Hemisynthesis and antiproliferative properties of mono-[O-(14-benzoylaconine-8-yl)]esters and bis-[O-(14-benzoylaconine-8-yl)]esters.

A series of mono- and bifunctional acyl compounds, build from the 8-O-azeloyl-14-benzoylaconine scaffold and differing by the length of the alkyl linker chain, were synthesised and evaluated against a panel of human tumour cell lines, A-549 (lung cancer), MCF-7 (breast cancer) and HCT-15 (colon cancer). None of the mono-[O-(14-benzoylaconine-8-yl)]esters displayed in vitro activity against tumour cells (IC(50) > 60 µM). However, three bis-[O-(14-benzoylaconine-8-yl)]esters presented a noticeable in vitro cytotoxic activity, those bearing 7, 8 and 9 carbon atoms between the two aconitine moieties, with IC(50)s ranging between 4 and 28 µM. The most active, bis[O-(14-benzoylaconine-8-yl)]suberate, was then evaluated in vivo in immunodeficient mice bearing human tumour xenografts originating from MCF-7 and HCT-15 cells. For MCF-7 cells, administration of five doses every 4 days, and weekly administration of 4 doses resulted in T/C percent values of 36% (p = 0.001) and 56% (p = 0.02) on day 45, respectively. For HCT-15 cells, administration of five doses every 3 days resulted in 49% tumour regression on the 25th day (p = 0.00001).

Relative helix-helix conformations in branched aromatic oligoamide foldamers.

The de novo design and synthesis of large and well-organized, tertiary-like, α-peptidic folded architectures is difficult because it relies on multiple cooperative interactions within and between secondary folded motifs of relatively weak intrinsic stability. The very stable helical structures of oligoamides of 8-amino-2-quinoline carboxylic acid offer a way to circumvent this difficulty thanks to their ability to fold into predictable and stable secondary motifs. Branched architectures comprised of two pairs of tetrameric (1), pentameric (2), or octameric (3) oligomers connected via an ethylene glycol spacer were designed and synthesized. The short spacer holds two helices in close proximity, thus enabling interactions between them. Degrees of freedom allowed in the system are well-defined: the relative P or M handedness of the two helices; the relative orientation of the helix axes; and the gauche or anti conformation of the ethylene spacer. Investigating the structures of 1-3 in the solid state and in solution allowed a detailed picture to be drawn of their conformational preferences and dynamics. The high variability of the solid state structures provides many snapshots of possible solution conformations. Helix-helix handedness communication was evidenced and shown to depend both on solvent and on a defined set of side chains at the helix-helix interface. Interdigitation of the side chains was found to restrict free rotation about the ethylene spacer. One solid state structure shows a high level of symmetry and provides a firm basis to further design specific side chain/side chain directional interactions.

Antiproliferative effect on HepaRG cell cultures of new calix[4]arenes. Part II.

Cell cycle progression is dependent on the intracellular iron level and chelators can lead to iron depletion and decrease cell proliferation. This antiproliferative effect can be inhibited by exogenous iron. In this work, we present the synthesis of some new synthetic calix[4]arene podands bearing diamino-tetraesters, diamino-tetraalcohols, diamino-tetraacid and tetraaryloxypentoxy groups at the lower rim, designed as potential iron chelators. We report their effect on cell proliferation, in comparison with the new oral chelator ICL670A (4-[3,5-bis-(2-hydroxyphenyl)-1,2,4-triazol-1-yl]-benzoic acid). The antiproliferative effect of these new compounds was studied in the human hepatocarcinoma HepaRG cell cultures using cell nuclei counting after staining with the DNA intercalating fluorescence dye, Hoechst 33342. Their cytotoxicity was evaluated by the extracellular LDH activity. Preliminary results indicated that their antiproliferative effect was mainly due to their cytotoxicity. The efficiency of these compounds, being comparable to that of ICL670, was independent of iron depletion. This effect remains to be further explored. Moreover, it also shows that the new substituted calix[4]arenes could open the way to valuable new approaches for medicinal chemistry scaffolding.

Antiproliferative effect on HepaRG cell cultures of new calix[4]arenes.

Cell cycle progression is dependent on the intracellular iron level, and chelators lead to iron depletion and decrease cell proliferation. This antiproliferative effect can be inhibited by exogenous iron. In this work, we present the synthesis of new synthetic calix[4]arene podands bearing alkyl acid and alkyl ester groups at the lower rim, designed as potential iron chelators. We report their effect on cell proliferation, in comparison with the new oral chelator ICL670 (4-[3,5-bis-(2-hydroxyphenyl)-1,2,4-triazol-1-yl]-benzoic acid). The antiproliferative effect of these new compounds was studied in human hepatocarcinoma HepaRG cell cultures using the MTT assay. Their cytotoxicity was evaluated by extracellular LDH activity. Preliminary results indicate that their antiproliferative effect is due to their cytotoxicity. The efficiency of these compounds, comparable to that of ICL670, was independent of iron depletion. This effect remains to be further explored. Moreover, it also shows that novel substituted calix[4]arenes could open the way to new valuable medicinal chemistry scaffolding.

