Nitric Oxide Releasing Delivery Platforms: Design, Detection, Biomedical Applications, and Future Possibilities.

Gasotransmitters belong to the subfamily of endogenous gaseous signaling molecules, which find a wide range of biomedical applications. Among the various gasotransmitters, nitric oxide (NO) has an enormous effect on the cardiovascular system. Apart from this, NO showed a pivotal role in neurological, respiratory, and immunological systems. Moreover, the paradoxical concentration-dependent activities make this gaseous signaling molecule more interesting. The gaseous NO has negligible stability in physiological conditions (37 °C, pH 7.4), which restricts their potential therapeutic applications. To overcome this issue, various NO delivering carriers were reported so far. Unfortunately, most of these NO donors have low stability, short half-life, or low NO payload. Herein, we review the synthesis of NO delivering motifs, development of macromolecular NO donors, their advantages/disadvantages, and biological applications. Various NO detection analytical techniques are discussed briefly, and finally, a viewpoint about the design of polymeric NO donors with improved physicochemical characteristics is predicted.

Nanoencapsulated hybrid compound SA-2 with long-lasting intraocular pressure-lowering activity in rodent eyes.

Purpose: Glaucoma is a neurodegenerative disease of the eye with an estimated prevalence of more than 111.8 million patients worldwide by 2040, with at least 6 to 8 million projected to become bilaterally blind. Clinically, the current method of slowing glaucomatous vision loss is to reduce intraocular pressure (IOP). In this manuscript, we describe the in vitro cytoprotective and in vivo long lasting IOP-lowering activity of the poly D, L-lactic-co-glycolic acid (PLGA) nanoparticle-encapsulated hybrid compound SA-2, possessing nitric oxide (NO) donating and superoxide radical scavenging functionalities. Methods: Previously characterized primary human trabecular meshwork (hTM) cells were used for the study. hTM cells were treated with SA-2 (100 µM, 200 µM, and 1,000 µM), SA-2 PLGA-loaded nanosuspension (SA-2 NPs, 0.1%), or vehicle for 30 min. Cyclic guanosine monophosphate (cGMP) and super oxide dismutase (SOD) levels were analyzed using commercial kits. In another experiment, hTM cells were pretreated with tert-butyl hydrogen peroxide (TBHP, 300 µM) for 30 min followed by treatment with escalating doses of SA-2 for 24 h, and CellTiter 96 cell proliferation assay was performed. For the biodistribution study, the cornea, aqueous humor, vitreous humor, retina, choroid, and sclera were collected after 1 h of administration of a single eye drop (30 µl) of SA-2 NPs (1% w/v) formulated in PBS to rat (n = 6) eyes. Compound SA-2 was quantified using high performance liquid chromatography /mass spectrometry (HPLC/MS). For the IOP-lowering activity study, a single SA-2 NPs (1%) eye drop was instilled in normotensive rats eyes and in the IOP-elevated rat eyes (n = 3/group, in the Morrison model of glaucoma), or Ad5TGFß2-induced ocular hypertensive (OHT) mouse eyes (n = 5/group). IOP was measured at various time points up to 72 h, and the experiment was repeated in triplicate. Mouse aqueous humor outflow facility was determined with multiple flow-rate infusion and episcleral venous pressure estimated with manometry. Results: SA-2 upregulated cGMP levels (six- to ten-fold) with an half maximal effective concentration (EC50) of 20.3 µM in the hTM cells and simultaneously upregulated (40-fold) the SOD enzyme when compared with the vehicle-treated hTM cells. SA-2 also protected hTM cells from TBHP-induced decrease in cell survival with an EC50 of 0.38 µM. A single dose of slow-release SA-2 NPs (1% w/v) delivered as an eye drop significantly lowered IOP (by 30%) in normotensive and OHT rodent eyes after 3 h post-dose, with the effect lasting up to 72 h. A statistically significant increase in aqueous outflow facility and a decrease in episcleral venous pressure was observed in rodents at this dose at 54 h. Conclusions: Hybrid compound SA-2 upregulated cGMP in hTM cells, increased outflow facility and decreased IOP in rodent models of OHT. Compound SA-2 possessing an antioxidant moiety provided additive cytoprotective activity to oxidatively stressed hTM cells by scavenging reactive oxygen species (ROS) and increasing SOD enzyme activity. Additionally, the PLGA nanosuspension formulation (SA-2 NPs) provided longer duration of IOP-lowering activity (up to 3 days) in comparison with the free non-encapsulated SA-2 drug. The data have implications for developing novel, non-prostaglandin therapeutics for IOP-lowering and cytoprotective effects with the possibility of an eye drop dosing regimen of once every 3 days for patients with glaucoma.

