Targeting Nitric Oxide (NO) Deliveryin Vivo. Design of a Liver-Selective NO Donor Prodrug That Blocks Tumor Necrosis Factor-α-Induced Apoptosis and Toxicity in the Liver

Abstract

We have designed a drug that protects the liver from apoptotic cell death by organ-selective pharmacological generation of the bioregulatory agent, nitric oxide (NO). The discovery strategy involved three steps: identifying a diazeniumdiolate ion (R2N[N(O)NO]-, where R2N = pyrrolidinyl) that spontaneously decomposes to NO with a very short half-life (3 s) at physiological pH; converting this ion to a series of potential prodrug derivatives by covalent attachment of protecting groups that we postulated might be rapidly removed by enzymes prevalent in the liver; and screening the prodrug candidates in vitro and in vivo to select a lead and to confirm the desired activity. Of five cell types examined, only cultured hepatocytes metabolized O2-vinyl 1-(pyrrolidin-1-yl)diazen-1-ium-1,2-diolate (V-PYRRO/NO) to NO, triggering cyclic guanosine 3',5'-monophosphate (cGMP) synthesis and protecting the hepatocytes from apoptotic cell death induced by treatment with tumor necrosis factor-alpha (TNF alpha) plus actinomycin D. In vivo, V-PYRRO/NO increased liver cGMP levels while minimally affecting systemic hemodynamics, protecting rats dosed with TNF alpha plus galactosamine from apoptosis and hepatotoxicity. The results illustrate the potential utility of diazeniumdiolates for targeting NO delivery in vivo and suggest a possible therapeutic strategy for hepatic disorders such as fulminant liver failure.

Inflammatory Modulation of Hepatocyte Apoptosis by Nitric Oxide: In Vivo, In Vitro, and In Silico Studies

“…Expression of iNOS has also been shown to contribute to toxicity in models of alcohol-induced cirrhosis [23] and hepatitis induced by concanavalin A or acetaminophen. [22,29,30] These observations stand in contrast to studies in animal models of endotoxemia, [31,32] lipopolysaccharide/D-galactosamine (LPS/D-gal) administration, [33] hepatic regeneration [21] and cold ischemia/reperfusion following transplantation. [34] In each of these settings, either the absence or the inhibition of iNOS resulted in enhanced hepatocyte apoptosis.…”

“…Using a liver selective NO• donor, it was demonstrated that NO• almost completely inhibited the widespread cell death seen in this model. [33] Although the anti-apoptotic actions are profound, other iNOS-mediated protective effects include the inhibition of PMN influx [35] and improved liver perfusion. [36] The…”

Dexamethasone protects primary cultured hepatocytes from death receptor-mediated apoptosis by upregulation of cFLIP

“…We and others have showed that administration with the agonistic anti-Fas antibody Jo2 and TNF-a þ GalN trigger fulminant hepatic failure by inducing in vivo caspase-dependent apoptosis. 22,23 We determined whether DEX prevents the apoptotic signaling pathway and liver injury in animal models. Intraperitoneal injection with DEX significantly increased cFLIP L -p43 expression in liver tissues compared with controls ( Figure 8a).…”

Synthesis, nitric oxide release, and anti-leukemic activity of glutathione-activated nitric oxide prodrugs: Structural analogues of PABA/NO, an anti-cancer lead compound

“…PABA/NO and several ester derivatives (9)(10)(11)(12)(13)(14) differing in the substitution pattern in the aroate ester functionality were synthesized in moderate to good yields from 7 or 8 (Table 1).…”