Fenton-like reaction of the iron(II)-histidine complex generates hydroxyl radicals: implications for oxidative stress and Alzheimer's disease.

The hydroxyl radical (˙OH), generated from Fenton/Fenton-like reactions of iron(II) species in biology, can oxidatively damage biomolecules, inducing oxidative stress and diseases. However, this common understanding has been questioned recently after a carbonate radical was observed from the Fenton-like reaction of the iron(II)-carbonate complex. Herein, we report that the Fenton-like reaction of the iron(II)-histidine complex, one major iron(II) species in blood plasma, can occur at neutral pH to generate ˙OH, not iron(IV). Our findings and critical analyses on relevant studies clarify the above doubt, reveal a new pathway of causing oxidative stress by the iron(II) species, and have implications for Alzheimer's disease.

Protein molecular defect detection method based on a neural network algorithm.

Proteins, as the largest macromolecules in the body, are among the most important components of the body and play very vital and important roles. These substances are made up of a series of amino acid chains that, depending on the type of protein, the number of these amino acids can reach several thousand. Proteins function differently depending on the type and location of their presence, including enzymatic activity to catalyze the process, identify microbes and cancer cells, transport substances such as respiratory gases, and signalize. In the biochemical experiment, the problem of optimizing the detection of protein molecular defects, because of the randomness of the information, parameters, selection and setting, limits the detection accuracy of protein molecular defects. Based on the characteristics of fast learning speed and a robust network of neural network algorithm, a protein molecular defect detection method based on a neural network algorithm was proposed. Firstly, the protein secondary structure was predicted by the method of protein secondary structure prediction based on the generalized regression neural network to obtain the protein structural features; secondly, the protein defective molecular sequence classification model based on the neural network was used to classify the protein defective molecular sequence to achieve the protein molecular defect detection. The results showed that the detection accuracy of the proposed method was very high, which meets the needs of protein molecular defect detection, and has some application advantages compared with similar detection methods.

Nutrients removal from piggery wastewater coupled to lipid production by a newly isolated self-flocculating microalga Desmodesmus sp. PW1.

A newly isolated microalgal strain, Desmodesmus sp. PW1, possessing not only high potential for removing nitrogen and phosphorous from piggery wastewater but excellent self-flocculating ability, was provided here. Strain PW1 grew well in diluted and undiluted piggery wastewater, and could effectively remove total nitrogen and total phosphorus with removal rates up to 90% and 70%, respectively. In the laboratory scale by 30-L photobioreactor, microalga also performed well in TN (65.3%) and TP (83.5%) removal. Strain PW1 cultivated in the stationary phase achieved high self-flocculating efficiency (>90%) in 2.5 h of settling; meanwhile, temperature and pH slightly influenced on the flocculation. The potential mechanism on self-flocculation was considered related to hydrophobic extracellular polymeric substances. Furthermore, the fatty acid compositions of PW1 were mainly hexadecanoic acid, oleic acid and linoleic acid. Taken together, Desmodesmus sp. PW1 was the promising candidate to overcome the microalgae harvesting problem in piggery wastewater treatment.

Detection and identification of the oxidizing species generated from the physiologically important Fenton-like reaction of iron(II)-citrate with hydrogen peroxide.

The Fenton-like reaction of iron(II)-citrate with hydrogen peroxide is physiologically important because it is associated with the oxidative stress and pathological processes induced by the redox-active iron pool in vivo. However, the oxidizing species generated from this reaction at neutral pH has not been convincingly identified because two extremely unstable and hard-to-differentiate species, the hydroxyl radical (•OH) and iron(IV) (ferryl) species, can be produced. Identifying this species is essential for understanding the reaction mechanism. Although there were few data that reported the detection of •OH from this reaction by using the EPR and fluorescence techniques, most of these data were obtained without the necessary assessment with a •OH scavenger. Furthermore, these two techniques may not be able to differentiate the •OH and iron(IV) species. Thus, these reported data cannot lead to a convincing conclusion that the •OH, not the iron(IV) species, was generated. Therefore, in the study reported herein, we carried out systematic investigations first by using the EPR and fluorescence techniques combined with a •OH scavenger to detect the oxidizing species generated from this Fenton-like reaction. Then we utilized NMR spectroscopy and for the first time obtained convincing evidence to demonstrate that this oxidizing species is the •OH rather than iron(IV) species. We also determined the second-order rate constant of the reaction, 3.6 × 103 M-1s-1 (pH7.0, 25 °C), by using the stopped-flow spectrophotometry. On the basis of these findings, a scheme is proposed for the mechanism of this physiologically important Fenton-like reaction.

