Quinolizidinyl derivatives of bi- and tricyclic systems as potent inhibitors of acetyl- and butyrylcholinesterase with potential in Alzheimer's disease.

On the pattern of the potent and selective butyrylcholinesterase (BChE) inhibitors ethopropazine and Astra1397, sets of quinolizidinyl derivatives of bi- and tricyclic (hetero)aromatic systems were studied as dual, or BChE-selective inhibitors. All compounds exhibited activity against both cholinesterases, but inhibition of BChE was generally stronger, with submicromolar IC50 values for most of them (e.g. 15: IC50 versus BChE=0.15 µM; SI=47). However, in a subset of quinolizidinyl derivatives of 6-hydroxycoumarin an inverted selectivity for acetylcholinesterase (AChE) was observed (e.g. 46: IC50 versus AChE=0.35 µM; SI=0.06). Docking studies furnished a sound interpretation of the observed different enzyme activity. Several of the studied compounds have shown, in the past, additional pharmacological properties (as antagonism on presynaptic muscarinic autoreceptor; inhibition of enkephaline aminopeptidase and antipsychotic activity) of some relevance in Alzheimer's disease, and may, therefore, represent hits for the development of interesting single-entity multi-target drugs.

New benzamide-derived 5-HT3 receptor antagonists which prevent the effects of ethanol on extracellular dopamine, and fail to reduce voluntary alcohol intake in rats.

A set of substituted benzamides, characterized by the presence of a bulky quinolizidine moiety, were subjected to binding assays for 5-HT3 and D2 receptors on membranes obtained from the bovine area postrema ([3H]-GR65630) and the rat striatum ([3H]-spiperone) respectively. These benzamides resulted unsuitable for the recognition of D2 receptors, while a few of them, devoid of 5-HT4 receptor activity, had consistent affinity for central 5-HT3 receptors, inhibiting also potently the ethanol-induced dopamine efflux from the mesolimbic dopamine terminal region. However they failed in attenuating voluntary alcohol consumption in rats, as observed with several other chemically unrelated 5-HT3 antagonists. Thus the 5-HT3-mediated inhibition of alcohol-induced striatal release of dopamine by substituted benzamides is not a requisite for affecting ethanol intake.

Synthesis and preliminary pharmacological investigation of N-lupinyl-2-methoxybenzamides.

A set of eleven N-lupinyl-2-methoxybenzamides, variously substituted on the benzene ring, together with two related compounds, were prepared and subjected to a large pharmacological screening, though not all compounds were tested in each assay. Compounds 1-10 displaced [125I]-iodosulpride from D2 receptors only at very high concentration (IC50 > 5 microM). At micromolar concentrations, compounds 1, 12, and 13 inhibited the binding of [3H]-pirenzepine and of [3H]-di-o-tolylguanidine respectively on M1 and sigma receptors; in the last case comp. 13 was more active (IC50 = 0.3 microM) than the epimeric 1. Compounds 1-10 at 10-25 mg/kg p.o. protected mice against electroshock induced seizures; 1-sulpiride was inactive in this test. Compound 1 exhibited in three tests antiarrhythmic activity superior to that of quinidine and lidocaine. The same antagonized, in vitro, guinea pig ileum contractile response induced by several agents, and enhanced the intestinal transit rate in mice (charcoal bolus test). The last activity (shown in lower degree also by comp. 5) could be related to agonism with 5HT4 receptors, as could be expected for orthopramides with conformationally restricted side chains. This possibility is presently under investigation.

Detection and mass spectrometric characterization of the major urinary and fecal metabolites of 9-methyl-1,2,3,4,6,7,12,12b-octahydroindolo[2,3-a]-quinolizine in the rat.

The metabolic fate of 9-methyl 1,2,3,4,6,7,12,12b-octahydroindolo[2,3-a]quinolizine (MIQ), a compound with promising pharmacological action on the CNS system, was investigated in the rat after an oral dose of 200 mg/kg, the maximal tolerated dose. Urine and feces were collected, exhaustively extracted with organic solvents and the metabolites detected by TLC analysis. The structures of the isolated metabolites were characterized by several mass spectrometry techniques (FD, EI, CI) and, in some cases, confirmed by synthesis. The major metabolic pathways of MIQ in the rat involve: C-oxidation of the methyl group in position 9 to a primary alcohol and to a carboxylic acid, N-oxidation of basic nitrogen and C-oxidation of the quinolizidine nucleus, probably at position 7.

Poor interaction of some quinolizidine derivatives with dopamine D1- and D2- type receptors.

