Synthesis, biological evaluation and quantitative structure-active relationships of 1,3-thiazolidin-4-one derivatives. A promising chemical scaffold endowed with high antifungal potency and low cytotoxicity

With reference to recent studies reporting on the various biological properties of the thiazolidinone scaffold, we synthesized more than a hundred compounds characterized by a 1,3-thiazolidin-4-one nucleus derivatised at the C2 with a hydrazine bridge linked to (cyclo)aliphatic or hetero(aryl) moieties, and their N-benzylated derivatives. These molecules were assayed as potential anti-Candida agents and they were shown to possess comparable, and in some cases higher biological activity than well-established topical and systemic antimycotic drugs (i.e. clotrimazole, fluconazole, ketoconazole, miconazole, tioconazole, amphotericin B). Compounds endowed with the lowest MICs underwent further testing in order to assess their cytotoxic effect (CC₅₀) on Hep2 cells, which demonstrated their relative safety. Finally, QSAR and 3-D QSAR models were used to predict putative chemical modifications of the 1,3-thiazolidin-4-one scaffold in order to design new and potential more active compounds against Candida spp.

Synthesis and biological evaluation of anti-Toxoplasma gondii activity of a novel scaffold of thiazolidinone derivatives

We designed and synthesised novel N-substituted 1,3-thiazolidin-4-one derivatives for the evaluation of their anti-Toxoplasma gondii efficacy. This scaffold was functionalised both at the N1-hydrazine portion with three structurally different moieties and at the lactam nitrogen with substituted benzyl groups selected on the basis of our previous structure-activity relationships studies. Using three different assay methods, the compounds were assessed in vitro to determine both the levels of efficacy against the tachyzoites of T. gondii (IC₅₀ = 5-148 μM), as well as any evidence of cytotoxicity towards human host cells (TD₅₀ = 68 to ≥320 μM). Results revealed that ferrocene-based thiazolidinones can possess potent anti-tachyzoite activity (TI =2-64).

Dilated intercellular space diameter as marker of reflux-related mucosal injury in children with chronic cough and gastro-oesophageal reflux disease

BACKGROUND

The diagnostic corroboration of the relationship between gastro-oesophageal reflux disease (GERD) and chronic cough remains challenging.

AIMS

To compare oesophageal mucosal intercellular space diameter (ISD) in children with GERD, children with gastro-oesophageal reflux (GER)-related cough (GrC) and a control group, and to explore the relationship between baseline impedance levels and dilated ISD in children with GER-related cough.

METHODS

Forty children with GERD, 15 children with GrC and 12 controls prospectively underwent oesophagogastroduodenoscopy (EGD) with oesophageal biopsies taken 2-3 cm above squamocolumnar junction. ISD were quantified using transmission electron microscopy. Impedance-pH monitoring with evaluation of baseline impedance in the most distal impedance channel was performed in both patient groups.

RESULTS

A significant difference in mean ISD values was found between GrC patients (0.9 ± 0.2 μm) and controls (0.5 ± 0.2 μm, P < 0.001), whereas there was no difference between GrC and GERD group (1 ± 0.3 μm, NS). No difference was found in the mean ISD between GrC children with or without pathological oesophageal acid exposure time (1 ± 0.3 vs. 0.9 ± 0.2 μm), and there was no correlation between ISD and any reflux parameter. Finally, there was no correlation between ISD and distal baseline impedance values (r:-0.35; NS).

CONCLUSIONS

In children with reflux-related cough, dilated intercellular space diameter appears to be an objective and useful marker of oesophageal mucosal injury regardless of acid exposure, and its evaluation should be considered for those patients where the diagnosis is uncertain. In children with reflux-related cough, baseline impedance levels have no role in identifying reflux-induced oesophageal mucosal ultrastructural changes.

Relationship between baseline impedance levels and esophageal mucosal integrity in children with erosive and non-erosive reflux disease

BACKGROUND

Baseline impedance measurement has been reported to be related to esophageal acid exposure and hypothesized to be a marker of microscopic changes of the esophageal mucosa. Aims of the study were to establish whether any relationship existed between the magnitude of intercellular space diameter (ISD) of esophageal mucosa and baseline impedance levels in children with gastro-esophageal reflux disease (GERD), and to compare baseline impedance levels between children with non erosive (NERD) and erosive (ERD) reflux disease.

METHODS

Fifteen children (median age: 11.2 years) with NERD, and 11 with ERD (median age: 9.6 years) were prospectively studied. All patients underwent upper endoscopy. Biopsies were taken 2-3cm above the Z-line, and ISD was measured using transmission electron microscopy. All patients underwent impedance pH-monitoring, and baseline impedance levels were assessed in the most distal impedance channel.

