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Marine-inspired phenolic compounds that exhibit underwater adhesion are used as biomedical adhesives under wet conditions. While these applications mainly use catechol and pyrogallol moieties that contain different numbers of hydroxyl groups on their benzene rings, how this difference affects adhesion and cohesion is not well understood. Herein, the chitosan backbone is functionalized with catechol and pyrogallol at similar modification rates (to give chitosan-catechol (CS-CA) and chitosan-pyrogallol (CS-GA), respectively) and their interaction energies are compared by using a surface forces apparatus (SFA). The phenolic moieties decrease the rigidity of the chitosan chain and increase solubility; consequently, CS-CA and CS-GA are more cohesive and adhesive than chitosan at pH 7.4. Moreover, the additional hydroxyl group of GA provides a further interacting chance; hence, CS-GA is more cohesive and adhesive than CS-CA. This study provides in-depth insight into interactions involving chitosan derivatives bearing introduced phenolic moieties that will help to develop biomedical adhesives., (© 2022 Wiley-VCH GmbH.)

Toll-like receptors (TLRs) build the first barrier in the innate immune response and therefore represent promising targets for the modulation of inflammatory processes. Recently, the pyrogallol-containing TLR2 antagonists CU-CPT22 and MMG-11 were reported; however, their 1,2,3-triphenol motif renders them highly susceptible to oxidation and excludes them from use in extended experiments under aerobic conditions. Therefore, we have developed a set of novel TLR2 antagonists (1-9) based on the systematic variation of substructures, linker elements, and the hydrogen-bonding pattern of the pyrogallol precursors by using chemically robust building blocks. The novel series of chemically stable and synthetically accessible TLR2 antagonists (1-9) was pharmacologically characterized, and the potential binding modes of the active compounds were evaluated structurally. Our results provide new insights into structure-activity relationships and allow rationalization of structural binding characteristics. Moreover, they support the hypothesis that this class of TLR ligands bind solely to TLR2 and do not directly interact with TLR1 or TLR6 of the functional heterodimer. The most active compound from this series (6), is chemically stable, nontoxic, TLR2-selective, and shows a similar activity with regard to the pyrogallol starting points, thus indicating the variability of the hydrogen bonding pattern., (© 2020 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.)

Cell nanoencapsulation, generating cell-in-shell structures ("artificial spores"), provides a chemical toolbox for controlling the cellular behaviors and functional characteristics of individual cells. Among the shell materials studied so far, naturally occurring polyphenolic compounds, including polydopamine and tannic acid, have intensively been employed in cell-surface engineering, because their material-independent coating property eliminates an extra priming step for inducing subsequent shell formation. Albeit successful in generating cell-in-shell structures, the coating of polyphenolic compounds generally requires alkaline conditions and/or high salt conditions, which are not compatible with certain cell types. In this work, we demonstrate that the nanocoating of individual cells with a plant-derived phenolic compound, pyrogallol (1,2,3-trihydroxybenzene), occurs at mildly alkaline pH of 7.8 in an isotonic buffer. Three different cell types (anucleate, microbial, and mammalian cells) are coated with pyrogallol without noticeable decrease in cell viability. The protocol developed in this work could be applied to other polyphenolic compounds, and, considering the many polyphenols identified as a coating material, provides an advanced chemical tool in cell-surface engineering., (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Numerous technologies have been used to reclaim valuable chemicals from bio-oil. In this study, a combination of the basification-acidification process and column chromatography was employed for the separation of high-purity syringol and acetosyringone from rice straw-derived bio-oil. The optimal conditions for the basification-acidification process and the possible precipitation mechanism of the basification were explored. The results showed the following as the optimal conditions for the basification process: mass ratio of calcium hydroxide (Ca(OH) 2 ) to bio-oil, 2.0; reaction temperature, 70°C; and reaction time, 30 min. The results also showed that 1.6 mol of hydrochloric acid (HCl) per gram of bio-oil was optimal for the acidification. The precipitation was found to proceed via a possible mechanism involving the reaction of the phenolic compounds in the bio-oil with Ca(OH) 2 to produce a precipitate. After further separation by column chromatography, purities of 91.4 and 96.2% (from gas chromatography-mass spectrometry) were obtained for syringol and acetosyringone, respectively. Their recoveries for the whole process were 73.0 and 39.3%, respectively., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A series of functional polycarbonates, poly((isopropylidene glyceryl glycidyl ether)-co-(glycidyl methyl ether) carbonate) (P((IGG-co-GME) C)) random copolymers with different fractions of 1,2-isopropylidene glyceryl glycidyl ether (IGG) units, is synthesized. After acidic hydrolysis of the acetal protecting groups, a new type of functional polycarbonate prepared directly from CO(2) and glycerol is obtained, namely poly((glyceryl glycerol)-co-(glycidyl methyl ether) carbonate) (P((GG-co-GME) C)). All hydroxyl functional samples exhibit monomodal molecular weight distributions with PDIs between 2.5 and 3.3 and M(n) between 12 000 and 25 000 g mol(-1) . Thermal properties reflect the amorphous structure of the polymers. The materials are stable in bulk and solution., (Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The behavior of pyrogallol[4]arenes (Pgs) substituted with normal and branched alkyl side chains at the air-water interface was examined on a Langmuir trough. The amphiphilic systems studied form stable monolayers when the straight chains are as short as n-propyl. Remarkably, n-propylpyrogallol[4]arene shows a behavior at the air-water interface that is indistinguishable from that of pyrogallolarenes bearing n-hexyl, n-nonyl, and n-dodecyl side chains. There is no report of amphiphilic side-chain-length dependence or Langmuir trough behavior for families of branched alkyl chain calixarenes or resorcinarenes. In the Pg family reported here, Pgs with straight chains (except for methyl and ethyl) behave very similarly to each other and very differently from symmetrical branched chain analogues having the same total number of carbon atoms. For example, the shortest possible branched side chain of a Pg, isopropyl-Pg, forms stable monolayers by a unique molecular subduction mechanism. Isopropyl-Pg (dimethylmethyl side chain, iPrPg) and 3-pentyl-Pg (diethylmethyl side chain, 3-pentylPg) both show high levels of organization, albeit by quite different mechanisms, at the air-water interface. Both iPrPg and 3-pentylPg differ in behavior from 4-heptylPg. Brewster angle microscopy revealed differences in organization of the Pgs that supports the mechanistic suggestions offered herein., (Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

