Anti-Alzheimer's multitarget-directed ligands with serotonin 5-HT6 antagonist, butyrylcholinesterase inhibitory, and antioxidant activity.

Serotonin 5-HT6 receptors, butyrylcholinesterase (BuChE) and oxidative stress are related to the pathophysiology of Alzheimer's disease. Inhibition of BuChE provides symptomatic treatment of the disease and the same effect was demonstrated for 5-HT 6 antagonists in clinical trials. Oxidative stress is regarded as a major and primary factor contributing to the development of Alzheimer's disease; therefore, antioxidant agents may provide a disease-modifying effect. Combining BuChE inhibition, 5-HT 6 antagonism, and antioxidant properties may result in multitarget-directed ligands providing cognition-enhancing properties with neuroprotective activity. On the basis of the screening of the library of 5-HT 6 antagonists against BuChE, we selected two compounds and designed their structural modifications that could lead to improved BuChE inhibitory activity. We synthesized two series of compounds and tested their affinity and functional activity at 5-HT 6 receptors, BuChE inhibitory activity and antioxidant properties. Compound 12 with K i and K b values against 5-HT 6 receptors of 41.8 and 74 nM, respectively, an IC 50 value of 5 µM against BuChE and antioxidant properties exceeding the activity of ascorbic acid is a promising lead structure for further development of anti-Alzheimer's agents.

Melamine induces autophagy in mesangial cells via enhancing ROS level.

CONTEXT: Melamine, as an industrial chemical, was blended illegally with infant formula to counterfeit the illusion of more abundant protein content in 2008. Due to its nephrotoxicity, thousands of children underwent kidney disease. OBJECTIVE: It was to investigate whether melamine could affect autophagy in mesangial cells (MCs) via oxidative stress and whether autophagy played a positive role in protecting MCs impaired by melamine. MATERIALS AND METHODS: MCs were used as a mesangium model. The cell viability was measured by MTT assay. Intracellular hydrogen peroxide (H2O2) was assessed by using H2O2 assay kit. The Western blot assay was employed to measure the expression of autophagy-related proteins. RESULTS: MTT assay showed that melamine induced MCs death in a concentration-dependent and time-dependent manner. The measurement of H2O2 demonstrated that melamine decreases H2O2 level of MCs. Meaningfully, treatment of a type of ROS scavenger formulation named N-(mercaptopropionyl)-glycine (N-MPG) could inhibit MCs death induced by melamine. Meanwhile, Western blot analysis indicated that melamine enhanced the ratio of LC3-II/LC3-I and Beclin-1 level in MCs, and N-MPG down-regulated autophagy in melamine-treated MCs. The cell viability of MCs with melamine and an autophagy inhibitor named 3-methyladenine (3-MA) showed that autophagy could protect melamine-treated MCs. CONCLUSIONS: The study showed that melamine-enhanced autophagy by increasing ROS levels in MCs, and autophagy could protect melamine-treated MCs. Improving autophagy may become a new potential clinical application to relieve melamine-induced renal injury.

Monitoring of explosive residues in lake-bottom water using Polar Organic Chemical Integrative Sampler (POCIS) and chemcatcher: determination of transfer kinetics through Polyethersulfone (PES) membrane is crucial.

