Phytochemical Composition, Anti-Inflammatory Property, and Anti-Atopic Effect of Chaetomorpha linum Extract.

Utilizing plant-based resources, particularly their by-products, aligns with sustainability principles and circular bioeconomy, contributing to environmental preservation. The therapeutic potential of plant extracts is garnering increasing interest, and this study aimed to demonstrate promising outcomes from an extract obtained from an underutilized plant waste. Chaetomorpha linum, an invasive macroalga found in the Orbetello Lagoon, thrives in eutrophic conditions, forming persistent mats covering approximately 400 hectares since 2005. The biomass of C. linum undergoes mechanical harvesting and is treated as waste, requiring significant human efforts and economic resources-A critical concern for municipalities. Despite posing challenges to local ecosystems, the study identified C. linum as a natural source of bioactive metabolites. Phytochemical characterization revealed lipids, amino acids, and other compounds with potential anti-inflammatory activity in C. linum extract. In vitro assays with LPS-stimulated RAW 264.7 and TNF-α/IFN-γ-stimulated HaCaT cells showed the extract inhibited reactive oxygen species (ROS), nitric oxide (NO), and prostaglandin E2 (PGE2) productions, and reduced inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) expressions via NF-κB nuclear translocation, in RAW 264.7 cells. It also reduced chemokines (TARC/CCL17, RANTES/CCL5, MCP-1/CCL2, and IL-8) and the cytokine IL-1ß production in HaCaT cells, suggesting potential as a therapeutic candidate for chronic diseases like atopic dermatitis. Finally, in silico studies indicated palmitic acid as a significant contributor to the observed effect. This research not only uncovered the untapped potential of C. linum but also laid the foundation for its integration into the circular bioeconomy, promoting sustainable practices, and innovative applications across various industries.

A Drug Discovery Approach to a Reveal Novel Antioxidant Natural Source: The Case of Chestnut Burr Biomass.

Currently, many environmental and energy-related problems are threatening the future of our planet. In October 2022, the Worldmeter recorded the world population as 7.9 billion people, estimating that there will be an increase of 2 billion by 2057. The rapid growth of the population and the continuous increase in needs are causing worrying conditions, such as pollution, climate change, global warming, waste disposal, and natural resource reduction. Looking for novel and innovative methods to overcome these global troubles is a must for our common welfare. The circular bioeconomy represents a promising strategy to alleviate the current conditions using biomass-like natural wastes to replace commercial products that have a negative effect on our ecological footprint. Applying the circular bioeconomy concept, we propose an integrated in silico and in vitro approach to identify antioxidant bioactive compounds extracted from chestnut burrs (an agroforest waste) and their potential biological targets. Our study provides a novel and robust strategy developed within the circular bioeconomy concept aimed at target and drug discovery for a wide range of diseases. Our study could open new frontiers in the circular bioeconomy related to target and drug discovery, offering new ideas for sustainable scientific research aimed at identifying novel therapeutical strategies.

Dynamin-independent CaV1.2 and KCa1.1 channels regulation and vascular tone modulation by the mitochondrial fission inhibitors dynasore and dyngo-4a.

A role for mitochondrial fission in vascular contraction has been proposed based on the vasorelaxant activity of the dynamin (and mitochondrial fission) inhibitors mdivi-1 and dynasore. However, mdivi-1 is capable to inhibit Ba2+ currents through CaV1.2 channels (IBa1.2), stimulate KCa1.1 channel currents (IKCa1.1), and modulate pathways key to the maintenance of vessel active tone in a dynamin-independent manner. Using a multidisciplinary approach, the present study demonstrates that dynasore, like mdivi-1, is a bi-functional vasodilator, blocking IBa1.2 and stimulating IKCa1.1 in rat tail artery myocytes, as well as promoting relaxation of rat aorta rings pre-contracted by either high K+ or phenylephrine. Conversely, its analogue dyngo-4a, though inhibiting mitochondrial fission triggered by phenylephrine and stimulating IKCa1.1, did not affect IBa1.2 but potentiated both high K+- and phenylephrine-induced contractions. Docking and molecular dynamics simulations identified the molecular basis supporting the different activity of dynasore and dyngo-4a at CaV1.2 and KCa1.1 channels. Mito-tempol only partially counteracted the effects of dynasore and dyngo-4a on phenylephrine-induced tone. In conclusion, the present data, along with previous observations (Ahmed et al., 2022) rise caution for the use of dynasore, mdivi-1, and dyngo-4a as tools to investigate the role of mitochondrial fission in vascular contraction: to this end, a selective dynamin inhibitor and/or a different experimental approach are needed.

