1H and 31P NMR studies of rotational isomerism in phosphorus analogues of aspartic acid, 3-amino-3-phosphonatopropionic and 3-amino-3-(methylphosphinato) propionic acids

By the use of the ¹H? ¹H and ¹H? ³¹P coupling constants in two analogues of aspartic acid i.e. 3-amino-3-phosphonatopropionic and 3-amino-3-(methylphosphinato) propionic acids, it was shown that the six parameter formulation for the evaluation of mole fractions of three staggered ethanic rotamers is not necessarily better than the two parameter formulation in this system. The results allowed the recommendation of the following values for the two vicinal proton parameters i.e. J(HH)g=2.3, J(HH)t=13.9 and for the two vicinal proton-phosphorus parameters i.e. J(HP)g=4.2, J(HP)t=33.0 Hz.     

The compound Tl4Cu4(P2O7)3, a new three-dimensional structure with interconnected tunnels

Tl₄Cu₄(P₂O₇)₃ has the following crystallographic features: orthorhombic space group Pcca with a=20.171(2), b=10.558(1), c=9.676(1) Å and Z=4. A total of 1303 reflections with I>2(I) were used for structure solution and refinements. The agreement factors R₁ and WR² converged to 0.040 and 0.093, respectively. GOF=1.103. Tl₄Cu₄(P₂O₇)₃ presents a three-dimensional structure, its anionic framework consists of corner sharing CuO₅ polyhedra and P₂O₇ groups delimiting several types of interconnected tunnels wherein the thallium cations reside.     

Isolation, structure and fatty acid synthesis inhibitory activities of platensimycin B1-B3 from Streptomyces platensis

Platensimycins B(1)-B(3) are natural congeners of platensimycin with modest to significant changes in the benzoic acid portion of the molecule, leading to attenuation in the biological activities and thus confirming the significance of the free carboxylate for the potent activity.     

Syntheses of prodelphinidin B1, B2, and B4 and their antitumor activities against human PC-3 prostate cancer cell lines

Total synthesis of prodelphinidin B1, B2, and B4 has been accomplished. The key step is Lewis acid-mediated equimolar condensations between an epigallocatechin and/or a gallocatechin nucleophile and an epigallocatechin and/or a gallocatechin electrophile. The antitumor effects of synthetic prodelphinidin B1–B4 against human PC-3 prostate cancer cell lines have been investigated. These compounds showed significant antitumor effects. Their activity seemed to be little bit stronger than EGCG and prodelphinidin B3, known antitumor agent.     

外型-1,4-氧桥-环己基-2,3-二羧酸的晶体及分子结构

外型-1,4-氧桥-环己基-2,3-二羧酸晶体属单斜晶系,空间群为P2_1/n;晶胞参数为:α=5.594(3)A,b=11.178(7)A,c=14.675(11)A,β=91.46(5)°;Ζ=4.从直接法得到结构的初始模型,经块矩阵最小二乘修正后,最后的R值为0.072.在晶体中,分子间的O—H…O氢键将分子连接成层型氢键体系.使用自编的CNDO/2程序,计算得电子的能量、分子的总能量、偶极矩及各原子的电荷密度和净电荷.     

Synthesis, crystal structure, and DNA interaction and cleavage studies of a novel dinuclear Cu(II) complex with 3-indolylacetic acid

A novel dinuclear Cu(II) complex [Cu₂(C₁₀H₈NO₂)₄(CH₃OH)₂] · 2CH₃OH (I), where C₁₀H₈NO₂ is anion of 3-indolylacetic acid, was synthesized and characterized by elemental analysis, IR spectroscopy, ¹H NMR and single crystal X-ray diffraction. X-ray crystallography shows that Cu²⁺ ion is six-coordinated, embedded in a distorted octahedral center. Each Cu²⁺ ion is coordinated with four carboxylic oxygen atoms from four ligands, one oxygen atom from methanol and the other Cu²⁺ ion. Each ligand links two Cu²⁺ ions through carboxylic oxygen atoms, forming a dinuclear Cu(II) complex. The complex forms a two-dimensional layer structure through N-H??Oⁱ intermolecular hydrogen bonds. The interaction of complex I with calf-thymus DNA (CT-DNA) has been explored by electronic absorption spectroscopy, EB (ethidium bromide) displacement experiments, salt effect, and viscosity measurements. All the results indicate that the complex binds to DNA in a partial intercalative mode. Moreover, agarose gel electrophoresis assay demonstrates that the complex possesses the ability to cleave pBR322 plasmid DNA.     

