(E)-2,6,10-Trimethyldodec-8-en-2-ol: An Undescribed Sesquiterpenoid from Copaiba Oil

The use of copaiba oil has been reported since the 16th century in Amazon traditional medicine, especially as an anti-inflammatory ingredient and for wound healing. The use of copaiba oil continues today, and it is sold in various parts of the world, including the United States. Copaiba oil contains mainly sesquiterpenes, bioactive compounds that are popular for their positive effect on human health. As part of our ongoing research endeavors to identify the chemical constituents of broadly consumed herbal supplements or their adulterants, copaiba oil was investigated. In this regard, copaiba oil was subjected to repeated silica gel column chromatography to purify the compounds. As a result, one new and seven known sesquiterpenes/sesquiterpenoids were isolated and identified from the copaiba oil. The new compound was elucidated as (E)-2,6,10-trimethyldodec-8-en-2-ol. Structure elucidation was achieved by 1D- and 2D NMR and GC/Q-ToF mass spectral data analyses. The isolated chemical constituents in this study could be used as chemical markers to evaluate the safety or quality of copaiba oil.     

A remark on the fundamental lemma of Jacquet

We conjecture a generalization of the fundamental lemma of Jacquet in the context of ${\mathit{GL}}_n$ over a quadratic extension. We provide a heuristic argument for our expectation and prove our conjecture for ${\mathit{GL}}_2$. To cite this article: O. Offen, C. R. Acad. Sci. Paris, Ser. I 342 (2006).     

Flavonoid glycosides and methylinositol from Ebenus haussknechtii

Two flavonoid glycosides (compounds 1 and 3) of which one is reported for the first time and a methylinositol (compound 2) were isolated from the aerial parts of Ebenus haussknechtii (Leguminosae). The structures were established as quercetin-7-O-[alpha-L-rhamnopyranosyl(1 --> 6)-beta-D-galactopyranoside] (1), morin-3-O-[4-[5-(4-hydroxyphenyl)pentanoyl]-alpha-L-rhamnopyranosyl(1 --> 6)-beta-D-galactopyranosyl]-7-4'-di-O-methyleter (3), and methylinositol (2) on the basis of chemical and spectroscopic means. The antimicrobial activities of the extracts have also been examined.     

Effect of elevated concentrations of strontium and iron on the structural and dielectric characteristics of Ba(1−x−y)Sr(x)Ti Fe(y)O3 prepared through sol–gel technique

Nano-composite Ba_1−xSr_(x)TiO₃ (BST), where x=0.01–0.50 and doped with different concentrations of iron Ba_(1−x−y)Sr_(x)TiFe _(y)O₃ (BSTF), where x=0.01 and y=0.01–0.05 powders were prepared by sol–gel method.     

Novel poly(ethylene glycol) monomers bearing diverse functional groups

Poly(ethylene glycol) (PEG) mono methacrylate ester (MAPEG) has been used, through a variety of reactions, to form several novel monomers, bearing both a polymerizable handle and various functional groups. These new compounds may be conjugated to biomolecules via amine, acid, or thiol moieties or they may form dendrimers via the epoxide. In addition, polymerization of these monomers may result in functionalized nanoparticles and microparticles or coatings, thus altering the acid‐base or electrochemical properties of surfaces and particles. Full synthetic considerations, including interesting intermediates, are reported. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

State-of-the-art separation of ginsenosides from Korean white and red ginseng by countercurrent chromatography

