The Total Synthesis of Brevetoxin B: A Twelve-Year Odyssey in Organic Synthesis

The total synthesis of brevetoxin B has been achieved recently after a long search for a suitable pathway. This twelve-year odyssey

1 The Odyssey of Homer, translated by R. Lattimore, Harper Perenial, New York, 1975 . Homer's Odyssey, one of the western world's first two poems (the Iliad is the other), is the tale of the adventures, wanderings, and exploits of Odysseus, a Greek hero of the Trojan war, as he attempts to reach Ithaca, his home island where his wife Penelope awaits him. During his journey Odysseus has an incredible series of adventures and setbacks caused by the anger of the god Poseidon, whose son Odysseus had blinded. Finally, assisted by his patroness, the goddess Athene, Odysseus returns home to Ithaca to find and punish the suitors, evil men who tried to win his wife's hand and who squandered his wealth and corrupted his servants while he was away. Telemachus, Odysseus' son, who had his own share of adventures while growing up, facing the suitors and, looking for his father, joins him in glory and wisdom as they reestablish their throne on Ithaca. Besides Odysseus, other main characters of Odyssey are as follows: Telemachus: The son of Odysseus, who is just entering manhood, is highly conscious of his duties as a prince successor to the throne and protector of his mother as well as the need to live up to his father's reputation as a hero. His actions waver between the immature and the well-thought over as he searches for the truth about his father and desperately appeals to others for help. It is not until towards the end of the story that he exhibits great courage, skills, and confidence and one feels that he is, indeed, the son of Odysseus. Athene: She is the daughter of Zeus, goddess of wisdom, and patroness of arts and crafts. Odysseus is her favorite and protegé and she is his heroine, even though she is a goddess. She plays a leading role in all important events in the narrative, and her spirit and power always influence and assist Odysseus and Telemachus in their difficult moments. A friend and a confidant to Odysseus, she enjoys winning him over and her relationship with him, while the hero adores her and finds special comfort, companionship, and understanding in her. Poseidon: Younger brother to Zeus, god of the sea and of earthquakes, father of Polyphenus the one-eyed Cyclops whom Odysseus blinds. As a ruler of the sea and natural phenomena, Poseidon is able to place many obstacles in front of Odysseus, whom he despises. Poseidon, however, is unable to hold out against the combined pressure of the other gods, particularly Athene, of whom Odysseus is a favorite, and so eventually relents, but not before he repeatedly unleashes his anger. The Cyclops, Scylla, and The Sirens: Some of the superhuman and monstrous characters of the tale who inflicted tremendous tortures and blows at Odysseus and his men, before he finally overcame them. The Suitors: The evil noblemen of Ithaca who attempt to undermine Odysseus, win the hand of his queen, Penelope, and corrupt his palace servants. They succeed partly, wasting away a great deal of Odysseus fortune, but he eventually prevails and punishes them. Ithaca: The island kingdom of Odysseus, most likely located somewhere off the western coast of Greece and the destination of the hero in this adventure. It is interesting to compare places, events, and characters from the Odyssey to those of modern-day total synthesis, an excercise left to the imagination of the reader!

in synthetic organic chemistry was marked by several strategic and tactical routes, and resulted in numerous new synthetic methods. This article is a behind-thescenes account of the total synthesis of brevetoxin B, from its origins at the University of Pennsylvania to its completion at the University of California, San Diego, and The Scripps Research Institute, La Jolla, California.     

Application of proteomics for determining protein markers for wool quality traits

The technique of two-dimensional electrophoresis (2-DE) has been under investigation for its usefulness in identifying protein markers for wool quality traits in sheep. However, before this could be achieved, unique problems relating to the detection and quantitation of wool proteins needed to be overcome so that 2-DE protein maps could be examined using computational programs like Melanie II. Four protein staining regimes were examined. Colloidal Coomassie Blue G-250 was found to be superior to Coomassie Blue R-250 and gave satisfactory staining of all protein classes. Silver staining detects minor strings of keratinous proteins, but unfortunately it negatively stains intermediate filament proteins, the major high sulphur proteins (HSPs) and the high glycine tyrosine proteins and the latter two classes can only be seen by overstaining the background of the gel. In contrast, labeling reduced keratins with [14C]iodoacetamide, followed by autoradiography detection, results in a protein map with low background and all protein spots stained positively. 2-DE has been used to obtain wool protein maps of Lincoln/Merino chimeric sheep to examine wool originating from two genotypes grown with different crimp frequencies within the same fleece. Between fleece, variations have also been examined. Work to date suggests that several major HSPs may be associated with the fibre curvature trait known as crimp frequency. From matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectral mapping, one of these proteins has been identified as being from the B2A family from the HSP class.     

