Effect of Bis-Dimethylamine Substitution on DNA Binding Property and Cytotoxic Activity of Polyhydroxyxanthone.

A bis-dimethylamine substituted xanthone (Xan-2) was obtained by cationic modification of the free C3 and C6 hydroxy groups of 1,3,6-trihydroxyxanthone (Xan-1) which was isolated from Polygala hongkongensis Hemsl.. The results of the spectroscopic analysis, melting profiles, electrophoretic migration, PCR assay and molecular docking indicated that the hydrophobic plane of Xan-1 and Xan-2 could intercalate into the DNA base pairs meanwhile the basic amine alkyl chain of Xan-2 could bind with DNA phosphate framework via electrostatic interaction. Thus, Xan-2 exhibited higher DNA binding affinity than Xan-1. Further study showed that Xan-2 could inhibit the proliferation of HeLa, SGC-7901 and A549 cells effectively by MTT assay and induce apoptosis of HeLa cells as detected by AO/EB staining and flow cytometry assay. Interestingly, Xan-2 exhibited selective cytotoxicity to cells, which was proved by its relatively low inhibitory effect on Raw 264.7 cell. What these studies mean is that disubstituted amine alkyl chains will play an important role in DNA binding property and cytotoxic activity, providing a direction for the development of novel potential antitumor agents.

Double pH-sensitive nanotheranostics of polypeptide nanoparticle encapsulated BODIPY with both NIR activated fluorescence and enhanced photodynamic therapy.

To achieve accurate fluorescence imaging-guided cancer therapy, intelligent systems with specific responsiveness to the tumor microenvironment need to be designed. Here, we have achieved both enhanced NIR fluorescence and photodynamic therapy by introducing a dimethylamino functional group in BODIPY dyes, which can be used as a pH sensor under acidic conditions by coordinating with the proton. At pH 7.4, the fluorescence is quenched due to the photo-induced electron transfer (PET) process. After the photosensitizer is protonated in tumor cell lysosomes (pH 4.0-5.5), the PET process is inhibited and the fluorophore emission capacity is restored (fluorescence enhancement up to 10-fold), resulting in near-infrared fluorescence with the OFF/ON transition inside the tumor and enhanced singlet oxygen production for lysosome targeting capability. Due to the substitution of heavy atom iodine, the compound has a high singlet oxygen quantum yield of 81.8% in dichloromethane. In addition, using a pH-sensitive amphiphilic polypeptide (POEGMA23-PE9) as a carrier to wrap the photosensitizer BDPI can release enough drug in the acidic environment (pH 5.5-6.5) of intracellular endosomes/lysosomes, which is conducive to more adequate interactions of the photosensitizer with H+ and more effective enhancement of fluorescence emission and 1O2 production, achieving precise fluorescence imaging capability and extremely low background toxicity.

Dimethylamine enhances platelet hyperactivity in chronic kidney disease model.

Chronic kidney disease (CKD) remains a major health threat worldwide which is associated with elevated blood level of dimethylamine (DMA) and unbalanced platelet functions. Dimethylamine, a simple aliphatic amine, is abundantly found in human urine as well as other body fluids like plasma. However, the relation between dimethylamine and platelet activation is unclear. This study aims to unravel the mechanism of DMA and platelet function in chronic kidney disease. Through in vitro platelet characterization assay and in vivo CKD mouse model, the level of DMA, platelet activity and renal function were assessed by established methods. PKCδ and its downstream kinase MEK1/2 were examined by immunoblotting analysis of human platelet extract. Rescue experiments with PKCδ inhibitor or choline deficient diet were also conducted. DMA level in plasma of mouse CKD model was elevated along with enhanced platelet activation and comprised renal function. DMA can activate platelet in vitro and in vivo. Inhibition of PKCδ could antagonize the effect of DMA on platelet activation. When choline as the dietary source of DMA was deprived from CKD mouse, the level DMA was reduced and platelet activation was attenuated. Our results demonstrate that dimethylamine could enhance platelet activation in CKD model, potentially through activation of PKCδ.

