scispace - formally typeset
Search or ask a question

Showing papers in "ChemInform in 1997"


Journal ArticleDOI
TL;DR: The amorphous state is critical in determining the solid-state physical and chemical properties of many pharmaceutical dosage forms as mentioned in this paper and some of the most common methods that can be used to measure them.
Abstract: The amorphous state is critical in determining the solid-state physical and chemical properties of many pharmaceutical dosage forms. This review describes the characteristics of the amorphous state and some of the most common methods that can be used to measure them. Examples of pharmaceutical situations where the presence of the amorphous state plays an important role are presented. The application of our current knowledge to pharmaceutical formulation problems is illustrated, and some strategies for working with amorphous character in pharmaceutical systems are provided.

406 citations


Journal ArticleDOI
Russ Hille1

338 citations


Book ChapterDOI

306 citations


Journal ArticleDOI
TL;DR: Corma et al. as mentioned in this paper showed that the adsorption properties of zeolites can be controlled, and they can be varied from hydrophobic to hydrophilic type materials.
Abstract: It is possible to say that zeolites are the most widely used catalysts in industry. They are crystalline microporous materials which have become extremely successful as catalysts for oil refining, petrochemistry, and organic synthesis in the production of fine and speciality chemicals, particularly when dealing with molecules having kinetic diameters below 10 A. The reason for their success in catalysis is related to the following specific features of these materials:1 (1) They have very high surface area and adsorption capacity. (2) The adsorption properties of the zeolites can be controlled, and they can be varied from hydrophobic to hydrophilic type materials. (3) Active sites, such as acid sites for instance, can be generated in the framework and their strength and concentration can be tailored for a particular application. (4) The sizes of their channels and cavities are in the range typical for many molecules of interest (5-12 A), and the strong electric fields2 existing in those micropores together with an electronic confinement of the guest molecules3 are responsible for a preactivation of the reactants. (5) Their intricate channel structure allows the zeolites to present different types of shape selectivity, i.e., product, reactant, and transition state, which can be used to direct a given catalytic reaction toward the desired product avoiding undesired side reactions. (6) All of these properties of zeolites, which are of paramount importance in catalysis and make them attractive choices for the types of processes listed above, are ultimately dependent on the thermal and hydrothermal stability of these materials. In the case of zeolites, they can be activated to produce very stable materials not just resistant to heat and steam but also to chemical attacks. Avelino Corma Canos was born in Moncofar, Spain, in 1951. He studied chemistry at the Universidad de Valencia (1967−1973) and received his Ph.D. at the Universidad Complutense de Madrid in 1976. He became director of the Instituto de Tecnologia Quimica (UPV-CSIC) at the Universidad Politecnica de Valencia in 1990. His current research field is zeolites as catalysts, covering aspects of synthesis, characterization and reactivity in acid−base and redox catalysis. A. Corma has written about 250 articles on these subjects in international journals, three books, and a number of reviews and book chapters. He is a member of the Editorial Board of Zeolites, Catalysis Review Science and Engineering, Catalysis Letters, Applied Catalysis, Journal of Molecular Catalysis, Research Trends, CaTTech, and Journal of the Chemical Society, Chemical Communications. A. Corma is coauthor of 20 patents, five of them being for commercial applications. He has been awarded with the Dupont Award on new materials (1995), and the Spanish National Award “Leonardo Torres Quevedo” on Technology Research (1996). 2373 Chem. Rev. 1997, 97, 2373−2419