IgA肾病免疫吸附剂的研究(Ⅲ)

在碱性条件下,用环氧氯丙烷对琼脂糖载体进行活化,并通过戊二醛法引入手臂,偶联羊抗人IgA的抗体,清除IgA肾病病人体内高含量的IgA分子,从而达到治疗病症的目的.通过体外实验发现,新研制的免疫吸附剂最高吸附率可以达到70%左右.     

How Thiostrepton Was Made in the Laboratory

Thiostrepton, a powerful antibiotic belonging to the thiopeptide class, was synthesized in the laboratory for the first time in 2004 through an arduous campaign involving novel strategies and tactics, scenic detours, and unexpected roadblocks. In this Review the author narrates the long journey to success, not so dissimilar to Odysseus’ return voyage to Ithaca, full of adventure, knowledge, and wisdom.

1 Inspired by the writing form of Mahaffy, 1 the author has taken liberties with the style in which this Review is written.

     

Prototropy,Intramolecular Interactions,Electron Delocalization,and Physicochemical Properties of 1,8-dihydroxy-9-anthrone—DFT-D3 Study of Substituent Effects

1,8-dihydroxy-9-anthrone are tricyclic compounds with a ketone group in the middle ring and two hydroxyl groups substituted in the side-aromatic rings what results in formation of two intramolecular hydrogen bonds in which the oxygen atom from the ketone group is the proton acceptor. 1,8-dihydroxy-9-anthrones in which intramolecular proton transfer between C10 and CO in the middle ring occurs, can exist in a tautomeric keto-enol equilibrium. For anthralin, the most important representative of this group, this equilibrium has been studied previously, but it has not been studied for its derivatives. Substituents in the middle ring change the geometry of 1,8-dihydroxy-9-anthrones so they are also expected to affect the keto-enol equilibrium. It is also important to study the effect of intramolecular hydrogen bonds on the structure of both tautomeric forms. It was found that the nature of the substituent in the middle ring could affect the antioxidant properties of the investigated compound.     

The combined use of size-exclusion and reversed-phase high-performance liquid chromatography for characterization of beta-endorphin processing pathways

A method is described for the separation and analysis of multiple molecular forms of immunoreactive beta-endorphin and its alpha-N-acetylated congeners by a combination of reversed-phase and size-exclusion high-performance liquid chromatography coupled with two specific radioimmunoassays. Both chromatographic procedures are fast (less than 50 min per analysis) providing good resolution and high recovery (greater than 90%). The solvents used in both systems are ultraviolet transparent (less than 214 nm), non-corrosive, low salt (less than 0.05 M) and after evaporation fully compatible with subsequent radioimmunoassay. We have evaluated these techniques using both synthetic and purified peptide standards and have applied these procedures to characterize immunoreactive beta-endorphin and alpha-N-acetylendorphin in rat and sheep pituitary extracts, and the low levels found in sheep hypothalamus and rat ovary. These chromatographic procedures are not only applicable to the study of pro-opiomelanocortin-derived peptides, but also could be employed to examine the processing pathways of other biologically active polypeptides, in both central and peripheral tissue extracts.     

Off-Flavor Removal from Sheep Placenta via Fermentation with Novel Yeast Strain Brettanomyces deamine kh3 Isolated from Traditional Apple Vinegar

Animal placentae can be used as health-promoting food ingredients with various therapeutic efficacies, but their use is limited by their unpleasant odor and taste. This study aimed to investigate the possibility of deodorization of sheep placenta via yeast fermentation. A yeast strain was successfully isolated and identified as a novel Brettanomyces strain (Brettanomyces deamine kh3). The deodorizing efficacy of fermentation of the sheep placenta with B. deamine kh3 was evaluated by 42 panels, based on evaluation of preference, ranking, and aroma profiles, and compared with normal placenta and placenta fermented with B. bruxellensis. The results of the sensory evaluation indicated that fermentation of the sheep placenta with B. deamine kh3 may improve its palatability by increasing flavors such as that of grass (tree), rubber, and burnt, and by decreasing the odor and soy sauce flavor. Solid-phase microextraction-gas chromatography (SPME-GC) showed that major off-flavors in sheep placenta, such as ammonia, dimethyl disulfide, and 1,3-dioxolane, were completely diminished in the sheep placenta fermented with B. deamine kh3. This study presents those major volatile compounds, including 2-isobutyl\-4,4-dimethyl-1,3-dioxane, and 3-methyl-1-butanol, could be crucial in improving the palatability of the sheep placentae fermented with B. deamine kh3. This study provides a good starting point for the industrial application of a new deodorization method.     