Solvent-Free Fabrication of Self-Regenerating Antibacterial Surfaces Resisting Biofilm Formation.

Biofilm formation on indwelling medical devices is a major cause of hospital-acquired infections. Monofunctional antibacterial surfaces have been developed to resist the formation of biofilms by killing bacteria on contact, but the adsorption of killed bacterial cells and debris gradually undermines the function of these surfaces. Here, we report a facile approach to produce an antibacterial surface that can regenerate its function after contamination. The self-regenerating surface was achieved by sequential deposition of alternating antibacterial and biodegradable layers of coating using a solvent-free initiated chemical vapor deposition method. As the top antibacterial layer gradually loses its killing ability due to the accumulation of debris, the underlying biodegradable layer degrades, shedding off the top surface layers and exposing another fresh antibacterial surface. Urinary catheters coated with monofunctional and self-regenerating antibacterial coatings both showed more than 99% bacterial killing ability at the initial antibacterial test, but the monofunctional surface lost its killing ability after continued exposure to concentrated bacterial solution, whereas the self-regenerating surfaces regained strong bacterial killing ability after prolonged exposure. Employing poly(methacrylic anhydride) and its copolymers with varied composition as the degrading layer, the degradation kinetics can be well-tailored and the self-regeneration duration spanned from minutes to days. The designed self-regenerating antibacterial surfaces could provide an effective approach to resist biofilm formation and extend the service life of indwelling medical devices.

F-ATP-ase of Escherichia coli membranes: The ubiquitous MgADP-inhibited state and the inhibited state induced by the ε-subunit's C-terminal domain are mutually exclusive.

ATP synthases are important energy-coupling, rotary motor enzymes in all kingdoms of life. In all F-type ATP synthases, the central rotor of the catalytic F1 complex is composed of the γ subunit and the N-terminal domain (NTD) of the ε subunit. In the enzymes of diverse bacteria, the C-terminal domain of ε (εCTD) can undergo a dramatic conformational change to trap the enzyme in a transiently inactive state. This inhibitory mechanism is absent in the mitochondrial enzyme, so the εCTD could provide a means to selectively target ATP synthases of pathogenic bacteria for antibiotic development. For Escherichia coli and other bacterial model systems, it has been difficult to dissect the relationship between ε inhibition and a MgADP-inhibited state that is ubiquitous for FOF1 from bacteria and eukaryotes. A prior study with the isolated catalytic complex from E. coli, EcF1, showed that these two modes of inhibition are mutually exclusive, but it has long been known that interactions of F1 with the membrane-embedded FO complex modulate inhibition by the εCTD. Here, we study membranes containing EcFOF1 with wild-type ε, ε lacking the full εCTD, or ε with a small deletion at the C-terminus. By using compounds with distinct activating effects on F-ATP-ase activity, we confirm that εCTD inhibition and ubiquitous MgADP inhibition are mutually exclusive for membrane-bound E. coli F-ATP-ase. We determine that most of the enzyme complexes in wild-type membranes are in the ε-inhibited state (>50%) or in the MgADP-inhibited state (30%).

Injectable human recombinant collagen matrices limit adverse remodeling and improve cardiac function after myocardial infarction.

Despite the success of current therapies for acute myocardial infarction (MI), many patients still develop adverse cardiac remodeling and heart failure. With the growing prevalence of heart failure, a new therapy is needed that can prevent remodeling and support tissue repair. Herein, we report on injectable recombinant human collagen type I (rHCI) and type III (rHCIII) matrices for treating MI. Injecting rHCI or rHCIII matrices in mice during the late proliferative phase post-MI restores the myocardium's mechanical properties and reduces scar size, but only the rHCI matrix maintains remote wall thickness and prevents heart enlargement. rHCI treatment increases cardiomyocyte and capillary numbers in the border zone and the presence of pro-wound healing macrophages in the ischemic area, while reducing the overall recruitment of bone marrow monocytes. Our findings show functional recovery post-MI using rHCI by promoting a healing environment, cardiomyocyte survival, and less pathological remodeling of the myocardium.

