Synthesis and cytotoxicity of artemisinin derivatives containing cyanoarylmethyl group

A series of 12alpha-deoxoartemisinyl cyanoarylmethyl dicarboxylates (4a-4o), dicarboxylic acids 12alpha-deoxoartemisinyl ester cyanoarylmethyl amide (5a-5k), and dicarboxylic acids 12alpha-deoxoartemisinyl ester N-methylcyanoarylmethyl amide (6a-6l), showing moderate cytotoxicity against P388 and L1210 cells were prepared. They induced the significant accumulation of L1210 and P388 cells in the G1 phase of the cell cycle. This mechanism of action was quite different from that of the majority of cytotoxic compounds used in the chemotherapy of cancer. Compound 4b possessed better cytotoxicity than the other compounds.

Antitumor agents. Synthesis and biological evaluation of new compounds related to podophyllotoxin, containing the 2,3-dihydro-1,4-benzodioxin system

New compounds with naphtho-fused systems were synthesized and evaluated as antitumor agents. The naphtho-fused systems 6 and 7, synthesized from the hydroxy-acetal, exhibit antitumor activity. The bis(phenylthio) derivatives were considered as possible precursors for lignan lactones (11). The hydroxy-naphthalen 6 showed a significant antineoplastic activity.

Synthesis and binding studies on a new series of arylpiperazino benzazol-2-one and benzoxazin-3-one derivatives as selective D4 ligands

A series of new arylpiperazinomethyl derivatives was designed and studied as potential D4 ligands. The synthesis of these compounds required an original synthetic route. Some of the tested compounds were found to be as potent as clozapine at D4 receptors. Moreover, compounds which displayed a high D2/D4 selectivity ratio (>122) were selected for further pharmacological evaluation.

Synthesis and pharmacological evaluation of imidazoline sites I1 and I2 selective ligands

Several series of 2-aryl or heterocyclic-imidazoline compounds have been prepared and evaluated in vitro as imidazoline sites (I1 and I2) and alpha-adrenergic (alpha1 and alpha2) receptor ligands. Their pKi values indicate that linkage of the imidazoline moiety at the 2-position with an aromatic substituent dramatically decreases alpha-adrenergic affinity. I1 sites are more accessible by phenyl imidazolines substituted by a methyl or a methoxy group at the ortho or meta position. Indeed, 2-(2'-methoxyphenyl)-imidazoline (17) is one of the best I1 ligands ever reported (pKi = 8.53 and I1/I2 > 3388). On the other hand, I2 selectivity increases in the presence of a methyl group in the para position. The original compound, 2-(3'-fluoro-4'-tolyl)-imidazoline (31) is a new potent ligand for the I2 sites with high selectivity (pKi = 8.53 and I2/I1 > 3388).

Novel antitumor artemisinin derivatives targeting G1 phase of the cell cycle

Modification of artemisinin structure led us to the discovery of a novel class of antitumor compounds. These artemisinin derivatives containing cyano and aryl groups showed potent antiproliferative effect in vitro against P388 and A549 cells. This activity was reflected in P388 murine leukemia by an accumulation of cells in G1 phase, and induction of apoptosis.

Synthesis and pharmacological evaluation of analgesic 6-substituted 2(3H)-benzothiazolones

A series of novel 6-substituted-2(3H)-benzothiazolones were synthesized and studied as analgesic agents. Among these compounds, two of them were found to exhibit potent analgesic activity in several in vivo tests (acetic acid writhing, Koster, carrageenan and PGE2 hyperalgesia). In these tests the most active compound of this series, i.e. 6-benzoyl-2(3H)-benzothiazolone (4a) was found to be superior to acetylsalicylic acid and equivalent to glafenine. The present study allows to conclude that 4a represents a new type of antinociceptive agent acting in periphery by inhibiting the cyclo-oxygenase pathway and promoting the release of an opioid peptide.