Artificial intelligence-driven identification of morin analogues acting as CaV1.2 channel blockers: Synthesis and biological evaluation.

Morin is a vasorelaxant flavonoid, whose activity is ascribable to CaV1.2 channel blockade that, however, is weak as compared to that of clinically used therapeutic agents. A conventional strategy to circumvent this drawback is to synthesize new derivatives differently decorated and, in this context, morin-derivatives able to interact with CaV1.2 channels were found by employing the potential of PLATO in target fishing and reverse screening. Three different derivatives (5a-c) were selected as promising tools, synthesized, and investigated in in vitro functional studies using rat aorta rings and rat tail artery myocytes. 5a-c were found more effective vasorelaxant agents than the naturally occurring parent compound and antagonized both electro- and pharmaco-mechanical coupling in an endothelium-independent manner. 5a, the series' most potent, reduced also Ca2+ mobilization from intracellular store sites. Furthermore, 5a≈5c > 5b inhibited Ba2+ current through CaV1.2 channels. However, compound 5a caused also a concentration-dependent inhibition of KCa1.1 channel currents.

Targeting neuronal calcium channels and GSK3ß for Alzheimer's disease with naturally-inspired Diels-Alder adducts.

The complexity of neurodegenerative diseases, among which Alzheimer's disease plays a pivotal role, poses one of the tough therapeutic challenges of present time. In this perspective, a multitarget approach appears as a promising strategy to simultaneously interfere with different defective pathways. In this paper, a structural simplification plan was performed on our previously reported multipotent polycyclic compounds, in order to obtain a simpler pharmacophoric central core with improved pharmacokinetic properties, while maintaining the modulating activity on neuronal calcium channels and glycogen synthase kinase 3-beta (GSK-3ß), as validated targets to combat Alzheimer's disease. The molecular pruning approach applied here led to tetrahydroisoindole-dione (1), tetrahydromethanoisoindole-dione (2) and tetrahydroepoxyisoindole-dione (3) structures, easily affordable by Diels-Alder cycloaddition. Preliminary data indicated structure 3 as the most appropriate, thus a SAR study was performed by introducing different substituents, selected on the basis of the commercial availability of the furan derivatives required for the synthetic procedure. The results indicated compound 10 as a promising, structurally atypical, safe and BBB-penetrating Cav modulator, inhibiting both L- and N-calcium channels, likely responsible for the Ca2+ overload observed in Alzheimer's disease. In a multitarget perspective, compound 11 appeared as an effective prototype, endowed with improved Cav inhibitory activity, with respect to the reference drug nifedipine, and encouraging modulating activity on GSK-3ß.

Novel Labdane Diterpenes-Based Synthetic Derivatives: Identification of a Bifunctional Vasodilator That Inhibits CaV1.2 and Stimulates KCa1.1 Channels.

