Isolation and identification of a cis-C8-diol-ester of okadaic acid from Dinophysis acuta in New Zealand.

A cis-isomer of a C(8)-diol ester of okadaic acid (1) was isolated during large-scale purification of pectenotoxins (PTXs) from extracts of Dinophysis acuta collected from the west coast of South Island, New Zealand. The compound was identified by NMR spectroscopic and liquid chromatography-mass spectrometry (LC-MS) studies, and is the first reported cis-isomer of an okadaic acid C(8)-diol-ester identified in Dinophysis. The more abundant trans-C(8)-diol ester of okadaic acid (2) isolated from the same Dinophysis extract was rapidly hydrolyzed to okadaic acid in vitro by the supernatant from green-lipped mussel hepatopancreas.     

In vivo MR microscopy of the human skin

The requirements for imaging the skin are dictated by the organ's layered structure, which extends only a few millimeters from the surface and thus demands extremely high resolution in this direction. While less critical, resolution in the remaining two dimensions determines whether the skin's accessory structures can be resolved. The problem is compounded by short transverse relaxation times, in particular of the dermis, the structure of most clinical interest. In this work images of the normal human skin were obtained in vivo at voxel sizes as small as 19 × 78 × 800 μm³, by means of customized 3D gradient and partial flip-angle spin-echo pulse sequences and very small transmit/receive coils on a 1.5T clinical imager equipped with high-power whole-body gradients. Structures resolved include hair follicles and the sublayers of the dermis. The very short time constant for the major component (91 %) for transverse relaxation in the dermis (T₂* ～10 ms) suggests the potential of substantial gains in achievable signal-to-noise ratio by shortening the echo time.     

Synthesis,activity on NK‐3 tachykinin receptor and conformational solution studies of scyliorhinin II analogs modified at position 16

Abstract: Two analogs of a tachykinin family peptides – scyliorhinin II (ScyII): [Aib¹⁶]ScyII and [Sar¹⁶]ScyII were synthesized by the solid‐phase method using Fmoc chemistry. Conformational studies in water and DMSO‐d₆ on these peptides were performed using a combination of two‐dimensional NMR and theoretical conformational analysis. The solution structure of the peptides studied is interpreted as an equilibrium of several conformers with different statistical weights. The structure of [Sar¹⁶]ScyII in water appeared to be more flexible, especially in the C‐terminal fragment. A better defined structure for this analog was obtained in DMSO‐d₆, in which the analysis resulted in a family of conformers with similar shapes. Some of these conformers were characterized by the presence of a 3₁₀‐helix in the N‐terminal fragment and middle part of the molecule. The introduction of the Aib residue in position 16 significantly rigidifies the structure. For [Aib¹⁶]ScyII in both solvent systems very similar populations of conformations were obtained which are characterized by the presence of a 3₁₀‐helix in the 13–18 fragment. A common structural motif was found in conformationally constrained Cys⁷?Cys¹³ fragment, which resembles the Greek letter ‘ω’. The differences in the solution structure of the C‐terminal fragment of the peptides studied are responsible for their specificity. [Aib¹⁶]ScyII showed 25% the agonistic activity of selective NK‐3 agonist – senktide, but it also showed antagonist effect vs. this peptide, whereas [Sar¹⁶]ScyII appeared to be a full agonist of NK‐3 tachykinin receptor.     

The influence of dietary habits and pathological conditions on the binding of theophylline to serum albumin

The influence of fatty acids (FA) on theophylline (Th) binding to human serum albumin (HSA) in its high and low affinity binding sites was investigated. The content of studied FA solutions corresponds to the ones associating with different dietary habits and pathological states in vivo. Using fluorescence and ¹H NMR spectroscopy two high and two low affinity binding sites of Th in HSA structure were found. For each site several binding parameters in the absence and presence of FA were estimated. The results showed that the impact of FA on the affinity of HSA towards Th in high affinity binding sites is negligible whereas binding of the drug in low affinity sites decreases significantly in the presence of FA. It was observed that this effect is dependent on the number of fatty acid molecules bound to the protein while the chemical structure of fatty acids contained in the solution plays a minor role.     

Identification of the anabolic steroid 6β‐chlorotestosterone in a dietary supplement

Capsules that were labeled to be performance‐enhancing dietary supplements obtained during an investigation were found to contain an unrecognized steroid‐like substance. This compound was isolated by liquid chromatography (LC) fraction collection and characterized using several qualitative analytical techniques, including ultraviolet (UV) spectroscopy, gas chromatography–mass spectrometry (GC–MS), liquid chromatography‐high resolution accurate mass‐mass spectrometry (LC–HRAM–MS), as well as ¹H, ¹³C, and two‐dimensional nuclear magnetic resonance (NMR) spectrometry. This multi‐technique analytical approach was used to identify the designer steroid as 6β‐chloro‐4‐androsten‐17β‐ol‐3‐one (6β‐chlorotestosterone), an analog of testosterone about which little has been published.     

Interaction between paramagnetic metal complexes and intracellular water of single cells

Oocytes from Xenopus laevis were used as a well-established model to investigate spatially resolved changes in relaxation time (T1) within a cell during exposure to copper complexes by means of 'H-NMR-microscopy. T1 relaxation of intracellular water was shortened in dependence on the complex concentration, the water content, and the water mobility in various cell compartments. A relatively constant T1 decrease was observed in the cytoplasm of the vegetal pole, irrespective of the type and concentration of the permeable complexes used. Since the lowest content of free mobile water molecules was detected at the vegetal pole, we concluded that this quantity was as important for the relaxation time decrease as that of the chelated paramagnetic ions. Experiments using ¹⁴C-labeled inulin demonstrated that the paramagnetic metal complexes entered the oocytes without gross injury to their plasma membranes.     