The displacement of [3H]SCH-23390 and of [3H]spiperone from striatal, dopamine D1- and D2-type receptors by several quinolizidinyl-derivatives of bi- and tricyclic systems was investigated. All tested compounds did not affect SCH-23390 binding and exhibited only weak activity on spiperone binding to D2 binding sites (Ki = 1.9 microM). Therefore the good deconditioning activity (CAR blockade in rats) of 6-chloro-1-lupinyl-3-methyl-quinoxalinone (18) must rely on interactions with other kinds of receptors.

Synthesis and antimicrobial activity of arylazoenamines.

The possibility to obtain new arylazoenamines endowed with antifungal activity was examined by reacting with acids the arylhydrazones of several keto- and aldo-tert, amines as dimethyl-3-aminoacetone, 3-quinuclidinone, 1-methyl-3-piperidone and 2-formyl-1-methylpyrrolidine. The reaction was successful only in the last two cases. From each 1-methyl-3-piperidone arylhydrazone two isomeric arylazoenamines were formed, which were identical with those obtained from the analogous arylhydrazone of 2-formyl-1-methylpyrrolidine. The structure of these compounds was settled on the ground of UV, IR, NMR and mass spectra and confirmed by means of X-ray analysis. A mechanism is proposed for the formation of arylazoenamines through the contraction of piperidine ring and enlargement of the pyrrolidinic one. The prepared compounds [3-arylazo-1-methyl-delta 2-piperideines 17 and 1-methyl-2(arylazo)methylene pyrrolidines 18 exhibited only a very weak antibacterial activity, but were moderately active against several Candida species and other yeast-like fungi.

Preparation and antimicrobial activity of 1-arylazo-3,4,6,7,8,9-hexahydroquinolizines.

A set of 1-(R-arylazo)-3,4,6,7,8,9-hexahydroquinolizines, bearing different substituents on the benzene ring, were prepared and tested for antimicrobial activity. These compounds exhibit only a very weak activity against gram-positive and gram-negative bacteria, but are fairly active against several Candida species and other yeast-like fungi.

Synthesis and antileukemic activity of 1-[(quinolizidinylalkyl)amino]4/7-R-thioxanthen-9-ones.

Fifteen 1-(quinolizidinylalkyl)amino derivatives of thioxanthenone bearing different substituents on position 4 and 7 were prepared and tested in mice against lymphocytic leukemia P 388. These compounds were inactive or displayed only borderline activity (compounds 1, 10, 15).

Quinolizidine derivatives as potential antitumoral agents.

The activity against lymphocytic leukemia P 388 has been evaluated for thirteen compounds bearing a quinolizidine moiety bound respectively to a phenothiazine nucleus or other isosteric tricyclic systems (12-17), as well to a quinoxalinone (18-20) or an indole (21-24) nucleus. All tested compounds resulted inactive.

[Formulation and antileukemic activity of quinolizidinylalkylaminic derivatives of naphthoquinone and anthraquinone]. / Preparazione e attività antileucemica di derivati chinolizidinil alchilamminici del naftochinone e dell'antrachinone.

By reacting three quinolizidinylalkylamines with 1,4-naphtoquinone, 2,3-dichloronaphto-1,4-quinone and 1-chloroanthraquinone nine compounds were obtained which are of interest as antitumoral, antiviral, antibacterial and antiparasitic agents. These compounds, so far, have been tested against lymphocytic leukemia P 388 in mice and found inactive.

[Preparation and antileukemic activity of quinolizidinylalkyl-derivatives of 4-aminoquinoline and 9-aminoacridine]. / Preparazione e attività antileucemica di chinolizidinil-alchil derivati della 4-amminochinolina e della 9-amminoacridina.

By reacting three quinolizidinylalkylamines with 4,7-dichloroquinoline and 6,9-dichloro-2-methoxyacridine six derivatives of 4-aminoquinoline and 9-aminoacridine were obtained. These compounds, which are of interest as potential antibacterial, antiprotozoarian, anti-helminthic and antitumoral agents, so far have been tested against lymphocytic leukemia P 388 and found to be inactive.

[Synthesis and pharmacologic activity of 9-R-octahydroindolo[2,3-a]quinolazine]. / Sintesi ed attività farmacologica di 9-R-ottaidroindolo [2,3-a]chinolizine.

By acid induced cyclization of quinolizidin-1-one 4-R-phenylhydrazones several derivatives of 1,2,3,4,6,7,12,12b-octahydroindolo[2,3-a]quinolizine (1), bearing a substituent on position 9, were prepared. When R = Cl this reaction gave rise also to a red-orange compound to which the structure (V) of 1-(p-chloro)phenylazo-3,4,6,7,8,9-hexahydroquinolizine was assigned. Substances (1 b)-(1-f) were tested for spontaneous locomotor, muscle relaxant, analgesic, antiinflammatory, diuretic and cardiovascular activities and for influence on pentylentetrazole and sodium pentobarbital actions. Interesting levels of activity were exhibited in several cases.