KEY RESULTS

Mean (±SD) ISD did not differ between NERD (1.0±0.3μm) and ERD (1.1 ± 0.3 μm, ns). Considering all patients together, no correlation was found between distal baseline impedance and ISD (r: -0.15; ns). Conversely, negative correlations were found between distal baseline impedance and acid exposure time (r: -0.76; P<0.001), long-lasting reflux episodes (r: -0.78; P<0.001), acid reflux episodes (r: -0.62; P<0.001), and acid clearance time (r: -0.79; P<0.001). Distal baseline impedance was significantly lower in ERD [1455 (947-2338) Ω] than in NERD children [3065 (2253-3771) Ω; P<0.01].

CONCLUSIONS & INFERENCES

  In children with GERD baseline impedance levels are not useful in predicting reflux-induced ultrastructural changes in the esophageal mucosa, despite their ability to discriminate between NERD and ERD.

Synthesis, anti-Candida activity, and cytotoxicity of new (4-(4-iodophenyl)thiazol-2-yl)hydrazine derivatives

Novel (4-(4-iodophenyl)-thiazol-2-yl)hydrazine derivatives were assayed for their in vitro anti-Candida activity, compared to topical and systemic antifungal drugs, against twenty-seven clinical isolates. The presence of aliphatic chains or specific heteroaromatic rings on hydrazone moiety at position C2 and a 4-iodophenyl at C4 of the thiazole ring gave a promising inhibitory activity especially against Candida albicans and Candida krusei. The most active compounds have been also evaluated for their cytotoxicity and in association with clotrimazole for anti-Candida activity.

CPTH6, a thiazole derivative, induces histone hypoacetylation and apoptosis in human leukemia cells

PURPOSE

We previously identified novel thiazole derivatives able to reduce histone acetylation and histone acetyltransferase (HAT) activity in yeast. Among these compounds, 3-methylcyclopentylidene-[4-(4'-chlorophenyl)thiazol-2-yl]hydrazone (CPTH6) has been selected and used throughout this study.

EXPERIMENTAL DESIGN

The effect of CPTH6 on histone acetylation, cell viability and differentiation, cell-cycle distribution, and apoptosis in a panel of acute myeloid leukemia and solid tumor cell lines has been evaluated.

RESULTS

Here, we showed that CPTH6 leads to an inhibition of Gcn5 and pCAF HAT activity. Moreover, it inhibits H3/H4 histones and α-tubulin acetylation of a panel of leukemia cell lines. Concentration- and time-dependent inhibition of cell viability, paralleled by accumulation of cells in the G(0)/G(1) phase and depletion from the S/G(2)M phases, was observed. The role of mitochondrial pathway on CPTH6-induced apoptosis was shown, being a decrease of mitochondrial membrane potential and the release of cytochrome c, from mitochondria to cytosol, induced by CPTH6. Also the involvement of Bcl-2 and Bcl-xL on CPTH6-induced apoptosis was found after overexpression of the two proteins in leukemia cells. Solid tumor cell lines from several origins were shown to be differently sensitive to CPTH6 treatment in terms of cell viability, and a correlation between the inhibitory efficacy on H3/H4 histones acetylation and cytotoxicity was found. Differentiating effect on leukemia and neuroblastoma cell lines was also induced by CPTH6.

CONCLUSIONS

These results make CPTH6 a suitable tool for discovery of molecular targets of HAT and, potentially, for the development of new anticancer therapies, which warrants further investigations.

Synthesis and evaluation of 4-acyl-2-thiazolylhydrazone derivatives for anti-Toxoplasma efficacy in vitro

A new series of 4-acyl-2-thiazolylhydrazone derivatives was synthesized and screened for its in vitro activity against Toxoplasma gondii. We evaluated parasite growth inhibition and cytotoxicity, inhibition of replication, and inhibition of parasite invasion of host cells. The biological results indicated that some substances had an antiproliferative effect against intracellular T. gondii tachyzoites cultivated in vitro.

