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Glutathione transferases are detoxification enzymes with multifaceted roles, including a role in the metabolism and scavenging of nitric oxide (NO) compounds in cells. Here, we explored the ability of Trametes versicolor glutathione transferases (GSTs) from the Omega class (TvGSTOs) to bind metal-nitrosyl compounds. TvGSTOs have been studied previously for their ligandin role and are interesting models to study protein‒ligand interactions. First, we determined the X-ray structure of the TvGSTO3S isoform bound to the dinitrosyl glutathionyl iron complex (DNGIC), a physiological compound involved in the storage of nitric oxide. Our results suggested a different binding mode compared to the one previously described in human GST Pi 1 (GSTP1). Then, we investigated the manner in which TvGSTO3S binds three nonphysiological metal-nitrosyl compounds with different metal cores (iron, ruthenium and osmium). We assayed sodium nitroprusside, a well-studied vasodilator used in cases of hypertensive crises or heart failure. Our results showed that the tested GST can bind metal-nitrosyls at two distinct binding sites. Thermal shift analysis with six isoforms of TvGSTOs identified TvGSTO6S as the best interactant. Using the Griess method, TvGSTO6S was found to improve the release of nitric oxide from sodium nitroprusside in vitro, whereas the effects of human GST alpha 1 (GSTA1) and GSTP1 were moderate. Our results open new structural perspectives for understanding the interactions of glutathione transferases with metal-nitrosyl compounds associated with the biochemical mechanisms of NO uptake/release in biological systems., Competing Interests: Declaration of competing interest The authors declare no conflict of interest., (Copyright © 2023 Elsevier Inc. All rights reserved.)

An overview on the design of nitric oxide (NO) delivering surfaces for biomedical purposes is provided, with a focus on the advances of the past 5 years. A localized supply of NO is of a particular interest due to the pleiotropic biological effects of this diatomic compound. Depending on the generated NO flux, the surface can mimic a physiological release profile to provide an activity on the vascular endothelium or an antibacterial activity. Three requirements are considered to describe the various strategies leading to a surface delivering NO. Firstly, the coating must be selected in accordance with the properties of the substrate (nature, shape, dimensions…). Secondly, the releasing and/or generating kinetics of NO should match the targeted biological application. Currently, the most promising structures are developed to provide an adaptable NO supply driven by pathophysiological needs. Finally, the biocompatibility and the stability of the surface must also be considered regarding the expected residence time of the device. A critical point of view is proposed to help readers in the design of the NO delivering surface according to its expected requirement and therapeutic purpose., (© 2022 Wiley-VCH GmbH.)

Graphical abstract Abstract S -Nitrosothiols, a class of NO donors, demonstrate potential benefits for cardiovascular diseases. Drugs for such chronic diseases require long term administration preferentially through the oral route. However, the absorption of S -nitrosothiols by the intestine, which is the first limiting barrier for their vascular bioavailability, is rarely evaluated. Using an in vitro model of intestinal barrier, based on human cells, the present work aimed at elucidating the mechanisms of intestinal transport (passive or active, paracellular or transcellular pathway) and at predicting the absorption site of three S -nitrosothiols: S -nitrosoglutathione (GSNO), S -nitroso- N -acetyl- l -cysteine (NACNO) and S -nitroso- N -acetyl- d -penicillamine (SNAP). These S -nitrosothiols include different skeletons carrying the nitroso group, which confer different physico-chemical characteristics and biological activities (antioxidant and anti-inflammatory). According to the values of apparent permeability coefficient, the three S -nitrosothiols belong to the medium class of permeability. The evaluation of the bidirectional apparent permeability demonstrated a passive diffusion of the three S -nitrosothiols. GSNO and NACNO preferentially cross the intestinal barrier though the transcellular pathway, while SNAP followed both the trans- and paracellular pathways. Finally, the permeability of NACNO was favoured at pH 6.4, which is close to the pH of the jejunal part of the intestine. Through this study, we determined the absorption mechanisms of S -nitrosothiols and postulated that they can be administrated through the oral route. [ABSTRACT FROM AUTHOR]