A turn-on and lysosome-targeted fluorescent NO releaser in water media and its application in living cells and zebrafishes.

Due to the high activity and difficult to transport of nitric oxide, the controlled release of nitric oxide has been a new trend in the research on the biological effect of nitric oxide. In this paper, a water-soluble and turn-on fluorescent NO donor Rh-NO was synthesized. Upon 525 nm irradiation, the fluorescence of the Rh-NO at 568 nm enhanced with the quantum yield (ΦF) of Rh-NO changing from 5.08% to 35.96%. The mechanism of NO releasing was proved by HRMS and the Dan. The releasing time of 6 min and the releasing yield of 0.61 proved the superiority of Rh-NO. Excellent cell activity above 80% of Rh-NO and Rh guaranteed that nitric oxide was released from Rh-NO in lysosome and zebrafishes successfully, which provided a good platform to understand the biological effects of nitric oxide in lysosomes.

Effects of nitric oxide-releasing nanoparticles on neotropical tree seedlings submitted to acclimation under full sun in the nursery.

Polymeric nanoparticles have emerged as carrier systems for molecules that release nitric oxide (NO), a free radical involved in plant stress responses. However, to date, nanoencapsulated NO donors have not been applied to plants under realistic field conditions. Here, we verified the effects of free and nanoencapsulated NO donor, S-nitroso-mercaptosuccinic acid (S-nitroso-MSA), on growth, physiological and biochemical parameters of neotropical tree seedlings kept under full sunlight in the nursery for acclimation. S-nitroso-MSA incorporation into chitosan nanoparticles partially protected the NO donor from thermal and photochemical degradation. The application of nanoencapsulated S-nitroso-MSA in the substrate favoured the growth of seedlings of Heliocarpus popayanensis, a shade-intolerant tree. In contrast, free S-nitroso-MSA or nanoparticles containing non-nitrosated mercaptosuccinic acid reduced photosynthesis and seedling growth. Seedlings of Cariniana estrellensis, a shade-tolerant tree, did not have their photosynthesis and growth affected by any formulations, despite the increase of foliar S-nitrosothiol levels mainly induced by S-nitroso-MSA-loaded nanoparticles. These results suggest that depending on the tree species, nanoencapsulated NO donors can be used to improve seedling acclimation in the nursery.

Hybrid Compound SA-2 is Neuroprotective in Animal Models of Retinal Ganglion Cell Death.

Purpose: Determine the toxicity, bioavailability in the retina, and neuroprotective effects of a hybrid antioxidant-nitric oxide donor compound SA-2 against oxidative stress-induced retinal ganglion cell (RGC) death in neurodegenerative animal models. Methods: Optic nerve crush (ONC) and ischemia reperfusion (I/R) injury models were used in 12-week-old C57BL/6J mice to mimic conditions of glaucomatous neurodegeneration. Mice were treated intravitreally with either vehicle or SA-2. Retinal thickness was measured by spectral-domain optical coherence tomography (SD-OCT). The electroretinogram and pattern ERG (PERG) were used to assess retinal function. RGC survival was determined by counting RBPMS-positive RGCs and immunohistochemical analysis of superoxide dismutase 1 (SOD1) levels was carried out in the retina sections. Concentrations of SA-2 in the retina and choroid were determined using HPLC and MS. In addition, the direct effect of SA-2 treatment on RGC survival was assessed in ex vivo rat retinal explants under hypoxic (0.5% O2) conditions. Results: Compound SA-2 did not induce any appreciable change in retinal thickness, or in a- or b-wave amplitude in naive animals. SA-2 was found to be bioavailable in both the retina and choroid after a single intravitreal injection (2% wt/vol). An increase in SOD1 levels in the retina of mice subjected to ONC and SA-2 treatment, suggests an enhancement in antioxidant activity. SA-2 provided significant (P < 0.05) RGC protection in all three of the tested RGC injury models in rodents. PERG amplitudes were significantly higher in both I/R and ONC mouse eyes following SA-2 treatment (P ≤ 0.001) in comparison with the vehicle and control groups. Conclusions: Compound SA-2 was effective in preventing RGC death and loss of function in three different rodent models of acute RGC injury: ONC, I/R, and hypoxia.

