Identifying bryostatins and potential precursors from the bryozoan Bugula neritina

The bryozoan species Bugula neritina contains the anticancer agent bryostatin. Bryostatin has been extracted from these sessile marine invertebrates since the late 1960s from the Gulf of California, Gulf of Mexico, as well as various locations on the eastern and western rims of the Pacific Ocean. In this work we are focusing on animals harvested in the Gulf of Mexico near Alligator Point (Florida). Using Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) we measure the concentration of 70 elements in B. neritina, a sea squirt, and the sediment from the point of harvesting. This data has helped us generate an extraction process for marine natural products. Combining UV/VIS absorbance measurements with Matrix Assisted Laser Desorption Ionization-Time of Flight-Mass Spectrometer (MALDI-TOF-MS), we demonstrated that the specific form of bryostatin extracted is a function of the solvent. A 9.4T Fourier Transform-Ion Cyclotron Resonance (FT-ICR) mass spectrometer, whose sensitivity, mass accuracy, and resolving power allowed the exact empirical formulas of potential precursors of bryostatin to be identified, was employed. Finally we examine extracts of 14 marine species of the Gulf of Mexico, from the sand trout (Cynoscion arenarius) to chicken liver sponge (Chrondrilla nucula), all recently collected, which had shown some medicinal activity thirty years ago in a National Cancer Institute study. By the MALDI-TOF-MS, we were able to identify mass spectral features that correspond to different variations of the basic bryostatin structure, which raises the question if the bryozoans are the original source of bryostatin.     

Naturally occurring esterification reactions with bryostatin

Bryostatin structures share a commonality of a central bryophan ring, but each differs due to two groups (R(1) and R(2)) that are attached to the bryophan ring via ester bonds. This research examines the impact that conditions such as UV light, acidic and basic conditions can have on the bryostatin structure in the presence of octanoic acid and water. Mass spectrometry (MS) measurements suggest that bryostatin can easily rearrange into various structures under natural conditions by reacting with carboxylates that are ubiquitous in nature. A second set of measurements suggest bryostatin can be hydrolyzed by water, a reaction that has significant implications in both medicinal applications and extraction procedures.     

bryA: an unusual modular polyketide synthase gene from the uncultivated bacterial symbiont of the marine bryozoan Bugula neritina

"Candidatus Endobugula sertula," the uncultivated bacterial symbiont of Bugula neritina, is the proposed source of the bryostatin family of anticancer compounds. We cloned a large modular polyketide synthase (PKS) gene complex from "Candidatus Endobugula sertula" and characterized one gene, bryA, which we propose is responsible for the initial steps of bryostatin biosynthesis. Typical PKS domains are present. However, acyltransferase domains are lacking in bryA, and beta-ketoacyl synthase domains of bryA cluster with those of PKSs with discrete, rather than integral, acyltransferases. We propose a model for biosynthesis of the bryostatin D-lactate starter unit by the bryA loading module, utilizing atypical domains homologous to FkbH, KR, and DH. The bryA gene product is proposed to synthesize a portion of the pharmacologically active part of bryostatin and may be useful in semisynthesis of clinically useful bryostatin analogs.     

高效液相色谱-质谱法鉴定总合草苔虫中的草苔虫内酯成分

采用高效液相色谱分离与质谱检测的联用技术,对总合草苔虫中的草苔虫内酯成分进行定性分析。在以体积比为80∶20的甲醇-水溶液为流动相、采用ODS柱进行分离的色谱条件下,10种草苔虫内酯成分均可获得良好的分离。分析结果表明：深圳大亚湾产地的总合草苔虫中共含有9种已知和1种未知的草苔虫内酯成分。已知成分分别是bryostatin 4,5,6(9),7,8,10,16,17,18,其中bryostatin 7和17是首次从中国海域总合草苔虫中发现的2种痕量草苔虫内酯。该方法简便、准确、灵敏度高,可以很好的对总合草     

