Characterization of in vivo metabolites of toad venom using liquid chromatography-mass spectrometry

The structures of in vivo metabolites of marinobufotoxin (marinobufagin 3-suberoylarginine ester), marinobufagin, or bufalin which are typical components of toad venom widely used as the traditional Chinese drug, Ch'an Su, are confirmed using authentic samples based on their liquid chromatography-mass spectrometric behavior. A rat is orally administered 2 mg of the previously mentioned components of toad venom, the serum is collected 30 min after the administration, extracted, and then characterized. Marinobufotoxin is hydrolyzed and further epimerized into 3-epimarinobufagin, but marinobufagin 3-hemisuberate is not detected. After the administration of marinobufagin, 3-epimarinobufagin is detected in both the male and female rats, but marinobufagin 3-sulfate is formed only in the female rats. Bufalin is metabolized to 3-epibufalin, which is found to undergo further conjugation resulting in its 3-glucuronide. Furthermore, 3-epibufalin 3-sulfate is formed only in the female rats.     

负载型三氧化钼催化剂表面结构和表面酸位的激光Raman光谱研究

测定了MoO3/γ-Al2O3、MoO3/TiO2、MoO3/SiO2的激光Raman谱. 通过MoO3/γ-Al2O3、MoO3/TiO2在吡啶吸附前后、氨水提取前后的谱图对比说明, 单层分散的MoO3, 即特征峰为～950cm^-^1的"二维聚钼酸"中钼的配位状态不是单一的,其中一种表面含钼物种(Mo-1)不吸附吡啶, 不溶于氨水, 不显示较强的表面酸性; 另一种表面含钼物种(Mo-2)可吸附吡啶, 溶于氨水, 与催化剂的表面酸位密切相关. 我们认为Mo-1为四面体配位的钼; Mo-2为八面体配位的钼. MoO3/SiO2中的MoO3能100%被氨水溶去, 其酸位数与表面Mo^6^+数之比接近1, 是由其中Mo-2的比例较高, 载体与活性组分之间的相互作用较弱这两个因素所造成的。     

稀土元素的电分析化学研究 X:钆-茜素红的极谱配合吸附波的研究

In a supporting electrolyte containing 2X10-4M Alizarin Red S, 0.1M NH3-NH4Cl and at pH 9.6, we obtained an adsorptive complex wave of gadolinium-Alizarin Bed S by single-sweep polarography. The peak potential of the derivative wave is -0.69V (S. C. E.). The limit of detection for gadolinium is 6X10-8M. We have determined the composition of the complex which is 1:3 GD-Alizarin Red S and confirmed that the wave is an adsorptive complex wave. The electrode processes may be presented as follows: Gd3+ + 3HL2- + 3NH3 = (GdL3)6- + 3(NH4)^+ (Chemical reaction) (GdL3)6- = (GdL3)ad6- (Surface process) The total electrochemical reaction is (GdL3)ad6- + 6e + 6(NH4)^+ = (Gd(LH2)3)ad6- + 6NH3     

顺反构型[Rh(NH3)3Cl]在室温水溶液中的行为兼论铂配合物的抗癌机理及药效

In this paper the behaviour of mer-and fac-(Rh(NH3)3Cl3) in aqueous solution at room temperature is reported. The experimental results show that some obvious differences exist between the properties of mer-and fac-(Rh(NH3)3Cl3) coordination compounds in aqueous solution at room temperature. The fac-(Rh(NH3)3Cl3) is relatively stable, and the mer-(Rh(NH3)3 Cl3) is unstable. When one of its Cl^- is replaced by H2O(RH(NH3)3)(OH)2Cl2)Cl is formed. The mechanism of anti-tumour action of platinum compounds is briefly discussed.     

A kinetic study of reactions of Et3ZnLi and di-tert-butyl ketone

An organozincate of composition Et3ZnLi and di-tert-butyl ketone react in toluene to form (after hydrolysis) ethyl-di-tert-butylmethanol. The rate is proportional to approximately [Et3ZnLi](-0.5)[ketone](1) when the initial concentration of Et3ZnLi is greater than that of the ketone but proportional to [Et3ZnLi](1)[ketone](-1) when the initial concentration of ketone is greater than that of Et3ZnLi. The rate of addition of Et3ZnK to di-tert-butyl ketone is <10(-4) that of Et3ZnLi.     

