Ferrocene-Conjugated Oxidovanadium(IV) Complexes as Potent Near-IR Light Photocytotoxic Agents

Ferrocene-conjugated oxidovanadium(IV) complexes [VO(Fc-tpy)(B)](ClO4)(2) (1-4) and [VO(Ph-tpy)(dppz)](ClO4)(2) (5) as a control [Fc = (eta(5)-C5H4)Fe-II(eta(5)-C5H5), Fc-tpy = 4'-ferrocenyl-2,2':6',2 `'-terpyridine, Ph-tpy = 4'-phenyl-2,2':6',2 `'-terpyridine, B = heterocyclic base: 2,2'-bipyridine (bpy in 1), 1,10-phenanthroline (phen in 2), dipyridoquinoxaline (dpq in 3), dipyridophenazine (dppz in 4)] were prepared and their DNA binding, DNA photocleavage activity and photocytotoxicity studied. The crystal structure of [VO(Fc-tpy)(bpy)](PF6)(2)center dot 3Me(2)CO shows a vanadyl group in six-coordinate (VON5)-O-IV coordination geometry, in which Fc-tpy and bpy display tridentate meridional and bidentate N-donor axial-equatorial binding modes, respectively. The one-electron paramagnetic complexes exhibit a charge-transfer band near 590 nm in DMF. The V-IV/V-III redox couple in 1-4 appears near -0.7 V, whereas the Fc moiety shows a response near 0.6 V vs. SCE in DMF/0.1 M TBAP. The complexes are good binders to calf thymus DNA with K-b values of 10(4)-10(6) M-1. DNA melting and viscometric data suggest groove and/or partial intercalative DNA binding of the complexes. Complexes 3-5 display DNA photocleavage activity in nearIR light of 785 nm. Complex 4 shows significant photocytotoxicity in visible light (400-700 nm) in HeLa cells with low dark toxicity.

Design, synthesis of some new (2-aminothiazol-4-yl)methylester derivatives as possible antimicrobial and antitubercular agents

A series of (2-aminothiazol-4-yl)methylester (5a-t) derivatives were synthesized in good yields and characterized by H-1 NMR, C-13 NMR, mass spectral and elemental analyses. The crystal structure of 5a was evidenced by X-ray diffraction study. The compounds were evaluated for their preliminary in vitro antibacterial, antifungal activity and were screened for antitubercular activity against Mycobacterium tuberculosis H37Rv strain. The synthesized compounds displayed interesting antimicrobial activity. (C) 2012 Elsevier Masson SAS. All rights reserved.

Evaluation of DNA binding, antioxidant and cytotoxic activity of mononuclear Co(III) complexes of 2-oxo-1,2-dihydrobenzoh]quinoline-3-carbaldehyde thiosemicarbazones

Four new 2-oxo-1,2-dihydrobenzoh]quinoline-3-carbaldehyde N-substituted thiosemicarbazone ligands (H-2-LR, where R = H, Me, Et or Ph) and their corresponding new cobalt(III) complexes have been synthesized and characterized. The structures of the complexes 2 and 3 were determined by single crystal X-ray diffraction analysis. The interactions of the new complexes with DNA were investigated by absorption, emission and viscosity studies which indicated that the complexes bind to DNA via intercalation. Antioxidant studies of the new complexes showed that the significant antioxidant activity against DPPH radical. In addition, the in vitro cytotoxicity of complexes 1-4 against A549 cell line was assayed which showed higher cytotoxic activity with lower IC50 values indicating their efficiency in killing the cancer cells even at very low concentrations. (C) 2012 Elsevier Masson SAS. All rights reserved.

