Separation of ethylene-norbornene copolymers using high performance liquid chromatography.

The elution behavior of ethylene-norbornene (EN) copolymers prepared with various catalysts was studied in selected binary solvent gradients using porous graphite (HypercarbTM) as stationary phase. It was found that the elution volumes of the EN copolymers correlated with their average norbornene content. For a series with norbornene content lower than 20 mol % the correlation was positive (i.e. increasing elution volumes with increasing norbornene content), whereas for a series with norbornene contents above 20 mol % it was negative (decreasing elution volumes with increasing norbornene content). It is known that EN copolymers have complicated microstructures that depend on norbornene content and the catalyst system used for synthesis. Thus, it is supposed that the opposing trends in the elution behavior of the EN copolymers are caused by differences in their microstructure, ultimately governed by the norbornene content. Our conclusions are supported by results from NMR spectroscopy, which revealed the microstructure, and differential scanning calorimetry (DSC).

Novel skeleton compound Allomyrinanoid A and two purine alkaloids from the adult of Allomyrina dichotoma L.

Three new compounds were isolated from the adult insect of Allomyrina dichotoma L. for the first time. A new skeleton compound is named as Allomyrinanoid A (1) originated from the familiar norbornane derivatives and two new compounds of purine alkaloid are named as adenine-9-methylaldehyde oxime B (2) and 6-N-methyleneimine-adenine-9-methylaldehyde oxime B (3). The compounds (2) and (3) are the tautomers of imine-enamine and creatively separated form the solvent using column chromatography method. The structures of all isolated compounds were established by spectroscopic methods including analyses of their 1D, 2D NMR and HRESI-MS data, and confirmed by comparison of the literature data. These new components displayed antibacterial activities against both Gram-positive and Gram-negative strain.

Supercritical CO2 extraction of volatile oils from Sardinian Foeniculum vulgare ssp. vulgare (Apiaceae): chemical composition and biological activity.

This article reports the results on the composition and antifungal effect of volatile extracts obtained from the aerial parts of Sardinian wild fennel (Foeniculum vulgare Mill.), by supercritical fluid extraction (SFE) and by hydrodistillation (HD). The extracts were analysed by gas chromatography-mass spectrometry for qualitative composition and gas chromatography-flame ionisation detector to establish the percentage of constituents. The main components were fenchone (7.1% vs. 8.8%), estragole (34.9% vs. 42.6%) and (E)-anethole (24.6% vs. 43.4%) in the SFE and HD extract, respectively. Minimum inhibitory concentrations (MICs) were measured according to the reference Clinical and Laboratory Standards Institute (CLSI) broth macrodilution protocols. Minimum lethal concentrations were determined by subsequent subculturing of the same cell suspensions in solid medium. The essential oil was more active against Candida albicans, whereas the supercritical fluid extract possesses higher activity against Candida guillermondii and Cryptococcus neoformans, with MIC values of 0.32 µL/mL.

Essential oil composition and enantiomeric distribution of fenchone and camphor of Lavandula cariensis and L. stoechas subsp. stoechas grown in Greece.

The essential oils from leaves and inflorescences of L. cariensis Boiss. and L. stoechas L. subsp. stoechas collected in Greece were analyzed by GC and GC/MS. In the inflorescences and leaves essential oils of L. cariensis the most abundant metabolite was camphor (51.8, 48.8% respectively), whereas in the essential oils of L. stoechas subsp. stoechas, the main constituents were fenchone (39.9, 21.0% respectively) and camphor (24.2, 26.3% respectively). Both enantiomers of camphor were present, whereas only (+) fenchone was detected.

Contact and fumigant activities of constituents of Foeniculum vulgare fruit against three coleopteran stored-product insects.

The insecticidal activities of materials derived from the fruit of fennel, Foeniculum vulgare, against adults of Sitophilus oryzae, Callosobruchus chinensis and Lasioderma serricorne were examined using direct contact application and fumigation methods. The biologically active constituents of the Foeniculum fruits were characterized as the phenylpropenes (E)-anethole and estragole, and the monoterpene (+)-fenchone, by spectroscopic analysis. Responses varied with insect species, compound, dose and exposure time. In a filter paper diffusion test, estragole at 0.168 mg cm-2 caused 91% mortality to S oryzae adults within 1 day after treatment (DAT), whereas (+)-fenchone and (E)-anethole gave over 90% mortality at 2 and 4 DAT, respectively. Against C chinensis adults, all test compounds revealed potent insecticidal activities at 0.021 mg cm-2 at 2 DAT. Against L serricorne adults at 0.105 mg cm-2, (E)-anethole gave 100% mortality at 1 DAT, whereas 90 and 60% mortality at 4 DAT was achieved with estragole and (+)-fenchone, respectively. In a fumigation test, the compounds were much more effective against adults of S oryzae, C chinensis and L serricorne in closed cups than in open ones, indicating that the insecticidal activity of test compounds was largely attributable to fumigant action. As naturally occurring insect-control agents, the F vulgare fruit-derived materials described could be useful for managing field populations of S oryzae, C chinensis and L serricorne.

Supercritical carbon dioxide extraction and fractionation of fennel oil.

Ground fennel seeds were extracted with supercritical carbon dioxide. Small-scale subsequent extractions of the same sample showed that the composition of volatile compounds was changed with the extension of extraction time and only principal volatile components (limonene, fenchone, methylchavicol, and anethole) were present in the last-extracted sample. Fennel oil was successfully fractionated into the essential oil rich and fatty oil rich products in pilot-scale apparatus using two separators in series. Designed experiments were carried out to map the effects of pressure and temperature in the first separator on the yields and compositions of the products. The minimum level of the total undesired components in both essential oil rich and fatty oil rich products appeared at a pressure of 80-84 bar and a temperature of 31-35 degrees C in the first separator. Supercritical CO(2) extraction of fennel seeds resulted in higher yield (10.0%) than steam distillation (3.0%), almost the same yield as hexane extraction (10.6%), and lower yield than alcohol extraction (15.4%). Analysis of the volatile compounds revealed the significant difference of the composition in distilled oil and oleoresins prepared by CO(2) and solvent extractions. Sensory evaluation showed that the CO(2) extraction product and distilled oil were more intense in odor and taste than alcohol and hexane extracts.

Chiral high-performance liquid chromatography of N-octyl bicycloheptene dicarboximide and confirmatory studies using liquid chromatography-tandem mass spectrometry and two-dimensional nuclear magnetic resonance spectroscopy.

N-Octyl bicycloheptene dicarboximide (MGK 264) has exo and endo diastereomers. Each structure has a chiral center at the nitrogen side chain. Enantioselective separation of MGK 264 was achieved by normal-phase high-performance liquid chromatography (HPLC) using cellulose-based Chiralcel OD column with diode-array and optical rotation detectors. Peaks were isolated with the purpose of identifying their stereochemical structures. Molecular mass of the HPLC peaks and their structural information was determined by liquid chromatography-electrospray tandem mass spectrometry (LC-ES-MS-MS). A two-dimensional nuclear magnetic resonance (NMR) spectroscopic technique was used to establish the structural features. Correlation of the data obtained from chiral separation and NMR facilitated in unambiguous assignment of the HPLC peaks.

Chemoenzymatic access to enantiomeric bicyclo[2.2.1]heptan-2,5-diones.

A practical integrated process, combining an enzymatic resolution step with a few chemical transformations, is described for the synthesis of (1R, 4R)- and (2S, 4S)-bicyclo[2.2.1]heptan-2,5-diones 1 of high enantiomeric purity, starting from a standard mixture of (+/-)-endo- and exo-2-acetoxy-5-norbornene.