Purpose In a previous work, we have synthetized a new dinitrosothiol, i.e. S,S′ -dinitrosobucillamine BUC(NO) 2 combining S -nitroso -N -acetylpenicillamine (SNAP) and S -nitroso- N -acetylcysteine (NACNO) in its structure. When exposed to isolated aorta, we observed a 1.5-fold increase of • NO content and a more potent vasorelaxation (1 log higher pD 2 ) compared to NACNO and SNAP alone or combined (Dahboul et al., 2014). In the present study, we analyzed the thermodynamics and kinetics for the release of • NO through computational modeling techniques and correlated it to plasma assays. Then BUC(NO) 2 was administered in vivo to rats, assuming it will induce higher and/or longer hypotensive effects than its two constitutive S -mononitrosothiols. Methods Free energies for the release of • NO entities have been computed at the density functional theory level assuming an implicit model for the aqueous environment. Degradation products of BUC(NO) 2 were evaluated in vitro under heating and oxidizing conditions using HPLC coupled with tandem mass spectrometry (MS/MS). Plasma from rats were spiked with RSNO and kinetics of RSNO degradation was measured using the classical Griess-Saville method. Blood pressure was measured in awake male Wistar rats using telemetry (n = 5, each as its own control, 48 h wash-out periods between subcutaneous injections under transient isoflurane anesthesia, random order: 7 mL/kg vehicle, 3.5, 7, 14 μmol/kg SNAP, NACNO, BUC(NO) 2 and an equimolar mixture of SNAP + NACNO in order to mimic the number of • NO contained in BUC(NO) 2 ). Variations of mean (ΔMAP, reflecting arterial dilation) and pulse arterial pressures (ΔPAP, indirectly reflecting venodilation, used to determine effect duration) vs. baseline were recorded for 4 h. Results Computational modeling highlights the fact that the release of the first • NO radical in BUC(NO) 2 requires a free energy which is intermediate between the values obtained for SNAP and NACNO. However, the release of the second • NO radical is significantly favored by the concerted formation of an intramolecular disulfide bond. The corresponding oxidized compound was also characterized as related substance obtained under degradation conditions. The in vitro degradation rate of BUC(NO) 2 was significantly greater than for the other RSNO. For equivalent low and medium • NO-load, BUC(NO) 2 produced a hypotension identical to NACNO, SNAP and the equimolar mixture of SNAP + NACNO, but its effect was greater at higher doses (-62 ± 8 and -47 ± 14 mmHg, maximum ΔMAP for BUC(NO) 2 and SNAP + NACNO, respectively). Its duration of effect on PAP (-50%) lasted from 35 to 95 min, i.e. shorter than for the other RSNO (from 90 to 135 min for the mixture SNAP + NACNO). Conclusion A faster metabolism explains the abilities of BUC(NO) 2 to release higher amounts of • NO and to induce larger hypotension but shorter-lasting effects than those induced by the SNAP + NACNO mixture, despite an equivalent • NO-load. [ABSTRACT FROM AUTHOR]

Nitric oxide (NO) is a gaseous messenger which plays an important role in the vascular system homeostasis. Its origin includes both endogenous (catabolism of arginine catalyzed by endothelial NO synthase) and exogenous (intake of drinking water and foods) sources. The endogenous NO production decreases within ageing and cardiovascular diseases (CVDs) related to endothelial dysfunction, thus exogenous source of NO has to supply. Drugs actually used as NO donors have major drawbacks such as oxidative stress induction and tolerance phenomenon. Numerous studies highlight the potency of low molecular weight S-nitrosothiols as NO donors because they do not exhibit the previously cited side effects. However, very few reports have been focused on their bioavailability after oral administration which represents the most convenient route for the chronic treatment of CVDs. We presently study the intestine permeability of S-nitrosoglutathione (GSNO) as a NO donor by using an ex vivo model: monolayer of differentiated Caco-2 cells. NO species (nitrite, nitrate and S-nitrosothiols) apparent permeabilities were measured with the help of a fluorogenic probe (i.e. 2,3-diaminonaphthalene) and compared with reference drugs commonly used to evaluate intestine permeability. Some perspectives to improve the oral bioavailability of GSNO are indicated. [ABSTRACT FROM AUTHOR]