Identification Of New Compounds Research Articles

Aminoglycoside microarrays to explore interactions of antibiotics with RNAs and proteins.

RNA is an important target for drug discovery efforts. Several clinically used aminoglycoside antibiotics bind to bacterial rRNA and inhibit protein synthesis. Aminoglycosides, however, are losing efficacy due to their inherent toxicity and the increase in antibiotic resistance. Targeting of other RNAs is also becoming more attractive thanks to the discovery of new potential RNA drug targets through genome sequencing and biochemical efforts. Identification of new compounds that target RNA is therefore urgent, and we report here on the development of rapid screening methods to probe binding of low molecular weight ligands to proteins and RNAs. A series of aminoglycosides has been immobilized onto glass microscope slides, and binding to proteins and RNAs has been detected by fluorescence. Construction and analysis of the arrays is completed by standard DNA genechip technology. Binding of immobilized aminoglycosides to proteins that are models for study of aminoglycoside toxicity (DNA polymerase and phospholipase C), small RNA oligonucleotide mimics of aminoglycoside binding sites in the ribosome (rRNA A-site mimics), and a large (approximately 400 nucleotide) group I ribozyme RNA is detected. The ability to screen large RNAs alleviates many complications associated with binding experiments that use isolated truncated regions from larger RNAs. These studies lay the foundation for rapid identification of small organic ligands from combinatorial libraries that exhibit strong and selective RNA binding while displaying decreased affinity to toxicity-causing proteins.

Twenty years of research into medicinal plants: Results and perspectives

Over the years 1981 to 2001 there has been a rapid evolution of research into medicinal plants. The major improvement has been the introduction of simple and predictive bioassays for bioactivity-guided isolation. Radical developments in separation methods have also taken place. Another important addition has been the development of hyphenated techniques involving HPLC: LC/UV, LC/MS, LC/MSn and LC/NMR. These are indispensable nowadays for the early detection and identification of new compounds in crude plant extracts. Hyphenated techniques allow an efficient targeted isolation approach for the discovery of new lead compounds. Other areas of increasing importance include the investigation of toxic constituents of plants and phytomedicines, and the effects of genetic modifications on plant secondary metabolites.

Role of 4-phenyl-3-buten-2-one in boar taint: identification of new compounds related to sensorial descriptors in pig fat.

The possible contribution of other compounds to the development of boar taint in fat samples with low concentrations of skatole and androstenone and classified as tainted was evaluated by GC-MS in the SCAN mode. Skatole and androstenone were determined by normal phase HPLC and GC-MS, respectively. For the identification of other compounds fat samples were purified with a gel filtration column and the second fraction was saponified at room temperature with KOH/3 N MeOH. 4-Phenyl-3-buten-2-one was the main compound identified in the fat samples, and its identification was corroborated by comparison with a standard solution obtained from a commercial source and by HPLC. The sensorial analysis of 4-phenyl-3-buten-2-one showed its possible contribution to boar taint. The possible contribution of phenol derivatives and short-chain fatty acids was also evaluated.

Cerebrolysin reduces microglial activation in vivo and in vitro: a potential mechanism of neuroprotection.

Neurotrophins, such as NGF, BDNF and NT-3 play a regulatory role on the function of microglial cells in vivo and in vitro, and the identification of new compounds with neurotrophic properties is becoming a new strategy for the prevention and/or treatment of neurodegenerative disorders. In this study we describe the use of two different models to demonstrate the ability of Cerebrolysin to reduce microglial activation. The results of these in vitro and in vivo studies indicate that Cerebrolysin might exert a neuroimmunotrophic activity reducing the extent of inflammation and accelerated neuronal death under pathological conditions such as those observed in neurodegenerative diseases.

Evaluation of an agonist index: affinity ratio for compounds active on muscarinic cholinergic M2 receptors.

A protocol for predicting full agonist, partial agonist, and antagonist profiles of compounds with M2 muscarinic cholinergic receptor activity was developed using radioligand binding assay techniques with [3H]-N-methyl scopolamine (NMS) and [3H]-Oxotremorine-M (Oxo-M) as radioligands. Full muscarinic cholinergic receptor agonists such as muscarine and oxotremorine-M expressed a high agonist index (> 3000 for M1 muscarinic cholinergic receptors and > 900 for M2 muscarinic cholinergic receptor), whereas muscarinic receptor antagonists (selective or non-selective) for different receptor subtypes gave a low (0.5-10) agonist index. Functional studies performed on preparations of guinea-pig ileum and heart were consistent with radioligand binding assay experiments. The above results suggest that similarly as already established for the M1 muscarinic cholinergic receptor subtype, evaluation of the [3H]-NMS/[3H]-Oxo-M ratio may provide useful information on the profile of compounds acting at the M2 muscarinic cholinergic receptor subtype. The availability of simple and predictive techniques for the characterization of muscarinic M2 cholinergic receptor agonists, may help the identification of new compounds in therapeutic areas in which stimulation or inhibition of this receptor is desirable.

