Occurrence, biological activities and synthesis of kaurane diterpenes and their glycosides

This paper presents a review on kaurane diterpenes and their glycoside derivatives, covering aspects of their occurrence, biological activities and the synthesis of these natural products and their analogues. First, it shows and classifies diterpenes, in accordance with the already established structural criteria in the literature. Then, kaurane diterpenes are presented, focusing on their chemical structures, occurrence in the plant kingdom and their main, recently described, biological activities. Moreover, the most significant works, published between 1964 and November 2006, which describe the total synthesis or structural transformations of some kaurane diterpenes, including either semisynthetic and/or microbiological methodologies, are consisely reviewed. At this point, some general considerations on glycosides are introduced, and kaurane glycosides are presented and discussed on the basis of their toxic importance and occurrence in the plant kingdom, having focused on related aspects of their biological activities and the relationships between these activities and the structural factors of their molecules. Finally, the principal methods of glycosidation by enzymatic and chemical processes are both presented, and a few papers on the synthesis of kaurane glycosides are succinctly discussed.     

Anthocyanins and their variation in red wines I. Monomeric anthocyanins and their color expression

Originating in the grapes, monomeric anthocyanins in young red wines contribute the majority of color and the supposed beneficial health effects related to their consumption, and as such they are recognized as one of the most important groups of phenolic metabolites in red wines. In recent years, our increasing knowledge of the chemical complexity of the monomeric anthocyanins, their stability, together with the phenomena such as self-association and copigmentation that can stabilize and enhance their color has helped to explain their color representation in red wine making and aging. A series of new enological practices were developed to improve the anthocyanin extraction, as well as their color expression and maintenance. This paper summarizes the most recent advances in the studies of the monomeric anthocyanins in red wines, emphasizing their origin, occurrence, color enhancing effects, their degradation and the effect of various enological practices on them.     

苯并咪唑及其衍生物合成与应用研究进展

苯并咪唑及其衍生物具有良好的生物活性, 而且是一种重要的药物中间体. 由于它们具有良好的生物活性和反应活性, 一直都是研究的热点. 从该类化合物的合成与应用两个方面综述了近年来该领域的重要研究成果.     

水滑石类催化剂催化制氢及生物炼制(英文)

近年来,水滑石由于其独特的性质受到越来越多的关注.作为非均相固体催化剂,水滑石及其衍生物具有优良的催化性能,因此得到了广泛研究和应用.本文简述了水滑石的几种合成方法,重点介绍了水滑石类催化剂在催化制氢和生物炼制方面的应用,并预测了水滑石类材料在新材料合成及环境友好催化体系中的应用前景.     

Carotenoids and their isomers: color pigments in fruits and vegetables

Fruits and vegetables are colorful pigment-containing food sources. Owing to their nutritional benefits and phytochemicals, they are considered as 'functional food ingredients'. Carotenoids are some of the most vital colored phytochemicals, occurring as all-trans and cis-isomers, and accounting for the brilliant colors of a variety of fruits and vegetables. Carotenoids extensively studied in this regard include β-carotene, lycopene, lutein and zeaxanthin. Coloration of fruits and vegetables depends on their growth maturity, concentration of carotenoid isomers, and food processing methods. This article focuses more on several carotenoids and their isomers present in different fruits and vegetables along with their concentrations. Carotenoids and their geometric isomers also play an important role in protecting cells from oxidation and cellular damages.     

常低温相变储热材料的研究和应用

将常低温相变储热材料分类,介绍了常低温相变储热材料的种类及各自特点,对固-液相变、固-固相变储热材料的性能、优缺点和应用进行了讨论,讲述了目前人们针对常低温相变储热材料的缺陷采取的解决方法。     

Semiconductor and Metallic Core–Shell Nanostructures: Synthesis and Applications in Solar Cells and Catalysis

Nano‐heterostructures have attracted great attention due to their extraordinary properties beyond those of their single‐component counterparts. This review focuses on a specific type of hybrid structures: core–shell structures. In particular, we present and discuss the recent wet‐chemical synthesis approaches for semiconductor and metallic core–shell nanostructures, and their relevant properties and potential applications in photovoltaics and catalysis, respectively.     

