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Integrins α4β1/ α9β1 are important in the pathogenesis and progression of inflammatory and autoimmune diseases by their roles in leukocyte activation and trafficking. Natalizumab, a monoclonal antibody selectively targeting α4β1 integrin and blocking leukocyte trafficking to the central nervous system, is an immunotherapy for multiple sclerosis (MS). However, due to its adverse effects associated with chronic treatment, alternative strategies using small peptide mimetic inhibitors are being sought. In the present study, we synthesized and characterized visabron c (4–4), a backbone cyclic octapeptide based on the sequence TMLD, a non-RGD unique α4β1 integrin recognition sequence motif derived from visabres, a proteinous disintegrin from the viper venom. Visabron c (4–4) was selected from a minilibrary with conformational diversity based on its potency and selectivity in functional adhesion cellular assays. Visabron c (4–4)’s serum stability, pharmacokinetics, and therapeutic effects following ip injection were assessed in an experimental autoimmune encephalomyelitis (EAE) animal model. Furthermore, visabron c (4–4)’s lack of toxic effects in mice was verified by blood analysis, tissue pathology, immunogenicity, and “off-target” effects, indicating its significant tolerability and lack of immunogenicity. Visabron c (4–4) can be delivered systemically. The in vitro and in vivo data justify visabron c (4–4) as a safe alternative peptidomimetic lead compound/drug to monoclonal anti-α4 integrin antibodies, steroids, and other immunosuppressant drugs. Moreover, visabron c (4–4) design may pave the way for developing new therapies for a variety of other inflammatory and/or autoimmune diseases.

Recent developments in near-infrared (NIR) dyes and imaging modalities enable tumor fluorescent images in preclinical and clinical settings. However, NIR dyes have several drawbacks, and therefore,...

Recent developments in near-infrared (NIR) dyes and imaging modalities enable tumor fluorescent images in preclinical and clinical settings. However, NIR dyes have several drawbacks, and therefore, there is an unmet diagnostic need for NIR dye encapsulation in appropriate pharmaceutical nanocarriers with targeting abilities for the purpose of achieving effective diagnosis and image-guided surgeries. Because integrin receptors are established diagnostic targets, the cyclic Arg-Gly-Asp (RGD) peptides, recognizing the α

Newly synthesized acylethanolamide derivatives oleoyl-L-valinolamide (1), oleoyl-D-valinolamide (2), elaidoyl-L-valinolamide (3), elaidoyl-D-valinolamide (4) stearoyl-L-valinolamide (5), and palmitoyl-L-valinolamide (6) were investigated in mice as antiobesity compounds. Compounds 1, 2, 5, 6 significantly decreased body weight by 6.57% following eight injections of 1 mg/kg i.p. during 39 days, while 3 and 4 showed no such activity. Receptor binding indicated that no compound activated CB1, CB2, PPARα, or TRPV1 receptors. Hypothalamic RT-PCR showed that mRNA expression of the anorexigenic genes POMC and CART was up-regulated by 1, 2, 5 and 1, 2, respectively, while that of the orexigenic genes NPY and CaMKK2 was down-regulated by the respective compounds 1, 5, 6 and 1, 2, 5. Oleoyl-L-valinolamide enhances anorectic pathways and lead to decreased glucose levels, enhanced locomotor activity, and improved cognition. Effects of oleoyl-L-valinolamide on weight were dose-dependent, and it could be given orally. 1, 2, 4, 5 down-regulated FAAH mRNA expression.

α-Lipoic acid (α-LA), a natural thiol antioxidant, and Tempol, a synthetic free radical scavenger, are known to confer neuroprotection following ischemic insults in both in vivo and in vitro models. The aim of this study was to synthesize and characterize a conjugate of α-LA and Tempol linked by polyethylene glycol (PEG) in order to generate a more efficacious neuroprotectant molecule. AD3 (α-Tempol ester-ω-lipo ester PEG) was synthesized, purified, and characterized by flash chromatography and reverse phase high pressure liquid chromatography and by 1H nuclear magnetic resonance, infrared spectroscopy, and mass spectrometry. AD3 conferred neuroprotection in a PC12 pheochromocytoma cell line of dopaminergic origin, exposed to oxygen and glucose deprivation (OGD) insult measured by LDH release. AD3 exhibited EC50 at 10 μM and showed a 2–3-fold higher efficacy compared to the precursor moieties, indicating an intrinsic potent neuroprotective activity. AD3 attenuated by 25% the intracellular redox potential,...

A prominent feature of the stringent response is the accumulation of two unusual phosphorylated derivatives of GTP and GDP (pppGpp: 5'-triphosphate-3'-diphosphate, and ppGpp: 5'-3'-bis-diphosphate), collectively called (p)ppGpp, within a few seconds after the onset of amino-acid starvation. The synthesis of these 'alarmone' compounds is catalyzed by RelA homologues. Other features of the stringent response include inhibition of stable RNA synthesis and modulation of transcription, replication, and translation. (p)ppGpp accumulation is important for virulence induction, differentiation and antibiotic resistance. We have synthesized a group of (p)ppGpp analogues and tested them as competitive inhibitors of Rel proteins in vitro. 2'-Deoxyguanosine-3'-5'-di(methylene bisphosphonate) [compound (10)] was found as an inhibitor that reduces ppGpp formation in both Gram-negative and Gram-positive bacteria. In silico docking together with competitive inhibition analysis suggests that compound (10) inhibits activity of Rel proteins by competing with GTP/GDP for its binding site. As Rel proteins are completely absent in mammalians, this appears to be a very attractive approach for the development of novel antibacterial agents.

