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T-type calcium (CaV3) channels are involved in cardiac automaticity, development, and excitation-contraction coupling in normal cardiac myocytes. Their functional role becomes more pronounced in the process of pathological cardiac hypertrophy and heart failure. Currently, no CaV3 channel inhibitors are used in clinical settings. To identify novel T-type calcium channel ligands, purpurealidin analogs were electrophysiologically investigated. These compounds are alkaloids produced as secondary metabolites by marine sponges, and they exhibit a broad range of biological activities. In this study, we identified the inhibitory effect of purpurealidin I (1) on the rat CaV3.1 channel and conducted structure-activity relationship studies by characterizing the interaction of 119 purpurealidin analogs. Next, the mechanism of action of the four most potent analogs was investigated. Analogs 74, 76, 79, and 99 showed a potent inhibition on the CaV3.1 channel with IC50's at approximately 3 µM. No shift of the activation curve could be observed, suggesting that these compounds act like a pore blocker obstructing the ion flow by binding in the pore region of the CaV3.1 channel. A selectivity screening showed that these analogs are also active on hERG channels. Collectively, a new class of CaV3 channel inhibitors has been discovered and the structure-function studies provide new insights into the synthetic design of drugs and the mechanism of interaction with T-type CaV channels.
Assuntos
Poríferos , Ratos , Animais , Miócitos Cardíacos/metabolismoRESUMO
Two decades of research have proven the relevance of ion channel expression for tumor progression in virtually every indication, and it has become clear that inhibition of specific ion channels will eventually become part of the oncology therapeutic arsenal. However, ion channels play relevant roles in all aspects of physiology, and specificity for the tumor tissue remains a challenge to avoid undesired effects. Eag1 (KV 10.1) is a voltage-gated potassium channel whose expression is very restricted in healthy tissues outside of the brain, while it is overexpressed in 70% of human tumors. Inhibition of Eag1 reduces tumor growth, but the search for potent inhibitors for tumor therapy suffers from the structural similarities with the cardiac HERG channel, a major off-target. Existing inhibitors show low specificity between the two channels, and screenings for Eag1 binders are prone to enrichment in compounds that also bind HERG. Rational drug design requires knowledge of the structure of the target and the understanding of structure-function relationships. Recent studies have shown subtle structural differences between Eag1 and HERG channels with profound functional impact. Thus, although both targets' structure is likely too similar to identify leads that exclusively bind to one of the channels, the structural information combined with the new knowledge of the functional relevance of particular residues or areas suggests the possibility of selective targeting of Eag1 in cancer therapies. Further development of selective Eag1 inhibitors can lead to first-in-class compounds for the treatment of different cancers.
Assuntos
Canais de Potássio Éter-A-Go-Go , Neoplasias , Canais de Potássio Éter-A-Go-Go/metabolismo , Humanos , Neoplasias/tratamento farmacológicoRESUMO
The KV 1.3 voltage-gated potassium ion channel is involved in many physiological processes both at the plasma membrane and in the mitochondria, chiefly in the immune and nervous systems. Therapeutic targeting KV 1.3 with specific peptides and small molecule inhibitors shows great potential for treating cancers and autoimmune diseases, such as multiple sclerosis, type I diabetes mellitus, psoriasis, contact dermatitis, rheumatoid arthritis, and myasthenia gravis. However, no KV 1.3-targeted compounds have been approved for therapeutic use to date. This review focuses on the presentation of approaches for discovering new KV 1.3 peptide and small-molecule inhibitors, and strategies to improve the selectivity of active compounds toward KV 1.3. Selectivity of dalatazide (ShK-186), a synthetic derivate of the sea anemone toxin ShK, was achieved by chemical modification and has successfully reached clinical trials as a potential therapeutic for treating autoimmune diseases. Other peptides and small-molecule inhibitors are critically evaluated for their lead-like characteristics and potential for progression into clinical development. Some small-molecule inhibitors with well-defined structure-activity relationships have been optimized for selective delivery to mitochondria, and these offer therapeutic potential for the treatment of cancers. This overview of KV 1.3 inhibitors and methodologies is designed to provide a good starting point for drug discovery to identify novel effective KV 1.3 modulators against this target in the future.