Synthesis and in vitro cytostatic activity of new beta-D-arabino furan[1',2':4,5]oxazolo- and arabino-pyrimidinone derivatives.

A series of nucleoside derivatives was obtained via heteroatom annulation of the amino oxazoline of D-(-)-arabinose. Unequivocal proofs for the stereostructure of some new arabinosyl pyrimidinone derivatives were obtained by X-ray structure analysis. These newly synthesized compounds were then evaluated for their cytostatic activity against murine leukemia (L1210), and human T-lymphocytes (Molt 4/C8 and CEM). Of all the compounds in the series, the protected silylated tricyclic fused pyrimidinone 10 showed the most significant antitumor activity against murine leukemia L1210 (IC(50)=6 microM), and human T-lymphocytes cells Molt 4/C8 (IC(50)=7.9 microM) and CEM/0 cell lines (IC(50)=7.5 microM). None of the compounds exhibited significant antiviral inhibitory activities.

Synthesis and preliminary evaluation of new 1- and 3-[1-(2-hydroxy-3-phenoxypropyl)]xanthines from 2-amino-2-oxazolines as potential A1 and A2A adenosine receptor antagonists.

The development of potent and selective adenosine receptor ligands as potential drugs is an active area of research. Xanthines are one of the most important classes of adenosine receptor antagonists and have been widely developed in terms of affinity and selectivity for adenosine receptors. We recently developed new original pathways for the synthesis of xanthine analogues starting from 5-substituted-2-amino-2-oxazoline 5 as a synthon. These procedures allowed us to selectively introduce a large, functionalized and beta-adrenergic 2-hydroxy-3-phenoxypropyl pharmacophore at the 1- and 3-position of the xanthine moiety which allowed further structural modifications. In this study, we present a new synthetic access to racemic xanthine derivatives 1-4 from 5, and their evaluation as adenosine A1, A2A and A3 receptor ligands in radioligand binding studies. The 2-hydroxy-3-phenoxypropyl moiety was well tolerated in the 3-position of the xanthine core, while its introduction in the 1-position of the xanthine moiety led to a large decrease in adenosine receptor affinity. 1,7-Dimethyl-3-[1-(2-chloro-3-phenoxypropyl)]-8-(3,4,5-trimethoxystyryl)xanthine (2n) was the most potent and selective A2A antagonist of the present series (Ki=44 nM, >>200-fold selective vs A1). 1-Propyl-3-[1-(2-hydroxy-3-phenoxypropyl)]-8-noradamantylxanthine (3f) was identified as a potent (KiA1=21 nM) and highly selective (>>350-fold vs A2A and A3 receptor) adenosine A1 receptor antagonist.

Aromatic delta-peptides.

Oligoamides of 8-amino-2-carboxy-quinoline adopt a very stable helical conformation characterized in solution by 1H NMR and in the solid state by single-crystal X-ray diffraction. The helix comprises only 2.5 units per turn, which represents the highest curvature achieved by aromatic oligoamides until now. Monomers possessing alkoxy substituents in position 4 are easily available from 2-nitroaniline and dimethyl acetylenedicarboxylate.

Synthesis of a novel class of non-peptide NK-2 receptor ligand, derived from 1-phenyl-3-pyrrol-1-ylindan-2-carboxamides.

A series of trans,trans-1-phenyl-3-pyrrol-1-ylindan-2-carboxamide derivatives has been synthesized in eight steps starting from cinnamic acid or 3,3-diphenylpropionic acid. The trans,trans configuration of these carboxamides has been established by X-ray analysis and by NOE experiments in NMR. These new compounds were evaluated for their potential NK-1, NK-2 and NK-3 receptors binding affinity. The N,N-disubstituted carboxamides bound selectively on NK-2 receptors.

Anti-leukemia activity of 7-hydroxy-2-substituted-methyl-5H-oxazolo[3,2-a]pyrimidin-5-one derivatives.

The synthesis of new 7-hydroxy-2-substituted-methyl-5H-oxazolo[3,2-a]pyrimidin-5-ones derivatives, designed as structural bicyclic analogues of the iron chelator deferiprone, is described. They were tested for their ability to inhibit proliferation in human Bcr-Abl+ leukemia cells.