Structures and biological activity of cinnamoyl derivatives of coumarins and dehydroacetic acid and their boron difluoride complexes

Computer-assisted screening for Kohonen self-organizing maps in terms of the quantitative structure??activity relationship (QSAR) model revealed the high potential activity of cinnamoyl derivatives of coumarin and dehydroacetic acid and their boron difluoride complexes against a number of biological targets, including HIV-1 integrase. The pronounced inhibitory properties of dehydroacetic acid derivatives and their boron difluoride complexes against HIV-1 integrase were experimentally confirmed by in vitro testing of their antiviral activity with respect to HIV-infected cells. The data obtained suggests a correlation between the structure of the compounds studied and their biological activity.     

New developments in the extraction and determination of parabens in cosmetics and environmental samples. A review

Parabens are a family of synthetic esters of p-hydroxibenzoic acid widely used as preservatives in cosmetics and health-care products, among other daily-use commodities. Recently, their potential endocrine disrupting effects have raised concerns about their safety and their potential effects as emerging pollutants, leading to the regulation of the presence of parabens in commercial products by national and trans-national organizations. Also, this has led to an interest in developing sensible and reliable methods for their determination in environmental samples, cosmetics and health-care products.     

食物的色、香、味与食品添加剂

食品添加剂可以改善食品的品质,延长食品的保存期,增加食品的营养成分。本文介绍了生活中常见的食品添加剂：食品色素、食用香料、甜味剂、鲜味剂、防腐剂和抗氧化剂的性能、使用范围和化学结构。以便于在化学教学中开阔学生的知识视野,提高学生的学习兴趣,全面培养学生的科学素质。     

Antimicrobial Properties and Application of Polysaccharides and Their Derivatives

With the quick emergence of antibiotic resistance and multi-drug resistant microbes, more and more attention has been paid to the development of new antimicrobial agents that have potential to take the challenge. Polysaccharides, as one of the major classes of biopolymers,were explored for their antimicrobial properties and applications, owing to their easy accessibility, biocompatibility and easy modification.Polysaccharides and their derivatives have variable demonstrations and applications as antimicrobial agents and antimicrobial biomaterials. A variety of polysaccharides, such as chitosan, dextran, hyaluronic acid, cellulose, other plant/animal-derived polysaccharides and their derivatives have been explored for antimicrobial applications. We expect that this review can summarize the important progress of this field and inspire new concepts, which will contribute to the development of novel antimicrobial agents in combating antibiotic resistance and drug-resistant antimicrobial infections.     

Structure and dissociation of cyanogen halides BrCN and ICN

Structural properties and dissociation of cyanogen bromide BrCN, cyanogen iodide ICN, and their isomers have been studied in detail using ab initio MP2, CCSD, and CCSD(T) methods. After dissociation of BrCN and ICN, the fragmented atoms have been considered to be either in their ground state or in their valence excited states. The recent experimental value for the strength of the CN bond of CN radical has been compared with our value calculated from the dissociation of BrCN. Interesting results have been obtained when BrCN and ICN dissociated to atoms that are in their valence excited states. The structural properties of BrCN and ICN and dissociation energy of BrCN agree very well with the theoretical and experimental values wherever available. The dissociation pathways of ICN are first predicted. The isomerization energy of BrCN is compared with the existing theoretical result. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010     

Substituted Pyrazoles and Their Heteroannulated Analogs—Recent Syntheses and Biological Activities

Pyrazoles are considered privileged scaffolds in medicinal chemistry. Previous reviews have discussed the importance of pyrazoles and their biological activities; however, few have dealt with the chemistry and the biology of heteroannulated derivatives. Therefore, we focused our attention on recent topics, up until 2020, for the synthesis of pyrazoles, their heteroannulated derivatives, and their applications as biologically active moieties. Moreover, we focused on traditional procedures used in the synthesis of pyrazoles.     

Polymer Networks: A Challenge to Theorist and Technologist

Polymer networks challenge a theorist to develop methods of their generation, describe their topology, and understand critical phenomena (gelation) during their formation. They challenge a technologist because of their unique properties based on their large-scale three-dimensional connectivity and their easy transformation of relatively low-viscosity liquids into crosslinked solids. Polymer networks challenge both, in that they are structurally very complex for the technologist who needs the theorist for understanding and controlling their structure and properties. Also, the theorist is challenged by problems appearing in technology which may initiate a basic reconsideration of the theories' assumptions. In this contribution, methods for modeling polymer network structures and their recent applications to relatively complex systems of technological importance are briefly discussed.     

