Camptothecin and its analogues: a review on their chemotherapeutic potential

Topoisomerase I (Topo-I) is a major target for anticancer drug discovery and design. As a result, Topo-I inhibitors constitute an important class of the current anticancer drugs. To date, all of the Topo-I inhibitors that have been clinically evaluated are analogues of camptothecin (CPT), an extract of the Chinese tree Camptotheca acuminata. CPT has shown significant antitumor activity to lung, ovarian, breast, pancreas and stomach cancers. In this article the, phytochemical aspect, and various structural modifications are comprehensively reviewed as in rings A, B, C, D and E. Biological activity of camptothecin, other than anticancer, reported till the year 2003 has also been discussed.     

Asparagus racemosus: a review on its phytochemical and therapeutic potential

Asparagus racemosus (Willd.) is a widely found medicinal plant in tropical and subtropical parts of India. The therapeutic applications of this plant have been reported in Indian and British Pharmacopoeias and in traditional system of medicine, such as Ayurveda, Unani and Siddha. The crude, semi-purified and purified extracts obtained from different parts of this plant have been useful in therapeutic applications. Numerous bioactive phytochemicals mostly saponins and flavonoids have been isolated and identified from this plant which are responsible alone or in combination for various pharmacological activities. This review aims to give a comprehensive overview of traditional applications, current knowledge on the phytochemistry, pharmacology and overuse of A. racemosus.     

Flavonoids biosynthesis in plants and its further analysis by capillary electrophoresis

Flavonoids represent an important bioactive component in plants. Accumulation of flavonoids often occurs in plants subjected to abiotic stresses, including the adaptation of plants to the environment and in overcoming their stress conditions. This fact makes their analysis and determination an attractive field in food science since they can give interesting information on the quality and safety of foods. In this study, we discuss reports on plants flavonoids biosynthesis against abiotic stresses and advances in analytical capillary electrophoresis used for their identification and quantification in plants.     

Behaviour of ruthenium in nitric media (HLLW) in reprocessing plants: a review and some perspectives

Journal of Radioanalytical and Nuclear Chemistry - The reprocessing of spent nuclear fuel produces high level liquid waste (HLLW). Due to the decay heat, the concentrated nitric solutions...     

基于TCGA数据分析UHRF1在低级别胶质瘤中的表达与预后

为筛选胶质瘤外泌体中参与肿瘤迁移的差异蛋白,寻找可能抑制肿瘤细胞迁移的作用靶点. 本试验分别对具有不同迁移能力的A172、U251胶质瘤细胞系培养上清液进行了差异性探究. 结果显示,A172条件培养基具有更强的迁移促进作用,而外泌体为促进肿瘤迁移的主要成分. 随后利用串联质量标签（tandem mass tag,TMT）定量质谱法对其外泌体进行的蛋白质组学分析发现,差异蛋白（倍数改变≥2）主要富集于核糖体、间隙连接、泛素介导的蛋白降解三个KEGG（kyoto encyclopedia of genes and genomes）信号通路. 通过分析共获得了50种具有显著表达差异的外泌体蛋白,可作为胶质瘤的外泌体检测标志物及抑制肿瘤细胞迁移的潜在作用靶点.     

Research on the correlation between the Pummerer reaction and penicillin biosynthesis (review)

Research on the correlation between the Pummerer reaction mechanism and -lactam formation during penicillin biosynthesis is discussed based on our silicon-induced asymmetric Pummerer type reaction.Faculty of Pharmaceutical Sciences, Toyama Medical and Pharmaceutical University, Sugitani 2630, Toyama 930-0194, Japan. Graduate School of Pharmaceutical Sciences, Osaka University, 1–6 Yamada-oka, Suita, Osaka 565-0871, Japan. Published in Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1463–1474, November, 1998.     

