A biomimetic route to the peptide alkaloid anachelin.
TL;DR: Experiments with a model substrate indicate that it is likely that a catechol oxidase-type enzyme is involved in the biosynthesis of the anachelin chromophore.
Abstract: A postulated biogenesis forms the basis for a synthetic route to the natural product anachelin H. Key steps include a tellurium-mediated, oxidative aza annulation and a Claisen condensation under mild conditions. Experiments with a model substrate indicate that it is likely that a catechol oxidase-type enzyme is involved in the biosynthesis of the anachelin chromophore.
Citations
More filters
TL;DR: The state-of-the-art research in the area is described: the design and synthesis of catecholic molecules, their adsorption mechanisms and the stability of assemblies in solution, and their applications etc.
Abstract: The attachment strategy based on catecholic chemistry has been arousing renewed interest since the work on polymerized catecholic amine (polydopamine) (Messersmith et al., Science, 2007, 318, 426) was published. Catechols and their derived compounds can self-assemble on various inorganic and organic materials, including noble metals, metals, metal oxides, mica, silica, ceramics and even polymers. It opens a new route to the modification of various substrates and the preparation of functional composite materials by simple chemistry. However, there is still not a full review so far about the attachment chemistry despite the dramatically increasing number of publications. This critical review describes the state-of-the-art research in the area: the design and synthesis of catecholic molecules, their adsorption mechanisms and the stability of assemblies in solution, and their applications etc. Some perspectives on future development are raised (195 references).
1,039 citations
785 citations
TL;DR: It is shown that catechols can be found either as simple molecular systems, forming part of supramolacular structures, coordinated to different metal ions or as macromolecules mostly arising from polymerization mechanisms through covalent bonds.
Abstract: Catechols are found in nature taking part in a remarkably broad scope of biochemical processes and functions. Though not exclusively, such versatility may be traced back to several properties uniquely found together in the o-dihydroxyaryl chemical function; namely, its ability to establish reversible equilibria at moderate redox potentials and pHs and to irreversibly cross-link through complex oxidation mechanisms; its excellent chelating properties, greatly exemplified by, but by no means exclusive, to the binding of Fe(3+); and the diverse modes of interaction of the vicinal hydroxyl groups with all kinds of surfaces of remarkably different chemical and physical nature. Thanks to this diversity, catechols can be found either as simple molecular systems, forming part of supramolacular structures, coordinated to different metal ions or as macromolecules mostly arising from polymerization mechanisms through covalent bonds. Such versatility has allowed catechols to participate in several natural processes and functions that range from the adhesive properties of marine organisms to the storage of some transition metal ions. As a result of such an astonishing range of functionalities, catechol-based systems have in recent years been subject to intense research, aimed at mimicking these natural systems in order to develop new functional materials and coatings. A comprehensive review of these studies is discussed in this paper.
613 citations
TL;DR: It is concluded that optimum coating protocols for catechol-based polymer assembly at metal oxide interfaces have to take into account specific physicochemical properties of the polymer, anchor, and substrate.
Abstract: We have investigated Five different poly(ethylene glycol) (PEG, 5 kDa) catechol derivatives in terms of their spontaneous surface assembly from aqueous solution, adlayer stability, and resistance to nonspecific blood serum adsorption as a function of the type of catechol-based anchor, assembly conditions (temperature, pH), and type of substrate (SiO2, TiO2, Nb2O5), Variable-angle spectroscopic ellipsometry (VASE) was used for layer thickness evaluation, X-ray photoelectron spectroscopy (XPS) for layer composition, and ultraviolet-visible optical spectroscopy (UV-vis) for cloud point determination. Polymer surface coverage was influenced by the type of catechol anchor, type of the substrate, as well as pH and temperature (7) of the assembly solution. Furthermore, it was found to be highest for T close to the cloud point (T-CP) and pH of the assembly solution close to pK(a1) (dissociation constant of the first catechol hydroxy group) of the polymer and to the isoelectric point (1EP) of the substrate. T-CP turned out to depend on not only the ionic strength of the assembly solution, but also the type of catechol derivative and pH. PEG-coating dry thickness above 10 angstrom correlated with low serum adsorption. We therefore conclude that optimum coating protocols for catechol-based polymer assembly at metal oxide interfaces have to take into account specific physicochemical properties of the polymer, anchor, and substrate.
122 citations
TL;DR: Two new modified hexacyclopeptides, aerucyclamides A and B, were isolated from the toxic freshwater cyanobacterium Microcystis aeruginosa PCC 7806 and were found to be toxic to the freshwater crustacean Thamnocephalus platyurus.
Abstract: Two new modified hexacyclopeptides, aerucyclamides A and B, were isolated from the toxic freshwater cyanobacterium Microcystis aeruginosa PCC 7806. The constitution was assigned by spectroscopic methods, and the configuration determined by chemical degradation and analysis by Marfey’s method combined with chemical synthesis. Synthetic aerucyclamide B was obtained through oxidation of aerucyclamide A (MnO2, benzene). The aerucyclamides were found to be toxic to the freshwater crustacean Thamnocephalus platyurus, exhibiting LC50 values for congeners A and B of 30.5 and 33.8 μM, respectively.
113 citations