Iron tetrakis (N-methyl-4'-pyridyl) porphyrinato inhibits proliferative activity of thymocytes by blocking activation of p38 mitogen-activated protein kinase, nuclear factor-kappaB, and interleukin-2 secretion

Superoxide dismutase mimics: chemistry, pharmacology, and therapeutic potential

Oxidative stress has become widely viewed as an underlying condition in a number of diseases, such as ischemia-reperfusion disorders, central nervous system disorders, cardiovascular conditions, cancer, and diabetes. Thus, natural and synthetic antioxidants have been actively sought. Superoxide dismutase is a first line of defense against oxidative stress under physiological and pathological conditions. Therefore, the development of therapeutics aimed at mimicking superoxide dismutase was a natural maneuver. Metalloporphyrins, as well as Mn cyclic polyamines, Mn salen derivatives and nitroxides were all originally developed as SOD mimics. The same thermodynamic and electrostatic properties that make them potent SOD mimics may allow them to reduce other reactive species such as peroxynitrite, peroxynitrite-derived CO(3)(*-), peroxyl radical, and less efficiently H(2)O(2). By doing so SOD mimics can decrease both primary and secondary oxidative events, the latter arising from the inhibition of cellular transcriptional activity. To better judge the therapeutic potential and the advantage of one over the other type of compound, comparative studies of different classes of drugs in the same cellular and/or animal models are needed. We here provide a comprehensive overview of the chemical properties and some in vivo effects observed with various classes of compounds with a special emphasis on porphyrin-based compounds.

The acute and chronic phases of chronic relapsing experimental autoimmune encephalomyelitis (CR EAE) are ameliorated by the peroxynitrite decomposition catalyst, 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrinatoiron (III) chloride, (FeTPPS)

There is increasing evidence that the oxidative radical, peroxynitrite (ONOO(-)), is involved in the pathogenesis of inflammatory diseases including multiple sclerosis and the animal counterpart, experimental autoimmune encephalomyelitis (EAE). Compounds that impede the actions of ONOO(-) have proved useful in the control of EAE. In particular, catalytic isomerisation of ONOO(-) to inactive nitrate, through the use of metalloporphyrins, curtails the cellular response to inflammatory stimuli and halts the progression of neuroinflammation during EAE. The present study examined the pharmacological effects of the metalloporphyrin and ONOO(-) decomposition catalyst 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrinatoiron(III)chloride (FeTPPS) on the acute and relapse phases of chronic relapsing (CR) EAE. Administration of FeTPPS to CR EAE-inoculated Biozzi mice commenced either therapeutically and immediately prior to the emergence of acute or relapse symptoms, or prophylactically, from the onset of remission of acute neurological signs. Drug therapy reduced acute and relapse symptoms but, and in contrast to the former phase, was of limited benefit in preventing histological changes during the latter stage of disease. In contrast, prophylactic FeTPPS was effective in limiting CNS pathology and neurological deficits. The findings confirm the inhibitory effects of FeTPPS on acute stage EAE. Moreover, the study extends previous observations by verifying compound efficacy on relapsing disease. Use of metalloporphyrins, such as FeTPPS, again highlights the important role played by ONOO(-) in the development of inflammatory diseases such as EAE.

Neuroprotective effect of peroxynitrite decomposition catalyst and poly(adenosine diphosphate—ribose) polymerase inhibitor alone and in combination in rats with focal ischemia

Object. The authors evaluated the neuroprotective effect of 5,10,15,20-tetrakis(N-methyl-4′-pyridyl)porphyrinatoiron(III) (FeTMPyP), a peroxynitrite decomposition catalyst, and 1,5-isoquinolinediol (ISO), a poly(adenosine diphosphate [ADP]-ribose) polymerase (PARP) inhibitor, alone and in combination in rats with focal cerebral ischemia induced by middle cerebral artery occlusion (MCAO).

Methods. Male Sprague—Dawley rats were subjected to 2 hours of MCAO followed by 22 hours of reperfusion. Cerebral infarction and neurological deficits were estimated after ischemia. Intraperitoneal injections of FeTMPyP (1 and 2 mg/kg) and ISO (0.05 and 0.1 mg/kg) were administered alone or in combination in ischemic animals. The PARP activity in vehicle- and drug-treated groups was estimated using anti—poly(ADP-ribose) antibody in immunofluorescence and immunoblotting studies.

