Search results for "Nitrous Acid"
showing 10 items of 42 documents
The effects of nitric oxide on striatal serotoninergic transmission involve multiple targets: an in vivo microdialysis study in the awake rat
2004
Abstract The role of endogenous nitric oxide (NO) in N -methyl- d -aspartate (NMDA)-induced modulation of serotonin (5-HT) release in the striatum of freely moving rats has been studied using microdialysis technique. NMDA-induced increase in 5-HT release was significantly inhibited by selective nitric oxide synthase (nNOS) inhibitor S -methylthiocitrulline (S-Me-TC), ONOO − scavenger l -cysteine ( l -cys), and guanylate cyclase (GC) inhibitor 1 H [1,2,4]oxadiazolo[4,3- a ]quinoxalin-1-one (ODQ). These data suggest that modulation of 5-HT levels is linked to the formation of NO produced by NMDA receptor activation and that endogenously produced NO increases 5-HT concentrations both by stimul…
HONO Emissions from Soil Bacteria as a Major Source of Atmospheric Reactive Nitrogen
2013
From Soil to Sky Trace gases emitted either through the activity of microbial communities or from abiotic reactions in the soil influence atmospheric chemistry. In laboratory column experiments using several soil types, Oswald et al. (p. 1233 ) showed that soils from arid regions and farmlands can produce substantial quantities of nitric oxide (NO) and nitrous acid (HONO). Ammonia-oxidizing bacteria are the primary source of HONO at comparable levels to NO, thus serving as an important source of reactive nitrogen to the atmosphere.
ChemInform Abstract: Synthesis and Antineoplastic Activity of New 4-Diazopyrazole Derivatives.
2010
Several new 4-diazopyrazole derivatives were synthesized by reaction of 1-(R-substituted)phenyl-3-methyl-5-benzamidopyrazoles with a sevenfold excess of nitrous acid in acetic media. The compounds were tested at 20 microM concentration for their antineoplastic activity in vitro against Raji (human Burkitt lymphoma), K562 (human chronic myelogenous leukemia) and U937 (human histiocytic lymphoma) cell lines. They showed a percent of growth inhibition in the range 23.4-100%.
Drugs modulating the biological effects of peroxynitrite and related nitrogen species.
2007
The term “reactive nitrogen species” includes nitrogen monoxide, commonly called nitric oxide, and some other remarkable chemical entities (peroxynitrite, nitrosoperoxycarbonate, etc.) formed mostly from nitrogen monoxide itself in biological environments. Regardless of the specific mechanisms implicated in their effects, however, it is clear that an integrated pharmacological approach to peroxynitrite and related species is only just beginning to take shape. The array of affected chemical and pathological processes is extremely broad. One of the most conspicuous mechanisms observed thus far has been the scavenging of the peroxynitrite anion by molecules endowed with antioxidant activity. T…
Increased Circulating Levels of 3-Nitrotyrosine Autoantibodies
2012
3-nitrotyrosine formation is an oxidative protein modification that was first discovered in vivo in the early 1990s by Beckman and colleagues.1,2 The biological relevance of this process was extensively investigated in the subsequent years and further facilitated by the development of 3-nitrotyrosine–specific antibodies.3 Protein tyrosine nitration is mainly mediated by 3 biochemical processes (Figure): (1) by peroxynitrite (ONOO−) formation,4–6 the reaction product of nitric oxide (•NO) and superoxide (•O2−); (2) by a (myelo)peroxidase-catalyzed nitrogen dioxide radical (•NO2) formation from hydrogen peroxide and nitrite;7,8 and (3) by a nonspecific formation of the nitrogen dioxide radica…
Conversion of biliverdin to bilirubin by biliverdin reductase contributes to endothelial cell protection by heme oxygenase-1—evidence for direct and …
2009
Heme oxygenase-1 (HO-1) is highly protective in various pathophysiological states such as cardiovascular and neurodegenerative diseases. HO-1-derived bilirubin is an efficient scavenger of reactive oxygen and nitrogen species (RONS). It remains to determine whether conversion of biliverdin to bilirubin is an essential step for HO-1-conferred protection of endothelial cells. RONS scavenging activities of biliverdin versus bilirubin were assessed by different RONS generating systems and detection techniques. We also silenced the biliverdin reductase (BVR) or HO-1 gene in cultured primary human endothelial cells (HUVECs) and measured the effect on RONS formation upon stimulation with lipopolys…
Endogenous peroxynitrite modulates PGHS-1–dependent thromboxane A2 formation and aggregation in human platelets
2008
Aggregation of activated platelets is considerably mediated by the autocrine action of thromboxane A2 (TxA2) which is formed in a prostaglandin endoperoxide H2 synthase-1 (PGHS-1 or COX-1)-dependent manner. The activity of PGHS-1 can be stimulated by peroxides, an effect termed "peroxide tone", that renders PGHS-1 the key regulatory enzyme in the formation of TxA2. Activated platelets release nitric oxide (*NO) and superoxide (O*2) but their interactions with the prostanoid pathway have been controversially discussed in platelet physiology and pathophysiology. The current study demonstrates that endogenously formed peroxynitrite at nanomolar concentrations, originating from the interaction …
Metal ions modify DNA-protecting and mutagen-scavenging capacities of the AV-153 1,4-dihydropyridine.
2019
Abstract 1,4-Dihydropyridines (1,4-DHP) possess important biochemical and pharmacological properties, including antioxidant and antimutagenic activities. AV-153-Na, an antimutagenic and DNA-repair enhancing compound was shown to interact with DNA by intercalation. Here we studied DNA binding of several AV-153 salts to evaluate the impact of AV-153 modifications on its DNA binding capacity, the ability to scavenge the peroxynitrite, to protect HeLa and B-cells cells against DNA damage. Affinity of the AV-153 salts to DNA measured by a fluorescence assay was dependent on the metal ion forming a salt in position 4 of the 1,4-DHP, and it decreased as follows: Mg > Na > Ca > Li > Rb > K. AV-153-…
ChemInform Abstract: Antimicrobial and Antineoplastic Activities of New 4-Diazopyrazole Derivatives.
2010
Abstract Several new 4-diazopyrazole derivatives were prepared by the reaction of 3-methyl-5(substituted-benzamido)pyrazoles with an excess of nitrous acid in acetic acid solution. The compounds were tested for antiretroviral activity in HIV-1 infected MT-4 cells and antiproliferative effects against a panel of human leukemia, lymphoma and solid tumor cell lines. They were also tested for activity against representative gram-negative ( Shigella, Salmonella ) and gram-positive ( S. aureus, D group Streptococcus ) bacteria as well as fungi ( C. albicans, C. paratropicalis, C. neoformans and A. fumigatus ). Compounds were devoid of anti HIV-1 and antimicotic activities, whereas they were activ…
New 1,4-Dihydropyridines Down-regulate Nitric Oxide in Animals with Streptozotocin-induced Diabetes Mellitus and Protect Deoxyribonucleic Acid agains…
2015
Diabetes mellitus (DM) and its complications cause numerous health and social problems throughout the world. Pathogenic actions of nitric oxide (NO) are responsible to a large extent for development of complications of DM. Search for compounds regulating NO production in patients with DM is thus important for the development of pharmacological drugs. Dihydropyridines (1,4-DHPs) are prospective compounds from this point of view. The goals of this study were to study the in vivo effects of new DHPs on NO and reactive nitrogen and oxygen species production in a streptozotocin (STZ)-induced model of DM in rats and to study their ability to protect DNA against nocive action of peroxynitrite. STZ…