Aromatic Functional Groups Research Articles

The Effect of the Monosubstituted Benzenes Functional Groups on the Inhibition of Methane Gas Biosynthesis

Aromatic compounds are inhibitors of methane biosynthesis in anaerobic treatment of solid wastes and industrial effluents. Anaerobic treatment of solid wastes and industrial effluents may be limited by the methanogenic bacteria inhibition exerted by these types of compounds, the production of biogas is not possible and the organic matter contained in the effluent is not reduced. These effluents poured in the nature can be the basis of the pollution. The objective of this study is to evaluate the effect of monosubstituted aromatic compounds functional groups on the methanogenic inhibition. The toxicity to acetoclastic methanogenic bacteria has performed in serum flasks, utilizing digested pig manure as inoculums, by measuring methane production. The nature of aromatic functional groups was observed to have a profound effect on the toxicity of the monosubstituted aromatics. Among the monosubstituted aromatic, the chlorobenzene was the most toxic with 50% of inhibition occurring at the concentration of 30.08 mg/l. In contrast, benzoic acid is the least inhibitory with IC50 of 2515.20 mg/l. The partition coefficient octanol/water (logPoct), an indicator of hydrophobicity, had a significant correlation with the methanogenic toxicity.

The Impact of the Bisubstituted Aromatics Functional Groups on the Inhibition of Methane Biosynthesis (Biogas)

Inhibitory compounds are often found to be the leading cause of anaerobic reactor upset and failure since they are present in substantial concentration in wastewaters and organic solid wastes. Among these inhibitory compounds, organic compounds are mentioned and more especially aromatic compounds. The purpose of this work was to evaluate the effect of bisubstituted aromatics functional groups on the methanogenic inhibition. The toxicity to acetoclastic methanogenic bacteria has performed in serum flasks, utilizing digested pig manure as inoculums, by measuring cumulative methane production. The results obtained indicate that some general relationships exist between the bisubstituted aromatic structures and their inhibitory effects on methanogenic bacteria. This demonstrates sufficiently that the grafting of hydrophobic or hydrophilic substituent on the benzene or monofunctional aromatic compound, make the obtained compound more or less toxic as the case and that in the same order of toxicity. A significant correlation was obtained indicating that the partitioning of bisubstituted aromatics into lipophilic membranes in bacteria may have a role in the inhibition of methane biosynthesis.