Tanshinone IIA, an ingredient of Salvia miltiorrhiza BUNGE, induces apoptosis in human leukemia cell lines through the activation of caspase-3

Tanshinone II-A is a derivative of phenanthrene-quinone isolated from Salvia miltiorrhiza BUNGE, a traditional herbal medicine that is known to induce antiinflammatory, anti-oxidative and cytotoxic activity. We have examined cellular effects of Tanshione II-A on HL60 human promyelocytic leukemic cells and K562 human erythroleukemic cells. Tanshione II-A induced a dose- and time-dependent DNA fragmentation into the multiples of 180 bp and specific proteolytic cleavage of poly(ADP-ribose) polymerase in both cell lines. PI-staining and flow cytometry analysis of K562 cells following Tanshione II-A treatment showed an increase of the cells possessing hypodiploid DNA indicative of apoptotic state of cells. Caspase-3 activity was significantly increased during Tanshinone II-A treatment of both HL60 and K562 cells, whereas caspase-1 activity was not changed. These results suggest that Tanshione II-A induced HL60 and K562 cellular apoptosis that may be associated with the selective members of caspase family.     

Annexin II, a novel HSP27-interacted protein, is involved in resistance to UVC-induced cell death in human APr-1 cells

Heat shock protein 27 (HSP27) is implicated in diverse biologic functions as a molecular chaperone. We found that HSP27 is involved in the protection of human cells against UVC lethality. To elucidate the molecular mechanisms underlying UVC resistance, we searched for HSP27-interacted proteins related to resistance in UVC-resistant human cells, APr-1. Three candidates for HSP27-interacted proteins were found from cell lysates using an affinity column coupled with GST-fused HSP27 protein. Interaction between HSP27 and two candidates, annexin II and HSP70, was confirmed by immunoprecipitation analysis. After UVC irradiation, the amount of the complex of HSP27 and annexin II decreased in the postnuclear fraction, while it increased in the nuclear fraction. Cells transfected with annexin II-siRNA were more susceptible to UVC lethality. These results suggest that annexin II is a novel HSP27-interacted protein which is involved in UVC resistance in human cells, at least those tested here.     

Molecular structure and vibrational investigation of benzenesulfonic acid methyl ester using DFT (LSDA, B3LYP, B3PW91 and MPW1PW91) theory calculations

The FT-Raman and FT-IR spectra for benzenesulfonic acid methyl ester (BSAME) have been recorded in the region 4000-100 cm(-1) and compared with the harmonic vibrational frequencies calculated using DFT (LSDA, B3LYP, B3PW91 and MPW1PW91) method by employing 6-311G (d, p) basis set with appropriate scale factors. IR intensities and Raman activities are also calculated by DFT (LSDA, B3LYP, B3PW91 and MPW1PW91) methods. Optimized geometries of the molecule have been interpreted and compared with the reported experimental values for sulfonic acid and some substituted sulfonic acids. The experimental geometrical parameters show satisfactory agreement with the theoretical prediction from DFT. The scaled vibrational frequencies at LSDA/B3LYP/6-311G (d, p) seem to coincide with the experimentally observed values with acceptable deviations. The theoretical spectrograms (IR and Raman) have been constructed and compared with the experimental FT-IR and FT-Raman spectra. Some of the vibrational frequencies of the sulfonic acid are effected upon profusely with the methyl substitution in comparison to benzene sulfonamide and these differences are interpreted.     

