- An easily prepared hypersensitive water-soluble fluorescent probe for mercury(ii) ions
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A hypersensitive water-soluble fluorescent probe, dansyl-l-tryptophan methyl ester (1), was easily prepared for the detection of Hg2+ with a significantly improved detection limit (5 nM vs. 500 nM) in buffered aqueous solution. The Royal Societ
- Li, Hong-Wei,Li, Yue,Dang, Yong-Qiang,Ma, Li-Jun,Wu, Yuqing,Hou, Guangfeng,Wu, Lixin
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- A new chiral ligand exchange capillary electrophoresis system based on Zn(ii)-l-leucine complexes coordinating with β-cyclodextrin and its application in screening tyrosinase inhibitors
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Tyrosinase plays a key role in melanin formation, and it is closely related to hyper pigmentation in animals and enzymatic browning in food. Thus, it is of great significance to screen inhibitors of tyrosinase. In this work, a new chiral ligand exchange-capillary electrophoresis (CLE-CE) system based on the coordination effect of Zn(ii)-l-leucine complexes and β-cyclodextrin (β-CD) was developed for screening the inhibitors of tyrosinase. The effects of the concentration of β-CD, buffer pH, the ratio of l-leucine to Zn(ii), and the complex concentration were investigated with Dns-d,l-tyrosine, Dns-d,l-valine and Dns-d,l-phenylalanine as the tested analytes. The optimum buffer conditions were composed of 100.0 mM boric acid, 5.0 mM ammonium acetate, 3.0 mM Zn(ii), 6.0 mM l-leucine and 4.0 mM β-CD at pH 8.2. It has been found that six pairs of Dns-d,l-AAs could be baseline-separated and five pairs of Dns-d,l-AAs were partly enantioseparated. Then the quantitative analysis of l-tyrosine was conducted and good linearity (r2 = 0.992) was obtained with a concentration ranging from 12.95 μM to 413.3 μM. A kinetics study of tyrosinase was realized, and the Km and Vmax were 636 μM and 312 μmol min-1 mg-1. Moreover, the proposed method was applied in screening the inhibitors of tyrosinase with four kinds of chalcones as the model inhibitors. The results demonstrated that the developed CLE-CE system was favorable for screening enzyme inhibitors, and showed great potential in related drugs discovery and clinical analysis in the future.
- Su, Yuan,Mu, Xiaoyu,Qi, Li
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p. 55280 - 55285
(2015/02/05)
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- Chiral separation of enantiomers of amino acid derivatives by HPLC on vancomycin and teicoplanin chiral stationary phases
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The chiral separation of α-amino acids by liquid chromatography using macrocyclic antibiotic bonded stationary phases were studied. Teicoplanin and vancomycin bonded stationary phases have been used to separate enantiomers of dansyl amino acids in the reversed - phase high performance liquid chromatography mode. By comparison of chromatographic parameters obtained by use of both chiral stationary phases it the mechanism of chiral separation could be suggested. The better separation - greater value of R(j,i) of enantiomers - was achieved by the teicoplanin column.
- Lehotay, Jozef,Hrobonova,Krupcik,Cizmarik
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p. 863 - 865
(2007/10/03)
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- Direct resolution of optically active isomers on chiral packings containing ergoline skeletons. 5. Enantioseparation of amino acid derivatives
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A new procedure for ergot alkaloid-based chiral stationary phase preparation is described. Synthesis is based on bonding the allyl derivative of terguride to mercaptopropylsilanized silica gel. The packing exhibits higher content of chiral selector, stability, reproducibility, and enantioselectivity toward amino acids compared to that previously studied. The chromatographic behavior of amino acids with different side chains and substituent groups is investigated in order to obtain a deeper insight into the enantiodiscriminative mechanism as well as to determine the limitations and strengths of terguride as a chiral selector for this class of compounds. A variety of factors, including mobile phase parameters such as pH, ionic strength, content and nature of organic modifier, and temperature, are examined. A new procedure for ergot alkaloid-based chiral stationary phase preparation is described. Synthesis is based on bonding the allyl derivative of terguride to mercaptopropylsilanized silica gel. The packing exhibits higher content of chiral selector, stability, reproducibility, and enantioselectivity toward amino acids compared to that previously studied. The chromatographic behavior of amino acids with different side chains and substituent groups is investigated in order to obtain a deeper insight into the enantiodiscriminative mechanism as well as to determine the limitations and strengths of terguride as a chiral selector for this class of compounds. A variety of factors, including mobile phase parameters such as pH, ionic strength, content and nature of organic modifier, and temperature, are examined.
- Messina,Girelli,Flieger,Sinibaldi,Sedmera,Cvak
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p. 1191 - 1196
(2007/10/03)
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