Molybdenum cofactor biosynthesis in plants and humans

The transition element molybdenum (Mo) needs to be complexed by a special cofactor in order to gain catalytic activity. With the exception of bacterial Mo-nitrogenase, where Mo is a constituent of the FeMo-cofactor, Mo is bound to a pterin, thus forming the molybdenum cofactor Moco, which in different variants is the active compound at the catalytic site of all other Mo-containing enzymes. The biosynthesis of Moco involves the complex interaction of six proteins and is a process of four steps, which also requires reducing equivalents, iron, ATP and probably copper. After its synthesis, Moco is distributed to the apoproteins of Mo-enzymes by Moco–carrier/binding proteins that also participate in Moco-insertion into the cognate apoproteins. A deficiency in the biosynthesis of Moco has lethal consequences for the respective organisms. In humans, Moco deficiency is a severe inherited inborn error in metabolism resulting in severe neurodegeneration in newborns and causing early childhood death. Due to our better understanding of the chemistry of Moco synthesis, a first therapy has been brought to the clinic.     

Dichlorogallane (HGaCl(2))(2): its molecular structure and synthetic potential

Dichlorogallane (HGaCl(2))(2) is readily prepared from gallium trichloride and triethylsilane in quantitative yield. Its crystal structure has been determined by single crystal X-ray diffraction. In the chlorine-bridged dimers of crystallographically imposed C(2h) symmetry, the terminal hydrogen atoms are in trans positions. In the reaction with 2 equiv of triethylphosphine, the mononuclear complex (Et(3)P)GaHCl(2) is formed. Thermal decomposition of (HGaCl(2))(2) affords hydrogen gas and quantitative yields of "GaCl(2)" as mixed-valent Ga[GaCl(4)]. Treatment of this product with triethylphosphine gives the symmetrical, Ga-Ga-bonded gallium(II) complex [GaCl(2)(PEt(3))](2) with an ethane-type structure and with the phosphine ligands in a single-trans conformation. The corresponding [GaBr(2)(PEt(3))](2) complex is prepared from Ga[GaBr(4)] and has an analogous structure. (Et(3)P)GaCl(3) has been synthesized and structurally characterized as a reference compound.     

Catalytic pyrolysis of Phragmites (reed): Investigation of its potential as a biomass feedstock

In this paper, thermogravimetry, TG, and pyrolysis are used for the thermochemical evaluation of the common reed (Pragmites australis) as a candidate biomass feedstock. The TG analysis indicated that the material loses 4% of its weight below 150 °C through dehydration. The main decomposition reaction occurs between 200 and 390 °C. The rate of weight loss, represented by the derivative thermogravimetric, DTG, signal indicated a multi-step reaction. Kinetic analysis helped in the resolution of the temperature ranges of the overlapping steps. The first step corresponds to the degradation of the hemi-cellulosic fraction and the second to the cellulosic fraction degradation. The TG and DTG signals of reed samples treated with increasing concentration of potassium carbonate (0.6–10 wt%) indicated a catalytic effect of the salt on reed decomposition. The temperature of maximum weight loss rate, DTGmax, exponentially decreased with increasing catalyst content, whilst the initial temperature of the decomposition decreased linearly. The pyrolysis studies were carried out in a Pyrex vertical reactor with sintered glass disc to hold the sample and to aid the fluidization with the nitrogen stream flowing upwards. The reactor was connected to a cyclone and condenser and a gas sampling device. Tar and char are collected and weighed. The gas chromatographic analysis of the evolved gases demonstrated the effect of pyrolysis temperature (400, 450, and 500 °C) on their composition. The temperature increase favors the yields of hydrocarbons, carbon monoxide and hydrogen at the expense of methanol and carbon dioxide. Similarly, reed samples treated with K2CO3 at 10 wt% were pyrolyzed and analyzed. Comparisons for the various parameters (yields, gas composition and carbon–hydrogen recovery) between the untreated and catalyzed reed conversion were also made.     

Inter-ring rotational potential of biphenyl and its effect on poly(p-phenylene)

Detailed ab initio studies have been done on the inter-ring torsional states of the biphenyl molecule using self-consistent field molecular orbital method. The potential goes through a minimum at an angle of 38°. The height of the potential barrier for the coplanar state is 2.01 kcal/mol. When the phenyl rings are perpendicular to each other, this height increases to 2.37 kcal/mol. The role of correlation and polarization is found to be important. The shape of the potential suggests that polyparaphenylene may possibly exist as a super helix.     