A Phase 1 Randomized Study of Single Intravenous Infusions of the Novel Nitroxyl Donor BMS-986231 in Healthy Volunteers.

Nitroxyl (HNO) is a reactive nitrogen molecule that has potential therapeutic benefits for patients with acute heart failure. The results of the first-in-human study for BMS-986231, a novel HNO donor, are reported. The aim of this sequential cohort study was to evaluate the safety, tolerability, and pharmacokinetic profile of BMS-986231 after 24- and 48-hour intravenous infusions in healthy volunteers. Eighty subjects were randomized and dosed. Seven cohorts (stratum A) received BMS-986231 0.1, 0.33, 1, 3, 5, 10, and 15 µg/kg/min or placebo, infused over 24 hours. An additional cohort (stratum B) received 10 µg/kg/min or placebo, infused over 48 hours. Adverse events (AEs) were reported for 30 days after completion of infusion. Blood/urine samples were collected at regular intervals; other parameters (blood pressure, heart rate/rhythm, cardiac index) were also assessed. Headaches were the most commonly reported drug-related AE (48%) in those who received BMS-986231, although their severity was reduced by hydration. No other significant drug-related AEs were noted. BMS-986231 was associated with dose-dependent and well-tolerated reductions in systolic and diastolic blood pressure versus baseline; cardiac index, as measured noninvasively, was increased. BMS-986231 had no clinically significant effect on heart rate/rhythm or laboratory parameters. Its mean elimination half-life was 0.7-2.5 hours. BMS-986231 was safe and well-tolerated for up to 24 hours (15 µg/kg/min) or 48 hours (10 µg/kg/min), with a favorable hemodynamic profile observed. Ongoing studies continue to evaluate the potential benefit of BMS-986231 in patients with acute heart failure.

Glutathione Responsive ß-Cyclodextrin Conjugated S-Nitrothiols as a Carrier for Intracellular Delivery of Nitric Oxide.

Nitric oxide (NO) exerts multiple functions in many life processes and was of great significance in a variety of biomedical scenarios. However, the mismatches between releasing locations and NO active sites seriously limited the available NO at areas of interest and greatly dampen the overall efficiency of delivery systems. Therefore, in the present study, a NO donor was developed to achieve intracellular delivery and release of NO to overcome the aforementioned challenges. Enhanced uptake and effective intracellular release of NO were realized via ß-cyclodextrin (ß-CD) mediated endocytosis and high level glutathione (GSH) inside cells, respectively. We demonstrated that intracellularly delivered NO would exert stronger bioeffects than premature release of NO outside targeted cells. Besides, ß-CD assisted cellular uptake proved indispensable in maximizing the influence of NO in modulating cellular behavior. These results demonstrated the significance of intracellular delivery and release of NO in improving its bioutilization. The carrier could efficiently inhibit proliferation of SMCs, while promoting the growth of ECs. Such cell-type-differed physiological effects were advantageous in re-endothelialization and might hold great potential in cardiovascular applications.

Pharmacokinetics and pharmacodynamics of nitric oxide mimetic agents.