Arthur von Weinberg: Chemiker,Naturforscher

The chemist Dr. Arthur von Weinberg was a member of the Cassella – Gans – Weinberg families of traders and industrialists. In close cooperation with his uncle, Dr. Leo Gans, and his brother, Carl von Weinberg, he developped the small dyestuff factory of his uncle into the world's largest azodyestuff fabrication site of the end of the 19^th century. This was achieved by scientifically exploring the chemistry of naphthalene and its derivatives and exploiting their commercial potential as dyestuff precursors. Furthermore, Dr. Arthur von Weinberg realized the market opportunities of sulfur dyes, which could be manufactured in large volumes at low cost. Most important, he very early recognized the great importance of synthetic pharmaceuticals. In 1908 he and his brother Carl were ennobled for their scientific and economic achievements; his hometown Frankfurt/Main made Arthur von Weinberg a “Honorary Citizen” in 1930. Imprisoned based on his jewish background by the Nazi‐government he died in the concentration camp of Theresienstadt in 1943.     

Paracelsus,a Transmutational Alchemist

A scholarly consensus has long held that in redefining alchemy, Paracelsus rejected metallic transmutation. I show here, however, that for most of his career Paracelsus believed that it was possible to change one metal into another, and even late in his short life he did not break with that view. Furthermore, in certain places in his works he also represented himself, occasionally directly and more often obliquely, as a practical transmutationist. Because Paracelsus not only acknowledged that metallic transmutations were theoretically possible but also claimed to have carried them out in practice, we must regard him as (among other things) a transmutational alchemist. As such, he had more in common than historians have generally admitted with both his medieval predecessors and his posthumous followers. The Paracelsian alchemists of the late-sixteenth and seventeenth centuries were not wrong to situate Paracelsus within the alchemical tradition, nor to connect their own goldmaking interests to his.     

Otto Roelen,Pioneer in Industrial Homogeneous Catalysis

Otto Roelen discovered the oxo synthesis (hydroformylation) in 1938, and despite all the problems created by the war years he was able to explore successfully the fundamental aspects related to its application up to the point of building the first plant. At the same time he laid the groundwork for industrial utilization of homogeneous organometallic catalysts. Almost simultaneously, his contemporary, Walter Hieber, was investigating the basic chemistry of the same catalysts, but with no knowledge whatsoever of their potential application. Hydroformylation today constitutes one of the most important industrial examples of a homogeneous catalytic process. For corrigendum see DOI: 10.1002/anie.199423481     

Chemical imaging of articular cartilage sections with Raman mapping, employing uni- and multi-variate methods for data analysis

Raman mapping in combination with uni- and multi-variate methods of data analysis is applied to articular cartilage samples. Main differences in biochemical composition and collagen fibers orientation between superficial, middle and deep zone of the tissue are readily observed in the samples. Collagen, non-collagenous proteins, proteoglycans and nucleic acids can be distinguished on the basis of their different spectral characteristics, and their relative abundance can be mapped in the label-free tissue samples, at so high a resolution as to permit the analysis at the level of single cells. Differences between territorial and inter-territorial matrix, as well as inhomogeneities in the inter-territorial matrix, are properly identified. Multivariate methods of data analysis prove to be complementary to the univariate approach. In particular, our partial least squares regression model gives a semiquantitative mapping of the biochemical constituents in agreement with average composition found in the literature. The combination of hierarchical and fuzzy cluster analysis succeeds in detecting variations between different regions of the extra-cellular matrix. Because of its characteristics as an imaging technique, Raman mapping could be a promising tool for studying biochemical changes in cartilage occurring during aging or osteoarthritis.     