The first examples of diborane (4) compounds derived from amine cyanoboranes are described. A series of monobromo derivatives of amine cyanoboranes (A:BHBrCN), and dibromo derivatives (A:BBr 2 CN), 1 – 7 , were prepared. Lithiation of the monobromo derivative of trimethylamine cyanoborane, using n -BuLi, did not produce the C-lithiated intermediate Li + [CH 2 NMe 2 BHBrCN] − , but instead the B-lithiated intermediate Li + [Me 3 NBHCN] − , was obtained. This intermediate, when allowed to react for 16 h, coupled with the un-lithiated trimethylamine monobromocyanoborane (Me 3 NBHBrCN) and resulted in diborane (4) derivative formation as the 2LiBr complex. The same result was obtained when one equiv of the trimethylamine monobromocyanoborane was added to the reaction mixture 1 h after lithiation. Following the same procedure, novel diborane (4) derivatives of amine cyanoboranes were successfully obtained, 8 – 11 , as their 2LiBr complexes from the monobromo derivatives of the corresponding amine cyanoboranes. Molecular structures of the trimethylamine dibromocyanoborane, 6 , and the triethylamine dibromocyanoborane, 7 , were determined using X-ray crystallography.

KTS-disintegrins are a subfamily of short monomeric disintegrins that are potent and selective inhibitors of α1β1 integrin. The amino acid sequence of the new KTS-disintegrin, viperistatin, differs from previously characterized obtustatin in three residues at position 24 (within the integrin binding loop), 38 (hydrophobic core) and 40 (C-terminal region). Noteworthy, viperistatin is about 25-fold more potent than obtustatin inhibiting the binding of this integrin to collagen IV. Synthetic peptides representing the full-length of integrin-binding loops of these disintegrins showed that the Leu24/Arg substitution appears to be partly responsible for the increased inhibitory activity of viperistatin over obtustatin.

We have developed a new method for the preparation of esters of trimethylamine−dibromocarboxyborane (Me3N·BBr2COOR), from trimethylamine−carboxyborane, in a one-pot reaction. The reaction involves the treatment of trimethylamine−carboxyborane with 2.5 equiv of Br2 in the appropriate alcohol for 4 h at 0 °C, for compounds 1−5 (R = Me, Et, n-Pr, CH2CH2Cl, CH2CF3), and 5 equiv of Br2 for 8 h under the same conditions, for compounds 6−8 (R = n-Bu, i-Bu, i-Pe). Compounds 1−5 were obtained in high purity and in essentially quantitative yields (∼99%). Compounds 6−8 were purified from traces of monobromo product and the alcohol by column chromatography. Molecular structures for the compounds 2, 6, and 7 were determined by X-ray crystallography.

alpha-Lipoic acid [5-[1,2]-dithiolan-3-yl-pentanoic acid (LA)] is a natural antioxidant and cofactor of several enzymes. It increases the glucose transport activity in skeletal muscles and adipocytes in a non-insulin dependent manner. Therefore, LA is widely used in Type 2 diabetic patients as an oral auxiliary drug. However, large doses of LA (0.8-1.8 gr/day p.o.) are required due to its unfavorable pharmacokinetic parameters. In order to improve these parameters, we synthesized ester and amide LA derivates. Two of these newly synthesized compounds, 5-[1,2]-dithiolan-3-yl-pentanoic acid 3-(5-[1,2]dithiolan-3yl-pentanoylamino)-propyl]-amide (AN-7) and 5-[1,2]-dithiolan-3-yl-pentanoic acid 3-(5-[1,2]-dithiolan-3yl-pentanoyloxy)-propyl ester (AN-8) augmented the rate glucose transport in myotubes in culture in the absence or presence of insulin. Their potency was 12-fold higher than that of the parent compound; their maximal stimulatory effect was 1.5-fold higher than that of LA. When tested in vivo in streptozotocin-diabetic C57/Black mice, AN-7 (10 mg/kg/day for 2 weeks, s.c.) reduced blood glucose level by 39% while a higher dose of LA (50 mg/kg/day for 2 weeks, s.c.) lowered it by 30%. These results indicate that AN-7 is more potent than LA in augmenting glucose transport in skeletal muscles and reducing blood glucose in diabetic animals.