Synthesis, molecular modeling, and selective inhibitory activity against human monoamine oxidases of 3-carboxamido-7-substituted coumarins

A large series of 3-carboxamido-7-substituted coumarins have been synthesized and tested in vitro for their human monoamine oxidase A and B (hMAO-A and hMAO-B) inhibitory activity. Taking into account all the relevant structural information on MAOs reported in the literature, we made some changes in the coumarin nucleus and examined with particular attention the effect on activity and selectivity of substituting at position 3 with N-aryl or N-alkyl carboxamide and at position 7 with a benzyloxy or a 4'-F-benzyloxy group. Some of the assayed compounds proved to be potent, selective inhibitors of hMAO-B with IC(50) values in the micromolar range. To better understand the enzyme-inhibitor interaction and to explain the selectivity of the most active compounds toward hMAOs, molecular modeling studies were carried out on new, high resolution, hMAO-A and hMAO-B crystallographic structures.

A novel histone acetyltransferase inhibitor modulating Gcn5 network: cyclopentylidene-[4-(4'-chlorophenyl)thiazol-2-yl)hydrazone

Acetylation is a key modulator of genome accessibility through decondensation of the chromatin structure. The balance between acetylation and opposite deacetylation is, in fact, a prerequisite for several cell functions and differentiation. To find modulators of the histone acetyltransferase Gcn5p, we performed a phenotypic screening on a set of newly synthesized molecules derived from thiazole in budding yeast Saccharomyces cerevisiae. We selected compounds that induce growth inhibition in yeast strains deleted in genes encoding known histone acetyltransferases. A novel molecule CPTH2, cyclopentylidene-[4-(4'-chlorophenyl)thiazol-2-yl)hydrazone, was selected based on its inhibitory effect on the growth of a gcn5Delta strain. We demonstrated a specific chemical-genetic interaction between CPTH2 and HAT Gcn5p, indicating that CPTH2 inhibits the Gcn5p dependent functional network. CPTH2 inhibited an in vitro HAT reaction, which is reverted by increasing concentration of histone H3. In vivo, it decreased acetylation of bulk histone H3 at the specific H3-AcK14 site. On the whole, our results demonstrate that CPTH2 is a novel HAT inhibitor modulating Gcn5p network in vitro and in vivo.

Reflux oesophagitis in children; the role of endoscopy. A multicentric Italian survey

BACKGROUND

The decision whether to perform endoscopy in children with suspected reflux oesophagitis is not a straightforward one. Few symptoms are specific for oesophagitis and the diagnosis is not always correlated even to visual findings on endoscopy.

AIM

The aim of this study was to define the role of endoscopy and especially of histology in the diagnosis of reflux oesophagitis and to examine the correlations between symptoms, endoscopic findings and histology in children with suspected gastroesophageal reflux disease.

PATIENTS AND METHODS

One hundred and thirty-six patients with a clinical diagnosis of reflux oesophagitis, aged 1-18 years (mean 8.43; standard deviation +/-4.4), were enrolled from 12 Italian Paediatrics Gastroenterology Centres; symptom score, endoscopic and histologic oesophagitis scores were observed before and after therapy with proton pump inhibitors.

RESULTS

Before therapy, a high correlation between the prevailing symptom score and endoscopic score was demonstrated, but not with histologic score: there was a significant tendency for histologic grade to exceed visual findings. After therapy, endoscopic score and histologic score were significantly improved.

CONCLUSIONS

Oesophageal biopsies increase the diagnostic accuracy of upper endoscopy. Histologic grading is often much more important than the endoscopic appearance, so that endoscopic oesophageal biopsies are very important aids in the diagnosis of oesophagitis. Appropriate clinical evaluation of symptoms must occur before endoscopic examination.

A novel class of selective anti-Helicobacter pylori agents 2-oxo-2H-chromene-3-carboxamide derivatives

A novel class of selective anti-Helicobacter pylori agents, 2-oxo-2H-chromene-3-carboxamide derivatives, were prepared and evaluated for their anti-bacterial activity. All synthesized compounds showed little or no activity against different species of Gram-positive and Gram-negative bacteria and against various strains of pathogenic fungi. Some of them exhibited a potent and specific inhibitory effect on the growth of H. pylori, including metronidazole-resistant strains, in the 0.0039-16 microg/mL MIC range. A cytotoxic screening by the Trypan blue dye exclusion assay was also carried out on the most active compounds as anti-H. pylori agents. Among the derivatives examined for their cytotoxic potential, a number of them induced low cytotoxic effects.

Synthesis and in vitro activity of 2-thiazolylhydrazone derivatives compared with the activity of clotrimazole against clinical isolates of Candida spp

In this paper, we report on the synthesis of a novel series of 2-thiazolylhydrazone derivatives and the influence of the substituents on the thiazole ring on antifungal activity. All synthesized compounds were screened for their in vitro activities against 22 clinical isolates of Candida spp., representing six different species, compared to clotrimazole as a reference compound. Some of the tested compounds were found to possess significant antifungal activity when compared to clotrimazole, in particular compound 14 which exhibited higher potency against most of the Candida spp. considered. The compounds that were most active as anti-Candida agents were also submitted to cytotoxic screening by the Trypan Blue dye exclusion assay and in general they were shown to induce low cytotoxic effects.

