We report the efficient synthesis involving palladium-catalyzed reactions and biological evaluation of new naphthocarbazoles designed as potential anticancer agents. The use of 5- and 6-benzyloxyindoles generated three substitution sites which were successively exploited to introduce several hydrophilic side chains. The cytotoxicity of the newly designed compounds was evaluated on three cell lines. Several compounds showed a marked cytotoxicity with IC(50) values in the sub-micromolar range. This is the case for the 3-hydroxy-naphthopyrrolocarbazoledione 37, bearing a dimethylaminoethyl side chain, which is extremely cytotoxic to L1210 and DU145 cells (IC(50): 36 nM, 108 nM) and induces an accumulation of L1210 cells in the G2+M phases of the cell cycle. Some of the most cytotoxic compounds were tested for inhibition of CDK-5, GSK-3 and topoisomerase I, and their interaction with DNA was also evaluated. Interaction with DNA was detected, suggesting that nucleic acids represent a privileged target for these molecules.

The work described herein aims at finding new potential ligands for the brain imaging of 5-HT4 receptors using single-photon emission computed tomography (SPECT). Starting from the non-substituted phenanthridine compound 4a exhibiting a Ki value of 51 nM on 5-HT4R, we explored structure-affinity in this series. We found that substitution in position 4 of the tricycle with a fluorine atom gave the best result. Introduction of an additional nitrogen atom inside the tricyclic framework led to increase both the affinity and the selectivity for 5-HT4R suggesting the design of the antagonist 4v exhibiting a high affinity of 0.04 nM. Several iodinated analogues were then synthesized as potential SPECT tracers. The iodinated compound 11d was able to displace the reference radioiodinated 5-HT4R antagonist (1-butylpiperidin-4-yl)methyl-8-amino-7-iodo[123I]-2,3-dihydrobenzo[b][1,4]dioxine-5-carboxylate ([123I]1, [123I]SB 207710) both in vitro and in vivo in brain. Compound 11d was radiolabeled with [125I]iodine, providing a potential SPECT candidate for brain imaging of 5-HT4R.

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A series of 1-substituted 3,4-dihydroisoquinolines were synthesized and tested in vitro against the leukemia L 1210 cell line to evaluate their ability to perturb the cell cycle by arresting cells in the G1 phase. 1-Benzoylimines, 1-phenylimines, and 1-alkylimines were synthesized. The most powerful cytotoxic derivatives, 1-benzoyl-3,4-dihydroisoquinolines (1-26), were obtained from amides I via 1-benzyl-3,4-dihydroisoquinoline in good yield by a direct selective oxidation of the benzylic carbon of the corresponding imines through 10% Pd/C in acetonitrile. SAR studies let us to identify the essential structural features for cytotoxic activity. The most bioactive compounds (with IC(50) < 5 microM) were BzDHIQ (13, 22, 21, 8, 9, 11, 1, 20, 6, and 19), and they are characterized by the following: (i) An alpha-ketoimine moiety is necessary for potent antiproliferative activity (1-phenyl- and 1-alkyl-3,4-dihydroisoquinoline derivatives, 34-40, are less active). (ii) An hydrophobic, benzyloxy, alkyloxy, or allyloxy group at the C-6 position seems to be relevant for cytotoxicity. (iii) Regarding the influence of the benzoylic moiety, both the unsubstituted (13, 8, 9, 11, 1, and 6) and the 3'-monosubstituted (22, 21, 20, and 19) compounds were more potent than compounds with other substitutions.

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A set of disubstituted tetracyclic lactones has been synthesized and tested for potential antitumor activity. Several of them possess a noticeable cytotoxicity against L1210 and HT-29 colon cells in vitro. Relationships between chain nature and biological properties were sought. Lactones with a pentyl or hexyl substituent at C-11 are the most active ones. The introduction of a functional group at the side chain of C-11 modified the potency; carboxylic acid and primary amine decreased the cytotoxicity, whereas a cyano group increased the activity. An extensive structure-activity relationship study of these derivatives, including carbon homologues and bioisosteres has been performed. The synthesis and cytotoxicity of these compounds are discussed. Two lactones are recognized as potential lead compounds.

AIM: These studies were performed to test the hypothesis that endogenous neuropeptide Y (NPY) acting on the NPY Y 5 receptor subtype contributes to the control of food intake. The hypothesis was tested using S 25585Fa newly synthesized NPY Y 5 receptor antagonist. METHODS AND RESULTS: S 25585 was shown to be a high-affinity antagonist of the NPY Y 5 receptor subtype (IC 50 5 nM) with no significant affinity toward other NPY receptor subtypes and over 40 other receptors, channels or uptake systems. S 25585 (7.5 mg/kg, i.p.) did not induce a conditioned taste aversion, significantly alter need-induced sodium appetite or induce pica, suggesting that at this dose the compound did not induce illness or malaise. In satiated rats, S 25585 (5.0 and 7.5 mg/kg, i.p.) significantly decreased the overfeeding induced by i.c.v. injection of NPY (1 mg) and the highly selective NPY Y 5 receptor agonist [hPP 1À17 , Ala 31 , Aib 32 ]NPY (0.7 mg). In rats fasted for 4 h immediately before the dark phase, analysis of the microstructure of feeding behavior revealed that S 25585 significantly increased latency to eat and significantly decreased the duration and size of the meals without altering the meal number or eating rate. Analysis of the behavioral satiety sequence at this time revealed that the animals passed through the normal pattern of feeding, grooming and resting. Although S 25585 appeared to be influencing a physiological system controlling appetite, this does not involve the NPY Y 5 receptor since the antagonist also markedly reduced food intake in the NPY Y 5 knockout mouse. CONCLUSIONS:The results presented do not support a role for the NPY Y 5 receptor in the control of food intake. The results further illustrate that it is imperative that the activity of any new NPY Y 5 antagonist be assessed in the NPY Y 5 knockout mouse before assuming that its effect on food intake is due to blockade of this receptor.