Sesquiterpenes such as leucodin and the labdane-type diterpene manool are natural compounds endowed with remarkably in vitro vasorelaxant and in vivo hypotensive activities. Given their structural similarity with the sesquiterpene lactone (+)-sclareolide, this molecule was selected as a scaffold to develop novel vasoactive agents. Functional, electrophysiology, and molecular dynamics studies were performed. The opening of the five-member lactone ring in the (+)-sclareolide provided a series of labdane-based small molecules, promoting a significant in vitro vasorelaxant effect. Electrophysiology data identified 7 as a CaV1.2 channel blocker and a KCa1.1 channel stimulator. These activities were also confirmed in the intact vascular tissue. The significant antagonism caused by the CaV1.2 channel agonist Bay K 8644 suggested that 7 might interact with the dihydropyridine binding site. Docking and molecular dynamic simulations provided the molecular basis of the CaV1.2 channel blockade and KCa1.1 channel stimulation produced by 7. Finally, 7 reduced coronary perfusion pressure and heart rate, while prolonging conduction and refractoriness of the atrioventricular node, likely because of its Ca2+ antagonism. Taken together, these data indicate that the labdane scaffold represents a valuable starting point for the development of new vasorelaxant agents endowed with negative chronotropic properties and targeting key pathways involved in the pathophysiology of hypertension and ischemic cardiomyopathy.

The drp-1-mediated mitochondrial fission inhibitor mdivi-1 impacts the function of ion channels and pathways underpinning vascular smooth muscle tone.

Mdivi-1 is widely used as a pharmacological tool to inhibit dynamin-related protein-1-mediated mitochondrial fission. Whether this compound may interact directly or indirectly with ion channels or cellular pathways fundamental for the regulation of vascular smooth muscle tone remains unknown. The present study aimed to assess the effect of mdivi-1 on CaV1.2 and KCa1.1 channels, both in vitro and in silico as well as on the mechanical activity of rat aorta rings. Mdivi-1 was an effective CaV1.2 channel blocker, docking in a CaV1.2 channel antagonist binding region, stimulated KCa1.1 channel current, binding to a sensing region common to other stimulators, and possibly inhibited the Rho-kinase pathway. These effects contributed to its vasorelaxant activity observed in rings stimulated with high KCl, phenylephrine, or NaF. Neither structurally different dynamin inhibitors nor a stimulator affected the Ca2+ antagonistic and vasorelaxant activities of the compound. However, mito-tempol reduced its vasorelaxant potency towards phenylephrine. Finally, mdivi-1 antagonized mitochondrial fission triggered by phenylephrine. In conclusion, mdivi-1 is an effective in vitro vasorelaxant agent at concentrations routinely employed to block dynamin-related protein-1. Ion channels and pathways key to the maintenance of vessel active tone are involved in this mechanism. These yet undiscovered off-target effects raise caution for the interpretation of mitochondrial fission signalling.

Pharmacological and In Silico Analysis of Oat Avenanthramides as EGFR Inhibitors: Effects on EGF-Induced Lung Cancer Cell Growth and Migration.

Avena sativa L. is a wholegrain cereal and an important edible crop. Oats possesses high nutritional and health promoting values and contains high levels of bioactive compounds, including a group of phenolic amides, named avenanthramides (Avns), exerting antioxidant, anti-inflammatory, and anticancer activities. Epidermal growth factor receptor (EGFR) represents one of the most known oncogenes and it is frequently up-regulated or mutated in human cancers. The oncogenic effects of EGFR include enhanced cell growth, angiogenesis, and metastasis, and down-regulation or inhibition of EGFR signaling has therapeutic benefit. Front-line EGFR tyrosine kinase inhibitor therapy is the standard therapy for patients with EGFR-mutated lung cancer. However, the clinical effects of EGFR inhibition may be lost after a few months of treatment due to the onset of resistance. Here, we showed the anticancer activity of Avns, focusing on EGFR activation and signaling pathway. Lung cancer cellular models have been used to evaluate the activity of Avns on tumor growth, migration, EMT, and anoikis induced by EGF. In addition, docking and molecular dynamics simulations showed that the Avns bind with high affinity to a region in the vicinity of αC-helix and the DGF motif of EGFR, jeopardizing the target biological function. Altogether, our results reveal a new pharmacological activity of Avns as EGFR tyrosine kinase inhibitors.

