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Introduction: T-type calcium channels are attractive targets for potential treatment of epilepsy inflammatory or neuropathic pain, insomnia, Parkinson's disease, and cancer. Three isoforms having different biophysical functions are expressed in peripheral and central nerve. Since the withdrawal of mibefradil, the first compound marketed for selective T-type calcium channel blockade, extensive efforts have been made to identify more selective T-type calcium channel blockers., Areas Covered: This review covers the 43 patents describing 'organic small molecules as T-type calcium channel blockers'-published since 2012. The most recent similar patent review was published in 2011. Information from a recent review article and relevant research papers has been included, as well as biological data and clinical trial results where available., Expert Opinion: Triazinone derivatives, carbazole compounds, and aryl triazole/imidazole amide derivatives display potent blockade activity α1H, α1G, and pan T-type calcium channel subtypes, respectively, though the specificity of the letter is still unsatisfactory. Nonetheless, improvements seen in the efficacy of compounds targeting α1H T-type calcium channels indicate significant progress. Ongoing clinical trials are for the candidates Z944 (Phase II) and ACT-709478 (Phase II) appear promising. These studies may lead to a new generation of inhibitors with higher selectivity, improved physicochemical properties, and reduced side effects.

The treatment of neuropathic pain is one of the urgent unmet medical needs and T-type calcium channels are promising therapeutic targets for neuropathic pain. Several potent T-type channel inhibitors showed promising in vivo efficacy in neuropathic pain animal models and are being investigated in clinical trials. Herein we report development of novel pyrrolidine-based T-type calcium channel inhibitors by pharmacophore mapping and structural hybridisation followed by evaluation of their Ca v 3.1 and Ca v 3.2 channel inhibitory activities. Among potent inhibitors against both Ca v 3.1 and Ca v 3.2 channels, a promising compound 20n based on in vitro ADME properties displayed satisfactory plasma and brain exposure in rats according to in vivo pharmacokinetic studies. We further demonstrated that 20n effectively improved the symptoms of neuropathic pain in both SNL and STZ neuropathic pain animal models, suggesting modulation of T-type calcium channels can be a promising therapeutic strategy for the treatment of neuropathic pain.

α-Conotoxins exhibiting analgesic activity, such as Vc1.1, have been shown to inhibit α9α10 nicotinic acetylcholine receptors (nAChRs) and GABA B -receptor (GABA B R) coupled N-type (Ca V 2.2) calcium channels. Here, we report two Vc1.1 variants, Vc1.1[N9R] and benzoyl-Vc1.1[N9R], that selectively inhibit Ca V 2.2 channels via GABA B R activation but exhibit reduced inhibitory activity at α9α10 and other neuronal nAChR subtypes compared with Vc1.1. Surprisingly, the analgesic activity of Vc1.1[N9R] and benzoyl-Vc1.1[N9R] was more potent than that of Vc1.1 when tested in partial sciatic nerve ligation injury and chronic constriction injury models. Vc1.1[N9R] and benzoyl-Vc1.1[N9R] exhibited either similar or tenfold higher activity of GABA B R-mediated Ca V 2.2 inhibition but no activity at Ca V 2.2 alone; however, the mechanism of increased analgesic activity is unknown. The effects on analgesic activity and α9α10 nAChR of other Vc1.1 variations at position 9 and the N-terminus were also determined. Our findings provide new insights for designing potent inhibitors for GABA B R-coupled N-type (Ca V 2.2) calcium channels.

Parkinson disease (PD) is a progressive neurological disease caused by selective degeneration of dopaminergic (DA) neurons in the substantia nigra. Although most cases of PD are sporadic cases, familial PD provides a versatile research model for basic mechanistic insights into the pathogenesis of PD. In this study, we generated DA neurons from PARK2 patient-specific, isogenic PARK2 null and PARK6 patient-specific induced pluripotent stem cells and found that these neurons exhibited more apoptosis and greater susceptibility to rotenone-induced mitochondrial stress. From phenotypic screening with an FDA-approved drug library, one voltage-gated calcium channel antagonist, benidipine, was found to suppress rotenone-induced apoptosis. Furthermore, we demonstrated the dysregulation of calcium homeostasis and increased susceptibility to rotenone-induced stress in PD, which is prevented by T-type calcium channel knockdown or antagonists. These findings suggest that calcium homeostasis in DA neurons might be a useful target for developing new drugs for PD patients., (Copyright © 2018 The Author(s). Published by Elsevier Inc. All rights reserved.)

Venomous animals produce toxins that inhibit ion channels with high affinity. These small peptide inhibitors are used in the characterization of ion channels structurally as well as pharmacologically. So, identification of these toxins is an important task. In this study, based on the pseudo amino acid (PseAA) composition and feature selection method, the random forest algorithm was used for predicting three different groups of ion channel inhibitors. The prediction results indicated that our algorithm achieved the sensitivity of 60.00% for calcium channel inhibitor, 71.90% for potassium channel inhibitor and 86.80% for sodium channel inhibitor when evaluated by the jackknife test. In addition, for comparing with other algorithms, this algorithm was used to predict the dataset with 343 ion channel inhibitors, and the higher predictive success rates than the previous algorithms were obtained by our algorithm., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

The present study demonstrated the systematic adaptation of quality by design-integrated approach for the development of novel nanostructured lipid carrier (NLC) of an anti-hypertensive drug isradipine (ISD) to address the inherent challenges such as low solubility and low oral bioavailability. Plackett-Burman design was used for preliminary screening of significant process and formulation variables (p <0.05), which were further processed using Box-Behnken design for the attainment of optimization goal that is, mean particle size (85.7 ± 7.3 nm), drug entrapment efficiency (87.4 ± 3.29%), and in vitro drug release characteristics (92.89 ± 5.47%). The optimized ISD-NLC formulation also demonstrated well-dispersed uniform-shaped particles (polydispersity index 0.207 ± 0.029), high gastrointestinal fluid stability (zeta potential -10.17 ± 0.59 mV), and higher in vitro gut permeation (21.69 ± 2.38 μg/cm 2 of ISD-NLC as compared to 11.23 ± 1.74 μg/cm 2 in ISD suspension). Furthermore, lipolysis studies were performed for the purpose of in vivo fate, and significantly higher drug content of ISD from ISD-NLC in aqueous phase was found (72.34 ± 4.62%) as compared to drug suspension (3.01 ± 0.91%). Relative bioavailability of ISD-NLC and ISD suspension was increased by 4.2-fold and 1.78-fold in the absence and presence of cycloheximide which is a lymphatic uptake inhibitor revealing lymphatic uptake of ISD-NLC in bioavailability improvement. Hence, systematic adaptation of quality by design integrated approach improved gut permeation and potential solubilizaton fate (dynamic lipolysis) of ISD-NLC, which further improved the lymphatic uptake and biodistribution of drug thereby promisingits in vivo prospect and clinical efficacy., (Copyright © 2018 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.)

Preliminary results concerning the first asymmetric synthesis of highly functionalized 1-benzamido-1,4-dihydropyridine derivatives via the reaction of hydrazones with alkylidenemalononitriles in the presence of β-isocupreidine catalyst are reported. The moderate, but promising, enantioselectivity observed (40⁻54% ee), opens the door to a new area of research for the asymmetric construction of new chiral 1,4-dihydropyridine derivatives, whose enantioselective catalytic preparation are still very limited. Moreover, the use of hydrazones for the enantioselective construction of chiral 1,4-dihydropyridines has been overlooked in the literature so far. Therefore, our research represents a pivotal example in this field which remains still unexplored.

