Voltage-Gated K+ Channel Modulation by Marine Toxins: Pharmacological Innovations and Therapeutic Opportunities.

Bioactive compounds are abundant in animals originating from marine ecosystems. Ion channels, which include sodium, potassium, calcium, and chloride, together with their numerous variants and subtypes, are the primary molecular targets of the latter. Based on their cellular targets, these venom compounds show a range of potencies and selectivity and may have some therapeutic properties. Due to their potential as medications to treat a range of (human) diseases, including pain, autoimmune disorders, and neurological diseases, marine molecules have been the focus of several studies over the last ten years. The aim of this review is on the various facets of marine (or marine-derived) molecules, ranging from structural characterization and discovery to pharmacology, culminating in the development of some "novel" candidate chemotherapeutic drugs that target potassium channels.

In Silico Methods for the Discovery of Kv7.2/7.3 Channels Modulators: A Comprehensive Review.

The growing interest in Kv7.2/7.3 agonists originates from the involvement of these channels in several brain hyperexcitability disorders. In particular, Kv7.2/7.3 mutants have been clearly associated with epileptic encephalopathies (DEEs) as well as with a spectrum of focal epilepsy disorders, often associated with developmental plateauing or regression. Nevertheless, there is a lack of available therapeutic options, considering that retigabine, the only molecule used in clinic as a broad-spectrum Kv7 agonist, has been withdrawn from the market in late 2016. This is why several efforts have been made both by both academia and industry in the search for suitable chemotypes acting as Kv7.2/7.3 agonists. In this context, in silico methods have played a major role, since the precise structures of different Kv7 homotetramers have been only recently disclosed. In the present review, the computational methods used for the design of Kv.7.2/7.3 small molecule agonists and the underlying medicinal chemistry are discussed in the context of their biological and structure-function properties.

A Comprehensive In Vitro Characterization of a New Class of Indole-Based Compounds Developed as Selective Haspin Inhibitors.

Haspin is an emerging, but rather unexplored, divergent kinase involved in tumor growth by regulating the mitotic phase. In this paper, the in-silico design, synthesis, and biological characterization of a new series of substituted indoles acting as potent Haspin inhibitors are reported. The synthesized derivatives have been evaluated by FRET analysis, showing very potent Haspin inhibition. Then, a comprehensive in-cell investigation highlighted compounds 47 and 60 as the most promising inhibitors. These compounds were challenged for their synergic activity with paclitaxel in 2D and 3D cellular models, demonstrating a twofold improvement of the paclitaxel antitumor activity. Compound 60 also showed remarkable selectivity when tested in a panel of 70 diverse kinases. Finally, in-silico studies provided new insight about the chemical requirements useful to develop new Haspin inhibitors. Biological results, together with the drug-likeness profile of 47 and 60, make these derivatives deserving further studies.

KCNT1 Channel Blockers: A Medicinal Chemistry Perspective.

Potassium channels have recently emerged as suitable target for the treatment of epileptic diseases. Among potassium channels, KCNT1 channels are the most widely characterized as responsible for several epileptic and developmental encephalopathies. Nevertheless, the medicinal chemistry of KCNT1 blockers is underdeveloped so far. In the present review, we describe and analyse the papers addressing the issue of KCNT1 blockers' development and identification, also evidencing the pros and the cons of the scientific approaches therein described. After a short introduction describing the epileptic diseases and the structure-function of potassium channels, we provide an extensive overview of the chemotypes described so far as KCNT1 blockers, and the scientific approaches used for their identification.

In Silico Assisted Identification, Synthesis, and In Vitro Pharmacological Characterization of Potent and Selective Blockers of the Epilepsy-Associated KCNT1 Channel.

