Zoanthus kuroshio is a colorful zoanthid with a fluorescent pink oral disc and brown tentacles, which dominates certain parts of the Taiwanese and Japanese coasts. This sea anemone is a rich source of biologically active alkaloids. In the current investigation, two novel halogenated zoanthamines [5α-iodozoanthenamine (1) and 11β-chloro-11-deoxykuroshine A (2)], along with four new zoanthamines [18-epi-kuroshine A (3), 7α-hydroxykuroshine E (4), 5α-methoxykuroshine E (5), and 18-epi-kuroshine E (6)], and six known compounds were isolated from Z. kuroshio. Compounds 1 and 2 are the first examples of halogenated zoanthamine-type alkaloids isolated from nature. Compounds 3 and 6 are the first zoanthamine stereoisomers with a cis-junction of the A/B rings. All isolated compounds were evaluated for their anti-inflammatory activities by measuring their effects on superoxide anion generation and elastase release by human neutrophils in response to fMLP.
Double-helix molecules are frequently encountered in biological and synthetic organic systems, where they typically provide improved strength and better electrical properties relative to materials containing linear chains or single helices. DNA is the defining example. A purely inorganic double helix has been hard to come by, until now.
A team of some 20 researchers led by Tom Nilges of the Technical University of Munich has prepared the first completely inorganic substance, SnIP, featuring a well-defined double-helix structure. This semiconducting material consists of a twisted tin iodide (SnI+) chain intertwined with a twisted phosphide (P–) chain. The team prepared gram amounts of SnIP by heating tin, red phosphorus, and tin tetra-iodide together (Adv. Mater.2016, DOI: 10.1002/adma.201603135).
Chemists have been seeking out inorganic double helices for decades. Researchers have reported X-ray crystal structures of bulk LiP and LiAs containing spiral and coaxial chains, but it remained unclear as to whether they should be called double-helix structures. More recently, researchers have attempted making metal or metal salt double-helix materials using nanotubes or DNA as templates. But a non-templated, carbon-free example with a fully characterized double-helix structure had remained elusive.
Centrifugal partition chromatography (CPC) and all countercurrent separation apparatus provide chemists with efficient ways to work with complex matrixes, especially in the domain of natural products. However, despite the great advances provided by these techniques, more efficient ways of analyzing the output flow would bring further enhancement. This study describe a hyphenated approach made by coupling NMR with CPC through a hybrid-indirect coupling made possible by using a solid phase extraction (SPE) apparatus intended for high-pressure liquid chromatography (HPLC)-NMR hyphenation. Some hardware changes were needed to adapt the incompatible flow-rates and a reverse-engineering approach that led to the specific software required to control the apparatus. 1D 1HNMR and 1H–1H correlation spectroscopy (COSY) spectra were acquired in reasonable time without the need for any solvent-suppression method thanks to the SPE nitrogen drying step. The reduced usage of expensive deuterated solvents from several hundreds of milliliters to the milliliter order is the major improvement of this approach compared to the previously published ones.
Jonathan Bisson†, Marion Brunel†, Alain Badoc†‡, Grégory Da Costa†‡, Tristan Richard†‡, Jean-Michel Mérillon†‡, and Pierre Waffo-Téguo*†‡
The sugar subunits of natural glycosides can be conveniently determined by acid hydrolysis and 1H NMR spectroscopy without isolation or derivatization. The chemical shifts, coupling constants, and integral ratios of the anomeric signals allow each monosaccharide to be identified and its molar ratio to other monosaccharides to be quantified. The NMR data for the anomeric signals of 28 monosaccharides and three disaccharides are reported. Application of the method is demonstrated with the flavonoid glycoside naringin (1), the aminoglycoside antibiotics kanamycin (2) and tobramycin (3), and the saponin digitonin (4).
Phytosterols are plant compounds that resemble animal cholesterol and perform similar functions in plant life. These substances can only enter the body through dietary sources, unlike cholesterol which is produced within the body itself.
Plant sterols, including beta sitosterol, are an effective natural supplement for maintaining healthy cholesterol. By inhibiting the absorption of cholesterol from the intestinal tract, plant sterols actually help block cholesterol from being absorbed into the bloodstream. Sterols have been shown to reduce total and LDL cholesterol by up to 15 percent.
