The influence of 5-HT(2A) activity on a 5-HT(2C) specific in vivo assay used for early identification of multiple acting SERT and 5-HT(2C) receptor ligands.

As a result of our exploratory programme aimed at elaborating dually acting compounds towards the serotonin (5-HT) transporter (SERT) and the 5-HT2C receptor a novel series of 3-amino-1-phenylpropoxy substituted diphenylureas was identified. From that collection two promising compounds (2 and 3) exhibiting highest 5-HT2C receptor affinity strongly inhibited the 5-HT2C receptor agonist 1-(3-chlorophenyl)piperazine (mCPP) induced hypomotility in mice. In further pursuance of that objective (2-aminoethyl)(benzyl)sulfamoyl diphenylureas and diphenylpiperazines have also been elaborated. Herein we report the synthesis of potent multiple-acting compounds from this new class. However, when two optimized representatives (6 and 14) possessing the desired in vitro profile were tested neither reduced the motor activity of mCPP treated animals. Comparative albeit limited in vitro structure-activity relationship (SAR) analysis and detailed in vivo studies are discussed and explanation for their intricate behaviour is proposed.

Design of novel multiple-acting ligands towards SERT and 5-HT2C receptors.

This Letter describes our attempts to elaborate dually acting compounds possessing serotonin re-uptake transporter inhibitor and serotonin 5-HT2C receptor antagonist properties. A novel series of 1,3-diphenylureas and N-phenylbenzamides have thus been prepared and evaluated. Based on its in vitro and in vivo activities, as well as pharmacokinetic profile, compound 16a was identified as a lead compound. The synthesis and structure-activity relationship of this series of compounds is presented herein.

Discovery of cariprazine (RGH-188): a novel antipsychotic acting on dopamine D3/D2 receptors.

Medicinal chemistry optimization of an impurity isolated during the scale-up synthesis of a pyridylsulfonamide type dopamine D(3)/D(2) compound (1) led to a series of new piperazine derivatives having affinity to both dopamine D(3) and D(2) receptors. Several members of this group showed excellent pharmacokinetic and pharmacodynamic properties as demonstrated by outstanding activities in different antipsychotic tests. The most promising representative, 2m (cariprazine) had good absorption, excellent brain penetration and advantageous safety profile. Based on its successful clinical development we are looking forward to the NDA filing of cariprazine in 2012.

Discovery of novel histamine H4 and serotonin transporter ligands using the topological feature tree descriptor.

Ligand-based approaches are particularly important in the hit identification process of drug discovery when no structural information on the target is available. Pharmacophore descriptors that use a topological representation of the ligands are usually fast enough to screen large compound libraries effectively when seeking novel lead candidates. One example of this kind is the Feature Tree descriptor, a reduced graph representation implemented in the FTrees software. In this study, we tested the screening efficiency of FTrees by both retrospective and prospective screens using known histamine H4 antagonists and serotonin transporter (SERT) inhibitors as query molecules. Our results demonstrate that FTrees can effectively find actives. Particularly when combined with a subsequent 2D fingerprint-based diversity selection, FTrees was found to be extremely effective at discovering a diverse set of scaffolds. Prospective screening of our in-house compound deck provided several novel H4 and SERT ligands that could serve as suitable starting points for further optimization.

Inhibition of lipid peroxidation of herbal extracts (obtained from plant drug mixtures of Myrtilli folium, Phaseoli fructus sine seminibus and Salviae folium) used in type 2 diabetes mellitus.

Plant drug mixtures are widely used in the adjuvant therapy of type 2 diabetes mellitus for the prevention of complications. The drug mixtures generally contribute to the efficiency of the therapy and may also reduce undesirable side effects. Two herbal extracts (lyophilized aqueous extracts of plant drug mixtures 1: Myrtilli folium, Phaseoli fructus sine seminibus and 2: Myrtilli folium, Phaseoli fructus sine seminibus, Salviae folium) were investigated in in vitro rat models. The content of bioactive constituents (polyphenol, flavonoid and vitamin C) in plant drug mixtures and lyophilized samples was evaluated. The antioxidant activity of lyophilized extracts was determined by measuring the ferric reducing ability of the plant, Fe2+ induced lipid peroxidation (LPO) in rat brain homogenates and NADPH (beta-nicotinamide adenine dinucleotide phosphate reduced form) induced LPO in cerebral microsomes. The antioxidant activity of lyophilized extracts was compared to that of quercetin and rutin. Both teas of lyophilized extracts had significant reducing ability (2694 and 2771 micromol/l) and inhibited LPO (IC50 28.0 and 20.6 microl in NADPH induced LPO, 17.3 and 8.7 microl in Fe2+ induced LPO). The high concentration of polyphenol/flavonoid (12.38-13.00 and 1.45-5.22 g/100 g, respectively) and vitamin C (0.099-0.165 g/100 g) in the herbal extracts is related to their significant antioxidant properties. The tea mixtures have significant nutritional value, since the consumption of 2 or 3 cups of tea a day covers 50% of the daily requirement of vitamin C and it is also relevant polyphenol source. The high polyphenol/flavonoid content may restore the redox imbalance and contribute to the prevention of diabetic complications.