3',4'-Dihydroxyflavonol (DiOHF) is a cardioprotective flavonol that can decrease ischaemia/reperfusion injury in the heart. DiOHF exhibits antioxidant and vasorelaxant properties that are thought to underlie its cardioprotective activity. A major limitation to its use for the treatment or prevention of cardiovascular disease is its poor water solubility, preventing intravenous administration at the required dosage. In this study, three novel flavonols were synthesised that bear an ionisable succinamic acid substituent at the 6-position of the A ring with zero, one, or two hydroxy groups on the B ring. The ionised compounds possess improved aqueous solubility, dissolving at concentrations up to 10(-1) m, whereas DiOHF is insoluble in water (<10(-7) m). Pharmacological analysis revealed that the DiOHF-6-succinamic acid derivative was the best antioxidant, possessing activity similar to DiOHF, whereas vasorelaxant activity was attenuated. This compound was able to effectively scavenge superoxide from the autoxidation of pyrogallol, preventing oxidant-induced endothelial dysfunction. DiOHF-6-succinamic acid represents the first antioxidant flavonol that lacks vasorelaxant activity and in the future will enable studies to cast light on the specific biological activity required for cardioprotection.

Peroxidase activity of a complex of water-soluble cationic metalloporphyrin with anti-cationic porphyrin antibody is reported. Antibody 12E11G, which was prepared by immunization with a conjugate of 5-(4-carboxyphenyl)-10,15,20-tris(4-methylpyridyl)porphine iodide (3MPy1C), bound to tetramethylpyridylporphyrin iron complex (FeIII-TMPyP) with the dissociation constant of 2.6 x 10(-7) M. The complex of antibody 12E11G with FeIII-TMPyP catalyzed oxidation of pyrogallol, catechol, and guaiacol. A Lineweaver-Burk plot for the oxidation of pyrogallol catalyzed by the FeIII-TMPyP-antibody complex showed Km=8.6 mM and kcat=680 min(-1). Under the same conditions, Km and kcat for horseradish peroxidase (HRP) were 0.8 mM and 1750 min(-1), respectively. Although the binding interaction of the antibody to the substrates was one order lower than that of native HRP, the peroxidase activity of this system was in the same order of magnitude as that of HRP.

Certain metal complexes selectively interact with proteins immobilized on solid-phase membrane supports to form brightly colored products. The metal chelates form protein-dye complexes in the presence of metal ions at acidic pH but are eluted from the proteins by immersing membranes in a solution of basic pH that contains other chelating agents. The reversible nature of the protein staining procedure allows for subsequent biochemical analyses, such as immunoblotting, N-terminal and internal protein sequencing. Among the metal complexes evaluated to date, the triazine dye-ferrous complexes (ferene S, ferrozine) and the ferrocyanide-ferric complexes provide the most sensitive detection of proteins immobilized on membranes. While the pyrogallol red-molybdate complex is commonly used in solution-based total protein assays, its utility as a reversible stain for proteins immobilized on membranes has not been reported. Pyrogallol red-molybdate complexes readily stain proteins on nitrocellulose and polyvinyl difluoride membranes with similar sensitivity as ferrozine-ferrous complexes. Analysis of charge-fractionated carrier ampholytes and synthetic polymers of different L-amino acids indicate that binding is prominently via protonated alpha and epsilon-amino side chains. Carbamylation of amino groups in bovine serum albumin substantially diminishes pyrogallol red-molybdate binding to the protein. The stain is reversible, resistant to chemical interference, and compatible with immunoblotting.

The pyrogallol red protein assay (Clinical Chemistry 1986, 32, 1551-1554) is based upon formation of a blue protein-dye complex in the presence of molybdate under acidic conditions. However, centrifugation of the assay mixture results in loss of color yield and precipitation of the protein-dye complex which can be recovered and resolubilized to achieve protein concentration prior to sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The method has been evaluated relative to trichloroacetic acid (TCA) precipitation for recovery and electrophoresis of commercial protein and peptide molecular weight markers. Precipitation with pyrogallol red-molybdate (PRM) gives better and more uniform recovery of both proteins and peptides as compared to TCA. The lower limit of PRM precipitation is similar to TCA and corresponds to 1 microgram protein per mL assay mixture. This is equivalent to 100 microL of 10 micrograms/mL protein using the standard protein assay or 1 microgram/mL protein using a modified assay incorporating a fivefold concentrate of the dye reagent. Application of the method is demonstrated by concentration of urinary proteins. The method is simple and economic and useful for conserving trace amounts of precious sample as it allows recovery of protein for electrophoresis following protein assay.