Antineoplastic agents 100: The marine bryozoan Amathia convoluta

An intensive investigation of the marine animal AAmathia convoluta (Bryozoa phylum) for antineoplastic constituents has led to the isolation and structural determination of bryostatin 8 (2). A total of 100 kg of Amathia convoluta was required to obtain some 4.2 mg of bryostatin 8. Evaluation of bryostatin 8 against the murine P388 lymphocytic leukemia showed substantial inhibition of growth (PS, cell line ED₅₀, 1.3 × 10^-3, T/C 174 at 0.11 $\text{mg}\text{kg}$). A major part of the very strong antineoplastic activity exhibited by fractions prepared from Amathia convoluta was accounted for by the isolation of bryostatins 4 (1a), 5 (1c) and 6 (1b). All three bryostatins were obtained in yields comparable to that of bryostatin 8 and appear derived from the closely related marine bryozoan Bugula neritina. The epiphytic-like relationship of Bugula neritina to Amathia convoluta is discussed.     

Computational studies of Fe(III) binding to bryostatins, bryostatin analogs, siderophores and marine natural products: arguments for ferric complexes in medicinal applications

In this computational study, geometric factors are calculated by applying semi-empirical methods (PM3) that support experimental evidence from this lab where bryostatins can bind trivalent iron with six Fe-O bonds forming an octahedral geometry. The geometric factors are calculated for all 20 structures (Fe3+ bound to bryostatin 1-20) as a neutral, monovalent, and divalent species. The average Fe-O bond distances and bond angles are compared to those of known marine and terrestrial siderophores. From these two data sets, we then examined other known marine natural products (MNPs) that can form a hexavalent complex with six Fe-O bonds and draw conclusions about their potential biological role as marine siderophores. This computational data indicates that Fe(III) strongly bonds to a host of MNPs, increasing their water solubility, contracting their structure, hence allowing transport through cell membranes more readily, and in some cases, stabilizing ester bonds that are susceptible to hydrolysis. It is argued that administering medicinally bryostatin, its analogs or other MNPs as a ferric complex, holds some fundamental chemical advantages compared to its administration as a neutral uncomplexed species.     

金丝矮陀陀植物中甾体生物碱的分离与化学结构

最近,我们研究了云南产的金丝矮陀陀植物中的甾体生物碱。对植物样品的乙醇提取物作了系统分离,从中得到22个甾体生物碱,     

可紫外光固化的聚乙烯基硅氮烷合成与表征

采用带丙烯酸酯基团的烯丙基溴化合物(4-溴丁烯酸乙酯)和聚乙烯基硅氮烷发生取代反应,实现了丙烯酸酯基团在聚乙烯基硅氮烷主链上的链接.采用质子核磁共振谱(1H-NMR)和二维质子核磁共振谱(2D-1H-1H-NMR)对分子结构进行了表征,采用光学差热分析仪(Photo-DSC)和傅立叶转换红外光谱仪(FT-IR)测试了改性高分子的光敏性能,用热重分析仪(TGA)分析了产物在高纯氮气氛围下的陶瓷收率.结果表明,通过分子改性,交联固化时间从改性前的20min减少到1min之内,功能化的聚乙烯基硅氮烷可以在光刻蚀工艺中作为负性光刻胶使用.     

Synthesis of a simplified bryostatin C-ring analogue that binds to the CRD2 of human PKC-alpha and construction of a novel BC-analogue by an unusual Julia olefination process

[structure: see text] The synthesis of two truncated bryostatin analogues 2 and 3 is described. High-field NMR measurements on the C-ring analogue 3 in C(2)H(3)CN containing 25% (2)H(2)O have shown that it binds to the CRD2 of human PKC-alpha at virtually the same position as phorbol-13-acetate (PA) and bryostatin 1 (1). NMR titration studies have also revealed that 3 binds to the CRD2 with a potency similar in magnitude to PA but much less potently than 1.     

Enantioselective formal total synthesis of the antitumor macrolide bryostatin 7

A new enantioselective synthesis of Masamune's AB fragment (1) for bryostatin 7 is described. Key steps in the new route include a Meerwein-Ponndorf-Verley reduction to set the O(7) stereocenter and an alkylative union between the dithiane 6 and iodide 5 to construct the C(9)-C(10) bond. Because we have previously published a synthesis of Masamune's C-ring phenyl sulfone 2, our new route to 1 constitutes a formal total synthesis of bryostatin 7; it also corrects the previously reported spectral data for 1 in CDCl3.     