Contribution to the Study of the Aromatic Potential of Three Muscat Vitis Vinifera Varieties: Identification of New Compounds

About 60 components of the free and bound fractions of the aroma of three Vitis vinifera grape cultivars (i.e., Muscat d'Alexandrie, Muscat d'Hambourg, and Muscat de Frontignan) were determined. Free and bound fractions were isolated by selective retention on a nonionic resin (Amberlite XAD-2). The free fraction was directly analyzed by means of gas chromatography and gas chromatography–mass spectrometry (GC and GC-MS). The analysis of the bound fraction was performed following two methods: (1) by enzymttic hydrolysis, to release the volatile aglycons and (2) by TFA (trifluoroacetylation) of the glycosidic compounds. Several glycosidic compounds were identified as glucosides, arabinosides, rutinosides, and apiosides, which constitute an important grape aroma reserve.

Theoretical and practical considerations in screening strategies for differentiation agents

Abstract This paper reviews strategies for identification of new compounds with differentiation inducing activity. The primary objective is to discriminate ‘lead’ compounds with novel mechanisms of action. Complementary to this is the need to generate a taxonomy of known compounds, identifying those with similar mechanisms, preferably in a way that provides clues as to the nature of those mechanisms. Experimental data suggest that the methods to do this are already to hand and that some existing search strategies are readily adapted to these objectives. The principal property required of the screen is that distinct mechanisms of induction produce different outcomes. Response patterns can thus be used to group drugs with similar mechanisms and hence identify novel activities. To be successful, such patterns have to be relatively insensitive to potency (so that agents with the same mechanism but different potency are classed together). Two strategies to achieve mechanism-sensitive response patterns are outlined, one based on the varied response capacities of multiple target cell types and another exploiting drug interaction patterns. With the former, the principle exploited is that the differences in the panel cells' capacities to respond depend on the components and assembly of their signal transduction and effector mechanisms for differentiation. With the latter, it is the varied and complex ways in which the components of the intracellular mechanism are assembled which provides distinctive interaction patterns, depending upon which components are the molecular targets of a particular pair of drugs. Pattern generation, analysis and optimisation of efficacy and cost/benefit are also discussed. Differentiation end-points are difficult to assess and cell number/mass may be more appropriate to high throughput designs. The problems of discriminating growth arrest due to differentiation, from other antiproliferative or simply cytotoxic effects are therefore considered and suggestions made for feasibility studies of these approaches.

Retinoids for the future: Investigational approaches for the identification of new compounds

One desired goal for future retinoid development is the dissociation of therapeutic benefit from teratogenic risk. It is not known if this result can be achieved, but increasing our understanding of the molecular mechanisms of retinoid action offers rational approaches to the attainment of this goal. The basis for these new approaches is the recent discovery of nuclear receptors for all-trans-retinoic acid and for the 9-cis form of retinoic acid. These receptors, like the steroid hormone receptors, are ligand-dependent transcription factors. Retinoids act by binding to these receptors and modulating specific gene pathways that ultimately control cell differentiation and development. Retinoic acid is required for normal embryonic development, and retinoic acid concentrations are regulated in the developing embryo. The malformations associated with in utero exposure to retinoids might be the result of inappropriate activation of specific receptors and inappropriate modulation of specific gene pathways. At least three nuclear receptors for all-trans-retinoic acid and three nuclear receptors for the 9-cis form of retinoic acid are known to exist, with the two receptor subfamilies interacting to form heterodimers. This multiplicity of receptors and receptor interactions suggests that differences may exist among receptors in the biologic effects they mediate. Although some retinoid ligands are not specific, others are highly selective for one particular receptor. Contrasting the effects of ligands with different specificities should increase understanding of the biologic responses associated with specific receptors and efforts to dissociate therapeutic activity from undesired effects.

A carbon 13‐NMR assignment study of a series of oxetanes derived from carbonyl compounds and furan and thiophene derivatives

AbstractThe assignment of the carbon‐13 nmr resonances of a series of oxetanes derived from the photoaddition of benzophenone and 2‐naphthaldehyde to furan and some of its methyl derivatives and of benzophenone to 2,5‐dimethylthiophene has been made. The assignments were made by chemical shift arguments, by the use of C‐13 labelling when required and different decoupling techniques. This information may be useful in the identification of new compounds with analogous carbon skeleton.