Protein Transduction Domain Mimics: The Role of Aromatic Functionality

Cell-penetrating peptides (CPPs), or protein transduction domains (PTDs), are a special class of membrane-active proteins that can cross the cell membrane with unusual efficiency. They have attracted considerable attention because of their ability to readily cross biological membranes, in spite of their highly charged nature. While the exact mechanism of this transport remains under intense investigation, energy-independent pathways are known. Perhaps the clearest example is the ability of CPPs, and their synthetic mimics, to cross model phospholipid bilayer vesicle membranes. One suggested mechanism implies that, in fact, CPPs like polyarginine (pR) need assistance to cross the membrane. It suggests that hydrophobic counterions complex around the guanidinium-rich backbone, thus “coating” the highly cationic structure with lipophilic moieties. This process has been termed “activation”, in which the lipophilic anion acts as an activator. In a series of detailed studies it was shown that aromatic activators outperform aliphatic ones. For example, sodium 4-(pyren-1-yl)butane-1-sulfonate gave an EC50 (effective concentration to obtain 50% activity) of 6.7 mm whereas the value for sodium dodecane-1sulfonate was 16 mm. Among other activators studied, the larger aromatic counterion, coronene, was not better than pyrene; however, a fullerene analogue was surprisingly effective. While this work beautifully demonstrated the role of various counterions for pR activation, it was not clear if this better activation was due to general hydrophobicity or to the aromatic nature of these activators. There is good reason to think that aromatic functional groups may play a special role, beyond their general hydrophobicity. It is well recognized that membrane proteins are enriched in aromatic amino acids at the membrane surface. Their central hydrophobic core, composed mostly of aliphatic residues, is flanked on both sides by “aromatic belts”. Although this belt is predominantly composed of tryptophan and tyrosine, as opposed to phenylalanine, it was shown that aromatic residues, including N-methylindole, have favorable free energies of insertion into the bilayer interface. This rules out a dominant effect of hydrogen bonding. It was suggested that the flat-rigid shape, p-electronic structure, and associated quadrupolar moments provide unique and highly favorable interactions with the bilayer interface. Specific interactions that have been proposed include p-cation, electrostatic, dipole–dipole, and entropic factors related to bilayer perturbation. Even HIV-TAT, the original protein that initiated the field of small PTDs, requires tryptophan (Trp11) for translocation. [10] Moreover, an oligoarginine consisting of seven arginine residues with a C-terminal tryptophan (R7W) and a TAT48–60 peptide with residue 59 substituted with a tryptophan (TAT48–60P59W) exhibit cellular internalization through energy-independent pathways. Another classical CPP, penetratin (Pen), contains two tryptophan residues. Substitution of tryptophan by phenylalanine (Pen2W2F) did not significantly impact cell uptake. Among the aromatic amino acids, phenylalanine has the unique ability to partition at the interface and in the membrane core. In fact, aromatic residues, especially phenylalanine, are most effective at anchoring proteins in the membrane due to their “special ability” to form and stabilize essential interactions with the polar elements of the bilayer. As a result, aromatic functionality could be a critical element facilitating the interactions between CPPs and the bilayer during transduction. In the past few years, we and others have reported polymers designed to mimic the transduction activity of PTDs. More recently, we demonstrated that these protein transduction domain mimics (PTDMs) have “self-activation” properties when hydrophobic alkyl side chains were built into the copolymers. Here, a new series of PTDMs was designed to determine if an aromatic functionality provides better transduction efficiency than aliphatic ones, at the same relative hydrophobicity. Given the importance of aromatic amino acids in membrane proteins and their interactions with the bilayer, it was proposed that aromatic side chains would make better activators, given equal relative hydrophobicity. Although aromatic groups have been studied in peptidebased CPPs, demonstration of the importance of aromatic functionality in these synthetic analogues is critical to establishing them as appropriate mimics, or PTDMs. By using reversed-phase HPLC to determine side-chain hydrophobicity and EC50 values in a classic transduction experiment, it is demonstrated here that it was possible to differentiate between side-chain hydrophobicity and aromaticity. As shown in Table 1, a series of new PTDM polymers was prepared by ring-opening metathesis polymerization (see the Supporting Information for detailed synthesis and characterization of monomers and polymers). Reversed-phase HPLC, commonly used to evaluate relative hydrophobicity, was [*] Dr. A. Som, A. Reuter, Prof. G. N. Tew Polymer Science & Engineering Department University of Massachusetts 120 Governors Drive, Amherst, MA 01003 (USA) E-mail: tew@mail.pse.umass.edu Homepage: http://www.pse.umass.edu/gtew/index.html

New and extended parameterization of the thermodynamic model AIOMFAC: calculation of activity coefficients for organic-inorganic mixtures containing carboxyl, hydroxyl, carbonyl, ether, ester, alkenyl, alkyl, and aromatic functional groups

Abstract. We present a new and considerably extended parameterization of the thermodynamic activity coefficient model AIOMFAC (Aerosol Inorganic-Organic Mixtures Functional groups Activity Coefficients) at room temperature. AIOMFAC combines a Pitzer-like electrolyte solution model with a UNIFAC-based group-contribution approach and explicitly accounts for interactions between organic functional groups and inorganic ions. Such interactions constitute the salt-effect, may cause liquid-liquid phase separation, and affect the gas-particle partitioning of aerosols. The previous AIOMFAC version was parameterized for alkyl and hydroxyl functional groups of alcohols and polyols. With the goal to describe a wide variety of organic compounds found in atmospheric aerosols, we extend here the parameterization of AIOMFAC to include the functional groups carboxyl, hydroxyl, ketone, aldehyde, ether, ester, alkenyl, alkyl, aromatic carbon-alcohol, and aromatic hydrocarbon. Thermodynamic equilibrium data of organic-inorganic systems from the literature are critically assessed and complemented with new measurements to establish a comprehensive database. The database is used to determine simultaneously the AIOMFAC parameters describing interactions of organic functional groups with the ions H+, Li+, Na+, K+, NH4+, Mg2+, Ca2+, Cl−, Br−, NO3−, HSO4−, and SO42−. Detailed descriptions of different types of thermodynamic data, such as vapor-liquid, solid-liquid, and liquid-liquid equilibria, and their use for the model parameterization are provided. Issues regarding deficiencies of the database, types and uncertainties of experimental data, and limitations of the model, are discussed. The challenging parameter optimization problem is solved with a novel combination of powerful global minimization algorithms. A number of exemplary calculations for systems containing atmospherically relevant aerosol components are shown. Amongst others, we discuss aqueous mixtures of ammonium sulfate with dicarboxylic acids and with levoglucosan. Overall, the new parameterization of AIOMFAC agrees well with a large number of experimental datasets. However, due to various reasons, for certain mixtures important deviations can occur. The new parameterization makes AIOMFAC a versatile thermodynamic tool. It enables the calculation of activity coefficients of thousands of different organic compounds in organic-inorganic mixtures of numerous components. Models based on AIOMFAC can be used to compute deliquescence relative humidities, liquid-liquid phase separations, and gas-particle partitioning of multicomponent mixtures of relevance for atmospheric chemistry or in other scientific fields.