Docking based design of diastereoisomeric MTCA as GPIIb/IIIa receptor inhibitor.

In GPIIb/IIIa mediated arterial thrombosis platelet activation plays a central role. To discover platelet activation inhibitor the pharmacophores of GPIIb/IIIa receptor inhibitors and anti-thrombotic agents were analyzed. This led to the design of (1R,3S)- and (1S,3S)-1-methyl-1,2,3,4-tetrahydro-ß-carboline-3-carboxylic acids as GPIIb/IIIa inhibitors. Comparing to (1S,3S)-isomer (1R,3S)-isomer had lower cdocker interaction energy. AFM image showed that the minimal effective concentration of (1S,3S)-isomer and (1R,3S)-isomer inhibiting platelet activation were 10-5 M and 10-6 M, respectively. In vivo 1 µmol/kg of oral (1S,3S)-isomer effectively inhibited the rats to form arterial thrombus and down regulated GPIIb/IIIa expression, but the activities were significantly lower than those of 1 µmol/kg of oral (1R,3S)-isomer. Both (1S,3S)-isomer and (1R,3S)-isomer can be safely used for structural modifications, but (1R,3S)-isomer should be superior to (1S,3S)-isomer.

The nitroxide Tempo inhibits hydroxyl radical production from the Fenton-like reaction of iron(II)-citrate with hydrogen peroxide.

In vivo physiological ligand citrate can bind iron(II) ions to form the iron(II)-citrate complex. Inhibition of hydroxyl radical (OH) production from the Fenton-like reaction of iron(II)-citrate with H2O2 is biologically important, as this reaction may account for one of the mechanisms of the labile iron pool in vivo to induce oxidative stress and pathological conditions. Nitroxides have promising potentials as therapeutic antioxidants. However, there are controversial findings indicating that they not only act as antioxidants but also as pro-oxidants when engaged in Fenton reactions. Although the underlying mechanisms are proposed to be the inhibition or enhancement of the OH production by nitroxides, the proposed elucidations are only based on assessing biological damages and not demonstrated directly by measuring the OH production in the presence of nitroxides. In this study, therefore, we employed EPR and fluorescence spectroscopies to show direct evidence that nitroxide 2,2,6,6-tetramethyl-piperidine-1-oxyl (Tempo) inhibited OH production from the Fenton-like reaction of iron(II)-citrate with H2O2 by up to 90%. We also demonstrated spectrophotometrically, for the first time, that this inhibition was due to oxidation of the iron(II)-citrate by Tempo with a stoichiometry of Tempo:Iron(III)-citrate = 1.1:1.0. A scheme was proposed to illustrate the roles of nitroxides engaged in Fenton/Fenton-like reactions.

Tunable Supramolecular Hexagonal Columnar Structures of Hydrogen-Bonded Copolymers Containing Two Different Sized Dendritic Side Chains.

Polymer structures with tunable symmetry and sizes are desired for applications such as lithography, filtration membranes, and separation. Here we report the self-assembled supramolecular hexagonal columnar (ΦH) structures with tunable lattice size varying from 5 to 7 nm by constructing hydrogen-bonded copolymers bearing poly(4-vinylpyridine) (P4VP) and two dendritic molecular additives, 1-[4'-(3″,4″,5″-tridecyloxybenzoyloxy)phenyleneoxycarbonyl]-3-[(4″-hydroxyphenyl)oxycarbonyl]benzene (12CBP) and 4-hydroxyphenyl (3,4,5-tridecyloxy)benzoate (12CTB). Despite the distinct molecular size difference between 12CBP and 12CTB, the resulting ternary supramolecular copolymers, P4VP(12CBP)x(12CTB)y, possess a homogeneous ΦH phase at x ≥ 0.1 and y ≥ 0.2. Each column is constructed with P4VP as the backbone tethered with mixed side chains. The column diameter is between the size of the corresponding P4VP(12CBP)x+y and P4VP(12CTB)x+y and could be easily tuned by varying x and y. The enhancement of ΦH in supramolecular copolymers is attributed to the entropy effect of the mixed side chain and enthalpy effect from hydrogen bonding interaction of the P4VP backbone and two molecules (12CBP and 12CTB).