Between 1920 and 1967, approximatively 8200 tons of ammunition waste were dumped into some Swiss lakes. This study is part of the extensive historical and technical investigations performed since 1995 by Swiss authorities to provide a risk assessment. It aims to assess whether explosive monitoring by passive sampling is feasible in lake-bottom waters. Polar organic chemical integrative sampler (POCIS) and Chemcatcher were first calibrated in a channel system supplied with continuously refreshed lake water spiked with two nitroamines (HMX and RDX), one nitrate ester (PETN), and six nitroaromatics (including TNT). Exposure parameters were kept as close as possible to the ones expected at the bottom of two affected lakes. Sixteen POCIS and Chemcatcher were simultaneously deployed in the channel system and removed in duplicates at 8 different intervals over 21 days. Sorbents and polyethersulfone (PES) membranes were separately extracted and analyzed by UPLC-MS/MS. When possible, a three-compartment model was used to describe the uptake of compounds from water, over the PES membrane into the sorbent. Uptake of target compounds by sorbents was shown not to approach equilibrium during 21 days. However, nitroaromatics strongly accumulated in PES, thus delaying the transfer of these compounds to sorbents (lag-phase up to 9 days). Whereas sampling rate (RS) of nitroamines were in the range of 0.06-0.14 L day-1, RS of nitroaromatics were up to 10 times lower. As nitroaromatic accumulation in PES was integrative over 21 days, PES was used as receiving phase for these compounds. The samplers were then deployed at lake bottoms. To ensure that exposure conditions were similar between calibration and field experiments, low-density polyethylene strips spiked with performance reference compounds were co-deployed in both experiments and dissipation data were compared. Integrative concentrations of explosives measured in the lakes confirmed results obtained by previous studies based on grab sampling.

Basis for antagonism by sodium bentazon of tritosulfuron toxicity to white bean (Phaseolus vulgaris L.).

White bean (Phaseolus vulgaris L.) was used to study the antagonism caused by Na-bentazon on the phytotoxic action of the sulfonylurea (SU) herbicide tritosulfuron. After 168 h, uptake and translocation of [14C]tritosulfuron were reduced by 60 and 89%, respectively, when Na-bentazon was added to the mixture. Addition of (NH4)2SO4 or replacement of Na-bentazon with NH4-bentazon completely eliminated the negative effects on [14C]tritosulfuron uptake but not on its translocation. Scanning electron microscopy revealed that a mixture of Na-bentazon plus tritosulfuron plus DASH HC (0.156%) formed a rough layer of grain-like crystals on the leaf surface, whereas the addition of (NH4)2SO4 or replacement of Na-bentazon with NH4-bentazon resulted in amorphous deposits that may be more easily absorbed. The antagonism of tritosulfuron's phytotoxicity by Na-bentazon involves two separate processes, chemical (uptake effect) and biochemical (translocation effect).

Synthesis and in vivo validation of [O-methyl-11C]2-{4-[4-(7-methoxynaphthalen-1-yl)piperazin- 1-yl]butyl}-4-methyl-2H-[1,2,4]triazine-3,5-dione: a novel 5-HT1A receptor agonist positron emission tomography ligand.

Antagonist 5-HT(1A) PET ligands are available, but an agonist ligand would give more information about signal transduction capacity. Synthesis and in vivo evaluation of [O-methyl-(11)C]2-{4-[4-(7-methoxynaphthalen-1-yl)piperazin-1-yl]butyl}-4-methyl-2H-[1,2,4]triazine-3,5-dione (10), a potential high affinity (K(i) = 1.36 nM) 5-HT(1A) agonist PET tracer is described. Piperazine 10 is a 5-HT(1A) agonist with an EC(50) comparable to serotonin, based on cAMP formation and GTP(gamma)S binding assays. Radiosynthesis of [(11)C]10 has been achieved by reacting 2-{4-[4-(7-hydroxynaphthalen-1-yl)piperazin-1-yl]butyl}-4-methyl-2H-[1,2,4]triazine-3,5-dione (9) and [(11)C]CH(3)OTf in 25 +/- 5% (n = 15) yield at the end of synthesis (EOS). The chemical and radiochemical purities of [(11)C]10 were >99% with a specific activity 1500 +/- 300 Ci/mmol (n =15). PET studies in anesthetized baboon demonstrate [(11)C]10 specific binding in brain regions rich in 5-HT(1A) receptors. Binding of [(11)C]10 was blocked by WAY100635 and 8-OH-DPAT. The regional brain volumes of distribution (V(T)) of [(11)C]10 in baboon correlate with [(11)C]WAY100635 V(T) in baboons. These data provide evidence that [(11)C]10 is the first promising agonist PET tracer for the 5-HT(1A) receptors.