Inhibition effects of pesticides on glutathione-S-transferase enzyme activity of Van Lake fish liver.

Glutathione-S-transferases (GSTs) have a function in xenobiotic metabolism. They are a significant multifunctional family with a wide variety of catalytic activities. In the current study, we determined in vitro inhibition effects of 2,4-dichlorophenoxyacetic acid dimethylamine salt (2,4-D DMA), haloxyfop-P-methyl, glyphosate isopropylamine, dichlorvos, and λ-cyhalothrin on purified GST. For this purpose, GST were purified from Van Lake fish (Chalcalburnus tarichii Pallas) liver with 29.25 EU mg-1 specific activity and 10.76% yield using GSH-agarose affinity chromatographic method. The pesticides were tested at various concentrations on in vitro GST activity. Ki constants were calculated as 0.17 ± 0.01, 0.25 ± 0.05, 3.72 ± 0.32, 0.42 ± 0.06, and 0.025 ± 0.004 mM, for 2,4-D DMA, haloxyfop-P-methyl, glyphosate isopropylamine, dichlorvos, and λ-cyhalothrin, respectively. λ-Cyhalothrin showed a better inhibitory effect compared to the other pesticides. The inhibition mechanisms of λ-cyhalothrin were competitive, while the other pesticides were noncompetitive.

Antimalarial effect of two photo-excitable compounds in a murine model with Plasmodium berghei (Haemosporida: Plasmodiidae) / Efecto antimalárico de dos compuestos foto-excitables en un modelo murino con Plasmodium berghei (Haemosporida: Plasmodiidae)

Abstract Malaria represents a major health problem worldwide, affecting around 198 million people in 2016 according to WHO database. For decades, anti-malarial drug therapy has been used in the battle against this disease and its uncontrolled usage in endemic areas has developed the appearance of the drug resistance. Thus, it has emerged the necessity of finding new treatments that could be used as an alternative cure to malaria infection. The aim of this work was the evaluation of two photo-excitable compounds: Compound 1, which is (2E)-3-(4-dimethylamino-phenyl)-1-(4-imidazol-1-yl-phenyl)prop-2-en-1-one) and Compound 2, (1E,4E)1-[4-(dimethylamino)phenyl]-5-(4-methoxyphenyl)-1,4-pentadiene-3-one) as possible anti-malaria drugs with Plasmodium berghei ANKA strain in BALB/c mice as murine model. Cytotoxicity effect was evaluated by a cell proliferation by colorimetry assay (MTS); and the drug incorporation into the parasite was assessed in vitro with Indirect Immunofluorescence Assay (IFA) to determine the localization of the drugs into the parasitized red blood cells (RBCs). Finally, the curative effect of compounds no-radiation (fundamental state) and ration drugs were evaluated by oral drug administration of this drugs in BALB/c mice and chloroquine was used as positive control. This curative effect was determined daily by the parasitemia percentage. The results showed that both compounds were cytotoxic in fundamental state. Furthermore, cytotoxic effect was increased after radiation into the Solar Simulator, and compound 2 was more cytotoxic than compound 1. Curative assays showed that both compounds in fundamental state were non effective as anti-malarial drug. However, in the curative assays in the mice treated with compound 2, when this was ration showed a survival rate of 33 % and a parasitemia percentage decrease in compare to compound 1. Although the compounds did not show a similar or better anti-malarial effect than Chloroquine, Compound 2 presented certain anti-malarial effect after solar radiation. Rev. Biol. Trop. 66(2): 880-891. Epub 2018 June 01.