Simultaneous Synthesis of Temperature-Tunable Peptide and Gold Nanoparticle Hybrid Spheres

Hybrid spheres containing peptides and gold nanoparticles have been simultaneously synthesized in water using AG4 (NPSSLFRYLPSD) peptides that acted as a reducing agent to guide the nucleation and growth of gold nanoparticles and a precursor to form sphere-like structure by self-assembly where the size of hybrid spheres is precisely controlled by adjusting the operating temperature. The self-assembled peptide spheres remain stable even after selective removal of the gold nanoparticles by iodide etching. The amino acids containing the aromatic functional group in the peptide sequence significantly affect the construction of sphere structures. The surface of gold nanoparticles containing hybrid spheres has been functionalized using the thiol group linked to biomolecules. The ability to synthesize nanoparticle and self-assembled peptide structures with controlled size and composition in an environmental benign way will allow us to fabricate a new class of multifunctional organic-inorganic hybrid superstructures for various biomedical and electronic applications.

Reproducing crystal binding modes of ligand functional groups using Site-Identification by Ligand Competitive Saturation (SILCS) simulations.

The applicability of a computational method, Site Identification by Ligand Competitive Saturation (SILCS), to identify regions on a protein surface with which different types of functional groups on low-molecular weight inhibitors interact is demonstrated. The method involves molecular dynamics (MD) simulations of a protein in an aqueous solution of chemically diverse small molecules from which probability distributions of fragments types, termed FragMaps, are obtained. In the present application, SILCS simulations are performed with an aqueous solution of 1 M benzene and propane to map the affinity pattern of the protein for aromatic and aliphatic functional groups. In addition, water hydrogen and oxygen atoms serve as probes for hydrogen-bond donor and acceptor affinity, respectively. The method is tested using a set of 7 proteins for which crystal structures of complexes with several high affinity inhibitors are known. Good agreement is obtained between FragMaps and the positions of chemically similar functional groups in inhibitors as observed in the X-ray crystallographic structures. Quantitative capabilities of the SILCS approach are demonstrated by converting FragMaps to free energies, termed Grid Free Energies (GFE), and showing correlation between the GFE values and experimental binding affinities. For proteins for which ligand decoy sets are available, GFE values are shown to typically score the crystal conformation and conformations similar to it more favorable than decoys. Additionally, SILCS is tested for its ability to capture the subtle differences in ligand affinity across homologous proteins, information which may be of utility toward specificity-guided drug design. Taken together, our results show that SILCS can recapitulate the known location of functional groups of bound inhibitors for a number of proteins, suggesting that the method may be of utility for rational drug design.