Induction of wheat and maize glutathione S-transferase by some herbicide safeners and their effect on enzyme activity against butachlor and terbuthylazine.

The expression of glutathione S-transferase (GST) activity in wheat and maize shoots was investigated in response to treatments with the herbicide safeners benoxacor, cloquintocet-mexyl, fenchlorazole-ethyl, fenclorim, fluxofenim and oxabetrinil. These safeners significantly enhanced the GST activity towards 1-chloro-2,4-dinitrobenzene (CDNB) as a 'standard' substrate, with the exception of oxabetrinil in maize. The enhancements of GST (CDNB) activity were found to be concomitant with increases in V(max) (the reaction rate when the enzyme is fully saturated by the substrate) in wheat following cloquintocet-mexyl and fenchlorazole-ethyl treatments, and in maize following fenchlorazole-ethyl treatment. Otherwise, decreases in V(max) were observed in wheat and maize following fenclorim and fluxofenim treatments. With the exception of oxabetrinil, all the safeners significantly reduced the apparent K(M) (the substrate concentration required for 50% of maximum GST activity) of both wheat and maize GST. The V(max) and K(M) variations following safener treatments are discussed in terms of an increased expression of GST enzymes and an increased affinity for the CDNB substrate. The activity of wheat and maize GST was also assayed towards butachlor and terbuthylazine respectively; the results indicate the ability of cloquintocet-mexyl, fenchlorazole-ethyl and fluxofenim to enhance the enzyme activity in wheat and of benoxacor and fenchlorazole-ethyl to do so in maize.

Focus on small molecule inhibitors for treatment of inflammatory and autoimmune diseases.

The 228th American Chemical Society (ACS) National Meeting was held August 22-26, 2004, in Philadelphia, Pennsylvania. More than 400 medicinal chemistry papers were presented, most in symposia, general sessions and poster sessions sponsored by the ACS Division of Medicinal Chemistry. One major focus of the meeting was the development of novel drugs for the treatment of inflammatory and autoimmune diseases such as rheumatoid arthritis, asthma, inflammatory bowel disease (Crohn's disease), psoriasis, reperfusion injury and endotoxic shock. This report will center on said areas of research.

Investigation for the characteristic anticoccidial activity of diclazuril in battery trials.

To clarify the character of the anticoccidial activity of diclazuril a series of battery trials was conducted. Diclazuril showed excellent anticoccidial activity in the infection of chickens with Eimeria tenella, E. necatrix or E. acervulina at the feeding level of 0.1 ppm. When diclazuril was administered in combination with a nucleic acid precursor, uracil, uridine, orotate or orotidine, the reduction of the activity of diclazuril to the infections induced by above species was not observed. While, bloody droppings with severe cecal lesions were resulted, when diclazuril was administered in combination with uridine 5(1)-diphosphoglucose (UDPG) or its N-acetyl amine (UDPGNAC) to chickens infected with E. tenella. While, body weight gain of the birds and oocyst output was not affected by these combination-treatment. Results demonstrated that the antagonistic effect of UDPG and UDPGNAC to diclazuril was partial. The possibility of the cross resistance between diclazuril and 6-azauracil (AzU) in E. tenella was investigated using two populations induced resistance to AzU or diclazuril. The results demonstrated that the cross resistance does not exist between AzU and diclazuril, indicating that the mode of action of each drug is different.

Effect of folate derivatives on the activity of antifolate drugs used against malaria and cancer.