Resumen La malaria representa un importante problema de salud en todo el mundo, afectando a alrededor de 198 millones de personas en 2016 según la base de datos de la OMS. Durante décadas, se ha utilizado la terapia con fármacos anti-malpricos en la lucha contra esta enfermedad y su uso incontrolado en las zonas endémicas ha desarrollado la aparición de resistencia a los fármacos. Por lo tanto, se ha surgido la necesidad de encontrar nuevos tratamientos que podrían ser utilizados como una cura alternativa para la infección por el paludismo. El objetivo de este trabajo fue evaluar dos compuestos foto-excitables: El compuesto 1, que es (2E) -3- (4-dimetilamino-fenil) -1- (4-imidazol-1-ilfenil) prop-2 1-ona) y el Compuesto 2, (1E, 4E) -1- [4- (dimetilamino) fenil] -5- (4-metoxifenil) -1,4-pentadieno-3-ona) como posibles drogas antimaláricas con la cepa ANKA de Plasmodium berghei en ratones BALB / c como modelo murino. El efecto de la citotoxicidad se evaluó mediante una proliferación celular con el ensayo de colorimetría (MTS); y la incorporación del fármaco en el parásito se evaluó in vitro con Ensayo de Inmunofluorescencia Indirecta (IFA) para determinar la localización de los fármacos en los glóbulos rojos parasitados (RBCs). Finalmente, se evaluó el efecto curativo de los compuestos sin radiación (estado fundamental) y los fármacos irradiados mediante la administración oral de los fármacos en los ratones BALB / c, y se usó cloroquina como control positivo de cura. Este efecto curativo se determinó diariamente por el porcentaje de parasitemia. Los resultados mostraron que ambos compuestos eran citotóxicos en estado fundamental. Además, el efecto citotóxico se incrementó después de la radiación en el Simulador Solar, y el compuesto 2 fue más citotóxico que el compuesto 1. Los ensayos curativos mostraron que ambos compuestos en estado fundamental no eran eficaces como fármacos antimaláricos. Sin embargo, en los ensayos curativos en los ratones tratados con el compuesto 2, cuando fue irradiado, se observó una tasa de supervivencia del 33 % y una disminución del porcentaje de parasitemia en comparación con el compuesto 1. Aunque los compuestos no mostraron un efecto similar o mejor antimalárico que la cloroquina, el compuesto 2 presentó cierto efecto antimalárico después de la radiación solar.

Structure-activity relationship investigation of benzamide and picolinamide derivatives containing dimethylamine side chain as acetylcholinesterase inhibitors.

A series of benzamide and picolinamide derivatives containing dimethylamine side chain (4a-4c and 7a-7i) were synthesised and evaluated for acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitory activity in vitro. Structure-activity relationship investigation revealed that the substituted position of dimethylamine side chain markedly influenced the inhibitory activity and selectivity against AChE and BChE. In addition, it seemed that the bioactivity of picolinamide amide derivatives was stronger than that of benzamide derivatives. Among them, compound 7a revealed the most potent AChE inhibitory activity (IC50: 2.49 ± 0.19 µM) and the highest selectivity against AChE over BChE (Ratio: 99.40). Enzyme kinetic study indicated that compound 7a show a mixed-type inhibition against AChE. The molecular docking study revealed that this compound can bind with both the catalytic site and the peripheral site of AChE.

Evaluation of eco-friendly zwitterionic detergents for enveloped virus inactivation.

Inclusion of a detergent in protein biotherapeutic purification processes is a simple and very robust method for inactivating enveloped viruses. The detergent Triton X-100 has been used for many years and is part of the production process of several commercial therapeutic proteins. However, recent ecological studies have suggested that Triton X-100 and its break-down products can potentially behave as endocrine disrupters in aquatic organisms, raising concerns from an environmental impact perspective. As such, discharge of Triton X-100 into the waste water treatment plants is regulated in some jurisdictions, and alternative detergents for viral inactivation are required. In this work, we report on the identification and evaluation of more eco-friendly detergents as viable replacements for Triton X-100. Five detergent candidates with low to moderate environmental impact were initially identified and evaluated with respect to protein stability, followed by proof-of-concept virus inactivation studies using a model enveloped virus. From the set of candidates lauryldimethylamine N-oxide (LDAO) was identified as the most promising detergent due to its low ecotoxicity, robust anti-viral activity (LRV >4 at validation set-point conditions with X-MuLX), and absence of any negative impact on protein function. This detergent exhibited effective and robust virus inactivation in a broad range of protein concentrations, solution conductivities, pHs, and in several different cell culture fluid matrices. The only process parameter which correlated with reduced virus inactivation potency was LDAO concentration, and then only when the concentration was reduced to below the detergent's critical micelle concentration (CMC). Additionally, this work also demonstrated that LDAO was cleared to below detectable levels after Protein A affinity chromatography, making it suitable for use in a platform process that utilizes this chromatographic mode for protein capture. All these findings suggest that LDAO may be a practical alternative to Triton X-100 for use in protein therapeutic production processes for inactivating enveloped viruses. Biotechnol. Bioeng. 2017;114: 813-820. © 2016 Wiley Periodicals, Inc.

