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mM L (mm + l)
Selected AbstractsChiral CE of aromatic amino acids by ligand-exchange with zinc(II),L -lysine complexELECTROPHORESIS, Issue 15 2007Li Qi Abstract A novel method of chiral ligand-exchange CE was developed with either L - or D -lysine (Lys) as a chiral ligand and zinc(II) as a central ion. This type of chiral complexes was explored for the first time to efficiently separate either individual pairs of or mixed aromatic amino acid enantiomers. Using a running buffer of 5,mM ammonium acetate, 100,mM boric acid, 3,mM ZnSO4·7H2O and 6,mM L -Lys at pH,7.6, unlabeled D,L -tryptophan, D,L -phenylalanine, and D,L -tyrosine were well separated, giving a chiral resolution of up to 7.09. The best separation was obtained at a Lys-to-zinc ratio of 2:1, zinc concentration of 2,4,mM and running buffer pH,7.6. The buffer pH was determined to have a strong influence on resolution, while buffer composition and concentration impacted on both the resolution and peak shape. Boric acid with some ammonium acetate was an adoptable buffer system, and some additives like ethylene diamine tetraacetic acid capable of destroying the complex should be avoided. Fine-tuning of the chiral resolution and elution order was achieved by regulating the ratio of L -Lys to D -Lys; i.e. the resolution increased from zero to its highest value as the ratio ascended from 1:0 to 1:infinitive, and L -isomers eluted before or after D -isomers in excessive D - or L -Lys, respectively. [source] Amino acids protect epithelial cells from local toxicity by absorption enhancer, sodium laurateJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 10 2001Takashi Yata Abstract To develop the safe absorption-enhancing formulation attenuating the local toxicity caused by an absorption enhancer, sodium laurate (C12), the effects of amino acids on the local toxicity by C12 were examined in rats. The absorption of phenol red, an unabsorbable marker drug, was significantly enhanced by 10 mM C12 in an in situ colon loop study and the addition of L -glutamine (L -Gln), L -arginine, or L -methionine at 10 mM did not change the promoting effect of C12. However, C12 significantly increased the elution of phospholipids, total protein, and lactate dehydrogenase, which are markers for local toxicity, from colon, but these amino acids attenuated the local toxicity caused by C12 significantly. Transport study using an Ussing-type chamber showed that the permeability of colonic membrane to phenol red was significantly enhanced by C12 and that L -Gln did not decrease the permeability enhanced by C12. Transmucosal electrical resistance was extensively decreased by C12, indicating that C12 could enhance the drug absorption at least partly by expanding the paracellular route. L -Gln significantly, but not completely, recovered resistance lowered by C12. Electrical potential difference was markedly reduced by C12, suggesting that C12 lowered the viability of mucosal cells, but 10 mM L -Gln significantly recovered potential difference almost to the control level. These results suggested the possibility that absorption-enhancing formulation with low local toxicity, which is low enough to be used practically, could be developed by using an amino acid like L -Gln as an ingredient attenuating the local toxicity caused by C12. © 2001 Wiley-Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 90:1456,1465, 2001 [source] Enantioseparation of dansyl amino acids by ligand-exchange capillary electrophoresis with zinc(II)- L -phenylalaninamide complexJOURNAL OF SEPARATION SCIENCE, JSS, Issue 18 2009Li Qi Abstract A novel method of chiral ligand-exchange CE was developed with L -amino acylamides as a chiral ligand and zinc(II) as a central ion. It has been demonstrated that these chiral complexes, such as Zn(II)- L -alaninamide, Zn(II)- L -prolinamide, and Zn(II)- L -phenylalaninamide, are suitable for use as chiral selectors for the enantioseparation of either individual pair of or mixed dansyl amino acids. The optimal separation running buffer consisted of 5 mM ammonium acetate, 100 mM boric acid, 4 mM ZnSO4·7 H2O, and 8 mM L -amino acylamides at pH 8.2. The experiments showed that apart from the effect of the concentration of the complexes on the resolution and the migration time, the buffer pH also had a sharp influence on resolution. The employed chiral ligands exhibited different enantioselectivities and enantiomer migration orders. D -Amino acids migrate faster than L -amino acids when Zn(II)- L -alaninamide and Zn(II)- L -phenylalaninamide are used as chiral selectors, but it was observed that the migration order is reversed when Zn(II)- L -prolinamide is used as the chiral selector. Furthermore, the amount of dansylated amino acids is found to be highly dependent on the labeling temperature. [source] Sperm motility and seminal plasma characteristics in Barbus sharpeyi (Günther, 1874)AQUACULTURE RESEARCH, Issue 10 2010Sayyed Mohammad Hadi Alavi Abstract Spermatozoa concentration, ionic composition, osmolality, glucose and total protein contents of seminal plasma and sperm motility were determined in Barbus sharpeyi (Cyprinidae, Teleosotei). Spermatozoa concentration ranged from 9.77 to 20.20 × 109 spermatozoa mL,1. Osmolality (mOsmol kg,1) and ionic contents (mM L,1) of the seminal plasma were 274.5±9.0, 70.0±3.4 Na+, 28.8±0.9 K+, 101.7±3.1 Cl,, 0.9±0.1 Mg2+ and 2.1±0.1 Ca2+ respectively. Total protein and glucose were 5.3±0.2 g L,1 and 76.7±4.3 mM L,1 respectively. Sperm motility was initiated in a hypo-osmotic condition, composed of either an ionic (KCl or NaCl) or a non-ionic (sucrose) activation medium. Duration of sperm motility was very short: <2 min after activation in distilled water. Percentage of motile spermatozoa was significantly higher in an activation medium containing NaCl compared with that of distilled water. An activating medium containing NaCl or KCl higher than 150 mM or sucrose higher than 275 mM totally inhibited the activation of sperm motility. Immediately after sperm activation, wave(s) propagated along the flagellum, but waves were restricted to the proximal part of the flagellum (close to the head) at 1 min post activation. Studied characteristics in the present study were compared with those of other cyprinids for understanding inter-species differences. [source] Sperm motility and fertilizing ability in the Persian sturgeon Acipenser persicusAQUACULTURE RESEARCH, Issue 9 2005Sayyed Mohammad Hadi Alavi Abstract The motility and fertilizing ability of the Persian sturgeon, Acipenser persicus, spermatozoa were investigated. Optimum ionic content (Na+, K+, Ca2+ and Mg2+) and pH of activation solution as well as the optimum dilution rate were determined. The results show optimum motility characteristics of spermatozoa in buffered solutions containing 25, 0.2, 3 and 10 mM L,1 Na+, K+, Ca2+ and Mg2+, respectively, at dilution rate 1:50 and pH 8.0. To test the fertilizing ability of sperm, two buffered saline solutions were used as activation solution of sperm motility. The present study indicated (1) spermatozoa motility is one of key factors that influence on fertilizing ability of sperm, (2) a high fertilizing ability of sperm is obtained after dilution in saline solutions rather than in freshwater and (3) a maximum fertilization rate occurs in buffered saline solution containing 0.2 mM L,1 K+. There is also a good correlation between biochemical characteristics of seminal plasma and fertilizing ability of sperm. [source] | ||||||||||