Browsing by Subject "ACID"

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  • Parmentier, Dries; Paradis, Sarah; Metz, Sybrand J.; Wiedmer, Susanne K.; Kroon, Maaike C. (2016)
    This work describes for the first time a continuous process for selective metal extraction with an ionic liquid (IL) at room temperature. The hydrophobic fatty acid based IL tetraoctylphosphonium oleate ([P-8888][oleate]) was specifically chosen for its low viscosity and high selectivity towards transition metals. Applying [P-8888][oleate] for continuous metal ion extraction with 0.1 M sodium oxalate for regeneration resulted in a process with good and stable extraction efficiencies over time. The selectivity of the IL resulted in a process in which cobalt was selectively removed from two mixed salt solutions (Co/Na, Ca/Co/K) to obtain a pure cobalt stream after stripping the IL. The performed experiments showed that the contact time of the IL for extraction and stripping strongly influenced the achieved efficiencies. The stability of the IL was tested and it was shown that the fatty acid based IL was stable for the duration of the experiment. Liposome tests showed that the IL is very hydrophobic, which limits its leakage towards the water phase, but also results in a higher toxicity towards cell membranes. Economic analysis shows that the IL based process is not (yet) economical compared to ion-exchange resins, in case demineralised water is the only product. However, if the recovery of valuable metals is also taken into account and/or if brine disposal is an issue, then continuous IL metal extraction systems must be regarded as promising alternatives. (C) 2016 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.
  • Ma, Hao; Zhou, Bo; Li, Yiqun; Argyropoulos, Dimitris S. (2012)
  • Rico del Cerro, Daniel; Koso, Tetyana V.; Kakko, Tia; King, Alistair W. T.; Kilpeläinen, Ilkka (2020)
    Herein, we demonstrate the activation of commercial chemical cellulose pulps towards chemical modification by a pre-treatment step with tetrabutylphosphonium acetate ([P-4444][OAc]). A heterogeneous (non-dissolving) pre-treatment was applied allowing for a significant reduction in crystallinity, without concomitant formation of the thermodynamically stable cellulose II. An increase in chemical reactivity was demonstrated using two model reactions; (1) acetylation (organic swelling conditions), where high degrees of substitution (DS) were obtained without the need for a catalyst, and (2) 4-acetamido-TEMPO oxidation (aqueous swelling conditions), where significant degrees of oxidation (DO) were obtained, beyond those for the untreated pulps. In both tests a notable improvement in cellulose reactivity was observed. Regioselectivity of acetylation was assessed using 2D NMR for one low and one high DS sample. The low DS showed a small degree of acetylation of the 6-OH, whereas, the high DS from the pre-treated sample showed mainly mixtures of triacetate and diacetates. Important mechanistic information is attained for future development of aqueous and organic-based reactions involving this ionic liquid pre-treatment.
  • Tossavainen, Marika; Nykänen, Anne; Valkonen, Kalle Santeri; Ojala, Anne; Silja, Kostia; Romantschuk, Martin (2017)
    Growth and fatty acid production of microalga Selenastrum sp. with associated bacteria was studied in lab-scale experiments in three composting leachate liquids. Nutrient reduction in cultures was measured at different initial substrate strengths. A small, pilot-scale photobioreactor (PBR) was used to verify labscale results. Similar growth conditions supported growth of both Selenastrum and bacteria. CO2 feed enhanced the production of biomass and lipids in PBR (2.4 g L-1 and 17% DW) compared to lab-scale (0.1-1.6 g L-1 and 4.0-6.5% DW) experiments. Also prolonged cultivation time increased lipid content in PBR. At both scales, NH4-N with an initial concentration of ca. 40 mg L-1 was completely removed from the biowaste leachate. In lab-scale, maximal COD reduction was over 2000 mg L-1, indicating mixotrophic growth of Selenastrum. Co-cultures are efficient in composting leachate liquid treatment, and conversion of waste to biomass is a promising approach to improve the bioeconomy of composting plants. (C) 2017 The Authors. Published by Elsevier Ltd.