Safety of femtosecond laser-assisted cataract surgery: assessment of aqueous humour and lens capsule.

PURPOSE: To investigate the effect of femtosecond laser-assisted cataract surgery (FLACS) on aqueous humour and lens capsule. METHODS: This prospective randomized comparative study enrolled 19 eyes that underwent FLACS as the trial group and 20 eyes that underwent conventional phacoemulsification as the control group. The femtosecond laser platform (LLS-fs 3D; LensAR, Orlando, FL, USA) was used to generate capsulotomy (laser energy 8 µJ) and lens fragmentation (laser energy 10 µJ). Morphology of the cutting edge and cells of anterior capsule was assessed by light microscopy. The proteins in the aqueous humour were identified by mass spectrometry (Ultraflex III TOF/TOF; Bruker Dalton, Bremen, Germany). Electrolyte in the aqueous humour was detected by a chemistry analyzer (Aeroset Clinical Chemistry Analyzer; Abbott Laboratories, Abbott Park, IL, USA). RESULTS: The cutting edge of anterior capsule was saw-tooth-shaped under magnification of 200× and 400× in the trial group, while it was smooth in the control group. Intact cells were found in the boundary area next to the cutting edge of anterior capsule in both groups. ß-Crystallin B1, γ-crystallin S and transferrin were detected in the aqueous humour in the trial group. The concentrations of K+ , Na+ and Cl- in the aqueous humour in the trial group differed significantly from those in the control group (p = 0.02, 0.03 and 0.04, respectively). CONCLUSION: Femtosecond laser-assisted cataract surgery (FLACS) causes release of transferrin and crystallin from lens to aqueous humour and results in significant changes in the concentrations of K+ , Na+ and Cl- in aqueous humour. However, these changes due to FLACS have no clinical significance or toxicity.

Oximated ruthenium tris-bipyridyl complex: synthesis and luminescent response specifically for ClO(-) in water containing multiple ions.

Hypochlorite has been widely and essentially used as the disinfecting agent of water in our daily life. Rapidly, specifically, quantitatively and simply monitoring ClO(-) in water remains to be investigated and is of importance. For this purpose a novel complex bis(2,2'-bipyridine)(4'-methyl-2,2'-bipyridyl-4-carbaldehyde oxime)ruthenium chloride (Ru-C[double bond, length as m-dash]N-OH) was prepared. In water, reaction of complex Ru-C[double bond, length as m-dash]N-OH and ClO(-) results in bis(2,2'-bipyridine)(4'-methyl-2,2'-bipyridyl-4-carboxylic acid)ruthenium (Ru-CO2H) and thereby offers an efficient luminescence response. This was ascertained to be a specific oxidation reaction of complex Ru-C[double bond, length as m-dash]N-OH with ClO(-), and can be used for quantitatively monitoring aqueous ClO(-). The product of the oxidation reaction of complex Ru-C[double bond, length as m-dash]N-OH and ClO(-) was isolated and assigned to Ru-CO2H. The luminescent emission spectra of complex Ru-C[double bond, length as m-dash]N-OH in the presence of ClO(-) demonstrated that the coexistence of F(-), Cl(-), Br(-), I(-), HCO3(-), HSO4(-), H2PO4(-), S2O3(2-), SO3(2-), CO3(2-), PO4(3-), HPO4(2-), NO3(-), AcO(-), Li(+), Na(+), K(+), Ca(2+), Mg(2+), Zn(2+), Co(2+), Fe(3+), Ni(2+), Pb(2+), Hg(2+), Mn(2+) and Cu(2+) did not interfere in the quantitative change of the intensity of the luminescent emission.

An efficient ruthenium tris(bipyridine)-based luminescent chemosensor for recognition of Cu(II) and sulfide anion in water.

