Excitatory amino acids in the forebrain of the Naples high-excitability rats: neurochemical and behavioural effects of subchronic D-aspartate and its diethyl ester prodrug.

The excitatory amino acids (EAA) L-glutamate (L-Glu), L-aspartate (L-Asp) and D-aspartate (D-Asp) are thought to play a neurotransmitter/neuromodulator role in neuronal communications. Recently, a high level of EAA L-Glu, D- and L-Asp isomers has been found in the forebrain of Naples high-excitability (NHE) rat line that models the mesocortical variant of Attention-Deficit Hyperactivity Disorder (ADHD). The aim of this study was to assess the functions of D-Asp using two forms, i.e. free D-Asp or D-Asp diethyl ester (DEE) as prodrug, on brain and behaviour. Thus, prepuberal rats were given, for two weeks daily, an i.p. injection of D-Asp or DEE or vehicle. Then rats were exposed to two spatial novelties i.e. Làt and radial Olton maze. Behaviour was monitored for indices of activity, non-selective attention (NSA), selective spatial attention (SSA) and emotional reactivity. L-Glu and D- and L-Asp were detected by HPLC in cognitive and non-cognitive brain areas such as prefrontal cortex, striatum, hippocampus and hypothalamus. Results indicate that subchronic D-Asp or DEE (i) reduced EAA levels in the NHE and increased it in the random-bred controls (NRB) rats, (ii) in the Làt-maze D-Asp increased horizontal activity in NHE but DEE decreased it in NRB rats, (iii) in the Olton maze D-Asp and DEE decreased vertical activity in NHE and NRB rats respectively, (iv) D-Asp impaired attention only in NRB decreasing number of arms visited before first repetition. Therefore, data demonstrate differential effects of prepuberal subchronic D-Asp and DEE that may be related to different basal EAA levels in NHE and NRB rats.

Galactosylated dopamine enters into the brain, blocks the mesocorticolimbic system and modulates activity and scanning time in Naples high excitability rats.

Pathological conditions, such as Parkinson's disease and attention deficit hyperactivity disorder, have been linked to alterations of specific dopamine (DA) pathways. However, since exogenous DA does not cross the blood-brain barrier, DA levels can be modulated e.g. by DA precursors or DA reuptake blockers. Hereby histochemical, analytical and behavioral evidence shows that a galactosylated form of DA (GAL-DA) carries DA into the brain, thus modulating activity and nonselective attention in rats. To this aim adult male rats of the Naples high-excitability (NHE) and random bred controls (NRB) lines were given a single i.p. injection of GAL-DA (10 or 100 mg/kg). Three hours later the behavior was videotaped and analyzed for horizontal activity, orienting frequency and scanning duration. The dose of 100 mglkg of GAL-DA reduced by 25% the horizontal activity in NHE rats, mainly in the first part of the testing period. No effect was observed on orienting frequency or on scanning duration. However, GAL-DA 100 mg/kg was associated with longer rearing episodes in the second part of the testing period in NHE rats. In parallel experiments histochemistry with a galactose-specific lectin showed 10% increase in galactose residues into the striatum between 0.5 and 3.0 h. To quantify the level of GAL-DA, its metabolite DA-succinate and DA in the prefrontal cortex, neostriatum, and cerebellum, rats were killed 2.0 h after the injection of prodrug. Mass high performance liquid chromatography (HPLC) was used for analysis of GAL-DA and DA succinate whereas electrochemical HPLC for DA. Both HPLC techniques demonstrate that GAL-DA carries and releases DA into the brain. Specifically 100 mg/kg of GAL-DA increased DA level in the striatum in the NHE rats only. Moreover, DA in the mesencephalon (MES) was correlated positively with striatal and prefrontal cortex DA in NHE rats. In contrast DA in the MES was negatively correlated with striatal DA in NRB. GAL-DA disrupted these correlations in both rat lines. Thus, this new DA prodrug may modify DA neurotransmission and might have a potential clinical application.

Sol-gel processing of anti-inflammatory entrapment in silica, release kinetics, and bioactivity.