Vietnamese Dalbergia tonkinensis: A Promising Source of Mono- and Bifunctional Vasodilators.

Hypertension is a risk factor for cardiovascular diseases, which are the main cause of morbidity and mortality in the world. In the search for new molecules capable of targeting KCa1.1 and CaV1.2 channels, the expression of which is altered in hypertension, the in vitro vascular effects of a series of flavonoids extracted from the heartwoods, roots, and leaves of Dalbergia tonkinensis Prain, widely used in traditional medicine, were assessed. Rat aorta rings, tail artery myocytes, and docking and molecular dynamics simulations were used to analyse their effect on these channels. Formononetin, orobol, pinocembrin, and biochanin A showed a marked myorelaxant activity, particularly in rings stimulated by moderate rather than high KCl concentrations. Ba2+ currents through CaV1.2 channels (IBa1.2) were blocked in a concentration-dependent manner by sativanone, 3'-O-methylviolanone, pinocembrin, and biochanin A, while it was stimulated by ambocin. Sativanone, dalsissooside, and eriodictyol inhibited, while tectorigenin 7-O-[ß-D-apiofuranosyl-(1→6)-ß-D-glucopyranoside], ambocin, butin, and biochanin A increased IKCa1.1. In silico analyses showed that biochanin A, sativanone, and pinocembrin bound with high affinity in target-sensing regions of both channels, providing insight into their potential mechanism of action. In conclusion, Dalbergia tonkinensis is a valuable source of mono- and bifunctional, vasoactive scaffolds for the development of novel antihypertensive drugs.

In Silico Multi-Target Approach Revealed Potential Lead Compounds as Scaffold for the Synthesis of Chemical Analogues Targeting SARS-CoV-2.

Severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2) causes coronavirus disease 2019 (COVID-19), an infectious disease that spreads rapidly in humans. In March 2020, the World Health Organization (WHO) declared a COVID-19 pandemic. Identifying a multi-target-directed ligand approach would open up new opportunities for drug discovery to combat COVID-19. The aim of this work was to perform a virtual screening of an exclusive chemical library of about 1700 molecules containing both pharmacologically active compounds and synthetic intermediates to propose potential protein inhibitors for use against SARS-CoV-2. In silico analysis showed that our compounds triggered an interaction network with key residues of the SARS-CoV-2 spike protein (S-protein), blocking trimer formation and interaction with the human receptor hACE2, as well as with the main 3C-like protease (3CLpro), inhibiting their biological function. Our data may represent a step forward in the search for potential new chemotherapeutic agents for the treatment of COVID-19.

Functional, electrophysiology, and molecular dynamics analysis of quercetin-induced contraction of rat vascular musculature.

Quercetin, a flavonoid abundantly present in the Mediterranean diet, is considered a vasodilator despite its recognized capability to stimulate vascular CaV1.2 channel current (ICa1.2). The present study was undertaken to assess its possible vasocontractile activity. Functional and electrophysiology experiments were performed in vitro on rat aorta rings and tail artery myocytes along with an in-depth molecular modelling analysis. The CaV1.2 channel stimulator (S)-(-)-methyl-1,4-dihydro-2,6-dimethyl-3-nitro-4-(2-trifluoromethylphenyl) pyridine-5-carboxylate (Bay K 8644) was used as reference compound. Quercetin and Bay K 8644 caused a significant leftward shift of KCl concentration-response curve. Neither agent affected basal muscle tone, though in rings pre-treated with thapsigargin or 15 mM KCl they caused a strong, concentration-dependent contraction. Both quercetin and Bay K 8644 potentiated the response to Ca2+ in weakly depolarised rings. At high KCl concentrations, however, quercetin caused vasorelaxation. While Bay K 8644 stimulated ICa1.2, this effect being sustained with time, quercetin-induced stimulation was transient, although the molecule in solution underwent only marginal oxidation. Quercetin transient stimulation was not affected by pre-treatment with isoprenaline, sodium nitroprusside, or dephostatin; however, it converted to a sustained one in myocytes pre-incubated with Gö6976. Classical molecular dynamics simulations revealed that quercetin and Bay K 8644 formed hydrogen bonds with target sensing residues of CaV1.2 channel favouring the inactivated conformation. In conclusion, quercetin-induced stimulation of ICa1.2 promoted vasocontraction when Ca2+ buffering function of sarcoplasmic reticulum was impaired and/or smooth muscle cell membrane was moderately depolarised, as it may occur under certain pathological conditions.

