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排序方式: 共有108条查询结果,搜索用时 15 毫秒
61.
62.
Thymus capitatus growing wild in Sardinia showed different essential oil composition if grown surrounding Cagliari than in north Sardinia. Here we verify the composition and antimicrobial activity of the oil to make it suitable for the cosmetic and confectionery industries. With the aim of improving the scent and the antimicrobical activity of T. capitatus essential oil, a hydroformylation reaction was carried out to transform the unsaturated components of the oil into the corresponding aldehydes. The essential oil of T. capitatus exhibited a significant antibacterial activity (MIC 0.125-0.5 mg/mL), and was also found effective on C. albicans (MIC 0.125 mg/mL). After hydroformylation, several new irregular terpenoid aldehydes were detected. The perfume of the new terpenic-like aldehydes is very agreeable and, therefore, the acceptability of the aroma is remarkably improved, but the antimicrobial activity was not increased. 相似文献
63.
We present an experiment where Ramsey-type spectroscopy is applied to autoionizing states of krypton by using the ninth harmonic (88 nm) of a femtosecond Ti:sapphire laser. The ionization process, detected by an electron-energy spectrometer, shows the characteristic quantum interference pattern. The behavior of the fringe contrast compares favorably with a simple essential-state model, whose parameters have been taken from the literature. The experiment shows the feasibility of high-resolution spectroscopy in the extreme ultraviolet by using high-order laser harmonics. 相似文献
64.
The occurrence of iridoid glycosides in a number of Cymbalaria spp. collected in Italy is shown and chemosystematic implications are discussed. 相似文献
65.
Maria Bellumori Marzia Innocenti Federica Congiu Gabriele Cencetti Aida Raio Felicia Menicucci Nadia Mulinacci Marco Michelozzi 《Molecules (Basel, Switzerland)》2021,26(11)
This study investigated within-plant variability of the main bioactive compounds in rosemary (Rosmarinus officinalis L.). Volatile terpenes, including the enantiomeric distribution of monoterpenes, and phenols were analyzed in young and mature foliar, cortical and xylem tissues. In addition, antimicrobial activity of rosmarinic acid and selected terpenes was evaluated against two rosemary pathogens, Alternaria alternata and Pseudomonas viridiflava. Data showed that total concentration and relative contents of terpenes changed in relation to tissue source and age. Their highest total concentration was observed in the young leaves, followed by mature leaves, cortical and xylem tissues. Rosmarinic acid and carnosic acid contents did not show significant differences between leaf tissues of different ages, while young and mature samples showed variations in the content of four flavonoids. These results are useful for a more targeted harvesting of rosemary plants, in order to produce high-quality essential oils and phenolic extracts. Microbial tests showed that several terpenes and rosmarinic acid significantly inhibited the growth of typical rosemary pathogens. Overall, results on antimicrobial activity suggest the potential application of these natural compounds as biochemical markers in breeding programs aimed to select new chemotypes less susceptible to pathogen attacks, and as eco-friendly chemical alternatives to synthetic pesticides. 相似文献
66.
Dr. Antonino Scurria Dr. Marzia Sciortino Dr. Lorenzo Albanese Dr. Domenico Nuzzo Dr. Federica Zabini Dr. Francesco Meneguzzo Prof. Rosa Alduina Dr. Alessandro Presentato Dr. Mario Pagliaro Prof. Giuseppe Avellone Dr. Rosaria Ciriminna 《ChemistryOpen》2021,10(10):1055-1058
Following the analysis of terpenes present in new lemon and grapefruit “IntegroPectin” pectins obtained via the hydrodynamic cavitation of industrial lemon and grapefruit processing waste, the HPLC-MS analysis of flavonoid and other phenolic compounds reveals the presence of eriocitrin, naringin, hesperidin and kaempferol typical of the respective citrus fruits. The pectic fibers rich in rhamnogalacturonan-I regions act as chemical sponges adsorbing and concentrating at their outer surface highly bioactive citrus flavonoids and terpenes. These findings, together with the unique molecular structure of these new whole citrus pectins, provide preliminary insight into the broad-scope biological activity of these new biomaterials. Numerous new biomedical applications are anticipated, including likely use in the prevention and treatment of microbial infections and neurodegenerative disease. 相似文献
67.