Tatjana Momic,1 Jehoshua Katzhendler,1 Ela Shai,2 Efrat Noy,3 Hanoch Senderowitz,3 Johannes A Eble,4 Cezary Marcinkiewicz,5 David Varon,2 Philip Lazarovici11School of Pharmacy Institute for Drug Research, Faculty of Medicine, The Hebrew University of Jerusalem, 2Department of Hematology, Coagulation Unit, Hadassah-Hebrew University Medical Center, Jerusalem, Israel; 3Department of Chemistry, Bar-Ilan University, Ramat-Gan, Israel; 4Institute for Physiological Chemistry and Pathobiochemistry, University of Münster, Münster, Germany; 5Department of Bioengineering, College of Engineering, Temple University, Philadelphia, PA, USAAbstract: Linear peptides containing the sequence WKTSRTSHY were used as lead compounds to synthesize a novel peptidomimetic antagonist of α2β1 integrin, with platelet aggregation-inhibiting activity, named Vipegitide. Vipegitide is a 13-amino acid, folded peptidomimetic molecule, containing two α-aminoisobutyric acid residues at positions 6 and 8 and not stable in human serum. Substitution of glycine and tryptophan residues at positions 1 and 2, respectively, with a unit of two polyethylene glycol (PEG) molecules yielded peptidomimetic Vipegitide-PEG2, stable in human serum for over 3 hours. Vipegitide and Vipegitide-PEG2 showed high potency (7×10-10 M and 1.5×10-10 M, respectively) and intermediate efficacy (40% and 35%, respectively) as well as selectivity toward α2 integrin in inhibition of adhesion of α1/α2 integrin overexpressing cells toward respective collagens. Interaction of both peptidomimetics with extracellular active domain of α2 integrin was confirmed in cell-free binding assay with recombinant α2 A-domain. Integrin α2β1 receptor is found on the platelet membrane and triggers collagen-induced platelet aggregation. Vipegitide and Vipegitide-PEG2 inhibited α2β1 integrin-mediated adhesion of human and murine platelets under the flow condition, by 50%. They efficiently blocked adenosine diphosphate- and collagen I-induced platelet aggregation in platelet rich plasma and whole human blood. Higher potency of Vipegitide than Vipegitide-PEG2 is consistent with results of computer modeling of the molecules in water. These peptidomimetic molecules were acutely tolerated in mice upon intravenous bolus injection of 50 mg/kg. These results underline the potency of Vipegitide and Vipegitide-PEG2 molecules as platelet aggregation-inhibiting drug lead compounds in antithrombotic therapy.Keywords: adhesion, collagen I, platelets, integrin antagonist, peptidomimetic

One of the challenges in regenerative medicine is the development of novel biodegradable materials to build scaffolds that will support multiple cell types for tissue engineering. Here we describe the preparation, characterization, and cytocompatibility of homo- and hetero-polyesters of α-hydroxy amino acid derivatives with or without lactic acid conjugation. The polymers were prepared by a direct condensation method and characterized using gel permeation chromatography, (1)H-nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, differential scanning calorimetry, optical activity, and solubility. The surface charge of the polymers was evaluated using zeta potential measurements. The polymers were coated onto glass cover slips followed by characterization using nano-surface profiler, thin film reflectometry, and atomic force microscopy (AFM). Their interaction with endothelial and neuronal cells was assessed using adhesion, proliferation, and differentiation assays. Of the characterized polymers, Poly-HOVal-LA, but not Poly-(D)HOPhe, significantly augmented nerve growth factor (NGF)-induced neuronal differentiation of the PC12 pheochromcytoma cells. In contrast, Poly-HOLeu increased by 20% the adhesion of endothelial cells, but did not affect PC12 cell differentiation. NGF-induced Erk1/2 phosphorylation in PC12 cells grown on the different polymers was similar to the effect observed for cells cultured on collagen type I. While no significant association could be established between charge and the differentiative/proliferative properties of the polymers, AFM analysis indicated augmentation of NGF-induced neuronal differentiation on smooth polymer surfaces. We conclude that overall selective cytocompatibility and bioactivity might render α-hydroxy amino acid polymers useful as extracellular matrix-mimicking materials for tissue engineering.

We investigated the effect of various monofunctional platinum complexes on the thermal stability and conformation of a self-complementary 22-mer duplex oligonucleotide by means of CD and UV melting profiles. We studied several families of triamine complexes of the general formula PtA 2 AmCl where A 2 =(NH 3 ) 2 and ethylenediamine and where Am= N1 -4-methyl-pyridine, N7 -guanosine, and 9-ethyl-guanine. Platination by the N1 -4-methyl-pyridine and 9-ethyl-guanine complexes led to a decrease in the T m of the oligonucleotide by 2–11.5°C while platination with the N7 -guanosine complexes led to a rise in the melting temperature of the oligonucleotides by 4.5°C. A similar inverse correlation between the two groups of platinum compounds was found in the CD spectra. In all cases, the cis isomer had a more pronounced effect on both the melting curve and the CD spectrum. The cis isomer was found to have a more destabilizing effect than its trans counterpart. This indicates that the cis geometry in fact forces a greater structural constraint on the backbone of the double helix. We have also found that the sugar of the guanosine has a significant influence on both the T m and CD spectra; the sugar moiety contributes to the stability of the double helix, probably through the formation of hydrogen bonds.

A simple and highly sensitive method for the determination of short, medium and long-chain alcohols using high-performance liquid chromatography with fluorimetric detection is described. The alcohols were derivatized to their corresponding esters with (4-carboxyphenyl)-6-N,N-diethylaminobenzofuran. The esterification reaction proceeded rapidly and smoothly in acetonitrile at 60°C with 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (a coupling agent) in the presence of 4-dimethylaminopyridine (a base catalyst). The resulting esters of alcohols from methanol to eicosanol (C 1 –C 20 -ol) were separated on a reversed-phase column (Ultrasphere C 8 ) with gradient elution (acetonitrile–water) and detected fluorometrically (excitation 387, emission 537 nm). The lower limits of detection (signal-to-noise ratio of 3) for the derivatized alcohols were in the range of 0.2–0.5 pg.