Recurrent selection with reduced 2,4-D amine doses results in the rapid evolution of 2,4-D herbicide resistance in wild radish (Raphanus raphanistrum L.).

BACKGROUND: When used at effective doses, weed resistance to auxinic herbicides has been slow to evolve when compared with other modes of action. Here we report the evolutionary response of a herbicide-susceptible population of wild radish (Raphanus raphanistrum L.) and confirm that sublethal doses of 2,4-dichlorophenoxyacetic acid (2,4-D) amine can lead to the rapid evolution of 2,4-D resistance and cross-resistance to acetolactate synthase (ALS)-inhibiting herbicides. RESULTS: Following four generations of 2,4-D selection, the progeny of a herbicide-susceptible wild radish population evolved 2,4-D resistance, increasing the LD50 from 16 to 138 g ha-1 . Along with 2,4-D resistance, cross-resistance to the ALS-inhibiting herbicides metosulam (4.0-fold) and chlorsulfuron (4.5-fold) was evident. Pretreatment of the 2,4-D-selected population with the cytochrome P450 inhibitor malathion restored chlorsulfuron to full efficacy, indicating that cross-resistance to chlorsulfuron was likely due to P450-catalysed enhanced rates of herbicide metabolism. CONCLUSION: This study is the first to confirm the rapid evolution of auxinic herbicide resistance through the use of low doses of 2,4-D and serves as a reminder that 2,4-D must always be used at highly effective doses. With the introduction of transgenic auxinic-herbicide-resistant crops in the Americas, there will be a marked increase in auxinic herbicide use and therefore the risk of resistance evolution. Auxinic herbicides should be used only at effective doses and with diversity if resistance is to remain a minimal issue. © 2016 Society of Chemical Industry.

Impacts of epichlorohydrin-dimethylamine on coagulation performance and membrane fouling in coagulation/ultrafiltration combined process with different Al-based coagulants.

Two kinds of aluminum-based coagulants and epichlorohydrin-dimethylamine (DAM-ECH) were used in the treatment of humic acid-kaolin simulated water by coagulation-ultrafiltration (C-UF) hybrid process. Coagulation performance, floc characteristics, including floc size, compact degree, and strength were investigated in this study. Ultrafiltration experiments were conducted by a dead-end batch unit to implement the resistance analyses to explore the membrane fouling mechanisms. Results showed that DAM-ECH aid significantly increased the UV254 and DOC removal efficiencies and contributed to the formation of larger and stronger flocs with a looser structure. Aluminum chloride (Al) gave rise to better coagulation performance with DAM-ECH compared with poly aluminum chloride (PACl). The consequences of ultrafiltration experiments showed that DAM-ECH aid could reduce the membrane fouling mainly by decreasing the cake layer resistance. The flux reductions for PACl, Al/DAM-ECH (dosing both Al and DAM-ECH) and PACl/DAM-ECH (dosing both PACl and DAM-ECH) were 62%, 56% and 44%, respectively. Results of this study would be beneficial for the application of PACl/DAM-ECH and Al/DAM-ECH composite coagulants in water treatment processes.

Exploratory Biomarker Study of the Triple Reuptake Inhibitor SEP-432 Compared to the Dual Reuptake Inhibitor Duloxetine in Healthy Normal Subjects.