[Synthesis and antidepressive activity study of aryl and heteroaryl carboxamides of benzylpiperazine]

The synthesis of 44 original amide derivatives of benzylpiperazine and some analogues of befuraline and piberaline is reported. All compounds have been tested as antidepressive agents. According to the tests, amides 1, 24 and mainly 31 (dihydrobefuraline) seem to provide elevated antidepressive activity.

Synthesis and cytotoxic activity of 2-dialkylaminoethylamino substituted xanthenone and thioxanthenone derivatives

The synthesis and biological evaluation of some new pyranoxanthenones and pyranothioxanthenones, substituted with flexible amino side-chains, and their evaluation as potential antitumor agents is described. The cytotoxic activity of the compounds and their eventual selective effect on a phase of the cell cycle were evaluated in vitro, using the murine lymphocytic L1210 leukemia cell line. The new aminoderivatives exhibited highly potent cytotoxicity against the leukemia L1210 cell line when compared to acronycine. All the compounds induced a partial accumulation of cells in the G2 + M phase of the cell cycle.

Isomers of substituted 3-benzo[b]furyl and 3-thienylaminobutyric acids as potent ligands of the GABA-B receptor: synthesis and preparative liquid chromatographic separation

Baclofen (4-amino-3-(4-chlorophenyl)butyric acid) is the only selective agonist for GABA-B receptors. Its R-(-)-enantiomer is about 100 times more active than the S-(+)-enantiomer. In the search for new compounds that bind to GABA-B receptors, it is very important to clarify the structural requirements. The authors report the synthesis and separation of isomers of various 3-heteroaromatic (benzo[b]furan and thiophen) aminobutyric acids. The 4-amino-3-(7-methylbenzo[b]furan-2-yl)butanoic acid is a potent and specific ligand for GABA-B receptors, with an IC50 value of 5.4 microM for the displacement of [3H] GABA.

Semisynthesis and cytotoxicity of styryl-lactone derivatives

The cytotoxicity and the cell-cycle action of altholactone (1), goniofufurone (2), and eight altholactone derivatives (5-12), were determined in vitro on L-1210 cells. Semisyntheses and structure-activity relationships of these compounds are described. The results of this study suggest that the cytotoxicity of altholactone (1), 11-nitro-altholactone (8), and 7-chloro-6,7-dihydroaltholactone (10) is due to the accumulation of the cells in the G2 + M phase of the cell cycle.

6-aminoalkyloxazolo[4,5-b]pyridin-2(3H)-ones: synthesis and evaluation of antinoceptive activity

Series of 6-aminoalkyloxazolo[4,5-b]pyridin-2(3H)-ones incorporating structural modifications both in the alkyl chain and basic amino moiety were tested for their analgesic efficacy and safety in mice and rats. Two of the synthesised compounds, 4a (3-methyl-6-[(4-phenyl-1-piperazinyl)methyl]oxazolo[4,5-b]pyridin-2(3H)-one) and 12a (3-methyl-6¿1-[2-(4-phenyl-1-piperazinyl)ethan-1-ol]¿oxazolo[4,5-b]pyridin- 2(3H)-one) were found to be more potent than aspirin with ED50 values of 26 (16.1-42.4) and 15.5 (11.4-21.2) mg/kg po (mouse, phenylquinone writhing test) respectively and 6 (3.1-9.8) and 5.5 (3.5-8.8) mg/kg po (rat, acetic acid writhing test). Compounds 4a and 12a proved to be potent nonopioid nonantiinflammatory analgesics but unfortunately have sedative properties at relatively low doses (respectively 64 and 16 mg/kg po, mice).