Comparative pharmacology of adrenergic alpha(2C) receptors coupled to Ca(2+) signaling through different Galpha proteins.

Adrenergic alpha(1), alpha(2) and beta receptors are members of the G-protein-coupled receptor families (GPCRs) mediating physiological responses to adrenaline (epinephrine) and noradrenaline (norepinephrine). Since GPCRs are major targets for potential therapeutic agents, development of robust, reliable and cost effective functional screening methods for these receptors is in the focus of pharmacological research. For this reason, the aim of the present study was to develop an intracellular calcium assay for investigating the pharmacology of the alpha(2C) type of adrenergic receptors (alpha(2C)-AR). Although activation of alpha(2C)-AR is not linked to calcium mobilization, co-expression of these receptors with the chimeric Galpha(qi5) protein, containing the five carboxyl-terminal amino acids from G(i), or promiscuosus Galpha(16) protein can divert receptor signaling to the G(q) pathway generating Ca(2+) release from intracellular stores. In order to assess the functional potency of alpha(2)-AR agonists and antagonists, we established a fluorometric Ca(2+) assay using cell lines stably and constitutively co-expressing alpha(2C)-AR and Galpha(qi5) or Galpha(16) proteins (Galpha(qi5)/alpha(2C) and Galpha(16)/alpha(2C)). As part of the pharmacological characterization, we measured the changes in cytoplasmic Ca(2+) levels due to activation of the chimeric Galpha(qi5) or Galpha(16) coupled recombinant alpha(2C) receptors as a function of increasing concentration of several agonists (noradrenaline, brimonidine, oxymetazoline, clonidine, moxonidine) and antagonists (MK912, yohimbine). The binding affinities of alpha(2)-AR agonist and antagonists and the inhibition of the forskolin-stimulated cAMP accumulation in alpha(2C)-AR expressing cells were also measured. These results confirmed that the Galpha(qi5)/alpha(2C) and Galpha(16)/alpha(2C) recombinant systems can be useful for modelling the native G(i)-coupled system. Our results indicate that a plate-reader based fluorometric Ca(2+) assay may be suitable in high-throughput screening for alpha(2C)-AR ligands as well.

Chemical and biological investigation of N-hydroxy-valdecoxib: An active metabolite of valdecoxib.

The inhibition of cyclooxygenase enzymes plays an important role in the treatment of inflammatory diseases. N-Hydroxy-4-(5-methyl-3-phenylisoxazol-4-yl)benzenesulfonamide (3)-a primary metabolite of the highly selective COX-2 inhibitor valdecoxib-was synthesized and stabilized as its monohydrate (3a.H(2)O). The anti-inflammatory properties of 3a.H(2)O were investigated in carrageenan-induced edema and in acute and chronic pain models. Based on our biological investigation, we conclude that N-hydroxy-valdecoxib 3a is an active metabolite of valdecoxib.

Synthesis and evaluation of 2'-hydroxyethyl trans-apovincaminate derivatives as antioxidant and cognitive enhancer agents.

A series of trans-2'-hydroxyethyl and 2'-acyloxyethyl apovincaminates 4b- f and 7b- f has been synthesized and evaluated for their antioxidant and antiamnesic effects. The new esters were prepared from 4a and 7a ethyl esters or from the corresponding carboxylic acid sodium salt. For starting materials 11a, b, a new stereoselective trans-reduction was elaborated. From the combined results of the data obtained from in vitro and in vivo tests and examination of the metabolism, (3 R,16 S)-2'-hydroxyethyl apovincaminate ( 7b, RGH-10885) was identified as the most promising compound, owing to its potent neuroprotective and antiamnesic activities. The in vivo effectiveness of selected compounds on the cognitive functions was studied in a one-trial passive avoidance task and a water-labyrinth test.

Selective NR1/2B N-methyl-D-aspartate receptor antagonists among indole-2-carboxamides and benzimidazole-2-carboxamides.

(4-Benzylpiperidine-1-yl)-(6-hydroxy-1H-indole-2-yl)-methanone (6a) derived from (E)-1-(4-benzylpiperidin-1-yl)-3-(4-hydroxy-phenyl)-propenone (5) was identified as a potent NR2B subunit-selective antagonist of the NMDA receptor. To establish the structure-activity relationship (SAR) and to attempt the improvement of the ADME properties of the lead, a series of compounds were prepared and tested. Several derivatives showed low nanomolar activity both in the binding and in the functional assay. In a formalin-induced hyperalgesia model in mice, 6a and (4-benzylpiperidine-1-yl)-[5(6)-hydroxy-1H-benzimidazol-2-yl]-methanone (60a) were as active as besonprodil (2) after oral administration. A CoMSIA model was developed based on binding data of a series of indole- and benzimidazole-2-carboxamides.

Kynurenic acid amides as novel NR2B selective NMDA receptor antagonists.

