Showing papers in "Current Organic Chemistry in 2014"
98 citations
TL;DR: Chalcones belong to the flavonoid family and constitute one of the major classes of naturally occurring oxygen heterocyclic compounds, leading to the synthesis of promising bioactive compounds as mentioned in this paper.
Abstract: Chalcones belong to the flavonoid family which constitutes one of the major classes of naturally occurring oxygen heterocyclic compounds. The , -unsaturated carbonyl system of chalcones possesses two electrophilic reactive centers allowing them to participate in addition reactions via attack to the carbonyl group (1,2-addition) or involving the -carbon (1,4-conjugate addition), leading to the synthesis of promising bioactive heterocyclic compounds. The purpose of this review is to present a systematic survey of the most recent literature that uses chalcones in the synthesis of biologically active 5and 6-membered nitrogen heterocycles such as pyrroles, indoles, isoxazoles, imidazoles, pyrazoles, indazoles, triazoles, tetrazoles, pyridines and pyrimidines. Efficiency, easy-to-handle and cheap reagents, alternative heating conditions and greener protocols will be highlighted. In this review we will cover the literature since the beginning of the 21 century in more than 400 publications.
77 citations
67 citations
TL;DR: In this article, a review systematically summarized the recent advances in the syntheses of 1,2,4-triazole derivatives, including cyclizations to form triazole ring; transformations of heterocyclic compounds to construct triazola ring; Substitutions on 1 2 4, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 28
Abstract: Heterocyclic 1,2,4-triazole derivatives possess unusually spacious potentiality as medicinal agents, agricultural chemicals, functional materials, ionic liquids, supramolecular catalysts as well as artificial enzymes and receptors for supramolecular recognition and biomimetic catalysis, and their various researches and developments have been being a quite rapidly developing and active highlight topic with an infinite space. Numerous efforts have been directed toward various types of possible applications of 1,2,4-triazole-based compounds and a lot of important progress has been made, especially their preparations have attracted increasing attention. This review systematically summarized the recent advances in the syntheses of 1,2,4-triazole derivatives, including: (1) Cyclizations to form triazole ring; (2) Transformations of heterocyclic compounds to construct triazole ring; (3) Substitutions on 1,2,4-triazole ring; (4) Structural modifications in side chains of 1,2,4-triazole ring. It was hoped that this review would be helpful for the design and development of highly efficient preparation of 1,2,4-triazole derivatives with various sorts and varieties of extensively potential applications in medicine, agriculture, chemistry, materials, supramolecular sciences and so on.
66 citations
62 citations
TL;DR: A survey on the recent developments of the standard cut method is given in this paper, where a number of extensions of the cut method have been proposed, such as the generalized terminal Wiener index, the Gutman index, and the edge-Wiener index.
Abstract: The cut method is a powerful tool for the investigation of distance-based (and some other) molecular structure-descriptors. In this paper a survey on the recent developments of the method is given. The instances of the standard cut method for the Wiener index, the Szeged index, the PI index, the generalized terminal Wiener index, the Gutman index, the edge-Wiener index, and the edge-Szeged index are described, where a standard cut method is a method that applies to partial cubes. It is pointed out that the standard cut method was recently independently discovered a couple of times. Numerous proper extensions of the standard cut method are presented. The method extends to `1-graphs, graphs with a non-trivial canonical metric representation, graphs with transitive relation Θ, and partial Hamming graphs. The instances of these extended cut methods include the Wiener index, the degree distance, distance moments, and the colored Wiener index.
59 citations
TL;DR: The formation of quinone methides (QMs) from either direct 2-electron oxidation of 2- or 4-alkylphenols, isomerization of o-quinones, or elimination of a good leaving group could explain the cytotoxic/cytoprotective effects of several drugs, natural products, as well as endogenous compounds.