Drug discovery focusing on NO mimetics has been hamstrung due to its unconventional nature. Central to these challenges is the fact that direct measurement of molecular NO in biological systems is exceedingly difficulty. Hence, drug development of NO mimetics must rely upon measurement of the NO donating specie (i.e., a prodrug) and a downstream marker of efficacy without directly measuring the molecule, NO, that is responsible for biological effect. The focus of this review is to catalog in vivo attempts to monitor the pharmacokinetics (PK) of the NO donating specie and the pharmacodynamic (PD) readout of NO bioactivity.

Winner of the society for biomaterials young investigator award for the annual meeting of the society for biomaterials, April 11-14, 2018, Atlanta, GA: S-nitrosated poly(propylene sulfide) nanoparticles for enhanced nitric oxide delivery to lymphatic tissues.

Nitric oxide (NO) is a therapeutic implicated for the treatment of diseases afflicting lymphatic tissues, which range from infectious and cardiovascular diseases to cancer. Existing technologies available for NO therapy, however, provide poor bioactivity within lymphatic tissues. In this work, we address this technology gap with a NO encapsulation and delivery strategy leveraging the formation of S-nitrosothiols on lymphatic-targeting pluronic-stabilized, poly(propylene sulfide)-core nanoparticles (SNO-NP). We evaluated in vivo the lymphatic versus systemic delivery of NO resulting from intradermal administration of SNO-NP benchmarked against a commonly used, commercially available small molecule S-nitrosothiol NO donor, examined signs of toxicity systemically as well as localized to the site of injection, and investigated SNO effects on lymphatic transport and NP uptake by lymph node (LN)-resident cells. Donation of NO from SNO-NP, which scaled in proportion to the total administered dose, enhanced LN accumulation by two orders of magnitude without substantially reducing lymphatic transport of NP or the viability and extent of NP uptake by LN-resident cells. Additionally, NO delivery by SNO-NP was accompanied by low-to-negligible NO accumulation in systemic tissues with no apparent inflammation. These results suggest the utility and selectivity of SNO-NP for the targeted treatment of NO-regulated diseases that afflict lymphatic tissues. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 1463-1475, 2018.

A Phase 2a dose-escalation study of the safety, tolerability, pharmacokinetics and haemodynamic effects of BMS-986231 in hospitalized patients with heart failure with reduced ejection fraction.

AIMS: This study was designed to evaluate the safety, tolerability and haemodynamic effects of BMS-986231, a novel second-generation nitroxyl donor with potential inotropic, lusitropic and vasodilatory effects in patients hospitalized with decompensated heart failure and reduced ejection fraction (HFrEF). METHODS AND RESULTS: Forty-six patients hospitalized with decompensated HFrEF were enrolled into four sequential dose-escalation cohorts in this double-blind, randomized, placebo-controlled Phase 2a study. Patients with baseline pulmonary capillary wedge pressure (PCWP) of ≥20 mmHg and a cardiac index of ≤2.5 L/min/m2 received one 6-h i.v. infusion of BMS-986231 (at 3, 5, 7 or 12 µg/kg/min) or placebo. BMS-986231 produced rapid and sustained reductions in PCWP, as well as consistent reductions in time-averaged pulmonary arterial systolic pressure, pulmonary arterial diastolic pressure and right atrial pressure. BMS-986231 increased non-invasively measured time-averaged stroke volume index, cardiac index and cardiac power index values, and decreased total peripheral vascular resistance. There was no evidence of increased heart rate, drug-related arrhythmia or symptomatic hypotension with BMS-986231. Analyses of adverse events throughout the 30-day follow-up did not identify any toxicities specific to BMS-986231, with the potential exception of infrequent mild-to-moderate headaches during infusion. There were no treatment-related serious adverse events. CONCLUSIONS: BMS-986231 demonstrated a favourable safety and haemodynamic profile in patients hospitalized with advanced heart failure. Based on preclinical data and these study's findings, it is possible that the haemodynamic benefits may be mediated by inotropic and/or lusitropic as well as vasodilatory effects. The therapeutic potential of BMS-986231 should be further assessed in patients with heart failure.

Molecular Hybridization Tools in the Development of Furoxan-Based NO-Donor Prodrugs.