A modified HPLC method for the determination of aspartic acid racemization in collagen from human dentin and its comparison with GC

The D/L ratio of aspartic acid enantiomers in proteins of low turnover is generally accepted as a reliable procedure for age determination. In our study, twelve samples of eyetooth dentin were analyzed for age determination. The pure insoluble collagen isolated from eyetooth dentin was obtained by an EDTA demineralization process. Free amino acids obtained after collagen hydrolysis were converted into o-phthaldialdehyde-N-acetyl-L-cysteine (OPA-NAC) derivatives for HPLC analysis under modified conditions and into trifluoroacetic acid isopropyl esters for GC analysis, respectively. The modified HPLC procedure used phosphate buffer and acidified sample matrix prior to injection which resulted in suppression of peak tailing of both diastereomers, thus allowing achievement of both good selectivity and good resolution. To ensure the high accuracy of the developed method the other parameters, i.e. specificity, precision, linearity, LOD, and LOQ, were also determined. Nine collagen samples covering the age range of 18 to 84 years were used for the determination of coefficient of racemization (KR) and calculation of parameters for age estimation. The regression equations for the data set analyzed were as follows: KR= 0.0005 x age + 0.0262 (R2 = 0.9639) for HPLC, and KR= 0.0006 x age + 0.0319 (R2 = 0.9374) for GC, respectively.     

Application of molecularly imprinted polymers to determine B1, B2, and B3 fumonisins in cereal products

The aim of this study was to develop an analytical method for qualitative and quantitative determination of the B₁, B_2, and B₃ fumonisins in cereal products. A LC coupled to an IT‐MS was used as the analytical instrument. The AFFINIMIP FumoZON Molecularly Imprinted Polymer SPE cartridges (Polyintell) were used to isolate fumonisins from the analyzed samples and the clean‐up step. Statistical parameters evaluated in some validation experiments were as follows: mean recovery 95–106%, precision <17% (expressed as recovery RSD). The developed method was used to determine fumonisins in 49 cereals (42 maize‐based and seven wheat‐based products). In most cases, concentrations of the studied compounds found in the analyzed samples were low. The highest total concentration of the B₁, B₂, and B₃ fumonisins was found in maize flour samples (range, 26–1102 μg/kg, mean 498 μg/kg).     

Synsthesis,crystal structure,photoluminescence, DNA cleavage,and cytotoxicity in vitro of the binuclear Ce(III) complex with quinaldic acid

A novel binuclear complex [Ce₂(Qina)₆(H₂O)₃] · 3H₂O has been synthesized by the reaction of Ce(NO₃)₃ and quinaldine acid (Qina) under hydrothermal conditions. The central ion shows 9-coordination with four Qina and three H₂O molecules, in which Qina adopts three coordination modes. The 2D and 3D framework is constructed via intermolecular hydrogen bonds and π-π stacking interactions. The complex displays an obvious photoluminescent emission upon excitation at 300 nm in solid. Gel electrophoresis assay demonstrates the ability of the complexes to cleave the pBR322 plasmid DNA. The cytotoxic activity of the complex was tested against two different cancer cell lines. The result exhibited cytotoxic specificity and significant cancer cell inhibitory rate. The article is published in the original.     

Kinetic evidence for high reactivity of 3-nitrophenylboronic acid compared to its conjugate boronate ion in reactions with ethylene and propylene glycols

The rate constants for a boronate ion were determined for the first time using the reaction systems of 3-nitrophenylboronic acid (3-NO2PhB(OH)2) with ethylene glycol (EG) and propylene glycol (PG) in an alkaline solution: the rate constants (25 degrees C, I = 0.10 M) for the reactions of 3-NO2PhB(OH)3- are 1.2 M(-1) s(-1) (EG) and 1.5 M(-1) s(-1) (PG), which are at least 10(3) times smaller than those for the reactions of 3-NO 2PhB(OH)2 [1.0 x 10(4) M(-1) s(-1) (EG) and 5.8 x 10(3) M(-1) s(-1) (PG)].     