246 citations



Journal ArticleDOI

225 citations


Journal ArticleDOI
TL;DR: In this paper, four iridoid glucosides 1−4, named blumeosides A−D, were isolated from the methanolic stem-bark extract of Fagraea blumei G. (Loganiaceae).
Abstract: Four new iridoid glucosides 1–4, named blumeosides A–D, were isolated from the methanolic stem-bark extract of Fagraea blumei G. DON. (Loganiaceae). They were accompanied by the benzyl-alcohol derivative di-O-methylcrenatin (5) and the flavone C-glucoside swertisin (6). The structures of 1–4 were established by spectroscopic methods, including FAB-MS, and 1H- and 13C-NMR, and by alkaline hydrolysis. Blumeosides A (1) and C (3) are 10-O-(2,5-dihydroxytercphthalo) adoxosidic acid and 10-O-(2-hydroxyterephthalo)adoxosidic acid, respectively. In blumeosides B (4) and D (2), both carboxylic groups of the terephthalic-acid moiety are esterified by adoxosidic-acid units, Blumeosides A–D (1–4) inhibited bleaching of crocin induced by alkoxyl radicals. Blumeosides A (1) and D (2) also demonstrated scavenging properties towards the 2,2-diphenyl-1-picryl-hvdrazvl (CDPPH) radical in TLC autographic and spectrophotometric assays.

153 citations



Journal ArticleDOI
TL;DR: In this paper, the authors considered the physical basis of the echo attenuation of a Hahn spin-echo pulse sequence containing a magnetic field gradient pulse in each τ period to measure the displacement of the observed spins.
Abstract: Translational diffusion is the most fundamental form of transport in chemical and biochemical systems. Pulsed-field gradient nuclear magnetic resonance provides a convenient and noninvasive means for measuring translational motion. In this method the attenuation of the echo signal from a Hahn spin-echo pulse sequence containing a magnetic field gradient pulse in each τ period is used to measure the displacement of the observed spins. In the present article, the physical basis of this method is considered in detail. Starting from the Bloch equations containing diffusion terms, the (analytical) equation linking the echo attenuation to the diffusion of the spin for the case of unrestricted isotropic diffusion is derived. When the motion of the spin occurs within a confined geometry or is anisotropic, such as in in vivo systems, the echo attenuation also yields information on the surrounding structure, but as the analytical approach becomes mathematically intractable, approximate or numerical means must be used to extract the motional information. In this work, two common approximations are considered and their limitations are examined. Measurements in anisotropic systems are also considered in some detail. ©1997 John Wiley & Sons, Inc. Concepts Magn Reson 9: 299–336, 1997

146 citations


Journal ArticleDOI
TL;DR: A protein-bound metal site consists of one or more metal ions and all protein side chain and exogenous bridging and terminal ligands that define the first coordination sphere of each metal ion as discussed by the authors.
Abstract: For present purposes, a protein-bound metal site consists of one or more metal ions and all protein side chain and exogenous bridging and terminal ligands that define the first coordination sphere of each metal ion. Such sites can be classified into five basic types with the indicated functions: (1) structural -- configuration (in part) of protein tertiary and/or quaternary structure; (2) storage -- uptake, binding, and release of metals in soluble form: (3) electron transfer -- uptake, release, and storage of electrons; (4) dioxygen binding -- metal-O{sub 2} coordination and decoordination; and (5) catalytic -- substrate binding, activation, and turnover. The authors present here a classification and structure/function analysis of native metal sites based on these functions, where 5 is an extensive class subdivided by the type of reaction catalyzed. Within this purview, coverage of the various site types is extensive, but not exhaustive. The purpose of this exposition is to present examples of all types of sites and to relate, insofar as is currently feasible, the structure and function of selected types. The authors largely confine their considerations to the sites themselves, with due recognition that these site features are coupled to protein structure at all levels. In themore » next section, the coordination chemistry of metalloprotein sites and the unique properties of a protein as a ligand are briefly summarized. Structure/function relationships are systematically explored and tabulations of structurally defined sites presented. Finally, future directions in bioinorganic research in the context of metal site chemistry are considered. 620 refs.« less

134 citations


Journal ArticleDOI
TL;DR: In this article, a novel distance-cum-adjacency topological descriptor, termed as eccentric connectivity index, has been conceptualized, and its discriminating power has been investigated with regard to physical/biological properties of molecules.
Abstract: A novel, distance-cum-adjacency topological descriptor, termed as eccentric connectivity index, has been conceptualized, and its discriminating power has been investigated with regard to physical/biological properties of molecules. Correlation coefficients ranging from 95% to 99% were obtained using eccentric connectivity index in various datasets with regard to physical properties of diverse nature. These correlations were far superior to those correspondingly derived from the Wiener index. For structure−activity studies, a dataset, comprised of 94 substituted piperidinyl methyl ester and methylene methyl ester analogs as analgesic agents, was selected. Values of the eccentric connectivity index, the Wiener index, and Randic's molecular connectivity index were calculated, and active ranges were identified. Good correlations between topological descriptors and analgesic activity of these analogs were obtained. Eccentric connectivity index exhibited highest predictibility of the order of 86%. High discrimi...