INTRODUCTION: SEP-432 is a triple monoamine reuptake inhibitor of norepinephrine (NE), serotonin (5-HT), and dopamine (DA), based on in vitro binding studies. We sought evidence that SEP-432 engages these monoamine systems by measuring concentrations of monoamines and/or their main metabolites in cerebrospinal fluid (CSF) and plasma and comparing results to duloxetine, a dual reuptake inhibitor of NE and 5-HT. METHODS: Eighteen healthy normal subjects received either SEP-432 (300 mg/day), duloxetine (60 mg/day), or placebo for 14 days in-clinic (double blind) with CSF and plasma collections at baseline (single lumbar puncture) and Day 14 (24-h CSF and plasma collection). Concentrations of monoamines and their metabolites, as well as pharmacokinetic concentrations of SEP-432 and metabolite, were quantified by liquid chromatography-tandem mass spectrometry. RESULTS: Compared to placebo in the Day 14 area under the curve 24-h (AUC0-24 h ) analysis, SEP-432 significantly (P < 0.05) decreased the NE metabolite dihydroxyphenylglycol (DHPG) in CSF and plasma, decreased 5-HT in plasma, and did not affect DA metabolites, while duloxetine had significant effects on DHPG and 5-HT. Time-matched baseline to Day 14 biomarker comparisons confirmed these findings. CONCLUSION: CSF monoamine biomarkers confirmed central NET activity for SEP-432 and duloxetine's dual reuptake inhibition.

Synthesis and antiproliferative activity of 2,7-diamino l0-(3,5-dimethoxy)benzyl-9(10H)-acridone derivatives as potent telomeric G-quadruplex DNA ligands.

A novel series of l0-(3,5-dimethoxy)benzyl-9(10H)-acridone derivatives with terminal ammonium substituents at C2 and C7 positions on the acridone ring were successfully synthesized as antiproliferation agents. The biologic activity of the acridone compounds against leukemia CCRF-CEM cells demonstrated that some of the compounds displayed good antiproliferative activity, among which compound 6a containing dimethylamine substituents at the terminal C2 and C7 positions exhibited the highest cytotoxicity with IC50 at 0.3µM. In addition compound 6a showed little toxicity against normal 293T cells proliferation with IC50 more than 100µM. Further study indicated that compound 6a had strong binding activity to human telomeric G-quadruplex DNA, as detected by mass spectrometry, CD spectroscopy, UV absorption, FRET and fluorescence quenching assays. Our data suggested that the activity of 6a might be associated with its stabilization of G-quadruplex DNA, which can be developed as potent antitumor agent.

The human ether-a'-go-go related gene (hERG) K+ channel blockade by the investigative selective-serotonin reuptake inhibitor CONA-437: limited dependence on S6 aromatic residues.

Diverse non-cardiac drugs adversely influence cardiac electrophysiology by inhibiting repolarising K(+) currents mediated by channels encoded by the human ether-a-go-go-related gene (hERG). In this study, pharmacological blockade of hERG K(+) channel current (I(hERG)) by a novel investigative serotonin-selective reuptake inhibitor (SSRI), CONA-437, was investigated. Whole-cell patch-clamp measurements of I(hERG) were made from human embryonic kidney (HEK 293) cells expressing wild-type (WT) or mutant forms of the hERG channel. With a step-ramp voltage-command, peak I(hERG) was inhibited with an IC(50) of 1.34 µM at 35 ±1°C; the IC(50) with the same protocol was not significantly different at room temperature. Voltage-command waveform selection had only a modest effect on the potency of I(hERG) block: the IC50 with a ventricular action potential command was 0.72 µM. I(hERG) blockade developed rapidly with time following membrane depolarisation and showed a weak dependence on voltage, accompanied by a shift of ≈ -5 mV in voltage-dependence of activation. There was no significant effect of CONA-437 on voltage-dependence of I(hERG) inactivation, though at some voltages an apparent acceleration of the time-course of inactivation was observed. Significantly, mutation of the S6 aromatic amino acid residues Y652 and F656 had only a modest effect on I(hERG) blockade by CONA-437 (a 3-4 fold shift in affinity). CONA-437 at up to 30 µM had no significant effect on either Nav1.5 sodium channels or L-type calcium channels. In conclusion, the novel SSRI CONA-437 is particularly notable as a gating-dependent hERG channel inhibitor for which neither S6 aromatic amino-acid constituent of the canonical drug binding site on the hERG channel appears obligatory for I(hERG) inhibition to occur.

