Maria Digiacomo

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.

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.

Synthesis and pharmacological evaluation of multifunctional tacrine derivatives against several disease pathways of AD.

A novel series of tacrine derivatives were designed and synthesized by combining caffeic acid (CA), ferulic acid (FA) and lipoic acid (LA) with tacrine. The antioxidant study revealed that all the hybrids have much more antioxidant capacities compared to CA. Among these compounds, 1b possessed a good ability to inhibit the β-amyloid protein (Aβ) self-aggregation, sub-micromole acetylcholinesterase (AChE)/butyrylcholinesterase (BuChE) inhibitory, modest BACE1 inhibitory. Moreover, compound 1b also was a DPPH radical scavenger and copper chelatory as well as had potent neuroprotective effects against glutamate-induced cell death with low toxicity in HT22 cells. Our findings suggest that the compound 1b might be a promising lead multi-targeted ligand and worthy of further developing for the therapy of Alzheimers disease.

Anti-ischemic properties of a new spiro-cyclic benzopyran activator of the cardiac mito-KATP channel

Many activators of K(ATP) channels exhibit cardioprotective effects, mainly mediated by channels expressed on mitochondria (mito-K(ATP)). Previous results showed anti-ischemic effects of the spiro-cyclic derivative A, on isolated rat hearts. In this work this molecule was more extensively studied and diazoxide was used as reference mito-K(ATP) opener. The studies were performed on an in vivo rat model of myocardial infarct and on heart-derived H9c2 cells exposed to an anoxic environment. The mechanism of action was further investigated on isolated rat heart mitochondria. In the model of myocardial infarct compound A and diazoxide produced significant cardioprotective effects, antagonised by the selective mito-K(ATP) blocker 5-hydroxydecanoic acid (5-HD). Compound A, like diazoxide, produced modest and non-significant hypotensive responses, while the hyperglycaemic effects of diazoxide were not observed for the new compound. Protective effects of compound A and diazoxide were also recorded in H9c2 cells and again were inhibited by 5-HD. Compound A and diazoxide caused swelling of cardiac mitochondria, in agreement with the profile of mito-K(ATP) openers. Both compounds evoked concentration-dependent Ca2+-release from Ca2+-preloaded mitochondria, prevented mitochondrial Ca2+-uptake and caused mitochondrial membrane depolarisation. These effects were antagonised by ATP, the endogenous K(ATP) inhibitor. In conclusion, compound A exhibits a promising profile of an anti-ischemic agent, with a mechanism likely to be linked to the activation of mito-K(ATP) channels, and, because of its chemical characteristics such as structural rigidity and chirality due to the spiro-cyclic moiety, represents an interesting template for development of analogues further improved in activity and selectivity.

Spirocyclic Benzopyran-Based Derivatives as New Anti-ischemic Activators of Mitochondrial ATP-Sensitive Potassium Channel

Heart mitochondrial ATP-sensitive potassium channels (mito-K ATP channels) are deeply implicated in the self-defense mechanism of ischemic preconditioning. Therefore, exogenous molecules activating these channels are considered as a promising pharmacological tool to reduce the myocardial injury deriving from ischemia/reperfusion events. This paper reports the synthesis and pharmacological evaluation of original spiromorpholine- and spiromorpholone-benzopyran derivatives, with the aim to obtain selective activators of mito-K ATP channels. Some compounds of this series showed appreciable cardioprotective effects on rat isolated and perfused hearts, submitted to ischemia/reperfusion cycles. The selective mito-K ATP channel blocker 5-hydroxydecanoic acid antagonized the anti-ischemic activity, indicating a clear implication of this pharmacological target. Furthermore, these effects were not associated with significant hypotensive and vasorelaxing properties, which represent one of the main limiting factors for the clinical use of nonselective K ATP-openers against myocardial ischemia.