Protein Affinity Pattern Calculations using Protein-Fragment Site Identification by Ligand Competitive Saturation (SILCS)

We demonstrate the applicability of a computational method, Site Identification by Ligand Competitive Saturation (SILCS) to identify regions on a protein surface with which different classes of functional groups interact. The method involves MD simulations of a protein in an aqueous solution of chemically diverse small molecules. In the present application, SILCS simulations are performed with an aqueous solution of 1 M benzene and propane to map the affinity pattern of the protein for aromatic and aliphatic functional groups. In addition, water hydrogens and oxygen serve as probes for hydrogen bond donor and acceptor functionality, respectively. The method is tested using a set of proteins for which crystal structures of complexes with several high affinity inhibitors are known. SILCS simulations are performed for these proteins and the affinity pattern is obtained as 3D probability distributions of fragment atom types on a 3D-grid surrounding the protein called “FragMaps”. Good agreement is obtained between FragMaps of each type and the positions of chemically similar functional group in inhibitors as observed in the Xray crystallographic structures. For proteins for which inhibitor decoy sets are available, we demonstrate the statistical significance of the SILCS predictions by showing a significantly higher degree of overlap of the ligand atoms in the experimental conformation with the FragMaps. For a few test cases, we correlate the extent of overlap of the ligand functional groups with FragMaps to the experimental binding affinities. SILCS is also shown to capture the subtle differences in protein affinity across homologs, information which may be of utility towards specificity-guided drug design. Taken together, our results suggest that SILCS can recapitulate the location of functional groups of bound inhibitors, suggesting that the method may be of utility for rational drug design.

An advanced oxidation process using ionized gas for wastewater treatment

This study on removing non-degradable materials in wastewater focused primarily on advanced oxidation methods such as ozone, ozone/UV and ozone/H2O2. Wastewater treatment using an ionized gas from plasma has been actively progressing. The ionized gas involves reactive species such as O2+, O2- cluster, O radical and OH radical. Since the ionized gas method has such outstanding characteristics as relatively simple structures, non-calorification, non-toxicity and low electricity consumption, it evidently of interest as a new process. A series of experiments were conducted to demonstrate the feasibility of ionized gas as a useful element for the diminution of nondegradable organic matters. On the other hand, a large amount of organic matters were changed to hydrophilic and the compounds containing aromatic functional group gradually decreased. The results implied that the ionized gas has been able to degrade the non-biodegradable organic matters. Therefore, the oxidation process by using an ionized gas process could be considered as an effective alternative unit in water and wastewater treatment plants.

Characterization of allelopathic compounds from the red tide dinoflagellate Karenia brevis

Blooms and cultures of the red tide dinoflagellate Karenia brevis exude compounds that inhibit the growth of competing phytoplankton, but the identities of these compounds are unknown. We characterized allelopathic compounds from K. brevis using a variety of chromatographic and spectroscopic techniques. K. brevis produces multiple compounds that are inhibitory towards the Gulf of Mexico diatom Asterionellopsis glacialis. However, brevetoxins, potent neurotoxins responsible for massive fish kills and neurotoxic shellfish poisoning in humans, had no effect on A. glacialis growth. We determined that most allelopathic compounds produced by K. brevis are unstable, polar, organic molecules produced at low concentrations, which are either neutral or positively charged. K. brevis also produces a suite of less polar, but more stable compounds that are moderately allelopathic towards A. glacialis. Given that K. brevis encounters a variety of competitor species in the field, the production of multiple allelopathic compounds could provide a broader chemical arsenal to successfully inhibit these competitors. The allelopathic compounds characterized in more detail had molecular weights between 500 and 1000 Da and possessed aromatic functional groups. Metabolic fingerprinting of K. brevis extracts has not yet led to identification of specific compound(s) responsible for allelopathy. Our results indicate that the ability of K. brevis to outcompete co-occurring phytoplankton may be facilitated by the production of multiple allelopathic compounds.

Site-specific orthogonal labeling of the carboxy terminus of alpha-tubulin.

A fluorescent probe has been attached to the carboxy terminus of the alpha-subunit of alpha,beta-tubulin by an enzymatic reaction followed by a chemical reaction. The unnatural amino acid 3-formyltyrosine is attached to the carboxy terminus of alpha-tubulin through the use of the enzyme tubulin tyrosine ligase. The aromatic aldehyde of the unnatural amino acid serves as an orthogonal electrophile that specifically reacts with a fluorophore containing an aromatic hydrazine functional group, which in this case is 7-hydrazino-4-methyl coumarin. Conditions for covalent bond formation between the unnatural amino acid and the fluorophore are mild, allowing fluorescently labeled tubulin to retain its ability to assemble into microtubules. A key feature of the labeling reaction is that it produces a red shift in the fluorophore's absorption and emission maxima, accompanied by an increase in its quantum yield; thus, fluorescently labeled protein can be observed in the presence of unreacted fluorophore. Both the enzymatic and coupling reaction can occur in living cells. The approach presented here should be applicable to a wide variety of in vitro systems.