Effects of N,N-dimethyl-N-alkylamine-N-oxides on DOPC bilayers in unilamellar vesicles: small-angle neutron scattering study.

Small-angle neutron scattering data were collected from aqueous dispersions of unilamellar vesicles (ULVs) consisting of mixtures of 1,2-dioleoyl-sn-glycero-3-phosphatidylcholine and a homologous series of N,N-dimethyl-N-alkylamine-N-oxides (CnNO, n = 12, 14, 16, and 18, where n is the number of carbon atoms in the alkyl chain). A modeling approach was applied to the neutron scattering curves to obtain the bilayer structural parameters. Particularly, the external (2)H2O/H2O contrast variation technique was carried out on pure dioleoylphosphatidylcholine (DOPC) ULVs to determine the hydrophilic region thickness [Formula: see text] = 9.8 ± 0.6 Å. Consequently, the hydrocarbon region thickness [Formula: see text], the lateral bilayer area per one lipid molecule [Formula: see text], and the number of water molecules located in the hydrophilic region per one lipid molecule [Formula: see text] were obtained from single-contrast neutron scattering curves using the previously determined [Formula: see text]. The structural parameters were extracted as functions of [Formula: see text] (the CnNO:DOPC molar ratio) and n. The dependences [Formula: see text] provided the partial lateral areas of CnNOs ([Formula: see text]) and DOPC ([Formula: see text]) in bilayers. It was observed that the [Formula: see text]'s were constant in the investigated interval of [Formula: see text] and for n = 12, 14, and 16 equal to 36.6 ± 0.4 Å(2), while [Formula: see text] increased to 39.4 ± 0.4 Å(2). The bilayer hydrocarbon region thickness [Formula: see text] decreased with intercalation of each CnNO. This effect increased with [Formula: see text] and decreased with increasing CnNO alkyl chain length. The intercalation of C18NO changed the [Formula: see text] only slightly. To quantify the effect of CnNO intercalation into DOPC bilayers we fit the [Formula: see text] dependences with weighted linear approximations and acquired their slopes [Formula: see text].

Design, synthesis and evaluation of novel 4-dimethylamine flavonoid derivatives as potential multi-functional anti-Alzheimer agents.

A series of 4-dimethylamine flavonoid derivatives 5a-5r were designed, synthesized and evaluated as potential multi-functional anti-Alzheimer agents. The results showed that most of the synthesized compounds exhibited high acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitory activity at the micromolar range (IC50, 1.83-33.20 µM for AChE and 0.82-11.45 µM for BChE). A Lineweaver-Burk plot indicated a mixed-type inhibition for compound 5j with AChE, and molecular modeling study showed that 5j targeted both the catalytic active site (CAS) and the peripheral anionic site (PAS) of AChE. Besides, the derivatives showed potent self-induced Aß aggregation inhibitory activity at 20 µM with percentage from 25% to 48%. In addition, some compounds (5j-5q) showed potent oxygen radical absorbance capacity (ORAC) ranging from 1.5- to 2.6-fold of the Trolox value. These compounds should be further investigated as multi-potent agents for the treatment of Alzheimer's disease.

Syntheses and structures of new trimetallic complexes bridged by N-(5-chloro-2-hydroxyphenyl)-N'-[3-(dimethylamino)propyl]oxamide: cytotoxic activities, and reactivities towards DNA and protein.