Two hours of MCAO and 22 hours of reperfusion produced significant cerebral infarction and neurological deficits. Treatment with FeTMPyP (1 and 2 mg/kg) and ISO (0.05 and 0.1 mg/kg) produced a significant reduction in cerebral infarction and neurological deficits. Combination therapy (2 mg/kg FeTMPyP and 0.1 mg/kg ISO) enhanced the inhibition of ischemic volume (77.81 ± 0.86%) compared with monotherapies (FeTMPyP 54.07 ± 5.6% and ISO 53.06 ± 3.88%). Immunoblotting and immunofluorescence studies showed PARP activation after ischemia, which was reduced by drug treatment.

Conclusions. Neuroprotection observed with FeTMPyP and ISO alone and in combination may be attributed to inhibition of the peroxynitrite—PARP cascade of cerebral ischemia/reperfusion injury.

Polysaccharide isolated from Poria cocos sclerotium induces NF-κB/Rel activation and iNOS expression through the activation of p38 kinase in murine macrophages

In our previous studies, we showed that PCSC, a polysaccharide isolated from Poria cocos, activated macrophages to induce the translocation of NF-kappaB/Rel into nucleus and DNA binding to its cognate site in the promoter of iNOS gene [Int. Immunopharmacol. 3 (2003) 1353]. In the present study, we investigated the role of p38 kinase pathway and membrane receptors (CD14, Toll-like receptor 4 (TLR4), and CR3) in mediating nitric oxide (NO) production and NF-kappaB/Rel activation induced by PCSC. Treament of RAW 264.7 cells with PCSC resulted in significant activation of p38. The specific p38 inhibitor SB203580 abrogated the PCSC-induced NF-kappaB/Rel activation and NO generation, whereas the selective mitogen-activated protein kinase/extracellular signal-regulated kinase 1 (MEK-1) inhibitor PD98059 did not affect the NF-kappaB/Rel and NO induction. Treatment of RAW 264.7 cells with anti-CD14 Ab, anti-TLR4 Ab, and anti-CR3 Absignificantly blocked PCSC-induced NO production activation. In conclusion, we demonstrate that PCSC induces NF-kappaB/Rel activation and iNOS expression through the CD14, TLR4, and CR3 membrane receptor and p38 kinase which is critically involved in the signal transduction leading to NF-kappaB/Rel activation in murine macrophages.

Neuroprotective efficacy and therapeutic time window of peroxynitrite decomposition catalysts in focal cerebral ischemia in rats

Free radicals have been implicated in cerebral ischemia reperfusion (IR) injury. Massive production of nitric oxide and superoxide results in continuous formation of peroxynitrite even several hours after IR insult. This can produce DNA strand nicks, hydroxylation and/or nitration of cytosolic components of neuron, leading to neuronal death. Peroxynitrite decomposition catalysts 5,10,15,20-tetrakis(N-methyl-4'-pyridyl)porphyrinato iron (III) (FeTMPyP) and 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrinato iron (III) (FeTPPS) have been demonstrated to protect neurons in in vitro cultures; however, their neuroprotective efficacy in cerebral IR injury has not been explored. In the present study, we investigated the efficacy and the therapeutic time window of FeTMPyP and FeTPPS in focal cerebral ischemia (FCI). FCI was induced according to the middle cerebral artery occlusion (MCAO) method. After 2 h of MCAO and 70 h of reperfusion, the extent of neurological deficits, infarct and edema volume were measured in Sprague-Dawley rats. FeTMPyP and FeTPPS were administered at different time points 2, 6, 9 and 12 h post MCAO. FeTMPyP and FeTPPS (3 mg kg(-1), i.v.) treatment at 2 and 6 h post MCAO produced significant reduction in infarct volume, edema volume and neurological deficits. However, treatment at latter time points did not produce significant neuroprotection. Significant reduction of peroxynitrite in blood and nitrotyrosine in brain sections was observed on FeTMPyP and FeTPPS treatment. As delayed treatment of FeTMPyP and FeTPPS produced neuroprotection, we tested whether treatment had any influence over the apoptotic neuronal death. DNA fragmentation and in situ nick end-labeling assays showed that FeTMPyP and FeTPPS treatment reduced IR injury-induced DNA fragmentation. In conclusion, peroxynitrite decomposition catalysts (FeTMPyP and FeTPPS) produced prominent neuroprotection even if administered 6 h post MCAO and the neuroprotective effect is at least in part due to the reduction of peroxynitrite and apoptosis.