Structural stability and electronic state of transition metal trimers

Ground state geometries were searched for transition metal trimers Sc3, Y3, La3, Lu3, Ti3, Zr3, and Hf3 by density functional methods. For all the studied trimers, our calculation indicates that the ground state geometries are either equilateral triangle (Zr3 and Hf3) or near equilateral triangle (Ti3, Sc3, Y3, La3, and Lu3). For rare earth trimers Sc3, Y3, La3, and Lu3, isosceles triangle (near equilateral triangle) at quartet state is the ground state. Isosceles triangle at doublet state is the competitive candidate for the ground state. For Zr3 and Hf3, equilateral triangle at singlet state is the most stable. For Ti3, isosceles triangle (near equilateral triangle) at quintet state gives the ground state. For Sc3, Zr3, and Hf3, where experimental results are available, the predicted geometries are in agreement with experiment in which the ground state is equilateral triangle (Zr3) or fluxional (Sc3 and Hf3). For Y3, the calculated geometry is in agreement with experimental observation and previous theoretical study that Y3 is a bent molecule for the ground state. For La3, our calculation is in excellent agreement with previous theoretical study based on density functional methods.     

WO3在不同担体上的程序升温硫化研究

利用ＴＰＳ方法考察了ＷＯ３在γ－Ａｌ２Ｏ３，ＴｉＯ２－Ａｌ２Ｏ３及活性碳上的硫化过程，结果发现，随着ＷＯ２担载量的增加，表面Ｗ物种硫化峰的数目增加，表明ＷＯ３的的担载量超过一定量后，在这三种担体表面，都有几种Ｗ物种同时存在：ＷＯ３／ＴｉＯ２－Ａｌ２Ｏ３与ＷＯ３／Ａｌ２Ｏ３相比，当ＷＯ３担载量低于一个单层分布时，硫化温度明显降低，而超过一个单层分布后，两者的硫化温度相接近，表明ＴｉＯ２的调变作用对低     

Improved Synthesis of 3-Nitrophenylacetic Acid

In the development of certain work in our laboratory, we needed large quantities of 3-nitrophenylacetic acid. This material is very expensive commercially. It therefore became necessary to find a convenient and efficient process since none of the reported procedures is suitable for a large scale preparation of 3-nitrophenylacetic acid. In the first synthesis reported by Frederick et al.¹, 3-nitrobenzyl chloride was converted to 3-nitrophenylaceto-nitrile which was hydrolyzed to 3-nitrophenylacetic acid in 38% yield. The utility of this method for making large quantities of 3-nitrophenylacetic acid is restricted by the high cost of 3-nitrobenzyl halides. The second 2 method published by Jennings² is a multistep process starting with 3-nitrobenzaldehyde and the reported overall yield is 31%. This method also is not suitable for a large scale preparation due to the hazardous nature of the acid azide which is formed as one of the intermediates in this five step sequence. The third method describes the conversion of 3-nitroacetophenone to 3-nitrophenyl-acetic acid by willgerodt reaction.³ Although the starting material 3-nitroacetophenone is inexpensive but the reported yield of 3-nitrophenylacetic acid is only 7%. The high temperature required in the willgerodt reaction causes the reduction of nitro group by sulfur resulting in a bad mixture thus lowering the yield of nitrothio-morpholide (3) and making its isolation difficult.     

Cloning of BNIP3h, a member of proapoptotic BNIP3 family genes

Apoptosis is regulated by interaction of antiapoptotic Bcl-2 family proteins with various proapoptotic proteins, several of which are also members of the Bcl-2 family. BNIP3 (formerly NIP3) is a proapoptotic mitochondrial protein classified in the Bcl-2 family based on limited sequence homology-3 (BH3) domain and COOH-terminal transmembrane domain. Sequence comparison of BNIP3 has indicated that there are several BNIP3 human homologs of this protein, like BNIP3L, Nix and BNIP3. We have cloned a new member of BNIP3 family from the cDNA library prepared from human dermal papilla cells and designated as BNIP3h. BNIP3h shows substantial homology with other BNIP3 family proteins. BNIP3h induced apoptosis from 24 hours after transfection in MCF7 cell lines and its apoptosis inducing activity is extended until 72 hours after transfection.     