The Introduction of a Cysteine Residue Modulates The Mechanical Properties of Aromatic-Based Solid Aggregates and Self-Supporting Hydrogels

Peptide-based hydrogels, originated by multiscale self-assembling phenomenon, have been proposed as multivalent tools in different technological areas. Structural studies and molecular dynamics simulations pointed out the capability of completely aromatic peptides to gelificate if hydrophilic and hydrophobic forces are opportunely balanced. Here, the effect produced by the introduction of a Cys residue in the heteroaromatic sequence of (FY)3 and in its PEGylated variant was evaluated. The physicochemical characterization indicates that both FYFCFYF and PEG8-FYFCFYF are able to self-assemble in supramolecular nanostructures whose basic cross-β motif resembles the one detected in the ancestor (FY)3 assemblies. However, gelification occurs only for FYFCFYF at a concentration of 1.5 wt%. After cross-linking of cysteine residues, the hydrogel undergoes to an improvement of the rigidity compared to the parent (FY)3 assemblies as suggested by the storage modulus (G’) that increases from 970 to 3360 Pa. The mechanical properties of FYFCFYF are compatible with its potential application in bone tissue regeneration. Moreover, the avalaibility of a Cys residue in the middle of the peptide sequence could allow the hydrogel derivatization with targeting moieties or with biologically relevant molecules.     

限制在疏水板中的新的六边形-四边形三层冰结构

对限制在两个光滑的疏水板间的水进行了分子动力学模拟,观察到了两种晶体结构,都满足冰规则．在1GPa的压强和1．0nm的板间距下获得的新的冰相是平坦的六边形-四边形三层冰．在此结构中,靠近板的两层（外层）中的水分子形成六边形环,中间层的水分子形成四边形环．对于外层的水分子,其四个氢键中的三个在同一层中,另一个氢键与中间层连接．对于中间层的水分子,四个氢键中的两个在同。层中,而另外两个氢键与两个不同的外层相连．虽然三层的形状不同,但其面密度却接近相等．另一种结构是在0．8nm的板问距和100MPa的侧向压下获得的平坦的六边形双层冰．模拟中的相变既有一阶相变,也有连续相变．     

Nortestosterone: endogenous in urine of goats, sheep and mares?

For a number of species it is known that nortestosterone, either the alpha- or beta-epimer, can be of endogenous origin. For goats and mares similar results have not yet been published. As a follow-up on the experiments with cattle, a large number of urine samples per animal were collected from pregnant goats, sheep and mares. These samples were analysed for the presence of alpha- and beta-nortestosterone and alpha-estradiol using GC-MS. The results show that in the goats and mares studied alpha-nortestosterone is present during pregnancy. In this study no alpha-nortestosterone could be demonstrated in sheep. From our study and recently published data, however, it is proven that alpha-nortestosterone can occur endogenously.     

Chirality in supramolecular self-assembled monolayers of achiral molecules on graphite: formation of enantiomorphous domains from arachidic anhydride

The molecular arrangement and chirality of the self-assembled arachidic anhydride monolayer on graphite were investigated using scanning tunneling microscopy (STM). This molecule has two identical alkyl chains, linked by an anhydride group in the middle. In its extended form, one alkyl chain is shifted, with respect to the other, along the molecular backbone. Upon adsorption on graphite, this achiral anhydride spontaneously forms two types of homogeneous domains (denoted as m and m') with mirror symmetry. The angle from the molecular chain to the row-packing direction is 98.0 degrees +/- 0.5 degrees and 82.0 degrees +/- 0.5 degrees for domains m and m', respectively. Domain m is the mirror image of m'. The molecular arrangement of this self-assembled monolayer shows that domains m and m' are two-dimensional enantiomers with opposite chiralities. This new molecular packing motif is confirmed by line-profile analyses along the molecule-chain and the row-packing directions. This finding demonstrates the spontaneous formation of highly ordered homogeneous enantiomorphous domains on graphite resulting only from weak van der Waals forces between the achiral arachidic anhydride molecules.     

Photoswitchable, DNA-Binding Helical Peptides Assembled with Two Independently Designed Sequences for Photoregulation and DNA Recognition

Diarylethene-bridged peptides were developed to photoregulate biomolecular interactions. The peptides are made up of diarylethene-bridged and DNA-binding regions at their N- and C?termini, respectively. The two regions could be independently designed and combined as desired. The α-helicities of the peptides were photoregulated in on/off or off/on manners, and the manner depended on the positions of two ornithine (Orn) residues for cross-linking reaction at the diarylethene-bridged region. In the case of the on/off manner, when the diarylethene structure adopted the open form on the peptides, the peptides folded into stable α-helices. Upon UV irradiation, the diarylethene moiety isomerized to its closed form to destabilize the helical structures. Quartz crystal microbalance (QCM) analysis showed that the open isomer strongly associated with a target DNA, as compared with the closed one. When the closed-form peptide existing in the DNA complex was irradiated with a fluorescent lamp in the middle of the QCM monitoring, the frequency change (ΔF) was enhanced by the diarylethene photoisomerization.     