The pH-responsive intelligent drug release facility of hydrophobically modified chitosan nanoparticles (Chit NPs) (d = 5.2 ± 1.1 nm) was presented in the case of poorly water soluble Ca 2+ channel blocker nimodipine (NIMO) drug molecules. The adequate pH-sensitivity, i.e. the suitable drug carrier properties of the initial hydrophilic Chit were achieved by reductive amination of Chit with hexanal (C 6 -) and dodecanal (C 12 -) aldehydes. The successful modifications of the macromolecule were evidenced via FTIR measurements: the band appearing at 1412 cm -1 (CN stretching in aliphatic amines) in the cases of the hydrophobically modified Chit samples shows that the CN bond successfully formed between the Chit and the aldehydes. Hydrophobization of the polymer unambiguously led to lower water contents with lower intermolecular interactions in the prepared hydrogel matrix: the initial hydrophilic Chit has the highest water content (78.6 wt%) and the increasing hydrophobicity of the polymer resulted in decreasing water content (C 6 -chit.: 74.2 wt% and C 12 -chit.: 47.1 wt%). Furthermore, it was established that the length of the side chain of the aldehyde influences the pH-dependent solubility properties of the Chit. Transparent homogenous polymer solution was obtained at lower pH, while at higher pH the formation of polymer (nano)particles was determined and the corresponding cut-off pH values showed decreasing tendency with increasing hydrophobic feature (pH = 7.47, 6.73 and 2.49 for initial Chit, C 6 -chit and C 12 -chit, respectively). Next the poorly water soluble NIMO drug was encapsulated with the C 6 -chit with adequate pH-sensitive properties. The polymer-stabilized NIMO particles with 10 wt% NIMO content resulted in stable dispersion in aqueous phase, the formation of polymer shell increased in the water solubility/dispersibility of the initial hydrophobic drug. According to the drug release experiments, we clearly confirmed that the encapsulated low crystallinity NIMO drug remained closed in the polymer NPs at normal tissue pH (pH = 7.4, PBS buffer, physiological condition) but at pH < 6.5 which is typical for seriously ischemic brain tissue, 93.6% of the available 0.14 mg/ml NIMO was released into the buffer solution under 8 h release time. According to this in vitro study, the presented pH-sensitive drug carrier system could be useful to selectively target ischemic brain regions characterized by acidosis, to achieve neuroprotection at tissue zones at risk of injury, without any undesirable side effects caused by systemic drug administration., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Background: The 1,4-dihydropyridines (DHPs) are one of the most frequently prescribed classes of antihypertensive monotherapeutic agents worldwide. In addition to treating hypertension, DHPs also exert other beneficial effects, including hepatoprotective effects. However, the mechanism underlying the hepatoprotection remains unclear., Methods: Biochemical AlphaScreen and cell-based reporter assays were employed to detect the activities of DHPs towards FXR. A crystallographic analysis was adopted to study the binding modes of four DHPs in complex with FXR. Acetaminophen (APAP)-treated wild-type and FXR knockout mice were used to investigate the functional dependence of the effects of the selected DHPs on FXR., Results: A series of DHPs were uncovered as FXR ligands with different activities for FXR, suggesting FXR might serve as an alternative drug target for DHPs. The structural analysis illustrated the specific three-blade propeller binding modes of four DHPs to FXR and explained the detailed mechanisms by which DHPs bind to and are recognized by FXR. The results in mice demonstrated that cilnidipine protected the liver from APAP-induced injury in an FXR-dependent manner., Conclusions: This study reports the crystal structures of FXR in complex with four DHPs, and confirms that DHPs exert hepatoprotection by targeting FXR., General Significance: Our research not only reveals valuable insight for the design and development of next-generation Ca 2+ blocker drugs to provide safer and more effective treatments for cardiovascular disorders but also provides a novel and safe structural template for the development of drugs targeting FXR. Moreover, DHPs might be potentially repurposed to treat FXR-mediated diseases other than hypertension., (Copyright © 2018. Published by Elsevier B.V.)

Cone snails are a diverse group of predatory marine invertebrates that deploy remarkably complex venoms to rapidly paralyse worm, mollusc or fish prey. ω-Conotoxins are neurotoxic peptides from cone snail venoms that inhibit Ca v 2.2 voltage-gated calcium channel, demonstrating potential for pain management via intrathecal (IT) administration. Here, we isolated and characterized two novel ω-conotoxins, MoVIA and MoVIB from Conus moncuri, the first to be identified in vermivorous (worm-hunting) cone snails. MoVIA and MoVIB potently inhibited human Ca v 2.2 in fluorimetric assays and rat Ca v 2.2 in patch clamp studies, and both potently displaced radiolabeled ω-conotoxin GVIA ( 125 I-GVIA) from human SH-SY5Y cells and fish brain membranes (IC 50 2-9 pM). Intriguingly, an arginine at position 13 in MoVIA and MoVIB replaced the functionally critical tyrosine found in piscivorous ω-conotoxins. To investigate its role, we synthesized MoVIB-[R13Y] and MVIIA-[Y13R]. Interestingly, MVIIA-[Y13R] completely lost Ca v 2.2 activity and MoVIB-[R13Y] had reduced activity, indicating that Arg at position 13 was preferred in these vermivorous ω-conotoxins whereas tyrosine 13 is preferred in piscivorous ω-conotoxins. MoVIB reversed pain behavior in a rat neuropathic pain model, confirming that vermivorous cone snails are a new source of analgesic ω-conotoxins. Given vermivorous cone snails are ancestral to piscivorous species, our findings support the repurposing of defensive venom peptides in the evolution of piscivorous Conidae.

A rapid and sensitive method was established to determine amlodipine enantiomers using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Stereoselective separation was performed on CHIRALCEL OZ-RH column (150 mm × 4.6 mm i.d., 5 μm) with acetonitrile-water (10 mM ammonium acetate, 0.5% ammonia solution) (95:5, v/v) at a flow rate of 0.5 mL/min. The substances were detected by mass spectrometer equipped with an electrospray ionization source interface in positive ion mode. Multiple reaction monitoring was selected with the transition of the m/z 409.1 → 238.0 for amlodipine enantiomers and m/z 237.0 → 194.1 for carbamazepine (IS) respectively. Calibration curves were linear at the range of 0.9375-120 ng/mL for both isomers with r > 0.99, while using a lower sample volume (50 μL) compared with previously reported enantiospecific methods The accuracy was at the range of 84.1-119.0% for R-amlodipine, and 87.4-118.2% for S-amlodipine, respectively. The within- and between-run precision (CV%) was within 10% in all cases for both enantiomers. Enantiomers were stable under different conditions, e.g. processed sample, short-term, residue, long-term and freeze/thaw. The LC-MS/MS method was successfully applied in pharmacokinetic study of amlodipine enantiomers in rats. It was observed the concentration of the S- amlodipine was significantly higher than that of the R-amlodipine in racemate-treated group. And there was no significant difference in the pharmacokinetic profiles of the S-amlodipine between the 10 mg/kg racemate- and 5 mg/kg S-amlodipine-treated groups. In addition, it was the first time to find that the main pharmacokinetic parameters (AUC (0-t) , AUC (0-∞) and C max ) of R-amlodipine were significantly lower in the 5 mg/kg R-amlodipine-treated group compared with the racemate-treated group., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Nimodipine (NIM) is a calcium channel-blocking agent, which in the solid state exhibits two crystalline modifications, Mode I and Mode II. The first one is a racemic mixture, while the second is a conglomerate. Because the drug has poor aqueous solubility and Mode I is twice as soluble as Mode II, the former is widely preferred for the development of pharmaceutical forms. In order to study the effect of thermal stimuli on the behavior of NIM, an analytical method was developed coupling ATR-FTIR spectroscopy to Multivariate Curve Resolution with Alternating Least Squares (MCR-ALS). The method allowed to monitor the transformations of each polymorph, their respective mixtures and commercial samples, during the thermal treatment. It was observed that Mode II experienced changes during the experiments and the chemometric technique provided the abundance profile and the pure spectra of the different species involved. In this way, it was established that Mode II has two transitions, at 116.8 °C and 131.9 °C, which reflect that Mode II is first transformed into Mode I, which then melts. The liquid phase solidifies to give an amorphous (AM) vitreous solid, which does not revert to the crystalline state. The analysis of a commercial sample of NIM exhibited the similar transformations than Mode II; however, a pronounced decrease was noted in the first transition temperature (95 °C), whereas the second remained essentially unchanged (131.6 °C). This could be a result of the presence of mixtures of Mode I and Mode II (0.32:0.68) in the bulk solid, as confirmed by the analysis of a physical mixture of crystals of Modes I and II. Therefore, it was concluded that the developed ATR-FTIR/MCR-ALS method is suitable for the detailed analysis of the crystalline forms of NIM in bulk drug and enables de study of their possible thermally promoted interconversions., (Copyright © 2018 Elsevier B.V. All rights reserved.)