A novel efficient luminescent chemosensor based on a 1,4,7,10-tetraazacyclododecane (cyclen)-tethered Ru(bpy)3(2+) derivative (Ru-cyclen) has been synthesized and characterized. It displays an ON-OFF-type luminescence change with excellent selectivity towards Cu(II) amongst 16 metal ions in 100% aqueous solution. The binding stoichiometry of Ru-cyclen with Cu(2+) was established by Job plot analysis and mass spectral evidence. Furthermore, the in situ generated Ru-cyclen-Cu ensemble recovered luminescence in the presence of S(2-), indicating an 'OFF-ON'-type sensing process. Similar phenomena were not observed with other common anions and biothiols, making it a high selective sulfide probe. Finally, the sensing mechanism is confirmed to be displacement approach by NMR, mass and emission spectrometry.

The application of tetrahydroisoquinoline-3-carbonyl-TARGD(F)F as an anti-thrombotic agent having dual mechanisms of action.

Platelet surface glycoproteins P-selectin and GPIIb/IIIa are implicated in the formation of platelet-fibrin-leukocyte thrombus and platelet-fibrin-platelet thrombus, respectively. In the current study, taking N-(3S-tetrahydroisoquinoline-3-carbonyl)-Thr-Ala-Arg-Gly-Asp-(Phe)-Phe (IQCA-TAFF) as a model compound, the molecular modeling, synthesis, and an evaluation system for a novel anti-thrombotic agent were investigated. The synthesis of IQCA-TAFF was achieved by coupling 3S-tetrahydro-isoquinoline-3-carboxylic acid (IQCA) and Thr-Ala-Arg-Gly-Asp(Phe)-Phe (TAFF). The molecular modeling indicated that IQCA-TAFF was able to occupy the active site pocket of P-selectin with its IQCA moiety and to block GPIIb/IIIa fibrinogen-binding sites with its TAFF moiety, respectively. These are consistent with the dual inhibition of the expressions of P-selectin and GPIIb/IIIa, and with the in vitro anti-platelet aggregation activity of IQCA-TAFF. Besides, the dual suppression of P-selectin and GPIIb/IIIa leads to significant in vivo efficacy of IQCA-TAFF, 500-fold higher than those of IQCA and TAFF, respectively. Transmission electron microscopy (TEM) images indicated that in water, IQCA-TAFF concentration-dependently formed nano-globes. The molecular modeling, in vitro bioassay, in vivo bioassay, action mechanism investigation, and nano-image visualization together constitute a model system to characterize the anti-thrombotic agent capable of simultaneously inhibiting P-selectin and GPIIb/IIIa mediated thrombosis.

Synthesis and in vivo lead detoxification evaluation of Poly-α,ß-dl-aspartyl-l-methionine.

To increase the metal selectivity of polyaspartic acid, a so-called green chelant, poly-α,ß-dl-aspartyl-l-methionine (PDM) was synthesized as a novel lead chelating agent. The phosphoric acid (80%) catalyzed thermal poly condensation of dl-aspartic acid provided poly succinimide, which was amidated with l-methionine to form PDM (MW: 29161). At the doses of 0.1, 1.0, and 10.0 nmol/kg, either by intraperitoneal injection (i.p.) or oral administration, PDM removed Pb from the spleens, hearts, and kidneys of mice, especially dose-dependently decreasing the accumulation of Pb in the brains, livers, and femurs of the mice, and did not interfere with the essential metals, including Cu, Fe, Mn, and Ca. Even at the dose of 0.1 nmol/kg, the i.p. injection of PDM removed Pb from the spleens, hearts, and kidneys of mice and increased the amount of urinary volume and urinary Pb, and the amount of fecal matter and the amount of fecal Pb, resulting in effective removal of Pb from the body of mice given Pb by i.p. injection. Our findings revealed that in aqueous solution PDM formed diverse nanospecies.

A class of novel N-(1-methyl-ß-carboline-3-carbonyl)-N'-(aminoacid-acyl)-hydrazines: aromatization leaded design, synthesis, in vitro anti-platelet aggregation/in vivo anti-thrombotic evaluation and 3D QSAR analysis.

