Samuele Maramai

Quercetin and ferulic acid are two phytochemicals extensively represented in the plant kingdom and daily consumed in considerable amounts through diets. Due to a common phenolic structure, these two molecules share several pharmacological properties, e.g., antioxidant and free radical scavenging, anti-cancer, anti-inflammatory, anti-arrhythmic, and vasorelaxant. The aim of the present work was the combination of the two molecules in a single chemical entity, conceivably endowed with more efficacious vasorelaxant activity. Preliminary in silico studies herein described suggested that the new hybrid compound bound spontaneously and with high affinity on the KCa1.1 channel. Thus, the synthesis of the 3′-ferulic ester derivative of quercetin was achieved and its structure confirmed by 1H- and 13C-NMR spectra, HSQC and HMBC experiments, mass spectrometry, and elementary analysis. The effect of the new hybrid compound on vascular KCa1.1 and CaV1.2 channels revealed a partial loss of the s...

The unique role of fatty acid amide hydrolase (FAAH) in terminating
endocannabinoid (EC) signaling supports its relevance
as a therapeutic target. Inhibition of EC metabolizing enzymes
elicits indirect agonism of cannabinoid receptors (CBRs) and
therapeutic efficacy devoid of psychotropic effects. Based on
our previous ligands, and aiming at the discovery of new selective
FAAH inhibitors, we developed a series of 12 new compounds
characterized by functionalized tricyclic scaffolds. All
the developed compounds display negligible activity on monoacylglycerol
lipase (MAGL) and CBRs. The most potent FAAH
inhibitors of the newly developed series, 6-oxo-5,6-dihydro-4Hbenzo[
f]pyrrolo[1,2-a][1,4]diazepin-9-yl-6-phenylhexylcarbamate
(5h) and 4-oxo-5,6-dihydro-4H-benzo[f]pyrrolo[1,2-a][1,4]diazepin-
9-yl-(6-phenylhexyl)carbamate (5i) (nanomolar FAAH inhibitors,
the latter of which also shows micromolar affinity at the
CB1R), were selected for further studies. Results of cell-based
studies on a neuroblastoma cell line (IMR32) demonstrated 5h,
5i, and our reference compound 3 ([3-(3-carbamoylpyrrol-1-yl)-
phenyl] N-(5-phenylpentyl)carbamate) to lack any cytotoxic
effect, while all three showed the ability to decrease oxidative
stress by reducing the expression of the redox-sensitive transcription
factor NF-kB. Encouraged by these data, these compounds
were studied in vivo and were dosed orally in a mouse
model of neuropathic pain. At 10 mgkg@1 all the compounds
were able to relieve the hypersensitivity induced by oxaliplatin.

Starting from 1−4 and 7 structural templates, analogues based on bioisosteric replacements (5a−c vs 1, 2 and 6 vs 7) were synthesized for completing the SAR analysis. Interesting binding properties at GluA2, GluK1, and GluK3 receptors were discovered. The requirements for GluK3 interaction were elucidated by determining the X-ray structures of the GluK3-LBD with 2 and 5c and by computational studies. Antinociceptive potential was demonstrated for GluK1 partial agonist 3 and antagonist 7 (2 mg/kg ip).

A computational analysis of the X-ray structure of the low-density
lipoprotein receptor-related protein 6 (LRP6) with the Dickkopf-
1 (DKK1) C-terminal fragment has allowed us to rationally
design a small set of decapeptides. These compounds behave
as agonists of the canonical Wnt pathway in the micromolar
range when tested on a dual luciferase Wnt functional assay in
glioblastoma cells. Two of the oligopeptides showed a lack of cytotoxicity in human primary osteoblasts isolated from
sponge bone tissue (femoral heads or knees of elderly patients).
According to the mechanism of action, the studies revealed
a dose- and time-dependent increase in the viability of
human osteoblasts. These results may indicate a potential therapeutic
application of this class of compounds in the treatment
of bone diseases related to aging, such as osteoporosis

D3 receptors represent a major focus of current drug design and development of therapeutics for dopamine-related pathological states. Their close homology with the D2 receptor subtype makes the development of D3 selective antagonists a challenging task. In this review, we explore the relevance and therapeutic utility of D3 antagonists or partial agonists endowed with multireceptor affinity profile in the field of central nervous system disorders such as schizophrenia and drug abuse. In fact, the peculiar distribution and low brain abundance of D3 receptors make them a valuable target for the development of drugs devoid of motor side effects classically elicited by D2 antagonists. Recent research efforts were devoted to the conception of chemical templates possibly endowed with a multi-target profile, especially with regards to other G-protein-coupled receptors (GPCRs). A comprehensive overview of the recent literature in the field is herein provided. In particular, the evolution of the chemical templates has been tracked, according to the growing advancements in both the structural information and the refinement of the key pharmacophoric elements. The receptor/multireceptor affinity and functional profiles for the examined compounds have been covered, together with their most significant pharmacological applications.