Bile Acids: Physiological Activity and Perspectives of Using in Clinical and Laboratory Diagnostics

Bile acids play a significant role in the digestion of nutrients. In addition, bile acids perform a signaling function through their blood-circulating fraction. They regulate the activity of nuclear and membrane receptors, located in many tissues. The gut microbiota is an important factor influencing the effects of bile acids via enzymatic modification. Depending on the rate of healthy and pathogenic microbiota, a number of bile acids may support lipid and glucose homeostasis as well as shift to more toxic compounds participating in many pathological conditions. Thus, bile acids can be possible biomarkers of human pathology. However, the chemical structure of bile acids is similar and their analysis requires sensitive and specific methods of analysis. In this review, we provide information on the chemical structure and the biosynthesis of bile acids, their regulation, and their physiological role. In addition, the review describes the involvement of bile acids in various diseases of the digestive system, the approaches and challenges in the analysis of bile acids, and the prospects of their use in omics technologies.     

Silicon Nanocrystals and Silicon‐Polymer Hybrids: Synthesis,Surface Engineering,and Applications

Silicon nanocrystals (Si‐NCs) are emerging as an attractive class of quantum dots owing to the natural abundance of silicon in the Earth's crust, their low toxicity compared to many Group II–VI and III–V based quantum dots, compatibility with the existing semiconductor industry infrastructure, and their unique optoelectronic properties. Despite these favorable qualities, Si‐NCs have not received the same attention as Group II–VI and III–V quantum dots, because of their lower emission quantum yields, difficulties associated with synthesizing monodisperse particles, and oxidative instability. Recent advancements indicate the surface chemistry of Si‐NCs plays a key role in determining many of their properties. This Review summarizes new reports related to engineering Si‐NC surfaces, synthesis of Si‐NC/polymer hybrids, and their applications in sensing, diodes, catalysis, and batteries.     

Allobetulin and its derivatives: synthesis and biological activity

This review covers the chemistry of allobetulin analogs, including their formation by rearrangement from betulin derivatives, their further derivatisation, their fusion with heterocyclic rings, and any further rearrangements of allobetulin compounds including ring opening, ring contraction and ring expansion reactions. In the last part, the most important biological activities of allobetulin derivatives are listed. One hundred and fifteen references are cited and the relevant literature is covered, starting in 1922 up to the end of 2010.     

Preparation and Properties,Reactions, and Applications of Radialenes

Radialenes are alicyclic compounds in which every ring atom is sp²-hybridized and carries an exocyclic C? C double bond. Because of their unusual topology and electronic structures these hydrocarbons have aroused the interest of both preparative chemists and theoreticians. Although considerable progress has been achieved recently, directed and efficient syntheses of these molecules remain a challenge. The study of their chemical behavior offers vast opportunities. Very recently materials scientists have become interested in these unusual compounds in their search for organic conductors and ferromagnets.     

Nanovesicles Loaded with Origanum onites and Satureja thymbra Essential Oils and Their Activity against Food-Borne Pathogens and Spoilage Microorganisms

Food poisoning is a common cause of illness and death in developing countries. Essential oils (EOs) could be effective and safe natural preservatives to prevent and control bacterial contamination of foods. However, their high sensitivity and strong flavor limit their application and biological effectiveness. The aim of this study was firstly the chemical analysis and the antimicrobial evaluation of the EOs of Origanum onites L. and Satureja thymbra L. obtained from Symi island (Greece), and, secondly, the formulation of propylene glycol-nanovesicles loaded with these EOs to improve their antimicrobial properties. The EOs were analyzed by GC-MS and their chemical contents are presented herein. Different nanovesicles were formulated with small average sizes, high homogeneity, and optimal ζ-potential. Microscopic observation confirmed their small and spherical shape. Antibacterial and antifungal activities of the formulated EOs were evaluated against food-borne pathogens and spoilage microorganisms compared to pure EOs. Propylene glycol-nanovesicles loaded with O. onites EO were found to be the most active formulation against all tested strains. Additionally, in vitro studies on the HaCaT cell line showed that nanovesicles encapsulated with EOs had no toxic effect. The present study revealed that both EOs can be used as alternative sanitizers and preservatives in the food industry, and that their formulation in nanovesicles can provide a suitable approach as food-grade delivery system.