Abstract: The formation of quinone methides (QMs) from either direct 2-electron oxidation of 2- or 4-alkylphenols, isomerization of o-quinones, or elimination of a good leaving group could explain the cytotoxic/cytoprotective effects of several drugs, natural products, as well as endogenous compounds. For example, the antiretroviral drug nevirapine and the antidiabetic agent troglitazone both induce idiosyncratic hepatotoxicity through mechanisms involving quinone methide formation. The anesthetic phencyclidine induces psychological side effects potentially through quinone methide mediated covalent modification of crucial macromolecules in the brain. Selective estrogen receptor modulators (SERMs) such as tamoxifen, toremifene, and raloxifene are metabolized to quinone methides which could potentially contribute to endometrial carcinogenic properties and/or induce detoxification enzymes and enhance the chemopreventive effects of these SERMs. Endogenous estrogens and/or estrogens present in estrogen replacement formulations are also metabolized to catechols and further oxidized to o-quinones which can isomerize to quinone methides. Both estrogen quinoids could cause DNA damage which could enhance hormone dependent cancer risk. Natural products such as the food and flavor agent eugenol can be directly oxidized to a quinone methide which may explain the toxic effects of this natural compound. Oral toxicities associated with chewing areca quid could be the result of exposure to hydroxychavicol through initial oxidation to an o-quinone which isomerizes to a p-quinone methide. Similar o-quinone to p-quinone methide isomerization reactions have been reported for the ubiquitous flavonoid quercetin which needs to be taken into consideration when evaluating risk-benefit assessments of these natural products. The resulting reaction of these quinone methides with proteins, DNA, and/or resulting modulation of gene expression may explain the toxic and/or beneficial effects of the parent compounds.
57 citations
TL;DR: In this article, the authors present the level of knowledge accumulated on the antibacterial and antifungal activity of ZnO nanoparticles and present the potential applications for agents that control the spread of bacterial strains.
Abstract: Metal oxide nanoparticles represent a new class of important materials that are increasingly being developed for use in re- search and health-related applications. Although the in vitro antibacterial activity of zinc oxides and some other zinc compounds has been known for quite some time, only in the last few years nanoparticles of ZnO have been investigated for their antibacterial activity, the knowledge about it remaining deficient. The antimicrobial activity of ZnO nanoparticles is strongly influenced by some factors such as size and the presence of light. The potential applications include, but are not limited to, topic drugs, cosmetics or component for agents that control the spread of bacterial strains (antibacterial paint in hospitals, antibacterial coatings for fabrics, antibacterial packaging for food, etc). The current review aims to present the level of knowledge accumulated on the antibacterial and antifungal activity of ZnO.
56 citations
TL;DR: In this paper, a review of studies on the occurrence of several emerging environmental contaminants, namely bisphenol A (BPA), TBBPA, phthalates, parabens, and other environmental phenolic compounds in indoor dust from various countries, were reviewed.
Abstract: Dust from indoor environments can contain significant amounts environmental contaminants and is an important source of human exposure to several toxicants. In this article, studies on the occurrence of several emerging environmental contaminants, namely bisphenol A (BPA), tetrabromobisphenol A (TBBPA), phthalates, parabens, and other environmental phenolic compounds in indoor dust from various countries, were reviewed. Issues associated with sampling of dust and the uncertainties introduced in the analytical proce- dures were also summarized. Finally, exposure to environmental phenolic compounds through dust ingestion was evaluated, and the contribution of indoor dust to the total daily exposure of toxicants was estimated. Overall, the reported concentrations of target chemicals in dust were found, in decreasing order, as phthalates (overall mean: 949 ± 669 μg/g, range: 0.9-10,900 μg/g) >>> nonylphenol (8.9 ± 6.8 μg/g, 2.6-29.2 μg/g) > BPA (3.6 ± 4.5 μg/g, 0.35-16.6 μg/g) > � parabens (1.53 ± 0.52 μg/g, 0.03-125 μg/g) > pentachlorophenol (1.39 ± 2.31 μg/g, 0.050- 5.76 μg/g) > triclosan (0.65 ± 0.23 μg/g, 0.38-0.93 μg/g) > TBBPA (0.18 ± 0.14 μg/g, 0.049-0.505 μg/g). Despite the elevated levels of the target phenolic compounds reported in indoor dust, exposure of humans through dust ingestion was minor. Never- theless, dust can be a significant source of exposure to phenolic compounds for infants and toddlers. Elevated levels of phenolic com- pounds were found in dust collected from certain microenvironments such as offices and laboratories.
50 citations
48 citations
TL;DR: This review provides a comprehensive overview of the different hybrid organic-inorganic scaffolding biomaterials developed so far for regenerative therapies, especially in bone and looks at the potential for research into hybrid materials for other, softer tissues, which is still at an initial stage, but with very promising results.