Journal ArticleDOI
TL;DR: Preliminary screening performed at NCI showed that most derivatives exhibited a moderate to strong growth inhibition activity on various tumor panel cell lines between 10(-5) and 10(-4) Molar concentrations.

Journal ArticleDOI
TL;DR: In this paper, two diketopiperazine alkaloids, spirotryprostatins A and B, were isolated as new inhibitors of the mammalian cell cycle from the secondary metabolites of Aspergillus fumigatus through a separation procedure guided by cell cycle inhibitory activity.
Abstract: Two novel diketopiperazine alkaloids, spirotryprostatins A and B, were isolated as new inhibitors of the mammalian cell cycle from the secondary metabolites of Aspergillus fumigatus through a separation procedure guided by cell cycle inhibitory activity. The structures of spirotryprostatins A and B were determined by spectroscopic methods especially by detailed analyses of their 1H and 13C NMR spectra with the aid of 2D NMR techniques. Spirotryprostatins A and B had a novel structural skeleton with an unique spiro ring system and inhibited the cell cycle progression of tsFT210 cells at the G2/M phase with IC50 values of 197.5 μM and 14.0 μM, respectively.


Journal ArticleDOI
TL;DR: Some biochemical properties of certain of these compounds are outlined especially with reference to their causing inhibition of respiration in mitochondria, particularly in those organelles obtained from neoplastic tissue.
Abstract: This review outlines the chemistry and anticancer and cytotoxic properties of certain Mannich bases. It is divided into four parts. The first section summarizes briefly various investigations undertaken by other researchers of the chemical and pharmacological properties of a number of Mannich bases against neoplasms. This remaining portions of this review are summaries of work undertaken in this laboratory. The second part presents the following aspects of the anticancer properties of various Mannich bases namely differences in antileukemic activity between certain conjugated styryl ketones and the related Mannich bases, intramolecular cyclization of various acyclic Mannich bases and the effect on anticancer activity of such a process, prodrug approaches with a view to obtaining preferential toxicity to cancerous rather than normal cells and finally the effect on antineoplastic properties of introducing a second basic centre into these compounds. The third section summarizes the promising in vitro activities of different acyclic Mannich bases which are effective against certain the WiDr human colon cancer cells and the preparation of a group of Mannich bases which are effective against certain drug resistant malignant cells. The evidence for and evaluations of a theory proposed by one of the authors called sequential cytotoxicity is presented followed by one of the authors called sequential cytotoxicity is presented followed by a description of the very high cytotoxicity of some 4-piperidones; a group of compounds which may be regarded as cyclic Mannich bases. Finally , some biochemical properties of certain of these compounds are outlined especially with reference to their causing inhibition of respiration in mitochondria, particularly in those organelles obtained from neoplastic tissue

Journal ArticleDOI
TL;DR: In this article, the authors recommend that all synthetic chemists should always consider pressure as one of the routine variables available to them, along with temperature, solvent, reaction time, catalysts, and so forth.
Abstract: The recommendation is developed that all synthetic chemists should always consider pressure as one of the routine variables available to them, along with temperature, solvent, reaction time, catalysts, and so forth. Ideally, equipment should be available both in the 1–5 and 10–20 kbar range, the former for the habitual testing of all reaction steps under increased pressure, and the latter for the more unusual instances in which gigapascal pressures appear to force otherwise reluctant reactions. The hope is that synthetic chemists will learn to optimize yields and conversions with respect to pressure as well as the other variables, and to report the pressure used just as routinely as they report reaction times and temperatures now.


