Structural determination of glucosylceramides isolated from marine sponge by fast atom bombardment collision‐induced dissociation linked scan at constant B/E

Five glucosylceramides (GlcCers) were isolated by reversed phase high‐performance liquid chromatography from the MeOH extracts of a marine sponge, Haliclona (Reniera) sp., collected from the coast of Ulleung Island, Korea, and analyzed by fast atom bombardment mass spectrometry (FAB–MS) in positive‐ion mode. FAB‐mass spectra of these compounds included protonated molecules [M + H]⁺ and abundant sodiated molecules [M + Na]⁺ from a mixture of m‐NBA and NaI. The structures of these GlcCers, which were similar, were elucidated by FAB‐linked scan at constant B/E. To find diagnostic ions for their characterization, the GlcCers were analyzed by collision‐induced dissociation (CID) linked scan at constant B/E. The CID‐linked scan at constant B/E of [M + H]⁺ and [M + Na]⁺ precursor ions resulted in the formation of numerous characteristic product ions via a series of dissociative processes. The product ions formed by charge‐remote fragmentation provided important information for the characterization of the fatty N‐acyl chain moiety and the sphingoid base, commonly referred to as the long‐chain base. The product ions at m/z 203 and 502 were diagnostic for the presence of a sodiated sugar ring and β‐D ‐glucosylsphinganine, respectively. For further confirmation of the structure of the fatty N‐acyl chain moiety in each GlcCer, fatty acid methyl esters were obtained from the five GlcCers by methanolysis and analyzed by FAB–MS in positive‐ion mode. On the basis of these dissociation patterns, the structures of the five GlcCers from marine sponge were elucidated. In addition, the accurate mass measurement was performed to obtain the elemental composition of the GlcCers isolated from marine sponge. Copyright © 2009 John Wiley & Sons, Ltd.     

Inside Cover: Self‐Template‐Directed Formation of Coordination‐Polymer Hexagonal Tubes and Rings,and their Calcination to ZnO Rings (Angew. Chem. Int. Ed. 8/2009)

Hexagonal tubes and rings with unusual shapes were generated through a unique self‐template‐directed growth mechanism. As described by M. Oh and co‐workers in the Communication on page 1459 ff., initially formed solid coordination polymer particles (CPPs) act as templates for the growth of the final hexagonal tubes and rings. Simple calcination of these unusually shaped CPPs results in the spontaneous formation of ZnO particles while the unique shape is maintained.

     

Cover Picture: Solid‐State Scrolls from Hierarchical Self‐Assembly of T‐Shaped Rod–Coil Molecules (Angew. Chem. Int. Ed. 9/2009)

Solid scrolls are reversibly formed by self‐assembly of rod‐shaped molecules with laterally attached coil units, in contrast to the layered structures formed from self‐assembly of planar molecules. As described by M. Lee and co‐workers in their Communication on page 1664 ff., the core structure of the scrolls, which are either filled cylinders or hollow tubes, can be controlled by variation of the length of the coil unit. The cover picture shows aligned tubular scrolls displaying well‐defined in‐plane ordering of the rod segments.

     

Mesoporous TiO2 nano networks: Anode for high power lithium battery applications

Anatase phase mesoporous TiO₂ with I41/amd space group was synthesized via the urea assisted hydrothermal method. The existence of mono phasic TiO₂ sub-microspheres of uniform particle size (ca. 400 nm) encompassing an average crystallite size of 14 nm was demonstrated using the XRD, FE-SEM and TEM analysis. Surface area of ca. 116.49 m²/g along with a pore size of 7 nm was calculated using the BET and adsorption isotherm measurements which authenticated the mesoporous nature of the synthesized material. Suitable calcination temperature for the better electrochemical property was established via the optimization process. Accordingly, the mesoporous TiO₂ calcined at 400 °C displayed improved cycleability with excellent rate capability ever reported, even at 20 C-rate of discharge. The reason for the superior rate capability is corroborated to the highly mesoporous nature of the TiO₂ sub-microspheres that has imparted desirable surface area apposite for enhanced ionic and electronic diffusion.     

Capacitance response of double-walled carbon nanotubes depending on surface modification

The capacitive behaviors of high-purity double-walled carbon nanotubes (DWNTs) were investigated before and after oxidation using nitric acid (HNO₃). The electrodes prepared from the HNO₃-oxidized DWNTs have exhibited higher capacitances than the pristine nanotube electrode in both aqueous and non-aqueous systems, despite the deterioration of their specific surface area after HNO₃ oxidation. The superiority of the HNO₃-oxidized DWNTs in capacitance properties is caused by the variations of surface wettability and the interstitial pore structure of nanotube bundles, which result from the introduction of polar oxygen functional groups onto the nanotube surface by HNO₃ oxidation.     

The Antimicrobial Activity,Mosquito Larvicidal Activity,Antioxidant Property and Tyrosinase Inhibition of Piper Betle

The essential oil and methanolic and aqueous extracts of Piper betle L. were assayed for their antimicrobial activity, mosquito larvicidal activity, antioxidant property and mushroom tyrosinase inhibition. The methanolic and aquaous extracts showed strong activity against the yeasts: C. albicans, and M. pachydermatis. The crude essential oil exhibited a broad‐spectrum strong antimicrobial activity against all test organisms. The strongest activity was observed against C. albicans, followed by S. aureus and M. pachydermatis. The chemical composition of the essential oil and its fractions was analyzed by GC/MS analysis. Eugenol (36.2%), chavibetol acetate (16.9%), 4‐allylphenyl acetate (9.4%) and 4‐allylphenol (7.2%) were the main components, comprising 69.7% of the oil. The fractionation of the essential oil gave two fractions. Fraction I was rich in eugenol (71.3%) and fraction II in eugenol (46.4%), chavibetol acetate (19.4%) and 4‐allylphenyl acetate (11.8%). The essential oil exhibited the mosquito larvicidal activity with 2 h and 24 h LD₅₀ value of 86 and 48 ppm, respectively. The methanolic extract of P. betle showed larvicidal activity with 2 h and 24 h LD₅₀ value of 153 and 125 ppm, respectively, whereas the aqueous extract showed slight active. The individual antioxidant assays such as DPPH scavenging activity, chelating effect of ferrous ions and reducing power have been used. P. betle showed remarkable antioxidant activity in DPPH and reducing power assays. The activity observed can be attributed to the presence of the phenolic compounds. The essential oil exhibited concentration‐dependent inhibition of mushroom tyrosinase, giving an IC₅₀ value of 126 ppm. The fraction I showed a strong inhibition of tyrosinase activity, giving an IC₅₀ value of 115 ppm. The presence of 4‐allylphenolic components in the essential oil may play an important role in the inhibition of tyrosinase. In conclusion, the results presented here show that Piper betle essential oil could be considered as a natural antimicrobial, mosquito larvicidal, antioxidant and tyrosinase inhibition source.     

Cover Picture: Toroidal Micelles of Uniform Size from Diblock Copolymers (Angew. Chem. Int. Ed. 25/2009)

Pure toroidal micelles of highly uniform shape and size are presented by T. Chang et al. in their Communication on page 4594 ff. The donut‐shaped micelles are prepared by spontaneous self‐assembly of a polyisoprene‐block‐poly(2‐vinylpyridine) copolymer, and are stable enough to act as a template for the growth of gold nanoparticles along the ring surface.