Synthesis and structure-activity relationships of novel naphthalenic and bioisosteric related amidic derivatives as melatonin receptor ligands

A previous paper reported the synthesis of melatonin receptor ligands. In order to complete the structure-activity relationships and to obtain antagonists to the melatonin receptor, a new series of naphthalenic analogues of melatonin have been synthesized. Modifications include deletion of the 7-methoxy group, replacement of the ethylene moiety, replacement of the amidic function by bioisosteres, and replacement of the naphthalenic nucleus by other bicyclic rings. Almost all the structural modifications lead to decreased affinity for the melatonin receptor. However, the N-n propyl urea derivative (27) is a very potent ligand at this receptor (pKi = 14.3). Most interestingly deletion of the methoxy group resulted in the first antagonist in this series. This molecule, compound 12, or N-[2-(1-naphthyl)-ethyl]cyclobutyl carboxamide has been selected for preclinical development.

Novel benzothiazolin-2-one and benzoxazin-3-one arylpiperazine derivatives with mixed 5HT1A/D2 affinity as potential atypical antipsychotics

Since it was known that 5HT properties (5HT1A agonism or 5HT2A antagonism) combined with D2 antagonism may lead to atypical antipsychotic drugs, a series of 19 benzothiazolin-2-one and benzoxazin-3-one derivatives possessing the arylpiperazine moiety was prepared, and their binding profiles were investigated. All tested compounds displayed very high affinities for the 5HT1A and D2 receptors. Therefore, further pharmacological studies were carried out on selected compounds (24, 27, 30, 46, and 47). This evaluation in rats clearly revealed potent antipsychotic properties along with a decrease of extrapyramidal side effects. These derivatives are currently under preclinical development.

Substituted pyrido[3,2-b]oxazin-3(4H)-ones: synthesis and evaluation of antinociceptive activity

A new series of N-substituted pyrido[3,2-b]oxazinones has been synthesized, pharmacologically evaluated, and compared with acetyl salicylic acid. The compound with the maximal combination of safety and analgesic efficacy was 4-¿3-[4-(4-fluorophenyl-1-piperazinyl)propyl]¿-2H-pyrido[3,2-b]-1, 4-oxazin-3(4H)-one (6c) with ED50 values of 12.5 mg/kg po (mouse: phenylquinone writhing test) and 27.8 mg/kg po (rat: acetic acid writhing test), respectively. Compound 6c proved to be more active than aspirin with a safety index of 5.1.

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.

Novel indole-2-carboxamide and cycloalkeno[1,2-b]indole derivatives. Structure-activity relationships for high inhibition of human LDL peroxidation

Series of indole-2-carboxamide and cycloalkeno[1,2-b]indole derivatives were synthesized and evaluated in order to determine the necessary structural requirements for a high inhibition of human LDL copper-induced peroxidation. Various modulations were systematically performed on the indole and cycloalkeno[1,2-b]indole nuclei as well as on the carboxamide moiety. The best compounds (3c, 3e, 7c, 7f, 7h, 7g, and 7o) are between 5 and 30 times more active than probucol itself. Two of these compounds (3c and 7o) were selected for complementary in vitro and in vivo investigations, which have shown additional properties of interest for the treatment and the prevention of atherosclerosis injuries. Compound 3c was found to have some antiinflammatory properties while compound 7o was proved to protect endothelial cells from the direct cytotoxicity of oxidized LDL with some additional calcium channel blocking properties.

3-amino-3,4-dihydro-2H-1-benzopyran derivatives as 5-HT1A receptor ligands and potential anxiolytic agents. 2. Synthesis and quantitative structure-activity relationship studies of spiro[pyrrolidine- and piperidine-2,3'(2'H)-benzopyrans]