High anti-thrombotic activity of aminoacid modified tetrahydro-ß-carbolines was generally correlated with a small proximity of the side chain of the aminoacid residue to the carboline-cycle. This paper explored that the aromatization of the tetrahydro-ß-carboline-cycle of N-(1-methyl-ß-tetrahydrocarboline-3-carbonyl)-N'-(aminoacid-acyl)-hydrazines leaded to N-(1-methyl-ß-carboline-3-carbonyl)-N'-(aminoacid-acyl)-hydrazines and decreased the proximity of the side chain of the aminoacid residue to the carboline-cycle. The in vitro activities of inhibiting pig platelet aggregation induced by PAF, ADP, and AA, as well as the in vivo anti-thrombotic activities of inhibiting rat thrombosis of these aromatized derivatives were generally higher than that of N-(1-methyl-ß-tetrahydrocarboline-3-carbonyl)-N'-(aminoacid-acyl)-hydrazines. The understanding was also obtained from the 3D QSAR analysis.

Pyrolo[1,2:4,5]-1,4-dioxopyrazino[1,2:1,6]pyrido[3,4-b]indoles: a group of urokinase inhibitors, their synthesis, and stereochemistry-dependent activity.

Antifibrinolytic agents are required during complex surgeries to decrease bleeding; their pro-thrombotic potency and efficacy in causing hemostasis has attracted much attention. To discover new inhibitors of urokinase with high selectivity for antifibrinolytic effects over pro-thrombotic effects, the 12-position of (5aS,12S,14aS)- and (5aS,12R,14aS)-5,14-dioxo-1,2,3,5,5a,6,11, 12,14,14a-decahydro-5H,14H-pyrolo[1,2:4,5]pyrazino[1,2:1,6]pyrido[3,4-b]indoles were modified with L-Ala, L-Asp, L-Phe, L-Trp, L-Lys, L-Ser, Gly, and L-Leu to provide 16 (5aS,12S,14aS) and (5aS,12R,14aS) derivatives. In a murine bleeding model, the (5aS,12S,14aS) derivatives containing L-Ala, L-Asp, L-Phe, and L-Trp induced blood coagulation for the treated mice; they also stimulated thrombus formation in a rat thrombosis model, but the other derivatives inhibited thrombosis. The most potent compound, the L-Asp derivative, showed a good therapeutic window: the minimum effective dose for coagulation was <1 nmol kg(-1), whereas at 10 nmol kg(-1), no pro-thrombotic effect was observed. This type of coagulation action was correlated with a mechanism of urokinase inhibition, and these results could lead to the discovery of novel urokinase inhibitors.

One single HPLC-PDA/(-)ESI-MS/MS analysis to simultaneously determine 30 components of the aqueous extract of Rabdosia rubescens.

In China the leaves of Rabdosia rubescens have been cooked in water and widely drank to treat inflammatory and pain related diseases. To explore the components that were possibly absorbed by people the aqueous extract of the leaves was prepared, and one single HPLC-PDA/(-)ESI-MS/MS analysis was developed to simultaneously determine the components. Using the HPLC-PDA analysis 39 peaks were found in the aqueous extract, while using the (-)ESI-MS/MS analysis we were able to identify 30 peaks represented components, including 5 nucleic acids, 21 phenolic acids and 4 diterpenoids. On mouse models the in vivo anti-inflammation and analgesic actions demonstrate that 0.32 g/kg of the aqueous extract of the leaves of Rabdosia rubescens can effectively inhibit the inflammation-induced chronic pain.

From Cerius² based stereoview to mouse and enzyme: the model systems for discovery of novel urokinase inhibitors.

Antifibrinolytic therapy during major complex surgery could reduce blood loss and allogeneic transfusion. Novel antagonists of the plasminogen activator and the corresponding model system are of clinical importance. In this paper (1S,2'S,3S)-1-[2-(S)-carboxylindolemethylenemethineaminoeth-1-yl]-2,3,4,5-tetrahydropyrolo[1,2:1,6]pyrazino[3,4:2,3]-1,2,3,4-tetrahydrocarboline-2,5-dione (CIPPC) was presented as a novel antagonist of plasminogen activator, and its blood coagulation and action mechanism were investigated by using a model system which consisted of a mouse-tail bleeding assay, in vitro and in vivo fibrinolysis inhibition assays, a thrombus formation assay and a plasminogen (PLG) electrophoresis assay.