The molecular hybridization of different compounds with known pharmacological activity is a particularly prominent approach for the design of potential drugs with improved pharmacokinetic profiles. Much attention over the last decade has been focused on the synthesis of hybrid structures with a nitric oxide (NO)-donor framework, as NO is a ubiquitous and crucial regulator of cellular metabolism, affecting various physiological and pathophysiological processes. 1,2,5-Oxadiazole 2-oxides (furoxans), which are capable of exogenous NO release in the presence of thiol cofactors, are an important class of prospective NO donors. As such, a wide range of hybrid compounds that combine a furoxan ring with various pharmacologically active structures have been created. This review focuses on recent results in the synthesis and pharmacological activity of furoxan-based hybrids. Special attention is given to chemo- and regioselective methods used in the preparation of these hybrid structures, and the role of synergistic effects on their pharmacological activity, associated with the furoxan fragment.

Differential effects of liver steatosis on pharmacokinetic profile of two closely related hepatoselective NO-donors; V-PYRRO/NO and V-PROLI/NO.

PURPOSE: To analyze the effect of liver steatosis and obesity on pharmacokinetic profile of two structurally-related liver-selective NO-donors - V-PYRRO/NO and V-PROLI/NO. METHODS: C57BL/6 mice were fed control or high-fat diet for 15 weeks to induced liver steatosis and obesity (HFD mice). Pharmacokinetics and renal elimination studies were conducted in vivo following iv dosing of V-PYRRO/NO and V-PROLI/NO (0.03mmol/kg). Hepatic clearance was evaluated ex vivo in the isolated perfused mice liver and in vitro with the use of liver microsomes. RESULTS: V-PYRRO/NO and V-PROLI/NO, despite similar structure, displayed different pharmacokinetic properties. V-PYRRO/NO was uptaken and metabolized by the liver, while V-PROLI/NO was eliminated unchanged with urine. In HFD mice, despite increased CYP450 metabolism of V-PYRRO/NO the elimination rate was slower most likely due to the impairment of hepatic microcirculation caused by liver fat accumulation. In turn, in HFD mice renal clearence of V-PROLI/NO was accelerated and volume of distribution was increased most likely due to additional intracellular water in HFD mice. CONCLUSIONS: The pharmacokinetics of V-PROLI/NO, the novel proline-based analog of V-PYRRO/NO with additional single carboxylic acid moiety, attached to the molecule of V-PYRRO/NO to improve the water solubility, was differently affected by liver steatosis and obesity as compared with the parent compound V-PYRRO/NO.

Hypotensive Effect and Accumulation of Dinitrosyl Iron Complexes in Blood and Tissues after Intravenous and Subcutaneous Injection.

Subcutaneous injection of Oxacom with glutathione-bound dinitrosyl iron complex as the active principle produced a slower drop of mean BP and longer accumulation of protein-bound dinitrosyl iron complexes in whole blood and tissues than intravenous injection of this drug, while durations of hypotensive effect in both cases were practically identical. In contrast to intravenous injection of the drug, its subcutaneous administration was not characterized by a high concentration of protein-bound dinitrosyl iron complexes in the blood at the onset of experiment; in addition, accumulation of these NO forms in the lungs was more pronounced after subcutaneous injection than after intravenous one.

Intraocular Pressure-Lowering Activity of NCX 470, a Novel Nitric Oxide-Donating Bimatoprost in Preclinical Models.