Flicker noise spectroscopy and its application: Information hidden in chaotic signals (review)

Fundamentals of flicker noise spectroscopy (FNS), a general phenomenological approach to analyzing dynamics and structure of complex nonlinear systems by extracting information contained in chaotic signals of diverse nature generated by such systems, are presented. The primary idea of FNS is to disclose information hidden in correlation links which are present in a sequence of various irregularities (spikes, jumps, discontinuities in derivatives of different orders) that occur in the measured dynamic variables at all levels of spatiotemporal hierarchy of systems under study. The information is derived from power spectra S(f) (f, frequency) and transient difference moments Φ^(p)(τ)(τ, time delay parameter) of different orders p. The procedures of averaging over time interval T, which are introduced in FNS when computing S(f) and Φ^(p)(τ), differ from the procedures of averaging in the Gibbs approach. In the latter case, due to the adoption of the ergodic hypothesis, the average values of dynamic quantities over time are replaced by the average values of the same quantities over a statistical ensemble. It came to pass that the Φ^(p)(τ) functions are formed exclusively by jumps of a dynamic variable on different spatiotemporal levels of the system’s hierarchy, whereas the formation of S(f) is contributed to by spikes and jumps. The informative parameters extracted from S(f) and Φ^(p)(τ) describe correlation times and characterize loss of “memory” (correlation links) in these correlation time intervals for the “spike” and “jump” irregularities. These parameters can be determined using the expressions derived for the case of steady-state evolution. Here the “steady state” implies an evolution state that is characterized by the same values of informative parameters on every level of the system’s hierarchy. In contrast to the scaling self-similarity in theory of fractals and renormgroup, FNS introduces a multiparametric self-similarity for the S(f) and Φ^(p)(τ) functions, which is generally characterized by a set of parameters rather than one scaling factor. The S(f) and Φ⁽²⁾(τ) functions which are related to different types of information may be viewed, in the steady-state case, as fluctuation-dissipation relations that complement each other informatively. Examples of such generalized relations are presented for fluctuations of electric voltage under open-circuit conditions (the Nyquist theorem), the Levy diffusion, the hydrodynamic fluctuations at fully developed turbulence, and the flicker noise fluctuations of the electric current density in electron-conducting systems. To analyze the dynamics of non-steady processes, formulas are presented for calculating nonstationarity indicators (factors) and estimating time instants when most noticeable changes occur in systems under study, including those preceding catastrophic evolution changes. The studies carried out to date show that the FNS method can be used in solving problems of three types. The first is the determination of parameters or patterns that characterize the dynamics or specific features of structural organization of open complex systems. The second involves search for precursors of sharpest changes in the states of various open dissipative systems on the basis of available information conceming the dynamics of such systems. And the third problem concerns the dynamics of redistribution of perturbations in distributed systems. It is solved by analyzing dynamic correlations in chaotic signals that are measured simultaneously at different points in space. The review demonstrates some applications of the FNS methodology. In particular, it considers some physicochemical and natural processes the data for which were obtained from electrochemical and biological measurements.     

Polyketide folding in higher plants: biosynthesis of the phenylanthraquinone knipholone

The biosynthesis of knipholone, as an axially chiral phenylanthraquinone, in higher plants was examined by feeding experiments with [13C2]-labeled precursors. [13C2]-Acetate and advanced synthetic intermediates were fed to sterile cultures of Kniphofia pumila (Asphodelaceae), with subsequent NMR analysis on the isolated natural product involving 2D INADEQUATE and SELINQUATE experiments. Due to its uneven number of carbon atoms, and because of its uncertain decarboxylation site, the "northern" part of the molecule (i.e., the chrysophanol portion) might originate from four different cyclization modes. According to the labeling pattern of the product isolated after incorporation, this anthraquinone part of knipholone is formed by the so-called F folding mode (originally established for fungi). The acetophenone part of the molecule, which does not undergo a decarboxylation reaction, originates from four acetate units. The surprising lack of randomization of the intact [13C2] units in this "southern" part reveals the absence of a free symmetric intermediate as initially anticipated. This is in agreement with the intact incorporation of the "authentic" southern molecular portion, 4,6-dihydroxy-2-methoxyacetophenone, while the corresponding symmetrical candidate trihydroxyacetophenone was clearly not incorporated, showing that the O-methylation of the freshly cyclized tetraketide is the step that prevents symmetrization of the acetophenone.     