A class of Trp-Trp-AA-OBzl: Synthesis, in vitro anti-proliferation/in vivo anti-tumor evaluation, intercalation-mechanism investigation and 3D QSAR analysis.

From the anti-tumor active N-tryptophanyl-ß-carboline-3-carboxylic acid benzyl ester and ß-carboline-3-carbonyltryptophan benzyl ester, a pharmacophore, Trp-Trp-OBzl, was drawn. Based on the DOCK scores amino acid residue was inserted into the C-terminus of Trp-Trp-OBzl and twenty Trp-Trp-AA-OBzls (AA = amino acid residues) were provided as DNA intercalators. On the in vitro and in vivo models seventeen Trp-Trp-AA-OBzls were anti-tumor active, and twelve Trp-Trp-AA-OBzls were more active than cytarabine. In acute toxicity assay Trp-Trp-AA-OBzls did not damage the immunologic function and had an LD(50) of more than 500 mg/kg. The relationships of structure and activity were analyzed with 3D QSAR. The action mechanism studies revealed that the in vivo anti-tumor action of Trp-Trp-AA-OBzls was the result of DNA intercalation.

Lead detoxification activities of a class of novel DMSA--amino acid conjugates.

The coupling of the 1-carboxyl of DMSA with l-amino acids led to a class of novel 1-(carbonyl-l-amino-acid)-2,3-dimercaptosuccinic acids (DMSA--amino acid conjugates, DMSA-Gly, -Ser, -Val, -Leu, -Ile, -Asn, -Asp, -Gln, -Glu, -Met, -Phe, and -Trp). In the in vivo evaluation of Pb-loaded mice, 0.4 mmol/kg of the conjugates effectively decreased the Pb levels of the femur, brain, kidney, liver, and blood, greatly enhanced urination, and increased the Pb levels of both urine and feces, while causing no redistributions of Pb to the other organs, especially to the brain. With respect to lowering the bone and brain Pb, DMSA-Ile, -Asn, -Gln, and -Met were more effective than DMSA. This benefit was attributed to their high transmembrane ability. In contrast to Pb, the essential metals such as Fe, Cu, Zn, and Ca of the treated mice were not affected by the administration of the conjugates. Silico molecular modeling predicted that the conjugates had little hepatotoxicity, except possibly for DMSA-Phe.

A class of oral N-[(1S,3S)-1-methyl-1,2,3,4-tetrahydro-ß-carboline-3-carbonyl]- N'-(amino-acid-acyl)hydrazine: discovery, synthesis, in vitro anti-platelet aggregation/in vivo anti-thrombotic evaluation and 3D QSAR analysis.

The in vivo anti-thrombotic activities of amino acid modified tetrahydro-ß-carbolines depended upon the proximity of the side chain of the amino acid residue to the carboline-cycle. Based on this proximity the computerized screening of various tetrahydro-ß-carboline derivatives was performed and N-[(1S,3S)-1-methyl-1,2,3,4-tetrahydro-ß-carboline-3-carbonyl]-N'-(amino-acid-acyl)hydrazines were explored having large proximity. The in vivo anti-thrombotic assays explored that at a dose of 10 nmol/kg eighteen novel N-[(1S,3S)-1-methyl-1,2,3,4-tetrahydro-ß-carboline-3-carbonyl]-N'-(amino-acid-acyl)hydrazines were orally efficacious.

Development of highly effective three-component cytoprotective adjuncts for cisplatin cancer treatment: synthesis and in vivo evaluation in S180-bearing mice.

A series of chelants (3a-s) composed of a glucosyl tail, an amino acid side chain and a dithiocarbamate group were designed, synthesized, and evaluated. By co-administering with cisplatin, 3a-s were able to decrease the accumulation of platinum in the organs, maintain the accumulation of platinum in the tumor tissues, and increase the urinary and fecal platinum, as well as increasing the voided volume of the treated S180-bearing mice. Compared to S180-bearing mice treated with cisplatin alone, the co-administered mice lost no spleen, kidney, liver, brain and heart weights, lost less body weight, and showed no increase in tumor weight.