Naturally occurring organic matter as a chemical trap to scan an ecosystem for natural products

A model is proposed that tests an ecosystem for natural products (NPs) using a nonpolar extract of naturally occurring organic matter (NOM), which we demonstrate to be an efficient chemical trap for relatively nonpolar organic molecules. To test the model we collected twenty-six samples of NOM from various locations on the Suwannee River, from its headwaters in the Okeefenokee Swamp to the Gulf of Mexico. We have tentatively identified stearic acid, DDT, chincodine, and a potential precursor to bryostatin. Our data provide evidence that NOM can trap, hold for several decades, concentrate, and transport NP in the environment.     

南海软珊瑚Sarcophyton molle化学成分的研究

从中国南海软肉芝软珊瑚(Sarcophyton molle)中分离到七个化合物, 经紫外光谱(UV), 红外光谱(IR), 质谱(MS)和核磁共振光谱(1H NMR, 13C NMR)分析, 确定了其化学结构。它们是: 异新西松烯(1), (E, E, E)-7, 8-环氧-1-异丙基-4, 8, 12-三甲基-十四环-1,3, 11-三烯(2), 正十八烷酸(3), 鲨肝醇(4), 神经酰胺(5), 胸腺嘧啶(6), 胸腺嘧啶脱氧核苷(7)。其中化合物(2)为新化合物。本文是第一次报道软珊瑚Sarcophyton molle的化学成分。     

A Raman spectroscopic study of indolinium steryl dyes

Resonance Raman spectra have been obtained in the region 400–1700 cm⁻¹ for several indolinium steryl dyes under various experimental conditions. The changes in vibrational frequencies have been correlated with changes in the UV—vis absorption maxima observed previously and which are due to solvent polarity variations, the complexation of the dye molecules containing a crown ether ring with Mg²⁺, and the variations in molecular structure. Preliminary assignments of the observed bands to particular vibrations are made.     

Photopolymerisation of composite material in simulated free space environment at low Earth orbital flight

Inflatable Gossamer’s structures which can be deployed in Earth orbit have great prospects in the future. Material for use in inflatable structures must be soft before and during unfolding and harden after unfolding. The best way for solidification of Gossamer’s structures is by chemical polymerisation of a composite material in space environment. The polymerisation processes of liquid polymer matrix in a free space environment are sensitive to microgravitation, temperature variations (−150 to +150 °C), high vacuum (10⁻³ to 10⁻⁷ Pa), atomic oxygen flux (in LEO), UV and VUV irradiations, X-ray and γ-irradiations, high energy electron and ion fluxes. In this paper experiments of the photopolymerisation processes under simulated free space conditions were carried out. The influences of high vacuum, temperature variations, high energy ion beam, radio-frequency and microwave plasma on polymerisation of UV-curing resin were observed. The effects of low molecular components evaporations, acceleration of curing kinetics, additional chemical reactions and mixing processes during polymerisation were observed. The photopolymerisation of inflatable structure was carried out under simulated temperature conditions of space flight in low Earth orbit. The results indicate a technology for large-size inflatable constructions in Earth orbit, in far space and on space bodies as for deployed antennas, solar sail stringers, solar shield stringers, frames for large-size space stations, frames for Moon, Mars, asteroids bases and frames for space plant on Earth orbit and other celestial bodies.     

Die vermutliche Struktur der Anodendroside. Glykoside und Aglykone, 331. Mitteilung

Five crystalline compounds (anodendrosides) have been isolated from Anodendron paniculatum (Roxb.)A. DC. (Apocynaceae). They represent glycosides containing unusual sugars. Tentative structures for anodendroside-A ( 155 ), ?E₁ ( 3 ), ?E₂ ( 84 ), ?F ( 144 ) and ?G ( 115 ) are now presented. These structures are based on UV., IR., but mostly on high resolution mass spectra. NMR.-spectra could be performed with A, O-acetyl-E₂ and O-acetyl-G, which are in good agreement with the suggested structures. The unusual methylendioxy group postulated in the sugar moiety of A, E₁ and E₂ was also established by chemical methods, yielding approximately 1 Mol. equiv. of formaldehyde after acid hydrolysis of anodendroside-E₂.     

