features of ILL were compared with the corresponding milled wood lignin (MWL). Yields of ILL and MWL were 5.8±0.3% and 4.4±0.4%, respectively. The maximum decomposition rate (V(M)) and temperature (T(M)) corresponding to V(M) were 0.25%/ °C and 308.2 °C for ILL and 0.30%/ °C and 381.3 °C for MWL. The amounts of functional groups (OMe and phenolic OH) appeared to be similar for both lignins; approximately 15.5% and 6.7% for ILL and 14.4% and 6.3% for MWL. However, the weight average molecular weight (M(w)) of ILL (6347 Da) was determined to be 2/3-fold of that of MWL (10,002 Da) and polydispersity index (PDI: M(w)/M(n)) suggested that the lignin fragments were more uniform in the ILL (PDI 1.62) than in the MWL (PDI 2.64).     

Regulation of Intracellular pH in Guinea Pig Cerebral Cortex Ex Vivo Studied by 31P and 1H Nuclear Magnetic Resonance Spectroscopy: Role of Extracellular Bicarbonate and Chloride

Abstract: The role of transmembrane processes that are dependent on external anions in the regulation of cerebral intracellular pH (pH_i), high-energy metabolites, and lactate was investigated using ³¹P and ¹H NMR spectroscopy in an ex vivo brain slice preparation. During oxygenated superfusion, removal of external HCO₃^?/CO₂ in the presence of Na⁺ led to a sustained split of the inorganic phosphate (P_i) peak so that the pH_i indicated by one part of the peak was 0.38 pH units more alkaline and by the other part 0.10 pH units more acidic at 5 min than in the presence of HCO₃^?. The pH in the compartment with a higher pH_i value returned to 7.29 ± 0.04 by 10.5 min of superfusion in a HCO₃^?-free medium, whereas the pH_i in an acidic compartment was reduced to 7.02. In the presence of 4,4′-diisothiocyanatostilbene-2,2′-disulfonic acid or the absence of external Cl^?, removal of HCO₃^? caused alkalinization without split of the P_i peak. Both treatments reduced the rate of pH_i normalization following alkalinization. Simultaneous omission of external HCO₃^? and Na⁺ did not inhibit alkalinization of the pH_i following CO₂ exit. All these data show that the acid loading mechanism at neutral pH_i is mediated by an Na⁺-independent anion transport. During severe hypoxia, pH_i dropped from 7.29 ± 0.05 to 6.13 ± 0.16 and from 7.33 ± 0.03 to 6.67 ± 0.05 in the absence and presence of HCO₃^?, respectively, in Na⁺-containing medium. Lactate accumulated to 18.7 ± 2.8 and 19.6 ± 1.5 mmol/kg under the respective conditions. In the HCO₃^?-free medium supplemented with 1 mM amiloride, the pH_i fell only to 6.94 ± 0.08 despite the lactate concentration of 18.9 ± 2.4 mmol/kg. Acidification caused by hypoxia was also small in the slice preparations superfused in the absence of both HCO₃^? and Cl^?, as the pH_i was 7.01 ± 0.12 at a lactate concentration of 24.5 ± 2.4 mmol/kg. These data indicate that apart from anaerobic glucose metabolism, separate acidifying mechanisms are functioning during hypoxia under these conditions. Recovery of phosphocreatine levels following reoxygenation was >75% relative to the prehypoxic level in the slice preparations superfused in the absence of HCO₃^? but <47% in those preparations superfused without HCO₃^? and Cl^?. This indicates that either neutral pH_i or absence of Cl^? during hypoxia was deleterious to the energy metabolism. The present data indicate that Cl^?/HCO₃^? exchange mechanisms have distinct roles in cerebral H⁺ homeostasis depending on the level of pH_i and energy state.     

A H NMR metabolic profiling to the assessment of protein tyrosine phosphatase 1B role in liver regeneration after partial hepatectomy

Protein tyrosine phosphatase 1B (PTP1B) is a negative regulator of the tyrosine kinase growth factor signaling pathway, which is involved in major physiological mechanisms such as liver regeneration. We investigate early hepatic metabolic events produced by partial hepatectomy (PHx) for PTP1B deficient (PTP1B KO) and wild type (WT) mice using proton nuclear magnetic resonance spectroscopy. Metabolic response of the two genotypes produced 24 h upon PHx is compared using magic angle spinning high-resolution nuclear magnetic resonance (¹H-HR-MAS-NMR) on intact liver tissues. In addition, genotype-associated metabolic profile changes were monitored during the first 48 h after PHx using high-resolution nuclear magnetic resonance (¹H-HR-NMR) on liver extracts. A marked increase of lipid-related signals in regenerating livers was observed after 24 h PHx in either intact tissues or liver extracts studies. In spite of this common initial metabolic response, results obtained 48 h after PHx on liver extracts indicate a genotype-differential metabolic pattern. This metabolic pattern resulted in line with well known regenerative features such as more sustained cell proliferation, a better management of lipids as energy fuel and lessened liver injury for PTP1B KO mice as compared to WT. Taken together, these findings suggest the metabolic basis to the pivotal role of PTP1B in liver regeneration.     

Physiological variation in metabolic phenotyping and functional genomic studies: use of orthogonal signal correction and PLS-DA

Metabolic phenotyping, or metabotyping, is increasingly being used as a probe in functional genomics studies. However, such profiling is subject to intrinsic physiological variation found in all animal populations. Using a nuclear magnetic resonance-based metabonomic approach, we show that diurnal variations in metabolism can obscure the interpretation of strain-related metabolic differences in two phenotypically normal mouse strains (C57BL10J and Alpk:ApfCD). To overcome this problem, diurnal-related metabolic variation was removed from these spectral data by application of orthogonal signal correction (OSC), a data filtering method. Interpretation of the removed orthogonal variation indicated that diurnal-related variation had been removed and that the AM samples contained higher levels of creatine, hippurate, trimethylamine, succinate, citrate and 2-oxo-glutarate and lower levels of taurine, trimethylamine-N-oxide, spermine and 3-hydroxy-iso-valerate relative to the PM samples. We propose OSC will have great potential removing confounding variation obscuring subtle changes in metabolism in functional genomic studies and will be of benefit to optimising interpretation of proteomic and genomic datasets.     

日本续断中新五糖皂甙的结构及其核磁共振光谱

从日本续断（Ｄｉｐｓａｃｕｓ ｊａｐｏｎｉｃｕｓ Ｍｉｑ．）根的乙醇提取物中分得一个新的三萜皂甙,其结构被鉴定为３．－Ｏ－〖β－Ｄ－吡喃葡萄糖（１→）〗〖α－吡喃鼠李糖（１→３）〗－β－Ｄ－吡喃葡萄３９糖（１→３）－α－Ｌ吡喃鼠李糖（１→２）－α－吡喃阿拉伯糖－齐墩酸。采用一维ＳＥＭＤＹ谱和转坐标ＮＯＥ差谱核磁共振新技术相结合的方法,对糖体间和９糖体与甙元间的连接顺连接位置进行了研究。该方法的结果