Abstract: The introduction of hybrid materials in regenerative medicine has solved some problems related to the mechanical and bioactive properties of biomaterials. Calcium phosphates and their derivatives have provided the basis for inorganic components, thanks to their good bioactivity, especially in bone regeneration. When mixed with biodegradable polymers, the result is a synergic association that mimics the composition of many tissues of the human body and, additionally, exhibits suitable mechanical properties. Together with the development of nanotechnology and new synthesis methods, hybrids offer a promising option for the development of a third or fourth generation of smart biomaterials and scaffolds to guide the regeneration of natural tissues, with an optimum efficiency/cost ratio. Their potential bioactivity, as well as other valuable features of hybrids, open promising new pathways for their use in bone regeneration and other tissue repair therapies. This review provides a comprehensive overview of the different hybrid organic-inorganic scaffolding biomaterials developed so far for regenerative therapies, especially in bone. It also looks at the potential for research into hybrid materials for other, softer tissues, which is still at an initial stage, but with very promising results.
TL;DR: This critical review features different photochemical reactions giving QMs that are applicable in biology and medicine.
Abstract: Quinone methides (QMs) are important intermediates in chemistry and biochemistry of phenols that are characterized by wide biological activity. Some classes of anticancer antibiotics exhibit their effect due to methabolic formation of QMs that alkylate DNA. Photochemical reactions provide mild and easy approach to QMs. Photoreactions that give QMs include cleavage of oxa-heterocycles, dehydrohalogenation, dehydration, deammination, excited state intramolecular proton transfer (ESIPT) and tautomerizations of phenols. This critical review (137 references) features different photochemical reactions giving QMs that are applicable in biology and medicine.
TL;DR: This review will focus on chitin polysaccharide, which is extracted according to industrial processing from exoskeleton of several marine crustaceans, and highlight the chemical modifications involving the listed marinepolysaccharides of interest.
Abstract: Polysaccharides are among the most abundant macromolecules on Earth. These polymers are easily obtained from various marine resources such as algae, microorganisms and crustacean shells. The structure of these natural carbohydrates is innovative and quite complex. Marine biopolymers represent key scaffolds toward large challenging fields, such as biomedical applications (glycosaminoglycans, regenerative medicine and drug delivery) and tailored biomaterials. Chemical modifications can be applied to modify their final properties in a specific purpose. New functional glycans are achievable and represent a real potential with their intrinsic biocompatibility and biodegradability. Hydroxyl groups are ubiquitous in polysaccharides structure and involved in most of the chemical modifications. The most useful functionalities are ester, ether, amide, amine and alkyl groups. The starting materials could be a natural or depolymerized polymers and the reaction considered with a regioselective point of view. In this review, we will focus on chitin polysaccharide, which is extracted according to industrial processing from exoskeleton of several marine crustaceans. A subsequent deacylation provides chitosan. This marine polysaccharide is very similar to cellulose, a widespread fiber plant organic polymer, except for an amine group on the C2 position instead of a hydroxyl group. Furthermore, seaweeds provide the most abundant sources of polysaccharides: alginates, agar/agarose, carrageenans and fuco dans. In order to improve the original physicochemical and biochemical properties, we will highlight the chemical modifications involving the listed marine polysaccharides of interest.
TL;DR: This review highlights the recent advances in the development of AIE fluorescent probes that are classified into various categories, including tetraphenylethenes, siloles, 9,10-distyrylanthracene, cyanostilbene and systems with extended � -conju- gations to those even without typical AIE chromophores.
Abstract: Compared with the conventional luminescent molecules, whose fluorescence is quenched once they aggregate, molecules with aggregation-induced emission (AIE) properties exhibit significantly enhanced emission in solid state or aggregates due to their unique molecular structures and stacking modes, showing potential applications in optoelectronic devices, biochemical sensors and bioimaging. Especially, AIE fluorophores recently have drawn much attention as an emerging sensory material. Taking advantage of AIE effects, fluorescence signals can be boosted by AIE dyes in presence of analytes, which offers a promising platform for sensor with intense fluo- rescence signal. In this review, we highlight the recent advances in the development of AIE fluorescent probes that are classified into various categories, including tetraphenylethenes, siloles, 9,10-distyrylanthracene, cyanostilbene and systems with extended � -conju- gations to those even without typical AIE chromophores. The fluorescent behaviors of these probes toward different analyte are discussed.