  • Nieminen, H. J.; Ylitalo, T.; Karhula, S.; Suuronen, J. -P.; Kauppinen, S.; Serimaa, R.; Haeggstrom, E.; Pritzker, K. P. H.; Valkealahti, M.; Lehenkari, P.; Finnila, M.; Saarakkala, S. (2015)
    Objective: Collagen distribution within articular cartilage (AC) is typically evaluated from histological sections, e.g., using collagen staining and light microscopy (LM). Unfortunately, all techniques based on histological sections are time-consuming, destructive, and without extraordinary effort, limited to two dimensions. This study investigates whether phosphotungstic acid (PTA) and phosphomolybdic acid (PMA), two collagen-specific markers and X-ray absorbers, could (1) produce contrast for AC X-ray imaging or (2) be used to detect collagen distribution within AC. Method: We labeled equine AC samples with PTA or PMA and imaged them with micro-computed tomography (micro-CT) at pre-defined time points 0, 18, 36, 54, 72, 90, 180, 270 h during staining. The micro-CT image intensity was compared with collagen distributions obtained with a reference technique, i.e., Fourier-transform infrared imaging (FTIRI). The labeling time and contrast agent producing highest association (Pearson correlation, BlandeAltman analysis) between FTIRI collagen distribution and micro-CT -determined PTA distribution was selected for human AC. Results: Both, PTA and PMA labeling permitted visualization of AC features using micro-CT in non-calcified cartilage. After labeling the samples for 36 h in PTA, the spatial distribution of X-ray attenuation correlated highly with the collagen distribution determined by FTIRI in both equine (mean +/- S.D. of the Pearson correlation coefficients, r = 0.96 +/- 0.03, n = 12) and human AC (r = 0.82 +/- 0.15, n = 4). Conclusions: PTA-induced X-ray attenuation is a potential marker for non-destructive detection of AC collagen distributions in 3D. This approach opens new possibilities in development of non-destructive 3D histopathological techniques for characterization of OA. (C) 2015 The Authors. Published by Elsevier Ltd and Osteoarthritis Research Society International.
  • Das, Biswanath; Al-Hunaiti, Afnan; Sanchez-Eguia, Brenda N.; Zeglio, Erica; Demeshko, Serhiy; Dechert, Sebastian; Braunger, Steffen; Haukka, Matti; Repo, Timo; Castillo, Ivan; Nordlander, Ebbe (2019)
    The new di- and tetranuclear Fe(III) mu-oxido complexes [Fe-4(mu-O)(4) (PTEBIA)(4)]CF3SO3)(4)(CH3CN)(2)] (1a) , [Fe-2(mu-O)Cl-2(PTEBIA)(2)(CF3SO3)(2) (1b), and [Fe-2(mu-O)(HCOO)(2)(PTEBIA)(2)](ClO4)(2) (MeOH) (2) were prepared from the sulfur-containing ligand (2-((2,4-dimethylphenyl)thiO)-N,N-bis ((1-methyl-benzimidazol-2-yl)methyl)ethanamine (PTEBIA). The tetrairon complex 1a features four mu-oxido bridges, while in dinuclear 1b, the sulfur moiety of the ligand occupies one of the six coordination sites of each Fe(III) ion with a long Fe-S distance of 2.814(6) angstrom . In 2, two Fe(III) centers are bridged by one oxido and two formate units, the latter likely formed by methanol oxidation. Complexes 1a and 1 b show broad sulfur-toiron charge transfer bands around 400-430 nm at room temperature, consistent with mononuclear structures featuring Fe-S interactions. In contrast, acetonitrile solutions of 2 display a sulfur-to-iron charge transfer band only at low temperature (228 K) upon addition of H2O2/CH3COOH, with an absorption maximum at 410 nm. Homogeneous oxidative catalytic activity was observed for 1a and 1b using H2O2 as oxidant, but with low product selectivity. High valent iron-oxo intermediates could not be detected by UV-vis spectroscopy or ESI mass spectrometry. Rather, evidence suggest preferential ligand oxidation, in line with the relatively low selectivity and catalytic activity observed in the reactions.