The thermodynamics, pH dependency and solvent effects of the fragmentation reaction of a series of α-oxyiminobenzylphosphonate monomethyl esters [(E)-1a–f] were examined in water and other hydroxylic solvents by UV and by 31P NMR spectroscopy at pH 0–3.1. The fragmentation of compounds (E)-1a–f was found to be a first-order reaction in substrate over the acidity range studied, while the dependence on the acidity is more complex, with rate constants k1 and k2. The ρ values corresponding to the first and second order rate constants were −1.12 and −0.835, respectively, indicating that the reaction is facilitated by electron-donating substituents, which probably enhance the protonation of the oxime OH group. Activation parameters for k1 and k2 reactions were also calculated. The near- zero values of the entropies of activation obtained are consistent with a dissociative transition state with almost no bonding to a nucleophilic solvent. Monitoring the fragmentation reaction of (E)-1a in several binary alcohol–water mixtures at different acidities showed that the reaction rate is enhanced by the alcohol’s acidity and not hampered by the steric requirements of the alcohol molecule. This rules out in our opinion, the likelihood for nucleophilic solvent assistance in the rate-determining step. On the other hand, product studies show that both the nucleophilicity and the steric requirements of the alcohol are of importance in determining the product formed in the fragmentation of (E)-1a. The highest selectivity (S) value was found for MeOH, while S values of

The mode of action of antitumour anthraquinone derivatives (i.e. mitoxantrone) is not clearly established yet. It includes, among others, intercalation and binding to DNA, bioreduction and aerobic redox cycling. A series of anthraquinone derivatives, with potentially bioreducible groups sited in the side chain, have been synthesized and biologically evaluated. Their redox and cytotoxic activities were screened. Derivatives which bear a 2-(dimethylamino)ethylamino substituent, known to confer high DNA affinity, demonstrated cytotoxicity but not redox activity (beside the anthraquinone reduction). Conversely, derivatives which showed redox activity were not cytotoxic toward the P388 cell line. The results suggest that bioreduction is not the main mode of action in the cytotoxicity of anthraquinones.

The role of the membrane hydration layer in preventing membrane oxidative damage has been evaluated by comparing bilayers with and without an extended hydration layer. The extended hydration layer was obtained through the use of a novel phospholipid in which polyethylene glycol of 2000 Da molecular mass (PEG2000) was covalently attached to the phosphate headgroup of a phospholipid backbone to form dihexadecylphosphatidyl PEG2000—α-{[2,3-bis(hexadecyloxy)propoxy](h ydroxyphosphinoyl}-ω-methoxypoly(oxyethane-1,2-diyl) monosodium salt. The amount of water bound to free PEG and to the DHP-PEG2000 was determined by differential scanning calorimetry. Small unilamellar liposomes composed of egg phosphatidylcholine and DHP-PEG2000 were prepared. 44% of the phospholipid contained one polyunsaturated acyl chain. Oxidative damage to liposomes after exposure to three different oxidation procedures was measured by the disappearance of polyunsaturated acyl chains, as determined by GC. Oxidation procedures used were: (i) exposure to ionizing γ-irradiation (9200 Gy), for which the grafted PEG2000 provided significant protection against oxidation, with minimal damage to the PEG2000 as determined by 1H NMR and TLC. (ii) Storage for 6 months at 4 °C or for 4 months at 4 °C followed by 4 d at 37 °C, for which the presence of DHP-PEG2000retarded acyl chain peroxidation. (iii) Oxidation of the liposomes by 2,2′-azo(2-amidinopropane) dihydrochloride (a positively charged water-soluble peroxyl radical initiator), for which there was no protection by DHP-PEG2000 (probably due to electrostatic binding of the AAPH to the negatively charged membranes, thereby overriding the hydration layer protection barrier).

Examination of alcoholic solutions of dimethyl acetylphosphonate (1) and dimethyl benzoylphosphonate (2) by 31P NMR spectroscopy reveals the presence of considerable amounts of hemiketals. Because of the great difference between the 31P chemical shifts of acylphosphonates (ca. 0 ppm) and their hemiketals (17–21 ppm), 31P NMR spectroscopy is a uniquely suitable method for studying the rates and equilibria of hemiketal formation of acylphosphonates with different alcohols. The equilibrium constants Kf, K′f (K′f = Kf [ROH]), pseudo-first-order rate constants k′f, the second order rate constants, kf for hemiketal formation from dimethyl acetylphosphonate with various alcohols, as well as the reverse reaction rate constants, kr to starting materials, were determined. The kinetic isotope effect of 2.8 for the forward reaction kf (EtOH addition) and the backward reaction kr indicates a general catalysis pathway. On the other hand, the calculated values of the enthalpies of activation ΔH‡ = 10.37 kcal mol-1 (forward), ΔH‡ = 13.66 kcal mol-1 (backward) and the entropies of activation, ΔS‡ = -17.25 cal mol-1 K-1 (forward), ΔS‡ = -9.82 cal mol-1 K-1 (backward) are not in accord with high molecularity of the reaction (1 cal = 4.184 J). Our analysis led to the conclusion that this is probably due to the fact that the transition state is mainly reactant-like with the development of only limited extent of bond formation. Various plausible reaction pathways for hemiketal formation are discussed. In addition, we have calculated the value of 2.65 σ* for the P(O)(OMe)2 group based on proton affinity obtained from heats of formation (ΔHf) of applying the MNDO techniques. The following linear correlation between pKa values and PA values of hemiketals of the form (Me)(R)C(OH)(OCH2X) was developed: pKa = PA - 356.58 + 9.18 [σ*(Me) + σ*(R) 0.2σ*(X)].

