Dose-Response Activity-Based DNA-Encoded Library Screening

Dose-response, or "conforming" behavior, increases confidence in a screening hit's authenticity. Here, we demonstrate dose-response solid-phase DNA-encoded library (DEL) screening. Compound dose in microfluidic droplets is modulated via the UV intensity of photocleavage from DEL beads. A 55,296-member DEL was screened at different UV intensities against model enzyme drug targets factor Xa (FXa) and autotaxin (ATX). Both screens yielded photochemical dose-dependent hit rates (FXa hit rates of 0.08/0.05% at 100/30% UV exposure; ATX hit rates of 0.24/0.08% at 100/20% UV exposure). FXa hits contained structures reflective of FXa inhibitors and four hits inhibited FXa (IC50 = 4.2 ± 0.1, 7.4 ± 0.3, 9.0 ± 0.3, and 19 ± 2 μM.) The top ATX hits (two dihydrobenzamidazolones and a tetrahydroisoquinoline) were validated as inhibitors (IC50 = 7 ± 2, 13 ± 2, and 1 ± 0.3 μM). Photochemical dose-response DEL screening data prioritized hits for synthesis, the rate-limiting step in DEL lead identification.

Sterols and Triterpenes from Dobera glabra Growing in Saudi Arabia and Their Cytotoxic Activity

A new lupane caffeoyl ester, lup-20(29)-ene 3β-caffeate-30-al (7), and a new oleanane-type triterpene, 3β-hydroxyolean-13(18)-en-12-one (17), were isolated from the aerial parts of Dobera glabra (Forssk), along with ten known triterpenes, including seven lupane-type lupeol (1), 30-nor-lup-3β-ol-20-one (2), ∆1-lupenone (3), lup-20(29)-en-3β,30-diol (4), lupeol caffeate (5), 30-hydroxy lup-20(29)-ene 3β-caffeate (6), and betunaldehyde (8); three oleanane-type compounds were also identified, comprising δ-amyrone (15), δ-amyrin (16), and 11-oxo-β-amyrin (18); together with six sterols, comprising β-sitosterol (9), stigmasterol (10), 7α-hydroxy-β-sitosterol (11), 7α-hydroxy-stigmasterol (12), 7-keto-β-sitosterol (13), and 7-keto-stigmasterol (14). Their structures were elucidated using a variety of spectroscopic techniques, including 1D (1H, 13C, and DEPT-135 13C) and 2D (1H-1H COSY, 1H-13C HSQC, and 1H-13C HMBC) nuclear magnetic resonance (NMR) and accurate mass spectroscopy. Subsequently, the different plant extracts and some of the isolated compounds (1-9, 11 and 13) were investigated for their possible cytotoxic activity in comparison to cisplatin against a wide array of aggressive cancer cell lines, such as colorectal cancer (HCT-116), hepatocellular carcinoma (HepG-2), and prostate cancer (PC-3) cell lines. Compound 11 displayed broad cytotoxicity against all of the tested cell lines (IC50 ≅ 8 µg/mL in all cases), and a high safety margin against normal Vero cells (IC50 = 70 µg/mL), suggesting that 11 may be a highly selective and effective anticancer agent candidate. Notably, the evidence indicated that the mode of action of compound 11 could possibly consist of the inhibition of phosphodiesterase I (80.2% enzyme inhibition observed at 2 µM compound concentration).

Multiple Pathway-Mediated Gut-Modulatory Effects of Maerua subcordata (Gilg) DeWolf

BACKGROUND

Gastrointestinal disorders are often poorly managed, especially in developing countries, where there are limited resources and therapeutic options. Despite the rich diversity of medicinal plants that offer effective treatment options with fewer side effects, studies that provide scientific verification are lacking. Maerua subcordata (Gilg) DeWolf is among the plants claimed to have wide traditional medicine, use, including as a remedy against gastrointestinal problems. Therefore, this work aimed to evaluate the gut-modulatory effects of a crude leaf extract of M. subcordata (MSL.Cr), as well as its possible mechanism of action.

METHODS

A castor oil (10 mL/kg)-induced diarrheal mouse model was used to evaluate the antidiarrheal effect of MSL.Cr, and the spasmodic/antispasmodic effect of the extract was assessed using isolated rabbit jejunum with and without addition of standard cholinergic agonists/antagonists to predict the possible mechanism of action.

