Design, synthesis, biological evaluation and structural characterization of novel GEBR library PDE4D inhibitors.

Memory and cognitive functions depend on the cerebral levels of cyclic adenosine monophosphate (cAMP), which are regulated by the phosphodiesterase 4 (PDE4) family of enzymes. Selected rolipram-related PDE4 inhibitors, members of the GEBR library, have been shown to increase hippocampal cAMP levels, providing pro-cognitive benefits with a safe pharmacological profile. In a recent SAR investigation involving a subset of GEBR library compounds, we have demonstrated that, depending on length and flexibility, ligands can either adopt a twisted, an extended or a protruding conformation, the latter allowing the ligand to form stabilizing contacts with the regulatory domain of the enzyme. Here, based on those findings, we describe further chemical modifications of the protruding subset of GEBR library inhibitors and their effects on ligand conformation and potency. In particular, we demonstrate that the insertion of a methyl group in the flexible linker region connecting the catechol portion and the basic end of the molecules enhances the ability of the ligand to interact with both the catalytic and the regulatory domains of the enzyme.

New Hybrid Pyrazole and Imidazopyrazole Antinflammatory Agents Able to Reduce ROS Production in Different Biological Targets.

Several anti-inflammatory agents based on pyrazole and imidazopyrazole scaffolds and a large library of substituted catechol PDE4D inhibitors were reported by us in the recent past. To obtain new molecules potentially able to act on different targets involved in inflammation onset we designed and synthesized a series of hybrid compounds by linking pyrazole and imidazo-pyrazole scaffolds to differently decorated catechol moieties through an acylhydrazone chain. Some compounds showed antioxidant activity, inhibiting reactive oxygen species (ROS) elevation in neutrophils, and a good inhibition of phosphodiesterases type 4D and, particularly, type 4B, the isoform most involved in inflammation. In addition, most compounds inhibited ROS production also in platelets, confirming their ability to exert an antiinflammatory response by two independent mechanism. Structure-activity relationship (SAR) analyses evidenced that both heterocyclic scaffolds (pyrazole and imidazopyrazole) and the substituted catechol moiety were determinant for the pharmacodynamic properties, even if hybrid molecules bearing to the pyrazole series were more active than the imidazopyrazole ones. In addition, the pivotal role of the catechol substituents has been analyzed. In conclusion the hybridization approach gave a new serie of multitarget antiinflammatory compounds, characterized by a strong antioxidant activity in different biological targets.

Autologous Platelet Rich Plasma (PRP) in the treatment of elbow epicondylitis and plantar fasciitis: medium to long term clinical outcome.

BACKGROUND AND AIM: Platelet-Rich-Plasma (PRP) is a popular biological therapy especially used to regenerate different musculoskeletal tissues by releasing growth-factors and cytokines promoting cell proliferation, chemotaxis, differentiation, and angiogenesis. The aim was to evaluate the clinical effectiveness and safety of PRP for Lateral-Epicondylitis (LE) of the elbow and Plantar-Fasciitis (PF). METHODS: A retrospective study was conducted including patients treated with a single topic autologous-PRP-injection between 1-1-2009 and 7-18-2019 for LE or PF at our institution; patients operated for the same problem, patients refusing the study or not traceable were excluded. Patients were assessed with VAS for pain and clinical scales. RESULTS: 33 patients were treated with PRP and 13 (8F, 5M) included: 4LE and 9PF for a total of 16 cases. The average pain level was 0.61±0.63: 1±1.41 for LE and 0,44±0 for PF. No significant side effect was reported. 4 PRP-treatments failed: 2LE and 2PF. OES and PRTEE gave excellent results for elbow. Average foot scores were AOFAS 98.2±5 and FADI 91.3±1. Patients were stratified and compared according to plantar arch conformation, follow-up length, healing time, time from diagnosis to PRP-treatment, therapies before PRP (physiotherapy, steroid infiltration or shock-waves), risk factors (standing work, sport, age, sex). CONCLUSIONS: As in other studies, our results do not allow to draw sufficiently valid conclusions regarding the effectiveness and safety of PRP in the treatment of LE and PF: in particular the statistical significance is limited by the small sample size. PRP can be chosen as a non-first-line treatment for LE and PF.

New insights into selective PDE4D inhibitors: 3-(Cyclopentyloxy)-4-methoxybenzaldehyde O-(2-(2,6-dimethylmorpholino)-2-oxoethyl) oxime (GEBR-7b) structural development and promising activities to restore memory impairment.

Phosphodiesterase type 4D (PDE4D) has been indicated as a promising target for treating neurodegenerative pathologies such as Alzheimer's Disease (AD). By preventing cAMP hydrolysis, PDE4 inhibitors (PDE4Is) increase the cAMP response element-binding protein (CREB) phosphorylation, synaptic plasticity and long-term memory formation. Pharmacological and behavioral studies on our hit GEBR-7b demonstrated that selective PDE4DIs could improve memory without causing emesis and sedation. The hit development led to new molecule series, herein reported, characterized by a catechol structure bonded to five member heterocycles. Molecular modeling studies highlighted the pivotal role of a polar alkyl chain in conferring selective enzyme interaction. Compound 8a showed PDE4D3 selective inhibition and was able to increase intracellular cAMP levels in neuronal cells, as well as in the hippocampus of freely moving rats. Furthermore, 8a was able to readily cross the blood-brain barrier and enhanced memory performance in mice without causing any emetic-like behavior. These data support the view that PDE4D is an adequate molecular target to restore memory deficits in different neuropathologies, including AD, and also indicate compound 8a as a promising candidate for further preclinical development.

Synthesis, biological activities and pharmacokinetic properties of new fluorinated derivatives of selective PDE4D inhibitors.

A new series of selective PDE4D inhibitors has been designed and synthesized by replacing 3-methoxy group with 3-difluoromethoxy isoster moiety in our previously reported cathecolic structures. All compounds showed a good PDE4D3 inhibitory activity, most of them being inactive toward other PDE4 isoforms (PDE4A4, PDE4B2 and PDE4C2). Compound 3b, chosen among the synthesized compounds as the most promising in terms of inhibitory activity, selectivity and safety, showed an improved pharmacokinetic profile compared to its non fluorinated analogue. Spontaneous locomotor activity, assessed in an open field apparatus, showed that, differently from rolipram and diazepam, selective PDE4D inhibitors, such as compounds 3b, 5b and 7b, did not affect locomotion, whereas compound 1b showed a tendency to reduce the distance traveled and to prolong the immobility period, possibly due to a poor selectivity.

Synthesis, biological evaluation, and molecular modeling of new 3-(cyclopentyloxy)-4-methoxybenzaldehyde O-(2-(2,6-dimethylmorpholino)-2-oxoethyl) Oxime (GEBR-7b) related phosphodiesterase 4D (PDE4D) inhibitors.

A new series of 3-(cyclopentyloxy)-4-methoxyphenyl derivatives, structurally related to our hit GEBR-4a (1) and GEBR-7b (2), has been designed by changing length and functionality of the chain linking the catecholic moiety to the terminal cycloamine portion. Among the numerous molecules synthesized, compounds 8, 10a, and 10b showed increased potency as PDE4D enzyme inhibitors with respect to 2 and a good selectivity against PDE4A4, PDE4B2, and PDE4C2 enzymes, without both cytotoxic and genotoxic effects. The ability to enhance cAMP level in neuronal cells was assessed for compound 8. SAR considerations, also confirmed by in silico docking simulations, evidenced that both chain and amino terminal function characterized by higher hydrophilicity are required for a good and selective inhibitor-catalytic pocket interaction.