Gain-of-function (GoF) variants in KCNT1 channels cause severe, drug-resistant forms of epilepsy. Quinidine is a known KCNT1 blocker, but its clinical use is limited due to severe drawbacks. To identify novel KCNT1 blockers, a homology model of human KCNT1 was built and used to screen an in-house library of compounds. Among the 20 molecules selected, five (CPK4, 13, 16, 18, and 20) showed strong KCNT1-blocking ability in an in vitro fluorescence-based assay. Patch-clamp experiments confirmed a higher KCNT1-blocking potency of these compounds when compared to quinidine, and their selectivity for KCNT1 over hERG and Kv7.2 channels. Among identified molecules, CPK20 displayed the highest metabolic stability; this compound also blocked KCNT2 currents, although with a lower potency, and counteracted GoF effects prompted by 2 recurrent epilepsy-causing KCNT1 variants (G288S and A934T). The present results provide solid rational basis for future design of novel compounds to counteract KCNT1-related neurological disorders.

Novel pyrrole based CB2 agonists: New insights on CB2 receptor role in regulating neurotransmitters' tone.

The cannabinoid system is one of the most investigated neuromodulatory systems because of its involvement in multiple pathologies such as cancer, inflammation, and psychiatric diseases. Recently, the CB2 receptor has gained increased attention considering its crucial role in modulating neuroinflammation in several pathological conditions like neurodegenerative diseases. Here we describe the rational design of pyrrole-based analogues, which led to a potent and pharmacokinetically suitable CB2 full agonist particularly effective in improving cognitive functions in a scopolamine-induced amnesia murine model. Therefore, we extended our study by investigating the interconnection between CB2 activation and neurotransmission in this experimental paradigm. To this purpose, we performed a MALDI imaging analysis on mice brains, observing that the administration of our lead compound was able to revert the effect of scopolamine on different neurotransmitter tones, such as acetylcholine, serotonin, and GABA, shedding light on important networks not fully explored, so far.

Peptidomimetics as potent dual SARS-CoV-2 cathepsin-L and main protease inhibitors: In silico design, synthesis and pharmacological characterization.

In this paper we present the design, synthesis, and biological evaluation of a new series of peptidomimetics acting as potent anti-SARS-CoV-2 agents. Starting from our previously described Main Protease (MPro) and Papain Like Protease (PLPro) dual inhibitor, CV11, here we disclose its high inhibitory activity against cathepsin L (CTSL) (IC50 = 19.80 ± 4.44 nM), an emerging target in SARS-CoV-2 infection machinery. An in silico design, inspired by the structure of CV11, led to the development of a library of peptidomimetics showing interesting activities against CTSL and Mpro, allowing us to trace the chemical requirements for the binding to both enzymes. The screening in Vero cells infected with 5 different SARS-CoV-2 variants of concerns, highlighted sub-micromolar activities for most of the synthesized compounds (13, 15, 16, 17 and 31) in agreement with the enzymatic inhibition assays results. The compounds showed lack of activity against several different RNA viruses except for the 229E and OC43 human coronavirus strains, also characterized by a cathepsin-L dependent release into the host cells. The most promising derivatives were also evaluated for their chemical and metabolic in-vitro stability, with derivatives 15 and 17 showing a suitable profile for further preclinical characterization.

A Combination of Polymethoxyflavones from Citrus sinensis and Prenylflavonoids from Humulus lupulus Counteracts IL-1ß-Induced Differentiated Caco-2 Cells Dysfunction via a Modulation of NF-κB/Nrf2 Activation.

We here investigated the anti-inflammatory activity of a polymethoxylated flavone-containing fraction (PMFF) from Citrus sinensis and of a prenylflavonoid-containing one (PFF) from Humulus lupulus, either alone or in combination (MIX). To this end, an in vitro model of inflammatory bowel disease (IBD), consisting of differentiated, interleukin (IL)-1ß-stimulated Caco-2 cells, was employed. We demonstrated that non-cytotoxic concentrations of either PMFF or PFF or MIX reduced nitric oxide (NO) production while PFF and MIX, but not PMFF, also inhibited prostaglandin E2 release. Coherently, MIX suppressed both inducible NO synthase and cyclooxygenase-2 over-expression besides NF-κB activation. Moreover, MIX increased nuclear factor erythroid 2-related factor 2 (Nrf2) activation, heme oxygenase-1 expression, restoring GSH and reactive oxygen and nitrogen species (RONs) levels. Remarkably, these effects with MIX were stronger than those produced by PMFF or PFF alone. Noteworthy, nobiletin (NOB) and xanthohumol (XTM), two of the most represented phytochemicals in PMFF and PFF, respectively, synergistically inhibited RONs production. Overall, our results demonstrate that MIX enhances the anti-inflammatory and anti-oxidative effects of the individual fractions in a model of IBD, via a mechanism involving modulation of NF-κB and Nrf2 signalling. Synergistic interactions between NOB and XTM emerge as a relevant aspect underlying this evidence.

