Association of two 3D QSAR analyses. application to the study of partial agonist serotonin-3 ligands.

CATALYST and COMFA, two software packages for 3D QSAR studies, were associated to correlate the three-dimensional structures of 75 serotonin 5-HT3 ligands to their biological affinities. The conformational analysis and the influence of chemical function-based alignments (the basis of this association) on final results are discussed in this publication. These two analyses allow for precisely quantitating the weights of significant chemical groups or functions on the biological affinities.

First tricyclic oximino derivatives as 5-HT3 ligands.

The design and synthesis of a new type of 5-HT3 ligand with subnanomolar affinity are described. The O-dialkylaminoethyloximinothienopyrrolizine structure was deduced from molecular modeling studies by replacement of an amidine moiety by an oximino one.

Biological properties of 5,11-dimethyl-6H-pyrido[3,2-b]carbazoles: a new class of potent antitumour drugs.

Thirteen 5,11-dimethyl-6H-pyrido[3,2-b]carbazoles, structurally related to the antitumour drug ellipticine, were tested for their cytotoxicity against the L1210 murine leukaemia cell line and their antitumour activity against both leukaemias and solid tumours. Most of them showed an interesting antitumour activity against L1210 leukaemia, 4-hydroxy-9-chloro-2,3, 5,11-tetramethyl-6H-pyrido[3,2-b]carbazole displaying a high antitumour activity against L1210 and P388 leukaemias, B16 melanoma and M5076 sarcoma. Despite promising cytotoxic activity, 4-ethoxy-5,11-dimethyl-6H-pyrido-[3,2-b]carbazole had no antitumour activity. The ability of four drugs to induce strand breaks in DNA was studied using the single cell gel electrophoresis assay (comet assay). Most of the molecules induced DNA breaks that were totally or partially repaired after 1 h. The effects of these compounds on the L1210 cell cycle were tested as well as their abilities to induce apoptosis in these cells. Three of them induced a G2/M blockade, without any obvious evidence of apoptosis. The other compound, 4-ethoxy-5,11-dimethyl-6H-pyrido[3,2b]carbazole, did not lead to phase-specific blockade, but was a strong inductor of apoptosis in L1210 cells.

Evaluation of analgesic and anti-inflammatory activity of novel beta-lactam monocyclic compounds.

We have examined the in vivo anti-inflammatory and analgesic activity of a new series of monocyclic beta-lactams (azetidinones), similar to others which have been demonstrated to be inhibitors of human leukocyte elastase (HLE), an enzyme involved in degradation processes of connective tissue. Our new compounds have been administered orally (15 mg/kg) to albino rats 30 min before injecting carrageenin in the plantar aponeurosis. Tested compounds have demonstrated a certain activity and stability to gastric hydrolysis, in particular two of them markedly reduced paw edema formation, even if slightly less effectively than indomethacin (reference compound, 5 mg/kg). To evaluate the analgesic activity we carried out the acetic acid writhing test, pretreating rats orally with our compounds 30 min before injecting the acid solution i.p. The same two molecules which showed the anti-inflammatory activity demonstrated a very light analgesic activity. These results suggest the possibility of carrying out further studies, particularly in vitro, on the mechanism of action of our compounds, mechanism which could be the HLE inhibition.

Definition of a pharmacophore for partial agonists of serotonin 5-HT3 receptors.

A definition of a partial agonists serotonin 5-HT3 pharmacophore was carried out by considering a three-dimensional model which correlates the chemical structures of series of piperazinopyrrolothienopyrazines, piperazinopyridopyrrolopyrazines, piperazinopyrroloquinolaxines, piperazinopyridopyrroloquinoxalines, aminoalkyloximinopyrroloindoles, aminoalkyloximinothienopyrrolizines, and aminoalkyloximinopyrrolizines with the biological affinities. The model is formed by five features corresponding to two hydrogen bond acceptors, one aromatic ring, one hydrophobic group, and one positive ionizable site (quaternary ammonium ions). The nature of the features and the distances between them explain the partial agonist activities of these compounds.

Amide derivatives with H1-antihistaminic effect.

The synthesis and the structure-activity correlation of a series of N-aminoalkylacetamides as H1-antihistaminic agents have been carried out. The compounds were tested in vitro by measurement of the inhibition of histamine-induced contractions on isolated guinea pig ileum; the results are expressed as pA2.

A new class of pyrrolidin-2-ones: synthesis and pharmacological study. II.

The anticonvulsant activity of a second series of pyrrolidin-2-ones (1-2a, 1-4b, 1-9c) was tested on pentylenetetrazole (PTZ) treated mice. The compounds were obtained by acylation of N-(3'-aminopropyl)-2-pyrrolidinone with the suitable acid chloride.