Journal ArticleDOI
TL;DR: In this paper, a structure model for the active site of tyrosinases was proposed by using hemocyanin structure as a template, and the model was compared with respect to enzymatic structure, primary, secondary and tertiary structure, domain structure, Cu binding sites, maturation mechanism and activation mechanism.
Abstract: Tyrosinases from various organisms are compared with respect to enzymatic structure, primary, secondary and tertiary structure, domain structure, Cu binding sites, maturation mechanism and activation mechanism. On the basis of these comparisons, and by using hemocyanin structure as a template, a structure model for the active site of tyrosinases is proposed.

Journal ArticleDOI
TL;DR: A survey of the use of cerium oxide and CeO2-containing materials as oxidation and reduction catalysts is presented in this paper, with a special focus on catalytic interaction with small molecules such as hydrogen, carbon monoxide, oxygen, and nitric oxide.
Abstract: Over the past several years, cerium oxide and CeO2-containing materials have come under intense scrutiny as catalysts and as structural and electronic promoters of heterogeneous catalytic reactions. Recent developments regarding the characterization of ceria and CeO2-containing catalysts are critically reviewed with a special focus towards catalyst interaction with small molecules such as hydrogen, carbon monoxide, oxygen, and nitric oxide. Relevant catalytic and technological applications such as the use of ceria in automotive exhaust emission control and in the formulation of SO x reduction catalysts is described. A survey of the use of CeO2-containing materials as oxidation and reduction catalysts is also presented.


Journal ArticleDOI
TL;DR: In this paper, self-ordering of the cell arrangement of the porous structure of anodic alumina has been studied in a sulfuric acid solution, and a highly ordered structure was obtained under anodization at a constant potential of 25 to 27 V.
Abstract: Self-ordering of the cell arrangement of the porous structure of anodic alumina has been studied in a sulfuric acid solution. Ordering of the cell arrangement was dependent on the applied potential, and a highly ordered structure was obtained under anodization at a constant potential of 25 to 27 V. Self-ordering of the porous structure proceeded with the growth of the oxide layer under anodization at an appropriate potential, and a porous film with an almost ideal hexagonal honeycomb structure was formed over an area of several micrometers after a long period of anodization.



Journal ArticleDOI
TL;DR: Fluids near their critical point have dissolving power comparable to that of liquids, are much more compressible than dilute gases, and have transport properties intermediate between gas-and liquid-like as mentioned in this paper.
Abstract: Fluids near their critical point have dissolving power comparable to that of liquids, are much more compressible than dilute gases, and have transport properties intermediate between gas-and liquid-like. This unusual combination of physical properties can be advantageously exploited in environmentally benign separation and reaction processes, as well as for new kinds of materials processing.

Journal ArticleDOI
TL;DR: Patani et al. as mentioned in this paper reviewed the use of bioisosteric replacements in drug design and provided an overview of the bioisosteres that incorporates sufficient detail to enable the reader to understand the concepts being delineated.
Abstract: Years of cumulative research can result in the development of a clinically useful drug, providing either a cure for a particular disease or symptomatic relief from a physiological disorder. A lead compound with a desired pharmacological activity may have associated with it undesirable side effects, characteristics that limit its bioavailability, or structural features which adversely influence its metabolism and excretion from the body. Bioisosterism represents one approach used by the medicinal chemist for the rational modification of lead compounds into safer and more clinically effective agents. The concept of bioisosterism is often considered to be qualitative and intuitive.1 The prevalence of the use of bioisosteric replacements in drug design need not be emphasized. This topic has been reviewed in previous years.2-5 The objective of this review is to provide an overview of bioisosteres that incorporates sufficient detail to enable the reader to understand the concepts being delineated. While a few popular examples of the successful use of bioisosteres have been included, the George Patani graduated with a B.Pharm. in 1992 from the College of Pharmaceutical Sciences, Mangalore University at Manipal, India. In 1996, he received his M.S. in Pharmaceutical Science at Rutgers University under the direction of Professor Edmond J. LaVoie. He is presently pursuing graduate studies in pharmaceutics. His current research interests are focused on drug design and controlled drug delivery.

