Modulatory effects following subchronic stimulation of brain 5-HT7-R system in mice and rats.

The serotonin receptor 7 (5-HT7-R) plays important functional roles in learning and memory, in regulation of mood and circadian rhythmicity. LP-211 is a new selective agonist, belonging to 1-arylpiperazine category. We report studies aimed to evaluate the modulatory effect of a subchronic regimen on behavioral/molecular parameters. At low dose [0.25 mg/kg intraperitoneally (i.p.)], LP-211 induced a 6-h anticipated wake up in adult mice (with no temporal landmark by constant light), acting as nonphotic stimulus for 'internal clock' resetting. In standard 12:12-h light/dark cycle, a subchronic effect (5-6 days at 0.25 mg/kg, once per day) was observed: delayed wake up, reduced peak of locomotor activity and no evidence for brain cellular proliferation after ex vivo analysis. Other studies in rats were aimed to investigate long-term effects of developmental LP-211 administration into adulthood. Subchronic LP-211 (0.125 mg/kg i.p. once per day during the prepuberal phase) reduced l-glutamate, N-methyl-d-aspartate receptor 1 and dopamine transporter within the ventral striatum. With LP-211 (0.25 mg/kg i.p. once per day during the postpuberal phase), clear reductions were observed in the immunoreactivity of serotonin transporter and dopaminergic D2 receptors in the ventral and dorsal striatum, respectively. Subchronic LP-211 in rats and mice appears to be a suitable tool for studying the role of 5-HT7-R in sleep disorders, emotional/motivational regulations, attentive processes and executive functions.

Quinoline tricyclic derivatives. Design, synthesis and evaluation of the antiviral activity of three new classes of RNA-dependent RNA polymerase inhibitors.

In this study three new classes of linear N-tricyclic compounds, derived by condensation of the quinoline nucleus with 1,2,3-triazole, imidazole or pyrazine, were synthesized, obtaining triazolo[4,5-g]quinolines, imidazo[4,5-g]quinolines and pyrido[2,3-g]quinoxalines, respectively. Title compounds were tested in cell-based assays for cytotoxicity and antiviral activity against RNA viruses representative of the three genera of the Flaviviridae family, that is BVDV (Pestivirus), YFV (Flavivirus) and HCV (Hepacivirus). Quinoline derivatives were also tested against representatives of other RNA virus families containing single-stranded, either positive-sense (ssRNA(+)) or negative-sense (RNA(-)), and double-stranded genomes (dsRNA), as well as against representatives of two DNA virus families. Some quinolines showed moderate, although selective activity against CVB-5, Reo-1 and RSV. However, derivatives belonging to all classes showed activity against BVDV. Among the most potent were the bis-triazoloquinoline 1m, the imidazoquinolines 2e and 2h, and the pyridoquinoxalines 4h, 4j and 5n (EC(50) range 1-5 µM). When tested in a replicon assay, compound 2h was the sole derivative to also display anti-HCV activity (EC(50)=3.1 µM). In enzyme assays, 1m, 2h, 5m and 5n proved to be potent inhibitors of the BVDV RNA-dependent RNA polymerase (RdRp), while only 2h also inhibited the recombinant HCV enzyme.

3-Aryl-2-[1H-benzotriazol-1-yl]acrylonitriles: a novel class of potent tubulin inhibitors.

During a screening for compounds that could act against Mycobacterium tuberculosis, a series of new cellular antiproliferative agents was identified. The most cytotoxic molecules were evaluated against a panel of human cell lines derived from hematological and solid human tumors. In particular, (E)-2-(1H-benzo[d] [1,2,3]triazol-1-yl)-3-(4-methoxyphenyl)acrylonitrile (1) was found to be of a potency comparable to etoposide and greater than 6-mercaptopurine in all cell lines tested. Accordingly, a synthesis of a new series of (E)-2-(5,6-dichloro-1H-benzo[d] [1,2,3]triazol-1-yl)-3-(4-R-phenyl)acrylonitriles was conducted in order to extend the studies of structure-activity relationship (SAR) for this class of molecules. With the aim to evaluate if 3-aryl-2-[1H-benzotriazol-1-yl]acrylonitriles were able to act like tubulin binding agents, the effects on cell cycle distribution of the most active compounds (1, 2a, 3 and 4) were analyzed in K562 cells. A detailed molecular modeling study of the putative binding mode of this series of compounds on tubulin is also reported.