In continuation of our work on 3-amino-3,4-dihydro-2H-1-benzopyran derivatives with high affinity for 5-HT1A receptors, we have prepared rigid spirobenzopyran analogues designed from the pharmacophore models of Mellin and selected via a quantitative structure-activity relationship approach mainly based on similarity indices. A series of spiro[pyrrolidine- and piperidine-2,3'(2'H)-benzopyrans] with various substitutions on the aromatic ring as well as on the extracyclic spiranic nitrogen atom were then synthesized and evaluated for their serotonergic and dopaminergic activities. Good correlation between the predicted and the experimental binding values was observed with an average difference of 0.2 unit on log(IC50). Affinities for the 5-HT1A receptors were in the nanomolar range for the best compounds ((+)-11a,23) with a high selectivity versus other 5-HT (5-HT1B, 5-HT2, 5-HT3) or dopamine (D1, D2) receptor subtypes. As for the 3-amino-3,4-dihydro-2H-1-benzopyran series, the dextrorotatory enantiomer (+)-11a showed better affinity and selectivity for 5-HT1A receptors than its levorotatory analogue (-)-11a. Compound (+)-11a proved in vitro to be a full agonist and in vivo to be active in various comportmental tests predictive of psychotropic activity, such as the forced swim test and the tail suspension test, and is currently under complementary investigations.

Effects of S20787 on pHi-regulating mechanisms in isolated rat ventricular myocytes

Intracellular pH (pHi) regulation in the heart relies on the activity of three membrane mechanisms: the Na+/H+ exchange and an Na+, HCO3(-)-dependent transport, both activated after an acid load, and the Cl-/HCO(3-) exchange, activated by an intracellular alkalinization. Whereas several specific inhibitors of Na+/H+ exchange exist, distinguishing between the two HCO3(-)-dependent mechanisms remains difficult, especially near the steady state, because of the lack of specific inhibitors. To detect one such inhibitor, we tested the effects of S20787 on pHi regulation in the rat isolated ventricular myocytes. Intracellular pH was recorded with the fluorescent probe carboxy-SNARF-1. The NH4Cl (10 mM) prepulse method was used to induce an acid load to activate the dual acid extrusion system; Cl-/HCO3- exchange was activated with the acetate (40 mM) prepulse method. Our results showed that (a) a high dose (5.10(-6) M) of S20787 did not change intracellular intrinsic buffering power, beta i; (b) the dual acid extrusion system was unaffected by S20787 in the concentration range of 10(-11)-10(-6) M; and (c) S20787 partially inhibited (approximately 50%) the activity of Cl-/HCO3- exchange in a dose-dependent manner, with an IC50 of 8.8 x 10(-10) M. This inhibitory action of S20787 did not change the steady-state pHi after 5-10 min application. Our results demonstrate that S20787 is a specific and potent partial inhibitor of Cl-/HCO3- exchange in cardiac cells.

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.

N-substituted aminohydroxypyridines as potential non-opioid analgesic agents

A series of new N-substituted aminohydroxypyridines have been synthesized, pharmacologically evaluated and compared with their N-substituted oxazolopyridone analogs. The compound with the maximal combination of safety and analgesic efficacy was 3-[2-[4-(4-fluorophenyl)-1-piperazinyl]ethyl]amino-2-hydroxypyridine (compound 10a), with ED50 values 0.4 mg kg-1 po (mouse: phenylquinone writhing test) and 0.5 mg kg-1 po (rat: acetic acid writhing test). Compound 10a possesses a potent non-opioid antinociceptive activity with moderate anti-inflammatory properties.

N-substituted oxazolo[5,4-b]pyridin-2(1H)-ones: a new class of non-opiate antinociceptive agents

A series of 1-(aminoalkyl)- and 1-[(4-aryl-1-piperazinyl)alkyl]oxazolo[5,4-b]pyridin-2(1H)-one derivatives of oxazolo[5,4-b]pyridin-2(1H)-one, incorporating modifications to the length of the alkyl side chain and to the amino or 4-aryl-1-piperazinyl substituents, were tested for safety and analgesic efficacy in mice and rats. Some compounds with 4-(substituted or nonsubstituted phenyl)-1-piperazinyl substituents and a 3-4-carbon alkyl side chain had significantly greater analgesic activity than that of the oxazolo[4,5-b]pyridin-2(3H)-one analogs. To reduce the metabolic N-dealkylation of the piperazine observed in our previous work on oxazolo[4,5-b]-pyridin-2(3H)-ones, analogs of the most active compounds with steric hindrance on the alkyl side chain were prepared and tested. The compound with the maximal combination of safety and analgesic efficacy was 1-[[4-(4-fluorophenyl)-1-piperazinyl]propyl]oxazolo[5,4-b]pyridin- 2(1H)-one (compound 3b), with ED50 values of 5.6 mg/kg po (mouse, phenylquinone writhing test) and 0.5 mg/kg po (rat, acetic acid writhing test). Compound 3b is a potent, rapid-acting, non-opioid, nonantiinflammatory analgesic with low acute toxicity and sustained effect.

