Nitric oxide release and distribution following oral and intraperitoneal administration of nitroaspirin (NCX 4016) in the rat

Abstract

The metabolic fate of nitric oxide (NO) released from nitroaspirin, benzoic acid, 2-(acetyloxy)-3-[(nitrooxy)methyl]phenyl ester (NCX 4016), the lead compound of a new class of NO-releasing non steroidal anti-inflammatory drugs (NO-NSAIDs), has been studied in the rat following p.o. and i.p. administration of 100 mg/kg, by monitoring in plasma the bioactive storage forms of NO (S-nitrosothiols, RS-NO) and its oxidation products (nitrites/nitrates, NOx) by a chemiluminescent assay. In parallel, plasma was analyzed for unchanged drug and metabolites by reverse-phase HPLC. In orally treated rats, no unchanged drug is observed in the 0 -24 h interval post-dosing, but only salicylic acid (SA), NOx and RS-NO. The time-course of SA formation parallels that of plasma NOx (plateau after 6 h). Nitrosothiols in plasma are detectable at 1 h, peak at 4 h postadministration, and decline thereafter. The results relative to i.p. administration show a more pronounced and rapid NO delivery (peak of both NOx and RS-NO at 1 h and plateau between 1 and 2 h), still coincident with the peak of SA, and the presence in plasma of NCX 4015 (a metabolite of NCX 4016 which still bears the nitrate function). In myocardial tissue from p.o. treated rats, no drug or metabolites were ever detected, and the NOx levels were always in the range of the controls. Conversely, following i.p. treatment, we observed a rapid compartmentalization within the heart of the unchanged drug, which rapidly disappears in favour of its breakdown products NCX 4015 and SA, with a concomitant rise in myocardial NOx levels up to 2 h. To check the stability of NCX 4016 in the acidic gastric milieu and to explain the different distribution of the drug following p.o. or i.p. administration, the gastric content of the orally-treated animals at different post-dosing times was analysed by HPLC. The unchanged drug was detected up to 8 h post-dosing (levels slowly decreased with time), and the only metabolite to be detected was the O-deacetylated derivative (NCX 4023), which was present in low concentrations up to 4 h post-dosing. This indicates that NCX 4016 does not undergo biotransformation in the upper part of gastrointestinal tract (no direct release of NO in this district) and that the stomach acts as a reservoir for the drug.

NO-donating NSAIDs and cancer: An overview with a note on whether NO is required for their action

“…As mentioned earlier, NO-ASA traverses the stomach intact [17,18], thus ruling out such a mechanism. Therefore, the only remaining possibility, that could link gastric cytoprotection to the NO that is released from NO-NSAIDs, is that NO reaches the mucosa via the circulation.…”

“…First, NO levels (measured as NOx) are increased in the circulation following NO-NSAID administration [17,42]. Second, no intact NO-NSAID has been identified in the circulation or target tissues [17,18] and our own unpublished data], suggesting that the breakdown of the NO-NSAID molecule occurs either prior to or rapidly after it reaches the circulation. Third, S-nitrosylation, an unambiguous marker of NO action, following exposure to NO-NSAIDs has been repeatedly identified [43].…”

“…The strongest evidence against this mechanism comes form the pharmacokinetic studies of NO-aspirin (NO-ASA). Carini et al have shown that NO-ASA traverses the stomach intact, thus ruling out this mechanism, at least in the case of NO-ASA [17,18]. The alternative explanation that NO, released beyond the upper GI tract, can reach the gastric mucosa via the circulation remains unproven; elevated NO levels in the circulation following the administration of NO-NSAIDs have been repeatedly demonstrated (e.g., [18]).…”

In vitro immuno-modulatory ability of tryptic caseinate hydrolysate affected by prior caseinate glycation using the Maillard reaction or transglutaminase

“…However, chemical modifications of proteins can lead to both structure and property innate and adaptive immunity and their roles in phagocytosis (Kim et al, 2013). Macrophages can stimulate lymphocytes and other immune cells (Luft, 2008), and defend against pathogen invasion by producing these pro-inflammatory cytokines such as tumor necrosis factor-α (TNF-α) and IL-1 (Balkwill, 1992), or by releasing those cytotoxic and inflammatory molecules such as nitric oxide (NO) and reactive oxygen species (ROS) (Carini et al, 2004;Goossens, Grooten, De Vos, & Fiers, 1995). In addition, NK cells play a particularly important role in the suppression of tumor growth and metastasis (Lee, Lee, & Lim, 2014;Vivier, Tomasello, Baratin, Walzer, & Ugolini, 2008).…”

Immunostimulating Activity by Polysaccharides Isolated from Fruiting Body of Inonotus obliquus

“…When the body is stimulated by pathologic stimuli or injury, phagocytosis is the first step in the macrophage response to pathogens. In addition, macrophages can defend against pathogen invasion by secreting pro-inflammatory cytokines [e.g., tumor necrosis factor (TNF)-α and IL-1] (Balkwill, 2009) and releasing cytotoxic and inflammatory molecules [e.g., nitric oxide (NO) and reactive oxygen species (ROS)] (Carini et al, 2004;Goossens et al, 1995).…”