To understand the diversity of scorpion venom, RNA from venomous glands from a sawfinger scorpion, Serradigitus gertschi , of the family Vaejovidae, was extracted and used for transcriptomic analysis. A total of 84,835 transcripts were assembled after Illumina sequencing. From those, 119 transcripts were annotated and found to putatively code for peptides or proteins that share sequence similarities with the previously reported venom components of other species. In accordance with sequence similarity, the transcripts were classified as potentially coding for 37 ion channel toxins; 17 host defense peptides; 28 enzymes, including phospholipases, hyaluronidases, metalloproteases, and serine proteases; nine protease inhibitor-like peptides; 10 peptides of the cysteine-rich secretory proteins, antigen 5, and pathogenesis-related 1 protein superfamily; seven La1-like peptides; and 11 sequences classified as "other venom components". A mass fingerprint performed by mass spectrometry identified 204 components with molecular masses varying from 444.26 Da to 12,432.80 Da, plus several higher molecular weight proteins whose precise masses were not determined. The LC-MS/MS analysis of a tryptic digestion of the soluble venom resulted in the de novo determination of 16,840 peptide sequences, 24 of which matched sequences predicted from the translated transcriptome. The database presented here increases our general knowledge of the biodiversity of venom components from neglected non-buthid scorpions.

Objectives: The aim of this study was to evaluate the ability of four calcium channel blockers (CCBs), namely verapamil, diltiazem, nicardipine (NIC) and nifedipine (NIF), to enhance the susceptibility of Candida glabrata strains to fluconazole (FLC)., Methods: Synergistic antifungal effects of the CCBs with FLC were examined by the chequerboard method, and fractional inhibitory concentration indices (FICIs) were determined. The time-kill curve method was used for the most promising combination to further evaluate the synergetic effects., Results: NIC showed an additive effect with FLC against FLC-resistant and FLC-susceptible-dose-dependent strains (DSY 565 and CBS 138) known to express efflux pumps, but not against FLC-susceptible strains. NIF exhibited an additive effect with FLC both by the chequerboard method (0.510 CFU/mL decrease in viable count). In addition, NIF had its own antifungal effect consistently against most of the strains used in this study, with minimum inhibitory concentrations (MICs) of 8μg/mL., Conclusions: NIC showed an additive effect with FLC against FLC-resistant C. glabrata strains, most probably via efflux pump inhibition as demonstrated selectively in FLC-resistant strains with known efflux pumps. NIF displayed a promising antifungal effect alone as well as an additive effect with FLC against most of the strains., (Copyright © 2018 International Society for Chemotherapy of Infection and Cancer. Published by Elsevier Ltd. All rights reserved.)

The pressure-temperature phase diagram of the dimorphism of racemic m-nisoldipine is constructed using temperatures and enthalpies of fusion of forms A and B. At ordinary pressure, the transition from form B to form A is found to occur around 192K, which indicates that these polymorphs are enantiotropically related and that form A is stable at room temperature. Nevertheless, the phase relationship turns to be monotropic when pressures become greater than about 100MPa, which indicates that form B becomes the sole stable phase., (Copyright © 2018 Académie Nationale de Pharmacie. Published by Elsevier Masson SAS. All rights reserved.)

The aim of this study was to improve the oral bioavailability of a practically insoluble drug, efonidipine hydrochloride (EFH), by agglomeration in acid solution/gastric fluid. The EFH nanosuspension was prepared by the wet-milling method with F68 as a dispersing agent, SDS as an auxiliary stabilizer and l-arginine as a pH adjusting agent. The EFH nanosuspension have been prepared in industrial scale-up. The dissolution rate of the EFH nanosuspension was greater than that of bulk EFH. An in vitro intestinal permeability study showed a clear increase in the apparent permeability of different intestinal segments compared with bulk EFH. Also, a pharmacokinetic study showed that the C max and AUC 0-24h of the nanosuspensions were approximately 1.76-fold and 2.2-fold greater than that of bulk EFH, respectively, and there was no significant difference compared with commercial tablets. It appears that wet-milling offers an effective approach to improve the dissolution rate and oral absorption of this practically insoluble drug., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Since Ca v 3.2 T-type Ca 2+ channels (T-channels) expressed in the primary afferents and CNS contribute to intractable pain, we explored T-channel-blocking components in distinct herbal extracts using a whole-cell patch-clamp technique in HEK293 cells stably expressing Ca v 3.2 or Ca v 3.1, and purified and identified sophoraflavanone G (SG) as an active compound from SOPHORAE RADIX (SR). Interestingly, hop-derived SG analogues, (2S)-6-prenylnaringenin (6-PNG) and (2S)-8-PNG, but not naringenin, also blocked T-channels; IC 50 (μM) of SG, (2S)-6-PNG and (2S)-8-PNG was 0.68-0.75 for Ca v 3.2 and 0.99-1.41 for Ca v 3.1. (2S)-6-PNG and (2S)-8-PNG, but not SG, exhibited reversible inhibition. The racemic (2R/S)-6-PNG as well as (2S)-6-PNG potently blocked Ca v 3.2, but exhibited minor effect on high-voltage-activated Ca 2+ channels and voltage-gated Na + channels in differentiated NG108-15 cells. In mice, the mechanical allodynia following intraplantar (i.pl.) administration of an H 2 S donor was abolished by oral or i.p. SR extract and by i.pl. SG, (2S)-6-PNG or (2S)-8-PNG, but not naringenin. Intraperitoneal (2R/S)-6-PNG strongly suppressed visceral pain and spinal ERK phosphorylation following intracolonic administration of an H 2 S donor in mice. (2R/S)-6-PNG, administered i.pl. or i.p., suppressed the neuropathic allodynia induced by partial sciatic nerve ligation or oxaliplatin, an anti-cancer agent, in mice. (2R/S)-6-PNG had little or no effect on open-field behavior, motor performance or cardiovascular function in mice, and on the contractility of isolated rat aorta. (2R/S)-6-PNG, but not SG, was detectable in the brain after their i.p. administration in mice. Our data suggest that 6-PNG, a hop component, blocks T-channels, and alleviates neuropathic and visceral pain with little side effects., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Sophorae Flavescentis Radix (SFR) is a medicinal herb with many functions that are involved in anti-inflammation, antinociception, and anticancer. SFR is also used to treat a variety of itching diseases. Matrine (MT) is one of the main constituents in SFR and also has the effect of relieving itching, but the antipruritic mechanism is still unclear. Here, we investigated the effect of MT on anti-pruritus. In acute and chronic itch models, MT significantly inhibited the scratching behavior not only in acute itching induced by histamine (His), chloroquine (CQ) and compound 48/80 with a dose-depended manner, but also in the chronic pruritus models of atopic dermatitis (AD) and acetone-ether-water (AEW) in mice. Furthermore, MT could be detected in the blood after intraperitoneal injection (i.p.) and subcutaneous injection (s.c.). Finally, electrophysiological and calcium imaging results showed that MT inhibited the excitatory synaptic transmission from dorsal root ganglion (DRG) to the dorsal horn of the spinal cord by suppressing the presynaptic N-type calcium channel. Taken together, we believe that MT is a novel drug candidate in treating pruritus diseases, especially for histamine-independent and chronic pruritus, which might be attributed to inhibition of the presynaptic N-type calcium channel.