Synthesis and in vitro selective anti-Helicobacter pylori activity of N-substituted-2-oxo-2H-1-benzopyran-3-carboxamides

In order to develop new anti-Helicobacter pylori agents, five new and three already known N-substituted-2-oxo-2H-1-benzopyran-3-carboxamides (coumarin-3-carboxamides) were prepared and evaluated for their antibacterial activity. All synthesized compounds showed little or no activity against different species of Gram-positive and Gram-negative bacteria of clinical relevance and against various strains of pathogenic fungi. Among the prepared compounds those with a 4-acyl-phenyl group showed the best activity against H. pylori metronidazole resistant strains in the 0.25-1 microg/ml MIC range, indicating the presence of an acyl function as an important feature for activity.

Synthesis and in vitro selective anti-Helicobacter pylori activity of pyrazoline derivatives

In order to develop new anti-Helicobacter pylori agents, a series of N1-substituted 3,5-diphenyl pyrazolines P1-P13 was prepared and evaluated for their antibacterial activity. All synthesized compounds showed little or no activity against different species of Gram-positive and Gram-negative bacteria of clinical relevance and against various strains of pathogenic fungi. The same derivatives exhibited a significant degree of activity against a range of H. pylori strains, including those resistant to the reference compound metronidazole. Among the prepared compounds those with an N1-acetyl group and a 4-methoxy substituent in the 5-phenyl ring showed the best activity against H. pylori metronidazole resistant strains in the 1-4 microg/mL MIC range.

Inhibition of amine oxidases activity by 1-acetyl-3,5-diphenyl-4,5-dihydro-(1H)-pyrazole derivatives

A novel series of 1-acetyl-3,5-diphenyl-4,5-dihydro-(1H)-pyrazole derivatives have been synthesised and investigated for the ability to inhibit selectively monoamine oxidases, swine kidney oxidase, and bovine serum amine oxidase. The newly synthesised compounds 1-6 proved to be reversible and non-competitive inhibitors of all types of the assayed amine oxidases. Compounds inhibit monoamine oxidases potently, displaying low I(50) values of particular interest. In particular 1-acetyl-3-(2,4-dihydroxyphenyl)-5-(3-methylphenyl)-4,5-dihydro-(1H)-pyrazole 6 showed to be a potent monoamine oxidase inhibitor with a K(i) of about 10(-8)M. Further insights in the theoretical evaluation of the possible interactions between the compounds and monoamine oxidase B have been developed through a computational approach.

[Digestive endoscopy in neonates. Personal experience]

Gastrointestinal (GI) endoscopy is actually considered an essential diagnostic and therapeutic technique both in pediatrician and in newborn infants. At the moment upper GI endoscopy in neonatal age allows to explore the esophagus, stomach and duodenum; instead lower GI endoscopy easily reaches sigmoid-colon junction. The exploration of other distal parts of bowel is more difficult and with more risks. Therefore it has to be make only if it is necessary. In the newborn this exam should be so fast not to require premedication. In our study, we considered every neonatal patient who underwent GI endoscopy at the "Digestive Endoscopy and Gastroenterology Service of Pediatric Clinic-University of Parma" (from September 1983 to June 2000). We considered two groups of patients: first group: early neonatal age (0-14 days) second group: late neonatal age (15-28 days). We made 127 endoscopies: 112 of these were upper GI. The most frequent symptoms that babies showed and indicated upper GI endoscopy were reflux and/or vomiting (86%). Upper operative GI endoscopies included also 7 esophageal dilatations. The lower GI endoscopies were 15 and in all the cases the indication was intestinal bleeding. We conclude that the GI endoscopy in the neonates shows a diagnostic sensibility and specificity really high and for sure better than the radiology for mucosal lesions. Also GI endoscopy can be not only a very precious diagnostic instrument but also therapeutic in neonatal disease. Considering the age of the little patients, it is very important that only endoscopists with large experience use this technique.

Efficacy of Hypericum and Calendula oils in the epithelial reconstruction of surgical wounds in childbirth with caesarean section

Following studies on the properties of spontaneous plants in Sardinia we have evaluated the tissue regenerating action of a mixture of oily extracts of Hypericum perforatum and Calendula arvensis on surgical wounds from childbirth with caesarean section.