A Stimuli‐Responsive Rotaxane–Gold Catalyst: Regulation of Activity and Diastereoselectivity
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Marzia Galli Dr. James E. M. Lewis Dr. Stephen M. Goldup 《Angewandte Chemie (International ed. in English)》2015,54(46):13545-13549
A rotaxane‐based Au catalyst was developed and the effect of the mechanical bond on its behavior was studied. Unlike the non‐interlocked thread, the rotaxane requires a catalytically innocent cofactor, the identity of which significantly influences both the yield and diastereoselectivity of the reaction. Under optimized conditions, AuI (the catalyst), AgI (to abstract the Cl? ligand), and CuI (the cofactor) combine to produce a catalyst with excellent activity and selectivity. 相似文献
68.
Graziano Baccolini Carla Boga Marzia Mazzacurati Magda Monari 《Heteroatom Chemistry》2005,16(5):339-345
Treatment, at room temperature, of benzothiadiphosphole 1 with BrMg(CH2)5MgBr gives intermediate A , which was allowed to stand for about 3 h at room temperature. The subsequent addition of RMgX to the reaction mixture and the final treatment with an excess of S8 and water affords the dithiaphosphepine sulfide 8 in good yields. The structure of this new heterocyclic system, containing both an S S unit and a PS group, is confirmed by an single crystal X‐ray structure determination. If the reaction is carried out without final treatment with sulfur we obtain, using PhMgBr as mono‐Grignard reagent, the corresponding ring‐opened product 11b , which can be easily transformed into the corresponding ring‐opened sulfide 12b by simple treatment with elemental sulfur. Further addition of sulfur to 12b gives quantitatively the cyclic dithiaphosphepine sulfide 8b . The two phosphanethiols 11b and 12b are of considerable interest. In fact, recently, attention has increasingly been paid to the coordination chemistry of polydentate ligands incorporating both thiolate and tertiary phosphine groups, also known as S P S pincer ligands. © 2005 Wiley Periodicals, Inc. Heteroatom Chem 16:339–345, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20099 相似文献
69.
Lucia Veltri Roberta Amuso Marzia Petrilli Corrado Cuocci Maria A. Chiacchio Paola Vitale Bartolo Gabriele 《Molecules (Basel, Switzerland)》2021,26(8)
A straightforward approach to new polycyclic heterocycles, 1H-benzo[4,5]imidazo[1,2-c][1,3]oxazin-1-ones, is presented. It is based on the ZnCl2-promoted deprotective 6-endo-dig heterocyclization of N-Boc-2-alkynylbenzimidazoles under mild conditions (CH2Cl2, 40 °C for 3 h). The zinc center plays a dual role, as it promotes Boc deprotection (with formation of the tert-butyl carbocation, which can be trapped by substrates bearing a nucleophilic group) and activates the triple bond toward intramolecular nucleophilic attack by the carbamate group. The structure of representative products has been confirmed by X-ray diffraction analysis. 相似文献
70.
Rosanna Toniolo Sabina Susmel Nicolò Dossi Andrea Pizzariello Marzia Martinis Gino Bontempelli 《Electroanalysis》2010,22(6):645-652
A porous gold electrode supported on one face of an ion‐exchange membrane, acting as a solid polymer electrolyte (SPE), is proposed as an amperometric sniffer for monitoring the aldehyde content in the headspace in equilibrium with lipid samples, in order to gain indication of their state of turning rancid It was used as a detector for a flow injection system in which aldehydes were injected, after preconcentration by solid phase microextraction on a SPME fiber from the gas phase standing above thermostated samples and subsequent desorption by heating. Repeatable (±4.5%) sharp peaks were detected over a wide linear concentration range (0.5–200 ppm). A detection limit of about 0.03 ppm was inferred for a signal‐to‐noise ratio of 3, referred to hexylaldehyde (used as prototype) dissolved in squalene or vegetable oils samples. This approach was applied to the determination of volatile aldehydes from some partially oxidized cereal oils and the results found were compared with both the corresponding peroxide values and their aldehyde content determined by a conventional spectrophotometric method. 相似文献