PURPOSE: The prostaglandin F2alpha (PGF2α) analogue bimatoprost lowers intraocular pressure (IOP) by increasing uveoscleral outflow at doses shown to elicit redness of the eye. With the aim to enhance the IOP-lowering effect of bimatoprost we studied NCX 470 [(S,E)-1-((1R,2R,3S,5R)-2-((Z)-7-(ethylamino)-7-oxohept-2-enyl)-3,5-dihydroxycyclopentyl)-5-phenylpent-1-en-3-yl 6-(nitrooxy)hexanoate], a dual-acting compound combining bimatoprost with nitric oxide (NO) known to mainly act via relaxation of trabecular meshwork and Schlemm's canal. METHODS: New Zealand white rabbits with transient hypertonic saline-induced IOP elevation (tOHT-rabbits), cynomolgus monkeys with laser-induced ocular hypertension (OHT-monkeys), and normotensive dogs (ONT-dogs) were used. The levels of NCX 470, bimatoprost, and bimatoprost acid were determined in aqueous humor (AH), cornea (CR), and iris/ciliary body (ICB) by liquid chromatography-mass spectrometry/mass (LC-MS/MS), while cGMP in AH and ICB was monitored using an enzyme immunoassay (EIA) kit in pigmented Dutch Belted rabbits. RESULTS: NCX 470 (0.14%, 30 µL) lowered IOP in tOHT-rabbits with an E(max) of -7.2 ± 2.8 mm Hg at 90 minutes. Bimatoprost at equimolar dose (0.1%, 30 µL) was noneffective in this model. NCX 470 (0.042%, 30 µL) was more effective than equimolar (0.03%, 30 µL) bimatoprost in ONT-dogs (IOP change, -5.4 ± 0.7 and -3.4 ± 0.7 mm Hg, respectively, P < 0.05) and in OHT-monkeys (IOP change, -7.7 ± 1.4 and -4.8 ± 1.7 mm Hg, respectively, P < 0.05) at 18 hours post dosing. NCX 470 (0.042%, 30 µL) or bimatoprost (0.03%, 30 µL) resulted in similar bimatoprost acid exposure in AH, CR, and ICB while cGMP was significantly increased in AH and ICB at 18 and 24 hours after NCX 470 dosing. CONCLUSIONS: NCX 470 lowers IOP more than equimolar bimatoprost in three animal models of glaucoma by activating PGF2α and NO/cGMP signaling pathways.

Naproxcinod shows significant advantages over naproxen in the mdx model of Duchenne Muscular Dystrophy.

BACKGROUND: In dystrophin-deficient muscles of Duchenne Muscular Dystrophy (DMD) patients and the mdx mouse model, nitric oxide (NO) signalling is impaired. Previous studies have shown that NO-donating drugs are beneficial in dystrophic mouse models. Recently, a long-term treatment (9 months) of mdx mice with naproxcinod, an NO-donating naproxen, has shown a significant improvement of the dystrophic phenotype with beneficial effects present throughout the disease progression. It remains however to be clearly dissected out which specific effects are due to the NO component compared with the anti-inflammatory activity associated with naproxen. Understanding the contribution of NO vs the anti-inflammatory effect is important, in view of the potential therapeutic perspective, and this is the final aim of this study. METHODS: Five-week-old mdx mice received either naproxcinod (30 mg/kg) or the equimolar dose of naproxen (20 mg/kg) in the diet for 6 months. Control mdx mice were used as reference. Treatments (or vehicle for control groups) were administered daily in the diet. For the first 3 months the study was performed in sedentary animals, then all mice were subjected to exercise until the sixth month. Skeletal muscle force was assessed by measuring whole body tension in sedentary animals as well as in exercised mice and resistance to fatigue was measured after 3 months of running exercise. At the end of 6 months of treatment, animals were sacrificed for histological analysis and measurement of naproxen levels in blood and skeletal muscle. RESULTS: Naproxcinod significantly ameliorated skeletal muscle force and resistance to fatigue in sedentary as well as in exercised mice, reduced inflammatory infiltrates and fibrosis deposition in both cardiac and diaphragm muscles. Conversely, the equimolar dose of naproxen showed no effects on fibrosis and improved muscle function only in sedentary mice, while the beneficial effects in exercised mice were lost demonstrating a limited and short-term effect. CONCLUSION: In conclusion, this study shows that NO donation may have an important role, in addition to anti-inflammatory activity, in slowing down the progression of the disease in the mdx mouse model therefore positioning naproxcinod as a promising candidate for treatment of DMD.

Hepatoselective Nitric Oxide (NO) Donors, V-PYRRO/NO and V-PROLI/NO, in Nonalcoholic Fatty Liver Disease: A Comparison of Antisteatotic Effects with the Biotransformation and Pharmacokinetics.