Structural Bioinformatic Survey of Protein-Small Molecule Interfaces Delineates the Role of Glycine in Surface Pocket Formation.

With a structural bioinformatic approach, we have explored amino acid compositions at PISA defined interfaces between small molecules and proteins that are contained in an optimized subset of 11,351 PDB files. The use of a series of restrictions, to prevent redundancy and biases from interactions between amino acids with charged side chains and ions, yielded a final data set of 45,230 protein-small molecule interfaces. We have compared occurrences of natural amino acids in surface exposed regions and binding sites for all the proteins of our data set. From our structural bioinformatic survey, the most relevant signal arose from the unexpected Gly abundance at enzyme catalytic sites. This finding suggested that Gly must have a fundamental role in stabilizing concave protein surface moieties. Subsequently, we have tried to predict the effect of in silico Gly mutations in hen egg white lysozyme to optimize those conditions that can reshape the protein surface with the appearance of new pockets. Replacing amino acids having bulky side chains with Gly in specific protein regions seems a feasible way for designing proteins with additional surface pockets, which can alter protein surface dynamics, therefore, representing controllable switches for protein activity.

Flavonoids and hERG channels: Friends or foes?

The cardiac action potential is regulated by several ion channels. Drugs capable to block these channels, in particular the human ether-à-go-go-related gene (hERG) channel, also known as KV11.1 channel, may lead to a potentially lethal ventricular tachyarrhythmia called "Torsades de Pointes". Thus, evaluation of the hERG channel off-target activity of novel chemical entities is nowadays required to safeguard patients as well as to avoid attrition in drug development. Flavonoids, a large class of natural compounds abundantly present in food, beverages, herbal medicines, and dietary food supplements, generally escape this assessment, though consumed in consistent amounts. Continuously growing evidence indicates that these compounds may interact with the hERG channel and block it. The present review, by examining numerous studies, summarizes the state-of-the-art in this field, describing the most significant examples of direct and indirect inhibition of the hERG channel current operated by flavonoids. A description of the molecular interactions between a few of these natural molecules and the Rattus norvegicus channel protein, achieved by an in silico approach, is also presented.

A multitarget semi-synthetic derivative of the flavonoid morin with improved in vitro vasorelaxant activity: Role of CaV1.2 and KCa1.1 channels.

CaV1.2 channels play a fundamental role in the regulation of vascular smooth muscle tone. The aim of the present study was to synthesize morin derivatives bearing the nitrophenyl moiety of dihydropyridine Ca2+ antagonists to increase the flavonoid vasorelaxant activity. The effects of morin and its derivatives were assessed on CaV1.2 and KCa1.1 channels, both in vitro and in silico, as well as on the contractile responses of rat aorta rings. All compounds were effective CaV1.2 channel blockers, positioning in the α1C subunit region where standard blockers bind. Among the four newly synthesized morin derivatives, the penta-acetylated morin-1 was the most efficacious Ca2+ antagonist, presenting a vasorelaxant profile superior to that of the parent compound and, contrary to morin, antagonized also the release of Ca2+ from the sarcoplasmic reticulum; surprisingly, it also stimulated KCa1.1 channel current. Computational analysis demonstrated that morin-1 bound close to the KCa1.1 channel S6 segment. In conclusion, these findings open a new avenue for the synthesis of valuable multi-functional, vasorelaxant morin derivatives capable to target several pathways underpinning the pathogenesis of hypertension.