The proteins Orai1 and STIM1 control store-operated Ca 2+ entry (SOCE) into cells. SOCE is important for migration, invasion and metastasis of MDA-MB-231 human triple negative breast cancer (TNBC) cells and has been proposed as a target for cancer drug discovery. Two hit compounds from a medium throughput screen, displayed encouraging inhibition of SOCE in MDA-MB-231 cells, as measured by a Fluorescence Imaging Plate Reader (FLIPR) Ca 2+ assay. Following NMR spectroscopic analysis of these hits and reassignment of their structures as 5-hydroxy-5-trifluoromethylpyrazolines, a series of analogues was prepared via thermal condensation reactions between substituted acylhydrazones and trifluoromethyl 1,3-dicarbonyl arenes. Structure-activity relationship (SAR) studies showed that small lipophilic substituents at the 2- and 3-positions of the RHS and 2-, 3- and 4-postions of the LHS terminal benzene rings improved activity, resulting in a novel class of potent and selective inhibitors of SOCE., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Nifedipine and isradipine are prominent examples of calcium channel blockers with a 1,4-dihydropyridine (DHP) scaffold. Although successfully used in clinics since decades for the treatment of hypertension, the binding mechanism to their target, the L-type voltage-gated calcium channel Cav1.2, is still incompletely understood. Recently, novel DHP derivatives with a condensed ring system have been discovered that show distinct selectivity profiles to different calcium channel subtypes. This property renders this DHP class as a promising tool to achieve selectivity towards distinct calcium channel subtypes. In this study, we identified a common binding mode for prominent DHPs nifedipine and isradipine using docking and pharmacophore analysis that is also able to explain the structure-activity relationship of a small subseries of DHP derivatives with a condensed ring system. These findings were used to guide the synthesis of twenty-two novel DHPs. An extensive characterization using 1 H NMR, 13 C NMR, mass spectra and elemental analysis was followed by whole cell patch clamp assays for analyzing activity at Cav1.2 and Cav3.2. Two compounds were identified with significant activity against Cav1.2. Additionally, we identified four compounds active against Cav3.2 of which three were selective over Cav1.2. Novel binding modes were analyzed using docking and pharmacophore analysis as well as molecular dynamics simulations., (Copyright © 2018 Elsevier Masson SAS. All rights reserved.)

Both N- and T-type calcium ion channels have been implicated in pain transmission and the N-type channel is a well-validated target for the treatment of neuropathic pain. An SAR investigation of a series of substituted aminobenzothiazoles identified a subset of five compounds with comparable activity to the positive control Z160 in a FLIPR-based intracellular calcium response assay measuring potency at both Ca V 2.2 and Ca V 3.2 channels. These compounds may form the basis for the development of drug leads and tool compounds for assessing in vivo effects of variable modulation of Ca V 2.2 and Ca V 3.2 channels., (Crown Copyright © 2018. Published by Elsevier Ltd. All rights reserved.)

In this study, we aimed to synthesize a novel blocker of transient receptor potential canonical 6 (TRPC6). The sp 2 carbon atoms of the aminoindane skeleton of the known inhibitor were replaced with sp 3 carbon atoms to increase the molecular complexity, measured by fraction sp 3 (Fsp 3 ). The representative compound, a bicyclo[4.3.0]nonane derivative DS88790512, inhibited TRPC6 with an IC 50 value of 11 nM. Notably, DS88790512 exhibited excellent selectivity against hERG and hNa V 1.5 channels, and was identified as an orally bioavailable compound., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

In this paper, a stable amorphous solid dispersion of an antihypertensive drug, amlodipine besylate (AMB) was prepared by entrapping it in a polymer matrix, polyvinyl pyrrollidone, in different weight ratios (AMB/PVP 05:95, 10:90, 20:80, 30:70). The glass forming ability of all binary dispersions were studied by means of differential scanning calorimetry and found good correlation between experimental T g and Fox Flory's prediction. By considering the daily dosage limit of 5 mg, a weight ratio of 05:95 was further considered for the study. The structures of neat and binary of AMB were characterized by density functional theory, Fourier transform infrared spectroscopy, Fourier transform Raman spectroscopy and UV-visible spectroscopy. Further, detailed molecular dynamics of both pure and binary were investigated using broadband dielectric spectroscopy to judge the physical stability of the amorphous dispersions. Translation-rotation coupling of AMB possibly explains the dual conductivity and dipolar nature of the secondary relaxation in neat AMB. Thus, the binary dispersion of AMB with commercially acceptable weight ratio with strong glass forming behaviour and better shelf life was prepared and characterized for practical applications., (Copyright © 2018. Published by Elsevier B.V.)

Purpose: The overall purpose of this study was to understand the impact of different biorelevant media types on solubility and crystallization from supersaturated solutions of model compounds (atazanavir, ritonavir, tacrolimus and cilnidipine). The first aim was to understand the influence of the lecithin content in FaSSIF. As the human intestinal fluids (HIFs) contain a variety of bile salts in addition to sodium taurocholate (STC), the second aim was to understand the role of these bile salts (in the presence of lecithin) on solubility and crystallization from supersaturated solutions, METHODS: To study the impact of lecithin, media with 3 mM STC concentration but varying lecithin concentration were prepared. To test the impact of different bile salts, a new biorelevant medium (Composite-SIF) with a composition simulating that found in the fasted HIF was prepared. The crystalline and amorphous solubility was determined in these media. Diffusive flux measurements were performed to determine the true supersaturation ratio at the amorphous solubility of the compounds in various media. Nucleation induction times from supersaturated solutions were measured at an initial concentration equal to the amorphous solubility (equivalent supersaturation) of the compound in the given medium., Results: It was observed that, with an increase in lecithin content at constant STC concentration (3 mM), the amorphous solubility of atazanavir increased and crystallization was accelerated. However, the crystalline solubility remained fairly constant. Solubility values were higher in FaSSIF compared to Composite-SIF. Longer nucleation induction times were observed for atazanavir, ritonavir and tacrolimus in Composite-SIF compared to FaSSIF at equivalent supersaturation ratios., Conclusions: This study shows that variations in the composition of SIF can lead to differences in the solubility and crystallization tendency of drug molecules, both of which are critical when evaluating supersaturating systems.

α-Conotoxins are disulfide-bonded peptides from cone snail venoms and are characterized by their affinity for nicotinic acetylcholine receptors (nAChR). Several α-conotoxins with distinct selectivity for nAChR subtypes have been identified as potent analgesics in animal models of chronic pain. However, a number of α-conotoxins have been shown to inhibit N-type calcium channel currents in rodent dissociated dorsal root ganglion (DRG) neurons via activation of G protein-coupled GABA B receptors (GABA B R). Therefore, it is unclear whether activation of GABA B R or inhibition of α9α10 nAChRs is the analgesic mechanism. To investigate the mechanisms by which α-conotoxins provide analgesia, we synthesized a suite of Vc1.1 analogues where all residues, except the conserved cysteines, in Vc1.1 were individually replaced by alanine (A), lysine (K), and aspartic acid (D). Our results show that the amino acids in the first loop play an important role in binding of the peptide to the receptor, whereas those in the second loop play an important role for the selectivity of the peptide for the GABA B R over α9α10 nAChRs. We designed a cVc1.1 analogue that is >8000-fold selective for GABA B R-mediated inhibition of high voltage-activated (HVA) calcium channels over α9α10 nAChRs and show that it is analgesic in a mouse model of chronic visceral hypersensitivity (CVH). cVc1.1[D11A,E14A] caused dose-dependent inhibition of colonic nociceptors with greater efficacy in ex vivo CVH colonic nociceptors relative to healthy colonic nociceptors. These findings suggest that selectively targeting GABA B R-mediated HVA calcium channel inhibition by α-conotoxins could be effective for the treatment of chronic visceral pain.