Spirodiazaselenuranes: synthesis, structure and antioxidant activity

In this paper, the synthesis, characterization and glutathione peroxidase and peroxynitrite scavenging activities of a series of stable spirodiazaselenuranes are described. The spiro compounds were synthesized in good yields by oxidative cyclization of diaryl selenides bearing amide moieties. All the selenides and spiro derivatives were characterized by H-1, C-13 and Se-77 NMR spectroscopy, mass spectral techniques and the structures of some of the spirodiazaselenuranes were confirmed by single crystal X-ray crystallography. The structures reveal that the selenium atom occupies the center of a distorted trigonal bipyramid core with two nitrogen atoms occupying the apical positions and two carbon atoms and the selenium lone pair occupying the equatorial positions. Mechanistic investigations indicate that the spirocyclization occurs via the formation of selenoxide intermediates. The new compounds were evaluated for their glutathione peroxidase (GPx) mimetic activity by using H2O2 as a substrate and glutathione (GSH) as a co-substrate. It was found that the substituents attached to the nitrogen atom of the selenazole ring have a significant effect on the GPx activity. While the introduction of electron withdrawing groups such as -Cl, -Br etc. to the phenyl ring decreases the activity, the introduction of electron donating groups such as -OH, -OMe significantly enhances the GPx activity of both diaryl selenides and spirodiazaselenuranes. In addition to GPx activity, the selenides and spiro derivatives were studied for their ability to inhibit peroxynitrite (PN)-mediated nitration of bovine serum albumin (BSA) and oxidation of dihydrorhodamine 123. These studies indicate that the diarylselenides effectively inhibit the PN-mediated nitration and oxidation reactions by reacting with PN to produce the corresponding spirodiazaselenuranes.

Tertiary amine-based glutathione peroxidase mimics: some insights into the role of steric and electronic effects on antioxidant activity

In this work, several tertiary amine-based diaryl diselenides were synthesized and evaluated for their glutathione peroxidase (GPx)-like antioxidant activities using hydrogen peroxide, tert-butyl hydroperoxide and cumene hydroperoxide as substrates and thiophenol (PhSH) and glutathione (GSH) as co-substrates. A comparison of the GPx-like activity of 4-methoxy-substituted N,N-dialkylbenzylamine-based diselenides with that of the corresponding 6-methoxy-substituted compounds indicates that the activity highly depends on the position of the methoxy substituent. Although the methoxy group at 4- and 6-position alters the electronic properties of selenium, the substitution at the 6-position provides the required steric protection for some of the key intermediates in the catalytic cycle. A detailed experimental and theoretical investigation reveals that the 6-methoxy substituent prevents the undesired thiol exchange reactions at the selenium centers in the selenenyl sulfide intermediates. The 6-methoxy substituent also prevents the formation of seleninic and selenonic acids. When PhSH is used as the thiol co-substrate, the 4-methoxy-substituted diselenides exhibit GPx-like activity similar to that of the parent compounds as the 4-methoxy substituent does not block the selenium center in the selenenyl sulfide intermediates from thiol exchange reactions. In contrast, the 4-methoxy substituent significantly enhances the GPx-like activity of the diselenides when glutathione (GSH) is used as the co-substrate. (C) 2012 Elsevier Ltd. All rights reserved.

Studies on the Aging Characteristics of Base Oil with Amine Based Antioxidant in Steel-on-Steel Lubricated Sliding

An industrial base oil, a blend of different paraffin fractions, is heated to 130 degrees C (1) in the ambient and (2) for use as a lubricant in a steel pin on a steel disk sliding experiment. The base oil was tested with and without test antioxidants: dimethyl disulfide (DMDS) and alkylated diphenylamine (ADPA). Primary and secondary oxidation products were monitored continuously by FTIR over a 100 h period. In addition, friction and wear of the steel pin were monitored over the same period and the chemical transformation of the pin surface was monitored by XPS. The objective of this work is to observe the catalytic action of the steel components on the oil aging process and the efficacy of the antioxidant to reduce oxidation of oil used in tribology as a lubricant. Possible mechanistic explanations of the aging process as well as its impact on friction and wear are discussed.

A trust model for routing in MANETs: a cognitive agents based approach

Mobile ad hoc networks (MANETs) is one of the successful wireless network paradigms which offers unrestricted mobility without depending on any underlying infrastructure. MANETs have become an exciting and im- portant technology in recent years because of the rapid proliferation of variety of wireless devices, and increased use of ad hoc networks in various applications. Like any other networks, MANETs are also prone to variety of attacks majorly in routing side, most of the proposed secured routing solutions based on cryptography and authentication methods have greater overhead, which results in latency problems and resource crunch problems, especially in energy side. The successful working of these mechanisms also depends on secured key management involving a trusted third authority, which is generally difficult to implement in MANET environ-ment due to volatile topology. Designing a secured routing algorithm for MANETs which incorporates the notion of trust without maintaining any trusted third entity is an interesting research problem in recent years. This paper propose a new trust model based on cognitive reasoning,which associates the notion of trust with all the member nodes of MANETs using a novel Behaviors-Observations- Beliefs(BOB) model. These trust values are used for detec- tion and prevention of malicious and dishonest nodes while routing the data. The proposed trust model works with the DTM-DSR protocol, which involves computation of direct trust between any two nodes using cognitive knowledge. We have taken care of trust fading over time, rewards, and penalties while computing the trustworthiness of a node and also route. A simulator is developed for testing the proposed algorithm, the results of experiments shows incorporation of cognitive reasoning for computation of trust in routing effectively detects intrusions in MANET environment, and generates more reliable routes for secured routing of data.