Electrocatalysis and pH (a review)

The factors determining pH effects on principal catalytic reactions in low-temperature fuel cells (oxygen reduction, hydrogen oxidation, and primary alcohols oxidation) are analyzed. The decreasing of hydrogen oxidation rate when passing from acidic electrolytes to basic ones was shown to be due to the electrode surface blocking by oxygen-containing species and changes in the adsorbed hydrogen energy state. In the case of oxygen reduction, the key factors determining the process’ kinetics and mechanism are: the O₂ adsorption energy, the adsorbed molecule protonation, and the oxygen reaction thermodynamics. The process’ high selectivity in acidic electrolytes at platinum electrodes is caused by rather high Pt-O₂ bond energy and its protonation. The passing from acidic electrolytes to basic ones involves a decrease in the oxygen adsorption energy, both at platinum and nonplatinum catalysts, hence, in the selectivity of the oxygen-to-water reduction reaction. The increase in the methanol and ethanol oxidation rate in basic media, as compared with acidic ones, is due to changes in the reacting species’ structure (because of the alcohol molecules dissociation) on the one hand, and active OH_ads species inflow to the reaction zone, on the other hand. In the case of ethanol, the above-listed factors determine the process’ increased selectivity with respect to CO₂ at higher pHs. Based on the survey and valuation, priority guidelines in the electrocatalysis of commercially important reactions are formulated, in particular, concepts of electrocatalysis at nonplatinum electrode materials that are stable in basic electrolytes, and approaches to the practical control of the rate and selectivity of oxygen reduction and primary alcohols oxidation over wide pH range.     

Chemistry of silver(III) and some of its compounds: A review

Chemistry of Ag(III), as of other transition elements with higher oxidation state(s), is important as its compounds are effectively used as oxidants, catalysts, fluorinating agents, etc. Some basic chemical properties of Ag(III) and up to date report of several Ag(III) compounds are discussed in this present review.     

Combinatorial atmospheric pressure chemical vapor deposition (cAPCVD): a route to functional property optimization

We demonstrate how combinatorial atmospheric pressure chemical vapor deposition (cAPCVD) can be used as a synthetic tool for rapidly optimizing the functional properties of thin-films, by analyzing the self-cleaning properties of tungsten doped anatase as an example. By introducing reagents at separate points inside the reactor, a tungsten/titanium compositional gradient was formed and a diverse range of film growth conditions were obtained. By partially mixing the metal sources, a combinatorial film with a compositional profile that varied primarily in the lateral plane was synthesized. A combinatorial thin-film of anatase TiO(2) doped with an array of tungsten levels as a solid solution ranging from 0.38-13.8 W/Ti atom % was formed on a single glass substrate. The compositional-functional relationships were understood through comprehensively analyzing combinatorial phase space, with 200 positions investigated by high-throughput methods in this study. Physical and functional properties, and their compositional dependencies, were intercorrelated. It was found that increases in photocatalytic activity and conductivity were most highly dependent on film crystallinity within the 0.38-13.8 atom % W/Ti doping regime. However, enhancements in photoinduced surface wetting were primarily dependent on increases in preferred growth in the (211) crystal plane.     

Recent and potential developments in the analysis of urine: a review

Analysis of urine is a widely used diagnostic tool that traditionally measured one or, at most, a few metabolites. However, the recognition of the need for a holistic approach to metabolism led to the application of metabolomics to urine for disease diagnostics. This review looks at various aspects of urinalysis including sampling and traditional approaches before reviewing recent developments using metabolomics. Spectrometric approaches are covered briefly since there are already a number of very good reviews on NMR spectroscopy and mass spectrometry and other spectrometries are not as highly developed in their applications to metabolomics. On the other hand, there has been a recent surge in chromatographic applications dedicated to characterising the human urinary metabolome. While developments in the analysis of urine encompassing both classical approaches of urinalysis and metabolomics are covered, it must be emphasized that these approaches are not orthogonal - they both have their uses and are complementary. Regardless, the need to normalise analytical data remains an important impediment.     

Ion-exchange measurement in biological samples by (p,X) and (p,p) reactions

A method of analysis by ion-exchange in biological samples using (p, X) reactions and back-scattering of charged particles is proposed. Sensitivity and rapidity are the principal qualities of this method.