Design, Synthesis, and Pharmacological Characterization of a Potent Soluble Epoxide Hydrolase Inhibitor for the Treatment of Acute Pancreatitis.

Acute pancreatitis (AP) is a potentially life-threatening illness characterized by an exacerbated inflammatory response with limited options for pharmacological treatment. Here, we describe the rational development of a library of soluble epoxide hydrolase (sEH) inhibitors for the treatment of AP. Synthesized compounds were screened in vitro for their sEH inhibitory potency and selectivity, and the results were rationalized by means of molecular modeling studies. The most potent compounds were studied in vitro for their pharmacokinetic profile, where compound 28 emerged as a promising lead. In fact, compound 28 demonstrated a remarkable in vivo efficacy in reducing the inflammatory damage in cerulein-induced AP in mice. Targeted metabololipidomic analysis further substantiated sEH inhibition as a molecular mechanism of the compound underlying anti-AP activity in vivo. Finally, pharmacokinetic assessment demonstrated a suitable profile of 28 in vivo. Collectively, compound 28 displays strong effectiveness as sEH inhibitor with potential for pharmacological AP treatment.

Combination of Spirulina platensis, Ganoderma lucidum and Moringa oleifera Improves Cardiac Functions and Reduces Pro-Inflammatory Biomarkers in Preclinical Models of Short-Term Doxorubicin-Mediated Cardiotoxicity: New Frontiers in Cardioncology?

Anthracyclines are essential adjuvant therapies for a variety of cancers, particularly breast, gastric and esophageal cancers. Whilst prolonging cancer-related survival, these agents can induce drug-related cardiotoxicity. Spirulina, Reishi (Ganoderma lucidum) and Moringa are three nutraceuticals with anti-inflammatory effects that are currently used in cancer patients as complementary and alternative medicines to improve quality of life and fatigue. We hypothesize that the nutraceutical combination of Spirulina, Reishi and Moringa (Singo) could reduce inflammation and cardiotoxicity induced by anthracyclines. Female C57Bl/6 mice were untreated (Sham, n = 6) or treated for 7 days with short-term doxorubicin (DOXO, n = 6) or Singo (Singo, n = 6), or pre-treated with Singo for 3 days and associated with DOXO for remaining 7 days (DOXO−Singo, n = 6). The ejection fraction and radial and longitudinal strain were analyzed through transthoracic echocardiography (Vevo 2100, Fujifilm, Tokyo, Japan). The myocardial expressions of NLRP3, DAMPs (galectin-3 and calgranulin S100) and 13 cytokines were quantified through selective mouse ELISA methods. Myocardial fibrosis, necrosis and hypertrophy were analyzed through immunohistochemistry (IHC). Human cardiomyocytes were exposed to DOXO (200 nM) alone or in combination with Singo (at 10, 25 and 50 µg/mL) for 24 and 48 h. Cell viability and inflammation studies were also performed. In preclinical models, Singo significantly improved ejection fraction and fractional shortening. Reduced expressions of myocardial NLRP3 and NF-kB levels in cardiac tissues were seen in DOXO−Singo mice vs. DOXO (p < 0.05). The myocardial levels of calgranulin S100 and galectin-3 were strongly reduced in DOXO−Singo mice vs. DOXO (p < 0.05). Immunohistochemistry analysis indicates that Singo reduces fibrosis and hypertrophy in the myocardial tissues of mice during exposure to DOXO. In conclusion, in the preclinical model of DOXO-induced cardiotoxicity, Singo is able to improve cardiac function and reduce biomarkers involved in heart failure and fibrosis.

Discovery and Optimization of Indoline-Based Compounds as Dual 5-LOX/sEH Inhibitors: In Vitro and In Vivo Anti-Inflammatory Characterization.

