Natural products: chemical instruments to apprehend biological symphony

As a striking variety of biological activities are elicited by natural products, these chemicals have been used for decades to study biological phenomena. Understanding how these products interfere with normal cell functions at a molecular level led to a wide range of discoveries including new signaling pathways and proteins. Moreover, as natural products often act as chemical inhibitors, such studies often allow the identification of their binding partners as relevant targets for drug design. This article aims to emphasize how natural products or engineered analogs can be used as chemical tools to apprehend some biological problems from the point of view of a chemical biologist.     

Physico-chemical processes in imidazolium ionic liquids

Among the various properties exhibited by ionic liquids (ILs)--especially those based on the imidazolium cation-their inherent ionic patterns, very low vapour pressure and pronounced self-organization in the solid, liquid and even in the gas phase are particularly interesting since this allows the use of these fluids as alternative and complementary media to classical organic solvents and water in many applications. Hence, reaction paths that involve charge-separated intermediates or transition states are accelerated--by lowering the activation barrier-in the presence of ILs when compared with those performed in classical organic solvents. It is also possible, for example, to observe, by electrochemical methods, transient species (ionic and radical) that are otherwise undetectible in water or in molecular organic solvents and to investigate the interactions and behaviour of molecular, biological and macromolecular species in solution using physical and chemical methods which require special conditions such as high-vacuum, and which have been traditionally limited to solid state chemistry.     

Inedible mushrooms: a good source of biologically active substances

In the course of our investigation on biologically active substances from inedible mushrooms in Japan, Germany, and Vietnam, we studied the chemical constituents of 22 species belonging to five families: Scutigeraceae, Polyporaceae, Xylariaceae, Thelephoraceae, and Paxillaceae. Various types of chemical substances were purified and characterized based on the modern spectroscopic methods and also on chemical reactions. These metabolites have shown a broad activity in many biological systems, such as antimicrobial, nematicidal, inhibition of NO production, anti-human immunodeficiency virus, tumor necrosis factor-alpha, and antioxidant activities. These isolated metabolites did not only show interesting activities, but also are employed as chemical markers supported for chemosystematics of these families. This review paper deals with the chemical constituents of 22 species, their biological activities, and also a discussion on chemosystematics.     

Synthesis and bioactivity of secondary metabolites from marine sponges containing dibrominated indolic systems

Marine sponges. (e.g., Hyrtios sp., Dragmacidin sp., Aglophenia pleuma, Aplidium cyaneum, Aplidium meridianum.) produce bioactive secondary metabolites involved in their defence mechanisms. Recently it was demonstrated that several of those compounds show a large variety of biological activities against different human diseases with possible applications in medicinal chemistry and in pharmaceutical fields, especially related to the new drug development process. Researchers have focused their attention principally on secondary metabolites with anti-cancer and cytotoxic activities. A common target for these molecules is the cytoskeleton, which has a central role in cellular proliferation, motility, and profusion involved in the metastatic process associate with tumors. In particular, many substances containing brominated indolic rings such as 5,6-dibromotryptamine, 5,6-dibromo-N-methyltryptamine, 5,6-dibromo-N-methyltryptophan (dibromoabrine), 5,6-dibromo-N,N-dimethyltryptamine and 5,6-dibromo-L-hypaphorine isolated from different marine sources, have shown anti-cancer activity, as well as antibiotic and anti-inflammatory properties. Considering the structural correlation between endogenous monoamine serotonin with marine indolic alkaloids 5,6-dibromoabrine and 5,6-dibromotryptamine, a potential use of some dibrominated indolic metabolites in the treatment of depression-related pathologies has also been hypothesized. Due to the potential applications in the treatment of various diseases and the increasing demand of these compounds for biological assays and the difficult of their isolation from marine sources, we report in this review a series of recent syntheses of marine dibrominated indole-containing products.     

Nanoparticles,Proteins, and Nucleic Acids: Biotechnology Meets Materials Science

Based on fundamental chemistry, biotechnology and materials science have developed over the past three decades into today's powerful disciplines which allow the engineering of advanced technical devices and the industrial production of active substances for pharmaceutical and biomedical applications. This review is focused on current approaches emerging at the intersection of materials research, nanosciences, and molecular biotechnology. This novel and highly interdisciplinary field of chemistry is closely associated with both the physical and chemical properties of organic and inorganic nanoparticles, as well as to the various aspects of molecular cloning, recombinant DNA and protein technology, and immunology. Evolutionary optimized biomolecules such as nucleic acids, proteins, and supramolecular complexes of these components, are utilized in the production of nanostructured and mesoscopic architectures from organic and inorganic materials. The highly developed instruments and techniques of today's materials research are used for basic and applied studies of fundamental biological processes.     