  • Wester, Niklas; Mikladal, Bjorn F.; Varjos, Ilkka; Peltonen, Antti; Kalso, Eija; Lilius, Tuomas; Laurila, Tomi; Koskinen, Jari (2020)
    A disposable electrochemical test strip for the quantitative point-of-care (POC) determination of acetaminophen (paracetamol) in plasma and finger-prick whole blood was fabricated. The industrially scalable dry transfer process of single-walled carbon nanotubes (SWCNTs) and screen printing of silver were combined to produce integrated electrochemical test strips. Nafion coating stabilized the potential of the Ag reference electrode and enabled the selective detection in spiked plasma as well as in whole blood samples. The test strips were able to detect acetaminophen in small 40 mu L samples with a detection limit of 0.8 mu M and a wide linear range from 1 mu M to 2 mM, well within the required clinical range. After a simple 1:1 dilution of plasma and whole blood, a quantitative detection with good recoveries of 79% in plasma and 74% in whole blood was achieved. These results strongly indicate that these electrodes can be used directly to determine the unbound acetaminophen fraction without the need for any additional steps. The developed test strip shows promise as a rapid and simple POC quantitative acetaminophen assay.
  • Altinci, Pinar; Mutluay, Murat; Tjäderhane, Leo; Tezvergil-Mutluay, Arzu (2018)
    Objective: Matrix metalloproteinases (MMPs) and cysteine cathepsins (CCs) are two distinct enzymatic pathways responsible for the degradation of collagen fibrils in demineralized dentin. NaF and KF have been shown to inhibit salivary MMP-2, -9 and CCs. This study investigated the inhibitory effect of calcium fluoride (CaF2) on the dentin matrix-bound MMPs and CCs. Design: Phosphoric acid (10%)-demineralized dentin beams (1 x 2 x 6 mm) were incubated at 37 degrees C in an 1 ml of artificial saliva (AS, control), or AS with 6, 12, 24, 48, 120. 179 and 238 mM F containing CaF2 (n = 10/group) for 1, 7 and 21 days. All groups were further incubated in AS only for 6 months. Total MMP activity, dry mass loss, CTX and hydroxyproline (HYP) analyses were performed after each incubation. The beams were examined under scanning electron microscopy (SEM). MMP-2 and MMP-9 activities were screened with gelatin zymography. Data were analyzed by using ANOVA and Tukey HSD tests (p = .05). Results: The total MMP activity was similar for all groups after 21 days and 6 months. After 21 days, the cumulative mass loss and CTX levels were lower compared to control for the CaF2 48 and CaF2 120 mM, respectively (p <.05). After 6 months, no significant difference was detected in the dry mass loss and CTX compared to the control (p > .05), whereas HYP level was higher with F 24 and 238 mM groups. CaF2-like minerals were observed on the beams under SEM. There was no gelatinase inhibition in zymography. Conclusion: CaF2 does not prevent the degradation of demineralized dentin matrices due to the catalytic activity of MMPs and CCs.
  • Holding, Ashley J.; Parviainen, Arno; Kilpeläinen, Ilkka; Soto, Ana; King, Alistair W. T.; Rodriguez, Hector (2017)
    Hydrophobic, long-chain tetraalkylphosphonium acetate salts (ionic liquids) were combined with a dipolar aprotic co-solvent, dimethylsulfoxide (DMSO), and the feasibility of these solvent systems for cellulose dissolution and regeneration was studied. A 60 : 40 w/w mixture of the ionic liquid tetraoctylphosphonium acetate ([P-8888][OAc]) and DMSO was found to dissolve up to 8 wt% cellulose, whilst trioctyl(tetradecyl) phosphonium acetate ([P-14888][OAc]) dissolved up to 3 wt% cellulose. Water (an anti-solvent for cellulose) was found to give rise to biphasic liquid-liquid systems when combined with these mixtures, yielding an upper phase rich in ionic liquid and a lower aqueous phase. The liquid-liquid equilibria of the ternary systems were experimentally determined, finding that DMSO strongly partitioned towards the aqueous phase. Thus, a process scheme involving simultaneous regeneration of cellulose and recycling of the solvent system was envisioned, and demonstrated on a large scale using [P-8888] [OAc]. A large portion of the ionic liquid (ca. 60 wt%) was directly recovered via phase separation, with a further 37 wt% being recovered from the swollen cellulose phase and residual materials, bringing recovery to 97%. XRD analysis of the recovered cellulose materials showed a loss of crystallinity and conversion from Cellulose I to Cellulose II. Non-dissolving compositions of ionic liquid and DMSO did not affect cellulose crystallinity after cellulose pulp treatment.
