Discovery of first novel sigma/HDACi dual-ligands with a potent in vitro antiproliferative activity.

Designing and discovering compounds for dual-target inhibitors is challenging to synthesize new, safer, and more efficient drugs than single-target drugs, especially to treat multifactorial diseases such as cancer. The simultaneous regulation of multiple targets might represent an alternative synthetic approach to optimize patient compliance and tolerance, minimizing the risk of target-based drug resistance due to the modulation of a few targets. To this end, we conceived for the first time the design and synthesis of dual-ligands σR/HDACi to evaluate possible employment as innovative candidates to address this complex disease. Among all synthesized compounds screened for several tumoral cell lines, compound 6 (Kiσ1R = 38 ± 3.7; Kiσ2R = 2917 ± 769 and HDACs IC50 = 0.59 µM) is the most promising candidate as an antiproliferative agent with an IC50 of 0.9 µM on the HCT116 cell line and no significant toxicity to normal cells. Studies of molecular docking, which confirmed the affinity over σ1R and a pan-HDACs inhibitory behavior, support a possible balanced affinity and activity between both targets.

Generation and Reactions of an Octacyclic Hindered Pyramidalized Alkene.

Octacyclo[10.6.1.01,10.03,7.04,9.08,19.011,16.013,17]nonadeca-5,8,14-triene (27), a hindered pyramidalized alkene, has been generated from a diiodide precursor. Contrary to the usual behavior of known pyramidalized alkenes, no Diels-Alder adducts were obtained from the present alkene when it was generated by different standard procedures in the presence of different dienes. However, products derived from the reduction, t-BuLi addition, condensation with the solvent, or dimerization were isolated from these reactions, depending on the conditions used to generate it. No [2 + 2] cross product among this pyramidalized alkene and tricyclo[3.3.1.03,7]non-3(7)-ene was formed when a mixture of the corresponding precursor diiodides was reacted with sodium amalgam. The analysis of selected geometrical and orbital parameters determined from quantum mechanical calculations indicates that the degree of pyramidalization of this alkene and its higher steric hindrance compared with other polycyclic pyramidalized alkenes may explain its peculiar reactivity.

A Structure- and Ligand-Based Virtual Screening of a Database of "Small" Marine Natural Products for the Identification of "Blue" Sigma-2 Receptor Ligands.

Sigma receptors are a fascinating receptor protein class whose ligands are actually under clinical evaluation for the modulation of opioid analgesia and their use as positron emission tomography radiotracers. In particular, peculiar biological and therapeutic functions are associated with the sigma-2 (σ2) receptor. The σ2 receptor ligands determine tumor cell death through apoptotic and non-apoptotic pathways, and the overexpression of σ2 receptors in several tumor cell lines has been well documented, with significantly higher levels in proliferating tumor cells compared to quiescent ones. This acknowledged feature has found practical application in the development of cancer cell tracers and for ligand-targeting therapy. In this context, the development of new ligands that target the σ2 receptors is beneficial for those diseases in which this protein is involved. In this paper, we conducted a search of new potential σ2 receptor ligands among a database of 1517 "small" marine natural products constructed by the union of the Seaweed Metabolite and the Chemical Entities of Biological Interest (ChEBI) Databases. The structures were passed through two filters that were constituted by our developed two-dimensional (2D) and three-dimensional Quantitative Structure-Activity Relationship (3D-QSAR) statistical models, and successively docked upon a σ2 receptor homology model that we built according to the FASTA sequence of the σ2/TMEM97 (SGMR2_HUMAN) receptor.

In vitro and in vivo studies of ocular topically administered NLC for the treatment of uveal melanoma.

Uveal melanoma is one of the most common and aggressive intraocular malignancies, and, due to its great capability of metastasize, it constitutes the most incident intraocular tumor in adults. However, to date there is no effective treatment since achieving the inner ocular tissues still constitutes one of the greatest challenges in actual medicine, because of the complex structure and barriers. Uncoated and PEGylated nanostructured lipid carriers were developed to achieve physico-chemical properties (mean particle size, homogeneity, zeta potential, pH and osmolality) compatible for the ophthalmic administration of (S)-(-)-MRJF22, a new custom-synthetized prodrug for the potential treatment of uveal melanoma. The colloidal physical stability was investigated at different temperatures by Turbiscan® Ageing Station. Morphology analysis and mucoadhesive studies highlighted the presence of small particles suitable to be topically administered on the ocular surface. In vitro release studies performed using Franz diffusion cells demonstrated that the systems were able to provide a slow and prolonged prodrug release. In vitro cytotoxicity test on Human Corneal Epithelium and Human Uveal Melanoma cell lines and Hen's egg-chorioallantoic membrane test showed a dose-dependent cytotoxic effect of the free prodrug on corneal cells, whose cytocompatibility improved when encapsulated into nanoparticles, as also confirmed by in vivo studies on New Zealand albino rabbits. Antiangiogenic capability and preventive anti-inflammatory properties were also investigated on embryonated eggs and rabbits, respectively. Furthermore, preliminary in vivo biodistribution images of fluorescent nanoparticles after topical instillation in rabbits' eyes, suggested their ability to reach the posterior segment of the eye, as a promising strategy for the treatment of choroidal uveal melanoma.

Synthesis, Computational Insights, and Evaluation of Novel Sigma Receptors Ligands.