Synthesis of Octylmethoxycinamate-silica Core-shell Nanoparticles with Self-templating Method

A self-templating method was employed to synthesize core-shell nanoparticles with octylmethoxycinamate(OMC), a well-known organic UV absorber, as core and nanosilica particles as shell. The characteristic of this method is that the whole process requires neither surface treatment for nanosilica particles nor additional surfactant or stabilizer, and all the reactions could be finished in one-pot, which exempts removing template and reduces reaction steps compared to the conventional process. The morphology, structure, particle size distribution, chemical composition and optical property of OMC-SiO2 nanoparticles were characterized by scanning electron microscopy(SEM), transmission electron microscopy(TEM), dynamic light scattering(DLS), FTIR spectrometry and UV absorption spectrometry, respectively. Experiment results indicate that the resulting OMC-SiO2 nanoparticles were perfectly spherical with smooth particle surfaces, and had clear core-shell structures. The particle size could be tuned by altering reaction conditions. In addition, the mechanism of the self-templating method for forming core-shell nanoparticles was discussed.     

The practical synthesis of a novel and highly potent analogue of bryostatin

Macrocycle 1 is a new highly potent analogue of bryostatin 1, a promising anti-cancer agent currently in human clinical trials. In vitro, 1 displays picomolar affinity for PKC and exhibits over 100-fold greater potency than bryostatin 1 when tested against various human cancer cell lines. Macrocycle 1 can be generated in clinically required amounts by chemical synthesis in only 19 steps (LLS) and represents a new clinical lead for the treatment of cancer.     

Conformational rearrangements by water-soluble peptoid foldamers

Peptoids are a family of N-substituted glycine oligomers that are capable of forming stable helical structures. We seek peptoid monomers that can establish a strong folding propensity in aqueous conditions. Here we utilize L-phenylalanine tert-butyl ester as a readily available reagent for the synthesis of (S)-N-(1-carboxy-2-phenylethyl)glycine oligomers. The products form stable secondary structures in aqueous solution in which the conformation is dramatically responsive to variations in pH and solvent composition.     

尾式卟啉-5-氟尿嘧啶及其金属络合物的光谱分析

合成了24种新型的尾式卟啉-5-氟尿嘧啶化合物及其金属锰络合物,通过核磁共振氢谱（NMR）、质谱（MS）、红外光谱（IR）、紫外光谱（UV）及元素分析确定了其结构,并讨论了24种化合物光谱的关系特征及其规律,确定卟啉类配体与金属络合的NMR、IR、UV判据。     

From nanoplates to microtubes and microrods: a surfactant-free rolling mechanism for facile fabrication and morphology evolution of Ag2S films

By a simple and facile wet-chemistry technique without any surfactant, various shapes of Ag(2)S crystals--including leaflike pentagonal nanoplates, crinkly nanoscrolls, hexagonal prismlike microtubes, and microrods--were fabricated in situ on a large-area silver-foil surface separately. Detailed experiments revealed that the Ag(2)S nanoplates were formed just by immersing the silver foil in a sulfur/ethanol solution at room temperature and atmospheric pressure, and they subsequently rolled into nanoscrolls and further grew into microtubes and microrods under solvothermal conditions. Inspired by the natural curling of a piece of foliage, we proposed a surfactant-free rolling mechanism to interpret the observed morphological evolution from lamellar to tubular structures. Based on these simple, practical, and green chemical synthetic routes, we can easily synthesize lamellar, scrolled, tubular, and clubbed Ag(2)S crystals by simply adjusting the reaction temperature, pressure, and time. It is very interesting to note that the current rolling process is quite different from the previous reported rolling mechanism that highly depends on the surfactants; we revealed that the lamellar Ag(2)S could be rolled into tubular structures without using any surfactant or other chemical additives, just like the natural rolling process of a piece of foliage. Therefore, this morphology-controlled synthetic route of Ag(2)S crystals may provide new insight into the synthesis of metal sulfide semiconducting micro-/nanocrystals with desired morphologies for further industrial applications. The optical properties of the pentagonal Ag(2)S nanoplates/film were also investigated by UV/Vis and photoluminescence (PL) techniques, which showed large blue-shift of the corresponding UV/Vis and PL spectra.