Ginseng (Panax ginseng C. A. Meyer) has been one of the most popular herbs used for nutritional and medicinal purposes by the people of eastern Asia for thousands of years. Ginsenosides, the mostly widely studied chemical components of ginseng, are quite different depending on the processing method used. A number of studies demonstrate the countercurrent chromatography (CCC) separation of ginsenosides from several sources; however, there is no single report demonstrating a one-step separation of all of these ginsenosides from different sources. In the present study, we have successfully developed an efficient CCC separation methodology in which the flow-rate gradient technique was coupled with a new solvent gradient dilution strategy for the isolation of ginsenosides from Korean white (peeled off dried P. ginseng) and red ginseng (steam-treated P. ginseng). The crude samples were initially prepared by extraction with butanol and were further purified with CCC using solvent gradients composed of methylene chloride–methanol–isopropanol–water (different ratios, v/v). Gas chromatography coupled with flame ionization detector was used to analyze the components of the two-phase solvent mixture. Each phase solvent mixture was prepared without presaturation, which saves time and reduces the solvent consumption. Finally, 13 ginsenosides have been purified from red ginseng with the new technique, including Rg₁, Re, Rf, Rg_2, Rb₁, Rb₂, Rc, Rd, Rg₃, Rk₁, Rg₅, Rg₆, and F₄. Meanwhile, eight ginsenosides have been purified from white ginseng, including Rg₁, Re, Rf, Rh_1, Rb₁, Rb₂, Rc, and Rd by using a single-solvent system. Thus, the present technique could be used for the purification of ginsenosides from all types’ ginseng sources. To our knowledge, this is the first report involving the separation of ginsenoside Rg₂ and Rg₆ and the one-step separation of thirteen ginsenosides from red ginseng by CCC.     

Chemoselective Suzuki–Miyaura cross-coupling reactions of methyl 4-bromo-3-(trifluoromethylsulfonyloxy)-2-naphthoate

Arylated naphthalenes were prepared by Suzuki–Miyaura cross-coupling reactions of methyl 4-bromo-3-(trifluoromethylsulfonyloxy)-2-naphthoate. The reactions proceeded with very good chemoselectivity in favor of the triflate group, due to additive electronic ortho electronic effects.     

Synthesis and characterization of Na2O–CaO–SiO2 glass–ceramic

The Na₂O–CaO–SiO₂ ternary glass–ceramic with the composition of 49 mass% Na₂O, 20 mass% CaO, and 31 mass% SiO₂ was prepared by the conventional method. The ternary glass–ceramic was characterized using X-ray diffraction (XRD), differential thermal analysis (DTA), thermogravimetric analysis, Fourier transform infrared spectroscopy, and scanning electron microscopy techniques. The Na₂CaSiO₄ phase, having the cubic crystal system, with the crystallite size of 25.14 nm and lattice parameter of 0.7506 nm was determined from the XRD pattern. The activation energy of the glass–ceramic calculated from the DTA curves was found to be 162.02 kJ mol^?1. The Avrami exponent was found to be ~2 indicating a one-dimensional growth process. The mass loss percent from ambient temperature to 1,173 K is less than 1 %. The density was calculated to be 2,723 kg m^?3. The fine-grained microstructure with the particle sizes less than 1 μm was confirmed by the scanning electron microscope micrograph.     

Induction of Secondary Structure through Micellization of an Oppositely Charged Pair of Homochiral Block‐ and Homopolypeptides in an Aqueous Medium

Polyion complex (PIC) formation is an attractive method for obtaining molecular assemblies owing to their facile fabrication process in aqueous media, but more insights are required in order to control the higher‐dimensional structures of polypeptide‐based PICs. Herein, the PIC formation behavior of oppositely charged homochiral polypeptides, poly‐l ‐lysine and poly(ethylene glycol)‐b‐poly(l ‐glutamate) (PEG‐PLG), and their secondary structures are carefully studied in water. PIC formation takes place in a polymer concentration‐dependent manner, and clear β‐sheet formation is observed at polymer concentrations ≥0.3 mg mL⁻¹. The results also confirm that multimolecular aggregation is a prerequisite for β‐sheet formation, which indicates that the inner hydrophobic environment of PICs is favorable for β‐sheet formation. Furthermore, the PEG weight fraction, stereoregularity of the polypeptide, and ionic strength of the solutions are found to be key factors for generating a secondary structure, presumably because these factors can contribute to the tuning of the inner environment of PICs. This method of producing water‐soluble nanoassemblies from oppositely charged polypeptides may expedite self‐assembly studies in biological systems and be incorporated into various molecular systems to exploit protein‐mimicking features.