  • Hassan, Alaa A.; Mohamed, Nasr K.; Aly, Ashraf A.; Tawfeek, Hendawy N.; Bräse, Stefan; Nieger, Martin (2019)
    Diazenyl 1,2,4-triazol-5(4H)-thione derivatives were synthesized in good yields via Eschenmoser-coupling reaction and nucleophilic attack between 1,4-disubstituted thiosemicarbazides and 2,3,5,6-tetrachloro-1,4-benzoquinone (p-CHL). The structure of the synthesized compounds was confirmed by IR, NMR and mass spectral data as well as single crystal X-ray analysis.
  • Tenca, Andrea; de Bortoli, Nicola; Mauro, Aurelio; Frazzoni, Marzio; Savarino, Edoardo; Massironi, Sara; Russo, Salvatore; Bertani, Lorenzo; Marchi, Santino; Penagini, Roberto (2017)
    Background: The factors influencing new markers of gastro-esophageal reflux disease detected by impedance-pH monitoring - mean nocturnal baseline impedance (MNBI) and post-reflux swallow-induced peristaltic wave (PSPW) index - need to be evaluated. Aim: To compare endoscopy-negative heartburn with chronic autoimmune atrophic gastritis (CAAG). Materials and methods: 24 patients with CAAG, 25 with non-erosive reflux disease (NERD) and 25 with functional heartburn (FH) were included. In all patients the main impedance-pH monitoring parameters were calculated. Results: CAAG and NERD patients had a number of reflux events (non-acid ones being more common among the former group) which was higher than that found in FH (p <0.001). MNBI decreased progressively in FH (> 3000 Ohm), CAAG (> 2000 Ohm) and NERD (<1000 Ohm) patients (p = 0.0046). The PSPW index was similar between CAAG and NERD patients but significantly lower in comparison to FH (p <0.0001). Conclusion: Patients with CAAG have evidence of non-acid reflux based on the high number of reflux events and confirmed by low values of MNBI and PSPW index. MNBI is a strong marker of acid/non-acid reflux-induced mucosal damage, whereas the PSPW index can reliably discriminate patients with reflux from those with FH, independently of the acidity of refluxate. (C) 2017 Editrice Gastroenterologica Italiana S.r.l. Published by Elsevier Ltd. All rights reserved.
  • Niemela, Tytti Maaria; Tulamo, Riitta-Mari; Uriel Carmona, Jorge; Lopez, Catalina (2019)
    Background: Inflammatory and degenerative activity inside the joint can be studied in vivo by analysis of synovial fluid biomarkers. In addition to pro-inflammatory mediators, several anabolic and anti-inflammatory substances are produced during the disease process. They counteract the catabolic effects of the pro-inflammatory cytokines and thus diminish the cartilage damage. The response of synovial fluid biomarkers after intra-articular hyaluronan injection, alone or in combination with other substances, has been examined only in a few equine studies. The effects of hyaluronan on some pro-inflammatory mediators, such as prostaglandin E-2, have been documented but especially the effects on synovial fluid anti-inflammatory mediators are less studied. In animal models hyaluronan has been demonstrated to reduce pain via protecting nociceptive nerve endings and by blocking pain receptor channels. However, the results obtained for pain-relief of human osteoarthritis are contradictory. The aim of the study was to measure the synovial fluid IL-1ra, PDGF-BB, TGF-beta(1) and TNF-alpha concentrations before and after surgically induced cartilage defect, and following intra-articular hyaluronan injection in horses. Eight Standardbred horses underwent bilateral arthroscopic surgeries of their intercarpal joints under general anaesthesia, and cartilage defect was created on the dorsal edge of the third carpal bone of one randomly selected intercarpal joint of each horse. Five days post-surgery, one randomly selected intercarpal joint was injected intra-articular with 3 mL HA (20 mg/mL). Results: Operation type had no significant effect on the synovial fluid IL-1ra, PDGF-BB, TGF-beta(1) and TNF-alpha concentrations but compared with baseline, synovial fluid IL-1ra and TNF-alpha concentrations increased. Intra-articular hyaluronan had no significant effect on the biomarker concentrations but a trend of mild improvement in the clinical signs of intra-articular inflammation was seen. Conclusions: Creation of the cartilage defect and sham-operation lead to an increase of synovial fluid IL-1ra and TNF-alpha concentrations but changes in concentrations of anabolic growth factors TGF-beta(1) and PDGF-BB could not be documented 5 days after the arthroscopy. Intra-articular hyaluronan was well tolerated. Further research is needed to document possible treatment effects of intra-articular hyaluronan on the synovial fluid biomarkers of inflammation and cartilage metabolism.