Multifaceted activity of polyciclic MDR revertant agents in drug-resistant leukemic cells: Role of the spacer.

A small library of derivatives carrying a polycyclic scaffold recently identified by us as a new privileged structure in medicinal chemistry was designed and synthesized, aiming at obtaining potent MDR reverting agents also endowed with antitumor properties. In particular, as a follow-up of our previous studies, attention was focused on the role of the spacer connecting the polycyclic core with a properly selected nitrogen-containing group. A relevant increase in reverting potency was observed, going from the previously employed but-2-ynyl- to a pent-3-ynylamino moiety, as in compounds 3d and 3e, while the introduction of a triazole ring proved to differently impact on the activity of the compounds. The docking results supported the data obtained by biological tests, showing, for the most active compounds, the ability to establish specific bonds with P-glycoprotein. Moreover, a multifaceted anticancer profile and dual in vitro activity was observed for all compounds, showing both revertant and antitumor effects on leukemic cells. In this respect, 3c emerged as a "triple-target" agent, endowed with a relevant reverting potency, a considerable antiproliferative activity and a collateral sensitivity profile.

Design, synthesis and pharmacological evaluation of ester-based quercetin derivatives as selective vascular KCa1.1 channel stimulators.

Quercetin represents one of the most studied dietary flavonoids; it exerts a panel of pharmacological activities particularly on the cardiovascular system. Stimulation of vascular KCa1.1 channels contributes to its vasorelaxant activity, which is, however, counteracted in part by its concomitant stimulation of CaV1.2 channels. Therefore, several quercetin hybrid derivatives were designed and synthesized to produce a more selective KCa1.1 channel stimulator, then assessed both in silico and in vitro. All the derivatives interacted with the KCa1.1 channel with similar binding energy values. Among the selected derivatives, 1E was a weak vasodilator, though displaying an interesting CaV1.2 channel blocking activity. The lipoyl derivatives 1F and 3F, though showing pharmacological and electrophysiological features similar to those of quercetin, seemed to be more effective as KCa1.1 channel stimulators as compared to the parent compound. The strategy pursued demonstrated how different chemical substituents on the quercetin core can change/invert its effect on CaV1.2 channels or enhance its KCa1.1 channel stimulatory activity, thus opening new avenues for the synthesis of efficacious vasorelaxant quercetin hybrids.

An integrated drug repurposing strategy for the rapid identification of potential SARS-CoV-2 viral inhibitors.

The Coronavirus disease 2019 (COVID-19) is an infectious disease caused by the severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2). The virus has rapidly spread in humans, causing the ongoing Coronavirus pandemic. Recent studies have shown that, similarly to SARS-CoV, SARS-CoV-2 utilises the Spike glycoprotein on the envelope to recognise and bind the human receptor ACE2. This event initiates the fusion of viral and host cell membranes and then the viral entry into the host cell. Despite several ongoing clinical studies, there are currently no approved vaccines or drugs that specifically target SARS-CoV-2. Until an effective vaccine is available, repurposing FDA approved drugs could significantly shorten the time and reduce the cost compared to de novo drug discovery. In this study we attempted to overcome the limitation of in silico virtual screening by applying a robust in silico drug repurposing strategy. We combined and integrated docking simulations, with molecular dynamics (MD), Supervised MD (SuMD) and Steered MD (SMD) simulations to identify a Spike protein - ACE2 interaction inhibitor. Our data showed that Simeprevir and Lumacaftor bind the receptor-binding domain of the Spike protein with high affinity and prevent ACE2 interaction.

ACE2 gene variants may underlie interindividual variability and susceptibility to COVID-19 in the Italian population.