The bacterium Bacillus subtilis produces the DNA integrity scanning protein (DisA), a checkpoint protein that delays sporulation in response to DNA damage. DisA scans the chromosome and pauses at sites of DNA lesions. Structural analysis showed that DisA synthesizes the small molecule cyclic diadenosine monophosphate (c-di-AMP). Here, we demonstrate that the intracellular concentration of c-di-AMP rises markedly at the onset of sporulation in a DisA-dependent manner. Furthermore, exposing sporulating cells to DNA-damaging agents leads to a global decrease in the level of this molecule. This drop was associated with stalled DisA complexes that halt c-di-AMP production and with increased levels of the c-di-AMP-degrading enzyme YybT. Reduced c-di-AMP levels cause a delay in sporulation that can be reversed by external supplementation of the molecule. Thus, c-di-AMP acts as a secondary messenger, coupling DNA integrity with progression of sporulation.

A new series of complexes of the type cis-PtL2X2 [where L is a monodentate AQ-Y(CH2)nNH2 and L2 is a bidentate AQ-Y(CH2)nNH(CH2)2NH2; AQ = anthraquinone, X = Cl, I, Y = NH, O] in which anthraquinone intercalators are tethered to the cis-PtCl2 unit via an (aminoalkyl)amino, (oxyalkyl)amino, or polyethylene glycol (aminoethyl)amino linker chains was prepared and screened in vitro against P388 leukemia. In vivo toxicity studies were carried out on selected complexes. All complexes were characterized by means of elemental analysis, 195Pt NMR spectroscopy, and FTIR. The 1:1 Pt-intercalator complexes displayed much higher in vitro cytotoxic activities than the 1:2 Pt-intercalator complexes. The dichloride complexes were consistently more active than their diiodide counterparts. Among the 1:1 Pt-intercalator complexes those with the shorter linker chains (n = 2, 3) exhibited the highest cytotoxic activities. Three compounds, [[2-[[2-(anthraquinon-1- ylamino)ethyl]amino]ethyl]amine-N,N']dichloroplatinum(II), [[2-[[3-(anthraquinon-1-ylamino)propyl]amino]ethyl]amine- N,N']dichloroplatinum(II), and [[2-[[3-anthraquinon-1- yloxy)propyl]amino]ethyl]amine-N,N']dichloroplatinum(II), were as active in vitro as cisplatin (ED50 = 2-4 x 10(-7) M) while on a molar basis their acute in vivo toxicity was significantly lower than that of cisplatin. In vivo screening against P388 leukemia indicated that these complexes have activity comparable to cisplatin.

The reaction of benzoylphosphonic acid (3) with thionyl chloride leads to the formation of benzoylphosphonic dichloride (5) and P,P′-dibenzoylpyrophosphonic dichloride (6). These products were identified by 31P nmr spectra and through their products of alcoholysis with 2-propanol.

The mode of action of antitumour anthraquinone derivatives (i.e. mitoxantrone) is not clearly established yet. It includes, among others, intercalation and binding to DNA, bioreduction and aerobic redox cycling. A series of anthraquinone derivatives, with potentially bioreducible groups sited in the side chain, have been synthesized and biologically evaluated. Their redox and cytotoxic activities were screened. Derivatives which bear a 2-(dimethylamino)ethylamino substituent, known to confer high DNA affinity, demonstrated cytotoxicity but not redox activity (beside the anthraquinone reduction). Conversely, derivatives which showed redox activity were not cytotoxic toward the P388 cell line. The results suggest that bioreduction is not the main mode of action in the cytotoxicity of anthraquinones.

The reaction of benzoylphosphonic acid (3) with thionyl chloride leads to the formation of benzoylphosphonic dichloride (5) and P,P′-dibenzoylpyrophosphonic dichloride (6). These products were identified by 31P nmr spectra and through their products of alcoholysis with 2-propanol.

Evidence is presented suggesting that hydrogen-bonded base pairing and/or aryl stacking interactions between derivatives of guanine (9-[(4-aminobutyloxy)-methyl]guanine) and cytosine (1-([(2-benzyloxy)ethoxy]methyl)cytosine) lead to enhanced intracomplex chemical reaction between the corresponding amino and ester groups. On the basis of analysis of the kinetic data it is concluded that a chain length of four methylene groups (4-amino- butyloxy as compared to 2-aminoethoxy or 6-aminohexyloxy) on the guanine is necessary to achieve the appropriate geometry for intracomplex reaction. Support for the reaction scheme is provided by the absence of reaction between the guanine derivative and a corresponding ester derivative of thymine, not expected to associate.

