Simona Rapposelli

Design, synthesis and pharmacological evaluation of novel tacrine-caffeic acid hybrids as multi-targeted compounds against Alzheimer's disease.

A novel series of tacrine-caffeic acid hybrids (5a-f) were designed and synthesized by combining caffeic acid (CA) with tacrine. The antioxidant study revealed that all the hybrids have much more antioxidant capacities compared to CA. Among these compounds, 5e showed the highest selectivity in inhibiting acetylcholinesterase (AChE) over butyrylcholinesterase (BuChE). Enzyme kinetic study had suggested that 5e binds to both catalytic (CAS) and peripheral anionic sites (PAS) of AChE. Moreover, compound 5e also inhibited self- or AChE-induced β-amyloid(1-40) aggregation, as well as had potent neuroprotective effects against H(2)O(2)- and glutamate- induced cell death with low toxicity in HT22 cells.

Arylthioamides as H2S Donors: l-Cysteine-Activated Releasing Properties and Vascular Effects in Vitro and in Vivo

A small library of arylthioamides 1-12 was easily synthesized, and their H2S-releasing properties were evaluated both in the absence or in the presence of an organic thiol such as l-cysteine. A number of arylthioamides (1-3 and 7) showed a slow and l-cysteine-dependent H2S-releasing mechanism, similar to that exhibited by the reference slow H2S-releasing agents, such as diallyl disulfide (DADS) and the phosphinodithioate derivative GYY 4137. Compound 1 strongly abolished the noradrenaline-induced vasoconstriction in isolated rat aortic rings and hyperpolarized the membranes of human vascular smooth muscle cells in a concentration-dependent fashion. Finally, a significant reduction of the systolic blood pressure of anesthetized normotensive rats was observed after its oral administration. Altogether these results highlighted the potential of arylthioamides 1-3 and 7 as H2S-donors for basic studies, and for the rational design/development of promising pharmacotherapeutic agents to treat cardiovascular diseases.

Discovery of novel N-substituted carbazoles as neuroprotective agents with potent anti-oxidative activity

Carbazole moiety is an important scaffold with a variety of biological applications, for example, anti-oxidative stress. Our previous synthesized carbazoles were screened for their neuroprotective properties against two individual oxidative stresses. Some of the new carbazole derivatives were observed with modest to good neuroprotective effects on neuronal cells HT22 against cell injury induced by glutamate or homocysteic acid (HCA). Substituents introduced to the carbazole ring system play crucial roles in their biological activities. In particular, a bulky group favors the neuroprotective activity of the compounds. One of the new compounds, 6, showed the best neuroprotective effects, which might result from its anti-oxidative activity with a GSH-independent mechanism. These findings might provide an alternative strategy for the development of novel carbazole derivatives for the treatment of CNS diseases such as Alzheimers disease.

Combined inhibition of AKT/mTOR and MDM2 enhances Glioblastoma Multiforme cell apoptosis and differentiation of cancer stem cells

The poor prognosis of Glioblastoma Multiforme (GBM) is due to a high resistance to conventional treatments and to the presence of a subpopulation of glioma stem cells (GSCs). Combination therapies targeting survival/self-renewal signals of GBM and GSCs are emerging as useful tools to improve GBM treatment. In this context, the hyperactivated AKT/mammalian target of the rapamycin (AKT/mTOR) and the inhibited wild-type p53 appear to be good candidates. Herein, the interaction between these pathways was investigated, using the novel AKT/mTOR inhibitor FC85 and ISA27, which re-activates p53 functionality by blocking its endogenous inhibitor murine double minute 2 homologue (MDM2). In GBM cells, FC85 efficiently inhibited AKT/mTOR signalling and reactivated p53 functionality, triggering cellular apoptosis. The combined therapy with ISA27 produced a synergic effect on the inhibition of cell viability and on the reactivation of p53 pathway. Most importantly, FC85 and ISA27 blocked proliferation and promoted the differentiation of GSCs. The simultaneous use of these compounds significantly enhanced GSC differentiation/apoptosis. These findings suggest that FC85 actively enhances the downstream p53 signalling and that a combination strategy aimed at inhibiting the AKT/mTOR pathway and re-activating p53 signalling is potentially effective in GBM and in GSCs.

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.

Synthesis of heteroaromatic analogues of (2-aryl-1-cyclopentenyl-1-alkylidene)-(arylmethyloxy)amine COX-2 inhibitors: effects on the inhibitory activity of the replacement of the cyclopentene central core with pyrazole, thiophene or isoxazole ring.

Several heteroaromatic analogues of (2-aryl-1-cyclopentenyl-1-alkylidene)-(arylmethyloxy)amine COX-2 inhibitors, in which the cyclopentene moiety was replaced by pyrazole, thiophene or isoxazole ring, were synthesized, in order to verify the influence of the different nature of the central core on the COX inhibitory properties of these kinds of molecules. Among the compounds tested, only the 3-(p-methylsulfonylphenyl) substituted thiophene derivatives 17 and 22, showed a certain COX-2 inhibitory activity, accompanied by an appreciable COX-2 versus COX-1 selectivity. Only one of the 1-(p-methylsulfonylphenyl)pyrazole compounds (16) displayed a modest inhibitory activity towards both type of isoenzymes, while the pyrazole 1-(p-aminosulfonylphenyl) substituted 12 proved to be significantly active only towards COX-1. All the isoxazole derivatives were inactive on both COX isoforms.

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).

Design, Synthesis, and Evaluation of Thyronamine Analogues as Novel Potent Mouse Trace Amine Associated Receptor 1 (mTAAR1) Agonists.

Trace amine associated receptor 1 (TAAR1) is a G protein coupled receptor (GPCR) expressed in brain and periphery activated by a wide spectrum of agonists that include, but are not limited to, trace amines (TAs), amphetamine-like psychostimulants, and endogenous thyronamines such as thyronamine (T0AM) and 3-iodothyronamine (T1AM). Such polypharmacology has made it challenging to understand the role and the biology of TAAR1. In an effort to understand the molecular basis of TAAR1 activation, we rationally designed and synthesized a small family of thyronamine derivatives. Among them, compounds 2 and 3 appeared to be a good mimic of the parent endogenous thyronamine, T0AM and T1AM, respectively, both in vitro and in vivo. Thus, these compounds offer suitable tools for studying the physiological roles of mouse TAAR1 and could represent the starting point for the development of more potent and selective TAAR1 ligands.

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.

P-gp Transporter and its Role in Neurodegenerative Diseases

This paper describes an overview of recent insights concerning some socially relevant neurodegenerative diseases such as Alzheimers (AD), Parkinsons (PD), Huntingtons (HD) and Creutzfeldt-Jakobs (CJD) diseases, amyotrophic lateral sclerosis (ALS) and epilepsy. For each pathological state, the direct and/or indirect involvement of P-glycoprotein (P-gp) efflux transport is underlined. On this basis, P-gp still represents an innovative target which can offer new tools for the development of more effective and preventive therapeutic strategies for neurodegenerative disorders. For each of them, therefore, a possible use of drugs affecting P-gp transport activity has been suggested.