Zinc tetrakis(N-methyl-4'-pyridyl) porphyrinato is an effective inhibitor of stimulant-induced activation of RAW 264.7 cells

Histidine-based hydrogels via singlet-oxygen photooxidation

The formation of hydrogels by photosensitized oxidation and crosslinking of histidine-derived polymers is demonstrated for the first time. The photooxidation of pendant His mediated by singlet oxygen was used to promote covalent coupling by its dimerization. As a proof-of-concept, two systems were studied: (i) chondroitin sulfate (CS) functionalized with His, and (ii) an elastin-like peptide (ELP) containing His produced by recombinant techniques. Both materials were crosslinked by irradiation at 425 nm in the presence of Zn-porphyrin derivatives yielding His-based hydrogels. The molecular structure and physicochemical properties of ELP-His and other 5 ELPs with photooxidizable amino acids were studied in silica by computer simulation. A correlation between the protein conformation and its elastic properties is discussed. CS-His hydrogels demonstrate larger storage moduli than ELPs with other amino acids. The obtained results show the potential use of photooxidation to create a new type of His-based hydrogels.

Unconventional neuroprotection against Ca2+ -dependent insults by metalloporphyrin catalytic antioxidants

We evaluated whether both inert and catalytically active metalloporphyrin antioxidants, meso-substituted with either phenyl-based or N-alkylpyridinium-based groups, suppress Ca(2+)-dependent neurotoxicity in cell culture models of relevance to cerebral ischemia. Representatives from both metalloporphyrin classes, regardless of antioxidant strength, protected cultured cortical neurons or PC-12 cultures against the Ca(2+) ionophores ionomycin or A23187, by suppressing neurotoxic Ca(2+) influx. Some metalloporphyrins suppressed excitotoxic Ca(2+) influx indirectly induced by the Ca(2+) ionophores in cortical neurons. Metalloporphyrins did not quench intracellular fluorescence, suggesting localization to the plasma membrane interface and/or interference with Ca(2+) ionophores. Metalloporphyrins suppressed ionomycin-induced Mn(2+) influx, but did not protect cortical neurons against pyrithione, a Zn(2+) ionophore. In other Ca(2+)-dependent paradigms, Ca(2+) influx via plasma membrane depolarization, but not through reversal of plasmalemmal Na(+)/Ca(2+) exchangers, was modestly suppressed by Mn(III)meso-tetrakis(4-benzoic acid)porphyrin (Mn(III)TBAP) or by an inert analog, Zn(II)TBAP. Mn(III)TBAP and Zn(II)TBAP potently protected cortical neurons against long-duration oxygen-glucose deprivation (OGD), performed in the presence of antagonists of NMDA, alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate and L-type voltage-gated Ca(2+) channels, raising the possibility of an unconventional mode of blockade of transient receptor protein melastatin 7 channels by a metalloTBAP family of metalloporphyrins. The present study extends the range of Ca(2+)-dependent insults for which metalloporphyrins demonstrate unconventional neuroprotection. MetalloTBAPs appear capable of targeting an OGD temporal continuum.

Inhibition of mitogenic stimulant-induced activation of thymocytes with zinc tetrakis-(N-methyl-4'-pyridyl) porphyrinato

Zinc porphyrins have anti-inflammatory and anti-allergic properties. The objective of the present study was to characterize the mechanism of zinc tetrakis-(N-methyl-4'-pyridyl) porphyrinato (ZnTMPyP) immune modulation by investigating its effects on the proliferative activity during thymocyte stimulation with mitogenic factors and the molecular events mediating thymocyte proliferation. The results indicate that ZnTMPyP inhibited thymocyte proliferation stimulated with various mitogenic factors, such as concanavalin A (Con A), interleukin (IL)-1beta, and lipopolysaccharide-exposed macrophage supernatant, in a concentration-dependent manner. ZnTMPyP was also effective in preventing DNA binding activity of nuclear factor kappaB (NF-kappaB) and IL-2 production by thymocytes in response to Con A or IL-1beta. Inhibition of p38 mitogen-activated protein kinase (MAPK) with SB203580 substantially inhibited Con A- or IL-1beta-induced DNA binding activity of NF-kappaB, whereas ZnTMPyP inhibited the activation of p38 MAPK. ZnTMPyP also inhibited Con A-induced chemiluminescence and tyrosine phosphorylation by thymocytes. In conclusion, our findings suggest that the antiproliferative effect of ZnTMPyP may be mediated by effective inhibition of the production of reactive oxygen species, tyrosine phosphorylation, p38 MAPK activation, NF-kappaB activation, and IL-2 production during mitogenic stimulation of thymocytes.