Solvent extraction clean-up for pre-treatment in amino acid analysis by gas chromatography. Application to age estimation from the D/L ratio of aspartic acid in human dentine

Solvent extraction, a clean-up method for samples for the determination of amino acids by gas chromatography, was investigated and compared with a conventional ion-exchange purification. Amino acids were esterified with isopropanol and extracted with various organic solvents. The solubilities of the amino acid isopropyl esters increased with increasing solvent polarity and the size of the amino acids. The optimum pH was found to be 10.5. The method was applied to the estimation of ages by measurement of the D/L ratio of aspartic acid in human dentine. The D/L ratios so determined were slightly lower than from the ion-exchange method with respect to all dentines examined. However, there were little or no significant differences in the ages estimated by both methods, and the correlation coefficient of this method was 0.982. The method is suitable for the enantiomeric analysis of amino acids, and has several advantages in the technique and time.     

Development of a multiplex UPLC-MRM MS method for quantification of human membrane transport proteins OATP1B1, OATP1B3 and OATP2B1 in in vitro systems and tissues

OATP1B1, OATP1B3 and OATP2B1 are important members of the organic anion transporting polypeptides (OATP) family and are implicated in the hepatic disposition of endobiotics and xenobiotics. Quantitating the expression levels of human OATP1B1, OATP1B3 and OATP2B1 in in vitro systems and tissue samples could significantly improve attempts to scale up in vitro data and result in more effective in vitro–in vivo correlation of transporter-mediated effects on drug disposition, such as hepatic clearance. In the present study, a quantification method was developed, characterized, and implemented for simultaneous determination of human OATP1B1, OATP1B3 and OATP2B1 in HEK cells transfected with OATP-expressing plasmid vectors (SLCO1B1, SLCO1B3, and SLCO2B1, respectively), human hepatocytes, human brain capillary endothelial cells, and humanized mouse liver tissue using UPLC-MRM MS. Purified membrane protein standards prepared and characterized as previously reported (Protein Expr. Purif. 2008, 57, 163-71) were first used as standards for absolute quantification of the expression levels of the three human OATP membrane proteins. The specificity of the optimized MRM transitions were characterized by analyzing the tryptic digests of the membrane protein fraction of wild type HEK cells and control mouse liver tissue using the herein reported UPLC-MRM MS method. The linearity of the calibration curve spanned from 0.2 μg mL⁻¹ (0.040 μg mg⁻¹) to 20 μg mL⁻¹ (4.0 μg mg⁻¹), with accuracy (% RE) within 15% at all concentrations examined for all three OATPs of interest in this study. The intra- and inter-day assay accuracy (% RE) and coefficient of variations (% CV) of triplicates are all within 15% for all levels of quality control samples prepared by mixing the membrane fraction of control mouse liver tissue with the required amount of purified human OATP1B1, OATP1B3 and OATP2B1.     

Synthesis,structure, and DNA cleavage activity of new trinuclear Zn(3) and Zn(2)Cu complexes of a chiral macrocycle: structural correlation with the active center of P1 nuclease

New homo trinuclear Zn(II) complexes [Zn(3)L(1)(micro-OAc)](ClO(4))(2).3CHCl(3).H(2)O, 1, and [Zn(3)L(1)(micro-OAc)].ClO(4).PF(6).5CH(3)OH.H(2)O, 2, and hetero trinuclear complex [Zn(2)CuL(1)(micro-OAc)](ClO(4))(2).3CHCl(3).H(2)O,3, of optically active hexaaza triphenolic macrocycle H(3)L(1) were synthesized and crystallographically characterized. The cation [Zn(3)L(1)(micro-OAc)](+) structure of 1 and 2 closely resembles the trinuclear Zn(II) active site of P1 nuclease. The distorted tetrahedral geometry of Zn3 was successfully reproduced at Cu1 in complex 3. The complexes 2 and 3 cleave CT DNA at 37 and 50 degrees C.     