In Vivo Nitric Oxide Synthase Inhibitors Can Be Deprived of This Activity: Unexpected Influence of the Tetrachloroplatinate(II) Counteranion. Crystal Structures of Bis(S-Methyl-Isothiouronium)-N,N'-Bis(3-Guanidinopropyl)Piperazinium and Hexamidinium Tetrachloroplatinates(II) Salts.

The synthesis and crystal structures of bis(S-methylisothiouronium) (MSTUH)(+), N,N'-bis((3- guanidinopropyl)piperazinium (PipeC3GuaH4)(4+) and hexamidinium (HexaH2)(2+) tetrachloro platinate(ll) salts ( called hereafter PtMSTU, PtPipeC3Gua and PtHexa respectively ) were investigated. These compounds contain the "amidine" function ( - C(=NH)NH(2) ) in which the H atoms supplied by the acid have become attached to the imino group of each terminal amidino function. Moreover, in PtPipeC3Gua, the nitrogen atoms of the chair-piperazine moiety are also protonated. The influence of tetrachloroplatinate(ll) counteranion ( versus sulfate, nitrate and diisethionate ) in the in vivo nitrite inhibition by the (MSTUH)(+), (PipeC3GuaH4)(4+) and (HexaH2)(2+) cations was investigated. The three tetrachloroplatinate(ll) salts, unexpectedly, do not inhibit significantly the in vivo nitrite production in comparison with the other salts (sulfate, nitrate and diisethionate and their corresponding previous countercations) which exhibit NO synthase inhibition, especially bis(S-methylisothiouronium) sulfate, a selective and potent inducible NO synthase (iNOS) inhibitor commonly used as standard.

Synthesis, Crystal Structure and Interaction With DNA of N,N'-(Butane-1,4-Diyl)Bis(Guanidinium) Tetrachloroplatinate (II).

The design, synthesis, crystal structure and interaction with DNA of the N,N'-(butane-1,4-diyl)bis(guanidinium) tetrachloroplatinate(ll) are described. Crystal data: a = 8.152(1), b = 8.889(4), c = 10.700(3) A , alpha = 81.59(3), beta = 87.99(5), gamma = 78.48(6) degrees , V = 752(1) A(3), Z = 2 , space group P-1. The structure was refined to R = 0.039 and Rw = 0.046 from 1853 reflections (I > 3sigma(I)). This compound, named PtC(4)Gua, does not exhibit a center of symmetry and the center linker chain C(2) - C(3) - C(4) - C(5) is in gauche conformation. The cation is bisprotonated with the H(+) attached to the imine group of each terminal guanidinium function. The presence of the platinum moiety reinforces the binding of the butane(bis)guanidinium structure with double stranded DNA as judged from thermal denaturation studies and DNA unwinding experiments.

In vivo inhibition of nitric oxide synthase by bisisothiouronium and bisguanidinium salts.

The ability of two S,S'-(alkane-1,omega-diyl) bisisothiouronium dibromides, three N,N'-(alkane-1, omega-diyl) bis guanidinium dinitrates and N,N'-bis (3-guanidinopropyl)piperazine dinitrate to inhibit constitutive (i.e. endothelial and neuronal forms) and inducible forms of nitric oxide synthases has been evaluated in vivo. These compounds, synthesized by two of us (J. C. L. and C. S.), have been tested in vivo; they were administered simultaneously with an irritant (carrageenan lambda) into the pleural cavity. The amount of nitrites collected 0.5 and 7 hours after this injection can be considered as an indicator of nitric oxide (NO) production. According to previous data, the first harvesting time can be related to activation of constitutive NO synthases and the second to activation of inducible NO synthases. These substances significantly inhibited nitrite production as did 2-methyl-2-thiopseudourea sulphate, previously described as a potent inhibitor of NO synthases and considered as the reference compound. The inhibiting effect varied according to the chemical structure of the compounds. Results were significantly different from controls at 0.5 h only with the S,S'-(octane-1,8-diyl) bisisothiouronium dibromide and the S,S'-(nonane-1,9-diyl) bisisothiouronium dibromide at the highest concentration, N,N'-(heptane-1,7-diyl) bisguanidinium dinitrate and N,N'-bis (3-guanidinopropyl)piperazine dinitrate. At 7 h, all the results were significantly different from controls, with a major effect observed with N,N'-(heptane-1,7-diyl) bisguanidinium dinitrate. The most active substances exerted similar effects to the reference substance.

Novel and selective partial agonists of 5-HT3 receptors. 2. Synthesis and biological evaluation of piperazinopyridopyrrolopyrazines, piperazinopyrroloquinoxalines, and piperazinopyridopyrroloquinoxalines.

