Letters in Drug Design & Discovery - Volume 3, Issue 1, 2006

A hypothetical receptor surface model has been generated for an allosteric receptor site, "lactone site", on the GABAA receptor using a set of N-substituted 4-amino-3, 3-dialkyl-2 (3H)-furanone GABAA receptor modulators (I). The activity data of each of the molecules was used as a weight in building of receptor surface. The study produced reasonably good predictive model with good conventional and cross-validated r2 with leave-two-out method (0.998 and 0.943 respectively) in the training set and also in external data set validation (r2pred =0.960). Most of the points selected for QSAR to conduct RSA are in the vicinity of the groups in position 3 and 4 and not in the vicinity of carbonyl group and oxygen atom region, predicted as favourable site for binding of molecules. These findings and the lack of direct correlation between interaction energy and biological activity led to infer that the compounds may function following "Message-Address" concept.

Physalins D (1), B (2), F (3), 5α-ethoxy-6β-hydroxy-5,6-dihydrophysalin B (4) and E (5), all isolated from Physalis angulata L. extracts, were tested for cytotoxic activity using a panel of tumor cell lines and sea urchin eggs. In general, the most active compounds were 1 and 3, followed by 2 and 4. Compound 4a obtained by the hydrogenation of 4 was weaker than all the others in tumor cells and possessed no activity in sea urchin eggs. Compound 5 had no activity in tumor cells and exhibited activity in sea urchin eggs only in the third cleavage and blastulae. The present data suggest that the cytotoxic effect of physalins is probably determined by the combination of the conjugated cyclohexanone moiety and the presence of an oxygen located at both C- 5 and C-6.

A facile synthesis of the disubstituted 1H-indole-2-carboxamides (6a-h) is described. Readily available 4-benzyloxy-3-methoxybenzaldehyde is converted to the parent acid (12) by nucleophilic attack of the azido-ester (9) and cyclization of the propenoic methyl ester (10). The target compounds (6a-d) were obtained by amidation of (12) with the appropriate primary amine. The new 6-hydroxy analogs (6e-h) were prepared by benzyl deprotection of (6a-d). The cytotoxicity of the new molecules was evaluated in the human non-small lung cancer cell line NSCLC-N16-L16 in vitro. One compound (6d) showed satisfactory activity (IC50 = 13.9 μM) worthy of further study. It is noteworthy that few agents are clinically effective against human non-small lung cancer, and thus there is a need for novel agents for use in this disease.

The high frequency of treatment failures suggests the need for more specific, less toxic and more active antiviral therapies for the Hepatitis C virus (HCV). HCV NS3 is currently regarded as a prime target for anti-viral drugs, thus, molecular modeling studies were used to try to understand the interaction of BILN 2061 macrocyclic analogs with the wild-type and the D168A mutant NS3 serine protease, with the aim of rendering them better therapeutic agents of the Hepatitis C virus infection.

Enantiomerically pure (2R,3S)-disubstituted tetrahydropyrans with diverse functional groups were synthesized. These derivatives were used as a model to study the influence of the tert-butyl dimethyl silyl group in the anticancer activity. The in vitro cytotoxicity was evaluated against a panel of six human cancer cells from diverse origin (MCF7, T-47D, HeLa, SW1573, WiDr and A2780). The structure-activity relationship study shows the relevant role of the silyl protecting group in the enhancement of the observed cytotoxic activity.

Tandem cyclizations to [2,5'] bis-1,3-azoles provided simplified and stable models of biological active marine natural products. The cytotoxic activity in HCT-15 cells and the effect on the L4 larvae of Nippostrongylus brasiliensis of the heterocycles were evaluated and provided data that serve for the preparation of bioselective new therapeutic agents.

The initial design and synthesis of conformationally restricted and pharmacophore-based scaffold hopping analogs of a Ras/Raf protein interaction inhibitor were undertaken with the objective of identifying alternate chemical scaffolds exhibiting similar biological activities. Evaluation of the MAPK pathway signaling inhibitory activity and antiproliferative activity of the synthesized derivatives were performed.

The 5-HT7 receptor is linked with various CNS disorders. Using an automated solution phase synthesis a combinatorial library of 384 N-substituted N-[1-methyl-3-(4-methylpiperidin-1-yl)propyl]- arylsulfonamides was prepared with 24 chemically diverse amines 1-24 and 16 sulfonyl chlorides A-P. The chemical library of alkylated sulfonamides was evaluated in a receptor binding assay with [3]H-5-CT as ligand. The key synthetic step was the alkylation of a sulfonamide with iodide E, which was prepared from butanediol in 4 synthetic steps. The target compounds 1A, 1B.....24A ... 24P were purified by solvent extraction on a Teacan liquid handling system. Sulfonamide J20, B23, D23, G23, G23, J23 , I24 and O24 displayed a binding affinity IC50 between 100 nM and 10 nM. The crystalline J20 (IC50=39 nM) and O24 (IC50=83 nM) were evaluated further in the despair swimming test and the tail suspension assay. A significant antidepressant activity was found in mice of a greater magnitude than imipramine and fluoxetine at low doses.

This paper reports the synthesis of 2,3,4,8,13a-hexahydro-1H-benzo[5,6]cyclohepta[1,2,3- ef][3]benzazepine derivatives (2a-d) as an extension of our studies about rigid congeners of 1- benzyltetrahydroisoquinoline. The new compounds were evaluated for affinities at D1 and D2 dopamine receptors. Compounds 2b-d showed similar D1 and D2 affinities to dopamine. 2,3,4,8,13a-hexahydro-1Hbenzo[ 5,6]cyclohepta-6,7-dihydroxy-[1,2,3-ef][3]benzazepine 2b and the N-methyl analogue 2d showed weak D1-like agonistic activity. This was demonstrated by their effect on the cyclic guanosine monophosphate (cGMP) content in rat neostriatal membranes.

Synthesis, biological evaluation and structure-activity relationships for a series of 8-sulfamoyl-1,3- dioxo-4-methyl-2,3-dihydro-1H-pyrrolo[3,4-c]quinolines are described. These compounds represent a new chemotype of nonpeptide small molecule inhibitors of caspase-3. Among the studied compounds, several potent inhibitors have been identified. The most active compounds within this series inhibited caspase-3 with IC50 in the range of 23-30 nM.