In December 2019, an initial cluster of interstitial bilateral pneumonia emerged in Wuhan, China. A human-to-human transmission was assumed and a previously unrecognized entity, termed coronavirus disease-19 (COVID-19) due to a novel coronavirus (SARS-CoV-2) was described. The infection has rapidly spread out all over the world and Italy has been the first European country experiencing the endemic wave with unexpected clinical severity in comparison with Asian countries. It has been shown that SARS-CoV-2 utilizes angiotensin converting enzyme 2 (ACE2) as host receptor and host proteases for cell surface binding and internalization. Thus, a predisposing genetic background can give reason for interindividual disease susceptibility and/or severity. Taking advantage of the Network of Italian Genomes (NIG), here we mined whole-exome sequencing data of 6930 Italian control individuals from five different centers looking for ACE2 variants. A number of variants with a potential impact on protein stability were identified. Among these, three more common missense changes, p.(Asn720Asp), p.(Lys26Arg), and p.(Gly211Arg) were predicted to interfere with protein structure and stabilization. Rare variants likely interfering with the internalization process, namely p.(Leu351Val) and p.(Pro389His), predicted to interfere with SARS-CoV-2 spike protein binding, were also observed. Comparison of ACE2 WES data between a cohort of 131 patients and 258 controls allowed identifying a statistically significant (P value < 0.029) higher allelic variability in controls compared with patients. These findings suggest that a predisposing genetic background may contribute to the observed interindividual clinical variability associated with COVID-19, allowing an evidence-based risk assessment leading to personalized preventive measures and therapeutic options.

A possible strategy to fight COVID-19: Interfering with spike glycoprotein trimerization.

The recent release of COVID-19 spike glycoprotein allows detailed analysis of the structural features that are required for stabilizing the infective form of its quaternary assembly. Trying to disassemble the trimeric structure of COVID-19 spike glycoprotein, we analyzed single protomer surfaces searching for concave moieties that are located at the three protomer-protomer interfaces. The presence of some druggable pockets at these interfaces suggested that some of the available drugs in Drug Bank could destabilize the quaternary spike glycoprotein formation by binding to these pockets, therefore interfering with COVID-19 life cycle. The approach we propose here can be an additional strategy to fight against the deadly virus. Ligands of COVID-19 spike glycoprotein that we have predicted in the present computational investigation, might be the basis for new experimental studies in vitro and in vivo.

Ritanserin blocks CaV1.2 channels in rat artery smooth muscles: electrophysiological, functional, and computational studies.

CaV1.2 channel blockers or 5-HT2 receptor antagonists constitute effective therapy for Raynaud's syndrome. A functional link between the inhibition of 5-HT2 receptors and CaV1.2 channel blockade in arterial smooth muscles has been hypothesized. Therefore, the effects of ritanserin, a nonselective 5-HT2 receptor antagonist, on vascular CaV1.2 channels were investigated through electrophysiological, functional, and computational studies. Ritanserin blocked CaV1.2 channel currents (ICa1.2) in a concentration-dependent manner (Kr = 3.61 µM); ICa1.2 inhibition was antagonized by Bay K 8644 and partially reverted upon washout. Conversely, the ritanserin analog ketanserin (100 µM) inhibited ICa1.2 by ~50%. Ritanserin concentration-dependently shifted the voltage dependence of the steady-state inactivation curve to more negative potentials (Ki = 1.58 µM) without affecting the slope of inactivation and the activation curve, and decreased ICa1.2 progressively during repetitive (1 Hz) step depolarizations (use-dependent block). The addition of ritanserin caused the contraction of single myocytes not yet dialyzed with the conventional method. Furthermore, in depolarized rings, ritanserin, and to a lesser extent, ketanserin, caused a concentration-dependent relaxation, which was antagonized by Bay K 8644. Ritanserin and ketanserin were docked at a region of the CaV1.2 α1C subunit nearby that of Bay K 8644; however, only ritanserin and Bay K 8644 formed a hydrogen bond with key residue Tyr-1489. In conclusion, ritanserin caused in vitro vasodilation, accomplished through the blockade of CaV1.2 channels, which was achieved preferentially in the inactivated and/or resting state of the channel. This novel activity encourages the development of ritanserin derivatives for their potential use in the treatment of Raynaud's syndrome.