RESULTS

MSL.Cr exhibited 40% and 80% protection against castor oil-induced diarrhea in mice at doses of 500 and 1,000 mg/kg, respectively. In isolated rabbit jejunum, the extract increased spontaneous contractions at low doses (0.01-0.1 mg/mL), and was sensitive to atropine, whereas it showed complete inhibition at higher doses (0.3-1 mg/mL). It was shown that the relaxant effect was possibly mediated by the involvement of phosphodiesterase-enzyme inhibition and K+-channel activation. The extract potentiated the control concentration-response curve of carbachol, shifting it to the left, similarly to the control drug papaverine. The potassium-channel opening-like activity of MSL.Cr was possibly mediated by the involvement of aspecific K+-channels inhibition, since tetraethylammonium, anunselective antagonist of K+ channels, significantly reversed its inhibitory effect.

CONCLUSION

This study showed that the M. subcordata leaf extract demonstrated gut-modulatory effects, possibly mediated by a combination of muscarinic-receptor stimulation, phosphodiesterase inhibition, and aspecific K+-channel activation.

DRM02, a novel phosphodiesterase-4 inhibitor with cutaneous anti-inflammatory activity

Chronic inflammatory skin disorders are frequently associated with impaired skin barrier function. Selective phosphodiesterase-4 (PDE4) inhibition constitutes an effective therapeutic strategy for the treatment of inflammatory skin diseases. We now report the pharmacological anti-inflammatory profile of DRM02, a novel pyrazolylbenzothiazole derivative with selective in vitro inhibitory activity toward PDE4 isoforms A, B and D. DRM02 treatment of cultured primary human and mouse epidermal keratinocytes interfered with pro-inflammatory cytokine production elicited by interleukin-1α and tumor necrosis factor-α. Similarly, DRM02 inhibited the production of pro-inflammatory cytokines by human peripheral blood mononuclear cells ex vivo and cultured THP-1 monocyte-like cells, with IC₅₀ values of 0.6-14 µM. These anti-inflammatory properties of DRM02 were associated with dose-dependent repression of nuclear factor-κB (NF-κB) transcriptional activity. In skin inflammation in vivo mouse models, topically applied DRM02 inhibited the acute response to phorbol ester and induced Th2-type contact hypersensitivity reactivity. Further, DRM02 also decreased cutaneous clinical changes and expression of Th17 immune pathway cytokines in a mouse model of psoriasis evoked by repeated topical imiquimod application. Thus, the overall pharmacological profiling of the PDE4 inhibitor DRM02 has revealed its potential as a topical therapy for inflammatory skin disorders and restoration of skin homeostasis.

Cardiac Versus Renal Response to Volume Expansion in Preclinical Systolic Dysfunction With PDEV Inhibition and BNP

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In preclinical systolic dysfunction, defined as left ventricular systolic dysfunction with no heart failure signs or symptoms, impairment in cardiorenal response to volume expansion may lead to symptomatic heart failure. Rescue of this impaired process in preclinical disease may prevent development of symptomatic heart failure.

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In preclinical systolic dysfunction, inhibition of phosphodiesterase-V in combination with exogenous B-type natriuretic peptide administration results in improved cardiac function but worsened renal function in response to acute volume expansion.

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Future studies are needed to further define the physiological effects and long-term outcomes of phosphodiesterase-V inhibition and exogenous BNP administration. Understanding the cardiorenal effects and outcomes of combination phosphodiesterase-V with exogenous B-type natriuretic peptide may affect the clinical management of patients with preclinical systolic dysfunction and renal dysfunction.

Impaired cardiorenal response to acute saline volume expansion in preclinical systolic dysfunction (PSD) may lead to symptomatic heart failure. The objective was to determine if combination phosphodiesterase-V inhibition and exogenous B-type natriuretic peptide (BNP) administration may enhance cardiorenal response. A randomized double-blinded, placebo-controlled study was conducted in 21 subjects with PSD and renal dysfunction. Pre-treatment with tadalafil and subcutaneous BNP resulted in improved cardiac function, as evidenced by improvement in ejection fraction, left atrial volume index, and left ventricular end-diastolic volume. However, there was reduced renal response with reduction in renal plasma flow, glomerular filtration rate, and urine flow. (Tadalafil and Nesiritide as Therapy in Pre-clinical Heart Failure; NCT01544998)