Chemoproteomic Evaluation of the Polyacetylene Callyspongynic Acid

Polyacetylenes are a class of alkyne‐containing natural products. Although potent bioactivities and thus possible applications as chemical probes have already been reported for some polyacetylenes, insights into the biological activities or molecular mode of action are still rather limited in most cases. To overcome this limitation, we describe the application of the polyacetylene callyspongynic acid in the development of an experimental roadmap for characterizing potential protein targets of alkyne‐containing natural products. To this end, we undertook the first chemical synthesis of callyspongynic acid. We then used in situ chemical proteomics methods to demonstrate extensive callyspongynic acid‐mediated chemical tagging of endoplasmic reticulum‐associated lipid‐metabolizing and modifying enzymes. We anticipate that an elucidation of protein targets of natural products may serve as an effective guide to the development of subsequent biological assays that aim to identify chemical phenotypes and bioactivities.     

Structural Features and Biological Activities of Bioactive Compounds from Fortunella margarita(Lour.) Swingle:A Review

Fortunella margarita(Lour.) Swingle, commonly known as kumquat, is the smallest citrus fruit. It thrives in southeastern China and is widely cultivated and consumed in the world due to its multiple health benefits. It has been used as an important herbal medicine in traditional Chinese medicine and also as one of the most popular fruits. There are various kinds of bioactive compounds in F. margarita, such as polysaccharides, limonoids, essential oils, flavonoids, phenolic acids, vitamins, dietary fiber, etc. In addition, many studies have reported that these bioactive compounds can be used as antioxidant, antimicrobial, hypolipidemic, drosophila lure components in functional foods, pharmaceuticals and daily chemical products due to their biological activities. This review focuses on the structural features and biological activities of polysaccharides, limonoids, essential oils and flavonoids and other bioactive substances from F. margarita and their potential applications in food, daily chemical and pharmaceutical industries.     

Selective Modification of Chitin and Chitosan: En Route to Tailored Oligosaccharides

Chitin and chitosan are attractive biopolymers with enormous structural possibilities for chemical modification, creating platforms for new chemical entities with a broad scope of applications, ranging from material science to medicine. During the last few years, incredible efforts have been dedicated to the regioselective modification of these biopolymers paving the way for improved properties and tailored activities. Herein, the most recent advances in chitin/chitosan regioselective modification, reaction conditions, selectivity, and the impact on its applications are highlighted. Moreover, the recent focus on chitooligosaccharides, their regioselective and chemoselective functionalization, as well as their role in biological studies, including molecular recognition with several biological targets are also covered.     

Chemical Physics in Living Cells-using Light to Visualize and Control Intracellular Signal Transduction?

Cells are crowded microenvironments filled with macromolecules undergoing constant physical and chemical interactions. The physicochemical makeup of the cells affects various cellular responses, determines cell-cell interactions and influences cell decisions. Chemical and physical properties differ between cells and within cells. Moreover, these properties are subject to dynamic changes in response to environmental signals, which often demand adjustments in the chemical or physical states of intracellular molecules. Indeed, cellular responses such as gene expression rely on the faithful relay of information from the outside to the inside of the cell, a process termed signal transduction. The signal often traverses a complex path across subcellular spaces with variable physical chemistry, sometimes even influencing it. Understanding the molecular states of such signaling molecules and their intracellular environments is vital to our understanding of the cell. Exploring such intricate spaces is possible today largely because of experimental and theoretical tools. Here, we focus on one tool that is commonly used in chemical physics studies-light. We summarize recent work which uses light to both visualize the cellular environment and also control intracellular processes along the axis of signal transduction. We highlight recent accomplishments in optical microscopy and optogenetics, an emerging experimental strategy which utilizes light to control the molecular processes in live cells. We believe that optogenetics lends unprecedented spatiotemporal precision to the manipulation of physicochemical properties in biological contexts. We hope to use this work to demonstrate new opportunities for chemical physicists who are interested in pursuing biological and biomedical questions.     

Order and chaos in chemistry and biology

Summary New physical techniques in combination with suitable computer and mathematical methodology allow to penetrate highly complex, non-linear, classical and dissipative processes and to unravel the dynamic nature of time and space structures in many areas of science. The new dimensions, the fractals, the multi-dimensional displays of dynamic states readily yield a quantification of such processes not only in the range of elementary particle physics, but also in the field of chemistry, of biochemistry, of medicine and biology, ecology, population dynamics, atmosphere chemistry and weather research. Ever since an analysis and quantification of chaotic states on mathematical grounds became possible and since the universal character of chaotic dynamics was recognized, a new area opened up for many scientists. Some properties of deterministic chaos and order will be exemplified on the basis of the analysis of chemical and biological systems. Furthermore, the manifold of nonlinear systems will be displayed as analyzed by logistic equations. In addition, some fundamental features of chaotic regimes are discussed.     