The development of diazabicyclo[4.3.0]nonane and 2,7-diazaspiro[3.5]nonane derivatives as sigma receptors (SRs) ligands is reported. The compounds were evaluated in S1R and S2R binding assays, and modeling studies were carried out to analyze the binding mode. The most notable compounds, 4b (AD186, KiS1R = 2.7 nM, KiS2R = 27 nM), 5b (AB21, KiS1R = 13 nM, KiS2R = 102 nM), and 8f (AB10, KiS1R = 10 nM, KiS2R = 165 nM), have been screened for analgesic effects in vivo, and their functional profile was determined through in vivo and in vitro models. Compounds 5b and 8f reached the maximum antiallodynic effect at 20 mg/kg. The selective S1R agonist PRE-084 completely reversed their action, indicating that the effects are entirely dependent on the S1R antagonism. Conversely, compound 4b sharing the 2,7-diazaspiro[3.5]nonane core as 5b was completely devoid of antiallodynic effect. Interestingly, compound 4b fully reversed the antiallodynic effect of BD-1063, indicating that 4b induces an S1R agonistic in vivo effect. The functional profiles were confirmed by the phenytoin assay. Our study might establish the importance of 2,7-diazaspiro[3.5]nonane core for the development of S1R compounds with specific agonist or antagonist profile and the role of the diazabicyclo[4.3.0]nonane in the development of novel SR ligands.

Dual Sigma-1 receptor antagonists and hydrogen sulfide-releasing compounds for pain treatment: Design, synthesis, and pharmacological evaluation.

The development of σ1 receptor antagonists hybridized with a H2S-donor is here reported. We aimed to obtain improved analgesic effects when compared to σ1 receptor antagonists or H2S-donors alone. In an in vivo model of sensory hypersensitivity, thioamide 1a induced analgesia which was synergistically enhanced when associated with the σ1 receptor antagonist BD-1063. The selective σ1 receptor agonist PRE-084 completely reversed this effect. Four thioamide H2S-σ1 receptor hybrids (5a-8a) and their amide derivatives (5b-8b) were synthesized. Compound 7a (AD164) robustly released H2S and showed selectivity for σ1 receptor over σ2 and opioid receptors. This compound induced marked analgesia that was reversed by PRE-084. The amide analogue 7b (AD163) showed only minimal analgesia. Further studies showed that 7a exhibited negligible acute toxicity, together with a favorable pharmacokinetic profile. To the best of our knowledge, compound 7a is the first dual-acting ligand with simultaneous H2S-release and σ1 antagonistic activities.

Interaction of new sigma ligands with biomembrane models evaluated by differential scanning calorimetry and Langmuir-Blodgett studies.

The compound (+)-MR200 [(+)-methyl (1R,2S)-2-{[4-(4-chlorophenyl)-4-hydroxypiperidin-1-yl]methyl}-1-phenylcyclopropanecarboxylate] is a selective sigma 1 (σ1) antagonist with antinociceptive effect, able to increase selective opioid receptor agonist-mediated analgesia. The parent compound (-)-MRV3 [(-)-methyl (1S,2R)-2-[(4-hydroxy-4-phenylpiperidin-1-yl)-methyl]-1-phenylcyclopropanecarboxylate], a σ1 antagonist with an improved σ1/σ2 selectivity respect to (+)-MR200, play a role in both central sensitization and pain hypersensitivity, suggesting a potential use of σ1 antagonists for the treatment of persistent pain conditions. With the intention to assessing the membrane absorption of compounds and their ability to cross it, the interaction of (+)-MR200 and (-)-MRV3 with dimyristoylphosphatidylcholine phospholipids (DMPC), used as biomembrane models was studied by Differential Scanning Calorimetry (DSC) and Langmuir-Blodgett (LB).

Haloperidol Metabolite II Valproate Ester (S)-(-)-MRJF22: Preliminary Studies as a Potential Multifunctional Agent Against Uveal Melanoma.

Increased angiogenesis and vascular endothelial growth factor (VEGF) levels contribute to higher metastasis and mortality in uveal melanoma (UM), an aggressive malignancy of the eye in adults. (±)-MRJF22, a prodrug of the sigma (σ) ligand haloperidol metabolite II conjugated with the histone deacetylase (HDAC) inhibitor valproic acid, has previously demonstrated a promising antiangiogenic activity. Herein, the asymmetric synthesis of (R)-(+)-MRJF22 and (S)-(-)-MRJF22 was performed to investigate their contribution to (±)-MRJF22 antiangiogenic effects in human retinal endothelial cells (HREC) and to assess their therapeutic potential in primary human uveal melanoma (UM) 92-1 cell line. While both enantiomers displayed almost identical capabilities to reduce cell viability than the racemic mixture, (S)-(-)-MRJF22 exhibited the highest antimigratory effects in endothelial and tumor cells. Given the fundamental contribution of cell motility to cancer progression, (S)-(-)-MRJF22 may represent a promising candidate for novel antimetastatic therapy in patients with UM.

Nitric Oxide Photo-Donor Hybrids of Ciprofloxacin and Norfloxacin: A Shift in Activity from Antimicrobial to Anticancer Agents.

The potential anticancer effect of fluoroquinolone antibiotics has been recently unveiled and related to their ability to interfere with DNA topoisomerase II. We herein envisioned the design and synthesis of novel Ciprofloxacin and Norfloxacin nitric oxide (NO) photo-donor hybrids to explore the potential synergistic antitumor effect exerted by the fluoroquinolone scaffold and NO eventually produced upon light irradiation. Anticancer activity, evaluated on a panel of tumor cell lines, showed encouraging results with IC50 values in the low micromolar range. Some compounds displayed intense antiproliferative activity on triple-negative and doxorubicin-resistant breast cancer cell lines, paving the way for their potential use to treat aggressive, refractory and multidrug-resistant breast cancer. No significant additive effect was observed on PC3 and DU145 cells following NO release. Conversely, antimicrobial photodynamic experiments on both Gram-negative and Gram-positive microorganisms displayed a significant killing rate in Staphylococcus aureus, accounting for their potential effectiveness as selective antimicrobial photosensitizers.