  • Draper, Danielle C.; Myllys, Nanna; Hyttinen, Noora; Moller, Kristian H.; Kjaergaard, Henrik G.; Fry, Juliane L.; Smith, James N.; Kurten, Theo (2019)
    NO3 radical oxidation of most monoterpenes is a significant source of secondary organic aerosol (SOA) in many regions influenced by both biogenic and anthropogenic emissions, but there are very few published mechanistic studies of NO3 chemistry beyond simple first generation products. Here, we present a computationally derived mechanism detailing the unimolecular pathways available to the second generation of peroxy radicals following NO3 oxidation of Delta-3-carene, defining generations based on the sequence of peroxy radicals formed rather than number of oxidant attacks. We assess five different types of unimolecular reactions, including peroxy and alkoxy radical (RO2 and RO) hydrogen shifts, RO2 and RO ring closing (e.g., endoperoxide formation), and RO decomposition. Rate constants calculated using quantum chemical methods indicate that this chemical system has significant contribution from both bimolecular and unimolecular pathways. The dominant unimolecular reactions are endoperoxide formation, RO H-shifts, and RO decomposition. However, the complexity of the overall reaction is tempered as only 1 or 2 radical propagation pathways dominate the fate of each radical intermediate. Chemical ionization mass spectrometry (CIMS) measurements using the NO3- reagent ion during Delta-3-carene + NO3 chamber experiments show products consistent with each of the three types of unimolecular reactions predicted to be important from the computational mechanism. Moreover, the SIMPOL group contribution method for predicting vapor pressures suggests that a majority of the closed-shell products inferred from these unimolecular reactions are likely to have low enough vapor pressure to be able to contribute to SOA formation.
  • Khan, Daulat Haleem; Bashir, Sajid; Khan, Muhammad Imran; Figueiredo, Patricia; Santos, Hélder A.; Peltonen, Leena (2020)
    The aim of the present study was to prepare niosomal formulations for dual drug therapy of ceftriaxone sodium and poorly water-soluble rifampicin by the ecological probe sonication method. Pluronic L121 and Span 60 were used as surface active agents and the optimization of the composition was made with the aid of Design of Experiment (DoE) concept. Concentration levels of charge inducing agent, dicetylphosphate (DCP), and Pluronic L121 were studied as variables. Prepared niosomes with varying concentrations of DCP and Pluronic L121 resulted in small sized niosomes with sizes ranging from 165 nm to 893 nm. During the four weeks stability testing, the particle sizes of the empty niosomes were reduced, while the particle sizes of the drug loaded niosomes were increased very slightly. The optimized formulations resulted in stable niosomes with high drug entrapment efficiencies: entrapment efficiency was 99% for rifampicin and 96% for ceftriaxone. All the niosomal formulations showed faster in vitro drug release rates as compared to bulk drug formulations. In conclusion, ceftriaxone and rifampicin loaded niosomes prepared with Pluronic L121 and Span 60 resulted in stable, small sized niosomes with high drug entrapment efficiencies and improved drug release profiles.