A dichloromethane-soluble fraction of the stem bark of Conchocarpus fontanesianus showed antifungal activity against Candida albicans in a bioautography assay. Off-line high-pressure liquid chromatography activity-based profiling of this extract enabled a precise localization of the compounds responsible for the antifungal activity that were isolated and identified as the known compounds flindersine (17) and 8-methoxyflindersine (18). As well as the identification of the bioactive principles, the ultra-high-pressure liquid chromatography–high-resolution mass spectrometry metabolite profiling of the dichloromethane stem bark fraction allowed the detection of more than 1000 components. Some of these could be assigned putatively to secondary metabolites previously isolated from the family Rutaceae. Generation of a molecular network based on MS2 spectra indicated the presence of indolopyridoquinazoline alkaloids and related scaffolds. Efficient targeted isolation of these compounds was performed by geometric transfer of the analytical high-pressure liquid chromatography profiling conditions to preparative medium-pressure liquid chromatography. This yielded six new indolopyridoquinazoline alkaloids (5, 16, 19–22) that were assigned structurally. The medium-pressure liquid chromatography separations afforded additionally 16 other compounds. This work has demonstrated the usefulness of molecular networks to target the isolation of new natural products and the value of this approach for dereplication. A detailed analysis of the constituents of the stem bark of C. fontanesianus was conducted.
Rodrigo Sant’Ana Cabral†‡, Pierre-Marie Allard‡, Laurence Marcourt‡, Maria Cláudia Marx Young†, Emerson Ferreira Queiroz*‡, and Jean-Luc Wolfender‡
Previously, we showed a few examples of preparing crude extracts from plants and other organisms. While sometimes (rarely) we get lucky and obtain an extract that is predominantly one compound, a more representative situation is that a mixture of compounds is obtained.
Genome mining of the fungus Mucor irregularis (formerly known as Rhizomucor variabilis) revealed the presence of various gene clusters for secondary metabolite biosynthesis, including several terpene-based clusters. Investigation into the chemical diversity of M. irregularis QEN-189, an endophytic fungus isolated from the fresh inner tissue of the marine mangrove plant Rhizophora stylosa, resulted in the discovery of 20 structurally diverse indole-diterpenes including six new compounds, namely, rhizovarins A–F (1–6). Among them, compounds 1–3 represent the most complex members of the reported indole-diterpenes. The presence of an unusual acetal linked to a hemiketal (1) or a ketal (2 and 3) in an unprecedented 4,6,6,8,5,6,6,6,6-fused indole-diterpene ring system makes them chemically unique. Their structures and absolute configurations were elucidated by spectroscopic analysis, modified Mosher’s method, and chemical calculations. Each of the isolated compounds was evaluated for antitumor activity against HL-60 and A-549 cell lines.
Shu-Shan Gao†‡, Xiao-Ming Li†, Katherine Williams‡, Peter Proksch*§, Nai-Yun Ji*⊥, and Bin-Gui Wang*†
My children are currently 7-, 6-, and 4-years-old … and they love chemistry.
Now, if they were in a public school setting, they would have to wait to learn chemistry.
As I’ve mentioned before, I’m not a fan of making children wait to learn.
I’ve had several readers inquire about our other chemistry materials, so I felt a post was warranted. Today, I’m sharing chemistry resources kids love, and then I’d love to know your family’s favorites!
Researchers have discovered a new 3D structure that divides space into 24 regions, and have shown that it is the best solution yet to a modified version of a geometrical space-partitioning problem that has challenged researchers for more than a century.
In 1887, Lord Kelvin asked how space could be partitioned into 3D structures of equal volume in a way that minimizes the total surface area of each structure. It must be possible to tightly pack many of these structures together with no gaps in between them—in other words, they must be "space-filling" structures. Each structure can take on a variety of complex 3D shapes, or "polyhedra," either as a single polyhedron or a combination of multiple smaller polyhedra of various types. The challenge is to figure out what particular types of polyhedra to use in order to minimize the outer surface area of the entire structure.
Kelvin's best solution to this problem was a single polyhedron called a "tetrakaidecahedron," which has 14 faces: six squares and eight hexagons. Since this is the shape obtained when cutting the corners off a 3D diamond shape, it can also be thought of as a truncated octahedron.
"PDF Viewer is a free application, available for iOS and Android mobile devices, that allows users to view and annotate PDFs with ease. PDF viewer is unique in that it allows users to edit documents, e.g. delete pages, rotate pages, and add images and notes, and even add signatures, on any mobile device. Users can also easily check out a list of all recent annotations and edits, facilitating easy collaboration. PDF Viewer will be of use to anyone looking to quickly and easily collaborate on documents, and may prove especially helpful for the classroom or office."