Synthesis and structure-activity relationships of novel naphthalenic and bioisosteric related amidic derivatives as melatonin receptor ligands

A series of N-naphthylethyl amide derivatives were synthesized and evaluated as melatonin receptor ligands. The affinity of each compound for the melatonin receptor was determined by binding studies using [2-125I]iodomelatonin on ovine pars tuberalis membrane homogenates. Structure-activity relationships led to the conclusion that naphthalene is a bioisostere of the indole moiety of melatonin. Moreover it appears that the affinity is strongly affected by the size of the substituent of the nitrogen of the amidic function. Many of these ligands give biphasic dose-response curves which suggests that there may be two melatonin receptor subtypes within the ovine pars tuberalis cells. The replacement of naphthalene by benzofuran or benzothiophene did not strongly alter the affinity for the melatonin receptor. In contrast, the benzimidazole analogue was a poor ligand. Compound 7, the naphthalenic analogue of melatonin, a selective ligand of the melatonin receptor and an agonist derivative, has been selected for clinical development.

3,4-Dihydro-3-amino-2H-1-benzopyran derivatives as 5-HT1A receptor ligands and potential anxiolytic agents. 1. Synthesis and structure--activity relationship studies

A series of 3,4-dihydro-3-amino-2H-1-benzopyran derivatives were prepared in order to determine the necessary structural requirements for good affinity for 5-HT1A receptors and high selectivity versus other receptors. Modifications of the extracyclic amino substituents, the length of the alkyl side chains, and their substituents were explored. The best compounds (9g, 9k, 15b, 15d) possess imido or sulfonamido functional groups with a preferential length of four methylenes for the side chain. After resolution, the dextrorotatory enantiomers showed better affinity and selectivity for 5-HT1A receptors. These compounds have been proven to be full agonists. 9g and its enantiomers showed anxiolytic activity in vivo in various comportemental models. The compound (+)-9g is currently under clinical investigation.

[New naphthalenic ligands of melatoninergic receptors]

Twenty three naphthalenic bio-isosteres of melatonin have been synthesized. The main structural variations concerned the acylamino substituents of the side chain and the alkoxy group on the 7-position of the naphthalene. Some of these compounds show greater affinity than melatonin itself for the melatonin receptor. The results of this study provide new informations on the structure affinity relationships and on the mode of interaction at the melatonin binding site.

[Synthesis and pharmacologic study of 6-(amino-2 ethyl) benzoxazolinones]

Reaction of various amines on 6-(2-bromoethyl)benzoxazolinone or its N-methylated derivative provided eleven new 6-substituted aminoalkyl analogues. In a pharmacological evaluation, several compounds bearing an arylpiperazinic moiety were found to possess significant effects on arterial blood pressure and on the central nervous system; two of them showed interesting analgesic activity.

[Alkyl-6-benzoxazolinones. A chemical and pharmacodynamic study]

A series of 6-alkylbenzoxazolinones was synthesized by reduction of corresponding acyl derivatives. Two reduction processes were used, Clemmensen reduction and triethylsilane-trifluoroacetic acid reduction, but only the latter represents a general procedure for synthesis of alkyl derivatives. Pharmacological study shows that reduction of the carbonyl group is accompanied by a decrease of analgesic activity with appearance of a psycholeptic profile.