Simone Bertini

Inhibitors of lactate dehydrogenase isoforms and their therapeutic potentials.

In many different species, lactate dehydrogenase (LDH) constitutes a major checkpoint of anaerobic glycolysis, by catalyzing the reduction of pyruvate into lactate. This enzyme has recently received a great deal of attention since it may constitute a valid therapeutic target for diseases so different as malaria and cancer. In fact, the isoform expressed by Plasmodium falciparum (pfLDH) is a key enzyme for energy generation of malarial parasites. These species mostly depend on anaerobic glycolysis for energy production, since they lack a citric acid cycle for ATP formation. Therefore, inhibitors of pfLDH would potentially cause mortality of P. falciparum and, to this purpose, several small organic molecules have been recently designed and developed with the aim of blocking this new potential antimalarial chemotherapeutic target. Moreover, most invasive tumour phenotypes show a metabolic switch (Warburg effect) from oxidative phosphorylation to an increased anaerobic glycolysis, by promoting an upregulation of the human isoform-5 of lactate dehydrogenase (hLDH-5 or LDH-A), which is normally present in muscles and in the liver. Hence, inhibition of hLDH-5 may constitute an efficient way to interfere with tumour growth and invasiveness. This review provides an overview of the LDH inhibitors that have been developed up to now, an analysis of their possible isoform-selectivity, and their therapeutic potentials.

N6-isopentenyladenosine arrests tumor cell proliferation by inhibiting farnesyl diphosphate synthase and protein prenylation

The physiological effects of a variety of N6‐substituted adenine and adenosine derivatives called cytokinins have been documented in plants, but information on their occurrence and function in other biological system is limited. Here we investigated the anti‐proliferative effect of N6‐isopentenyladenosine (i6A), an adenosine and isoprenoid derivative, in a thyroid cell system, FRTL‐5 wild‐type, and K‐ras transformed KiMol cells. Addition of i6A to FRTL‐5 cells caused a dose‐dependent arrest of the G0‐G1 cell phase transition associated with a reduction of cells in the S phase that was much more evident in KiMol cells. I6A arrested tumor cell proliferation by inhibiting farnesyl diphosphate synthase (FPPS) and protein prenylation. Indeed the addition of farnesol reversed these effects and i6A affected protein prenylation, in particular lamin B processing. I6A effect was not mediated by the adenosine receptor but was due to a direct modulation of FPPS enzyme activity as a result of its uptake inside the cells. I6A inhibited FPPS activity more efficaciously in KiMol cells than in normal FRTL‐5. Moreover, the i6A anti‐proliferative effect was evaluated in vivo in a nude mouse xenograft model, where KiMol cells were implanted subcutaneously. Mice treated with i6A showed a drastic reduction in tumor volume. Our findings indicate that this isoprenoid end product might be used for antineoplastic therapy, an application emulating that of the lovastatin and/or farnesyltransferase inhibitors.—Laezza, C., Notarnicola, M., Caruso, M. G., Messa, C., Macchia, M., Bertini, S., Minutolo, F., Portella, G., Fiorentino, L., Stingo, S., Bifulco, M. N6‐isopentenyladenosine arrests tumor cell proliferation by inhibiting farnesyl diphosphate synthase and protein prenylation. FASEB J. 20, 412–418 (2006)

THE PLASMA KINETICS AND TISSUE DISTRIBUTION OF ENROFLOXACIN AND ITS METABOLITE CIPROFLOXACIN IN THE MUSCOVY DUCK

Intorre, L., Mengozzi, G., Bertini, S., Bagliacca, M., Luchetti, E. and Soldani, G., 1997. The plasma kinetics and tissue distribution of enrofloxacin and its metabolite ciprofloxacin in the Muscovy duck. Veterinary Research Communications, 21 (2), 127-136

Structural Evolutions of Salicylaldoximes as Selective Agonists for Estrogen Receptor β

The bioisosteric replacement of the phenol ring, a signature functional group of most estrogen receptor (ER) ligands, with a hydrogen-bonded pseudocyclic ring, led to the development of a novel class of nonsteroidal ER-ligands based on a salicylaldoxime template. A series of structural modifications were applied to selected molecules belonging to the monoaryl-salicylaldoxime chemical class in an attempt to improve further their ERbeta-selective receptor affinity and agonist properties. Among several modifications, the best results were obtained by the simultaneous introduction of a meta-fluorine atom into the para-hydroxyphenyl substituent present in the 4-position of salicylaldoxime, together with the insertion of a chloro group in the 3-position of the central scaffold. The resulting compound showed the best affinity (K(i) = 7.1 nM) and selectivity for ERbeta over ERalpha. Moreover, in transcription assays, it proved to be a selective and potent ERbeta-full agonist with an EC(50) of 4.8 nM.