The development of new antimalarial compounds remains a pivotal part of the strategy for malaria elimination. Recent large-scale phenotypic screens have provided a wealth of potential starting points for hit-to-lead campaigns. One such public set is explored, employing an open source research mechanism in which all data and ideas were shared in real time, anyone was able to participate, and patents were not sought. One chemical subseries was found to exhibit oral activity but contained a labile ester that could not be replaced without loss of activity, and the original hit exhibited remarkable sensitivity to minor structural change. A second subseries displayed high potency, including activity within gametocyte and liver stage assays, but at the cost of low solubility. As an open source research project, unexplored avenues are clearly identified and may be explored further by the community; new findings may be cumulatively added to the present work.
Alice E. Williamson†, Paul M. Ylioja†, Murray N. Robertson†, Yevgeniya Antonova-Koch§, Vicky Avery∥, Jonathan B. Baell⊥, Harikrishna Batchu#, Sanjay Batra#, Jeremy N. Burrows¶, Soumya Bhattacharyya#, Felix Calderonα, Susan A. Charman⊥, Julie Clarkβ, Benigno Crespoα, Matin Dean†, Stefan L. Debbertγ, Michael Delvesδ, Adelaide S. M. Dennisϵ, Frederik Derooseζ, Sandra Duffy∥, Sabine Fletcher∥, Guri Giaeverη, Irene Hallyburtonθ, Francisco-Javier Gamoα, Marinella Gebbiaη, R. Kiplin Guyβ, Zoe Hungerford†, Kiaran Kirkϵ, Maria J. Lafuente-Monasterioα, Anna Leeη, Stephan Meister§, Corey Nislowη, John P. Overingtonι, George Papadatosι, Luc Patinyκ, James Phamλ, Stuart A. Ralphλ, Andrea Rueckerδ, Eileen Ryan⊥, Christopher Southanμ, Kumkum Srivastava#, Chris Swainν, Matthew J. Tarnowski†, Patrick Thomsonξ, Peter Turner†, Iain M. Wallaceι, Timothy N. C. Wells¶, Karen White⊥, Laura White†, Paul Willis¶, Elizabeth A. Winzeler§, Sergio Wittlinπ, and Matthew H. Todd*†
Earlier this week, Oxford's Bodleian Library announced that it had digitized a 550 year old copy of the Gutenberg Bible along with a number of other ancient bibles, some of them quite beautiful. Not to be outdone, the British Library came out with its own announcement on Thursday:
"You know what STEM is right? Science, technology, engineering and math. These are skills that kids really need to have a nice handle on- both boys and girls. We incorporate STEM into our homeschooling as much as possible.
Let me show you how we took the parts from an old broken toy and turned it into a motorized coloring machine. My kids call this coloring of the future!"
ROCKETS are the thrilling, spectacular bit of space flight. But without something useful to carry they are basically just fireworks. To get a sense of the new entrepreneurial approach to unearthly enterprise, start instead with the radical changes in what it takes to make a spacecraft.
Four bicyclic and three pentacyclic guanidine alkaloids (1–7) were isolated from a French Polynesian Monanchora n. sp. sponge, along with the known alkaloids monalidine A (8), enantiomers 9–11 of known natural product crambescins, and the known crambescidins 12–15. Structures were assigned by spectroscopic data interpretation. The relative and absolute configurations of the alkaloids were established by analysis of 1H NMR and NOESY spectra and by circular dichroism analysis. The new norcrambescidic acid (7) corresponds to interesting biosynthetic variation within the pentacyclic core. All compounds exhibited antiproliferative and cytotoxic efficacy against KB, HCT116, HL60, MRC5, and B16F10 cancer cells, with IC50 values ranging from 4 nM to 10 μM.
Amr El-Demerdash†‡, Céline Moriou†, Marie-Thérèse Martin†, Alice de Souza Rodrigues-Stien†, Sylvain Petek§, Marina Demoy-Schneider⊥, Kathryn Hall∥, John N. A. Hooper∥#, Cécile Debitus§, and Ali Al-Mourabit*†
A tree's leaf, a blade of grass, a single algal cell: all make fuel from the simple combination of water, sunlight and carbon dioxide through photosynthesis. Now scientists say they have replicated—and improved on—that trick with their own “bionic leaf.”
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