Rho-kinase inhibitors from adlay seeds

Rho-kinase enzymes are one of the most important targets recently identified in our bodies. Several lines of evidence indicate that these enzymes are involved in many diseases and cellular disorders. ROCK inhibitors may have clinical applications for cancer, hypertension, glaucoma, etc. Our study aims to identify the possible involvement of Rho-kinase inhibition to the multiple biological activities of adlay seeds and provide a rationale for their folkloric medicines. Hence, we evaluated Rho-kinase I and II inhibitory activity of the ethanol extract and 28 compounds derived from the seeds. A molecular docking assay was designed to estimate the binding affinity of the tested compounds with the target enzymes. The results of our study suggest a possible involvement of Rho-kinase inhibition to the multiple biological activities of the seeds. Furthermore, the results obtained with the tested compounds revealed some interesting skeletons as a scaffold for design and development of natural Rho-kinase inhibitors.     

金属四苯基卟啉在氧化银和银胶体上的表面增强拉曼光谱研究(英文)

研究了四苯基卟啉金属配合物 (MTPP ;M =Ag ,Cu ,Pd ,Mg)和游离碱 (H2 TPP)在氧化银和银胶体中的表面增强拉曼光谱 (SERS) .在Ag2 O胶体中MTPP和H2 TPP的SERS谱与其普通拉曼谱明显不同 ,可知吸附分子在Ag2 O胶粒表面发生反应所引起 ,况且产物于 4 6 0nm附近有一强烈吸收 ,可知它含有共扼双吡咯发色团 .在OH- 修饰的银胶上也观察到类似的光谱变化 .     

Total Synthesis of Lactacystin and Salinosporamide A

Lactacystin and salinosporamide A are fascinating molecules with regard to both their chemical structures and biological activities. These naturally occurring compounds are potent and selective proteasome inhibitors. The molecular structures are characterized by their densely functionalized γ‐lactam cores. The structure and biological properties of these two compounds are attracting the attention of many chemists as challenging synthetic targets. We discuss their synthetic strategies in this review.     

Are diamond nanoparticles cytotoxic?

Finely divided carbon particles, including charcoal, lampblack, and diamond particles, have been used for ornamental and official tattoos since ancient times. With the recent development in nanoscience and nanotechnology, carbon-based nanomaterials (e.g., fullerenes, nanotubes, nanodiamonds) attract a great deal of interest. Owing to their low chemical reactivity and unique physical properties, nanodiamonds could be useful in a variety of biological applications such as carriers for drugs, genes, or proteins; novel imaging techniques; coatings for implantable materials; and biosensors and biomedical nanorobots. Therefore, it is essential to ascertain the possible hazards of nanodiamonds to humans and other biological systems. We have, for the first time, assessed the cytotoxicity of nanodiamonds ranging in size from 2 to 10 nm. Assays of cell viability such as mitochondrial function (MTT) and luminescent ATP production showed that nanodiamonds were not toxic to a variety of cell types. Furthermore, nanodiamonds did not produce significant reactive oxygen species. Cells can grow on nanodiamond-coated substrates without morphological changes compared to controls. These results suggest that nanodiamonds could be ideal for many biological applications in a diverse range of cell types.     

The Importance of Chemistry in the Development of High-Performance Ceramics

Due to their mechanical, thermal and chemical stability, high-performance ceramics have a range of properties which makes it possible in many fields to go beyond the limits of use of the various classes of materials nowadays available. In spite of this favorable starting situation, the worldwide endeavors to introduce this new group of materials have suffered some setbacks in both conventional applications and in new technologies. The ultimate reason is that these materials are very brittle. After the introduction of fracture mechanics, designers in many fields have learned how to handle brittle materials and how to exploit the potential of their properties in components subject to extreme loadings. Materials scientists have also been very successful in developing ceramics with high strength and fracture toughness characteristics. Nevertheless, the field of use has hitherto been restricted, since, in many cases, the reliability of the components is inadequate. Small and very small defects, such as micropores and cracks, as well as any other chemical and physical inhomogeneity in the structure can cause catastrophic failure of the components due to the high brittleness. Since, on the one hand, these defects are as a rule caused by inadequate control of the process sequences and, on the other, the production processes comprise a large number of chemical process steps, it is to be hoped that consistent application of the way of thinking and procedures of a chemist will make an important contribution in overcoming these difficulties.     