Addition of NH3 to Al3O3-

Recent computational studies on the addition of ammonia (NH3) to the Al3O3- cluster anion [A. Guevara-Garcia, A. Martinez, and J. V. Ortiz, J. Chem. Phys. 122, 214309 (2005)] have motivated experimental and additional computational studies, reported here. Al3O3- is observed to react with a single NH3 molecule to form the Al3O3NH3- ion in mass spectrometric studies. This is in contrast to similarly performed studies with water, in which the Al3O5H4- product was highly favored. However, the anion PE spectrum of the ammoniated species is very similar to that of Al3O4H2-. The adiabatic electron affinity of Al3O3NH3 is determined to be 2.35(5) eV. Based on comparison between the spectra and calculated electron affinities, it appears that NH3 adds dissociatively to Al3O3-, suggesting that the time for the Al3O3-NH3 complex to either overcome or tunnel through the barrier to proton transfer (which is higher for NH3 than for water) is short relative to the time for collisional cooling in the experiment.     

用量子力学研究膦化三氢化铝储氢材料在磷化氢催化作用下的释氢反应机理

利用量子力学第一原理研究了储氢材料膦化三氢化铝(AlH3PH3)在催化剂膦(PH3)作用下的释氢反应机理;首先在MP2/aug-cc-pVDZ水平上计算了反应物、过渡态和产物的几何构型和频率,进而利用内禀反应坐标理论确定了反应的最小能量路径,随后在CCSD(T)/aug-cc-pVDZ水平上对基于MP2优化的几何构型进行了能量校正.结果表明,AlH3PH3释氢的能垒高于Al―P键的离解能,而催化剂PH3不能降低AlH3PH3的释氢能垒.因此,需要寻找其他的催化剂以使AlH3PH3成为一种合用的储氢材料.     

Synthesis and biological activity of PTEN-resistant analogues of phosphatidylinositol 3,4,5-trisphosphate

The activation of phosphatidylinositol 3-kinase (PI 3-K) and subsequent production of PtdIns(3,4,5)P3 launches a signal transduction cascade that impinges on a plethora of downstream effects on cell physiology. Control of PI 3-K and PtdIns(3,4,5)P3 levels is an important therapeutic target in treatments for allergy, inflammation, cardiovascular, and malignant human diseases. We designed metabolically stabilized, that is, phosphatase resistant, analogues of PtdIns(3,4,5)P3 as probes for long-lived potential agonists or potential antagonists for cellular events mediated by PtdIns(3,4,5)P3. In particular, two types of analogues were prepared containing phosphomimetics that would be selectively resistant to the lipid 3-phosphatase PTEN. The total asymmetric synthesis of the 3-phosphorothioate-PtdIns(3,4,5)P3 and 3-methylenephosphonate-PtdIns(3,4,5)P3 analogues is described. These two analogues showed differential binding to PtdIns(3,4,5)P3 binding modules, and both were potential long-lived activators that mimicked insulin action in sodium transport in A6 cells.     

An Infrared Study of the Amine-Catalyzed Reaction of Methoxymethylsilanes with Silica

A thin film infrared technique was used to investigate the reaction of methoxysilanes and amines with the silica surface. The low-frequency region contains bands due to Si-O-Si modes that are used to distinguish between hydrogen-bonded and chemisorbed species. It is shown that the competitive adsorption of amines and CH(3)OSi(CH(3))(3) differs from the results obtained using (CH(3)O)(2)Si(CH(3))(2) or (CH(3)O)(3)SiCH(3). The monomethoxysilane does not displace preadsorbed triethylamine whereas the triethylamine is displaced from the surface by both (CH(3)O)(2)Si(CH(3))(2) and (CH(3)O)(3)SiCH(3). In the reverse sequence, the triethylamine displaces all three methoxysilanes on the surface. When 1:1 mixtures of methoxysilanes and triethylamine (or propylamine) are co-added to silica, the amine preferentially adsorbs and is only displaced by subsequent chemisorption of the silane. The implication of these results for using a two-step amine-catalyzed reaction of methoxysilanes on silica is discussed. Copyright 2000 Academic Press.     

α-Fe2O3掺杂对In2O3电导和气敏性能的影响

用化学共沉淀法制备了α Fe2O3掺杂的In2O3纳米晶微粉,研究了α Fe2O3掺杂对In2O3电导和气敏性能的影响. 结果表明, α Fe2O3和In2O3间可形成有限固溶体In2－xFexO3(0≤x≤0.40); Fe3＋对In2O3晶格中In3＋格位的部分取代,大大增强了阴阳离子间的结合力,导致材料中氧空位VO×数骤降、 自由电子的浓度变稀和电导下降. n(Fe3＋):n(In3＋)=5 :5的共沉淀粉于800 ℃下灼烧4 h所得的α Fe2O3掺杂In2O3传感器元件,对45 μmol•L－1 C2H5OH的灵敏度达54.0,为相同浓度干扰气体汽油的8倍多.     

