Synthesis and pharmacological evaluation of (indol-3-yl)alkylamides as potent analgesic agents.

A series of (indol-3-yl)alkylamides was synthesized and evaluated for analgesic activity. Two N-(pyridin-4-yl)acetamides, compounds 24 and 25, bearing benzyl or 4-fluorobenzyl moieties in 1-position of indole ring exhibited promising analgesic properties (ED50 = 8.1 and 11 mg/kg p.o., respectively), being as potent as the reference drugs flupirtine (CAS 56995-20-1), ibuprofen (CAS 15687-27-1) and diclofenac (CAS 15307-86-5). The two test compounds were tested for their anti-inflammatory activity by carrageenin-induced edema in rat paw test. 4-Fluorobenzyl derivative 25 whose ID50 was 0.085 +/- 0.021 mmol/kg was selected as a lead compound for further pharmacomodulation.

D-24851, a novel synthetic microtubule inhibitor, exerts curative antitumoral activity in vivo, shows efficacy toward multidrug-resistant tumor cells, and lacks neurotoxicity.

N-(pyridin-4-yl)-[1-(4-chlorbenzyl)-indol-3-yl]-glyoxyl-amid (D-24851) is a novel synthetic compound that was identified in a cell-based screening assay to discover cytotoxic drugs. D-24851 destabilizes microtubules and blocks cell cycle transition specifically at G2-M phase. The binding site of D-24851 does not overlap with the tubulin binding sites of known microtubule-destabilizing agents like vincristine or colchicine. In vitro, D-24851 has potent cytotoxic activity toward a panel of established human tumor cell lines including SKOV3 ovarian cancer, U87 glioblastoma, and ASPC-1 pancreatic cancer cells. In vivo, oral D-24851 treatment induced complete tumor regressions (cures) in rats bearing Yoshida AH13 sarcomas. Of importance is that the administration of curative doses of D-24851 to the animals revealed no systemic toxicity in terms of body weight loss and neurotoxicity in contrast to the administration of paclitaxel or vincristine. Interestingly, multidrug-resistant cell lines generated by vincristine-driven selection or transfection with the Mr 170,000 P-glycoprotein encoding cDNA were rendered resistant toward paclitaxel, vincristine, or doxorubicin but not towards D-24851 when compared with the parental cells. Because of its synthetic nature, its oral applicability, its potent in vitro and in vivo antitumoral activity, its efficacy against multidrug-resistant tumors, and the lack of neurotoxicity, D-24851 may have significant potential for the treatment of various malignancies.

New N-(pyridin-4-yl)-(indol-3-yl)acetamides and propanamides as antiallergic agents.

A series of new N-(pyridin-4-yl)-(indol-3-yl)alkylamides 44-84 has been prepared in the search of novel antiallergic compounds. Synthesis of the desired ethyl (2-methyindol-3-yl)acetates 1-4 was achieved by indolization under Fischer conditions; Japp-Klingemann method followed by 2-decarboxylation afforded the ethyl (indol-3-yl)alkanoates 17-25. Amidification was successfully carried out by condensation of the corresponding acids or their N-aryl(methyl) derivatives with 4-aminopyridine promoted by 2-chloro-1-methylpyridinium iodide. Efforts to improve the antiallergic potency of the title series by variation of the indole substituents (R1, R2, R) and the length of the alkanoic chain (n = 1, 2, 3) led to the selection of N-(pyridin-4-yl)-[1-(4-fluorobenzyl)indol-3-yl]acetamide 45, out of 41 compounds. This amide was 406-fold more potent than astemizole in the ovalbumin-induced histamine release assay, using guinea pig peritoneal mast cells, with an IC50 = 0.016 microM. Its inhibitory activity in IL-4 production test from Th-2 cells was identical to that of the reference histamine antagonist (IC50 = 8.0 microM) and twice higher in IL-5 assay: IC50 = 1.5 and 3.3 microM, respectively. In vivo antiallergic activity evaluation confirmed efficiency of 45 in sensitized guinea pig late phase eosinophilia inhibition, after parenteral and oral administration at 5 and 30 mg/kg, respectively. Its efficiency in inhibition of microvascular permeability was assessed in two rhinitis models; ovalbumin and capsaicin-induced rhinorrhea could be prevented after topical application of submicromolar concentrations of 45 (IC50 = 0.25 and 0.30 microM); and it also exerted significant inhibitory effect in the first test after iv and oral administration, with ID50 = 0.005 and 0.46 mg/kg.

Polymorphism and desolvation of flupirtine maleate.

Crystallizates of the analgesic agent flupirtine maleate (Katadolon; ASTA Medica, Dresden, Germany) obtained from isopropanol are examined by X-ray diffractometry, polarization microscopy and thermoanalysis. Depending on the crystallizing conditions, the modifications A and B as well as an isopropanol solvate are observed. The inversion temperature A-->B of the enantiotropic modifications is 164 degrees C (differential scanning calorimetry (DSC) onset). During thermal desolvation, modification B is formed well below the inversion temperature. In concentrated isopropanol suspensions, the solvate and modification B are rapidly transformed into modification A. It is shown how phase-pure products consisting of modification A, which is better wettable with water and stable at room temperature, can be obtained.

Synthesis and quantitative structure-activity relationships of anticonvulsant 2,3,6-triaminopyridines.

The synthesis of 2,3,6-triaminopyridine derivatives, representing a unique chemical structure for anticonvulsants, is described. The synthetic program was performed (a) to identify more potent analogs, (b) to determine structural properties controlling potency as well as neurotoxicity, and (c) to reduce the requirements for animal testing. As a result, besides other structural properties, the overall molecular lipophilicity (log k', octanol-coated column) explained changes in anticonvulsant potency and neurotoxicity. Mimicking the interaction of the amphiphilic triaminopyridines with biological membranes, NMR experiments in the presence of lecithin vesicles were conducted in order to measure the phospholipid-binding parameter log delta (1/T2). Replacement of log k' with log delta (1/T2) in the correlation analysis afforded a more significant equation describing the anticonvulsant activity of 21 derivatives.

[New central analgesic-acting triaminopyridines]. / Neue zentralanalgetisch wirksame Triaminopyridine.

New Triaminopyridines with a Central Analgesic Activity 2-Amino-3-((prop-1-en-3-yl)oxycarbonylamino)-6-(4-fluorobenzyla mino) pyridine hydrochloride (D-19050) is a centrally and peripherally acting analgesic with rapid onset, long duration of action and a good therapeutic range. D-19050 can be obtained in a 5-step-synthesis starting from 2,6-dichloropyridine.

[Synthesis and structure of new basic enol ethers]. / Synthese und Struktur neuartiger basischer Enolether.

Synthesis of new basic enol ethers with valuable pharmacological properties is described. The structure of these compounds is elucidated by 1H- and 13C-NMR-spectroscopy; the stereochemistry of the double bond is determined by use of the intramolecular nuclear Overhauser effect. An X-ray analysis of an isolated diastereomer confirms the proposed constitution.