The oral bioavailability of felodipine (FEL) is very low, i.e., about 15%. This could be due to low water solubility and hepatic first-pass effect. The objective of the present study was to develop FEL microemulsion-based gel, to bypass the first pass effect, for buccal delivery. The optimized FEL microemulsion (OPT-MEF) was used to prepare buccoadhesive gels, with varying concentrations of hydroxypropyl methylcellulose (HPMC) E4M and polycarbophil (PCP), and evaluated. The cross-linking of the PCP gelling agent was done by adjusting the pH with a neutralizing agent, triethanolamine (TEA). The formulations, namely drug suspension, OPT-MEF, microemulsion-based buccal gel containing 1% w/v (MEF-E4M1), 2% w/v (MEF-E4M2), and 3% w/v (MEF-E4M3) of HPMC K4M and 1% w/v (MEF-PCP1), 2% w/v (MEF-PCP2), and 3% w/v (MEF-PCP3) of PCP were prepared and optimized on the basis of ex vivo permeation study, mucoadhesion force, and viscosity. The optimized buccal gel (MEF-PCP1) showed significantly higher (p < 0.01) permeation flux (J = 0.44 ± 0.16 mg/cm 2 /h), when compared with the drug suspension (J = 0.17 ± 0.14 mg/cm 2 /h). The permeation enhancement ratio of MEF-PCP1 was found to be 2.59 times higher than that of the aqueous suspension of the drug. The texture profile analysis of MEF-PCP1 was performed which showed spreadability (3.2 mJ), extrudability (151.8 mJ), hardness (13.8 g), and adhesiveness (41.0 g), and results indicated good spreadability and adhesiveness. The rheological study revealed the pseudoplastic flow behavior of MEF-PCP1 buccal gel. The C max value 9.21 ± 2.88 μg/ml of MEF-PCP1 gel was found to be significantly higher (P < 0.01) compared to the same dose administered by oral route (C max value 3.51 ± 1.74 μg/ml). The relative bioavailability (F r ) of the optimized MEF-PCP1 buccal gel was about 397.39% higher than that of oral route. In conclusion, consistent and effective buccal gel containing optimized FEL-loaded microemulsion, with improved buccal permeation and pharmacokinetic parameters was developed successfully to improve the bioavailability of FEL.

Background and Purpose: Voltage-gated calcium channels are involved in nociception in the CNS and in the periphery. N-type (Ca v 2.2) and T-type (Ca v 3.1, Ca v 3.2 and Ca v 3.3) voltage-gated calcium channels are particularly important in studying and treating pain and epilepsy., Experimental Approach: In this study, whole-cell patch clamp electrophysiology was used to assess the potency and mechanism of action of a novel ortho-phenoxylanilide derivative, MONIRO-1, against a panel of voltage-gated calcium channels including Ca v 1.2, Ca v 1.3, Ca v 2.1, Ca v 2.2, Ca v 2.3, Ca v 3.1, Ca v 3.2 and Ca v 3.3., Key Results: MONIRO-1 was 5- to 20-fold more potent at inhibiting human T-type calcium channels, hCa v 3.1, hCa v 3.2 and hCa v 3.3 (IC 50 : 3.3 ± 0.3, 1.7 ± 0.1 and 7.2 ± 0.3 μM, respectively) than N-type calcium channel, hCa v 2.2 (IC 50 : 34.0 ± 3.6 μM). It interacted with L-type calcium channels Ca v 1.2 and Ca v 1.3 with significantly lower potency (IC 50  > 100 μM) and did not inhibit hCa v 2.1 or hCa v 2.3 channels at concentrations as high as 100 μM. State- and use-dependent inhibition of hCa v 2.2 channels was observed, whereas stronger inhibition occurred at high stimulation frequencies for hCa v 3.1 channels suggesting a different mode of action between these two channels., Conclusions and Implications: Selectivity, potency, reversibility and multi-modal effects distinguish MONIRO-1 from other low MW inhibitors acting on Ca v channels involved in pain and/or epilepsy pathways. High-frequency firing increased the affinity for MONIRO-1 for both hCa v 2.2 and hCa v 3.1 channels. Such Ca v channel modulators have potential clinical use in the treatment of epilepsies, neuropathic pain and other nociceptive pathophysiologies., Linked Articles: This article is part of a themed section on Recent Advances in Targeting Ion Channels to Treat Chronic Pain. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.12/issuetoc., (© 2017 The British Pharmacological Society.)

Ca v 3.2 T-type calcium channels are important regulators of pain signals in the afferent pain pathway, and their activities are dysregulated during various chronic pain states. Therefore, it is reasonable to predict that inhibiting T-type calcium channels in dorsal root ganglion neurons and in the spinal dorsal horn can be targeted for pain relief. This is supported by early pharmacological studies with T-type channel blockers, such as ethosuximide, and by analgesic effects of siRNA depletion of Ca v 3.2 channels. In the past 5 years, considerable effort has been applied towards identifying novel classes of T-type calcium channel blockers. Here, we review recent developments in the discovery of novel classes of T-type calcium channel blockers, and their analgesic effects in animal models of pain and in clinical trials., Linked Articles: This article is part of a themed section on Recent Advances in Targeting Ion Channels to Treat Chronic Pain. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.12/issuetoc., (© 2017 The British Pharmacological Society.)

Nimodipine may be of interest to treat behavioral alterations and memory deficits. However, its oral administration is hampered by a low bioavailability. The aim of this work was to develop pegylated nanoparticles as oral carriers of nimodipine and test their capability to both reverse the anxiety and protect against cognitive impairment of in stressed mice. Pegylated nanoparticles (NMD-NP/PEG), with a size of 190 nm and a payload of 68 µg/mg, significantly improve the oral bioavailability of nimodipine; about 7-times higher than for the control drug solution (62% vs 9%). The effect of oral nimodipine on the anxiety and cognitive capabilities in a model of stressed mice was also evaluated. NMD-NP/PEG displayed a poor effect on the anxiety-like behavior of animals. Nevertheless, only the treatment with NMD-NP/PEG exerted a protective effect against the memory impairments induced by chronic corticosterone administration, improving the cognitive capabilities of animals when compared with controls. These pegylated nanocarriers may represent a useful strategy to develop new oral treatments for preventing from cognitive impairments., (Copyright © 2018 Elsevier B.V. All rights reserved.)

In this study, spherical shaped chiral mesoporous silica nanoparticles (CMS) was biomimetic synthesized using histidine derivatives (C 16 -L-histidine) as template via the sol-gel reaction and employed as poorly water-soluble drug nimodipine (NMP) carrier. Characteristics of CMS and its application as drug carrier were intensively investigated and compared with MCM41. Then NMP was respectively loaded into CMS and MCM41 with the drug: carrier weight ratio of 2:1. Structural features of NMP before and after drug loading were systemically characterized. The results demonstrated that hydrogen bonds were formed between NMP and carriers during the drug loading process. After drug loading, crystalline state of NMP effectively converted into modification L and amorphous state, and the first form turned out to be easily removed by washing. On the other hand, drug dissolution rate was significantly improved after drug loading, and the best result came from NMP-C3 sample. It was able to release 17.83% of drug within 60 min, which was 6.8-fold higher than the release amount of pure NMP. Undoubtedly, NMP-C3 presented the highest relative bioavailability (386.22%), and the best therapeutic effect. Meanwhile, CMS improved the brain distribution of NMP in vivo., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Following the premises of the multitarget-directed ligands approach for the drug R&D against neurodegenerative diseases, where Alzheimer's disease (AD) outstands, we have synthesized and evaluated analogues of the gramine derivative ITH12657 (1-benzyl-5-methyl-3-(piperidin-1-ylmethyl-1H-indole, 2), which had shown important neuroprotective properties, such as blocking effect of voltage-gated Ca 2+ channels (VGCC), and prevention of phosphoprotein phosphatase 2A (PP2A) inhibition. The new analogues present different substitutions at the pending phenyl ring, what slightly modified their pharmacological characteristics. The VGCC blockade was enhanced in derivatives possessing nitro groups, while the pro-PP2A feature was ameliorated by the presence of fluorine. Chlorine atoms supplied good activities over the two biological targets aimed; nevertheless that substitution provoked loss of viability at 100-fold higher concentrations (10 μM), what discards them for a deeper pharmacological study. Overall, the para-fluorine derivative of ITH12657 was the most promising candidate for further preclinical assays., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

A T-type calcium channel inhibiting natural product cochlearoid B was synthesized for the first time in 7 linear steps via a convergent strategy exploiting the Suzuki-Miyaura cross coupling and the acid promoted Prins cyclization cascade. This strategy allows rapid access to its structural analogues for further therapeutical development.