Controlled and local drug-delivery systems for anti-inflammatory agents are drawing increasing attention for possible pharmaceutical and biomedical applications, because of their extended therapeutic effect and reduced side effects. A single-step sol-gel process was used to precipitate silica microspheres containing Ketoprofen, Indomethacin, Ketorolac tris salt, or Triamcinolone acetonide, for controlled drug delivery applications. The amorphous nature of the gels was ascertained by X-ray diffraction analysis. Release kinetics in a simulated body fluid (SBF) has been subsequently investigated. The amount of drug released has been detected by UV-vis spectroscopy. The pure anti-inflammatory agent exhibited linear release with time, while sol-gel silica-entrapped drugs were released with a logarithmic time dependence, starting with an initial burst effect followed by a gradual decrease. Finally, SEM micrography and EDS analysis showed the formation of a hydroxyapatite layer on the surface of the samples soaked in SBF. All the materials showed good release and therefore could be used as drug-delivery systems.

Galactosilated dopamine increases attention without reducing activity in C57BL/6 mice.

Different strategies can be used to carry dopamine into the brain such as L-Dopa precursors or galactosilated form of DA (GAL-DA). The aim of this study was to investigate whether GAL-DA would reduce hyperactivity and increase non-selective attention (NSA) in a mouse model of attention deficit hyperactivity disorder (ADHD), as, i.e. C57BL/6 as did in NHE rats. Here we report that GAL-DA increases NSA in a spatial novelty in C57BL/6 mice. They received a single i.p. injection of GAL-DA (10 mg/kg or 100 mg/kg) or equimolar galactose vehicle. Another mouse strain the Swiss albino was introduced as inbred control group. Three hours after last injection mice were tested in a Làt-maze for 30-min. Behaviour was analyzed for horizontal (traveled distance) and vertical activity (orienting frequency and scanning durations) which shares cognitive and non-cognitive nature, respectively. Ten milligram per kilograms of GAL-DA, increases scanning duration in C57BL/6 mice. Thus a low dose of GAL-DA increases NSA without reducing hyperactivity in this mouse model of ADHD.

Characterization, bioactivity and ampicillin release kinetics of TiO2 and TiO24SiO2 synthesized by sol-gel processing.

Local drug delivery of antimicrobics by sustained release delivery system can be used to treat periodontal disease. Advantages of these systems may include maintaining high levels of antibiotic in the gingival crevicular fluid for a sustained period of time and ease of use with high patient acceptance. The materials used are TiO(2) and TiO(2)4SiO(2), mixed with sodium ampicillin, a broad-spectrum antibiotic, have been synthesized by sol-gel method. The amorphous nature of the gels was ascertained by X-ray diffraction analysis. Release kinetics in a simulated body fluid (SBF) have been subsequently investigated. The amount of sodium ampicillin released has been detected by UV-VIS spectroscopy and SEM. The release kinetics seems to occur in more than one stage. HPLC analysis has also been taken to ensure the integrity of ampicillin after the synthetic treatment. Finally, SEM micrographs and EDS analysis showed the formation of a hydroxyapatite layer on the surface of the samples soaked in SBF. Both the materials showed good release and could be used as drug delivery bioactive systems. High antimicrobial effects of samples against Escherichia coli and Streptococcus mutants were found.

In vitro and in vivo evaluation of polyoxyethylene esters as dermal prodrugs of ketoprofen, naproxen and diclofenac.

Novel polyoxyethylene esters of ketoprofen (1(a-e)), naproxen (2(a-e)) and diclofenac (3(a-e)) were synthesized and evaluated as potential dermal prodrugs of naproxen, ketoprofen and diclofenac. These esters were obtained by coupling these drugs with polyoxyethylene glycols by a succinic acid spacer. The aqueous solubilities, lipophilicities and hydrolysis rates of esters 1(a-e), 2(a-e) and 3(a-e) were determined in a buffered solution and in porcine esterase. The permeation of these prodrugs through excised human skin was studied in vitro. Furthermore we investigated the in vivo topical anti-inflammatory activity of esters 1(d), 2(e) and 3(e), which showed the best in vitro profile, evaluating the ability of these compounds to inhibit methyl nicotinate (MN)-induced skin erythema on healthy human volunteers. Esters 1(a-e), 2(a-e) and 3(a-e) showed good water stability and rapid enzymatic cleavage and their hydrolysis rates, both chemical and enzymatic, were not significantly affected by the length of the polyoxyethylenic chain used as promoiety. Concerning in vitro percutaneous absorption studies, only esters 1(d-e), 2(d-e) and 3(c-e) showed an increased flux through stratum corneum and epidermis membranes compared to their respective parent drugs. In vivo results showed an interesting delayed and sustained activity of esters 1(d) and 3(e) compared to the parent drugs. In conclusion polyoxyethylene glycols could prove to be suitable promoieties for ketoprofen, naproxen and diclofenac design since esters 1(d-e), 2(d-e) and 3(c-e) showed some requirements (chemical stability, enzymatic lability and an increased skin permeation) needed to obtain successful dermal prodrugs. Furthermore, was observed an appreciable and sustained in vivo topical anti-inflammatory activity of esters 1(d) and 3(e), compared to the parent drugs, using MN-induced erythema in human volunteers as inflammation model.