Design, Synthesis, Pharmacological Evaluation and Vascular Effects of Delphinidin Analogues

BACKGROUND

Among polyphenolic compounds suggested to prevent cardiovascular diseases (CVDs) and to explain the "French paradox", the anthocyanidin delphinidin (Dp) has been reported to support at least partly the vascular beneficial effects of dietary polyphenolic compounds including those from fruits and related products as red wine. It has also been highlighted that Dp interacts directly with the active site of estrogen receptor α (ERα), leading to activation of endothelial NO synthase (eNOS) pathway thus contributing to the prevention of endothelial dysfunction in mice aorta. However, anthocyanidins have very low bioavailability and despite a well described in vitro efficacy, the very high hydrophilicity and physicochemical instability of Dp might explain the lack of in vivo reported effects.

OBJECTIVE

The aim of this study was to identify new Dp analogues with increased lipophilicity and vasorelaxation potential by a chemical modulation of its structure and to characterize the signaling pathway notably in relation with ERα signaling and nitric oxide (NO) production.

METHOD

OCH3-substituted delphinidin analogues were obtained through the coupling of the corresponding acetophenones with substituted benzaldehydes. Prediction of resorption of the flavylium derivatives was performed with the calculated logP and induction of vasorelaxation was performed by myography on WT and ERαKO mice thoracic aorta rings and compared to Dp. NO production was evaluated in vitro on human primary endothelial cells.

RESULTS

Eight Dp analogues were synthesized including four new flavylium derivatives. Two compounds (9 and 11) showed a strong increase of vasorelaxation potential and a theoretically increased bioavailability compared to Dp. Interestingly, 9 and 11 induced increased O2 - or NO endothelial production respectively and revealed a novel NO-dependent ERα-independent relaxation compared to Dp. We suggested that this mechanism may be at least in part supported by the inhibition of vascular cyclic nucleotide phosphodiesterase (PDEs).

CONCLUSION

The current study demonstrated that pharmacomodulation of the Dp backbone by replacement of OH groups by OCH3 groups of the A and B rings led to the identification and characterization of two compounds (9 and 11) with enhanced physio-chemical properties that could be associated to higher permeability capability and pharmacological activity for the prevention of CVDs compared to Dp.

Impaired neuronal nitric oxide synthase-mediated vasodilator responses to mental stress in essential hypertension

Neuronal NO synthase (nNOS) regulates blood flow in resistance vasculature at rest and during mental stress. To investigate whether nNOS signaling is dysfunctional in essential hypertension, forearm blood flow responses to mental stress were examined in 88 subjects: 48 with essential hypertension (42±14 years; blood pressure, 141±17/85±15 mm Hg; mean±SD) and 40 normotensive controls (38±14 years; 117±13/74±9 mm Hg). A subsample of 34 subjects (17 hypertensive) participated in a single blind 2-phase crossover study, in which placebo or sildenafil 50 mg PO was administered before an intrabrachial artery infusion of the selective nNOS inhibitor S-methyl-l-thiocitrulline (SMTC, 0.05, 0.1, and 0.2 μmol/min) at rest and during mental stress. In a further subsample (n=21) with an impaired blood flow response to mental stress, responses were measured in the presence and absence of the α-adrenergic antagonist phentolamine. The blood flow response to mental stress was impaired in hypertensive compared with normotensive subjects (37±7% versus 70±8% increase over baseline; P<0.001). SMTC blunted responses to mental stress in normotensive but not in hypertensive subjects (reduction of 40±11% versus 3.0±14%, respectively, P=0.01, between groups). Sildenafil reduced the blood flow response to stress in normotensive subjects from 89±14% to 43±14% (P<0.03) but had no significant effect in hypertensive subjects. Phentolamine augmented impaired blood flow responses to mental stress from 39±8% to 67±13% (P<0.02). Essential hypertension is associated with impaired mental stress-induced nNOS-mediated vasodilator responses; this may relate to increased sympathetic outflow in hypertension. nNOS dysfunction may impair vascular homeostasis in essential hypertension and contribute to stress-induced cardiovascular events.

Targets for future clinical trials in Huntington's disease: what's in the pipeline?