A novel series of kynurenic acid amides, ring-enlarged derivatives of indole-2-carboxamides, was prepared and identified as in vivo active NR2B subtype selective NMDA receptor antagonists. The synthesis and SAR studies are discussed.

Benzimidazole-2-carboxamides as novel NR2B selective NMDA receptor antagonists.

A novel series of benzimidazole-2-carboxamide derivatives was prepared and identified as NR2B selective NMDA receptor antagonists. The influence of some structural elements, like H-bond donor groups placed on the benzimidazole skeleton and the substitution pattern of the piperidine ring, on the biological activity was studied. Compound 6a showed excellent analgetic activity in the mouse formalin test following po administration.

Tolperisone-type drugs inhibit spinal reflexes via blockade of voltage-gated sodium and calcium channels.

The spinal reflex depressant mechanism of tolperisone and some of its structural analogs with central muscle relaxant action was investigated. Tolperisone (50-400 microM), eperisone, lanperisone, inaperisone, and silperisone (25-200 microM) dose dependently depressed the ventral root potential of isolated hemisected spinal cord of 6-day-old rats. The local anesthetic lidocaine (100-800 microM) produced qualitatively similar depression of spinal functions in the hemicord preparation, whereas its blocking effect on afferent nerve conduction was clearly stronger. In vivo, tolperisone and silperisone as well as lidocaine (10 mg/kg intravenously) depressed ventral root reflexes and excitability of motoneurons. However, in contrast with lidocaine, the muscle relaxant drugs seemed to have a more pronounced action on the synaptic responses than on the excitability of motoneurons. Whole-cell measurements in dorsal root ganglion cells revealed that tolperisone and silperisone depressed voltage-gated sodium channel conductance at concentrations that inhibited spinal reflexes. Results obtained with tolperisone and its analogs in the [3H]batrachotoxinin A 20-alpha-benzoate binding in cortical neurons and in a fluorimetric membrane potential assay in cerebellar neurons further supported the view that blockade of sodium channels may be a major component of the action of tolperisone-type centrally acting muscle relaxant drugs. Furthermore, tolperisone, eperisone, and especially silperisone had a marked effect on voltage-gated calcium channels, whereas calcium currents were hardly influenced by lidocaine. These data suggest that tolperisone-type muscle relaxants exert their spinal reflex inhibitory action predominantly via a presynaptic inhibition of the transmitter release from the primary afferent endings via a combined action on voltage-gated sodium and calcium channels.

Nitrone derivatives of trolox as neuroprotective agents.

Synthesis of nitrone derivatives of trolox is described. Their biological evaluation was performed in vitro for scavenging different free radicals, inhibiting Fe(2+)-induced lipid peroxidation, and in vivo in a permanent middle cerebral artery occlusion model in mice. New compounds exert pharmacological activities comparable to or better than those of trolox or nitrone-type reference compounds.

Oxamides as novel NR2B selective NMDA receptor antagonists.

A novel series of oxamides derived from indole-2-carboxamides was identified as potent NR2B selective NMDA receptor antagonists. Several members of this group showed good analgesic activity in the mouse formalin test.

Synthesis and studies of 1,2-dihydroquinoline derivatives as inhibitors of lipid peroxidation.

A series of new spiro[naphto[2,1-c][2,7]naphtiridine-5,4'-piperidine] derivatives was prepared. Biochemical investigations revealed that all members of this series were potent inhibitors of both NADPH- and Fe(2+)-dependent lipid peroxidation (IC50 < 10 mumol/l) in rat brain microsomes and rat brain homogenate, respectively.

Indole-2-carboxamides as novel NR2B selective NMDA receptor antagonists.

A novel series of indole-2-carboxamide derivatives was prepared and identified as NR2B selective NMDA receptor antagonists. The influence of the number and position of OH groups on the indole skeleton as well as the substitution of the piperidine ring on the biological activity of the compounds was studied.

Effect of different metal ions on the oxidative damage and antioxidant capacity of hyaluronic acid.

Degradation and the antioxidative effect of Na-, Zn-, Co-, Cu-, and Mn-hyaluronic acid (HA) associates were studied. Our findings revealed the protective effect of certain counterions against ROS-induced HA degradation. We could also separate the antioxidative effect of certain counterions from that of the HA by examining the effect of the counterions in their free ionic forms. The result showed that metal ions with altering oxidative status (Co(2+), Cu(2+), Mn(2+)) proved to be effective in themselves or their effect added to that of HA when HA was also effective. Moreover, the effects of Co-HA against z.rad;O(2)(-) and of Mn-HA against ONOO(-) as well as the synergic effect of Zn-HA associates where Zn(2+) is of fixed oxidative status were attributed to the structure-stabilizing complex formed between certain counterions and HA. Our examination also concerned the influence of HA associates on the indirect antioxidation related to Fe(2+) chelating. The individual effects of Zn(2+), Co(2+), and Cu(2+) were only detectable, which could be explained by the competitive displacement of ferrous from its binding site.