Kinetics of the multichannel reaction of methanethiyl radical (CH3S*) with 3O2

The CH3S* + O2 reaction system is considered an important process in atmospheric chemistry and in combustion as a pathway for the exothermic conversion of methane-thiyl radical, CH3S*. Several density functional and ab initio computational methods are used in this study to determine thermochemical parameters, reaction paths, and kinetic barriers in the CH3S* + O2 reaction system. The data are also used to evaluate feasibility of the DFT methods for higher molecular weight oxy-sulfur hydrocarbons, where sulfur presents added complexity from its many valence states. The methods include: B3LYP/6-311++G(d,p), B3LYP/6-311++G(3df,2p), CCSD(T)/6-311G(d,p)//MP2/6-31G(d,p), B3P86/6-311G(2d,2p)//B3P86/6-31G(d), B3PW91/6-311++G(3df,2p), G3MP2, and CBS-QB3. The well depth for the CH3S* + 3O2 reaction to the syn-CH3SOO* adduct is found to be 9.7 kcal/mol. Low barrier exit channels from the syn-CH3SOO* adduct include: CH2S + HO2, (TS6, E(a) is 12.5 kcal/mol), CH3 + SO2 via CH3SO2 (TS2', E(a) is 17.8) and CH3SO + O (TS17, E(a) is 24.7) where the activation energy is relative to the syn-CH3SOO* stabilized adduct. The transition state (TS5) for formation of the CH3SOO adduct from CH3S* + O2 and the reverse dissociation of CH3SOO to CH3S* + O2 is relatively tight compared to typical association and simple bond dissociation reactions; this is a result of the very weak interaction. Reverse reaction is the dominant dissociation path due to enthalpy and entropy considerations. The rate constants from the chemical activation reaction and from the stabilized adduct to these products are estimated as functions of temperature and pressure. Our forward rate constant and CH3S loss profile are in agreement with the experiments under similar conditions. Of the methods above, the G3MP2 and CBS-QB3 composite methods are recommended for thermochemical determinations on these carbon-sulfur-oxygen systems, when they are feasible.     

超声辅助浸渍法制备高分散Pt/CMK-3-US加氢脱萘催化剂

以CMK-3介孔碳作为载体,分别采用传统浸渍法、超声辅助浸渍法、载体硝酸处理法和表面活性剂辅助浸渍法备了Pt/CMK-3、Pt/CMK-3-US、Pt/CMK-3-HNO₃和Pt/CMK-3-CTAB催化剂,并通过表征和催化性能评价进行研究。表征方法包括XRD、BET、SEM、TEM和H₂-TPR,结果表明Pt/CMK-3中Pt分散性最差,Pt/CMK-3-HNO₃和Pt/CMK-3-CTAB中Pt的分散度较好,但是HNO₃对介孔碳的孔道结构有破坏作用,且Pt/CMK-3-HNO₃和Pt/CMK-3-CTAB中的介孔碳的表面性质具有明显变化,只有超声法可以在很好地保持CMK-3的孔道结构和表面性质的基础上提高铂的分散度,Pt的粒径在3 nm左右。萘加氢催化性能评价结果表明Pt/CMK-3-US的催化加氢活性及产物选择性高于Pt/CMK-3,且明显高于Pt/CMK-3-HNO₃和Pt/CMK-3-CTAB。萘转化率可以达到98%以上,十氢萘选择性可以达到95%以上。     

超声辅助浸渍法制备高分散Pt/CMK-3-US加氢脱萘催化剂

以CMK-3介孔碳作为载体,分别采用传统浸渍法、超声辅助浸渍法、载体硝酸处理法和表面活性剂辅助浸渍法备了Pt/CMK-3、Pt/CMK-3-US、Pt/CMK-3-HNO_3和Pt/CMK-3-CTAB催化剂,并通过表征和催化性能评价进行研究。表征方法包括XRD、BET、SEM、TEM和H2-TPR,结果表明Pt/CMK-3中Pt分散性最差,Pt/CMK-3-HNO_3和Pt/CMK-3-CTAB中Pt的分散度较好,但是HNO_3对介孔碳的孔道结构有破坏作用,且Pt/CMK-3-HNO_3和Pt/CMK-3-CTAB中的介孔碳的表面性质具有明显变化,只有超声法可以在很好地保持CMK-3的孔道结构和表面性质的基础上提高铂的分散度,Pt的粒径在3 nm左右。萘加氢催化性能评价结果表明Pt/CMK-3-US的催化加氢活性及产物选择性高于Pt/CMK-3,且明显高于Pt/CMK-3-HNO_3和Pt/CMK-3-CTAB。萘转化率可以达到98%以上,十氢萘选择性可以达到95%以上。     