Diversity in Chemical Structures and Biological Properties of Plant Alkaloids

Phytochemicals belonging to the group of alkaloids are signature specialized metabolites endowed with countless biological activities. Plants are armored with these naturally produced nitrogenous compounds to combat numerous challenging environmental stress conditions. Traditional and modern healthcare systems have harnessed the potential of these organic compounds for the treatment of many ailments. Various chemical entities (functional groups) attached to the central moiety are responsible for their diverse range of biological properties. The development of the characterization of these plant metabolites and the enzymes involved in their biosynthesis is of an utmost priority to deliver enhanced advantages in terms of biological properties and productivity. Further, the incorporation of whole/partial metabolic pathways in the heterologous system and/or the overexpression of biosynthetic steps in homologous systems have both become alternative and lucrative methods over chemical synthesis in recent times. Moreover, in-depth research on alkaloid biosynthetic pathways has revealed numerous chemical modifications that occur during alkaloidal conversions. These chemical reactions involve glycosylation, acylation, reduction, oxidation, and methylation steps, and they are usually responsible for conferring the biological activities possessed by alkaloids. In this review, we aim to discuss the alkaloidal group of plant specialized metabolites and their brief classification covering major categories. We also emphasize the diversity in the basic structures of plant alkaloids arising through enzymatically catalyzed structural modifications in certain plant species, as well as their emerging diverse biological activities. The role of alkaloids in plant defense and their mechanisms of action are also briefly discussed. Moreover, the commercial utilization of plant alkaloids in the marketplace displaying various applications has been enumerated.     

Functional Zwitterionic Polymers on Surface: Structures and Applications

Zwitterionic polymers are important in a wide range of industrial, biological and medical fields. Their chemical structures include an equal amount of anion and cation groups, and such structures give rise to many unique functionalities, such as temperature response, anti‐polyelectrolyte effect, and strong hydration properties. In this review, we focus on the structures and applications of functional zwitterionic polymers on surfaces. We review three areas of applications according to the architecture of the polymeric systems: surface coating, complex solutions, and hydrogel. We review the simulation and theory work and highlight some outlooks for further development.     

Functionalized gold nanoparticle supported sensory mechanisms applied in detection of chemical and biological threat agents: A review

There is a great necessity for development of novel sensory concepts supportive of smart sensing capabilities in defense and homeland security applications for detection of chemical and biological threat agents. A smart sensor is a detection device that can exhibit important features such as speed, sensitivity, selectivity, portability, and more importantly, simplicity in identifying a target analyte. Emerging nanomaterial based sensors, particularly those developed by utilizing functionalized gold nanoparticles (GNPs) as a sensing component potentially offer many desirable features needed for threat agent detection. The sensitiveness of physical properties expressed by GNPs, e.g. color, surface plasmon resonance, electrical conductivity and binding affinity are significantly enhanced when they are subjected to functionalization with an appropriate metal, organic or biomolecular functional groups. This sensitive nature of functionalized GNPs can be potentially exploited in the design of threat agent detection devices with smart sensing capabilities. In the presence of a target analyte (i.e., a chemical or biological threat agent) a change proportional to concentration of the analyte is observed, which can be measured either by colorimetric, fluorimetric, electrochemical or spectroscopic means. This article provides a review of how functionally modified gold colloids are applied in the detection of a broad range of threat agents, including radioactive substances, explosive compounds, chemical warfare agents, biotoxins, and biothreat pathogens through any of the four sensory means mentioned previously.     

Self-assembly of various guest substrates in natural cellulose substances to functional nanostructured materials

Biological organisms are produced from self-assembly of highly ordered functional units and are inherently complex and hierarchical, possessing macro-to-nanoscale features. It is a facile, low-cost and environmentally benign short-cut to artificial functional materials with unique multilevel structures and morphologies employing biological substances as platform for the self-assembly of various guest substrates. This review summarizes the recent advances in the fabrication of nanostructured materials with designed properties and functionalities by means of self-assembly of different guest substrates (such as metal oxide thin films, small molecules, polymers, biomacromolecules, nanoparticles, carbon nanotubes and colloidal spheres) on the surfaces of cellulose nanofibers of bulk natural cellulose substances. The combination of the specific chemical properties of the guest substrates and the unique physical features of the natural cellulose substances sheds new light on the design and syntheses of new functional nanomaterials.