In continuation of our previous work on piperazinopyrrolothienopyrazine derivatives, three series of piperazinopyridopyrrolopyrazines, piperazinopyrroloquinoxalines, and piperazinopyridopyrroloquinoxalines were prepared and evaluated as 5-HT3 receptor ligands. The chemical modifications performed within these new series led to structure-activity relationships regarding both high affinity and selectivity for the 5-HT3 receptors that are in agreement with those established previously for the pyrrolothienopyrazine series. The best compound (8a) obtained in these new series is in the picomolar range of affinity for 5-HT3 receptors with a selectivity higher than 10(6). Four of the high-affinity 5-HT3 ligands (8a, 15a,b, and 16d) were selected in both the pyridopyrrolopyrazine and the pyrroloquinoxaline series and were characterized in vitro and in vivo as agonists or partial agonists. Compound 8a was also evaluated in the light/dark test where it showed potential anxiolytic-like activity at very low doses per os.

Sequence-selective binding to DNA of bis(amidinophenoxy)alkanes related to propamidine and pentamidine.

The DNA sequences targeted by a complete homologous series of aromatic diamidines have been determined at single-nucleotide resolution via protection from cutting by the endonucleases DNase I, DNase II and micrococcal nuclease. Propamidine, pentamidine and to a lesser extent hexamidine bind selectively to nucleotide sequences composed of at least four consecutive A-T base pairs. In contrast, the binding to DNA of butamidine, heptamidine, octamidine and nonamidine is poorly sequence-selective. Sequences composed of only three consecutive A-T base pairs do not afford a potential binding site for propamidine or the longer homologues, and none of the drugs tolerate the presence of a G-C base pair within the binding site. Experiments with DNA molecules containing inosine in place of guanosine and 2,6-diaminopurine in place of adenine reveal that the lack of binding of propamidine to GC-containing sites is attributable to an obstructive effect of the exocyclic 2-amino group of guanosine. The present data support the view that the local conformation of the double helix (in particular the width of the minor groove) plays a dominant role in the binding reaction and that the capacity of diamidines to recognize AT-rich sequences selectively varies considerably depending on the length of the alkyl chain. The evidence indicates that binding to AT-tracts in DNA must play a role in the biological activity of these diamidines, but there is no simple correlation between binding and pharmacological efficacy.

Synthesis and pharmacological activities of some 2,3,4,5-tetrahydro[1,5]benzo[f]thiazepines.

In search of new biological active agents in the series of [1,5]benzothiazepines, some 2,3,4,5-tetrahydro-N-(5-morpholinopentanoyl)-[1,5]benzo[f] thiazepines were synthesized and examined in vitro for their calcium antagonist activity compared to the Diltiazem one.

Mutagenicity of nitro- and amino-substituted carbazoles in Salmonella typhimurium. III. Methylated derivatives of 9H-carbazole.

The mutagenic potency of nine methylnitrocarbazoles, four methylaminocarbazoles and the methylcarbazole parent compounds was evaluated in Salmonella typhimurium TA98 and TA100, in the absence and presence of S9 isolated from Aroclor-induced rat liver. Nitro derivatives were additionally tested in TA98NR and TA98/1,8DNP6, and mutagenicity of nitrocarbazoles bearing methyl groups in positions 1 and 4 was also determined in TA1537 and TA1977, with and without S9. The addition of methyl groups on non-mutagenic carbazole can induce a mutagenic response where the intensity and nature of the effect depends on the position of the substitution: base-pair substitutions were only observed for N-methylated carbazoles, whereas 1,4-dimethylated compounds exhibited frameshift mutagenicity. All these activities depended on the presence of S9. From its dependence on classical nitroreductases, direct mutagenicity of methylnitro derivatives should be attributed to bacterial reduction of nitro groups. The influence of the methyl groups (and other additional substituents) on mutagenicity of these derivatives is discussed through their effects on life-time and reactivity of the intermediates (i.e., hydroxylamines and nitrenium ions), taking into account the nature, the position and the number of substituted sites Mutagenic activity of methylnitrocarbazoles was also tentatively correlated with various molecular descriptors. Among them hydrophobicity was found to be strongly correlated with the mutagenicity of the 1,4diMe3NC isomers. On the other hand, mutagenic potency of the nitrated and aminated methylcarbazoles varied independently of parameters linked to their oxidoreduction properties (i.e., reduction and oxidation potentials, LUMO and HOMO energies).

In vitro effects of Celiptium and MR 14504 on mature rat Leydig cell testosterone production.

Percoll-purified mature rat Leydig cells have been used to evaluate the testicular toxicity of two highly potent intercalating agents (Celiptium and MR 14505). Testosterone secretion in the absence and in the presence of human chorionic gonadotropin (hCG) was measured to assess Leydig cell function. Celiptium and MR 14504 induce time- and dose-related inhibitory effects on the production of testosterone by Leydig cells, both in the presence and in the absence of hCG, whatever the concentration of hCG used. We have observed that MR 14504 is about 5 times more potent as an inhibitor of rat Leydig cell steroidogenesis than Celiptium without inducing any cell toxicity. The present study indicates that the Leydig cell is an additional potential site for the primary toxic effects of these drugs in the adult rat testis.