α-Naphthylaminopropan-2-ol Derivatives as BACE1 Inhibitors

Alzheimer’s disease (AD) causes progressive neurodegeneration; brain neurons of people affected by this pathology are characterized by the presence of extracellular senile plaques, mainly consisting of amyloid b (Ab) peptide aggregates, and intracellular neurofibrillary tangles caused by the aggregation of tau proteins, both of which are proposed to play a key role in the progression of AD. The formation of the Ab peptide from the amyloid precursor protein (APP) is catalyzed by BACE1 (b-secretase), a proteolytic enzyme belonging to the aspartyl protease family, widely recognized as a potential therapeutic target for the treatment of AD. Many known BACE1 inhibitors incorporate a hydroxyethylamine (HEA) transition state isostere moiety. Some of the most potent inhibitors are peptidomimetic structures or possess relatively high molecular weights, however, BACE1 is found inside the central nervous system (CNS) and, therefore, blood–brain barrier (BBB) permeation is an additional issue to be addressed, for example, by a reduction in molecular weight and in the overall polarity of the drug candidate. To identify new BACE1 inhibitors, a series of commercially available HEA-derived molecules was screened using a recently developed high-throughput screening (HTS) fluorescence assay. Compound 1, a dibromo-substituted carbazole containing an a-naphthylaminopropan-2-ol portion, was identified by the HTS assay as a good inhibitor of BACE1 with an IC50 value of 1.1 mm. A series of compound 1 analogues was designed and synthesized, keeping the aminoalcohol moiety intact and varying the heterocyclic terminal group (Figure 1). The choice of the heterocyclic moiety was directed by three factors; i) reduction of the molecular weight of 1, ii) structural resemblance to 1, and iii) availability of synthetic precursors. The carbazoleand indole-derived heterocycles were selected to replace the 3,6-dibromocarbazole moiety in compound 1. The closely related carbazole derivatives synthesized include unsubstituted carbazole (2a), 3,6-dichlorocarbazole (2b), and 1,2,3,4-tetrahydrocarbazole (2c), as well as the substituted indoles (2d–f) (Table 1).

Oxime-based inhibitors of glucose transporter 1 displaying antiproliferative effects in cancer cells.

An analysis of the main pharmacophoric features present in the still limited number of inhibitors of glucose transporter GLUT1 led to the identification of new oxime-based inhibitors, which proved to be able to efficiently hinder glucose uptake and cell growth in H1299 lung cancer cells. The most important interactions of a representative inhibitor were indicated by a novel computational model of GLUT1, which was purposely developed to explain these results and to provide useful indications for the design and the development of new and more efficient GLUT1 inhibitors.

Selective and potent agonists for estrogen receptor beta derived from molecular refinements of salicylaldoximes

In a continuing effort to improve the subtype selectivity and agonist potency of estrogen receptor β (ERβ) ligands, we have designed and developed a thus far unexplored structural series obtained by molecular refinements of monoaryl-substituted salicylaldoximes (Salaldox B). The most interesting compounds in this series (2c, d) show remarkably high ERβ-binding affinities, with Ki values reaching the sub-nanomolar range (Ki=0.38 nM for 2c and 0.57 nM for 2d), and have very high levels of ERβ-subtype selectivity. Both compounds show a potent full agonist character on ERβ (EC50=0.23 nM for 2c and 1.3 nM for 2d). Furthermore, 2d shows a remarkable functional subtype selectivity, with a β/α transcription potency ratio 50-fold higher than that of estradiol.

