Sanghoo Lee

Investigation of inclusion complexation of paclitaxel by cyclohenicosakis-(1→2)-(β-d-glucopyranosyl), by cyclic-(1→2)-β-d-glucans (cyclosophoraoses), and by cyclomaltoheptaoses (β-cyclodextrins)

Abstract Inclusion complexation of the poorly soluble drug, paclitaxel, was investigated with various host cyclooligosaccharides such as a family of isolated neutral cyclohenicosakis-(1→2)-(β- d -glucopyranosyl) (cyclic-(1→2)-β- d -glucans, cyclosophoraoses), dimethyl cyclomaltoheptaose (cyclodextrins, DM-β-CD) and hydroxypropyl cyclomaltoheptaose (cyclodextrins, HP-β-CD). Quantitative analysis with high-performance liquid chromatography (HPLC) indicated that all three cyclic oligosaccharides could increase the solubility of paclitaxel, where DM-β-CD gave the best results and a family of cyclosophoraoses and HP-β-CD, both gave similar results. Complexation of host molecules with paclitaxel was studied by NMR and fluorescence spectroscopic analyses. NMR spectroscopic analysis showed that the aromatic regions of paclitaxel experienced noticeable changes of the chemical shifts or peak shapes upon interaction with host molecules. The relatively bulky cyclosophoraoses allowed favorable accessibility to either the B-ring or A-ring of paclitaxel, while DM-β-CD and HP-β-CD allowed accessibility to all the aromatic rings including the C ring. The interaction of DM-β-CD with paclitaxel greatly increased the fluorescence intensity compared with other host molecules, suggesting the more effective partitioning of a moderate fluorophore into a hydrophobic cluster adjacent to the C-ring of paclitaxel.

Enantioseparation using cyclosophoraoses as a novel chiral additive in capillary electrophoresis

Cyclosophoraoses, cyclic beta-(1-->2)-D-glucans produced by Rhizobium meliloti 2011, were used as a novel chiral additive for the separation of terbutaline, amethopterin, thyroxine and N-acetylphenylalanine enantiomers in aqueous capillary electrophoresis (CE). Enantioseparation took place in the normal- or reversed-polarity mode when a high concentration of neutral (60 mM) or anionic (40 mM) cyclosophoraoses was added to the background electrolyte (BGE).

Solubility enhancement of a hydrophobic flavonoid, luteolin by the complexation with cyclosophoraoses isolated from Rhizobium meliloti

A plant flavone, luteolin is a well-known inducer of nod genes in the Rhizobium meliloti. Its poor aqueous solubility was greatly enhanced by the complexation with a family of cyclosophoraoses synthesized in R .meliloti. Nuclear magnetic resonance (NMR) spectroscopic analysis showed that the chemical shifts of the aromatic ring moieties of the luteolin were changed greatly by the complexation with cyclosophoraoses. Fourier transform infrared (FTIR) spectroscopic analysis also showed a restricted vibrational pattern in carbonyl stretching region of the luteolin due to the complexation. This effective complex formation of cyclosophoraoses with a plant flavone, luteolin, suggests that rhizobial cyclosophoraoses play an important role as a solubility enhancer of the hydrophobic legume-derived flavonoids.

Comparison of serum and urinary nephrin levels between normal pregnancies and severe preeclampsia

OBJECTIVE To compare the levels of urinary excretion of nephrin in women experiencing either normotensive or severe preeclamptic pregnancies, and to examine the relationship between urinary nephrin levels and clinical parameters of preeclampsia. STUDY DESIGN In a case control study we collected serum and urine specimens from women with normal pregnancy (n=30) and from women with severe preeclampsia (n=43). Serum nephrin levels and urinary nephrin concentrations were measured in all patients. RESULTS Both serum and urine concentrations of nephrin were significantly higher in the severe preeclamptic group than in the normal pregnancy group. In addition, we identified a significant relationship between urinary nephrin levels and urine protein concentrations in the severe preeclamptic group. Urine nephrin concentrations were also correlated with serum creatinine levels and with diastolic blood pressure in the severe preeclamptic group. CONCLUSION The positive correlations observed in this study suggest that urinary nephrin excretion might play an important role in the pathogenesis of proteinuria during preeclampsia and could be a good indicator of renal damage.

13C NMR spectroscopic analysis on the chiral discrimination of N-acetylphenylalanine, catechin and propranolol induced by cyclic-(1→2)-β-d-glucans (cyclosophoraoses)

Cyclosophoraoses (cyclic-(1-->2)-beta-D-glucans) produced by Rhizobium meliloti were used as a novel chiral NMR solvating agent. 13C NMR spectroscopic analysis as an enantiodiscriminating tool was carried out where NMR signal splittings were observed on the interactions of cyclosophoraoses with the enantiomers of N-acetylphenylalanine, catechin and propranolol. The 13C chemical shifts of cyclosophoraoses induced by the enantiomeric interactions predominantly occurred at the C-1 and C-2 carbons associated with the -glycosidic linkage.