α-Conotoxins (α-CTxs) are small peptides composed of 11 to 20 amino acid residues with two disulfide bridges. Most of them potently and selectively target nicotinic acetylcholine receptor (nAChR) subtypes, and a few were found to inhibit the GABA B receptor (GABA B R)-coupled N-type calcium channels (Cav2.2). However, in all of α-CTxs targeting both receptors, the disulfide connectivity arrangement "C¹-C³, C²-C⁴" is present. In this work, a novel α4/7-CTx named Lt1.3 (GCCSHPACSGNNPYFC-NH₂) was cloned from the venom ducts of Conus litteratus ( C. litteratus ) in the South China Sea. Lt1.3 was then chemically synthesized and two isomers with disulfide bridges "C¹-C³, C²-C⁴" and "C¹-C⁴, C²-C³" were found and functionally characterized. Electrophysiological experiments showed that Lt1.3 containing the common disulfide bridges "C¹-C³, C²-C⁴" potently and selectively inhibited α3β2 nAChRs and not GABA B R-coupled Cav2.2. Surprisingly, but the isomer with the disulfide bridges "C¹-C⁴, C²-C³" showed exactly the opposite inhibitory activity, inhibiting only GABA B R-coupled Cav2.2 and not α3β2 nAChRs. These findings expand the knowledge of the targets and selectivity of α-CTxs and provide a new structural motif to inhibit the GABA B R-coupled Cav2.2., Competing Interests: The authors have no conflicts of interests to declare.

From a series of (1 R , 1 S )-1[β-(phenylalkoxy)-(phenetyl)]-1 H -pyrazolium hydrochloride as new analogues of SKF-96365, one has an interesting effect for endoplasmic reticulum (ER) Ca 2+ release and store-operated Ca 2+ entry (SOCE) (IC 50 25 μM) on the PLP-B lymphocyte cell line. A successful resolution of (±) 1-phenyl-2-(1 H -pyrazol-1-yl)ethan-1-ol has been developed by using the method of "half-concentration" in the presence of (+)-(1 S )- or (-)-(1 R )-CSA., Competing Interests: The authors declare no conflict of interest.

Ethnopharmacological Relevance: Cyperus species are famous for their traditional uses and very commonly used for their anti-spasmodic and anti-diarrheal activities. Cyperus niveus Retz. is used in local traditional system of medicine in Pakistan to treat diarrhea and emesis., Aim of the Study: The aim of the study was to validate the traditional uses and to provide the possible mechanisms for the medicinal use of Cyperus niveus Retz. as anti-spasmodic, anti-diarrheal and anti emetic., Materials and Methods: The in-vivo studies of anti-diarrheal, charcoal meal GI transit test and anti-emetic activities were conducted in rats, mice and chicks respectively, while isolated tissues of rabbit's jejunum and rat's ileum were used for in-vitro experiments. Phytochemical analysis was also undertaken., Results: The phytochemical study of hydro-ethanolic extract of Cyperus niveus Retz. showed the presence of flavonoids, phenols, alkaloids, tannins, saponins and glycosides. Cn. Cr caused significant inhibition of castor oil-induced diarrhea in rats (300,500 & 700mg/kg) using loperamide (10mg/kg, p.o) as standard. Cn. Cr also significantly decreased the motility in charcoal meal GI transit test at 100-200mg/kg in mice, using atropine (3.0mg/kg) as positive control. In jejunum tissue, Cn. Cr relaxed carbachol(1µM) and K + (80mM)-induced contractions, similar to the effect of dicyclomine. Pre-incubation of isolated rat ileum tissues with Cn. Cr (0.1mg/mL) caused the corresponding shift of CCh concentration response curve (CRC) to right without decrease in max. response whereas at the concentration of 0.3mg/mL caused the rightward nonparallel shift with max. response suppression, similar to dicyclomine. Antimuscarinic effect was further confirmed when prior administration of Cn. Cr (0.1, 0.3 and 1mg/mL) caused concentration dependent inhibition of induced contractions of carbachol, comparable to atropine (1µM). To confirm the Ca 2+ channel blocking (CCB), the rabbit jejunum was pre-incubated with Cn. Cr (0.3 & 1.0mg/mL), produced a shift in CRCs of calcium toward right with decrease in the maximum response at next concentration, similar to that of dicyclomine. The organic fraction of Cyperus niveus Retz. (Cn. Dcm) showed Ca 2+ antagonist and anticholinergic activities with higher potency against K + (80mM) induced contractions, like verapamil, while aqueous fraction (Cn. Aq) relaxed only carbachol(1µM) induced contractions with no prominent effect on K + (80mM)-contractions even at the higher concentration of 10mg/mL, similar to atropine. Cn. Cr also showed significant anti-emetic effect in Chick emesis model using chlorpromazine as standard., Conclusion: This study shows the presence of antidiarrheal and spasmolytic activities in Cyperus niveus Retz. extract, mediated by dual blocking mechanisms of muscarinic receptors and Ca 2+ channels. The results further indicate the presence of anti-emetic activity in Cn. Cr, which may be because of its anti-muscarinic potential. This study provides the scientific bases to the traditional use of Cn. Cr in diarrhea and emesis., (Copyright © 2017 Elsevier B.V. All rights reserved.)

The seeds of Swietenia macrophylla King (SM) (Meliaceae) are used as a folk medicine for the treatment of hypertension in Malaysia. However, the antihypertensive and vasorelaxant effects of SM seeds are still not widely studied. Thus, this study was designed to investigate the in vivo antihypertensive effects and in vitro mechanism of vasorelaxation of a 50% ethanolic SM seed extract (SM50) and the fingerprint of SM50 was developed through tri-step Fourier transform infrared (FTIR) spectroscopy. The vasorelaxant activity and the underlying mechanisms of SM50 were evaluated on thoracic aortic rings isolated from Sprague-Dawley rats in the presence of antagonists. The pharmacological effect of SM50 was investigated by oral administration of spontaneously hypertensive rats (SHRs) with three different doses of SM50 (1000, 500, and 250 mg/kg/day) for 4 weeks and their systolic blood pressure (SBP) and diastolic blood pressure (DBP) values were measured weekly using tail-cuff method. The tri-step FTIR macro-fingerprint of SM50 showed that SM50 contains stachyose, flavonoids, limonoids, and ester, which may contribute to its vasorelaxant effect. The results showed that the vasorelaxant activity of SM50 was mostly attributed to channel-linked receptors pathways through the blockage of voltage-operated calcium channels (VOCC). SM50 also acts as both potassium channels opener and inositol triphosphate receptor (IP 3 R) inhibitor, followed by β 2 -adrenergic pathway, and ultimately mediated through the nitric oxide/soluble guanylyl cyclase/cyclic 3',5'-guanosine monophosphate (NO/sGC/cGMP) signaling pathways. The treatment of SM50 also significantly decreased the SBP and DBP in SHRs. In conclusion, the antihypertensive mechanism of SM50 was mediated by VOCC, K + channels, IP 3 R, G-protein-coupled β 2 -adrenergic receptor, and followed by NO/sGC/cGMP signaling mechanism pathways in descending order. The data suggested that SM50 has the potential to be used as a herbal medicament to treat hypertension.