We present herein a novel and convenient route for the scaling-up of the dTuv fragment of pretubulysin. The newly conceived chemical path involves a practical and efficient one-step procedure for the preparation of a key thiazole intermediate, followed by high-yielding Wittig olefination/reduction steps. The optimized route, starting from the inexpensive and non-toxic L-cysteine, encompasses five synthetic steps and only two chromatographic purifications, thus displaying a dramatically increased overall yield. The versatility of the proposed approach also provides new hints for the exploration of pretubulysin derivatives bearing diverse heterocyclic portions.

This paper describes the development of piperazine and 4-aminopiperidine carboxamides/carbamates supported on a pharmacogenic pyrroloquinoxaline scaffold as inhibitors of the endocannabinoid catabolizing enzymes fatty acid amide hydrolase (FAAH) and monoacylglycerol lipase (MAGL). Structure– activity relationships and molecular modelling studies allowed the definition of the structural requirements for dual FAAH/MAGL inhibition and led to the identification of a small set of derivatives (compounds 5e, i, k, m) displaying a balanced inhibitory profile against both enzymes, with compound 5m being the frontrunner of the subset. Favorable calculated physico-chemical properties suggest further investigation for specific analogues.

We report the discovery of compound 4a, a potent β-lactam-based monoacylglycerol lipase (MGL) inhibitor characterized by an irreversible and stereoselective mechanism of action, high membrane permeability, high brain penetration evaluated using a human in vitro blood−brain barrier model, high selectivity in binding and affinity-based proteomic profiling assays, and low in vitro toxicity. Mode-of-action studies demonstrate that 4a, by blocking MGL, increases 2-arachidonoylglycerol and behaves as a cannabinoid (CB1/CB2) receptor indirect agonist. Administration of 4a in mice suffering from experimental autoimmune encephalitis ameliorates the severity of the clinical symptoms in a CB1/CB2-dependent manner. Moreover, 4a produced analgesic effects in a rodent model of acute inflammatory pain, which was antagonized by CB1 and CB2 receptor antagonists/inverse agonists. 4a also relieves the neuropathic hypersensitivity induced by oxaliplatin. Given these evidence, 4a, as MGL selective inhibitor, could represent a valuable lead for the future development of therapeutic options for multiple sclerosis and chronic pain.

Our recent finding that paclitaxel behaves as a peptidomimetic of the endogenous protein Nur77 inspired the design of two peptides (PEP1 and PEP2) reproducing the effects of paclitaxel on Bcl-2 and tubulin, proving the peptidomimetic nature of paclitaxel. Starting from these peptide-hits, we herein describe the synthesis and the biological investigation of linear and cyclic peptides structurally related to PEP2. While linear peptides (2a,b, 3a,b, 4, 6a-f) were found inactive in cell-based assays, biological analysis revealed a pro-apoptotic effect for most of the cyclic peptides (5a-g). Cellular permeability of 5a (and also of 2a,b) on HL60 cells was assessed through confocal microscopy analysis. Further cellular studies on a panel of leukemic cell lines (HL60, Jurkat, MEC, EBVB) and solid tumor cell lines (breast cancer MCF-7 cells, human melanoma A375 and 501Mel cells, and murine melanoma B16F1 cells) confirmed the pro-apoptotic effect of the cyclic peptides. Cell cycle analysis revealed that treatment with 5a, 5c, 5d or 5f resulted in an increase in the number of cells in the sub-G 0 /G 1 peak. Direct interaction with tubulin (turbidimetric assay) and with microtubules (immunostaining experiments) was assessed in vitro for the most promising compounds.

Aim: Histone deacetylases (HDACs) regulate the expression and activity of numerous proteins involved in the initiation and progression of cancer. Currently, three hydroxamate-containing HDAC pan-inhibitors have been approved as antitumor agents. Results: We herein present the development of a series of novel phenylpyrrole-based derivatives stemmed from combined computational and medicinal chemistry efforts to rationally modulate HDAC1/6 isoform selectivity. In vitro activity on HDAC1 and HDAC6 isoforms and the effects of selected analogs on histone H3 and α-tubulin acetylation levels were determined. Cell-based data evidenced, for selected compounds, a promising antitumor potential and low toxicity on normal cells. Conclusion: The newly developed compounds represent a valuable starting point for the development of novel anticancer agents.

The physiological function of kainate receptors (GluK1-GluK5) in the central nervous system is not fully understood yet. With the aim of developing potent and selective GluK1 ligands, we have synthesized a series of new thiophene-based GluK1 agonists (6a-c) and antagonists (7a-d). Pharmacological evaluation revealed that they are selective for the GluK1 subunit, with 7b being the most subtype-selective ligand reported to date (GluK1 vs GluK3). The antagonist 7a was cocrystallized with the GluK1 ligand binding domain, and an X-ray crystallographic analysis revealed the largest flexibility in GluK1 ligand binding domain opening upon binding of a ligand seen to date. The results provide new insights into the molecular mechanism of GluK1 receptor ligand binding and pave the way to the development of new tool compounds for studying kainate receptor function.