The known genetic cause of Huntington's disease (HD) has fueled considerable progress in understanding its pathobiology and the development of therapeutic approaches aimed at correcting specific changes linked to the causative mutation. Among the most promising is reducing expression of mutant huntingtin protein (mHTT) with RNA interference or antisense oligonucleotides; human trials are now being planned. Zinc-finger transcriptional repression is another innovative method to reduce mHTT expression. Modulation of mHTT phosphorylation, chaperone upregulation, and autophagy enhancement represent attempts to alter cellular homeostasis to favor removal of mHTT. Inhibition of histone deacetylases (HDACs) remains of interest; recent work affirms HDAC4 as a target but questions the assumed centrality of its catalytic activity in HD. Phosphodiesterase inhibition, aimed at restoring synaptic function, has progressed rapidly to human trials. Deranged cellular signaling provides several tractable targets, but specificity and complexity are challenges. Restoring neurotrophic support in HD remains a key potential therapeutic approach. with several approaches being pursued, including brain-derived neurotrophic factor (BDNF) mimesis through tyrosine receptor kinase B (TrkB) agonism and monoclonal antibodies. An increasing understanding of the role of glial cells in HD has led to several new therapeutic avenues, including kynurenine monooxygenase inhibition, immunomodulation by laquinimod, CB2 agonism, and others. The complex metabolic derangements in HD remain under study, but no clear therapeutic strategy has yet emerged. We conclude that many exciting therapeutics are progressing through the development pipeline, and combining a better understanding of HD biology in human patients, with concerted medicinal chemistry efforts, will be crucial for bringing about an era of effective therapies.

A prospective assessment of the effect of aminophylline therapy on urine output and inflammation in critically ill children

BACKGROUND

Aminophylline, an established bronchodilator, is also purported to be an effective diuretic and anti-inflammatory agent. However, the data to support these contentions are scant. We conducted a prospective, open-label, single arm, single center study to assess the hypothesis that aminophylline increases urine output and decreases inflammation in critically ill children.

METHODS

Children less than 18 years of age admitted to the pediatric intensive care unit who were prescribed aminophylline over a 24-h period were eligible for study. The use and dosing of aminophylline was independent of the study and was at the discretion of the clinical team. Data analyzed consisted of demographics, diagnoses, medications, and markers of pulmonary function, renal function, and inflammation. Data were collected at baseline and at 24-h after aminophylline initiation with primary outcomes of change in urine output and inflammatory cytokine concentrations.

RESULTS

Thirty-five patients were studied. Urine output increased significantly with aminophylline use [median increase 0.5 mL/kg/h (IQR: -0.3, 1.3), p = 0.05] while blood urea nitrogen and creatinine concentrations remained unchanged. Among patients with elevated C-reactive protein concentrations, levels of both interleukin-6 (IL-6) and IL-10 decreased at 24 h of aminophylline therapy. There were no significant differences in pulmonary compliance or resistance among patients invasively ventilated at both time points. Side effects of aminophylline were detected in 7 of 35 patients.

CONCLUSION

Although no definitive conclusions can be drawn from this study, aminophylline may be a useful diuretic and effective anti-inflammatory medication in critically ill children. Given the incidence of side effects, the small sample size and the uncontrolled study design, further study is needed to inform the appropriate use of aminophylline in these children.

Discovery of colon tumor cell growth inhibitory agents through a combinatorial approach

Two series with the general formula of 4,6-diaryl-2-oxo-1,2 dihydropyridine-3-carbonitriles and their isosteric 4,6-diaryl-2-imino-1,2-dihydropyridine-3-carbonitrile were synthesized through one pot reaction of the appropriate acetophenone, aldehyde, ammonium acetate with ethyl cyanoacetate or malononitrile, respectively. The synthesized compounds were evaluated for their tumor cell growth inhibitory activity against the human HT-29 colon tumor cell line, as well as their PDE3 inhibitory activity. Compound 4-(2-Ethoxyphenyl)-2-oxo-6-thiophen-3-yl-1,2-dihydropyridine-3 carbonitrile (21) showed tumor cell growth inhibitory activity with an IC50 value of 1.25 microM. Meanwhile, 4-(4-Ethoxyphenyl)-2-imino-6-(thiophen-3-yl)-1,2-dihydropyridine-3-carbonitrile (26) showed inhibitory effect upon PDE3 using cAMP or cGMP as substrate. No correlation exists between PDE3 inhibition and the tumor cell growth inhibitory activity. Docking compound 21 to other possible molecular targets showed the potential to bind PIM1 Kinase.