头孢曲松钠中残留的三嗪环的定性与定量分析

目的控制头孢曲松钠中三嗪环的残留量,减少过敏反应的发生,促进工艺改进。方法作者采用MS、IR与NMR等波谱技术对制备的三嗪环(triazin)样品进行结构确认,用HPLC法对其进行纯度测定;根据欧洲药典方法,用质量分数为1.0%的头孢曲松钠对照液做对照,以头孢曲松钠供试液中三嗪环的峰面积与质量分数为1.0%的对照液中头孢曲松钠的峰面积比来计算三嗪环的含量。结果制备三嗪环样品的工艺能够获得目标产物,质量分数纯度为99.72%;三嗪环与头孢曲松的相对保留时间为0.59,其含量质量分数为0.099%。结论该方法适合头孢曲松钠中残留的三嗪环的定性定量分析,其含量在安全限度范围内(质量分数不超过1.0%),患者可以放心使用。     

Short-term changes in lipoprotein subclasses and C-reactive protein levels of hypertriglyceridemic adults on low-carbohydrate and low-fat diets

Diets designed to promote weight loss and improve atherogenic lipid profiles traditionally include a reduction in total fat and, in particular, saturated fats. This study was designed to test the efficacy of a low-fat diet vs a carbohydrate (CHO)–restricted (low-CHO) diet in hypertriglyceridemic patients on lipid profile, weight loss, high-sensitivity C-reactive protein (hs-CRP), and satiety. Twenty-eight hypertriglyceridemic subjects (based on fasting triacylglycerol [TG] levels exceeding 1.69 mmol/L) were randomized to either the low-CHO or low-fat diet for 8 weeks. Fasting bloods were acquired at weeks 0 and 8 and analyzed for lipids and hs-CRP. Body weight and other anthropometric measures were also obtained. Three random 24-hour food recalls were used to assess compliance during the trial and 2 recalls before randomization to permit individualized dietary education. A significant time-by-treatment interaction was observed (P = .045), wherein the small low-density lipoprotein cholesterol concentrations were reduced by 46% in the low-CHO–assigned subjects and increased by 36% for those assigned the low-fat plan. The observed decrease in TG (18%) among low-CHO subjects, in contrast to the 4% increase for low-fat group, was not significant, nor were there significant differences in hs-CRP, overall dietary compliance, satiety, or the magnitude of body weight loss between groups (low-CHO group, −3.8% vs low-fat group, −1.6%). Favorable reductions in small low-density lipoprotein concentrations after 8 weeks suggest that a moderately restricted carbohydrate diet (20% CHO as energy) can promote a less atherogenic lipid profile when compared to the low-fat diet.     

Lactam ergot alkaloids (ergopeptams) as predominant alkaloids in sclerotia of Claviceps purpurea from Norwegian wild grasses

Four major alkaloids in the extracts from sclerotia of Claviceps purpurea, picked from wild grasses, have been identified as lactam (non-cyclol) ergot alkaloids. The structural information was obtained from ion trap MS and NMR spectroscopy. The data for one of the lactam ergot alkaloids were coinciding with ergocristam [N-(lysergyl-valyl)-cyclo(phenylalanyl-prolyl)]. The structural information of two further lactam alkaloids was suggestive of either alpha- or beta-ergocryptam [N-(lysergyl-valyl)-cyclo(leucyl-prolyl) or N-(lysergyl-valyl)-cyclo(isoleucyl-prolyl)] and ergoannam [N-(lysergyl-leucyl)-cyclo(leucyl-prolyl) or N-(lysergyl-isoleucyl)-cyclo(isoleucyl-prolyl)]. The constitution of the fourth lactam ergot alkaloid corresponded to N-(lysergyl-isoleucyl)-cyclo(phenylalanyl-prolyl), a new ergopeptam, which has not been described before. Additionally, the cyclol-analogue of the new ergopeptam was detected in the extracts and has been identified on the basis of its product ion spectrum from fragmentation of [M+H](+). The study described in this paper shows that lactam ergot alkaloids may not only be minor products of ergopeptine biosynthesis, as has been suggested hitherto, but may be major biosynthetic endproducts for some ergot strains. This is also the first report demonstrating the production of an ergot alkaloid that contains isoleucine as the second amino acid, i.e. the N-(lysergyl-isoleucyl)-moiety, by parasitic, naturally growing C. purpurea. This unusual type of ergot alkaloid has so far only been found in saprophytic cultures of C. purpurea.     

代谢组学的研究现状与展望

代谢组学是20世纪90年代中期发展起来的对某一生物或细胞所有低相对分子质量代谢产物进行定性和定量分析的一门新学科,由于其广泛的应用前景,目前已成为系统生物学的重要组成部分。现简要介绍了代谢组学的含义、代谢组学研究的历史沿革、当前代谢组学研究中的分析技术、数据解析方法,综述了代谢组学在药物毒理学研究、疾病诊断、植物和中药等领域的应用情况,并对当前代谢组学研究中存在的问题及发展趋势进行探讨。