Visual field constriction in children with epilepsy on vigabatrin treatment

Vigabatrin is considered the drug of choice for infantile spasms and simple and complex partial epilepsy in childhood. Its mechanism of action relies on the irreversible inhibition of gamma-aminobutyric acid (GABA) transaminase. Since June 1997 several articles have been published reporting visual field constriction in adult patients on vigabatrin therapy. Recently, 7 pediatric patients, 1 on vigabatrin monotherapy and 6 on add-on therapy with visual field constriction have been described. We have observed 30 pediatric patients with epilepsy (14 boys and 16 girls), ages ranging from 4 to 20 years (mean: 11 years and 2 months) treated with vigabatrin for infantile spasms, simple and complex partial epilepsy, who had never complained of ophthalmologic disturbances. Twenty-one patients underwent complete routine ophthalmologic examination (fundus oculi, visual acuity, intraocular pressure, and visual field tests); 9 children (<6 years old) underwent only fundus examination, because collaboration was lacking. We report on 4 children showing constriction of visual field, prevailing in nasal hemifield. In 1 child, visual abnormalities were stable even 10 months after vigabatrin discontinuation, while in another a greater improvement was observed 5 months after discontinuation. The possible mechanisms have been discussed and the cone dysfunction, connected with GABA augmentation in the outer retina, has been outlined. We suggest a possible protocol to control visual abnormalities in epileptic children.

Synthesis and preliminary biological evaluation of 4,6-disubstituted 3-cyanopyridin-2(1H)-ones, a new class of calcium entry blockers

The preparation of 3-cyano-4,6-diaryl-pyridin-2(1H)-ones 4a-h, calcium entry blockers related to diltiazem, is described starting from 1,3-diaryl-2-propen-1-ones 5. On preliminary pharmacological tests all compounds are active and some of them show calcium antagonistic activity superior or comparable to diltiazem.

Inhibitory effect of 1,3,5-triphenyl-4,5-dihydro-(1H)-pyrazole derivatives on activity of amine oxidases

A new series of 1,3,5-triphenyl-4,5-dihydro-(1H)-pyrazole derivatives was synthesized to ascertain the contribution of substituted phenyl rings present on the 4,5-dihydro-(1H)-pyrazole nucleus to the monoamine oxidases inhibition and bovine serum amine oxidase inhibition. All compounds were tested on bovine brain mitochondria preparation containing flavin-monoamine oxidases and on purified bovine serum amine oxidases, taken as a model of trihydroxyphenylalanine quinone-copper-containing amine oxidases. The 1,3,5-triphenyl-4,5-dihydro-(1H)-pyrazole derivatives showed a good inhibitory activity and belonged to the third generation of monoamine oxidase inhibitors and bovine serum amine oxidase inhibitors which have the advantage of acting through a reversible mode. Furthermore, their activity showed a good degree of selectivity towards the bovine serum amine oxidase inhibition dependent on the substituents present on the phenyl ring at position 5 of the 4,5-dihydro-(1H)-pyrazole.

Synthesis and beta-adrenoreceptor blocking activity of [[3-(alkylamine)-2-hydroxypropyl]oximino]pyridines and O[3-(alkylamine)-2-hydroxypropyl]methylpyridine ketone oximes derivatives

[[3-(alkylamine)-2-hydroxypropyl]-2-oximino]pyridines and O-[3-(alkylamine)-2-hydroxypropyl]methylpyridine ketone oximes 5a-o were synthesized by a solid-liquid phase-transfer reaction, and their beta-adrenoreceptor blocking activity was evaluated in vitro and in vivo. The replacement of the aryl linked to the oximic carbon of the (methylenaminoxy)methyl moiety with the bioisoster pyridine ring produced a decrease of the beta-adrenergic blocking activity. The polarization of the oximic group, derived from the electron-withdrawing action of the nitrogen atom, is more evident for the 2-oxyminopyridine derivative 5d. But also conformational parameters may play an important role in the variation of activity of the compounds 5d, 5l and 5n. The replacement of the hydrogen linked to the oximic carbon with a methyl group increased the activity of the compounds 5a, 5i, 5m and 5o. The methyl could allow a delocalization of the partial positive charge present on the oximic carbon, but also its lipophilicity contributed to the increment of binding to the receptor site. None of the compounds showed high beta 1 or beta 2 selectivity in vitro. The (R) and (S) isomers of the compound 5a were synthesized and obtained with enantiomeric ratio 7:3 and 6:4, respectively. The binding tests and the pharmacological in vivo results confirmed the in vitro data.