Synthesis of substituted N-(4-piperidyl)-N-(3-pyridyl)amides with antiarrhythmic activity. Note 1.

The synthesis of analogues of N,2-diphenyl-N-(4-piperidyl)acetamide endowed with antiarrhythmic activity is reported. Benzoyl, cinnamoyl, acetyl and propionyl groups replace the phenacyl group as N-acyl substituent, while pyridine replaces benzene as aromatic ring bound to the amide nitrogen. The title compounds were evaluated for antiarrhythmic activity on experimental arrhythmias induced by aconitine in rats. The presence of a n-propyl chain and an unsubstituted cinnamoyl moiety (1j) gives the highest protection against aconitine induced extrasystoles while the best efficacy against lethal effects is due to the presence of a n-propyl chain and an acetyl moiety (1m).

Synthesis and characterisation of poly(D,L-lactic acid)-idoxuridine conjugate.

A new polymeric prodrug was prepared coupling 5-iodo-2'-deoxyuridine (IDU) to poly(d,l-lactic acid) (PLA) via a succinic acid spacer. The PLA-IDU conjugate was characterised by thermal analysis, IR and 1H and 13C NMR spectroscopy. The IDU content (0.024 mequiv.g-1 of PLA) was consistent with the carboxylic acid endgroup present in the polymer sample (0.025 mequiv.g-1 of polymer). The PLA-IDU conjugate was susceptible to degradation in biological environments containing esterase, whereas IDU was not detected by chemical hydrolysis in pH 7.4 phosphate buffer. The conjugate should be used to prepare injectable microspheres and nanospheres containing IDU chemically coupled to the polymer carrier.

Research on heterocyclic compounds, Part 40. 2-Phenylimidazo[1,2-a]pyridine-3-carboxylic acid derivatives: synthesis and antiinflammatory activity.

A series of 2-phenylimidazo[1,2-a]pyridine-3-carboxylic esters, acids, and amides were synthesized and pharmacologically tested in order to evaluate their antiinflammatory and analgesic activity and their ulcerogenic action on the gastro-intestinal tract. The most active member of this series of compounds was found to be 6-methyl-2-phenylimidazo[1,2-a]pyridine-3-carboxylic acid (5c).

Synthesis and pharmacological activity of imidazo[2,1-b]benzothiazole acids.

We have prepared twelve imidazo[2,1-b]benzothiazole carboxylic and acetic acids by reaction of substituted 2-aminobenzothiazoles with ethyl bromopyruvate and 4-chloroacetoacetate, respectively. The acids, obtained from esters by hydrolysis, were tested for their antiinflammatory, analgesic and ulcerogenic activities.

Research on heterocyclic compounds, XXIX. Synthesis and antiinflammatory activity of imidazo[1,2-a]pyrazine derivatives.

The reaction in anhydrous ethanol of some substituted 2-aminopyrazines with ethyl 2-benzoyl-2-bromoacetate or with ethyl 3-bromo-4-oxopentanoate afforded a group of ethyl 2-phenylimidazo[1,2-a]pyrazine-3-carboxylates and a group of ethyl 2-methylimidazo[1,2-a]pyrazine-3-acetates, respectively. The corresponding acids obtained via alkaline hydrolysis were subjected to pharmacological testing in vivo in order to evaluate their antiinflammatory activity.