  • Dilokpimol, Adiphol; Mäkelä, Miia Riitta; Varriale, Simona; Zhou, Miaomiao; Cerullo, Gabriella; Gidijala, Loknath; Hinkka, Harri Tapio; Brás, Joana L.A.; Jütten, Peter; Piechot, Alexander; Verhaert, Raymond; Hilden, Sari Kristiina; Faraco, Vincenza; de Vries, Ronald (2018)
    Feruloyl esterases (FAEs) are a diverse group of enzymes that specifically catalyze the hydrolysis of ester bonds between a hydroxycinnamic (e.g. ferulic) acid and plant poly- or oligosaccharides. FAEs as auxiliary enzymes significantly assist xylanolytic and pectinolytic enzymes in gaining access to their site of action during biomass saccharification for biofuel and biochemical production. A limited number of FAEs have been functionally characterized compared to over 1000 putative fungal FAEs that were recently predicted by similarity-based genome mining, which divided phylogenetically into different subfamilies (SFs). In this study, 27 putative and six characterized FAEs from both ascomycete and basidiomycete fungi were selected and heterologously expressed in Pichia pastoris and the recombinant proteins biochemically characterized to validate the previous genome mining and phylogenetical grouping and to expand the information on activity of fungal FAEs. As a result, 20 enzymes were shown to possess FAE activity, being active towards pNP-ferulate and/or methyl hydroxycinnamate substrates, and covering 11 subfamilies. Most of the new FAEs showed activities comparable to those of previously characterized fungal FAEs.
  • Pöntinen, Anna; Aalto-Araneda, Mariella; Lindström, Miia; Korkeala, Hannu (2017)
    Listeria monocytogenes is one of the most heat-resistant non-sporeforming food-borne pathogens and poses a notable risk to food safety, particularly when mild heat treatments are used in food processing and preparation. While general heat stress properties and response mechanisms of L. monocytogenes have been described, accessory mechanisms providing particular L. monocytogenes strains with the advantage of enhanced heat resistance are unknown. Here, we report plasmidmediated heat resistance of L. monocytogenes for the first time. This resistance is mediated by the ATP-dependent protease ClpL. We tested the survival of two wildtype L. monocytogenes strains-both of serotype 1/2c, sequence type ST9, and high sequence identity-at high temperatures and compared their genome composition in order to identify genetic mechanisms involved in their heat survival phenotype. L. monocytogenes AT3E was more heat resistant (0.0 CFU/ml log(10) reduction) than strain AL4E (1.4 CFU/ml log(10) reduction) after heating at 55 degrees C for 40 min. A prominent difference in the genome compositions of the two strains was a 58-kb plasmid (pLM58) harbored by the heat-resistant AT3E strain, suggesting plasmid-mediated heat resistance. Indeed, plasmid curing resulted in significantly decreased heat resistance (1.1 CFU/ml log(10) reduction) at 55 degrees C. pLM58 harbored a 2,115-bp open reading frame annotated as an ATP-dependent protease (ClpL)-encoding clpL gene. Introducing the clpL gene into a natively heat-sensitive L. monocytogenes strain (1.2 CFU/ml log(10) reduction) significantly increased the heat resistance of the recipient strain (0.4 CFU/ml log(10) reduction) at 55 degrees C. Plasmid-borne ClpL is thus a potential predictor of elevated heat resistance in L. monocytogenes. IMPORTANCE Listeria monocytogenes is a dangerous food pathogen causing the severe illness listeriosis that has a high mortality rate in immunocompromised individuals. Although destroyed by pasteurization, L. monocytogenes is among the most heat-resistant non-spore-forming bacteria. This poses a risk to food safety, as listeriosis is commonly associated with ready-to-eat foods that are consumed without thorough heating. However, L. monocytogenes strains differ in their ability to survive high temperatures, and comprehensive understanding of the genetic mechanisms underlying these differences is still limited. Whole-genome-sequence analysis and phenotypic characterization allowed us to identify a novel plasmid, designated pLM58, and a plasmid-borne ATP-dependent protease (ClpL), which mediated heat resistance in L. monocytogenes. As the first report on plasmid-mediated heat resistance in L. monocytogenes, our study sheds light on the accessory genetic mechanisms rendering certain L. monocytogenes strains particularly capable of surviving high temperatures-with plasmid-borne ClpL being a potential predictor of elevated heat resistance.