Effect of theophylline and specific phosphodiesterase IV inhibition on proliferation and apoptosis of progenitor cells in bronchial asthma

1. Theophylline possesses anti-inflammatory activities in asthma. We examined whether theophylline and agents that modulate cyclic AMP can determine the survival and proliferation of progenitor cells. 2. Progenitor cells from the blood of normal and asthmatic subjects were cultured for 14 days in methylcellulose with GM-CSF, stem cell factor, IL-3 and IL-5. Apoptosis was measured by flow cytometry of propidium-iodide-stained cells. 3. A greater number of colonies with a higher proportion of cells of eosinophil lineage from asthmatics compared to normal subjects were grown. Theophylline (at 5 and 20 micro g ml(-1)) significantly inhibited colony formation and increased apoptotic cells in asthmatics compared to control. Salbutamol (0.1, 1, 10 micro M), dibutyryl-cAMP (0.1, 1 mM) and rolipram (0.1, 1 mM), a phosphodiesterase IV inhibitor, also dose-dependently decreased colony numbers and increased apoptosis of progenitor cells from asthmatics. 4. There was no significant effect of theophylline, db-cAMP, salbutamol or rolipram on colony formation or the survival of progenitor cells from normal subjects. AMP did not affect the colony formation and apoptosis. Expression of Bcl-2 protein on progenitor cells of asthma was downregulated by theophylline, salbutamol, db-cAMP and rolipram. 5. Theophylline and rolipram decreased colony formation committed to the eosinophil lineage, together with an increase in apoptosis through an inhibition of Bcl-2 expression effects that may occur through cAMP. The anti-inflammatory properties of theophylline include an inhibition of circulating progenitor cells.

Cardiovascular effects of the novel Ca2+-sensitiser EMD 57033 in pigs at rest and during treadmill exercise

1. To date no study has described the cardiovascular effects of increased myofilament Ca2+ responsiveness in awake animals both under resting conditions and during treadmill exercise. In the present study we therefore investigated the systemic, pulmonary and coronary haemodynamic actions of the Ca2+ sensitizer EMD 57033 in 16 chronically instrumented awake pigs at rest and during treadmill exercise, and compared these to the haemodynamic actions of the Ca2+ sensitizer/phosphodiesterase inhibitor pimobendan. 2. Under resting conditions EMD 57033 (0.2, 0.4 and 0.8 mg kg(-1) min(-1), i.v.) produced dose-dependent increases in LVdP/dt(max) (up to 65+/-17% (mean+/-s.e.mean), P < or = 0.05) and stroke volume (up to 20+/-3%, P < or = 0.05), with an increase in heart rate only after the highest dose (22+/-5%, P < or = 0.05), while mean aortic blood pressure and LVdP/dt(min) were not altered. EMD 57033 had also no effect on pulmonary vascular resistance, but produced dose-dependent decreases in systemic vascular resistance (32+/-4%, P < or = 0.05), and coronary vascular resistance (44+/-2%, P < or = 0.05). These effects were essentially unchanged when animals were pretreated with non-selective beta-adrenoceptor blockade, indicating that phosphodiesterase inhibition did not contribute to the positive inotropic actions of EMD 57033. 3. During exercise at 2, 3, and 4 km h(-1), the positive inotropic actions of EMD 57033 gradually waned at higher levels of exercise. This may have been caused by the exercise-induced increase in beta-adrenergic activity, because after pretreatment with propranolol the positive inotropic actions of EMD 57033 were preserved at all levels of exercise. In contrast, the positive inotropic and chronotropic effects of pimobendan were amplified during exercise, but were abolished (at rest) or markedly attenuated (during exercise) after pretreatment with propranolol. 4. The responses to EMD 57033 during exercise after combined alpha- and beta-adrenergic receptor blockade were not different from those after beta-adrenergic receptor blockade alone, indicating that the positive inotropic actions of EMD 57033 were not mediated via or did not depend on intact alpha-adrenergic receptor activity. 5. In conclusion, EMD 57033 increases left ventricular myocardial contractility in awake pigs. During exercise this effect is partially offset by the increased beta-adrenergic activity, with no effect of alpha-adrenergic activity, suggesting that EMD 57033 may be most effective in patients with severe loss of beta-adrenergic responsiveness.