Radiolytic degradation of TBP-HNO3 system: Gas chromatographic determination of radiation chemical yields of n-Butanol and nitrobutane

Radiolytic degradation of the TBP-HNO₃ system has been studied for the radiation dose range of 19.8 to 262 kGy by the gas chromatographic method. n-Butanol and nitrobutane formed due to irradiation have been identified and estimated in pure TBP, TBP-3M HNO₃ extract and TBP-5M HNO₃ extract. The G-values (radiation chemical yields) of n-butanol are determined to be 0.28, 0.77 and 0.47 for a pure TBP, TBP-3M HNO₃ extract and TBP-5M HNO₃ extract, respectively. The G-values of nitrobutane (1-nitrobutane) are 0.55 and 1.09 for TBP-3M HNO₃ extract and TBP-5M HNO₃ extract. It is found than G(n-butanol) is less for TBP-5M HNO₃ extract than for TBP-3M HNO₃ extract, while G(nitrobutane) is grater for TBP-5M HNO₃ extract than for TBP-3M HNO₃ extract. This is explained on the basis of the formation of TBP.HNO₃ species and the role played by nitric acid in the TBP phase.     

Effect of 3-hydroxyproline residues on collagen stability

Collagen is an integral part of many types of connective tissue in animals, especially skin, bones, cartilage, and basement membranes. A fibrous protein, collagen has a triple-helical structure, which is comprised of strands with a repeating Xaa-Yaa-Gly sequence. l-Proline (Pro) and 4(R)-hydroxy-l-proline (4-Hyp) residues occur most often in the Xaa and Yaa positions. The 4-Hyp residue is known to increase markedly the conformational stability of a collagen triple helix. In natural collagen, a 3(S)-hydroxy-l-proline (3-Hyp) residue occurs in the sequence: 3-Hyp-4-Hyp-Gly. Its effect on collagen stability is unknown. Here, two host-guest peptides containing 3-Hyp are synthesized: (Pro-4-Hyp-Gly)(3)-3-Hyp-4-Hyp-Gly-(Pro-4-Hyp-Gly)(3) (peptide 1) and (Pro-4-Hyp-Gly)(3)-Pro-3-Hyp-Gly-(Pro-4-Hyp-Gly)(3) (peptide 2). The 3-Hyp residues in these two peptides diminish triple-helical stability in comparison to Pro. This destabilization is small when 3-Hyp is in the natural Xaa position (peptide 1). There, the inductive effect of its 3-hydroxyl group diminishes slightly the strength of the interstrand 3-HypC=O.H-NGly hydrogen bond. The destabilization is large when 3-Hyp is in the nonnatural Yaa position (peptide 2). There, its pyrrolidine ring pucker leads to inappropriate mainchain dihedral angles and interstrand steric clashes. Thus, the natural regioisomeric residues 3-Hyp and 4-Hyp have distinct effects on the conformational stability of the collagen triple helix.     

Density functional study of molecular properties of hydrazoic acid and methyl azide

Density functional calculations for hydrazoic acid HN₃ and methyl azide CH₃N₃ and for the respective singly ionized structures HN⁺₃ and CH₃N⁺₃ are reported. An analysis of the electrostatic solvent effects, based on the self-consistent reaction field approach, on the molecular properties and conformational equilibrium of CH₃N₃ is also reported. The results are sensitive to the basis set quality and show some dependence on the different representations for the exchange-correlation functions. For HN₃ very good agreement with experiment is observed for several properties, such as the geometry, dipole moment, vibrational frequencies and for the adiabatic first ionization energy. For CH₃N₃ the energy difference between eclipsed (ec) and staggered (st) conformers (δ_ec-st) is 2.5 kJ mol⁻¹, in good agreement with the experimental value (2.9 kJ mol⁻¹). However, for CH₃N⁺₃, δ_ec-st is −3.2 kJ mol⁻, reflecting a significant modification of the methyl group rotational potential after ionization. Solvent effects on the molecular properties of CH₃N₃ are important when it is solvated in a polar medium. The most significant modifications concern the dipole moment and the frequencies related to the CH₃ symmetric stretch and torsion vibrational modes.