Journal ArticleDOI
TL;DR: In this article, the authors showed that 9 would closely approximate the bioactive conformation of glutamate when acting at group 2 metabotropic glutamate receptors (mGluRs) in the rat cerebral cortical slice.
Abstract: 2-Aminobicyclo[3.1.0]hexane-2,6-dicarboxylic acid (9) was designed as a conformationally constrained analog of glutamic acid. For 9, the key torsion angles (τ1 and τ2) which determine the relative positions of the α-amino acid and distal carboxyl functionalities are constrained where τ1 = 166.9° or 202° and τ 2 = 156°, respectively. We hypothesized that 9 would closely approximate the proposed bioactive conformation of glutamate when acting at group 2 metabotropic glutamate receptors (mGluRs). The racemic target molecule (±)-9, its C2-diastereomer (±)-16, and its enantiomers (+)-9 (LY354740) and (−)-9 (LY366563) were prepared by an efficient, stereocontrolled, and high-yielding synthesis from 2-cyclopentenone. Our hypothesis that 9 could interact with high affinity and specificity at group 2 mGluRs has been supported by the observation that (±)-9 (EC50 = 0.086 ± 0.025 μM) and its enantiomer (+)-9 (EC50 = 0.055 ± 0.017 μM) are highly potent agonists for group 2 mGluRs in the rat cerebral cortical slice pre...

Journal ArticleDOI
TL;DR: In this paper, chlorogenic acid was identified as a specific inhibitor of the glucose-6-phosphate translocase component of this enzyme system in microsomes of rat liver.
Abstract: The enzyme system glucose-6-phosphatase (EC 3.1.3.9) plays a major role in the homeostatic regulation of blood glucose. It is responsible for the formation of endogenous glucose originating from gluconeogenesis and glycogenolysis. Recently, chlorogenic acid was identified as a specific inhibitor of the glucose-6-phosphate translocase component (Gl-6-P translocase) of this enzyme system in microsomes of rat liver. Glucose 6-phosphate hydrolysis was determined in the presence of chlorogenic acid or of new synthesized derivatives in intact rat liver microsomes in order to assess the inhibitory potency of the compounds on the translocase component. Variation in the 3-position of chlorogenic acid had only poor effects on inhibitory potency. Introduction of lipophilic side chain in the 1-position led to 100-fold more potent inhibitors. Functional assays on isolated perfused rat liver with compound 29i, a representative of the more potent derivatives, showed a dose-dependent inhibition of gluconeogenesis and glycogenolyosis, suggesting glucose-6-phosphatase as the locus of interference of the compound for inhibition of hepatic glucose production also in the isolated organ model. Gl-6-P translocase inhibitors may be useful for the reduction of inappropriately high rates of hepatic glucose output often found in non-insulin-dependent diabetes.

Book ChapterDOI
TL;DR: An overview is given of the results of the in vitro screening against MCF-7, a mammary tumor, and WiDr, a colon carcinoma, of several series of organotin compounds: diorganotin pyridinedicarboxylates, bis(salicylato)tetraorgano-distannoxanes, dIORganotin and triorganotin benzoates.
Abstract: An overview is given of the results of the in vitro screening against MCF-7, a mammary tumor, and WiDr, a colon carcinoma, of several series of organotin compounds: diorganotin pyridinedicarboxylates, bis(salicylato)tetraorgano-distannoxanes, diorganotin and triorganotin benzoates.

Journal ArticleDOI
TL;DR: A review of research directed toward developing enzymatic treatment systems for solid, liquid and hazardous wastes is presented in this article, where a large number of enzymes from a variety of different plants and microorganisms have been reported to play an important role in an array of waste treatment applications.
Abstract: The implementation of increasingly stringent standards for the dis- charge of wastes into the environment has necessitated the need for the develop- ment of alternative waste treatment processes. A review of research directed toward developing enzymatic treatment systems for solid, liquid and hazardous wastes is presented. A large number of enzymes from a variety of di†erent plants and microorganisms have been reported to play an important role in an array of waste treatment applications. Enzymes can act on speci-c recalcitrant pollutants to remove them by precipitation or transformation to other products. They also can change the characteristics of a given waste to render it more amenable to treatment or aid in converting waste material to value-added products. Before the full potential of enzymes may be realized, it is recommended that a number of issues be addressed in future research endeavors including the identi-cation and characterization of reaction by-products, the disposal of reaction products and reduction of the cost of enzymatic treatment.