V-PYRRO/NO [O(2)-vinyl-1-(pyrrolidin-1-yl)diazen-1-ium-1,2-diolate] and V-PROLI/NO (O2-vinyl-[2-(carboxylato)pyrrolidin-1-yl]diazen-1-ium-1,2-diolate), two structurally similar diazeniumdiolate derivatives, were designed as liver-selective prodrugs that are metabolized by cytochrome P450 isoenzymes, with subsequent release of nitric oxide (NO). Yet, their efficacy in the treatment of nonalcoholic fatty liver disease (NAFLD) and their comparative pharmacokinetic and metabolic profiles have not been characterized. The aim of the present work was to compare the effects of V-PYRRO/NO and V-PROLI/NO on liver steatosis, glucose tolerance, and liver fatty acid composition in C57BL/6J mice fed a high-fat diet, as well as to comprehensively characterize the ADME (absorption, distribution, metabolism and excretion) profiles of both NO donors. Despite their similar structure, V-PYRRO/NO and V-PROLI/NO showed differences in pharmacological efficacy in the murine model of NAFLD. V-PYRRO/NO, but not V-PROLI/NO, attenuated liver steatosis, improved glucose tolerance, and favorably modified fatty acid composition in the liver. Both compounds were characterized by rapid absorption following i.p. administration, rapid elimination from the body, and incomplete bioavailability. However, V-PYRRO/NO was eliminated mainly by the liver, whereas V-PROLI/NO was excreted mostly in unchanged form by the kidney. V-PYRRO/NO was metabolized by CYP2E1, CYP2C9, CYP1A2, and CYP3A4, whereas V-PROLI/NO was metabolized mainly by CYP1A2. Importantly, V-PYRRO/NO was a better NO releaser in vivo and in the isolated, perfused liver than V-PROLI/NO, an effect compatible with the superior antisteatotic activity of V-PYRRO/NO. In conclusion, V-PYRRO/NO displayed a pronounced antisteatotic effect associated with liver-targeted NO release, whereas V-PROLI/NO showed low effectiveness, was not taken up by the liver, and was eliminated mostly in unchanged form by the kidney.

Design, synthesis, and evaluation of NO-donor containing carbonic anhydrase inhibitors to lower intraocular pressure.

The antiglaucoma drugs dorzolamide (1) and brinzolamide (2) lower intraocular pressure (IOP) by inhibiting the carbonic anhydrase (CA) enzyme to reduce aqueous humor production. The introduction of a nitric oxide (NO) donor into the alkyl side chain of dorzolamide (1) and brinzolamide (2) has led to the discovery of NO-dorzolamide 3a and NO-brinzolamide 4a, which could lower IOP through two mechanisms: CA inhibition to decrease aqueous humor secretion (reduce inflow) and NO release to increase aqueous humor drainage (increase outflow). Compounds 3a and 4a have shown improved efficacy of lowering IOP in both rabbits and monkeys compared to brinzolamide (2).

Proteomic analysis of human glioblastoma cell lines differently resistant to a nitric oxide releasing agent.

Glioblastoma multiforme is the most aggressive astrocytoma characterized by the development of resistant cells to various cytotoxic stimuli. Nitric oxide (NO) is able to overcome tumor resistance in PTEN mutated rat C6 glioma cells due to its ability to inhibit cell growth by influencing the intracellular distribution of ceramide. The aim of this study is to monitor the effects of NO donor PAPANONOate on ceramide trafficking in human glioma cell lines, CCF-STTG1 (PTEN-mutated, p53-wt) and T98G (PTEN-harboring, p53-mutated), together with the assessment of their differential molecular signature by 2D-DIGE and MALDI mass spectrometry. In the CCF-STTG1 cell line, the results indicate that treatment with PAPANONOate decreased cell proliferation (<50%) and intracellular trafficking of ceramide, assessed by BODIPY-C5Cer, while these events were not observed in the T98G cell line. Proteomic results suggest that CCF-STTG1 cells are characterized by an increased expression of proteins involved in NO-associated ER stress (i.e. protein disulfide-isomerase A3, calreticulin, 78 kDa glucose-regulated protein), which could compromise ceramide delivery from ER to Golgi, leading to ceramide accumulation in ER and partial growth arrest. Conversely, T98G cell lines, resistant to NO exposure, are characterized by increased levels of cytosolic antioxidant proteins (i.e. glutathione-S-transferase P, peroxiredoxin 1), which might buffer intracellular NO. By providing differential ceramide distribution after NO exposure and differential protein expression of two high grade glioma cell lines, this study highlights specific proteins as possible markers for tumor aggressiveness. This study demonstrates that, in two different high grade glioma cell lines, NO exposure results in a different ceramide distribution and protein expression. Furthermore, this study highlights specific proteins as possible markers for tumor aggressiveness.