Multiscale characterization of pyritized plant tissues in blueschist facies metamorphic rocks

Pyritized plant tissues with well-preserved morphology were studied in rocks from Vanoise (western Alps, France) that experienced high-pressure, low-temperature metamorphic conditions in the blueschist facies during the Alpine orogeny. Organic and inorganic phases composing these fossils were characterized down to the nanometer scale by Raman microspectroscopy, scanning transmission X-ray microscopy and transmission electron microscopy. The graphitic but disordered organic matter composing these fossils is chemically and structurally homogeneous and mostly contains aromatic functional groups. Its original chemistry remains undefined likely because it was significantly transformed by diagenetic processes and/or thermal degradation during metamorphism. Various mineral phases are closely associated with this organic matter, including sulphides such as pyrite and pyrrhotite, carbonates such as ankerite and calcite, and iron oxides. A tentative time sequence of formation of these diverse mineral phases relative to organic matter decay is proposed. The absence of traces of organic matter sulphurization, the pervasive pyritization of the vascular tissues and the presence of ankerite suggest that the depositional/diagenetic environment of these metasediments was likely rich in reactive iron. Fe-sulphides and ankerite likely precipitated early and might have promoted the preservation of the fossilized biological soft tissues by providing mechanical resistance to compaction during diagenesis and subsequent metamorphism. In contrast, iron oxides which form rims of 100-nm in thickness at the interface between organic matter and Fe-sulphides may result from metamorphic processes. This study illustrates that it may be possible in some instances to deconvolve metamorphic from diagenetic imprints and opens new avenues to better constrain processes that may allow the preservation of organic fossils during diagenesis and metamorphism.

Diameter‐ and Metallicity‐Selective Enrichment of Single‐Walled Carbon Nanotubes Using Polymethacrylates with Pendant Aromatic Functional Groups

Current methods for the synthesis of single-walled nanotubes (SWNTs) produce mixtures of semiconducting (sem-) and metallic (met-) nanotubes. Most approaches to the chemical separation of sem-/met-SWNTs are based on small neutral molecules or conjugated aromatic polymers, which characteristically have low separation/dispersion efficiencies or present difficulties in the postseparation removal of the polymer so that the resulting field-effect transistors (FETs) have poor performance. In this Full Paper, the use of three polymethacrylates with different pendant aromatic functional groups to separate cobalt-molybdenum catalyst (CoMoCAT) SWNTs according to their metallicity and diameters is reported. UV/Vis/NIR spectroscopy indicates that poly(methyl-methacrylate-co-fluorescein-o-acrylate) (PMMAFA) and poly(9-anthracenylmethyl-methacrylate) (PAMMA) preferentially disperse semiconducting SWNTs while poly(2-naphthylmethacrylate) (PNMA) preferentially disperses metallic SWNTs, all in dimethylforamide (DMF). Photoluminescence excitation (PLE) spectroscopy indicates that all three polymers preferentially disperse smaller-diameter SWNTs, particularly those of (6,5) chirality, in DMF. When chloroform is used instead of DMF, the larger-diameter SWNTs (8,4) and (7,6) are instead selected by PNMA. The solvent effects suggest that diameter selectivity and change of polymer conformation is probably responsible. Change of the polymer fluorescence upon interaction with SWNTs indicates that metallicity selectivity presumably results from the photon-induced dipole-dipole interaction between polymeric chromophore and SWNTs. Thin-film FET devices using semiconductor-enriched solution with PMMAFA have been successfully fabricated and the device performance confirms the sem-SWNTs enrichment with a highly reproducible on/off ratio of about 10(3).