The oral bioavailability of felodipine, a dihydropyridine calcium channel antagonist, is about 15%. This may be due to poor water solubility, and a lower intestinal permeability than a BCS class I drug, and hepatic first-pass metabolism of the drug. Many drugs are unpopular due to solubility issues. The goal of this study was to develop and optimize a felodipine-containing microemulsion to improve the intestinal permeability and bioavailability of the drug. The felodipine microemulsions were developed with the selected components, i.e., α-linolenic acid as the oil phase, Tween 80 as a surfactant, and isopropyl alcohol as co-surfactant using Box-Behnken design and characterized for in vitro release and particle size. The optimized felodipine-loaded microemulsion was investigated for physicochemical interaction, surface morphology, intestinal permeability, rheology, cytotoxicity, cellular uptake, pharmacodynamic (electrocardiogram and heart rate variability), and pharmacokinetic studies to explore its suitability as a promising oral drug delivery system for the treatment of hypertension. The optimized felodipine-loaded microemulsion showed significantly higher (P < 0.05) apparent permeability coefficients (Papp) at 7.918 × 10 -5  cm/s after 1 h, when compared with conventional formulations that are marketed tablet, drug oily solution, and drug emulsion, which showed a maximum Papp of 3.013, 4.428, and 5.335 × 10 -5  cm/s, respectively. The optimized felodipine-loaded microemulsion showed biocompatibility and no cytotoxicity. Cellular uptake studies confirmed payload delivery to a cellular site on the J774.A1 cell line. The rheology study of the optimized felodipine-loaded microemulsion revealed Newtonian-type flow behavior and discontinuous microemulsion formation. In pharmacodynamic studies, significant differences in parameters were observed between the optimized felodipine-loaded microemulsion and marketed formulation. The optimized felodipine-loaded microemulsion showed significantly higher (p < 0.01) C max (7.12 ± 1.04 μg/ml) than marketed tablets (2.44 ± 1.03 μg/ml). It was found that AUC last obtained from the optimized felodipine-loaded microemulsion (84.53 ± 10.73 μg h/ml) was significantly higher (p < 0.01) than the marketed tablet (27.41 ± 5.54 μg h/ml). The relative bioavailability (Fr) of the optimized felodipine-loaded microemulsion was about 308.3% higher than that of the marketed formulation. The results demonstrate that the prepared microemulsion is an advanced and efficient oral delivery system of felodipine for the management of hypertension.

Dihydropyrimidinones are heterocycles with a pyrimidine moiety in the ring nucleus, which, in recent decades, have aroused interest in medicinal chemistry due to alleged versatile biological activity. In this systematic review, we describe the currently published activities of dihydropyrimidinone derivatives. Between 1990 and December 31st, 2016, 115 articles outlined biological activities or toxicity of DHPM derivatives, 12 of those involved in vivo experiments. The main activities associated with this class of compounds are antitumoral (43 articles), anti-inflammatory (12 articles), antibacterial (20 articles) and calcium channel antagonism/inhibition (14 articles). Antitumoral activity is the main biological property evaluated, since the main representative compound of this class (monastrol) is a known Eg5 kinesin inhibitor. This review depicts a variety of other pharmacological activities associated with DHPM derivatives, but the main findings are essentially in vitro characteristics of the substances. This review presents the current state of the art of DHPM biological activities and demonstrates that there is still a need for further in vivo studies to better delineate the pharmacological potential of this class of substances., (Copyright © 2017 Elsevier Masson SAS. All rights reserved.)

Pinus morrisonicola Hayata, usually called Taiwan five-leaf pine (5LP), is an endemic species in Taiwan and is traditionally used to relieve hypertension symptoms and improve cardiovascular function. In this study, the needle extract of 5LP was fractionated and analyzed by LC/MS/MS to search for possible antihypertensive candidates. In addition, bioassay-guided purification of the bioactive components was performed by Ca 2+ fluorescent signal (Fluo 4-AM) assays. Two dihydrobenzofuran lignans, pinumorrisonide A ( 1 ) and icariside E4 ( 2 ), and one acylated flavonoid glycoside, kaempferol 3- O -α-(6‴- p -coumaroylglucosyl-β-1,4-rhamnoside) ( 3 ) were characterized from the active fractions. The structure of a new compound 1 was established on the basis of 2D NMR spectroscopic and mass spectrometric analyses, and the known compounds 2 and 3 were identified by comparison of their physical and spectroscopic data with those reported in the literature. The purified compounds 1 - 3 exhibited significant inhibition of Ca 2+ fluorescence with IC 50 values of 0.71, 0.36, and 0.20 mM, respectively. A mechanism study showed that these compounds showed vasorelaxant effects by blocking the voltage-operated Ca 2+ channel (VOCC) and inhibiting Ca 2+ influx to the cytoplasmic. These results suggested that 5LP and the three characterized components could be promising antihypertensive candidates for the use as VOCC blockers., Competing Interests: The authors declare no conflict of interest.

P-glycoprotein (Pgp) is an efflux pump important in multidrug resistance of cancer cells and in determining drug pharmacokinetics. Pgp is a prototype ATP-binding cassette transporter with two nucleotide-binding domains (NBDs) that bind and hydrolyze ATP. Conformational changes at the NBDs (the Pgp engines) lead to changes across Pgp transmembrane domains that result in substrate translocation. According to current alternating access models (substrate-binding pocket accessible only to one side of the membrane at a time), binding of ATP promotes NBD dimerization, resulting in external accessibility of the drug-binding site (outward-facing, closed NBD conformation), and ATP hydrolysis leads to dissociation of the NBDs with the subsequent return of the accessibility of the binding site to the cytoplasmic side (inward-facing, open NBD conformation). However, previous work has not investigated these events under near-physiological conditions in a lipid bilayer and in the presence of transport substrate. Here, we used luminescence resonance energy transfer (LRET) to measure the distances between the two Pgp NBDs. Pgp was labeled with LRET probes, reconstituted in lipid nanodiscs, and the distance between the NBDs was measured at 37 °C. In the presence of verapamil, a substrate that activates ATP hydrolysis, the NBDs of Pgp reconstituted in nanodiscs were never far apart during the hydrolysis cycle, and we never observed the NBD-NBD distances of tens of Å that have previously been reported. However, we found two main conformations that coexist in a dynamic equilibrium under all conditions studied. Our observations highlight the importance of performing studies of efflux pumps under near-physiological conditions, in a lipid bilayer, at 37 °C, and during substrate-stimulated hydrolysis., (© 2017 by The American Society for Biochemistry and Molecular Biology, Inc.)

We report here the discovery and pharmacological characterization of N-(1-benzyl-1H-pyrazol-3-yl)-2-phenylacetamide derivatives as potent, selective, brain-penetrating T-type calcium channel blockers. Optimization focused mainly on solubility, brain penetration, and the search for an aminopyrazole metabolite that would be negative in an Ames test. This resulted in the preparation and complete characterization of compound 66b (ACT-709478), which has been selected as a clinical candidate.

We identified and characterized a series of pyrrole amides as potent, selective Ca v 3.2-blockers. This series culminated with the identification of pyrrole amides 13b and 26d, with excellent potencies and/or selectivities toward the Ca v 3.1- and Ca v 3.3-channels. These compounds display poor physicochemical and DMPK properties, making their use difficult for in vivo applications. Nevertheless, they are well-suited for in vitro studies., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

We identified and characterized a series of pyrazole amides as potent, selective Ca v 3.1-blockers. This series culminated with the identification of pyrazole amides 5a and 12d, with excellent potencies and/or selectivities toward the Ca v 3.2- and Ca v 3.3-channels. This compound displays poor DMPK properties, making its use difficult for in vivo applications. Nevertheless, this compound as well as analogous ones are well-suited for in vitro studies., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Cocrystallization of nifedipine (NFD) and isonicotinamide (INA) resulted in two monotropic cocrystal polymorphs. The thermodynamically more stable polymorph presents superior photostability compared to the other. Cocrystallization can be an efficient approach to address the stability deficit of dihydropyridine drugs.

