4-Azatricyclo[5.2.2.02,6]undecane-3,5,8-triones as Potential Pharmacological Agents

A series of twenty six arylpiperazine and aminoalkanol derivatives of 4-aza-tricyclo[5.2.2.02,6]undecane-3,5,8-trione have been prepared. The synthesized compounds were evaluated for their cytotoxicity and anti-HIV-1 activity in MT-4 cells.

The molecular geometry adopted in the solid-state by 1, 2 and 5e is influenced by a pattern of intermolecular contacts. The imide part of 1 and 2 is involved in intermolecular N-H...O hydrogen bonds which differentiate two peptide units: N1-C2=O2 and N1-C1=O1, causing the lengthening of the C=O bond and the shortening of C-N distance around the O atom being an acceptor of hydrogen bond . The dimeric association around the center of symmetry is observed in the crystal structure of 1, while molecules 2 form chains. In contrast, the imide moiety of 5e is symmetric having equal respective bond lengths within the (O1)C1-N1-C2(O2) fragment. The hydrocarbon skeleton is rigid.
Thirty one new compounds were obtained. The synthesized compounds were evaluated for their cytotoxicity and anti-HIV-1 activity in MT-4 cells. The results are shown in Table 1. None of investigated compounds showed any anti HIV-1 activity, however, their cytotoxicity determined by the MTT method is greater then 100 μM.

General
All chemicals and solvents were purchased from Aldrich (Vienna, Austria). Melting points were determined on Electrothermal Digital Melting Point Apparatus (Essex, UK) and are uncorrected. The 1 H-NMR spectra were recorded on a Bruker (Rheinstetten, Germany) spectrometer, operating at 400 MHz. The chemical shift values are expressed in ppm relative to TMS as an internal standard. Elemental analyses were recorded on a CHN model 2400 Perkin-Elmer (Hitachi, Tokyo, Japan). TLC was carried out using silica gel 60 F 254 , layer thickness 0.25 mm (E. Merck, Darmstadt, Germany) and the results were visualized using UV lamp at 254 nm. Column chromatography was carried out using silica gel 60 (200-400 mesh, Merck). The X-ray diffraction data were collected at 295 K with a KM4 diffractometer using graphite monochromated CuKα radiation (λ = 1.54178 Å) and ω/2θ scan mode. Structures were solved by the SHELXS-97 program [20] and refined by full-matrix least-squares on F 2 using the SHELXL-97 program [21]. Non hydrogen atoms were refined with anisotropic displacement parameters. Carbon-bonded H-atoms were posititoned geometrically and 'riding' model was used in the refinement. The H-atoms of the hydroxyl, imide and piperidine groups were located on difference maps. The experimental details and final atomic parameters for 1, 2 and 5e have been deposited with the Cambridge Crystallographic Data Centre as supplementary material under deposition numbers CCDC 659529-659531, respectively. Copies of the data can be obtained free of charge on application to The Director, CCDC, 12 Union Road, Cambridge CB2 1EZ, UK, Fax: +44-1223-336-033; e-mail: deposit@ccdc.cam.ac.uk or www: http://www.ccdc.cam.ac.uk.

Biological Assays: Compounds
Compounds were dissolved in DMSO at 100 mM and then diluted in the culture medium.

Cells and Viruses
Cell lines were purchased from American Type Culture Collection (ATCC). The absence of mycoplasma contamination was checked periodically by the Hoechst staining method. Cell lines supporting the multiplication of RNA viruses were the following: CD4 + human T-cells containing an integrated HTLV-1 genome (MT-4).

Antiviral assay
Activity of compounds against Human Immunodeficiency virus type-1 (HIV-1) was based on inhibition of virus-induced cytopathogenicity in MT-4 cells acutely infected with a multiplicity of infection (m.o.i.) of 0.01. Briefly, 50 μL of RPMI containing 2×10 4 MT-4 were added to each well of flat-bottom microtitre trays containing 50 μL of RPMI, without or with serial dilutions of test compounds. Then, 20 μL of an HIV-1 suspension containing 100 CCID 50 were added. After a 4-day incubation, cell viability was determined by the MTT method.