Involvement of adenosine A1 and A2A receptors in (-)-linalool-induced antinociception.

In recent studies performed in our laboratory we have shown that acute administration of (-)-linalool, the natural occurring enantiomer in essential oils, possesses anti-inflammatory, antihyperalgesic and antinociceptive effects in different animal models. The antihyperalgesic and antinociceptive effects of (-)-linalool have been ascribed to its capacity in stimulating the opioidergic, cholinergic and dopaminergic systems, as well as to its interaction with K+ channels, or to its local anaesthetic activity and/or to the negative modulation of glutamate transmission. Activation of A1 or A2A receptors has been shown to induce antinociceptive effects, and the possible involvement of adenosine in (-)-linalool antinociceptive effect, has not been elucidated yet. Therefore, in the present study, we have investigated the effects of 1,3-dipropyl-8-cyclopentylxanthine (DPCPX), a selective adenosine A1 receptor antagonist and the effects of 3,7-dimethyl-1-propargilxanthine (DMPX), a selective adenosine A2A receptor antagonist on the antinociception of (-)-linalool in mice, measured in the hot-plate test. Both DPCPX (0.1 mg/kg; i.p.) and DMPX (0.1 mg/kg; i.p.) pre-treatment significantly depressed the antinociceptive effect of (-)-linalool at the highest doses tested. These findings demonstrated that the effect of (-)-linalool on pain responses is, at least partially, mediated by the activity of adenosine A1 and A2A receptors.

Glycosyl derivatives of dopamine and L-dopa as anti-Parkinson prodrugs: synthesis, pharmacological activity and in vitro stability studies.

Novel glycosyl derivatives of dopamine and L-dopa (I-IV) are synthesized in order to overcome the problem of blood-brain barrier low permeability of dopamine and of low bioavailability of its precursor L-dopa. Esters synthesized link dopamine and L-dopa, by a succinyl linker, to C-3 position of glucose (I and II) and to C-6 of galactose (II and IV). The chemical and enzymatic stabilities of esters synthesized were evaluated in order to determine both their stability in aqueous medium and their feasibility in undergoing enzymatic cleavage by rat plasma to regenerate the original drug. Furthermore, we have shown the central effects of esters I-IV on classic dopaminergic models, such as morphine induced locomotion and reserpine-induced hypolocomotion. From the result obtained compounds I-IV appeared moderately stable in a pH 7.4 buffered solution and in rat plasma. Furthermore, pharmacological studies showed that both dopamine derivatives (I and II) were equiactive in reversing reserpine-induced hypolocomotion in rats, and both were more active than L-dopa or ester III and IV, while II and III were more potent in reducing morphine-induced locomotion than I and IV. The minimal vascular effects of these derivatives allow us to underline the possibility to use them in pathologies, such as Parkinson disease, characterised by an evident decreasing of dopamine concentration in the brain.

Synthesis and in vitro chemical and enzymatic stability of glycosyl 3'-azido-3'-deoxythymidine derivatives as potential anti-HIV agents.

New glycosyl derivatives of 3'-azido-3'-deoxythymidine (AZT) (1 and 2) were synthesized in order to improve AZT retention in the blood and to guarantee its sustained release, overcoming the necessity of multiple drug administrations. The esters synthesized (1 and 2) link AZT, by a succinyl linker, to the C-3 position of glucose and to C-6 of galactose. Furthermore, the chemical and enzymatic stabilities of esters 1 and 2 were evaluated in order to determine both their stability in aqueous medium and their feasibility to undergo enzymatic cleavage by esterase to regenerate the original drug. The pharmacokinetic profiles of esters 1 and 2, obtained after systemic administration, showed an interesting controlled release, in particular for ester 2, compared to the pharmacokinetic profile of AZT.