Development of a surface plasmon resonance-based assay for the detection of Corynebacterium pseudotuberculosis infection in sheep

Caseous lymphadenitis (CLA), a disease affecting sheep and goats, is caused by Corynebacterium pseudotuberculosis and is difficult to detect, especially at early stages in its development. A surface plasmon resonance-based biosensor assay for the detection of antibodies to the phospholipase D (PLD) exotoxin of C. pseudotuberculosis in sheep serum was successfully generated. It employed a recombinant form of PLD, which was immobilised, and all aspects of the assay including minimisation of non-specific binding, and the regeneration of the chip, were optimised. The applicability of the assay was initially demonstrated using sera collected from experimentally infected sheep and from sheep with no prior history of infection. The assay was then evaluated on a panel of clinical samples and the results obtained compared very favourably to those obtained by a double sandwich ELISA (over 90% similarity) and clearly verified its analytical value.     

Lactoferrin from human breast milk and from neutrophil granulocytes. Comparative studies of isolation, quantitation, characterization and iron binding properties

The isolation and properties of lactoferrin from human breast milk and from neutrophilic granulocytes were investigated. Human breast milk lactoferrin was purified by means of heparin-sepharose or Cibacron Blue affinity chromatography. Quantitative recovery using these two methods was comparable but Cibacron Blue affinity chromatography allowed for isolation of a more homogenous protein. Lactoferrin could only be isolated from human neutrophilic granulocytes by sequential use of antibody affinity followed by non-specific affinity chromatography. Both breast milk lactoferrin and granulocyte lactoferrin were separated into apo and iron-rich species by SDS polyacrylamide gel chromatography. Iron binding is accompanied by a conformational change in tertiary structure associated with more rapid electrophoretic migration. The isoelectric point of both human breast milk lactoferrin and human granulocyte lactoferrin is 5.5-6.2. Both types of lactoferrin have similar iron binding properties with release of iron from the one binding site occurring at pH 5.2-6.0 while the other binding site holds on to iron down to pH 3.6-3.2. Despite the high affinity for iron the percentage saturation of native lactoferrin is low, that for breast milk lactoferrin averaging 12-25% and that for granulocyte lactoferrin less than 10%.     

Development and validation of a liquid chromatography and ion spray tandem mass spectrometry method for the quantification of artesunate, artemether and their major metabolites dihydroartemisinin and dihydroartemisinin-glucuronide in sheep plasma

Recently, promising fasciocidal activities of artesunate and artemether were described in rats and sheep. Therefore, a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed to quantify artesunate, artemether and their metabolites dihydroartemisinin and dihydroartemisinin-glucuronide in sheep plasma. Protein precipitation with methanol was used for sample workup. Reversed-phase high-performance liquid chromatography (HPLC) was performed using an Atlantis C18 analytical column with a mobile phase gradient system of ammonium formate and acetonitrile. The analytes were detected by MS/MS using selected reaction monitoring (SRM) with electrospray ionisation in the positive mode (transition m/z 267.4 → 163.0). The analytical range for dihydroartemisinin, dihydroartemisinin-glucuronide and artesunate was 10-1000 ng/ml and for artemether 90-3000 ng/ml with a lower limit of quantification of 10 and 90 ng/ml, respectively. Inter- and intra-day accuracy and precision deviations were < 10%. Consistent relative recoveries (60-80%) were observed over the investigated calibration range for all analytes. All analytes were stable in the autosampler for at least 30 h (6 °C) and after three freeze and thaw cycles. The validation results demonstrated that the LC-MS/MS method is precise, accurate and selective and can be used for the determination of the artemisinins in sheep plasma. The method was applied successfully to determine the pharmacokinetic parameters of artesunate and its metabolites in plasma of intramuscularly treated sheep.     

Preparation of a chemiluminescent imidoester for the non-radioactive labelling of proteins.

A chemiluminescent aryl acridinium ester was synthesized which possesses an imidate ester group capable of reacting with proteins under mild conditions. The compound can be detected at levels as low as 5.2 x 10(-19) mol using commercially available luminometers and can therefore be used to produce high specific activity labelled antibodies for use in immunochemiluminometric assays. The imidate ester compares favourably with a previously reported N-succinimidyl ester in terms of its labelling properties but is easier to synthesize, requiring one less step. The compound was used to label affinity purified to synthesize, requiring one less step. The compound was used to label affinity purified sheep antibodies to human parathyroid hormone to demonstrate its utility in a two-site immunochemiluminometric assay for the measurement of intact parathyroid hormone.