Characterization of the anti-inflammatory properties of NCX 429, a dual-acting compound releasing nitric oxide and naproxen.

AIMS: Cyclooxygenase (COX)-inhibiting nitric oxide donors (CINODs) are a new class of drugs that structurally combine a COX inhibitor with a nitric oxide (NO) donating moiety. This combination reduces potential toxicity of the non-steroidal anti-inflammatory drugs (NSAIDs) whilst maintaining the analgesic and anti-inflammatory effects. The present study was undertaken to investigate the anti-inflammatory effects of NCX 429, a naproxen-based CINOD, and to assess the additional properties of NO donation beyond those related to naproxen. MAIN METHODS: We evaluated the in vitro effects of NCX 429 on oxy-radical production, phagocytosis, cytokine release, MMP-9, PPARγ expression and NF-κB activation in human monocytes/MDM and compared to naproxen. Moreover, we compared the in vivo efficacy of NCX 429 and naproxen in a murine model of peritonitis. KEY FINDINGS: In all the experiments performed in vitro, NCX 429 reduced the inflammatory responses with equal or higher efficacy compared to naproxen. Moreover, in in vivo experiments, NCX 429, at the lowest dose tested, was able to significantly inhibit cell influx in response to IL-1ß administration although naproxen was found to be more potent than NCX 429 at reducing PGE2 in inflammatory exudates. SIGNIFICANCE: These results demonstrate that both in vitro and in vivo--in a murine model of peritonitis--NCX 429 elicits significant anti-inflammatory activity, beyond the simple COX inhibition or pure NO release. Therefore, NO donation along with COX inhibition may represent a strategy for investigating inflammatory diseases in which pain and function are not fully resolved by analgesics/anti-inflammatory drugs.

Effect of a Pluronic(®) P123 formulation on the nitric oxide-generating drug JS-K.

PURPOSE: O(2)-(2,4-dinitrophenyl)1-[(4-ethoxycarbonyl)piperazin-1-yl]diazen-1-ium-1,2-diolate] or JS-K is a nitric oxide-producing prodrug of the arylated diazeniumdiolate class with promising anti-tumor activity. JS-K has challenging solubility and stability properties. We aimed to characterize and compare Pluronic(®) P123-formulated JS-K (P123/JS-K) with free JS-K. METHODS: We determined micelle size, shape, and critical micelle concentration of Pluronic(®) P123. Efficacy was evaluated in vitro using HL-60 and U937 cells and in vivo in a xenograft in NOD/SCID IL2Rγ (null) mice using HL-60 cells. We compared JS-K and P123/JS-K stability in different media. We also compared plasma protein binding of JS-K and P123/JS-K. We determined the binding and Stern Volmer constants, and thermodynamic parameters. RESULTS: Spherical P123/JS-K micelles were smaller than blank P123. P123/JS-K formulation was more stable in buffered saline, whole blood, plasma and RPMI media as compared to free JS-K. P123 affected the protein binding properties of JS-K. In vitro it was as efficacious as JS-K alone when tested in HL-60 and U937 cells and in vivo greater tumor regression was observed for P123/JS-K treated NOD/SCID IL2Rγ (null) mice when compared to free JS-K-treated NOD/SCID IL2Rγ (null) mice. CONCLUSIONS: Pluronic(®) P123 solubilizes, stabilizes and affects the protein binding characteristics of JS-K. P123/JS-K showed more in vivo anti-tumor activity than free JS-K.