Design and synthesis of 2-oxindole based multi-targeted inhibitors of PDK1/Akt signaling pathway for the treatment of glioblastoma multiforme

Aggressive behavior and diffuse infiltrative growth are the main features of Glioblastoma multiforme (GBM), together with the high degree of resistance and recurrence. Evidence indicate that GBM-derived stem cells (GSCs), endowed with unlimited proliferative potential, play a critical role in tumor development and maintenance. Among the many signaling pathways involved in maintaining GSC stemness, tumorigenic potential, and anti-apoptotic properties, the PDK1/Akt pathway is a challenging target to develop new potential agents able to affect GBM resistance to chemotherapy. In an effort to find new PDK1/Akt inhibitors, we rationally designed and synthesized a small family of 2-oxindole derivatives. Among them, compound 3 inhibited PDK1 kinase and downstream effectors such as CHK1, GS3Kα and GS3Kβ, which contribute to GCS survival. Compound 3 appeared to be a good tool for studying the role of the PDK1/Akt pathway in GCS self-renewal and tumorigenicity, and might represent the starting point for the development of more potent and focused multi-target therapies for GBM.

Predictive models, based on classification algorithms, for compounds potentially active as mitochondrial ATP-sensitive potassium channel openers

Heart mitochondrial ATP-sensitive potassium channel (mito-K(ATP) channels) are deeply implicated in the self-defense mechanism of ischemic preconditioning. Therefore, exogenous molecules activating these channels are considered as a promising pharmacological tool to reduce the myocardial injury deriving from ischemia/reperfusion events. In our laboratory, a series of 4-spiro-substituted benzopyran derivatives were earlier synthesized and some of them exhibited anti-ischemic properties. In this study, the above compounds are exploited in order to develop QSAR models, based on classification approaches, capable of discriminating between the ones acting as cardioprotective agents and those that are unable to elicit such a property. Molecules belonging to the whole dataset were subjected to CODESSA and E-Dragon calculations in order to compute a large number of molecular descriptors enabling the construction of classification models. Based on the two program packages used, two different experiments were carried out, with the aim of identify batteries of models to be exploited for designing new cardioprotective agents from libraries of new chemical entities. Both model batteries satisfy the rigorous criteria adopted for the validation, either when tested on the training and test set, according to the most straightforward protocol, and when tested on an additional prediction set. They were proven to ensure successful applications in the field of cardioprotective agent design.

2-[(3-Methoxyphenylethyl)phenoxy]-Based ABCB1 Inhibitors : Effect of Different Basic Side-Chains on Their Biological Properties

Recently, 2-[(3-methoxyphenylethyl)phenoxy]-moiety has been selected for the design and synthesis of new small ABCB1 inhibitors. In the present paper, this moiety has been linked through a spacer of 2-5 carbon atoms to the nitrogen of three different basic nuclei such as: (i) N-4-arylpiperazine, (ii) N-4-methylpiperazine, and (iii) 6,7-dimethoxytetrahydroisoquinoline. The results demonstrated that all the selected basic nuclei were well tolerated and that, globally, the best inhibitory activity for each series was obtained when the spacer between the 2-[(3-methoxyphenylethyl)phenoxy] moiety and the basic nucleus consisted of a four-carbon chain. Among the synthesized compounds, N-4-methylpiperazine- 10c (IC(50) = 0.15 microM) and tetrahydroisoquinoline-derivatives 11c (IC(50) = 0.08 microM) with the spacer n = 4 for both series, displayed the best potency to inhibit ABCB1 activity. Moreover, for each compound, the ABCB1 interacting mechanism has been evaluated by three combined biological assays. N-4-methylpiperazine- (10a-d) and tetrahydroisoquinoline- (11a-d) derivatives were Cyclosporin A-like ABCB1 nontransported substrates.

NO-glibenclamide derivatives: Prototypes of a new class of nitric oxide-releasing anti-diabetic drugs

Endothelial dysfunction and consequent reduction of biosynthesis of endogenous nitric oxide (NO) play an important pathogenetic role in the cardiovascular complications associated with type II diabetes. In this work, the hybrid drugs 3a and 3b, nitrooxymethylbenzoate-derivatives of 1 (which is a hydroxylated active metabolite of glibenclamide 2), are reported. The pharmacodynamic characterization of 3b showed that its hypoglycaemic activity is enriched with additional NO-donor effects, conferring vasorelaxing and anti-platelet properties of potentially great usefulness for diabetes-related cardiovascular disorders.