Synthesis, binding affinity, and transcriptional activity of hydroxy- and methoxy-Substituted 3,4-Diarylsalicylaldoximes on estrogen receptors α and β

Abstract An effective, unprecedented replacement of the prototypical phenolic ‘A-ring’ of estrogens with an oxime and a hydroxy-moiety of the salicylaldoxime derivative 3,4-diphenyl-substituted ( 1a ) opened the way to study structure–activity relationships of a new class of estrogen receptor (ER)-ligands. Herein, we present a study of the ER binding properties and transcriptional activities of analogues of 3,4-diphenylsalicylaldoxime ( 1a ). The introduction of p -OH and p -OMe groups on the phenyl substituents of 1a , as in compounds 1b – g , results in unique structure–activity profiles. The preparation of the hetero-disubstituted compounds ( 1b – e ) was accomplished by a sequential introduction of different 3- and 4-aryl groups, obtained by exploiting the different reactivity of the bromine versus chlorine substituents on the precursor, 2-bromo-3-chloronitrobenzene ( 5 ), in the palladium-catalyzed cross-coupling reactions. The results of the biological tests show that the introduction of one hydroxy-group on the 3-phenyl substituent of the lead compound 1a improved the binding affinity on ERβ ( 1c ), whereas the introduction of the same group on the 4-phenyl substituent of 1a gave a compound ( 1e ) with better affinity properties on ERα. The introduction of two hydroxyl groups in the para -position of both phenyl substituents of 1a , as in 1g , lowered the binding on both receptor subtypes. In transcription assays, the ERα agonist character of this class of ligands is enhanced by the presence of a p -hydroxy or p -methoxy in the ‘distal’ phenyl ring, whereas substitution on the other phenyl ring does not substantially modify the partial agonist character of 1a . Thus, results from the binding and transcription assays illustrate that this class of ER ligands has a distinct structure–activity profile on the two ER subtypes, being potent nearly full agonists on ERα and weak, partial antagonists on ERβ.

Regulation of gastric acid secretion by histamine H3 receptors in the dog: an investigation into the site of action

The involvement of histamine H3 receptors in the regulation of gastric acid secretion was investigated in the conscious dog with gastric fistula, by the use of the selective agonist (R)α-methylhistamine and the selective antagonist thioperamide. (R)α-methylhistamine (0.3–1.2 μmol/kg/h) induced a dose-related inhibition of the acid secretion induced by pentagastrin and by bombesin, maximum inhibition not exceeding 60–65%. The inhibitory effect of the H3 agonist (0.6 μmol/kg/h) was inhibitited by thioperamide (0.1 μmol/kg/h), suggesting that the effect was entirely mediated by H3 receptors. Thioperamide was also able to enhance the acid response to submaximal doses of pentagastrin and bombesin. The acid secretion induced by histamine was not modified by (R)a-methylhistamine (0.3–1.2 μmol/kg/h) but it was significantly enhanced by thioperamide (0.1 μmol/kg/h). Neither (R)α-methylhistamine nor thioperamide significantly modified the increase in plasma gastrin levels induced by bombesin. In conclusion these data demonstrate that histamine H3 receptors may represent an effective mechanism for the negative control of stimulated gastric acid secretion in the dog; however, since the inhibition was mainly evident against stimuli which involve the release of histamine, a location of H3 receptors in paracrine cells of the gastric mucosa rather than in gastrin producing cells or parietal cells seems more likely.

New quinolone- and 1,8-naphthyridine-3-carboxamides as selective CB2 receptor agonists with anticancer and immuno-modulatory activity.

Several recent studies suggest that selective CB2 receptor agonists may represent a valid pharmacological approach in the treatment of various diseases due to the absence of relevant psychoactive side effect. In this study, we synthesized and tested a series of new quinoline-2(1H)-one- and 4-hydroxy-2-oxo-1,2-dihydro-1,8-naphthyridine derivatives characterized by a 4-methylcyclohexylamido substituent in position 3 of the heterocyclic nucleus with high CB2 receptor affinity and selectivity. Two compounds showing the best binding and selectivity profile behaved as a full agonist and a partial agonist at the CB2 receptor and induced a concentration-dependent decrease of cell viability on LNCaP, a prostatic cancer cell line expressing CB2 receptor. Moreover considering that the CB2 receptor is mainly expressed in cells and organs of the immune system, the same compounds were studied for their potential immune-modulatory and anti-inflammatory effects in activated lymphocytes isolated from healthy controls and multiple sclerosis (MS) patients.