Assuntos
Venenos de Cnidários , Anêmonas-do-Mar , Animais , Química Farmacêutica , Humanos , Canal de Potássio Kv1.3 , Bloqueadores dos Canais de Potássio/farmacologiaRESUMO
The KV10.1 voltage-gated potassium channel is highly expressed in 70% of tumors, and thus represents a promising target for anticancer drug discovery. However, only a few ligands are known to inhibit KV10.1, and almost all also inhibit the very similar cardiac hERG channel, which can lead to undesirable side-effects. In the absence of the structure of the KV10.1-inhibitor complex, there remains the need for new strategies to identify selective KV10.1 inhibitors and to understand the binding modes of the known KV10.1 inhibitors. To investigate these binding modes in the central cavity of KV10.1, a unique approach was used that allows derivation and analysis of ligand-protein interactions from molecular dynamics trajectories through pharmacophore modeling. The final molecular dynamics-derived structure-based pharmacophore model for the simulated KV10.1-ligand complexes describes the necessary pharmacophore features for KV10.1 inhibition and is highly similar to the previously reported ligand-based hERG pharmacophore model used to explain the nonselectivity of KV10.1 pore blockers. Moreover, analysis of the molecular dynamics trajectories revealed disruption of the π-π network of aromatic residues F359, Y464, and F468 of KV10.1, which has been reported to be important for binding of various ligands for both KV10.1 and hERG channels. These data indicate that targeting the KV10.1 channel pore is also likely to result in undesired hERG inhibition, and other potential binding sites should be explored to develop true KV10.1-selective inhibitors as new anticancer agents.
Assuntos
Canais de Potássio Éter-A-Go-Go/antagonistas & inibidores , Canais de Potássio Éter-A-Go-Go/química , Bloqueadores dos Canais de Potássio/farmacologia , Antineoplásicos/química , Antineoplásicos/farmacologia , Sítios de Ligação , Descoberta de Drogas , Canais de Potássio Éter-A-Go-Go/genética , Canais de Potássio Éter-A-Go-Go/metabolismo , Células HEK293 , Humanos , Ligantes , Simulação de Dinâmica Molecular , Neoplasias/tratamento farmacológicoRESUMO
The voltage-gated potassium channel Kv1.3 is involved in multiple autoimmune diseases, such as multiple sclerosis, rheumatoid arthritis, diabetes mellitus type 1 and psoriasis. In many auto-immune diseases better treatment options are desired as existing therapies are often ineffective or become less effective over time, for which Kv1.3 inhibitors arise as promising candidates. In this study, five compounds were selected based on a 3D similarity searching methodology and subsequently screened ex vivo on the Kv1.3 channel. The screening resulted in two compounds inhibiting the Kv1.3 channel, of which TVS-12 was the most potent compound, while TVS-06 -although less potent- showed an excellent selectivity for Kv1.3. For both compounds the mechanism of action was investigated by an electrophysiological characterization on the Kv1.3 channel and three Kv1.3 mutants, designed to resemble the pore region of Kv1.2 channels. Structurally, the presence of a benzene ring and/or an oxane ring seems to cause a better interaction with the Kv1.3 channel, resulting in a 20-fold higher potency for TVS-12.
Assuntos
Desenho de Fármacos , Canal de Potássio Kv1.3/antagonistas & inibidores , Bloqueadores dos Canais de Potássio/farmacologia , Animais , Relação Dose-Resposta a Droga , Feminino , Canal de Potássio Kv1.3/metabolismo , Estrutura Molecular , Bloqueadores dos Canais de Potássio/síntese química , Bloqueadores dos Canais de Potássio/química , Relação Estrutura-Atividade , Xenopus laevisRESUMO
In the original publication [...].
RESUMO
A new series of dual low nanomolar benzothiazole inhibitors of bacterial DNA gyrase and topoisomerase IV were developed. The resulting compounds show excellent broad-spectrum antibacterial activities against Gram-positive Enterococcus faecalis, Enterococcus faecium and multidrug resistant (MDR) Staphylococcus aureus strains [best compound minimal inhibitory concentrations (MICs): range, <0.03125-0.25 µg/mL] and against the Gram-negatives Acinetobacter baumannii and Klebsiella pneumoniae (best compound MICs: range, 1-4 µg/mL). Lead compound 7a was identified with favorable solubility and plasma protein binding, good metabolic stability, selectivity for bacterial topoisomerases, and no toxicity issues. The crystal structure of 7a in complex with Pseudomonas aeruginosa GyrB24 revealed its binding mode at the ATP-binding site. Expanded profiling of 7a and 7h showed potent antibacterial activity against over 100 MDR and non-MDR strains of A. baumannii and several other Gram-positive and Gram-negative strains. Ultimately, in vivo efficacy of 7a in a mouse model of vancomycin-intermediate S. aureus thigh infection was also demonstrated.