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometric behavior of succinoglycan monomers, dimers, and trimers isolated from Sinorhizobium meliloti 1021

Low-molecular-weight (LMW) succinoglycans (monomers, dimers, and trimers) were isolated from Sinorhizobium meliloti 1021 and have been firstly investigated by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) using 2,4,6-trihydroxyacetophenone (THAP) as an optimal matrix in the negative ion mode. The main fractions of LMW succinoglycans contain molecules assembled of octasaccharide subunits. MALDI-TOF mass spectra of the LMW succinoglycan monomers, the dimers, and the trimers showed the daughter ions resulting from the losses of the terminal galactose residues at the reducing ends, clearly indicating that the galactosyl linkages are more labile than the other glucosyl linkages. Furthermore, the losses of the acetyl groups as substituents rather than the succinyl and pyruvyl ester linkages by prompt fragmentation primarily occurred during MALDI-TOF analysis, suggesting the greater instability of acetyl linkages compared to pyruvyl and succinyl linkages.

AGAROSE AND GELLAN AS MORPHOLOGY-DIRECTING AGENTS FOR THE PREPARATION OF SELENIUM NANOWIRES IN WATER

Commercially available polysaccharides, agarose and gellan, were used as morphology-directing agents for the synthesis of t-Se nanowires in water at room temperature in the presence of ascorbic acid as reducing agent. The nanostructures were characterized using XRD, SEM, and TEM. The diameter of the nanowires varied from 100 to 208 nm for nanowires obtained in the presence of agarose and from 51 to 145 nm for nanowires from gellan, as evidenced by SEM and TEM. Agarose and gellan have then a potential as environmentally acceptable morphology-directing agents to generate Se nanostructures in water.

Simultaneous determination of cortisol and cortisone from human serum by liquid chromatography-tandem mass spectrometry.

A fast, sensitive, and selective liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was validated and then the levels of cortisol and cortisone from sera of healthy adults were determined by the LC-MS/MS method. One hundred μL of serum sample was directly extracted by adding 2 mL ethyl acetate, followed by chromatographic separation on a C18 column with a mobile phase consisting of 5 mM ammonium acetate and methanol (25 : 75, v/v). The precision, accuracy, and average recovery of the method were 1.5–5.3%, 95.4–102.5%, and 96.4% for cortisol, and 1.9–6.0%, 89.2–98.8%, and 79.9% for cortisone, respectively. The method was linear from 1.0 to 500.0 ng/mL (r2 = 0.999) for cortisol and 2.5 to 100.0 ng/mL (r2 = 0.998) for cortisone. The limits of detection (LOD) and quantification (LOQ) were 0.2 and 1.0 ng/mL for cortisol, and 1.0 and 2.5 ng/mL for cortisone, respectively. The average cortisol concentration (133.9 ± 63.7 ng/mL) of samples collected between 9:00 and 11:00 a.m. was higher approximately 4.4 times than that of cortisone (30.5 ± 10.7 ng/mL) (P < 0.0001). The average cortisone/cortisol ratio was 0.225. Therefore, the LC-MS/MS method may be useful for the diagnosis of some adrenal diseases and the assessment of 11β-hydroxysteroid dehydrogenase (11β-HSD) activity in clinical laboratories.

Synthesis of selenium nanowires morphologically directed by Shinorhizobial oligosaccharides

Shinorhizobial cyclosophoraose (cyclic beta-(1-->2)-glucan) or succinoglycan monomer (SGM 2), which has one acetyl, pyruvyl, and succinyl group, functions as a morphology-directing agent for the synthesis of pure trigonal selenium nanowires by using ascorbic acid (vitamin C) as the reducing agent. The synthesis was achieved in water at room temperature. Under these experimental conditions, the diameters of the as-prepared Se nanowires were varied in the range of 34-120 nm by cyclosophoraose and of 33-66 nm by SGM 2, in which the nanowires were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Raman spectroscopy. Through this study, we propose that Shinorhizobial cyclic and linear oligosaccharides have morphologically directing functions for the synthesis of single-crystalline selenium nanowires by green chemical methods.

Low-energy collision-activated dissociation electrospray ionization tandem mass spectrometric analysis of Sinorhizobial succinoglycan monomers.

Succinoglycan monomers (M1, M2, and M3) are octasaccharides with acetyl, pyruvyl, and/or succinyl groups as substituents derived from Sinorhizobium meliloti 1021. The dissociation patterns of the octasaccharides caused by low-energy collision-activated dissociation (CAD) were investigated using triple quadrupole tandem mass spectrometry (MS) equipped with an electrospray ionization (ESI) source with increasing collision energy (CE) in negative ion mode. None of the succinoglycan monomers were fragmented at a CE of -25eV. When the CE was applied to -50 or -70eV, the loss of the terminal Gal residue and/or the succinyl group of the monomers was observed in the product ion scan mode. Interestingly, the acetyl and the pyruvyl groups in the succinoglycan monomers were not lost even when a CE of -70eV was applied, indicating that the substituents are more stable than the succinyl group in the octasaccharides.