Sutherlandia (Sutherlandia frutescens) and elderberry
(Sambucus spp.) are used to promote health and for treatment of a
number of ailments. Although studies with cultured cells have demonstrated ...antioxidative
and anti-inflammatory properties of these botanicals, little is known about their ability
to mitigate brain injury. In this study, C57BL/6 J male mice were fed AIN93G diets without
or with Sutherlandia or American elderberry for 2 months prior to a 30-min global cerebral
ischemia induced by occlusion of the bilateral common carotid arteries (BCCAs), followed
by reperfusion for 3 days. Accelerating rotarod assessment at 24 h after BCCA occlusion
showed amelioration of sensorimotor impairment in the mice fed the supplemented diets as
compared with the ischemic mice fed the control diet. Quantitative digital pathology
assessment of brain slides stained with cresyl violet at 3 days after ischemia/reperfusion
(I/R) revealed significant reduction in neuronal cell death in both dietary groups.
Immunohistochemical staining for ionized calcium-binding adapter molecule-1 demonstrated
pronounced activation of microglia in the hippocampus and striatum in the ischemic brains
3 days after I/R, and microglial activation was significantly reduced in animals fed
supplemented diets. Mitigation of microglial activation by the supplements was further
supported by the decrease in expression of p47phox, a cytosolic subunit of NADPH oxidase,
and phospho-ERK1/2, a mitogen-activated protein kinase known to mediate a number of
cytoplasmic processes including oxidative stress and neuroinflammatory responses. These
results demonstrate neuroprotective effect of Sutherlandia and American elderberry
botanicals against oxidative and inflammatory responses to cerebral I/R.
Under ambient air conditions, NO inhibits NMDAR activity by reacting with the NR2A subunit C399 along with two additional cysteine pairs if their disulfide bonds are reduced to free thiol groups ...NR1(C744,C798); NR2(C87,C320). Here we demonstrate that relative hypoxia enhances S-nitrosylation of NMDARs by a unique mechanism involving an “NO-reactive oxygen sensor motif” whose determinants include C744 and C798 of the NR1 subunit. Redox reactions involving these two thiol groups sensitize other NMDAR sites to S-nitrosylation and consequent receptor inhibition, while their own nitrosylation has little effect on NMDAR activity. The crystal structure of the ligand-binding domain of NR1 reveals a flexible disulfide bond (C744-C798), which may account for its susceptibility to reduction and subsequent reaction with NO that is observed with biochemical techniques. These thiols may be nitrosylated preferentially during increasing hypoxia or stroke conditions, thus preventing excessive activity associated with cytotoxicity while avoiding blockade of physiologically active NMDARs.
SB-3CT is a potent and selective inhibitor of matrix metalloproteinase (MMP)-2 and -9, which has shown efficacy in an animal model of severe traumatic brain injury (TBI). However, SB-3CT is poorly ...water-soluble and is metabolized primarily to p-hydroxy SB-3CT (2), a more potent inhibitor than SB-3CT. We synthesized the O-phosphate prodrug (3) of compound 2 to enhance its water solubility by more than 2000-fold. The prodrug 3 was a poor MMP inhibitor, but readily hydrolyzed to the active 2 in human blood. Pharmacokinetics and brain distribution studies in mice showed that 2 crossed the blood-brain barrier (BBB) and achieved therapeutic concentrations in the brain. The prodrug 3/compound 2 was evaluated in a mouse model of severe TBI and found to significantly decrease the brain lesion volume and improve neurological outcomes. MMP-9 inhibition by a water-soluble thiirane inhibitor is a promising therapy for treatment of TBI.
A large group of flavonoids found in fruits and vegetables have been suggested to elicit health benefits due mainly to their anti-oxidative and anti-inflammatory properties. Recent studies with ...immune cells have demonstrated inhibition of these inflammatory responses through down-regulation of the pro-inflammatory pathway involving NF-KB and up-regulation of the anti-oxidative pathway involving Nrf2. In the present study, the murine BV-2 microglial cells were used to compare anti-inflammatory activity of quercetin and cyanidin, two flavonoids differing by their alpha, beta keto carbonyl group. Quercetin was 10 folds more potent than cyanidin in inhibition of lipopolysaccharide (LPS)-induced NO production as well as stimulation of Nrf2-induced heme-oxygenase-1 (HO-1) protein expression. In addition, quercetin demonstrated enhanced ability to stimulate HO-1 protein expression when cells were treated with LPS. In an attempt to unveil mechanism(s) for quercetin to enhance Nrf2/HO-1 activity under endotoxic stress, results pointed to an increase in phospho-p38MAPK expression upon addition of quercetin to LPS. In addition, pharmacological inhibitors for phospho-p38MAPK and MEK1/2 for ERK1/2 further showed that these MAPKs target different sites of the Nrf2 pathway that regulates HO-1 expression. However, inhibition of LPS-induced NO by quercetin was not fully reversed by TinPPIX, a specific inhibitor for HO-1 activity. Taken together, results suggest an important role of quercetin to regulate inflammatory responses in microglial cells and its ability to upregulate HO-1 against endotoxic stress through involvement of MAPKs.
Under ambient air conditions, NO inhibits NMDA-sensitive glutamate receptor responses by reacting with C399 of the NR2A subunit as well as possibly with two pairs of cysteine residues if their ...disulfide bonds are reduced to free thiol (C744, C798 in NR1 and C87, C320 in NR2). Here we demonstrate that relative hypoxia enhances S-nitrosylation of NMDA receptors by a unique mechanism involving NR1(C744,C798), which constitutes a novel ‘NO-reactive oxygen sensor motif.’ These two critical thiol groups sensitize other sites on the NMDA receptor to S-nitrosylation and consequent inhibition of receptor activity, while manifesting little if any effect on NMDA receptor activity by their own nitrosylation. The crystal structure of NR1 reveals a uniquely flexible (C744-C798) disulfide bond, which may account for the susceptibility of these two cysteines to reduction and subsequent facile oxidation by NO, as observed with biochemical techniques. Our findings have important implications for the treatment of hypoxia/stroke because these thiol groups can be nitrosylated preferentially during relative hypoxia, thus abrogating excessive activity associated with cytotoxicity while avoiding side effects caused by blockade of normal NMDA receptors.
PDF
