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651.
Enantioseparation of chiral sulfonates by liquid chromatography and subcritical fluid chromatography
Tert‐butylcarbamoyl‐quinine and ‐quinidine weak anion‐exchange chiral stationary phases (Chiralpak® QN‐AX and QD‐AX) have been applied for the separation of sodium β‐ketosulfonates, such as sodium chalconesulfonates and derivatives thereof. The influence of type and amount of co‐ and counterions on retention and enantioresolution was investigated using polar organic mobile phases. Both columns exhibited remarkable enantiodiscrimination properties for the investigated test solutes, in which the quinidine‐based column showed better enantioselectivity and slightly stronger retention for all analytes compared to the quinine‐derived chiral stationary phase. With an optimized mobile phase (MeOH, 50 mM HOAc, 25 mM NH3), 12 of 13 chiral sulfonates could be baseline separated within 8 min using the quinidine‐derivatized column. Furthermore, subcritical fluid chromatography (SubFC) mode with a CO2‐based mobile phase using a buffered methanolic modifier was compared to HPLC. Generally, SubFC exhibited slightly inferior enantioselectivities and lower elution power but also provided unique baseline resolution for one compound. 相似文献
652.
Determination of Catechins and Purine Alkaloids in Tea by High Performance Liquid Chromatography 总被引:2,自引:0,他引:2
《Analytical letters》2012,45(17):2530-2537
With a novel internal standard, 8-chlorotheophylline, a high-performance liquid chromatography method was successfully developed for simultaneous determination of six catechins, three purine alkaloids, and gallic acid in green tea, oolong tea, and black tea. The analysis was carried out on a C18 column with the temperature of 35°C, and a gradient elution was adopted with a mobile phase composed by aqueous solution (containing 0.2% acetic acid, v/v) and acetonitrile. The optimal detection wavelength was 278 nm, of which both of the analytes and internal standard displayed the highest UV adsorption. Both the internal standard (ISTD) method and external standard (ESTD) method had wide linear range, good precision (coefficients of variation CV ≤ 3.65%), good intermediate precision (CV ≤ 5.82%), and good accuracy (recovery 92%–120%). Compared with the ESTD method, the ISTD method had better precision and lower test costs. 相似文献
653.
Yusuke HirasawaRyo Matsuya Khozirah ShaariNordin Hj Lajis Nahoko UchiyamaYukihiro Goda Hiroshi Morita 《Tetrahedron letters》2012,53(31):3971-3973
Novel C16N2-type Lycopodium alkaloids consisting of a decahydroquinoline with an aminohexyl side chain, lycobelines A-C (1-3), were isolated from the club moss of Huperzia goebelii, and their structures and relative stereochemistry were elucidated on the basis of spectroscopic data and chemical correlations. 相似文献
654.
A new 1,3-alternate 25,27-dibenzoiloxy-26,28-bis-[3-propyloxy]-calix[4]arene-bonded silica gel stationary phase (1,3-Alt CalixBn) has been prepared and used for the separation of aromatic positional isomers by high-performance liquid chromatography (HPLC). The effect of organic modifier content and pH of the mobile phase on retention and selectivity of these compounds were studied. Application examples were provided for separation of purine and pyrimidine bases and non-steroidal anti-inflammatory drugs. 相似文献
655.
656.
657.
A new purine nucleoside coupled with an amino acid derivative,N~2-(1-methoxycarbonylethyl)guanosine 1,along withβ-carboline and russulaceramide was isolated from the fruiting bodies of Amanita exitialis,a newly described poisonous mushroom. Its structure was elucidated by spectroscopic methods.This is the first report of naturally occurring nucleosides in which anα-amino acid derivative is bonded through itsα-amino nitrogen to a nucleobase aglycone by a C-N bond.The new compound was found to be toxic in ... 相似文献
658.
659.
Van Durme Kurt Van Assche Guy Rahier Hubert Van Mele Bruno 《Journal of Thermal Analysis and Calorimetry》2009,95(2):495-499
The inhibitory effects of three berberine alkaloids (BAs) from Coptis chinensis Franch on Bifidobacterium adolescentis growth were investigated by microcalorimetry. The growth rate constant (k) and maximum heat-output power (Pmax) decreased and peak time of maximum heat-output power (tp) prolonged with the increase of BAs concentration. Half inhibitory ratios (IC50) BAs were respectively 790.3 (berberine),
339.6 (coptisine) and 229.8 μL−1 (palmatine), which indicated the sequence of their antimicrobial activity: berberine<coptisine<palmatine. Combined with previous
findings, the sequence which could show the bioactivity of Bacillus shigae and Escherichia coli was: berberine>coptisine>palmatine. The structure-function relationship of BAs indicated that the functional group methylenedioxy
or methoxyl at C2 and C3 might be the major group inducing the activities of BAs on E. coli and B. adolescentis. Meanwhile, the substituent groups at C2, C3, C9 and C10 almost had equal effect on B. shigae. 相似文献
660.
Lorene Coelho Silva Amabel Fernandes Correia Joo Victor Dutra Gomes Wanderson Romo Larissa Campos Motta Christopher William Fagg Prola Oliveira Magalhes Dmaris Silveira Yris Maria Fonseca-Bazzo 《Molecules (Basel, Switzerland)》2022,27(9)
Candida species are the main fungal agents causing infectious conditions in hospital patients. The development of new drugs with antifungal potential, increased efficacy, and reduced toxicity is essential to face the challenge of fungal resistance to standard treatments. The aim of this study is to evaluate the in vitro antifungal effects of two crude extracts of Crinum americanum L., a rich alkaloid fraction and lycorine alkaloid, on the Candida species. As such, we used a disk diffusion susceptibility test, determined the minimum inhibitory concentration (MIC), and characterized the components of the extracts using Electrospray Ionization Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (ESI FT-ICR MS). The extracts were found to have antifungal activity against various Candida species. The chemical characterization of the extracts indicated the presence of alkaloids such as lycorine and crinine. The Amaryllidaceae family has a promising antifungal potential. Furthermore, it was found that the alkaloid lycorine directly contributes to the effects that were observed for the extracts and fraction of C. americanum. 相似文献