Assuntos
Staphylococcus aureus , Staphylococcus aureus Resistente à Vancomicina , Animais , Camundongos , Staphylococcus aureus/metabolismo , Antibacterianos/farmacologia , Antibacterianos/uso terapêutico , Antibacterianos/química , DNA Girase/metabolismo , DNA Topoisomerase IV , Testes de Sensibilidade MicrobianaRESUMO
Expression of the voltage-gated potassium channel KV10.1 (Eag1) has been detected in over 70% of human cancers, making the channel a promising new target for new anticancer drug discovery. A new structural class of KV10.1 inhibitors was prepared by structural optimisation and exploration of the structure-activity relationship of the previously published hit compound ZVS-08 (1) and its optimised analogue 2. The potency and selectivity of the new inhibitors between KV10.1 and hERG were investigated using whole-cell patch-clamp experiments. We obtained two new optimised KV10.1 inhibitors, 17a and 18b, with improved nanomolar IC50 values of 568 nM and 214 nM, respectively. Compound 17a exhibited better ratio between IC50 values for hEAG1 and hERG than previously published diarylamine inhibitors. Compounds 17a and 18b moderately inhibited the growth of the KV10.1-expressing cell line MCF-7 in two independent assays. In addition, 17a and 18b also inhibited the growth of hERG-expressing Panc-1 cells with higher potency compared with MCF-7 cells. The main obstacle for newly developed diarylamine KV10.1 inhibitors remains the selectivity toward the hERG channel, which needs to be addressed with targeted drug design strategies in the future.
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The voltage-gated potassium channel KV1.3 has been recognized as a tumor marker and represents a promising new target for the discovery of new anticancer drugs. We designed a novel structural class of KV1.3 inhibitors through structural optimization of benzamide-based hit compounds and structure-activity relationship studies. The potency and selectivity of the new KV1.3 inhibitors were investigated using whole-cell patch- and voltage-clamp experiments. 2D and 3D cell models were used to determine antiproliferative activity. Structural optimization resulted in the most potent and selective KV1.3 inhibitor 44 in the series with an IC50 value of 470 nM in oocytes and 950 nM in Ltk- cells. KV1.3 inhibitor 4 induced significant apoptosis in Colo-357 spheroids, while 14, 37, 43, and 44 significantly inhibited Panc-1 proliferation.
RESUMO
(1) Background: The voltage-gated potassium channel KV10.1 (Eag1) is considered a near- universal tumour marker and represents a promising new target for the discovery of novel anticancer drugs. (2) Methods: We utilized the ligand-based drug discovery methodology using 3D pharmacophore modelling and medicinal chemistry approaches to prepare a novel structural class of KV10.1 inhibitors. Whole-cell patch clamp experiments were used to investigate potency, selectivity, kinetics and mode of inhibition. Anticancer activity was determined using 2D and 3D cell-based models. (3) Results: The virtual screening hit compound ZVS-08 discovered by 3D pharmacophore modelling exhibited an IC50 value of 3.70 µM against KV10.1 and inhibited the channel in a voltage-dependent manner consistent with the action of a gating modifier. Structural optimization resulted in the most potent KV10.1 inhibitor of the series with an IC50 value of 740 nM, which was potent on the MCF-7 cell line expressing high KV10.1 levels and low hERG levels, induced significant apoptosis in tumour spheroids of Colo-357 cells and was not mutagenic. (4) Conclusions: Computational ligand-based drug design methods can be successful in the discovery of new potent KV10.1 inhibitors. The main problem in the field of KV10.1 inhibitors remains selectivity against the hERG channel, which needs to be addressed in the future also with target-based drug design methods.
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Benzo[d]thiazole is widely used in synthetic and medicinal chemistry, and it is a component of many compounds and drugs that have several different bioactivities. Herein, we describe an elegant pathway for synthesis of methyl 4- and 5-hydroxy-2-amino-benzo[d]thiazole-6-carboxylates as building blocks that can be substituted at four different positions on the bicycle and thus offer the possibility to thoroughly explore the chemical space around the molecule studied as a ligand for the chosen target. A series of 12 new compounds was prepared using the described methods and Williamson ether synthesis.