The design of multitarget drugs represents a promising strategy in medicinal chemistry and seems particularly suitable for the discovery of anti-inflammatory drugs. Here, we describe the identification of an indoline-based compound inhibiting both 5-lipoxygenase (5-LOX) and soluble epoxide hydrolase (sEH). In silico analysis of an in-house library identified nine compounds as potential 5-LOX inhibitors. Enzymatic and cellular assays revealed the indoline derivative 43 as a notable 5-LOX inhibitor, guiding the design of new analogues. These compounds underwent extensive in vitro investigation revealing dual 5-LOX/sEH inhibitors, with 73 showing the most promising activity (IC50s of 0.41 ± 0.01 and 0.43 ± 0.10 µM for 5-LOX and sEH, respectively). When challenged in vivo in zymosan-induced peritonitis and experimental asthma in mice, compound 73 showed remarkable anti-inflammatory efficacy. These results pave the way for the rational design of 5-LOX/sEH dual inhibitors and for further investigation of their potential use as anti-inflammatory agents.

Beyond Retigabine: Design, Synthesis, and Pharmacological Characterization of a Potent and Chemically Stable Neuronal Kv7 Channel Activator with Anticonvulsant Activity.

Neuronal Kv7 channels represent important pharmacological targets for hyperexcitability disorders including epilepsy. Retigabine is the prototype Kv7 activator clinically approved for seizure treatment; however, severe side effects associated with long-term use have led to its market discontinuation. Building upon the recently described cryoEM structure of Kv7.2 complexed with retigabine and on previous structure-activity relationship studies, a small library of retigabine analogues has been designed, synthesized, and characterized for their Kv7 opening ability using both fluorescence- and electrophysiology-based assays. Among all tested compounds, 60 emerged as a potent and photochemically stable neuronal Kv7 channel activator. Compared to retigabine, compound 60 displayed a higher brain/plasma distribution ratio, a longer elimination half-life, and more potent and effective anticonvulsant effects in an acute seizure model in mice. Collectively, these data highlight compound 60 as a promising lead compound for the development of novel Kv7 activators for the treatment of hyperexcitability diseases.

New TRPM8 blockers exert anticancer activity over castration-resistant prostate cancer models.

TRPM8 has recently emerged as a druggable target in prostate cancer (PC) and TRPM8 modulators have been proposed as potential anticancer agents in this pathology. We have recently demonstrated their effectiveness in a castration-resistant prostate cancer (CRPC) model that is usually resistant to androgen deprivation therapy (ADT) and is considered the most aggressive form of PC. This is why the discovery of selective, effective, and potent TRPM8 modulators would improve the molecular arsenal in support of PC standard-of-care treatments. In the present paper we describe the design and the synthesis of a new series of TRPM8 antagonists, preliminarily characterized in vitro for their potency and selectivity by fluorimetric calcium assays. The preliminary screening allowed the identification of several potent (0.11 µM < IC50 < 0.49 µM) and selective compounds. The most potent derivatives were further characterized by patch-clamp electrophysiology assays, confirming their noteworthy activity. Moreover, the behavior of these compounds was investigated in 2D and 3D models of PC. These TRPM8 antagonists showed remarkable efficacy in inhibiting the growth induced by androgen in various PC cells as well as in CRPC models, confirming their potential as anticancer agents.

Metabolomics-assisted discovery of a new anticancer GLS-1 inhibitor chemotype from a nortopsentin-inspired library: From phenotype screening to target identification.

The enzyme glutaminase-1 (GLS-1) has shown a clear and coherent implication in the progression and exacerbation of different aggressive tumors such as glioblastoma, hepatocarcinoma, pancreas, bone, and triple-negative breast cancer. Few chemotypes are currently available as selective GLS-1 inhibitors, and still, fewer of them are at the clinical stage. In the present paper, starting from a naturally-inspired antitumor compound library, metabolomics has been used to putatively identify the molecular mechanism underlying biological activity. GLS-1 was identified as a potential target. Biochemical analysis confirmed the hypothesis leading to the identification of a new hit compound acting as a GLS-1 selective inhibitor (IC50 = 3.96 ± 1.05 µM), compared to the GLS-2 isoform (IC50 = 12.90 ± 0.87 µM), with remarkable antitumor potency over different aggressive tumor cell lines. Molecular modelling studies revealed new insight into the drug-target interaction providing robust SAR clues for the rational hit-to-lead development. The approach undertaken underlines the wide potential of metabolomics applied to drug discovery, particularly in target identification and hit discovery following phenotype screening.