The folate derivatives folic acid (FA) and folinic acid (FNA) decrease the in vivo and in vitro activities of antifolate drugs in Plasmodium falciparum. However, the effects of 5-methyl-tetrahydrofolate (5-Me-THF) and tetrahydrofolate (THF), the two dominant circulating folate forms in humans, have not been explored yet. We have investigated the effects of FA, FNA, 5-Me-THF, and THF on the in vitro activity of the antimalarial antifolates pyrimethamine and chlorcycloguanil and the anticancer antifolates methotrexate (MTX), aminopterin, and trimetrexate (TMX), against P. falciparum. The results indicate that these anticancers are potent against P. falciparum, with IC50 < 50 nM. 5-Me-THF does not significantly decrease the activity of all tested drugs, and none of the tested folate derivatives significantly decrease the activity of these anticancers. Thus, malaria folate metabolism has features different from those in human, and the exploitation of this difference could lead to the discovery of new drugs to treat malaria. For instance, the combination of 5-Me-THF with a low dose of TMX could be used to treat malaria. In addition, the safety of a low dose of MTX in the treatment of arthritis indicates that this drug could be used alone to treat malaria.

Spirulina maxima pretreatment partially protects against 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine neurotoxicity.

Spirulina is an alga that has a high nutritional value and some of its biological activities are attributed to the presence of antioxidants. Oxidative stress is involved in Parkinson's disease. This study aims at evaluating the neuroprotective role of Spirulina maxima (Sp.) against 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) neurotoxicity, used as a model of Parkinson's disease. Ninety-six male C-57 black mice were pretreated with Spirulina for 14 days (25, 50, 100, 150 or 200 mg/kg, oral), followed by three MPTP administrations (30 mg/kg, intraperitoneal, i.p.). Animals were given Sp. for 8 additional days. After the treatment, the striatal dopamine (DA) content was analysed by high performance liquid chromatography, and lipid peroxidation was studied as an index of oxidative stress. Sp. pretreatment at 150 mg/kg partially prevented (51%) the DA-depleting effect of MPTP and blocked oxidative stress. Spirulina partially prevents MPTP neurotoxicity and oxidative stress, suggesting it could be a possible alternative in experimental therapy.

Specific triazine resistance in bacterial reaction centers induced by a single mutation in the QA protein pocket.

We report here the first example of a reaction center mutant from Rhodobacter sphaeroides, where a single mutation (M266His --> Leu) taking place in the primary quinone protein pocket confers selective resistance to triazine-type inhibitors (terbutryn, ametryn, and atrazine), which bind in the secondary quinone protein pocket, at about 13 A from the mutation site. The M266His --> Leu mutation involves one of the iron atom ligands. Interestingly, neither the secondary quinone nor the highly specific inhibitor stigmatellin binding affinities are affected by the mutation. It is noticeable that in the M266His --> Ala mutant a nativelike behavior in observed. We suggest that the long side chain of Leu in position M266 may lack space to accommodate in the Q(A) pocket therefore transferring its hindrance to the Q(B) pocket. This may occur via the structural feature formed by the Q(A)-M219His-Fe-L190His-inhibitor (or Q(B)) connection, pushing L189Leu and/or L229Ile in closer contact to the triazine molecules, therefore decreasing their bindings. This opens the possibility to finely tune, in reaction center proteins, the affinity for herbicides by designing mutations distant from their binding sites.

Dissociation between renal medullary PGE2-synthesis and urine PGE2-excretion. Antagonism by bumetanide of chlorazanil induced urine PGE2-excretion in rats.

Normal conscious female Sprague-Dawley rats were treated with chlorazanil (3 mg/kg i.p.), and urine was collected for 3 hours. Urine prostaglandin E2-excretion increased from 25 +/- 3 to 271 +/- 32 ng/kg/3 h. The enhancement of urine PGE2-excretion was inhibited by pretreatment with bumetanide (75 mg/kg p.o.). In separate experiments the papillary quantity of PGE2 was determined in freshly homogenized tissue. The basal level (14 +/- 2 ng PGE2/papilla) was increased by chlorazanil to 51 +/- 11 ng PGE2/papilla and 24 +/- 7 ng PGE2/papilla at one and two hours respectively after drug administration. The capacity of chlorazanil to increase medullary PGE2 accumulation was unaffected by bumetanide pretreatment. The results show that bumetanide dissociated the medullary PGE2 level from the excretion of PGE2 in urine, when the former was elevated by chlorazanil.