Antioxidant and oxidative stress parameters in brain of Heteropneustes fossilis under air exposure condition; role of mitochondrial electron transport chain

Many fishes are exposed to air in their natural habitat or during their commercial handling. In natural habitat or during commercial handling, the cat fish Heteropneustes fossilis is exposed to air for > 24 h. Data on its oxidative metabolism in the above condition are not available. Oxidative stress (OS) indices (lipid and protein oxidation), toxic reactive oxygen species (ROS: H2O2) generation, antioxidative status (levels of superoxide dismutase, catalase, glutathione peroxidase and reductase, ascorbic acid and nonprotein sulfhydryl) and activities of electron transport chain (ETC) enzymes (complex I-IV) were investigated in brain tissue of H. fossilis under air exposure condition (0, 3, 6, 12 and 18 h at 25 degrees C). Decreased activities of antioxidant (except catalase) and ETC enzymes (except complex II) with increased H2O2 and OS levels were observed in the tissue under water deprivation condition. Positive correlation was observed for complex II activity and non-protein thiol groups with time period of air exposure. The critical time period to induce OS and to reduce most of the studied antioxidant level in brain was found to be 3-6 h air exposure. The data can be useful to minimize the stress generated during commercial handling of the live fishes those exposed to air in general and H. fossilis in particular. (C) 2013 Elsevier Inc. All rights reserved.

Forming Networks of Strategic Agents with Desired Topologies

Many networks such as social networks and organizational networks in global companies consist of self-interested agents. The topology of these networks often plays a crucial role in important tasks such as information diffusion and information extraction. Consequently, growing a stable network having a certain topology is of interest. Motivated by this, we study the following important problem: given a certain desired network topology, under what conditions would best response (link addition/deletion) strategies played by self-interested agents lead to formation of a stable network having that topology. We study this interesting reverse engineering problem by proposing a natural model of recursive network formation and a utility model that captures many key features. Based on this model, we analyze relevant network topologies and derive a set of sufficient conditions under which these topologies emerge as pairwise stable networks, wherein no node wants to delete any of its links and no two nodes would want to create a link between them.

Synthetic glutathione peroxidase mimics: effect of nucleophilicity of the aryl thiol cofactor on the antioxidant activity

Catalytic activity of a series of potent amide- and amine-based organoselenium compounds are studied in the presence of various aromatic thiols having electron donating and electron withdrawing substituents on the phenyl ring. This study suggests that the antioxidant activities of the synthetic GPx mimics can be significantly increased by the incorporation of a suitable electron donating group on the phenyl ring of an aromatic thiol.

Design and synthesis of positional isomers of 5 and 6-bromo-1-(phenyl)sulfonyl]-2-(4-nitrophenoxy)methyl]-1H-benzimida zoles as possible antimicrobial and antitubercular agents

In this Letter, we report the structure activity relationship (SAR) studies on series of positional isomers of 5(6)-bromo-1-(phenyl)sulfonyl]-2-(4-nitrophenoxy)methyl]-1H-benzim idazoles derivatives 7(a-j) and 8(a j) synthesized in good yields and characterized by H-1 NMR, C-13 NMR and mass spectral analyses. The crystal structure of 7a was evidenced by X-ray diffraction study. The newly synthesized compounds were evaluated for their in vitro antibacterial activity against Staphylococcus aureus, (Gram-positive), Escherichia coil and Klebsiella pneumoniae (Gram-negative), antifungal activity against Candida albicans, Aspergillus flavus and Rhizopus sp. and antitubercular activity against Mycobacterium tuberculosis H37Rv, Mycobacterium smegmatis, Mycobacterium fortuitum and MDR-TB strains. The synthesized compounds displayed interesting antimicrobial activity. The compounds 7b, 7e and 7h displayed significant activity against Mycobacterium tuberculosis H37Rv strain.