In Vitro and In Vivo Pharmacological Characterization of a Novel TRPM8 Inhibitor Chemotype Identified by Small-Scale Preclinical Screening.

Transient receptor potential melastatin type 8 (TRPM8) is a target for the treatment of different physio-pathological processes. While TRPM8 antagonists are reported as potential drugs for pain, cancer, and inflammation, to date only a limited number of chemotypes have been investigated and thus a limited number of compounds have reached clinical trials. Hence there is high value in searching for new TRPM8 antagonistic to broaden clues to structure-activity relationships, improve pharmacological properties and explore underlying molecular mechanisms. To address this, the EDASA Scientific in-house molecular library has been screened in silico, leading to identifying twenty-one potentially antagonist compounds of TRPM8. Calcium fluorometric assays were used to validate the in-silico hypothesis and assess compound selectivity. Four compounds were identified as selective TRPM8 antagonists, of which two were dual-acting TRPM8/TRPV1 modulators. The most potent TRPM8 antagonists (BB 0322703 and BB 0322720) underwent molecular modelling studies to highlight key structural features responsible for drug-protein interaction. The two compounds were also investigated by patch-clamp assays, confirming low micromolar potencies. The most potent compound (BB 0322703, IC50 1.25 ± 0.26 µM) was then profiled in vivo in a cold allodinya model, showing pharmacological efficacy at 30 µM dose. The new chemotypes identified showed remarkable pharmacological properties paving the way to further investigations for drug discovery and pharmacological purposes.

New Frontiers on ER Stress Modulation: Are TRP Channels the Leading Actors?

The endoplasmic reticulum (ER) is a dynamic structure, playing multiple roles including calcium storage, protein synthesis and lipid metabolism. During cellular stress, variations in ER homeostasis and its functioning occur. This condition is referred as ER stress and generates a cascade of signaling events termed unfolded protein response (UPR), activated as adaptative response to mitigate the ER stress condition. In this regard, calcium levels play a pivotal role in ER homeostasis and therefore in cell fate regulation since calcium signaling is implicated in a plethora of physiological processes, but also in disease conditions such as neurodegeneration, cancer and metabolic disorders. A large body of emerging evidence highlighted the functional role of TRP channels and their ability to promote cell survival or death depending on endoplasmic reticulum stress resolution, making them an attractive target. Thus, in this review we focused on the TRP channels' correlation to UPR-mediated ER stress in disease pathogenesis, providing an overview of their implication in the activation of this cellular response.

In Silico Identification and In Vitro Evaluation of New ABCG2 Transporter Inhibitors as Potential Anticancer Agents.

Different molecular mechanisms contribute to the development of multidrug resistance in cancer, including increased drug efflux, enhanced cellular repair mechanisms and alterations of drug metabolism or drug targets. ABCG2 is a member of the ATP-binding cassette superfamily transporters that promotes drug efflux, inducing chemotherapeutic resistance in malignant cells. In this context, the development of selective ABCG2 inhibitors might be a suitable strategy to improve chemotherapy efficacy. Thus, through a multidisciplinary approach, we identified a new ABCG2 selective inhibitor (8), highlighting its ability to increase mitoxantrone cytotoxicity in both hepatocellular carcinoma (EC50from 8.67 ± 2.65 to 1.25 ± 0.80 µM) and transfected breast cancer cell lines (EC50from 9.92 ± 2.32 to 2.45 ± 1.40 µM). Moreover, mitoxantrone co-administration in both transfected and non-transfected HEK293 revealed that compound 8 notably lowered the mitoxantrone EC50, demonstrating its efficacy along with the importance of the ABCG2 extrusion pump overexpression in MDR reversion. These results were corroborated by evaluating the effect of inhibitor 8 on mitoxantrone cell uptake in multicellular tumor spheroids and via proteomic experiments.