Effect of pretreatment by different organic solvents on esterification activity and conformation of immobilized Pseudomonas cepacia lipase

Abstract Experiments were carried out to investigate the effect of pretreatment by organic solvents with different hydrophobicities, functional groups and molecular constitutions as activation agents on initial esterification activity and secondary structure of immobilized Pseudomonas cepacia lipase. The results showed that esterification activity of immobilized P. cepacia lipase treated with organic solvents containing –C O– and –C N– functional groups was highest, followed by the one treated with –C–C– functional groups but the lowest with –OH and aromatics functional groups. An organic solvent with a branched structure was more favorable compared with a straight chain in terms of enhancing enzyme activity. Conformational studies via Fourier transform-infrared spectroscopy indicated that the catalytic activity variance was attributed to the secondary structure changes for immobilized P. cepacia lipase treated with organic solvents. Moreover, the effects of moisture, pH and temperature on the esterification activity of immobilized P. cepacia lipase were also addressed.

Chemical functionalities of high and low sulfur Australian coals: A case study using micro attenuated total reflectance–Fourier transform infrared (ATR–FTIR) spectrometry

The macerals in bituminous coals with varying organic sulfur content from the Early Permian Greta Coal Measures at three locations (Southland Colliery, Drayton Colliery and the Cranky Corner Basin), in and around the Sydney Basin (Australia), have been studied using light-element electron microprobe (EMP) analysis and micro-ATR–FTIR. Electron microprobe analysis of individual macerals reveals that the vitrinite in both the Cranky Corner Basin and Drayton Colliery (Puxtrees seam) samples have similar carbon contents (ca. 78% C in telocollinite), suggesting that they are of equivalent rank. However, the Cranky Corner coals have anomalously low vitrinite reflectance (down to 0.45%) vs. the Drayton materials (ca. 0.7%). They also have very high organic S content (3–6.5%) and lower O content (ca. 10%) than the equivalent macerals in the Drayton sample (0.7% S and 15.6% O). A study was carried out to investigate the impacts of the high organic S on the functional groups of the macerals in these two otherwise iso-rank, stratigraphically-equivalent seams. An iso-rank low-S coal from the overlying Wittingham Coal Measures near Muswellbrook and coals of slightly higher rank from the Greta Coal Measures at Southland Colliery near Cessnock were also evaluated using the same techniques to extend the data set. Although the telocollinite in the Drayton and Cranky Corner coals have very similar carbon content (ca.78% C), the ATR–FTIR spectra of the vitrinite and inertinite macerals in these respectively low S and high S coals show some distinct differences in IR absorbance from various aliphatic and aromatic functional groups. The differences in absorbance of the aliphatic stretching bands (2800–3000 cm −1) and the aromatic carbon (C C) peak at 1606 cm −1 are very obvious. Compared to that of the Drayton sample (0.7% S and 15% O), the telocollinite of the Cranky Corner coal (6% S and 10% O) clearly shows: (i) less absorbance from OH groups, represented by a broad region around 3553 cm −1, (ii) much stronger aliphatic C–H absorbance (stretching modes around 3000–2800 cm −1 and bending modes around 1442 cm −1) and (iii) less absorbance from aromatic carbon functional groups (peaking at 1606 cm −1). Evaluation of the iso-rank Drayton and Cranky Corner coals shows that: (i) the aliphatic C–H absorbances decrease with increasing oxygen content but increase with increasing organic S content and (ii) the aromatic H to aliphatic H ratio (Har/Hali) for the telocollinite increases with (organic) O%, but decreases progressively with increasing organic S. The high organic S content in the maceral appears to be accompanied by a greater proportion of aliphatic functional groups, possibly as a result of some of the O within maceral ring structures in the high S coal samples being replaced.

Anti-Leukemic Activity of Mitochondrially-Directed Asymmetrical 2-2'-Binaphthoquinones.

