Synthesis and structure-activity relationship of novel lactam-fused chroman derivatives having dual affinity at the 5-HT(1A) receptor and the serotonin transporter.

The structure-activity relationship (SAR) for three series of lactam-fused chroman derivatives possessing 3-amino substituents was evaluated. Many compounds exhibited affinities for both the 5-HT(1A) receptor and the 5-HT transporter. Compounds 45 and 53 demonstrated 5-HT(1A) antagonist activities in the in vitro cAMP turnover model.

Normal-phase automated mass-directed HPLC purification of a pyrrolobenzodiazepine library with vasopressin agonist activity.

A 23-member library of pyrrolobenzodiazepine derivatives with vasopressin agonist activity was purified on a 100-mg per injection scale using normal-phase (NP) automated mass-directed HPLC. Analytical NP APCI-LC/MS on an experimental monolith silica CN column utilizing gradients of methanol in ethoxynonafluorobutane (hexane-like solvent) was used to provide data on chromatographic purity and ionization of the solutes. The analytical data collected were used to program a preparative LC/MS instrument for "smart" fraction collection based on the protonated molecular ion of the component of interest. Preparative HPLC was carried out on a preparative cyano column with gradients of polar organic solvents in heptane containing n-propylamine as a basic additive. Flow rates twice as high as conventional ones were used for purification of library compounds. Small aliquots of the preparative flow were mixed with makeup solvent and introduced into an APCI source of a quadrupole mass spectrometer, which triggered collection of solutes. Two methods with fixed instrument parameters were used for purification. The system utilized commercially available instrumentation and software, which provided excellent recovery and purity of the library components and appeared to be useful as a fast and efficient alternative to traditional purification technologies based on reversed-phase LC/MS.

Discovery of begacestat, a Notch-1-sparing gamma-secretase inhibitor for the treatment of Alzheimer's disease.

SAR on HTS hits 1 and 2 led to the potent, Notch-1-sparing GSI 9, which lowered brain Abeta in Tg2576 mice at 100 mg/kg po. Converting the metabolically labile methyl groups in 9 to trifluoromethyl groups afforded the more stable analogue 10, which had improved in vivo potency. Further side chain modification afforded the potent Notch-1-sparing GSI begacestat (5), which was selected for development for the treatment of Alzheimer's disease.

Advances toward new antidepressants with dual serotonin transporter and 5-HT1A receptor affinity within a class of 3-aminochroman derivatives. Part 2.

Novel compounds combining a 5-HT 1A moiety (3-aminochroman scaffold) and a 5-HT transporter (indole analogues) linked through a common basic nitrogen via an alkyl chain attached at the 1- or 3-position of the indole were evaluated for dual affinity at both the 5-HT reuptake site and the 5-HT 1A receptor. Compounds of most interest were found to have a 5-carbamoyl-8-fluoro-3-amino-3,4-dihydro-2 H-1-benzopyran linked to a 3-alkylindole (straight chain), more specifically substituted with a 5-fluoro (( R)-(-)- 35c), 5-cyano ((-)- 52a), or 5,7-difluoro ((-)- 52g). Several factors contributed to 5-HT 1A affinity, serotonin rat transporter affinity, and functional antagonism in vitro. Although most of our analogues showed good to excellent affinities at both targets, specific features such as cyclobutyl substitution on the basic nitrogen and stereochemistry at the 3-position of the chroman moiety seemed necessary for antagonism at the 5-HT 1A receptor. Branched linkers seemed to impart antagonism even as racemates; however, the potency of these analogues in the functional assay was not desirable enough to further pursue these compounds.

Novel pyridyl-fused 3-amino chroman derivatives with dual action at serotonin transporter and 5-HT1A receptor.

Structural modifications of the initial lead, 3-aminochroman (4), led to the identification of a novel series of pyridyl-fused amino chroman derivatives (5-8) and the structural isomers (9-12). The compounds described were evaluated for dual 5-HT transporter inhibitory and 5-HT(1A) receptor activities. The design strategy, synthesis, and in vitro biological characterization for these novel compounds are described.

Enantiomeric separation and determination of absolute stereochemistry of asymmetric molecules in drug discovery: building chiral technology toolboxes.

The application of Chiral Technology, or the (extensive) use of techniques or tools for the determination of absolute stereochemistry and the enantiomeric or chiral separation of racemic small molecule potential lead compounds, has been critical to successfully discovering and developing chiral drugs in the pharmaceutical industry. This has been due to the rapid increase over the past 10-15 years in potential drug candidates containing one or more asymmetric centers. Based on the experiences of one pharmaceutical company, a summary of the establishment of a Chiral Technology toolbox, including the implementation of known tools as well as the design, development, and implementation of new Chiral Technology tools, is provided.

Relative hydrophobicity and lipophilicity of drugs measured by aqueous two-phase partitioning, octanol-buffer partitioning and HPLC. A simple model for predicting blood-brain distribution.

Relative hydrophobicity and lipophilicity of 63 compounds with known permeability through the blood-brain barrier (BBB) was examined by partitioning in aqueous dextran-poly(ethylene glycol) two-phase system and octanol-buffer system, and by gradient RP-HPLC at pH 7.4. Combination of the relative hydrophobicity estimates, N(CH(2)) obtained by aqueous two-phase partitioning and the lipophilicity (logD(exp) or logD(HPLC)) values obtained by the shake-flask technique or HPLC technique allows one to differentiate between compounds capable of crossing the BBB and those that cannot. A simple model for predicting blood-brain distribution is proposed.

Relative hydrophobicity and lipophilicity of beta-blockers and related compounds as measured by aqueous two-phase partitioning, octanol-buffer partitioning, and HPLC.

Partitioning of 15 beta-blockers and structurally related compounds was examined in aqueous dextran-PEG two-phase systems and octanol-buffer systems at pH from 2.0 up to 12.5. The same compounds were examined by gradient RP-HPLC at pH 2.0, 7.4, and 11.0. The differences between the hydrophobic character of the phases in all three systems at different pH values were characterized using a homologous series of dinitrophenyl-amino acids by measuring the free energy of transfer of a methylene group. Estimates of the relative hydrophobicity, N(CH(2)), and lipophilicity, logD, of the compounds obtained by the three techniques employed were compared. The data indicate that while similar pH profiles for a given compound were established by all these techniques, the information provided is different. It is suggested that the combination of the two descriptors, logD and N(CH(2)), may be useful for quantitative structure-activity relationship analysis of the biological activities involving distribution and/or transport of chemical compounds in biological systems.

Novel human metabolites of the angiotensin-II antagonist tasosartan and their pharmacological effects.

Three novel metabolites of the angiotensin-II (A-II) receptor antagonist tasosartan have been identified in humans, and the syntheses and pharmacologic profiling of these metabolites are reported. Each metabolite bound the human A-II receptor with IC(50)s between 20 and 45nM. The in vivo effects of these compounds in attenuating the pressor response to angiotensin-II challenge in anesthetized rats were also investigated. An unsaturated diol metabolite exhibited in vivo efficacy at intravenous doses of 1 and 3mg/kg, while the other metabolites, both carboxylic acids, had no significant effect at the same doses.