Novel methods are described for the preparation of alkyldimethylamine cyanoboranes and β-hydroxylalkyldimethylamine cyanoboranes by C-lithiation of trimethylamine cyanoboranes followed by reaction with alkyl halides, aldehydes, and ketones. Lithiation of the monobromo derivatives of amine cyanoboranes led to the synthesis of the first examples of diborane derivatives of amine cyanoboranes. Bromo derivatives of amine cyanoboranes and amine carboxyboranes have been synthesized by new simple and efficient methods. Amine fluorocyanoboranes and amine fluorocarboxyboranes, new classes of compounds, have been prepared from the bromo precursors by fluorine/bromine exchange using fluorinating reagents such as AgF and Et3N.3HF. Eight different derivatives of oxazaborolidines were synthesized and evaluated for their affect on Streptococcus mutans viability, adhesion, and biofilm formation using 3[H]-thymidine labeled bacteria, and fluorescent stained bacteria. This is the first reported antibacterial activity of this class of compounds. The minimal inhibitory concentration (MIC) values ranged from 0.26 to 10 mM. Structure-activity relationship was observed. The B-butyl moiety of the oxazaborolidines contributed an anti-adhesion effect for all derivatives, while its effect diminished when the boron atom was incorporated in a fused heterocyclic ring. The B-phenyl group induced bacterial adhesion in all tested compounds. In a separate study for boronated saccahrides and enzymatic inhibition, the complex formation between N-butylboronic acid and a series of monosaccharides was investigated by 1H, 13C, and 11B NMR spectroscopy and gas chromatography-mass spectrometry (GC-MS). Then, a series of boronic acid compounds with protease inhibition properties were prepared. The effect of added mono-, di-, and polysaccharides on the inhibitory activity of these compounds was studied. Potassium organotrifluoroborates were found to be reversible competitive inhibitors of α-chymotrypsin and trypsin. Based on 19F NMR, it was speculated that they inactivate the enzymes as a result of the formation of hydrogen bonds between fluorine atoms of the inhibitors and the serine protease.

A series of new amine cyanoborane derivatives were synthesized and exhibited antifungal activity. A long alkyl chain attached to the nitrogen of the amine cyanoboranes and carboxyboranes enhances antifungal activity. An enhanced activity was also obtained upon the halogenation of the amine cyanoboranes as well as in the presence of C=C double bond at the end of the N-alkyl group. The lead compounds were dimethylundecylamine cyanoborane (C 11 H 23 N(CH 3 ) 2 BH 2 CN), 9, and its dibromo derivative dimethylundecylamine dibromocyanoborane (C 11 H 23 N(CH 3 ) 2 BBr 2 CN), 11. The MIC values for the lead compounds against the most important human pathogenic fungi ranged from 16.25 to 32.5 μmol/L and from 10.05 to 79 μmol/ L, respectively. Both compounds were found to be relatively safe in intravenous injections to mice, (MTD = 121.9 and 73.1 μmol/kg, respectively) and active against strains that are resistant to fluconazole (a conventional antifungal medicine). These data indicate their potential to become antifungal agents.

A novel fluorine-18 labeled amine fluorocyanoborane derivative was synthesized from the bromo-derivative precursor in 22% radiochemical yield. The [18F] labeling was accomplished by a semiautomatic method that is based on the synthesis of Ag 18F from Ag2CO3 and H 18F in a platinum dish followed by sonication of the bromo-precursor with Ag 18F in dry benzene to produce [18F] labeled amine fluorocyanoborane which was used with no further purification. A total of 50 microCi of the [18F] labeled amine fluorocyanoborane was injected into normal, female Sprague-Dawley rats (250-300 g) via the tail vein and monitored by Positron emission tomography (PET)/CT to detect its biodistribution in the rat body. The images showed an uptake of this compound in the bones of rats.

C-lithiation of trimethylamine cyanoborane readily occurs with 1.5 equiv of s-BuLi. The C-lithiated complex 1 reacts with various electrophiles such as alkyl iodides, aldehydes, ketones, allyl bromide, and bromotrimethylsilane to give the corresponding products 2−14, in excellent conversion and in good yields. This is the first example of C-lithiation/alkylation of an amine cyanoborane and allows the preparation of amine cyanoboranes not readily available before.

Amidothionophosphates (AMTPs) are a novel group of antioxidants that are lacking in pro-oxidant activity. In this paper, we compare two different amidothionophosphates: 2-hydroxy-ethyl amido, diethyl thionophosphate (AMTP-B), which contains a single primary amido group, and N,N',N-tripropylamidothionophosphate (AMTP-3A), which contains three primary amido groups. The lipoprotein/medium partition coefficients of AMTP-3A and AMTP-B are 74 and 38, respectively. Both protected isolated human low density lipoprotein (LDL) against oxidative damage induced by copper sulfate. Oxidative damage to polyunsaturated acyl chains was determined by gas chromatography (GC), and oxidation kinetics were monitored by following the accumulation of conjugated dienes spectrophotometrically at 234 nm. The AMTP antioxidants significantly protected the LDL against Cu2+-induced oxidation. However, if the LDLs were already partially oxidized, protection against oxidation by the AMTPs was reduced. AMTP-3A was more effective in protecting LDL than was AMTP-B. The difference in antioxidant activity was attributed to the 15-fold higher reactivity of AMTP-3A toward peroxides. Oxidizability of plasma lipoproteins from guinea pigs injected with AMTPs was strongly reduced.