Abstract 4799 IntroductionBinaphthoquinones are unique molecules consisting of two linked naphthoquinone units. Previously, we regiospecifically synthesized a series of asymmetrical 2,2'-binaphthoquinones, which possess HIV integrase inhibitory activity. Potent activity against non-HIV-infected CEM-T4 acute lymphoblastic leukemia cells prompted us to investigate other cytotoxic mechanisms of these compounds. A genome-wide yeast screen uncovered that mitochondrial-related genes are required for sensitivity and resistance to these agents. Furthermore, by generating reactive oxygen species (ROS), biquinones halted yeast growth which was rescued by addition of N-acetylcysteine. Therefore, as part of our efforts to identify new compounds with anti-leukemic activity, we hypothesized that 2,2'-binaphthoquinones would be able to kill leukemic cells by interference with mitochondrial function. The majority of studies on antineoplastic effects of quinones have focused on benzoquinones, anthraquinones or monomeric naphthoquinones. However, nothing is published on the anti-leukemic action of asymmetrical 2,2'-binaphthoquinones, in which two different mononaphthoquinones are attached at the quinone double bond. Biquinones possess four carbonyl groups that have the potential to generate a greater number of ROS per one mole of quinone, and thereby cause more effective oxidative stress, than their monoquinone counterparts. In addition, the potential differences in cytotoxicities between monomeric and dimeric naphthoquinones result from many parameters, including the number of units, planarity, and the specific nature and pattern of aromatic functional groups. Materials and MethodsSeventeen of our biquinones were dissolved in DMSO and incubated with four leukemia cell lines grown under standard conditions. All cultures were maintained with a constant DMSO concentration. A standard MTT cell proliferation assay was used to identify IC50 values. MV411 cells were incubated for 42-49 hours (2 nights) with two of the most potent compounds, biquinone #7 (BiQ7) and biquinone #10 (BiQ10), and they were assayed and analyzed by flow cytometry for loss of mitochondrial membrane potential (via rhodamine 123 staining), as well as a variety of apoptosis markers such as exposed phosphatidylserine, activated caspases, and sub-2n DNA increases. Simultaneously, preliminary toxicology experiments have been performed on mice. ResultsThe IC50 values for both compounds were less than 5 micromolar (μM) against all four cell lines. For subsequent experiments, the cells were treated with either 5 μM BiQ7 or 5 μM BiQ10. A loss of mitochondrial membrane electrochemical potential, as expressed and evidenced by substantial decrease in fluorescence intensity of Rhodamine 123, was observed in 98-100% of the treated cells compared to control (5%). Loss of plasma membrane phosphatidylserine asymmetry was observed via Annexin V- PE (with 7AAD) staining in 94-95% of the treated cells and in only 18% of the control cells. Furthermore, the treated cells showed increases in staining for activated caspases 3 & 7 (BiQs 96-98%; control 10%). Finally, the cell cycle analyses via propidium iodide showed increases in sub-2n DNA in the treated cells compared to the control (control 12%; BiQ7 34%; and BiQ10 54%). Importantly, the preliminary toxicology results in mice suggest selectivity for neoplastic cells since no cytopenia or obvious end organ toxicity was observed with injection of 600 μM binaphthoquinones intraperitoneally daily for three weeks. ConclusionOur study shows that this new class of compounds possesses promising in vitro anti-leukemic effects by targeting mitochondrial membrane permeabilization, which occurs early in the apoptotic program and is located downstream of most identified chemotherapy resistance mechanisms in hematologic malignancies. In vivo experiments in xenograft model and ex vivo experiments on primary human cells are planned. Disclosures:No relevant conflicts of interest to declare.

Synthesis and Biological Evaluation of New Nanomolar Competitive Inhibitors of Helicobacter pylori Type II Dehydroquinase. Structural Details of the Role of the Aromatic Moieties with Essential Residues

The shikimic acid pathway is essential to many pathogens but absent in mammals. Enzymes in its pathway are therefore appropriate targets for the development of novel antibiotics. Dehydroquinase is the third enzyme of the pathway, catalyzing the reversible dehydratation of 3-dehydroquinic acid to form 3-dehydroshikimic acid. Here we present the synthesis of novel inhibitors with high affinity for Helicobacter pylori type II dehydroquinase and efficient inhibition characteristics. The structure of Helicobacter pylori type II dehydroquinase in complex with the most potent inhibitor shows that the aromatic functional group interacts with the catalytic Tyr22 by pi-stacking, expelling the Arg17 side chain, which is essential for catalysis, from the active site. The structure therefore explains the favorable properties of the inhibitor and will aid in design of improved antibiotics.