Novel selective and partial agonists of 5-HT3 receptors. Part 1. Synthesis and biological evaluation of piperazinopyrrolothienopyrazines.

A series of piperazinopyrrolo[1,2-a]thieno[3,2-e]- and -[2,3-e]pyrazine derivatives were prepared and evaluated in order to determine the necessary requirements for high affinity on the 5-HT3 receptors and high selectivity versus other 5-HT receptor subtypes. Various substitutions on the piperazine and the thiophene ring of the pyrrolothienopyrazine moieties were systematically explored as well as replacement of the piperazine by other cyclic amines. The best compounds are in the nanomolar range of affinity of 5-HT3 receptors with high to very high selectivity (up to 10,000 for 14b). These high-affinity compounds have in common a benzyl- or allylpiperazine substituent with no substitutions on the thiophene ring. Five of these compounds (1a, 4b, 13a,b, and 14b) have been evaluated on the Von Bezold-Jarisch reflex and were characterized as partial agonists. One of them, 13a, has shown in vivo at very low dose a potent anxiolytic-like activity in the light/dark test.

Amoebicidal efficiencies of various diamidines against two strains of Acanthamoeba polyphaga.

The first medical cure of Acanthamoeba keratitis was obtained by use of propamidine isethionate. Since then, it has been the basic drug recommended for use in treatment. Because some Acanthamoeba strains have been reported to be resistant to propamidine and propamidine was found to be only weakly cysticidal, superior homologs such as butamidine, pentamidine, hexamidine, heptamidine, octamidine, and nonamidine were tested for their amoebicidal effects on two Acanthamoeba strains isolated from patients with keratitis. Trophozoicidal and cysticidal efficiencies were found to be increased from propamidine to nonamidine; i.e., when the alkyl chain connecting the two benzene rings in their molecular structures was elongated, in comparison with propamidine, hexamidine and octamidine were the most amoebicidal molecules. As a result of these data, a kinetic study carried out on propamidine, hexamidine, and octamidine demonstrated that the amoebicidal effects resulted from two events: the diffusion of molecules through the plasma membrane or the double wall of trophozoites or cysts, respectively, and the lethal effects of molecules on amoebic protoplasm. The diffusion kinetics were increased when the alkyl chain was elongated, i.e., with an increase in the lipophilic properties of molecules. In contrast, the lethal effect kinetics were found to be unchanged by this elongation, indicating that they originated from the cationic surface-active properties induced by the protonated amidine groups attached to each benzene ring, which themselves remained unchanged from one molecule to the other. These results strongly advocate the immediate replacement of propamidine by hexamidine in the medical treatment of Acanthamoeba keratitis; in France, 0.1% hexamidine eyedrops are available (Desomedine). The results also advocate clinical investigations on the efficiency and toxicity of octamidine, which appears to be the most amoebicidal diamidine in vitro.

Mutagenicity of nitro- and amino-substituted carbazoles in Salmonella typhimurium. I. Monosubstituted derivatives of 9H-carbazole.

Mononitro, monoamino and monoacetamido carbazoles were assayed for mutagenicity in Salmonella typhimurium strains TA1535, TA1538, TA1537, TA1977, TA98 and TA100, with and without the addition of S9 from phenobarbital-induced rat liver. The role of bacterial metabolism of the nitro group was also studied using the additional strains TA98NR and TA98/1,8DNP6. None of the compounds was active in TA1535, while only 2-nitrocarbazole and 3-nitrocarbazole presented a weak mutagenicity towards its pKM101 derivative, TA100. All four nitrocarbazole isomers were mutagenic for TA1538 and TA98, their activities decreasing in the order: 2-nitrocarbazole approximately 3-nitrocarbazole > 1-nitrocarbazole > 4-nitrocarbazole. Direct-acting mutagenicities for TA1537 were lower than for TA1538, but varied in the same order. Nitro reduction was an important step of metabolic activation of nitrocarbazoles, as indicated by the dramatic reduction of activity with TA98NR, as compared to TA98. Results obtained with TA98/1,8DNP6 showed that O-acetyltransferase was only partly required for the expression of mutagenic potency of these compounds. 2-Aminocarbazole was a weak direct-acting mutagen for TA1538 and TA98. Its activity was strongly increased in the presence of S9 mix, while 3-aminocarbazole became active in these conditions. The acetamido derivatives were consistently less mutagenic than their parent amines. These results show that nitrocarbazoles and aminocarbazoles behave as reactive frameshift mutagens, acting mainly through the formation of esterified hydroxylamines. The very low activity of 4-nitrocarbazole might be related to an orientation of the nitro group perpendicular to the aromatic ring.