The thermodynamics, pH dependency and solvent effects of the fragmentation reaction of a series of α-oxyiminobenzylphosphonate monomethyl esters [(E)-1a–f] were examined in water and other hydroxylic solvents by UV and by 31P NMR spectroscopy at pH 0–3.1. The fragmentation of compounds (E)-1a–f was found to be a first-order reaction in substrate over the acidity range studied, while the dependence on the acidity is more complex, with rate constants k1 and k2. The ρ values corresponding to the first and second order rate constants were −1.12 and −0.835, respectively, indicating that the reaction is facilitated by electron-donating substituents, which probably enhance the protonation of the oxime OH group. Activation parameters for k1 and k2 reactions were also calculated. The near- zero values of the entropies of activation obtained are consistent with a dissociative transition state with almost no bonding to a nucleophilic solvent. Monitoring the fragmentation reaction of (E)-1a in several binary alcohol–water mixtures at different acidities showed that the reaction rate is enhanced by the alcohol’s acidity and not hampered by the steric requirements of the alcohol molecule. This rules out in our opinion, the likelihood for nucleophilic solvent assistance in the rate-determining step. On the other hand, product studies show that both the nucleophilicity and the steric requirements of the alcohol are of importance in determining the product formed in the fragmentation of (E)-1a. The highest selectivity (S) value was found for MeOH, while S values of

A highly sensitive method for the determination of α-lipoic acid (LA) and dihydrolipoic acid (DHLA) in human plasma and urine has been developed. Samples were acidified and extracted with organic solvent, and the free sulfhydryls of DHLA protected as the dicarboxyethylate by treatment with ethylchloroformate. The free carboxylic function of LA and the SH-protected DHLA were converted into their amide derivatives with the strong fluorophore 2-(4-aminophenyl)-6-methylbenzothiazole in the presence of a coupling agent and a base catalyst. The resulting fluorescent amides of both LA and DHLA were separated on a reversed-phase column (Ultrasphere C 8 ) using simple isocratic elution with acetonitrile–water (80:20) and detected fluorimetrically (excitation 343, emission 423 nm). The method is highly sensitive, reproducible, and is easily applied for the simultaneous determination of LA and DHLA in biological samples.

This study aimed to characterize the effect of polyethylene glycol of 2000 molecular weight (PEG2000) attached to a dialkylphosphatidic acid (dihexadecylphosphatidyl (DHP)-PEG2000) on the hydration and thermodynamic stability of lipid assemblies. Differential scanning calorimetry, densitometry, and ultrasound velocity and absorption measurements were used for thermodynamic and hydrational characterization. Using a differential scanning calorimetry technique we showed that each molecule of PEG2000 binds 136 +/- 4 molecules of water. For PEG2000 covalently attached to the lipid molecules organized in micelles, the water binding increases to 210 +/- 6 water molecules. This demonstrates that the two different structural configurations of the PEG2000, a random coil in the case of the free PEG and a brush in the case of DHP-PEG2000 micelles, differ in their hydration level. Ultrasound absorption changes in liposomes reflect mainly the heterophase fluctuations and packing defects in the lipid bilayer. The PEG-induced excess ultrasound absorption of the lipid bilayer at 7.7 MHz for PEG-lipid concentrations over 5 mol % indicates the increase in the relaxation time of the headgroup rotation due to PEG-PEG interactions. The adiabatic compressibility (calculated from ultrasound velocity and density) of the lipid bilayer of the liposome increases monotonically with PEG-lipid concentration up to approximately 7 mol %, reflecting release of water from the lipid headgroup region. Elimination of this water, induced by grafted PEG, leads to a decrease in bilayer defects and enhanced lateral packing of the phospholipid acyl chains. We assume that the dehydration of the lipid headgroup region in conjunction with the increase of the hydration of the outer layer by grafting PEG in brush configuration are responsible for increasing thermodynamic stability of the liposomes at 5-7 mol % of PEG-lipid. At higher PEG-lipid concentrations, compressibility and partial volume of the lipid phase of the samples decrease. This reflects the increase in hydration of the lipid headgroup region (up to five additional water molecules per lipid molecule for 12 mol % PEG-lipid) and the weakening of the bilayer packing due to the lateral repulsion of PEG chains.

Large unilamellar vesicles (120-160 nm) composed of egg phosphatidylcholine (egg PC) containing approximately 22 wt% of polyunsaturated fatty acids (PUFA) and various mol% (0, 10, 22, or 45) of cholesterol were exposed to oxidative stress. The hydrophilic azo compound 2,2'-azobis-(2-amidinopropane)2HCl (AAPH) which was thermally decomposed to produce a constant flux of peroxy radicals was the source of the oxidative stress (or = 48 h incubation at 37 degrees C). Cholesterol loss following the oxidation was up to 33%, while PUFA were more extensively damaged; loss was up to 52, 88, and 100% for C-18:2, C-20:4, and C-22:6, respectively. (ii) Oxidizability of cholesterol when quantified in absolute amount was three-fold higher when its level was 45 mol%. The interrelationship between bilayer structure, especially its lateral organization and free volume, and lipid peroxidation are discussed. Differential scanning calorimetry of oxidized multilamellar vesicles lacking cholesterol revealed that a high level of oxidative damage to egg phosphatidylcholine PUFA resulted in the loss of the gel to liquid-crystalline phase transition of egg PC (broad peak at around -8 degrees C).

The structure of the title compound reveals the geometry around the boron atom to be tetrahedral, and the BCN moiety has a bent geometry. Copyright © 2005 John Wiley & Sons, Ltd.

The conformation around the boron atom is nearly tetrahedral, with BrBBr bond angles of 109.14(19)° and slightly wider NBC bond angles up to 113.6(3)°. Copyright © 2005 John Wiley & Sons, Ltd.