Phosphotyrosine phosphatases acting on band 3 in human erythrocytes of different age: PTP1B processing during cell ageing

The phosphorylation of tyrosine residues of human red blood cell (RBC) band 3 is regulated in vivo by constitutively active tyrosine-kinases (PTKs) and phosphotyrosine-phosphatases (PTPs), identified so far as, respectively, p72(syk) and p56/53(lyn), and PTP1B and SHPTP-2. Tyr-phosphorylation of band 3 increases upon reduction of cell volume as in hypertonic media or during Ca(2+)-induced membrane vesiculation. We show here that old RBCs display higher Tyr-phosphorylation levels of band 3 than younger cells under hypertonic conditions, at least in part due to the reduced cell volume of old RBCs, a condition of lowered threshold for activation of volume-sensitive PTKs. We have also analysed the membrane-bound PTP activity and the relative abundance of PTP1B (as the main membrane-associated PTP) in RBCs of different age. Immunodetection of PTP1B in purified ghost membranes revealed that the catalytic, N-terminal domain of the PTP is partially cleaved, in an age-dependent manner, from the membrane-bound domain, and it is lost during the preparation of ghost membranes. This suggests that erythrocytes may undergo in vivo activation of the Ca(2+)-dependent calpain system that proteolytically regulates PTP1B activity, as already documented for other cell types. On the other hand, the assay of the PTP activity that remains associated with the membranes of RBCs of different age indicated that the PTP undergoes oxidative inactivation that can be further differentiated into reversible and irreversible components.     

Chemiluminescent reactions of rare gas atoms,Rg(ns, 3P2, 3P1, 1P1) with N2O,SCO and SeCO: Spectroscopy and energy disposal in rare gas oxide,sulphide and selenide excimers

Chemiluminescence associated with excimer states of XeO, KrO, ArO, XeS and XeSe has been generated through the reaction of electronically excited rare gas atoms, Rg(ns, ³P₂, ³P₁, or ¹P₁) with N₂O, SCO, SCNH or SeCO. Branching ratios into the atom-transfer channels for reactions of Rg(³P₂) are < 1%. Experiments using a superthermal reagent beam of Xe(³P₂) indicate translational threshold behaviour for the reaction Xe(³P₂) + N₂O → (Xe⁺O⁻) + N₂. Estimates of the initial vibrational population distributions and spectroscopic parameters of XeO and KrO have been achieved through a preliminary analysis of their chemiluminescence spectra.     

Less is more when simulating unsulfated glycosaminoglycan 3D‐structure: Comparison of GLYCAM06/TIP3P,PM3‐CARB1/TIP3P,and SCC‐DFTB‐D/TIP3P predictions with experiment

The 3D‐structure of extracellular matrix glycosaminoglycans is central to function, but is currently poorly understood. Resolving this will provide insight into their heterogeneous biological roles and help to realize their significant therapeutic potential. Glycosaminoglycan chemical isoforms are too numerous to study experimentally and simulation provides a tractable alternative. However, best practice for accurate calculation of glycosaminoglycan 3D‐structure within biologically relevant nanosecond timescales is uncertain. Here, we evaluate the ability of three potentials to reproduce experimentally observed glycosaminoglycan monosaccharide puckering, disaccharide 3D‐conformation, and characteristic solvent interactions. Temporal dynamics of unsulfated chondroitin, chondroitin‐4‐sulfate, and hyaluronan β(1→3) disaccharides were simulated within TIP3P explicit solvent unrestrained for 20 ns using the GLYCAM06 force‐field and two semi‐empirical quantum mechanics methods, PM3‐CARB1 and SCC‐DFTB‐D (both within a hybrid QM/MM formalism). Comparison of calculated and experimental properties (vicinal couplings, nuclear Overhauser enhancements, and glycosidic linkage geometries) showed that the carbohydrate‐specific parameterization of PM3‐CARB1 imparted quantifiable benefits on monosaccharide puckering and that the SCC‐DFTB‐D method (including an empirical correction for dispersion) best modeled the effects of hexosamine 4‐sulfation. However, paradoxically, the most approximate approach (GLYCAM06/TIP3P) was the best at predicting monosaccharide puckering, 3D‐conformation, and solvent interactions. Our data contribute to the debate and emerging consensus on the relative performance of these levels of theory for biological molecules. © 2010 Wiley Periodicals, Inc. J Comput Chem, 2010