Voltage-gated calcium (Ca V ) channels are widely expressed and are essential for the completion of multiple physiological processes. Close regulation of their activity by specific inhibitors and agonists become fundamental to understand their role in cellular homeostasis as well as in human tissues and organs. Ca V channels are divided into two groups depending on the membrane potential required to activate them: High-voltage activated (HVA, Ca V 1.1-1.4; Ca V 2.1-2.3) and Low-voltage activated (LVA, Ca V 3.1-3.3). HVA channels are highly expressed in brain (neurons), heart, and adrenal medulla (chromaffin cells), among others, and are also classified into subtypes which can be distinguished using pharmacological approaches. Cone snails are marine gastropods that capture their prey by injecting venom, "conopeptides", which cause paralysis in a few seconds. A subset of conopeptides called conotoxins are relatively small polypeptides, rich in disulfide bonds, that target ion channels, transporters and receptors localized at the neuromuscular system of the animal target. In this review, we describe the structure and properties of conotoxins that selectively block HVA calcium channels. We compare their potency on several HVA channel subtypes, emphasizing neuronal calcium channels. Lastly, we analyze recent advances in the therapeutic use of conotoxins for medical treatments., Competing Interests: The authors declare no conflict of interest.

To characterize the role of cAMP-dependent protein kinase (PKA) in regulating vascular Ca 2+ current through Ca v 1.2 channels [I Ca1.2 ], we have documented a marked capacity of the isoquinoline H-89, widely used as a PKA inhibitor, to reduce current amplitude. We hypothesized that the I Ca1.2 inhibitory activity of H-89 was mediated by mechanisms unrelated to PKA inhibition. To support this, an in-depth analysis of H-89 vascular effects on both I Ca1.2 and contractility was undertaken by performing whole-cell patch-clamp recordings and functional experiments in rat tail main artery single myocytes and rings, respectively. H-89 inhibited I Ca1.2 with a pIC 50 (M) value of about 5.5, even under conditions where PKA activity was either abolished by both the PKA antagonists KT5720 and protein kinase inhibitor fragment 6-22 amide or enhanced by the PKA stimulators 6-Bnz-cAMP and 8-Br-cAMP. Inhibition of I Ca1.2 by H-89 appeared almost irreversible upon washout, was charge carrier- and voltage-dependent, and antagonised by the Ca v 1.2 channel agonist (S)-(-)-Bay K 8644. H-89 did not alter both potency and efficacy of verapamil, did not affect current kinetics or voltage-dependent activation, while shifting to the left the 50% voltage of inactivation in a concentration-dependent manner. H-89 docked at the α 1C subunit in a pocket region close to that of (S)-(-)-Bay K 8644 docking, forming a hydrogen bond with the same, key amino acid residue Tyr-1489. Finally, both high K + - and (S)-(-)-Bay K 8644-induced contractions of rings were fully reverted by H-89. In conclusion, these results indicate that H-89 inhibited vascular I Ca1.2 and, consequently, the contractile function through a PKA-independent mechanism. Therefore, caution is recommended when interpreting experiments where H-89 is used to inhibit vascular smooth muscle PKA., (Copyright © 2017 Elsevier Inc. All rights reserved.)

A novel series of fused-benzensulfonamide 2-N-(pyrazol-3-yl)methylbenzo[d]isothiazole-1,1-dioxide derivatives was designed and synthesized as metabolically stable T-type calcium channel inhibitors. Several compounds, 9, 10, and 17, displayed potent T-type channel inhibitory activity. Among them, compounds 10 and 17 showed good metabolic stability in human liver microsomes, and low hERG channel and CYP450 inhibition. Compound 10 exhibited diabetic neuropathic pain-alleviating effects in a streptozotocin-induced peripheral diabetic neuropathy (PDN) model. The maximum efficacy of compound 10, which was 3-fold more potent than gabapentin, was observed at 1h after administration, and co-administration of compound 10 with gabapentin showed a considerable synergic effect., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

We isolated the novel vasoactive marine natural products, (5E,10E)-14-hydroxy-2,6,10-trimethylpentadeca-5,10-dien-4-one (4) and sargachromenol D (5), from Sargassum siliquastrum collected from the coast of the East Sea in South Korea by using activity-guided HPLC purification. The compounds effectively dilated depolarization (50mMK + )-induced basilar artery contraction with EC 50 values of 3.52±0.42 and 1.62±0.63μM, respectively, but only sargachromenol D (5) showed a vasodilatory effect on endothelin-1 (ET-1)-induced basilar artery contraction (EC 50 =9.8±0.6μM). These results indicated that sargachromenol D (5) could act as a dual antagonist of l-type Ca 2+ channel and endothelin A/B 2 receptors. Moreover, sargachromenol D (5) lowered blood pressure in spontaneous hypertensive rats (SHRs) 2h after oral treatment at a dose of 80mg/kg dose and the effect was maintained for 24h. Based on our ex vivo and in vivo experiments, we propose that sargachromenol D (5) is a strong candidate for the treatment of hypertension that is not controlled by conventional drugs, in particular, severe-, type II diabetes-, salt-sensitive, and metabolic disease-induced hypertension., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

As a bioisosteric strategy to overcome the poor metabolic stability of lead compound KYS05090S, a series of new fluoro-substituted 3,4-dihydroquinazoline derivatives was prepared and evaluated for T-type calcium channel (Ca v 3.2) block, cytotoxic effects and liver microsomal stability. Among them, compound 8h (KCP10068F) containing 4-fluorobenzyl amide and 4-cyclohexylphenyl ring potently blocked Ca v 3.2 currents (>90% inhibition) at 10μM concentration and exhibited cytotoxic effect (IC 50 =5.9μM) in A549 non-small cell lung cancer cells that was comparable to KYS05090S. Furthermore, 8h showed approximately a 2-fold increase in liver metabolic stability in rat and human species compared to KYS05090S. Based on these overall results, 8h (KCP10068F) may therefore represent a good backup compound for KYS05090S for further biological investigations as novel cytotoxic agent. In addition, compound 8g (KCP10067F) was found to partially protect from inflammatory pain via a blockade of Ca v 3.2 channels., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Aims: The aim of this study is to report on the hydrolytic action of Alcaligenes faecalis isolated from soil samples and its ability to degrade ochratoxin A., Methods and Results: An A. faecalis strain was identified and characterized by employing both a phenotypic analysis and 16S rDNA sequence analysis. The results show that this strain could degrade ochratoxin A efficiently but could not use it as a sole carbon source. Ochratoxin α was confirmed as a degradation product in the intracellular extract of A. faecalis using UPLC-MS/MS. Our results suggest that the biodegradation of ochratoxin A by the A. faecalis strain occurs through the hydrolysis of the ochratoxin A amide bond by a putative peptidase. This is the first report to date on the degradation of ochratoxin A by A. faecalis., Conclusion: The A. faecalis strain is presumably a suitable candidate for use in the biodegradation of ochratoxin A., Significance and Impact of the Study: Ochratoxin A, which is produced by some filamentous fungi, severely impacts human and animal health by contaminating several types of food and feed. Our study contributes to the identification of the function of A. faecalis 0D-1, which is capable of producing hydrolytic enzyme(s) to biodegrade ochratoxin A into nontoxic ochratoxin α, to minimize the risk associated with ochratoxin A exposure., (© 2017 The Society for Applied Microbiology.)