The effects of ovalbumin (OVA) denaturation using urea, guanidinium chloride (GdnHCl), sodium dodecyl sulphate (SDS), cetylpyridinium chloride (CPC), 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (CHAPS), and 5 different cationic detergents with various side chains, HCl, and CH3COOH were observed. Progressive unfolding in ovalbumin was measured as a function of fluorescent light intensity, peak response and shift in the maximum of emission. Kinetic measurements demonstrated that the rate of denaturation usually followed a double exponential decay pattern, but at small concentrations of urea and acids first-order reaction was indicated. The reversibility of the unfolding-folding transitions was confirmed from tryptophan fluorescence and circular dichroism (CD) measurements. Differences in secondary structure were observed and changes of alpha-helical content were calculated. Polyacrylamide gel electrophoresis (PAGE) with and without sodium dodecyl sulphate (SDS-PAGE) showed differences in the structure of native and denatured ovalbumin. Native protein samples in PAGE demonstrated smaller number and larger mobilities of subunits than denatured ones with different reductants, such as SDS and 2-mercaptoethanol (2 ME). Scanning of SDS protein patterns showed the appearance of aggregated forms in region of 45 kD.

A new series of complexes of the type cis-PtL2X2 [where L is a monodentate AQ-Y(CH2)nNH2 and L2 is a bidentate AQ-Y(CH2)nNH(CH2)2NH2; AQ = anthraquinone, X = Cl, I, Y = NH, O] in which anthraquinone intercalators are tethered to the cis-PtCl2 unit via an (aminoalkyl)amino, (oxyalkyl)amino, or polyethylene glycol (aminoethyl)amino linker chains was prepared and screened in vitro against P388 leukemia. In vivo toxicity studies were carried out on selected complexes. All complexes were characterized by means of elemental analysis, 195Pt NMR spectroscopy, and FTIR. The 1:1 Pt-intercalator complexes displayed much higher in vitro cytotoxic activities than the 1:2 Pt-intercalator complexes. The dichloride complexes were consistently more active than their diiodide counterparts. Among the 1:1 Pt-intercalator complexes those with the shorter linker chains (n = 2, 3) exhibited the highest cytotoxic activities. Three compounds, [[2-[[2-(anthraquinon-1- ylamino)ethyl]amino]ethyl]amine-N,N']dichloroplatinum(II), [[2-[[3-(anthraquinon-1-ylamino)propyl]amino]ethyl]amine- N,N']dichloroplatinum(II), and [[2-[[3-anthraquinon-1- yloxy)propyl]amino]ethyl]amine-N,N']dichloroplatinum(II), were as active in vitro as cisplatin (ED50 = 2-4 x 10(-7) M) while on a molar basis their acute in vivo toxicity was significantly lower than that of cisplatin. In vivo screening against P388 leukemia indicated that these complexes have activity comparable to cisplatin.

The double ionization of salicylhydroxamic acid has been studied. Kinetic and spectrophotometric experiments show that the first dissociation originates from the phenolic OH group, the second dissociation is related to the –CONHOH group.

Anthraquinones, monosubstituted by aminoalkylamino side chains at positions 1, 2 or disubstituted at positions 1, 5 or 1, 8 were prepared. Their in vitro cytotoxic activity ( ED 50 ) was evaluated using: 1) P388 murine leukemia cells and 2) a subline of these cells resistant to doxorubicin (P388/ADR). The results of the structure—activity relationship analysis indicated that monosubstitution in position 1 or 2 showed a decrease of the activity when compared to adryamicin. Disubstitution in positions 1, 5 by N,N -dimethyl ethylenediamine side chain led to optimal activity, whereas the presence of cyclic dialkylamino substituents in the same positions resulted in a corresponding decrease in the anti-tumor activity. Disubstitution in positions 1,8 did not show any improvement in the cytotoxic activity.

Methyl α-(hydroxyimino)benzylphosphonates [(E)-(2) and (Z)-(2)] undergo fragmentation in alcohols to benzonitrile and a (mixed) phosphodiester. Kinetic studies of the behaviour of (E)-(2) and (Z)-(2) in a series of alcohols indicate that (Z)-(2) undergoes acid catalysed isomerization to (E)-(2) which subsequently undergoes fragmentation via a concerted, dissociative bond cleavage to benzonitrile and monomeric methyl metaphosphate (7). The latter is trapped by the solvent in the second step of the reaction to give the final phosphodiester product.

A simple and efficient synthesis of a solid support with a long chain polyamide spacer has been developed. The spacer was made by successive addition of ethylene-diamine and succinic anhydride. The obtained solid support gives very homogeneous 20 mer oligodeoxyribonucleotides, detected by HPLC and electrophoresis.

The effects of cis -diamminedichloroplatinum(II) ( cis -DDP) and a new analog ( cis -DANAP) derived from aminoalkylaminoanthraquinones (RNH(CH 2 ) 3 NH 2 ) 2 PtCl 2 , R = anthraquinone on the oligonucleotide poly(dG)·poly(dC) were studied by electron microscopy. It was observed that with cis -DANAP, the extent of small fragments increased with the increase of the drug/nucleotide molar ratio (Rb) . This effect was not observed with cis -DDP and with the parent aminoalkylaminoanthraquinone free base. The effect was not time dependent and could be observed only at Rb > 0.4. Explanation for this phenomenon was given on the basis of monoadduct formation between the platinum and purine/pyrimidine bases which leads to strand degradation. A salt effect on the length of poly(dG)·poly(dC) is also present.