Synthesis and evaluation of 2,5-di(4-aryloylaryloxymethyl)-1,3,4-oxadiazoles as anti-cancer agents

A series of 2,5-di(4-aryloylaryloxymethyl)-1,3,4-oxadiazoles 9a-j were obtained via multistep synthesis from hydroxybenzophenones 4a-e. The cytotoxicity of compounds 9a-j was evaluated against human leukemia cell lilies (K562 and CEM). The compounds exhibited moderate to good anti-cancer activity with compounds 9b and 9i having a chloro group exhibiting the best activity (IC50 = 10 mu M). Compound 9i exhibited activity against both the cell lines and 9b only exhibited activity against CEM. Further, a lactate dehydrogenase (LDH) assay and DNA fragmentation studies of the compounds 9a-j were also performed. (C) 2013 Elsevier Masson SAS. All rights reserved.

Antitumor and antioxidant status of Terminalia catappa against Ehrlich ascites carcinoma in Swiss albino mice

Objective: The present study was undertaken to evaluate the antitumor and antioxidant status of ethanol extract of Terminalia catappa leaves against Ehrlich ascites carcinoma (EAC) in Swiss albino mice. Materials and Methods: The leaves powder was extracted with Soxhlet apparatus and subjected to hot continuous percolation using ethanol (95% v/v). Tumor bearing animals was treated with 50 and 200 mg/kg of ethanol extract. EAC induced in mice by intraperitoneal injection of EAC cells 1 x 10(6) cells/mice. The study was assed using life span of EAC-bearing hosts, hematological parameters, volume of solid tumor mass and status of antioxidant enzymes such as lipid peroxidation (LPO), reduced glutathione (GSH), superoxide dismutase (SOD) and catalase (CAT) activities. Total phenolics and flavonoids contents from the leaves extract were also determined. Results: Total phenolics and flavonoids contents from the leaves extract were found 354.02 and 51.67 mg/g extract. Oral administration of ethanol extract of T. catappa (50 and 200 mg/kg) increased the life span (27.82% and 60.59%), increased peritoneal cell count (8.85 +/- 0.20 and 10.37 +/- 0.26) and significantly decreased solid tumor mass (1.16 +/- 0.14 cm(2)) at 200 mg/kg as compared with EAC-tumor bearing mice (P < 0.01). Hematological profile including red blood cell count, white blood cell count, hemoglobin (11.91 +/- 0.47 % g) and protein estimation were found to be nearly normal levels in extract-treated mice compared with tumor bearing control mice. Treatment with T. catappa significantly decreased levels of LPO and GSH, and increased levels of SOD and CAT activity (P < 0.01). Conclusion: T. catappa exhibited antitumor effect by modulating LPO and augmenting antioxidant defense systems in EAC bearing mice. The phenolic and flavonoid components in this extract may be responsible for antitumor activity.

Sufficient conditions for formation of a network topology by self-interested agents

Networks such as organizational network of a global company play an important role in a variety of knowledge management and information diffusion tasks. The nodes in these networks correspond to individuals who are self-interested. The topology of these networks often plays a crucial role in deciding the ease and speed with which certain tasks can be accomplished using these networks. Consequently, growing a stable network having a certain topology is of interest. Motivated by this, we study the following important problem: given a certain desired network topology, under what conditions would best response (link addition/deletion) strategies played by self-interested agents lead to formation of a pairwise stable network with only that topology. We study this interesting reverse engineering problem by proposing a natural model of recursive network formation. In this model, nodes enter the network sequentially and the utility of a node captures principal determinants of network formation, namely (1) benefits from immediate neighbors, (2) costs of maintaining links with immediate neighbors, (3) benefits from indirect neighbors, (4) bridging benefits, and (5) network entry fee. Based on this model, we analyze relevant network topologies such as star graph, complete graph, bipartite Turan graph, and multiple stars with interconnected centers, and derive a set of sufficient conditions under which these topologies emerge as pairwise stable networks. We also study the social welfare properties of the above topologies.

Aptamers as Theranostic Agents: Modifications, Serum Stability and Functionalisation

Aptamers, and the selection process known as Systematic Evolution of Ligands by Exponential Enrichment (SELEX) used to generate them, were first described more than twenty years ago. Since then, there have been numerous modifications to the selection procedures. This review discusses the use of modified bases as a means of enhancing serum stability and producing effective therapeutic tools, as well as functionalising these nucleic acids to be used as potential diagnostic agents.