Two new µ-oxamido-bridged trinuclear complexes, namely [Cu(3)L(2)(H(2)O)(2)]{[Cu(3)L(2)]·2H(2)O}(2) (1) and [Ni(3)L(2)(H(2)O)(DMF)](H(2)O)(DMF) (2), where L(3-) is deprotonated N-(5-chloro-2-hydroxyphenyl)-N'-[3-(dimethylamino)propyl]oxamide, have been synthesized and characterized by X-ray single-crystal diffraction. The structure of complex 1, which consists of three tricopper(II) neutral molecules, lies on an inversion centre at Cu5 atom and thus has a trans conformation. The structure of complex 2 composes of a trinickel(II) neutral molecule. In vitro cytotoxic activities, and the reactivities of the two complexes towards DNA and protein are investigated. Cytotoxicities experiments reveal that the two trinuclear complexes both exhibits cytotoxic effects against human hepatocellular carcinoma cell SMMC-7721 and human lung adenocarcinoma cell A549. The interactions of the two complexes with herring sperm DNA (HS-DNA) are investigated by using UV absorption and fluorescence spectra and viscometry. The results suggested that both of the two trinuclear complexes could interact with HS-DNA through the intercalation mode and follow the binding affinity order of 1>2. The reactivity towards protein BSA revealed that the quenching of BSA fluorescence by the two complexes are static quenching, and complex 1 exhibits a higher BSA-binding ability than that of complex 2.

Mass spectrometric O-glycan analysis after combined O-glycan release by beta-elimination and 1-phenyl-3-methyl-5-pyrazolone labeling.

BACKGROUND: Analysis of protein glycosylation is an important first step towards establishing the functions of glycans in health and disease. In contrast to N-glycans which are generally enzymatically released for analysis, there is no corresponding enzyme for O-glycan liberation. Therefore, O-glycans are generally released by chemical methods involving tedious procedures. METHODS: Here, a straightforward method for the combined release and labeling of O-linked glycans from glycoproteins is described. Dimethylamine serves as the releasing agent, and 1-phenyl-3-methyl-5-pyrazolone (PMP) is employed for a prompt reaction with the reducing end of the freshly released O-glycan structures via an aldol condensation followed by a Michael-type addition resulting in a 2:1 stoichiometry of PMP per glycan. Samples are analyzed by nanoLC coupled to mass spectrometry. RESULTS: Mucin from bovine submaxillary gland was used as a model protein to evaluate and optimize the approach that was further applied to bile salt stimulated lipase (BSSL) isolated from human milk. Next to previously reported O-glycan structures two additional oligosaccharides could be detected for BSSL. GENERAL SIGNIFICANCE: In conclusion, the facile protocol established is suitable for the analysis of complex O-linked oligosaccharides from various biological samples. This article is part of a Special Issue entitled Glycoproteomics.

Probing the topography of the photosystem II oxygen evolving complex: PsbO is required for efficient calcium protection of the manganese cluster against dark-inhibition by an artificial reductant.

The photosystem II (PSII) manganese-stabilizing protein (PsbO) is known to be the essential PSII extrinsic subunit for stabilization and retention of the Mn and Cl(-) cofactors in the oxygen evolving complex (OEC) of PSII, but its function relative to Ca(2+) is less clear. To obtain a better insight into the relationship, if any, between PsbO and Ca(2+) binding in the OEC, samples with altered PsbO-PSII binding properties were probed for their potential to promote the ability of Ca(2+) to protect the Mn cluster against dark-inhibition by an exogenous artificial reductant, N,N-dimethylhydroxylamine. In the absence of the PsbP and PsbQ extrinsic subunits, Ca(2+) and its surrogates (Sr(2+), Cd(2+)) shield Mn atoms from inhibitory reduction (Kuntzleman et al., Phys Chem Chem Phys 6:4897, 2004). The results presented here show that PsbO exhibits a positive effect on Ca(2+) binding in the OEC by facilitating the ability of the metal to prevent inhibition of activity by the reductant. The data presented here suggest that PsbO may have a role in the formation of the OEC-associated Ca(2+) binding site by promoting the equilibrium between bound and free Ca(2+) that favors the bound metal.