Effect of the PAF-antagonist WEB 2086 on anaphylactic lung reaction: comparison of inhalative and intravenous challenge.

The specific and potent antagonist of platelet activating factor (PAF), WEB 2086, has been used to investigate the putative role of PAF in anaphylaxis in the guinea-pig. Intravenous (i.v.) challenge with ovalbumin has been compared to inhalative provocation. When actively sensitized guinea-pigs were challenged by the i.v. route, in the presence of mepyramine (5 micrograms/kg i.v.), oral WEB 2086 (0.05-0.5 mg/kg) inhibited the anaphylactic bronchoconstriction but not the hypotension. In passively sensitized guinea-pigs, i.v. WEB 2086, in the presence of mepyramine, protected the animals from both anaphylactic bronchoconstriction and blood pressure changes. When the antigen was inhaled by actively sensitized guinea-pigs, WEB 2086 inhibited the anaphylactic reaction without the administration of any additional antihistamine. These results suggest that PAF plays an important role in anaphylaxis. PAF may be (a) more important in passive than in active anaphylaxis and (b) may be involved during inhalative challenge in active anaphylaxis.

Adenosine A1 receptor-mediated antiadrenergic effects are modulated by A2a receptor activation in rat heart.

Presently, the physiological significance of myocardial adenosine A2a receptor stimulation is unclear. In this study, the influence of adenosine A2a receptor activation on A1 receptor-mediated antiadrenergic actions was studied using constant-flow perfused rat hearts and isolated rat ventricular myocytes. In isolated perfused hearts, the selective A2a receptor antagonists 8-(3-chlorostyryl)caffeine (CSC) and 4-(2-[7-amino-2-(2-furyl)[1,2, 4]triazolo[2,3-a][1,3,5]triazin-5-ylamino]ethyl)phenol (ZM-241385) potentiated adenosine-mediated decreases in isoproterenol (Iso; 10(-8) M)-elicited contractile responses (+dP/dtmax) in a dose-dependent manner. The effect of ZM-241385 on adenosine-induced antiadrenergic actions was abolished by the selective A1 receptor antagonist 1,3-dipropyl-8-cyclopentylxanthine (10(-7) M), but not the selective A3 receptor antagonist 3-ethyl-5-benzyl-2-methyl-4-phenylethynyl-6-phenyl-1, 4-(+/-)-dihydropyridine-3,5-dicarboxylate (MRS-1191, 10(-7) M). The A2a receptor agonist carboxyethylphenethyl-aminoethyl-carboxyamido-adenosine (CGS-21680) at 10(-5) M attenuated the antiadrenergic effect of the selective A1 receptor agonist 2-chloro-N6-cyclopentyladenosine (CCPA), whereas CSC did not influence the antiadrenergic action of this agonist. In isolated ventricular myocytes, CSC potentiated the inhibitory action of adenosine on Iso (2 x 10(-7) M)-elicited increases in intracellular Ca2+ concentration ([Ca2+]i) transients but did not influence Iso-induced changes in [Ca2+]i transients in the absence of exogenous adenosine. These results indicate that adenosine A2a receptor antagonists enhance A1-receptor-induced antiadrenergic responses and that A2a receptor agonists attenuate (albeit to a modest degree) the antiadrenergic actions of A1 receptor activation. In conclusion, the data in this study support the notion that an important physiological role of A2a receptors in the normal mammalian myocardium is to reduce A1 receptor-mediated antiadrenergic actions.

Nicotine diminishes anticonvulsant activity of antiepileptic drugs in mice.

Nicotine administered acutely at subconvulsive dose of 4 mg/kg, significantly decreased the protective activity of valproate, carbamazepine, diphenylhydantoin, phenobarbital, topiramate and lamotrigine against maximal electroshock-induced tonic convulsions in mice. The obtained data may suggest that interaction between nicotine and antiepileptic drugs should be carefully considered as a cause of the therapeutic failure in epileptic patients.