[Synthesis and pharmacologic activity of 3-quinolizidine-1'-yl-5-R-indoles]. / Sintesi ed attività farmacologica di 3-chinolizidin-1'-il-5-R-indoli.

By acid action on the mixture of homolupinal diethylacetal and arylhydrazines several 3-quinolizidin-1'-yl-5-R-indoles (III a - III e) were prepared. The homolupinal diethylacetal, whose hydrolysis gives rise to the unknown aldehyde, was obtained through the action of lupinylmagnesium chloride on diethylphenylorthoformate. Compounds (III) were subjected to wide pharmacological screening; all of them exhibited calcium blocking, negative cardioinotropic and diuretic activities, while single compounds showed antiinflammatory (III d), anticonvulsant and hypoglycemic (III e) activities.

[Quinolizidinyl derivatives of tricyclic systems]. / Chinolizidinilderivati di sistemi triciclici.

Since the pharmacological screening of several lupinyl- and lu lupinyldene derivatives of three-ring systems showed several interesting activities on the C.N.S., new investigations have been undertaken in order to understand the neurochemical mechanisms underlying such activities (influence on the uptake of choline, norepinephrine and serotonin by isolated rat brain synaptosomes). Thus the series of lupinyl derivatives has been completed with N-lupinyl-2-chloroiminodibenzyl and N-lupinyl-2,3-hexamethyleneindole; moreover, for all the three-ring systems so far considered, the corresponding epi-lupinyl- and epi-lupinylidenderivatives have been prepared in order to check the significance of the steric relationships between the quinolizidine ring and the tricyclic systems. The latter compounds differ from those formerly described for the equatorial position (rather than axial) of the methylene or methine group joining the quinolizidine nucleus to the three-ring systems.

Formation of mutagenic derivatives from nitrite and two primary amines.

Sodium nitrite and two primary aromatic amines, viz. amino antipyrine (AAP) and aniline, were preincubated in vitro with human gastric juice. The resulting derivatives -- presumably diazonium salts -- were directly mutagenic in the Salmonella test. The mutagenic response was more pronounced in the case of AAP, while toxic effects narrowed the range of activity of the aniline derivative. These patterns are consistent with the findings of independent colorimetric analyses, showing that the AAP derivative is more stable at 37 degrees C than the aniline derivative.

Effect of human gastric juice on the mutagenicity of chemicals.

10 mutagens were assayed in the Salmonella test after a pre-incubation step with human gastric juice. Such treatment affected the activity of 4 compounds, with different mechanisms, either in the sense of deactivation (sodium azide and sodium dichromate), of stabilization (captan), or even of potentiation (ICR-170). Conversely, the mutagenicity of other compounds (folpet, sodium nitrite, ICR-191, nitrofurantoin and a related drug) was unchanged. The stability of 2 carcinogens requiring metabolic activation, namely benzo[a]pyrene and aflatoxin B1, provided evidence that pre-incubation of compounds with gastric juice is compatible with the subsequent addition of liver post-mitochondrial preparations, thus reproducing in vitro 2 consecutive metabolic steps occurring in the organism. These findings lead us to report an improved correlation between assays in vivo and in vitro, in particular by explaining the lack of carcinogenicity of some mutagens introduced orally or by gastric intubation. Therefore, the Salmonella/gastric juice test is proposed as an additional assay for predicting the potential health hazards of chemicals.

[Quinolozidinylalkylamines with antihypertensive activity]. / Chinolizidinilalchilammine ad azione antiipertensiva.

Since lupinylamine [(I); R = H] exhibits hypotensive activity, mainly due to ganglionic blocking properties, and it is known that a high degree of steric hindrance around the basic function of other ganglioplegic amines is of paramount importance for optimal activity, several guinolizidine derivatives were prepared. They differ in the length of the alkyl chain connected to the ring and in the position of the amino group along the chain. Some N-substituted derivatives of 2-quinolizidin-1'alpha-yl-ethylamine (II) together with O-lupinylhydroxylamine and 2-quinolizidin-1'beta-yl-ethylamine, respectively isosteric and epimeric to it, were also prepared. When administered orally to spontaneously hypertensive rats, the amines (II), (III) and (XI) produced high and long-lasting antihypertensive activity, while the remaining compounds so far tested were inactive or had only modest effect on blood pressure. Compared with alpha-methyl-DOPA, amine (II) appears to be approximately two to three times as potent. The antihypertensive activity of (II) appears to be linked to glanglionic blocking properties, since this amine proved 1,2 times as potent as mecamylamine in the inhibition of cat nictitating membrane response to stimulation of the preganglionic sympathetic nerve.