  • Guo, Ming; Maltari, Riku; Zhang, Rui; Kontro, Jussi; Ma, Enlu; Repo, Timo (2021)
    Lignin is a potential renewable raw material for synthesis of aromatic molecules and materials. Particularly, Kraft-type lignins are abundantly available as a byproduct of wood and paper industries. Currently, there are practically no valuable products made using this highly complex polymer. Within this work, we have investigated the straightforward, high-yield depolymerization of two different technical lignins (Indulin AT and alkaline lignin) using only a mixture of green short-chain (C-1-C-3) alcohols and water as solvents. As shown here, at a temperature of 220 degrees C, autogenous pressure, and isopropanol/water as a co-solvent medium, it is possible to cleave Kraft lignin without char-forming side reactions. The obtained so-called "light" oil contains guaiacol-based monomeric units of 23 wt % yield together with liquid oligomers of 13 wt % yield combining liquid-liquid and solid-liquid extraction. Two-dimensional nuclear magnetic resonance analysis of lignin residues showed that the isopropanol/water treatment caused a marked breakdown of the intermolecular beta-O-4 and beta-beta bonds; thus, the depolymerization produced monomers and lignin residues with lower molecular weight. The results suggested a synergistic effect between isopropanol and water. No sign of repolymerization reactions could be observed with this process.
  • Sassetti, Elisa; Cruz, Cristina Durante; Tammela, Päivi; Winterhalter, Mathias; Augustyns, Koen; Gribbon, Philip; Windshügel, Björn (2019)
    The serine protease Caseinolytic protease subunit P (ClpP) plays an important role for protein homeostasis in bacteria and contributes to various developmental processes, as well as virulence. Therefore, ClpP is considered as a potential drug target in Gram-positive and Gram-negative bacteria. In this study, we utilized a biochemical assay to screen several small molecule libraries of approved and investigational drugs for Escherichia coli ClpP inhibitors. The approved drugs bortezomib, cefmetazole, cisplatin, as well as the investigational drug cDPCP, and the protease inhibitor 3,4-dichloroisocoumarin (3,4-DIC) emerged as ClpP inhibitors with IC50 values ranging between 0.04 and 31 mu M. Compound profiling of the inhibitors revealed cefmetazole and cisplatin not to inhibit the serine protease bovine -chymotrypsin, and for cefmetazole no cytotoxicity against three human cell lines was detected. Surface plasmon resonance studies demonstrated all novel ClpP inhibitors to bind covalently to ClpP. Investigation of the potential binding mode for cefmetazole using molecular docking suggested a dual covalent binding to Ser97 and Thr168. While only the antibiotic cefmetazole demonstrated an intrinsic antibacterial effect, cDPCP clearly delayed the bacterial growth recovery time upon chemically induced nitric oxide stress in a ClpP-dependent manner.
  • König, Walter; Konig, Emilia; Weiss, Kirsten; Tuomivirta, Tero T.; Fritze, Hannu; Elo, Kari; Vanhatalo, Aila; Jaakkola, Seija (2019)
    BACKGROUND Nitrite and hexamine are used as silage additives because of their adverse effects on Clostridia and Clostridia spores. The effect of sodium nitrite and sodium nitrite/hexamine mixtures on silage quality was investigated. A white lupin-wheat mixture was treated with sodium nitrite (NaHe0) (900 g t(-1) forage), or mixtures of sodium nitrite (900 g t(-1)) and hexamine. The application rate of hexamine was 300 g t(-1) (NaHe300) or 600 g t(-1) (NaHe600). Additional treatments were the untreated control (Con), and formic acid (FA) applied at a rate of 4 L t(-1) (1000 g kg(-1)). RESULTS Additives improved silage quality noticeably only by reducing silage ammonia content compared with the control. The addition of hexamine to a sodium nitrite solution did not improve silage quality compared with the solution containing sodium nitrite alone. The increasing addition of hexamine resulted in linearly rising pH values (P <0.001) and decreasing amounts of lactic acid (P <0.01). Sodium nitrite based additives were more effective than formic acid in preventing butyric acid formation. Additives did not restrict the growth of Saccharomyces cerevisiae compared to the control. CONCLUSION The addition of hexamine did not improve silage quality compared with a solution of sodium nitrite. (c) 2018 Society of Chemical Industry