Therapeutic potential of TRPM8 antagonists in prostate cancer.

Transient receptor potential melastatin-8 (TRPM8) represents an emerging target in prostate cancer, although its mechanism of action remains unclear. Here, we have characterized and investigated the effects of TRPM8 modulators in prostate cancer aggressiveness disclosing the molecular mechanism underlying their biological activity. Patch-clamp and calcium fluorometric assays were used to characterize the synthesized compounds. Androgen-stimulated prostate cancer-derived cells were challenged with the compounds and the DNA synthesis was investigated in a preliminary screening. The most effective compounds were then employed to inhibit the pro-metastatic behavior of in various PC-derived cells, at different degree of malignancy. The effect of the compounds was then assayed in prostate cancer cell-derived 3D model and the molecular targets of selected compounds were lastly identified using transcriptional and non-transcriptional reporter assays. TRPM8 antagonists inhibit the androgen-dependent prostate cancer cell proliferation, migration and invasiveness. They are highly effective in reverting the androgen-induced increase in prostate cancer cell spheroid size. The compounds also revert the proliferation of castrate-resistant prostate cancer cells, provided they express the androgen receptor. In contrast, no effects were recorded in prostate cancer cells devoid of the receptor. Selected antagonists interfere in non-genomic androgen action and abolish the androgen-induced androgen receptor/TRPM8 complex assembly as well as the increase in intracellular calcium levels in prostate cancer cells. Our results shed light in the processes controlling prostate cancer progression and make the transient receptor potential melastatin-8 as a 'druggable' target in the androgen receptor-expressing prostate cancers.

l-Arginine Improves Solubility and ANTI SARS-CoV-2 Mpro Activity of Rutin but Not the Antiviral Activity in Cells.

The COVID-19 pandemic outbreak prompts an urgent need for efficient therapeutics, and repurposing of known drugs has been extensively used in an attempt to get to anti-SARS-CoV-2 agents in the shortest possible time. The glycoside rutin shows manifold pharmacological activities and, despite its use being limited by its poor solubility in water, it is the active principle of many pharmaceutical preparations. We herein report our in silico and experimental investigations of rutin as a SARS-CoV-2 Mpro inhibitor and of its water solubility improvement obtained by mixing it with l-arginine. Tests of the rutin/l-arginine mixture in a cellular model of SARS-CoV-2 infection highlighted that the mixture still suffers from unfavorable pharmacokinetic properties, but nonetheless, the results of this study suggest that rutin might be a good starting point for hit optimization.

Identification of a dual acting SARS-CoV-2 proteases inhibitor through in silico design and step-by-step biological characterization.

COVID-19 pandemic, starting from the latest 2019, and caused by SARS-CoV-2 pathogen, led to the hardest health-socio-economic disaster in the last century. Despite the tremendous scientific efforts, mainly focused on the development of vaccines, identification of potent and efficient anti-SARS-CoV-2 therapeutics still represents an unmet need. Remdesivir, an anti-Ebola drug selected from a repurposing campaign, is the only drug approved, so far, for the treatment of the infection. Nevertheless, WHO in later 2020 has recommended against its use in COVID-19. In the present paper, we describe a step-by-step in silico design of a small library of compounds as main protease (Mpro) inhibitors. All the molecules were screened by an enzymatic assay on Mpro and, then, cellular activity was evaluated using Vero cells viral infection model. The cellular screening disclosed compounds 29 and 34 as in-vitro SARS-CoV-2 replication inhibitors at non-toxic concentrations (0.32 < EC50 < 5.98 µM). To rationalize these results, additional in-vitro assays were performed, focusing on papain like protease (PLpro) and spike protein (SP) as potential targets for the synthesized molecules. This pharmacological workflow allowed the identification of compound 29, as a dual acting SARS-CoV-2 proteases inhibitor featuring micromolar inhibitory potency versus Mpro (IC50 = 1.72 µM) and submicromolar potency versus PLpro (IC50 = 0.67 µM), and of compound 34 as a selective SP inhibitor (IC50 = 3.26 µM).