Properties of a Non-Aromatic Epoxy Polymer-Based Monolithic Capillary Column for μ-HPLC

We report the chromatographic properties of a new type of epoxy polymer-based monolithic capillary column, the Tetrad-C column. The column was prepared by a completely new method—reaction of a tetra-functional epoxy monomer, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane (trade name Tetrad-C), with a diamine, 4-[(4-aminocyclohexyl)methyl)cyclohexane (BACM). This polymer monolith has no aromatic functional groups reducing chromatographic performance. The columns were carefully observed by scanning electron microscopy and evaluated chromatographically by use of a μ-HPLC system. It was found that morphological control of the epoxy polymer-based monolith was possible simply by changing the polymerization conditions, i.e., the polymerization temperature and/or the relative amounts of porogenic solvent and BACM. Another advantage was that volumetric shrinkage of the tetra-functional epoxy-based monolith during the polymerization reaction was much less than for the tri-functional epoxy-based monolithic (TEPIC) column reported in our previous paper. A Tetrad-C column 200 mm long afforded up to 10,000 plates for alkylbenzenes in reversed-phase-mode. This column can also work in HILIC mode, although the hydrophobicity of the column was greater than that of the TEPIC column. Heat treatment (160 °C for 2 h; to eliminate residual, unreacted, functional groups) had a negligible effect on column performance, indicating the columns were thermally stable.

Hyperbranched Polymers with a Degree of Branching of 100% Prepared by Catalyst Transfer Suzuki−Miyaura Polycondensation

Hyperbranched polymers with a degree of branching of 100% were prepared by catalyst transfer Suzuki-Miyaura polymerization of AB(2) monomers carrying one boronic acid and two aromatic bromo functional groups; in contrast, Suzuki-Miyaura polymerization of the same AB(2) monomers using a traditional catalyst afforded hyperbranched polymers with a branching degree of only approximately 56%. This is a nice example of controlling the topology of hyperbranched polymers via the catalyst.

Cocoa Industrial Debris Composting in Soil and Earthworm Breeding

Toasted husk, the main cocoa (Theobroma cacao L.) industrialization by-product, was added to pots in different husk doses with 1 kg of topsoil from a cocoa plantation (Umbrisol) and then treated with 5 earthworms (Pontoscolex corethrurus) during 60 days, in a greenhouse experiment. Amendment enhanced (p < 0.5) soil organic matter, water retention, bulk density. Best dose for earthworms breeding was 63.3 g·kg−1 (1,840 g·m−2). Husk was used to feed 10 earthworms•m−2 in an Eutric Fluvisol at Villahermosa, Tabasco, Mexico; in 67 days, produced 58 worms on husk 920 g·m−2, or 54 worms on 1150 g·m−2 husk. Husk was then subjected to a conventional pile composting, and the compost was used to feed 10 earthworms m−2 in the Eutric Fluvisol; those fed with 920 g·m−2 yielded 300 worms·m−2. The product of this last experiment was used as amendment (dose 920 g·m−2) in a 30,000 plants·ha−1 maize crop on a highland Mollisol: yields were 954 kg·ha−1 without amendment, 1137 kg·ha−1 amended. As for humification, the main quality parameters from the materials and soils studied, and purified fractions of humic and fulvic acids were studied by visible and infrared (FTIR) spectroscopy. The major changes observed in the humic acid fraction suggest that the improvement in soil organic matter properties could be related to the increase in aromatic, oxygen-containing and amide functional groups, as could correspond to selective biodegradation process concomitant to incorporation of microbial products into oxidized, altered husk lignin fractions.

Structure characteristics contributing to flame retardancy in diazo modified novolac resins

The physical characteristics of two modified novolac resins (carbonyl phenyl azo novolac resin; CPAN and 4-(4-hydroxyphenyl azo) benzyl ester novolac resin; HPDEN) bearing nitrogen and aromatic functional groups by diazo-coupling or esterification in the branch structure of phenol novolac resin were examined. Presence of the modifiers raised the phenolic decomposition temperature (5% weight loss) from 300 °C (pure Phenolic) to 330 °C and 380 °C, while the char residue increased from 45% to 56% and 68%, respectively. The kinetics for thermal degradation energies ( E a) also rose from 151 kJ/mol K to 254 kJ/mol K (CPAN) and 273 kJ/mol K (HPDEN). The retarded decomposition kinetics is attributed both to the increase of crosslink densities and high aromatic content in the derivative resins. On the other hand, the diazo-coupling or phenyl diazenyl ester produces non-combustible gases (N 2, CO 2 and CO) during formation of aromatic char which dilute the ambient oxygen gas. Both the production of gases and the retarded kinetics due to cross-linking are definitive for the improved flame resistance.